* [RFC PATCH v6 01/12] livepatch: Create and include UAPI headers
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-04-14 8:50 ` Petr Mladek
2022-02-16 16:39 ` [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation Joe Lawrence
` (12 subsequent siblings)
13 siblings, 1 reply; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Josh Poimboeuf <jpoimboe@redhat.com>
Define klp prefixes in include/uapi/linux/livepatch.h, and use them for
replacing hard-coded values in kernel/livepatch/core.c.
Update MAINTAINERS.
Note: Add defines to uapi as these are also to be used by a newly
introduced klp-convert script.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
MAINTAINERS | 1 +
include/linux/livepatch.h | 1 +
include/uapi/linux/livepatch.h | 15 +++++++++++++++
kernel/livepatch/core.c | 4 ++--
4 files changed, 19 insertions(+), 2 deletions(-)
create mode 100644 include/uapi/linux/livepatch.h
diff --git a/MAINTAINERS b/MAINTAINERS
index f41088418aae..3fce79715663 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11132,6 +11132,7 @@ F: arch/powerpc/include/asm/livepatch.h
F: arch/s390/include/asm/livepatch.h
F: arch/x86/include/asm/livepatch.h
F: include/linux/livepatch.h
+F: include/uapi/linux/livepatch.h
F: kernel/livepatch/
F: lib/livepatch/
F: samples/livepatch/
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 2614247a9781..0fb05aae091a 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -13,6 +13,7 @@
#include <linux/ftrace.h>
#include <linux/completion.h>
#include <linux/list.h>
+#include <uapi/linux/livepatch.h>
#if IS_ENABLED(CONFIG_LIVEPATCH)
diff --git a/include/uapi/linux/livepatch.h b/include/uapi/linux/livepatch.h
new file mode 100644
index 000000000000..e19430918a07
--- /dev/null
+++ b/include/uapi/linux/livepatch.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+
+/*
+ * livepatch.h - Kernel Live Patching Core
+ *
+ * Copyright (C) 2016 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _UAPI_LIVEPATCH_H
+#define _UAPI_LIVEPATCH_H
+
+#define KLP_RELA_PREFIX ".klp.rela."
+#define KLP_SYM_PREFIX ".klp.sym."
+
+#endif /* _UAPI_LIVEPATCH_H */
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 585494ec464f..79b380777a0b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf64_Shdr *sechdrs, const char *strtab,
/* Format: .klp.sym.sym_objname.sym_name,sympos */
cnt = sscanf(strtab + sym->st_name,
- ".klp.sym.%55[^.].%127[^,],%lu",
+ KLP_SYM_PREFIX "%55[^.].%127[^,],%lu",
sym_objname, sym_name, &sympos);
if (cnt != 3) {
pr_err("symbol %s has an incorrectly formatted name\n",
@@ -298,7 +298,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
* See comment in klp_resolve_symbols() for an explanation
* of the selected field width value.
*/
- cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]",
+ cnt = sscanf(shstrtab + sec->sh_name, KLP_RELA_PREFIX "%55[^.]",
sec_objname);
if (cnt != 1) {
pr_err("section %s has an incorrectly formatted name\n",
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 01/12] livepatch: Create and include UAPI headers
2022-02-16 16:39 ` [RFC PATCH v6 01/12] livepatch: Create and include UAPI headers Joe Lawrence
@ 2022-04-14 8:50 ` Petr Mladek
0 siblings, 0 replies; 28+ messages in thread
From: Petr Mladek @ 2022-04-14 8:50 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed 2022-02-16 11:39:29, Joe Lawrence wrote:
> From: Josh Poimboeuf <jpoimboe@redhat.com>
>
> Define klp prefixes in include/uapi/linux/livepatch.h, and use them for
> replacing hard-coded values in kernel/livepatch/core.c.
>
> Update MAINTAINERS.
>
> Note: Add defines to uapi as these are also to be used by a newly
> introduced klp-convert script.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> Signed-off-by: Joao Moreira <jmoreira@suse.de>
> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Looks straightforward:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 01/12] livepatch: Create and include UAPI headers Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-04-14 9:35 ` Petr Mladek
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
` (11 subsequent siblings)
13 siblings, 1 reply; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Joao Moreira <jmoreira@suse.de>
For automatic resolution of livepatch relocations, a file called
symbols.klp is used. This file maps symbols within every compiled kernel
object allowing the identification of symbols whose name is unique, thus
relocation can be automatically inferred, or providing information that
helps developers when code annotation is required for solving the
matter.
Add support for creating symbols.klp in the main Makefile. First, ensure
that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required
to achieve a complete symbols.klp file). Define the command to build
symbols.klp (cmd_klp_map) and hook it in the modules rule.
As it is undesirable to have symbols from livepatch objects inside
symbols.klp, make livepatches discernible by modifying
scripts/Makefile.build to create a .livepatch file for each livepatch in
$(MODVERDIR). This file then used by cmd_klp_map to identify and bypass
livepatches.
For identifying livepatches during the build process, a flag variable
LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This
way, set this flag for the livepatch sample Makefile in
samples/livepatch/Makefile.
Finally, Add a clean rule to ensure that symbols.klp is removed during
clean.
Notes:
To achieve a correct symbols.klp file, all kernel objects must be
considered, thus, its construction require these objects to be priorly
built. On the other hand, invoking scripts/Makefile.modpost without
having a complete symbols.klp in place would occasionally lead to
in-tree livepatches being post-processed incorrectly. To prevent this
from becoming a circular dependency, the construction of symbols.klp
uses non-post-processed kernel objects and such does not cause harm as
the symbols normally referenced from within livepatches are visible at
this stage. Also due to these requirements, the spot in-between modules
compilation and the invocation of scripts/Makefile.modpost was picked
for hooking cmd_klp_map.
The approach based on .livepatch files was proposed as an alternative to
using MODULE_INFO statements. This approach was originally proposed by
Miroslav Benes as a workaround for identifying livepathes without
depending on modinfo during the modpost stage. It was moved to this
patch as the approach also shown to be useful while building
symbols.klp.
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
.gitignore | 1 +
Documentation/dontdiff | 1 +
Makefile | 24 ++++++++++++++++++++++--
3 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/.gitignore b/.gitignore
index 7afd412dadd2..50638a15a527 100644
--- a/.gitignore
+++ b/.gitignore
@@ -61,6 +61,7 @@ modules.order
/vmlinux.symvers
/vmlinux-gdb.py
/vmlinuz
+/symbols.klp
/System.map
/Module.markers
/modules.builtin
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index 910b30a2a7d9..25c656fdd99f 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -76,6 +76,7 @@ Module.markers
Module.symvers
PENDING
SCCS
+symbols.klp
System.map*
TAGS
aconf
diff --git a/Makefile b/Makefile
index 0fb4f94a6885..64ec4bc8172c 100644
--- a/Makefile
+++ b/Makefile
@@ -639,8 +639,13 @@ KBUILD_MODULES :=
KBUILD_BUILTIN := 1
# If we have only "make modules", don't compile built-in objects.
+# When we're building livepatch modules, we need to consider the
+# built-in objects during the descend as well, as built-in objects may
+# hold symbols which are referenced from livepatches and are required by
+# klp-convert post-processing tool for resolving these cases.
+
ifeq ($(MAKECMDGOALS),modules)
- KBUILD_BUILTIN :=
+ KBUILD_BUILTIN := $(if $(CONFIG_LIVEPATCH),1)
endif
# If we have "make <whatever> modules", compile modules
@@ -1487,7 +1492,7 @@ MRPROPER_FILES += include/config include/generated \
arch/$(SRCARCH)/include/generated .tmp_objdiff \
debian snap tar-install \
.config .config.old .version \
- Module.symvers \
+ Module.symvers symbols.klp \
certs/signing_key.pem \
certs/x509.genkey \
vmlinux-gdb.py \
@@ -1742,7 +1747,22 @@ PHONY += modules modules_install
ifdef CONFIG_MODULES
+quiet_cmd_klp_map = KLP symbols.klp
+
+define cmd_klp_map
+ $(shell echo "klp-convert-symbol-data.0.1" > $(objtree)/symbols.klp) \
+ $(shell echo "*vmlinux" >> $(objtree)/symbols.klp) \
+ $(shell nm -f posix $(objtree)/vmlinux | cut -d\ -f1 >> $(objtree)/symbols.klp) \
+ $(foreach ko, $(sort $(shell cat modules.order)), \
+ $(eval mod = $(patsubst %.ko,%.mod,$(ko))) \
+ $(eval obj = $(patsubst %.ko,%.o,$(ko))) \
+ $(if $(shell grep -o LIVEPATCH $(mod)),, \
+ $(shell echo "*$(shell basename -s .ko $(ko))" >> $(objtree)/symbols.klp) \
+ $(shell nm -f posix $(obj) | cut -d\ -f1 >> $(objtree)/symbols.klp)))
+endef
+
modules: modules_check
+ $(if $(CONFIG_LIVEPATCH), $(call cmd,klp_map))
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
PHONY += modules_check
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation
2022-02-16 16:39 ` [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation Joe Lawrence
@ 2022-04-14 9:35 ` Petr Mladek
2022-04-14 17:59 ` Nicolas Schier
0 siblings, 1 reply; 28+ messages in thread
From: Petr Mladek @ 2022-04-14 9:35 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed 2022-02-16 11:39:30, Joe Lawrence wrote:
> From: Joao Moreira <jmoreira@suse.de>
>
> For automatic resolution of livepatch relocations, a file called
> symbols.klp is used. This file maps symbols within every compiled kernel
> object allowing the identification of symbols whose name is unique, thus
> relocation can be automatically inferred, or providing information that
> helps developers when code annotation is required for solving the
> matter.
>
> Add support for creating symbols.klp in the main Makefile. First, ensure
> that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required
> to achieve a complete symbols.klp file). Define the command to build
> symbols.klp (cmd_klp_map) and hook it in the modules rule.
>
> As it is undesirable to have symbols from livepatch objects inside
> symbols.klp, make livepatches discernible by modifying
> scripts/Makefile.build to create a .livepatch file for each livepatch in
> $(MODVERDIR). This file then used by cmd_klp_map to identify and bypass
> livepatches.
>
> For identifying livepatches during the build process, a flag variable
> LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This
> way, set this flag for the livepatch sample Makefile in
> samples/livepatch/Makefile.
I do not see the related code in scripts/Makefile.build.
> Finally, Add a clean rule to ensure that symbols.klp is removed during
> clean.
>
> Notes:
>
> To achieve a correct symbols.klp file, all kernel objects must be
> considered, thus, its construction require these objects to be priorly
> built. On the other hand, invoking scripts/Makefile.modpost without
> having a complete symbols.klp in place would occasionally lead to
> in-tree livepatches being post-processed incorrectly.
Honestly, I do not understand what it exactly means that "in-tree
livepatches would occasionally be post-processed incorrectly".
Is it the problem that modpost is not able to handle the unresolved
symbols that have to be updated by klp-convert?
> To prevent this
> from becoming a circular dependency, the construction of symbols.klp
> uses non-post-processed kernel objects and such does not cause harm as
> the symbols normally referenced from within livepatches are visible at
> this stage. Also due to these requirements, the spot in-between modules
> compilation and the invocation of scripts/Makefile.modpost was picked
> for hooking cmd_klp_map.
>
> The approach based on .livepatch files was proposed as an alternative to
> using MODULE_INFO statements. This approach was originally proposed by
> Miroslav Benes as a workaround for identifying livepathes without
> depending on modinfo during the modpost stage. It was moved to this
> patch as the approach also shown to be useful while building
> symbols.klp.
All the tricky code is removed in the 5th patch. My understanding is
that the problem causing the cyclic dependency is solved by modifying
modpost.
It looks like this patch is outdated and mostly obsoleted. On the
other hand, the commit message in 5th patch is too short.
What about merging the two patches and updating the commit message?
Best Regards,
Petr
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation
2022-04-14 9:35 ` Petr Mladek
@ 2022-04-14 17:59 ` Nicolas Schier
2022-04-18 18:12 ` Joe Lawrence
0 siblings, 1 reply; 28+ messages in thread
From: Nicolas Schier @ 2022-04-14 17:59 UTC (permalink / raw)
To: Petr Mladek; +Cc: Joe Lawrence, live-patching, linux-kernel, linux-kbuild
On Thu, Apr 14, 2022 at 11:35:42AM +0200 Petr Mladek wrote:
> On Wed 2022-02-16 11:39:30, Joe Lawrence wrote:
> > From: Joao Moreira <jmoreira@suse.de>
> >
> > For automatic resolution of livepatch relocations, a file called
> > symbols.klp is used. This file maps symbols within every compiled kernel
> > object allowing the identification of symbols whose name is unique, thus
> > relocation can be automatically inferred, or providing information that
> > helps developers when code annotation is required for solving the
> > matter.
> >
> > Add support for creating symbols.klp in the main Makefile. First, ensure
> > that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required
> > to achieve a complete symbols.klp file). Define the command to build
> > symbols.klp (cmd_klp_map) and hook it in the modules rule.
> >
> > As it is undesirable to have symbols from livepatch objects inside
> > symbols.klp, make livepatches discernible by modifying
> > scripts/Makefile.build to create a .livepatch file for each livepatch in
> > $(MODVERDIR). This file then used by cmd_klp_map to identify and bypass
> > livepatches.
> >
> > For identifying livepatches during the build process, a flag variable
> > LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This
> > way, set this flag for the livepatch sample Makefile in
> > samples/livepatch/Makefile.
>
> I do not see the related code in scripts/Makefile.build.
>
> > Finally, Add a clean rule to ensure that symbols.klp is removed during
> > clean.
> >
> > Notes:
> >
> > To achieve a correct symbols.klp file, all kernel objects must be
> > considered, thus, its construction require these objects to be priorly
> > built. On the other hand, invoking scripts/Makefile.modpost without
> > having a complete symbols.klp in place would occasionally lead to
> > in-tree livepatches being post-processed incorrectly.
>
> Honestly, I do not understand what it exactly means that "in-tree
> livepatches would occasionally be post-processed incorrectly".
>
> Is it the problem that modpost is not able to handle the unresolved
> symbols that have to be updated by klp-convert?
>
> > To prevent this
> > from becoming a circular dependency, the construction of symbols.klp
> > uses non-post-processed kernel objects and such does not cause harm as
> > the symbols normally referenced from within livepatches are visible at
> > this stage. Also due to these requirements, the spot in-between modules
> > compilation and the invocation of scripts/Makefile.modpost was picked
> > for hooking cmd_klp_map.
> >
> > The approach based on .livepatch files was proposed as an alternative to
> > using MODULE_INFO statements. This approach was originally proposed by
> > Miroslav Benes as a workaround for identifying livepathes without
> > depending on modinfo during the modpost stage. It was moved to this
> > patch as the approach also shown to be useful while building
> > symbols.klp.
>
> All the tricky code is removed in the 5th patch. My understanding is
> that the problem causing the cyclic dependency is solved by modifying
> modpost.
>
> It looks like this patch is outdated and mostly obsoleted. On the
> other hand, the commit message in 5th patch is too short.
>
> What about merging the two patches and updating the commit message?
+1
Yes, please merge those patches. These '$(shell ...)' side-effect lines in the
definition of 'cmd_klp_map' are quite confusing.
Kind regards,
Nicolas
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation
2022-04-14 17:59 ` Nicolas Schier
@ 2022-04-18 18:12 ` Joe Lawrence
0 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-04-18 18:12 UTC (permalink / raw)
To: Nicolas Schier; +Cc: Petr Mladek, live-patching, linux-kernel, linux-kbuild
On Thu, Apr 14, 2022 at 07:59:57PM +0200, Nicolas Schier wrote:
> On Thu, Apr 14, 2022 at 11:35:42AM +0200 Petr Mladek wrote:
> > On Wed 2022-02-16 11:39:30, Joe Lawrence wrote:
> > > From: Joao Moreira <jmoreira@suse.de>
> > >
> > > For automatic resolution of livepatch relocations, a file called
> > > symbols.klp is used. This file maps symbols within every compiled kernel
> > > object allowing the identification of symbols whose name is unique, thus
> > > relocation can be automatically inferred, or providing information that
> > > helps developers when code annotation is required for solving the
> > > matter.
> > >
> > > Add support for creating symbols.klp in the main Makefile. First, ensure
> > > that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required
> > > to achieve a complete symbols.klp file). Define the command to build
> > > symbols.klp (cmd_klp_map) and hook it in the modules rule.
> > >
> > > As it is undesirable to have symbols from livepatch objects inside
> > > symbols.klp, make livepatches discernible by modifying
> > > scripts/Makefile.build to create a .livepatch file for each livepatch in
> > > $(MODVERDIR). This file then used by cmd_klp_map to identify and bypass
> > > livepatches.
> > >
> > > For identifying livepatches during the build process, a flag variable
> > > LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This
> > > way, set this flag for the livepatch sample Makefile in
> > > samples/livepatch/Makefile.
> >
> > I do not see the related code in scripts/Makefile.build.
> >
> > > Finally, Add a clean rule to ensure that symbols.klp is removed during
> > > clean.
> > >
> > > Notes:
> > >
> > > To achieve a correct symbols.klp file, all kernel objects must be
> > > considered, thus, its construction require these objects to be priorly
> > > built. On the other hand, invoking scripts/Makefile.modpost without
> > > having a complete symbols.klp in place would occasionally lead to
> > > in-tree livepatches being post-processed incorrectly.
> >
> > Honestly, I do not understand what it exactly means that "in-tree
> > livepatches would occasionally be post-processed incorrectly".
> >
> > Is it the problem that modpost is not able to handle the unresolved
> > symbols that have to be updated by klp-convert?
> >
> > > To prevent this
> > > from becoming a circular dependency, the construction of symbols.klp
> > > uses non-post-processed kernel objects and such does not cause harm as
> > > the symbols normally referenced from within livepatches are visible at
> > > this stage. Also due to these requirements, the spot in-between modules
> > > compilation and the invocation of scripts/Makefile.modpost was picked
> > > for hooking cmd_klp_map.
> > >
> > > The approach based on .livepatch files was proposed as an alternative to
> > > using MODULE_INFO statements. This approach was originally proposed by
> > > Miroslav Benes as a workaround for identifying livepathes without
> > > depending on modinfo during the modpost stage. It was moved to this
> > > patch as the approach also shown to be useful while building
> > > symbols.klp.
> >
> > All the tricky code is removed in the 5th patch. My understanding is
> > that the problem causing the cyclic dependency is solved by modifying
> > modpost.
> >
> > It looks like this patch is outdated and mostly obsoleted. On the
> > other hand, the commit message in 5th patch is too short.
> >
> > What about merging the two patches and updating the commit message?
>
> +1
>
> Yes, please merge those patches. These '$(shell ...)' side-effect lines in the
> definition of 'cmd_klp_map' are quite confusing.
>
Sure. Admittedly the kbuild integration is most confusing to me, so I
leaned heavily on Joao's original notes and Masahiro's gracious tips and
refactored code. I'll try cutting to the final version in later patches
rather than providing all the (confusing) code evolution along the way.
Thanks,
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 01/12] livepatch: Create and include UAPI headers Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 02/12] kbuild: Support for symbols.klp creation Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:46 ` Joe Lawrence
` (3 more replies)
2022-02-16 16:39 ` [RFC PATCH v6 04/12] livepatch: Add klp-convert annotation helpers Joe Lawrence
` (10 subsequent siblings)
13 siblings, 4 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Josh Poimboeuf <jpoimboe@redhat.com>
Livepatches may use symbols which are not contained in its own scope,
and, because of that, may end up compiled with relocations that will
only be resolved during module load. Yet, when the referenced symbols
are not exported, solving this relocation requires information on the
object that holds the symbol (either vmlinux or modules) and its
position inside the object, as an object may contain multiple symbols
with the same name. Providing such information must be done accordingly
to what is specified in Documentation/livepatch/module-elf-format.txt.
Currently, there is no trivial way to embed the required information as
requested in the final livepatch elf object. klp-convert solves this
problem in two different forms: (i) by relying on symbols.klp, which is
built during kernel compilation, to automatically infer the relocation
targeted symbol, and, when such inference is not possible (ii) by using
annotations in the elf object to convert the relocation accordingly to
the specification, enabling it to be handled by the livepatch loader.
Given the above, create scripts/livepatch to hold tools developed for
livepatches and add source files for klp-convert there.
The core file of klp-convert is scripts/livepatch/klp-convert.c, which
implements the heuristics used to solve the relocations and the
conversion of unresolved symbols into the expected format, as defined in
[1].
klp-convert receives as arguments the symbols.klp file, an input
livepatch module to be converted and the output name for the converted
livepatch. When it starts running, klp-convert parses symbols.klp and
builds two internal lists of symbols, one containing the exported and
another containing the non-exported symbols. Then, by parsing the rela
sections in the elf object, klp-convert identifies which symbols must be
converted, which are those unresolved and that do not have a
corresponding exported symbol, and attempts to convert them accordingly
to the specification.
By using symbols.klp, klp-convert identifies which symbols have names
that only appear in a single kernel object, thus being capable of
resolving these cases without the intervention of the developer. When
various homonymous symbols exist through kernel objects, it is not
possible to infer the right one, thus klp-convert falls back into using
developer annotations. If these were not provided, then the tool will
print a list with all acceptable targets for the symbol being processed.
Annotations in the context of klp-convert are accessible as struct
klp_module_reloc entries in sections named .klp.module_relocs.<objname>.
These entries are pairs of symbol references and positions which are to
be resolved against definitions in <objname>.
Define the structure klp_module_reloc in include/linux/uapi/livepatch.h
allowing developers to annotate the livepatch source code with it.
klp-convert relies on libelf and on a list implementation. Add files
scripts/livepatch/elf.c and scripts/livepatch/elf.h, which are a libelf
interfacing layer and scripts/livepatch/list.h, which is a list
implementation.
Update Makefiles to correctly support the compilation of the new tool,
update MAINTAINERS file and add a .gitignore file.
[1] - Documentation/livepatch/module-elf-format.txt
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
MAINTAINERS | 1 +
include/uapi/linux/livepatch.h | 10 +
scripts/Makefile | 1 +
scripts/livepatch/.gitignore | 1 +
scripts/livepatch/Makefile | 5 +
scripts/livepatch/elf.c | 813 +++++++++++++++++++++++++++++
scripts/livepatch/elf.h | 74 +++
scripts/livepatch/klp-convert.c | 885 ++++++++++++++++++++++++++++++++
scripts/livepatch/klp-convert.h | 47 ++
scripts/livepatch/list.h | 391 ++++++++++++++
10 files changed, 2228 insertions(+)
create mode 100644 scripts/livepatch/.gitignore
create mode 100644 scripts/livepatch/Makefile
create mode 100644 scripts/livepatch/elf.c
create mode 100644 scripts/livepatch/elf.h
create mode 100644 scripts/livepatch/klp-convert.c
create mode 100644 scripts/livepatch/klp-convert.h
create mode 100644 scripts/livepatch/list.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 3fce79715663..a25a5dad12b6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11136,6 +11136,7 @@ F: include/uapi/linux/livepatch.h
F: kernel/livepatch/
F: lib/livepatch/
F: samples/livepatch/
+F: scripts/livepatch/
F: tools/testing/selftests/livepatch/
LLC (802.2)
diff --git a/include/uapi/linux/livepatch.h b/include/uapi/linux/livepatch.h
index e19430918a07..2ee98e985c2a 100644
--- a/include/uapi/linux/livepatch.h
+++ b/include/uapi/linux/livepatch.h
@@ -9,7 +9,17 @@
#ifndef _UAPI_LIVEPATCH_H
#define _UAPI_LIVEPATCH_H
+#include <linux/types.h>
+
#define KLP_RELA_PREFIX ".klp.rela."
#define KLP_SYM_PREFIX ".klp.sym."
+struct klp_module_reloc {
+ union {
+ void *sym;
+ __u64 sym64; /* Force 64-bit width */
+ };
+ __u32 sympos;
+} __packed;
+
#endif /* _UAPI_LIVEPATCH_H */
diff --git a/scripts/Makefile b/scripts/Makefile
index ce5aa9030b74..5e2c71b4b1e0 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -38,6 +38,7 @@ targets += module.lds
subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
subdir-$(CONFIG_MODVERSIONS) += genksyms
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
+subdir-$(CONFIG_LIVEPATCH) += livepatch
# Let clean descend into subdirs
subdir- += basic dtc gdb kconfig mod
diff --git a/scripts/livepatch/.gitignore b/scripts/livepatch/.gitignore
new file mode 100644
index 000000000000..dc22fe4b6a5b
--- /dev/null
+++ b/scripts/livepatch/.gitignore
@@ -0,0 +1 @@
+klp-convert
diff --git a/scripts/livepatch/Makefile b/scripts/livepatch/Makefile
new file mode 100644
index 000000000000..71dce0f3e893
--- /dev/null
+++ b/scripts/livepatch/Makefile
@@ -0,0 +1,5 @@
+hostprogs-always-y := klp-convert
+
+klp-convert-objs := klp-convert.o elf.o
+
+HOSTLDLIBS_klp-convert := -lelf
diff --git a/scripts/livepatch/elf.c b/scripts/livepatch/elf.c
new file mode 100644
index 000000000000..ccec857ea37e
--- /dev/null
+++ b/scripts/livepatch/elf.c
@@ -0,0 +1,813 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * elf.c - ELF access library
+ *
+ * Adapted from kpatch (https://github.com/dynup/kpatch):
+ * Copyright (C) 2013-2016 Josh Poimboeuf <jpoimboe@redhat.com>
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "elf.h"
+
+#define WARN(format, ...) \
+ fprintf(stderr, "%s: " format "\n", elf->name, ##__VA_ARGS__)
+
+/*
+ * Fallback for systems without this "read, mmaping if possible" cmd.
+ */
+#ifndef ELF_C_READ_MMAP
+#define ELF_C_READ_MMAP ELF_C_READ
+#endif
+
+bool is_rela_section(struct section *sec)
+{
+ return (sec->sh.sh_type == SHT_RELA);
+}
+
+struct section *find_section_by_name(struct elf *elf, const char *name)
+{
+ struct section *sec;
+
+ list_for_each_entry(sec, &elf->sections, list)
+ if (!strcmp(sec->name, name))
+ return sec;
+
+ return NULL;
+}
+
+static struct section *find_section_by_index(struct elf *elf,
+ unsigned int idx)
+{
+ struct section *sec;
+
+ list_for_each_entry(sec, &elf->sections, list)
+ if (sec->idx == idx)
+ return sec;
+
+ return NULL;
+}
+
+static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
+{
+ struct symbol *sym;
+
+ list_for_each_entry(sym, &elf->symbols, list)
+ if (sym->idx == idx)
+ return sym;
+
+ return NULL;
+}
+
+static int read_sections(struct elf *elf)
+{
+ Elf_Scn *s = NULL;
+ struct section *sec;
+ size_t shstrndx, sections_nr;
+ int i;
+
+ if (elf_getshdrnum(elf->elf, §ions_nr)) {
+ perror("elf_getshdrnum");
+ return -1;
+ }
+
+ if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
+ perror("elf_getshdrstrndx");
+ return -1;
+ }
+
+ for (i = 0; i < sections_nr; i++) {
+ sec = malloc(sizeof(*sec));
+ if (!sec) {
+ perror("malloc");
+ return -1;
+ }
+ memset(sec, 0, sizeof(*sec));
+
+ INIT_LIST_HEAD(&sec->relas);
+
+ list_add_tail(&sec->list, &elf->sections);
+
+ s = elf_getscn(elf->elf, i);
+ if (!s) {
+ perror("elf_getscn");
+ return -1;
+ }
+
+ sec->idx = elf_ndxscn(s);
+
+ if (!gelf_getshdr(s, &sec->sh)) {
+ perror("gelf_getshdr");
+ return -1;
+ }
+
+ sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
+ if (!sec->name) {
+ perror("elf_strptr");
+ return -1;
+ }
+
+ sec->elf_data = elf_getdata(s, NULL);
+ if (!sec->elf_data) {
+ perror("elf_getdata");
+ return -1;
+ }
+
+ if (sec->elf_data->d_off != 0 ||
+ sec->elf_data->d_size != sec->sh.sh_size) {
+ WARN("unexpected data attributes for %s", sec->name);
+ return -1;
+ }
+
+ sec->data = sec->elf_data->d_buf;
+ sec->size = sec->elf_data->d_size;
+ }
+
+ /* sanity check, one more call to elf_nextscn() should return NULL */
+ if (elf_nextscn(elf->elf, s)) {
+ WARN("section entry mismatch");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int read_symbols(struct elf *elf)
+{
+ struct section *symtab;
+ struct symbol *sym;
+ int symbols_nr, i;
+
+ symtab = find_section_by_name(elf, ".symtab");
+ if (!symtab) {
+ WARN("missing symbol table");
+ return -1;
+ }
+
+ symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
+
+ for (i = 0; i < symbols_nr; i++) {
+ sym = malloc(sizeof(*sym));
+ if (!sym) {
+ perror("malloc");
+ return -1;
+ }
+ memset(sym, 0, sizeof(*sym));
+
+ sym->idx = i;
+
+ if (!gelf_getsym(symtab->elf_data, i, &sym->sym)) {
+ perror("gelf_getsym");
+ goto err;
+ }
+
+ sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
+ sym->sym.st_name);
+ if (!sym->name) {
+ perror("elf_strptr");
+ goto err;
+ }
+
+ sym->type = GELF_ST_TYPE(sym->sym.st_info);
+ sym->bind = GELF_ST_BIND(sym->sym.st_info);
+
+ if (sym->sym.st_shndx > SHN_UNDEF &&
+ sym->sym.st_shndx < SHN_LORESERVE) {
+ sym->sec = find_section_by_index(elf,
+ sym->sym.st_shndx);
+ if (!sym->sec) {
+ WARN("couldn't find section for symbol %s",
+ sym->name);
+ goto err;
+ }
+ if (sym->type == STT_SECTION) {
+ sym->name = sym->sec->name;
+ sym->sec->sym = sym;
+ }
+ }
+
+ sym->offset = sym->sym.st_value;
+ sym->size = sym->sym.st_size;
+
+ list_add_tail(&sym->list, &elf->symbols);
+ }
+
+ return 0;
+
+err:
+ free(sym);
+ return -1;
+}
+
+static int read_relas(struct elf *elf)
+{
+ struct section *sec;
+ struct rela *rela;
+ int i;
+ unsigned int symndx;
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (sec->sh.sh_type != SHT_RELA)
+ continue;
+
+ sec->base = find_section_by_name(elf, sec->name + 5);
+ if (!sec->base) {
+ WARN("can't find base section for rela section %s",
+ sec->name);
+ return -1;
+ }
+
+ sec->base->rela = sec;
+
+ for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
+ rela = malloc(sizeof(*rela));
+ if (!rela) {
+ perror("malloc");
+ return -1;
+ }
+ memset(rela, 0, sizeof(*rela));
+
+ if (!gelf_getrela(sec->elf_data, i, &rela->rela)) {
+ perror("gelf_getrela");
+ return -1;
+ }
+
+ rela->type = GELF_R_TYPE(rela->rela.r_info);
+ rela->addend = rela->rela.r_addend;
+ rela->offset = rela->rela.r_offset;
+ symndx = GELF_R_SYM(rela->rela.r_info);
+ rela->sym = find_symbol_by_index(elf, symndx);
+ if (!rela->sym) {
+ WARN("can't find rela entry symbol %u for %s",
+ symndx, sec->name);
+ return -1;
+ }
+
+ list_add_tail(&rela->list, &sec->relas);
+ }
+ }
+
+ return 0;
+}
+
+struct section *create_rela_section(struct elf *elf, const char *name,
+ struct section *base)
+{
+ struct section *sec;
+
+ sec = malloc(sizeof(*sec));
+ if (!sec) {
+ WARN("malloc failed");
+ return NULL;
+ }
+ memset(sec, 0, sizeof(*sec));
+ INIT_LIST_HEAD(&sec->relas);
+
+ sec->base = base;
+ sec->name = strdup(name);
+ if (!sec->name) {
+ WARN("strdup failed");
+ return NULL;
+ }
+ sec->sh.sh_name = -1;
+ sec->sh.sh_type = SHT_RELA;
+
+ if (elf->elf_class == ELFCLASS32) {
+ sec->sh.sh_entsize = sizeof(Elf32_Rela);
+ sec->sh.sh_addralign = 4;
+ } else {
+ sec->sh.sh_entsize = sizeof(Elf64_Rela);
+ sec->sh.sh_addralign = 8;
+ }
+ sec->sh.sh_flags = SHF_ALLOC;
+
+ sec->elf_data = malloc(sizeof(*sec->elf_data));
+ if (!sec->elf_data) {
+ WARN("malloc failed");
+ return NULL;
+ }
+ memset(sec->elf_data, 0, sizeof(*sec->elf_data));
+ sec->elf_data->d_type = ELF_T_RELA;
+
+ list_add_tail(&sec->list, &elf->sections);
+
+ return sec;
+}
+
+static int update_shstrtab(struct elf *elf)
+{
+ struct section *shstrtab, *sec;
+ size_t orig_size, new_size = 0, offset, len;
+ char *buf;
+
+ shstrtab = find_section_by_name(elf, ".shstrtab");
+ if (!shstrtab) {
+ WARN("can't find .shstrtab");
+ return -1;
+ }
+
+ orig_size = new_size = shstrtab->size;
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (sec->sh.sh_name != -1)
+ continue;
+ new_size += strlen(sec->name) + 1;
+ }
+
+ if (new_size == orig_size)
+ return 0;
+
+ buf = malloc(new_size);
+ if (!buf) {
+ WARN("malloc failed");
+ return -1;
+ }
+ memcpy(buf, (void *)shstrtab->data, orig_size);
+
+ offset = orig_size;
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (sec->sh.sh_name != -1)
+ continue;
+ sec->sh.sh_name = offset;
+ len = strlen(sec->name) + 1;
+ memcpy(buf + offset, sec->name, len);
+ offset += len;
+ }
+
+ shstrtab->elf_data->d_buf = shstrtab->data = buf;
+ shstrtab->elf_data->d_size = shstrtab->size = new_size;
+ shstrtab->sh.sh_size = new_size;
+
+ return 1;
+}
+
+static void free_shstrtab(struct elf *elf)
+{
+ struct section *shstrtab;
+
+ shstrtab = find_section_by_name(elf, ".shstrtab");
+ if (!shstrtab)
+ return;
+
+ free(shstrtab->elf_data->d_buf);
+}
+
+static int update_strtab(struct elf *elf)
+{
+ struct section *strtab;
+ struct symbol *sym;
+ size_t orig_size, new_size = 0, offset, len;
+ char *buf;
+
+ strtab = find_section_by_name(elf, ".strtab");
+ if (!strtab) {
+ WARN("can't find .strtab");
+ return -1;
+ }
+
+ orig_size = new_size = strtab->size;
+
+ list_for_each_entry(sym, &elf->symbols, list) {
+ if (sym->sym.st_name != -1)
+ continue;
+ new_size += strlen(sym->name) + 1;
+ }
+
+ if (new_size == orig_size)
+ return 0;
+
+ buf = malloc(new_size);
+ if (!buf) {
+ WARN("malloc failed");
+ return -1;
+ }
+ memcpy(buf, (void *)strtab->data, orig_size);
+
+ offset = orig_size;
+ list_for_each_entry(sym, &elf->symbols, list) {
+ if (sym->sym.st_name != -1)
+ continue;
+ sym->sym.st_name = offset;
+ len = strlen(sym->name) + 1;
+ memcpy(buf + offset, sym->name, len);
+ offset += len;
+ }
+
+ strtab->elf_data->d_buf = strtab->data = buf;
+ strtab->elf_data->d_size = strtab->size = new_size;
+ strtab->sh.sh_size = new_size;
+
+ return 1;
+}
+
+static void free_strtab(struct elf *elf)
+{
+ struct section *strtab;
+
+ strtab = find_section_by_name(elf, ".strtab");
+ if (!strtab)
+ return;
+
+ if (strtab->elf_data)
+ free(strtab->elf_data->d_buf);
+}
+
+static int update_symtab(struct elf *elf)
+{
+ struct section *symtab, *sec;
+ struct symbol *sym;
+ char *buf;
+ size_t size;
+ int offset = 0, nr_locals = 0, idx, nr_syms;
+
+ idx = 0;
+ list_for_each_entry(sec, &elf->sections, list)
+ sec->idx = idx++;
+
+ idx = 0;
+ list_for_each_entry(sym, &elf->symbols, list) {
+ sym->idx = idx++;
+ if (sym->sec)
+ sym->sym.st_shndx = sym->sec->idx;
+ }
+ nr_syms = idx;
+
+ symtab = find_section_by_name(elf, ".symtab");
+ if (!symtab) {
+ WARN("can't find symtab");
+ return -1;
+ }
+
+ symtab->sh.sh_link = find_section_by_name(elf, ".strtab")->idx;
+
+ /* create new symtab buffer */
+ if (elf->elf_class == ELFCLASS32)
+ size = nr_syms * sizeof(Elf32_Sym);
+ else
+ size = nr_syms * sizeof(Elf64_Sym);
+ buf = malloc(size);
+ if (!buf) {
+ WARN("malloc failed");
+ return -1;
+ }
+ memset(buf, 0, size);
+
+ offset = 0;
+ list_for_each_entry(sym, &elf->symbols, list) {
+
+ if (elf->elf_class == ELFCLASS32) {
+ /* Manually convert to 32-bit Elf32_Sym */
+ Elf32_Sym sym32;
+
+ sym32.st_name = sym->sym.st_name;
+ sym32.st_info = sym->sym.st_info;
+ sym32.st_other = sym->sym.st_other;
+ sym32.st_shndx = sym->sym.st_shndx;
+ sym32.st_value = sym->sym.st_value;
+ sym32.st_size = sym->sym.st_size;
+ memcpy(buf + offset, &sym32, sizeof(Elf32_Sym));
+ } else {
+ /* Existing 64-bit GElf_Syms are fine */
+ memcpy(buf + offset, &sym->sym, sizeof(Elf64_Sym));
+ }
+
+ offset += symtab->sh.sh_entsize;
+
+ if (sym->bind == STB_LOCAL)
+ nr_locals++;
+ }
+
+ symtab->elf_data->d_buf = symtab->data = buf;
+ symtab->elf_data->d_size = symtab->size = size;
+ symtab->sh.sh_size = size;
+
+ /* update symtab section header */
+ symtab->sh.sh_info = nr_locals;
+
+ return 1;
+}
+
+static void free_symtab(struct elf *elf)
+{
+ struct section *symtab;
+
+ symtab = find_section_by_name(elf, ".symtab");
+ if (!symtab)
+ return;
+
+ free(symtab->elf_data->d_buf);
+}
+
+static int update_relas(struct elf *elf)
+{
+ struct section *sec, *symtab;
+ struct rela *rela;
+ int nr_relas, idx, size;
+ void *relas;
+
+ symtab = find_section_by_name(elf, ".symtab");
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (!is_rela_section(sec))
+ continue;
+
+ sec->sh.sh_link = symtab->idx;
+ if (sec->base)
+ sec->sh.sh_info = sec->base->idx;
+
+ nr_relas = 0;
+ list_for_each_entry(rela, &sec->relas, list)
+ nr_relas++;
+
+ if (elf->elf_class == ELFCLASS32)
+ size = nr_relas * sizeof(Elf32_Rela);
+ else
+ size = nr_relas * sizeof(Elf64_Rela);
+
+ relas = malloc(size);
+ if (!relas) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ sec->elf_data->d_buf = sec->data = relas;
+ sec->elf_data->d_size = sec->size = size;
+ sec->sh.sh_size = size;
+
+ idx = 0;
+ list_for_each_entry(rela, &sec->relas, list) {
+ if (elf->elf_class == ELFCLASS32) {
+ Elf32_Rela *relas32 = relas;
+
+ relas32[idx].r_offset = rela->offset;
+ relas32[idx].r_addend = rela->addend;
+ relas32[idx].r_info = ELF32_R_INFO(rela->sym->idx,
+ rela->type);
+ } else {
+ Elf64_Rela *relas64 = relas;
+
+ relas64[idx].r_offset = rela->offset;
+ relas64[idx].r_addend = rela->addend;
+ relas64[idx].r_info = ELF64_R_INFO(rela->sym->idx,
+ rela->type);
+ }
+ idx++;
+ }
+ }
+
+ return 1;
+}
+
+static void update_groups(struct elf *elf)
+{
+ struct section *sec, *symtab;
+
+ symtab = find_section_by_name(elf, ".symtab");
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (sec->sh.sh_type == SHT_GROUP)
+ sec->sh.sh_link = symtab->idx;
+ }
+}
+
+static void free_relas(struct elf *elf)
+{
+ struct section *sec, *symtab;
+
+ symtab = find_section_by_name(elf, ".symtab");
+ if (!symtab)
+ return;
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (!is_rela_section(sec))
+ continue;
+
+ free(sec->elf_data->d_buf);
+ }
+}
+
+static int write_file(struct elf *elf, const char *file)
+{
+ int fd;
+ Elf *e;
+ GElf_Ehdr eh, ehout;
+ Elf_Scn *scn;
+ Elf_Data *data;
+ GElf_Shdr sh;
+ struct section *sec;
+
+ fd = creat(file, 0664);
+ if (fd == -1) {
+ WARN("couldn't create %s", file);
+ return -1;
+ }
+
+ e = elf_begin(fd, ELF_C_WRITE, NULL);
+ if (!e) {
+ WARN("elf_begin failed");
+ return -1;
+ }
+
+ if (!gelf_newehdr(e, gelf_getclass(elf->elf))) {
+ WARN("gelf_newehdr failed");
+ return -1;
+ }
+
+ if (!gelf_getehdr(e, &ehout)) {
+ WARN("gelf_getehdr failed");
+ return -1;
+ }
+
+ if (!gelf_getehdr(elf->elf, &eh)) {
+ WARN("gelf_getehdr failed");
+ return -1;
+ }
+
+ memset(&ehout, 0, sizeof(ehout));
+ ehout.e_ident[EI_DATA] = eh.e_ident[EI_DATA];
+ ehout.e_machine = eh.e_machine;
+ ehout.e_type = eh.e_type;
+ ehout.e_version = EV_CURRENT;
+ ehout.e_shstrndx = find_section_by_name(elf, ".shstrtab")->idx;
+
+ list_for_each_entry(sec, &elf->sections, list) {
+ if (!sec->idx)
+ continue;
+ scn = elf_newscn(e);
+ if (!scn) {
+ WARN("elf_newscn failed");
+ return -1;
+ }
+
+ data = elf_newdata(scn);
+ if (!data) {
+ WARN("elf_newdata failed");
+ return -1;
+ }
+
+ if (!elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY)) {
+ WARN("elf_flagdata failed");
+ return -1;
+ }
+
+ data->d_type = sec->elf_data->d_type;
+ data->d_buf = sec->elf_data->d_buf;
+ data->d_size = sec->elf_data->d_size;
+
+ if (!gelf_getshdr(scn, &sh)) {
+ WARN("gelf_getshdr failed");
+ return -1;
+ }
+
+ sh = sec->sh;
+
+ if (!gelf_update_shdr(scn, &sh)) {
+ WARN("gelf_update_shdr failed");
+ return -1;
+ }
+ }
+
+ if (!gelf_update_ehdr(e, &ehout)) {
+ WARN("gelf_update_ehdr failed");
+ return -1;
+ }
+
+ if (elf_update(e, ELF_C_WRITE) < 0) {
+ fprintf(stderr, "%s\n", elf_errmsg(-1));
+ WARN("elf_update failed");
+ return -1;
+ }
+
+ elf_end(e);
+
+ return 0;
+}
+
+int elf_write_file(struct elf *elf, const char *file)
+{
+ int ret_shstrtab;
+ int ret_strtab;
+ int ret_symtab;
+ int ret_relas;
+ int ret;
+
+ ret_shstrtab = update_shstrtab(elf);
+ if (ret_shstrtab < 0)
+ return ret_shstrtab;
+
+ ret_strtab = update_strtab(elf);
+ if (ret_strtab < 0)
+ return ret_strtab;
+
+ ret_symtab = update_symtab(elf);
+ if (ret_symtab < 0)
+ return ret_symtab;
+
+ ret_relas = update_relas(elf);
+ if (ret_relas < 0)
+ return ret_relas;
+
+ update_groups(elf);
+
+ ret = write_file(elf, file);
+ if (ret)
+ return ret;
+
+ if (ret_relas > 0)
+ free_relas(elf);
+ if (ret_symtab > 0)
+ free_symtab(elf);
+ if (ret_strtab > 0)
+ free_strtab(elf);
+ if (ret_shstrtab > 0)
+ free_shstrtab(elf);
+
+ return 0;
+}
+
+struct elf *elf_open(const char *name)
+{
+ struct elf *elf;
+
+ elf_version(EV_CURRENT);
+
+ elf = malloc(sizeof(*elf));
+ if (!elf) {
+ perror("malloc");
+ return NULL;
+ }
+ memset(elf, 0, sizeof(*elf));
+
+ INIT_LIST_HEAD(&elf->sections);
+ INIT_LIST_HEAD(&elf->symbols);
+
+ elf->fd = open(name, O_RDONLY);
+ if (elf->fd == -1) {
+ perror("open");
+ goto err;
+ }
+
+ elf->elf = elf_begin(elf->fd, ELF_C_READ_MMAP, NULL);
+ if (!elf->elf) {
+ perror("elf_begin");
+ goto err;
+ }
+
+ if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
+ perror("gelf_getehdr");
+ goto err;
+ }
+
+ elf->elf_class = gelf_getclass(elf->elf);
+ if ((elf->elf_class != ELFCLASS32) && (elf->elf_class != ELFCLASS64)) {
+ WARN("invalid elf class");
+ goto err;
+ }
+
+ if (read_sections(elf))
+ goto err;
+
+ if (read_symbols(elf))
+ goto err;
+
+ if (read_relas(elf))
+ goto err;
+
+ return elf;
+
+err:
+ elf_close(elf);
+ return NULL;
+}
+
+void elf_close(struct elf *elf)
+{
+ struct section *sec, *tmpsec;
+ struct symbol *sym, *tmpsym;
+ struct rela *rela, *tmprela;
+
+ list_for_each_entry_safe(sym, tmpsym, &elf->symbols, list) {
+ list_del(&sym->list);
+ free(sym);
+ }
+ list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
+ list_for_each_entry_safe(rela, tmprela, &sec->relas, list) {
+ list_del(&rela->list);
+ free(rela);
+ }
+ list_del(&sec->list);
+ free(sec);
+ }
+ if (elf->fd > 0)
+ close(elf->fd);
+ if (elf->elf)
+ elf_end(elf->elf);
+ free(elf);
+}
diff --git a/scripts/livepatch/elf.h b/scripts/livepatch/elf.h
new file mode 100644
index 000000000000..a5969ae6a0be
--- /dev/null
+++ b/scripts/livepatch/elf.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015-2016 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _KLP_POST_ELF_H
+#define _KLP_POST_ELF_H
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <gelf.h>
+#include "list.h"
+
+#ifdef LIBELF_USE_DEPRECATED
+# define elf_getshdrnum elf_getshnum
+# define elf_getshdrstrndx elf_getshstrndx
+#endif
+
+struct section {
+ struct list_head list;
+ GElf_Shdr sh;
+ struct section *base, *rela;
+ struct list_head relas;
+ struct symbol *sym;
+ Elf_Data *elf_data;
+ char *name;
+ int idx;
+ void *data;
+ unsigned int size;
+};
+
+struct symbol {
+ struct list_head list;
+ GElf_Sym sym;
+ struct section *sec;
+ char *name;
+ unsigned int idx;
+ unsigned char bind, type;
+ unsigned long offset;
+ unsigned int size;
+};
+
+struct rela {
+ struct list_head list;
+ GElf_Rela rela;
+ struct symbol *sym;
+ struct section *klp_rela_sec;
+ unsigned int type;
+ unsigned long offset;
+ int addend;
+};
+
+struct elf {
+ Elf *elf;
+ GElf_Ehdr ehdr;
+ int fd;
+ char *name;
+ int elf_class;
+ struct list_head sections;
+ struct list_head symbols;
+};
+
+
+struct elf *elf_open(const char *name);
+bool is_rela_section(struct section *sec);
+struct section *find_section_by_name(struct elf *elf, const char *name);
+struct section *create_rela_section(struct elf *elf, const char *name,
+ struct section *base);
+
+void elf_close(struct elf *elf);
+int elf_write_file(struct elf *elf, const char *file);
+
+
+#endif /* _KLP_POST_ELF_H */
diff --git a/scripts/livepatch/klp-convert.c b/scripts/livepatch/klp-convert.c
new file mode 100644
index 000000000000..13bae5aa5208
--- /dev/null
+++ b/scripts/livepatch/klp-convert.c
@@ -0,0 +1,885 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2016 Josh Poimboeuf <jpoimboe@redhat.com>
+ * Copyright (C) 2017 Joao Moreira <jmoreira@suse.de>
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include "elf.h"
+#include "list.h"
+#include "klp-convert.h"
+
+/*
+ * Symbols parsed from symbols.klp are kept in two lists:
+ * - symbols: keeps non-exported symbols
+ * - exp_symbols: keeps exported symbols (__ksymtab_prefixed)
+ */
+static LIST_HEAD(symbols);
+static LIST_HEAD(exp_symbols);
+
+/* In-livepatch user-provided symbol positions are kept in list usr_symbols */
+static LIST_HEAD(usr_symbols);
+
+/* Converted symbols and their struct symbol -> struct sympos association */
+static LIST_HEAD(converted_symbols);
+
+struct converted_sym {
+ struct list_head list;
+ struct symbol *symbol;
+ struct sympos sympos;
+};
+
+static void free_syms_lists(void)
+{
+ struct symbol_entry *entry, *aux;
+ struct sympos *sp, *sp_aux;
+
+ list_for_each_entry_safe(entry, aux, &symbols, list) {
+ free(entry->object_name);
+ free(entry->symbol_name);
+ list_del(&entry->list);
+ free(entry);
+ }
+
+ list_for_each_entry_safe(entry, aux, &exp_symbols, list) {
+ free(entry->object_name);
+ free(entry->symbol_name);
+ list_del(&entry->list);
+ free(entry);
+ }
+
+ list_for_each_entry_safe(sp, sp_aux, &usr_symbols, list) {
+ free(sp->object_name);
+ free(sp->symbol_name);
+ list_del(&sp->list);
+ free(sp);
+ }
+}
+
+/* Parses file and fill symbols and exp_symbols list */
+static bool load_syms_lists(const char *symbols_list)
+{
+ FILE *fsyms;
+ size_t len = 0;
+ ssize_t n;
+ char *obj = NULL, *sym = NULL;
+ bool ret = false;
+
+ fsyms = fopen(symbols_list, "r");
+ if (!fsyms) {
+ WARN("Unable to open Symbol list: %s", symbols_list);
+ return false;
+ }
+
+ /* read file format version */
+ n = getline(&sym, &len, fsyms);
+ if (n <= 0) {
+ WARN("Unable to read Symbol list: %s", symbols_list);
+ goto done;
+ }
+
+ if (strncmp(sym, "klp-convert-symbol-data.0.1", 27) != 0) {
+ WARN("Symbol list is in unknown format.");
+ goto done;
+ }
+
+ len = 0;
+ free(sym);
+ sym = NULL;
+
+ /* read file */
+ n = getline(&sym, &len, fsyms);
+ while (n > 0) {
+ if (sym[n-1] == '\n')
+ sym[n-1] = '\0';
+
+ /* Objects in symbols.klp are flagged with '*' */
+ if (sym[0] == '*') {
+ free(obj);
+ obj = strdup(sym+1);
+ if (!obj) {
+ WARN("Unable to allocate object name\n");
+ goto done;
+ }
+ free(sym);
+ } else {
+ struct symbol_entry *entry;
+
+ if (!obj) {
+ WARN("File format error\n");
+ goto done;
+ }
+
+ entry = calloc(1, sizeof(struct symbol_entry));
+ if (!entry) {
+ WARN("Unable to allocate Symbol entry\n");
+ goto done;
+ }
+
+ entry->object_name = strdup(obj);
+ if (!entry->object_name) {
+ WARN("Unable to allocate entry object name\n");
+ free(entry);
+ goto done;
+ }
+
+ entry->symbol_name = sym;
+ if (strncmp(entry->symbol_name, "__ksymtab_", 10) == 0)
+ list_add(&entry->list, &exp_symbols);
+ else
+ list_add(&entry->list, &symbols);
+ }
+ len = 0;
+ sym = NULL;
+ n = getline(&sym, &len, fsyms);
+ }
+ ret = true;
+
+done:
+ free(sym);
+ free(obj);
+ fclose(fsyms);
+ return ret;
+}
+
+/* Searches for sympos of specific symbol in usr_symbols list */
+static bool get_usr_sympos(struct symbol *s, struct sympos *sp)
+{
+ struct sympos *aux;
+
+ list_for_each_entry(aux, &usr_symbols, list) {
+ if (strcmp(aux->symbol_name, s->name) == 0) {
+ sp->symbol_name = aux->symbol_name;
+ sp->object_name = aux->object_name;
+ sp->pos = aux->pos;
+ return true;
+ }
+ }
+ return false;
+}
+
+/* Removes symbols used for sympos annotation from livepatch elf object */
+static void clear_sympos_symbols(struct section *annotation_sec,
+ struct elf *klp_elf)
+{
+ struct symbol *sym, *aux;
+
+ list_for_each_entry_safe(sym, aux, &klp_elf->symbols, list) {
+ if (sym->sec == annotation_sec) {
+
+ struct section *sec;
+ struct rela *rela, *tmprela;
+
+ list_for_each_entry(sec, &klp_elf->sections, list) {
+ list_for_each_entry_safe(rela, tmprela, &sec->relas, list) {
+ if (rela->sym == sym) {
+ list_del(&rela->list);
+ free(rela);
+ }
+ }
+ }
+
+ list_del(&sym->list);
+ free(sym);
+ }
+ }
+}
+
+/* Removes annotation from livepatch elf object */
+static void clear_sympos_annontations(struct elf *klp_elf)
+{
+ struct section *sec, *aux;
+
+ list_for_each_entry_safe(sec, aux, &klp_elf->sections, list) {
+ if (strncmp(sec->name, ".klp.module_relocs.", 19) == 0) {
+ clear_sympos_symbols(sec, klp_elf);
+ list_del(&sec->list);
+ free(sec);
+ continue;
+ }
+ if (strncmp(sec->name, ".rela.klp.module_relocs.", 24) == 0) {
+
+ struct rela *rela, *tmprela;
+
+ list_for_each_entry_safe(rela, tmprela, &sec->relas, list) {
+ list_del(&rela->list);
+ free(rela);
+ }
+ list_del(&sec->list);
+ free(sec);
+ continue;
+ }
+ }
+}
+
+/*
+ * User provided sympos annotation checks:
+ * - do two or more elements in usr_symbols have the same object and
+ * name, but different symbol position
+ * - are there any usr_symbols without a rela?
+ */
+static bool sympos_sanity_check(struct elf *klp_elf)
+{
+ bool sane = true;
+ struct sympos *sp, *aux;
+ struct section *sec;
+ struct rela *rela;
+
+ list_for_each_entry(sp, &usr_symbols, list) {
+ bool found_rela = false;
+
+ aux = list_next_entry(sp, list);
+ list_for_each_entry_from(aux, &usr_symbols, list) {
+ if (sp->pos != aux->pos &&
+ strcmp(sp->object_name, aux->object_name) == 0 &&
+ strcmp(sp->symbol_name, aux->symbol_name) == 0) {
+ WARN("Conflicting KLP_SYMPOS definition: %s.%s,%d vs. %s.%s,%d.",
+ sp->object_name, sp->symbol_name, sp->pos,
+ aux->object_name, aux->symbol_name, aux->pos);
+ sane = false;
+ }
+ }
+
+ list_for_each_entry(sec, &klp_elf->sections, list) {
+ list_for_each_entry(rela, &sec->relas, list) {
+ if (!strcmp(sp->symbol_name, rela->sym->name)) {
+ found_rela = true;
+ break;
+ }
+ }
+ }
+ if (!found_rela) {
+ //sane = false;
+ WARN("Couldn't find rela for annotated symbol: %s",
+ sp->symbol_name);
+ }
+
+
+ }
+ return sane;
+}
+
+/* Parses the livepatch elf object and fills usr_symbols */
+static bool load_usr_symbols(struct elf *klp_elf)
+{
+ char objname[MODULE_NAME_LEN];
+ struct sympos *sp;
+ struct section *sec, *relasec;
+ struct rela *rela;
+ Elf_Data converted_data;
+ struct klp_module_reloc *reloc;
+ int i, nr_entries;
+
+ list_for_each_entry(sec, &klp_elf->sections, list) {
+ if (sscanf(sec->name, ".klp.module_relocs.%55s", objname) != 1)
+ continue;
+
+ /*
+ * SYMPOS annotations are saved into arrays in
+ * .klp.module_relocs.* sections of type PROGBITS, so we
+ * need to manually translate the .sympos endianness in
+ * case we may be cross-compiling.
+ */
+ sec->elf_data->d_type = ELF_T_WORD;
+ converted_data.d_buf = sec->elf_data->d_buf;
+ converted_data.d_size = sec->elf_data->d_size;
+ converted_data.d_version = sec->elf_data->d_version;
+ gelf_xlatetom(klp_elf->elf, &converted_data, sec->elf_data,
+ elf_getident(klp_elf->elf, NULL)[EI_DATA]);
+
+ reloc = converted_data.d_buf;
+ relasec = sec->rela;
+
+ i = 0;
+ nr_entries = sec->size / sizeof(*reloc);
+ list_for_each_entry(rela, &relasec->relas, list) {
+ if (i >= nr_entries) {
+ WARN("section %s length beyond nr_entries\n",
+ relasec->name);
+ return false;
+ }
+ sp = calloc(1, sizeof(struct sympos));
+ if (!sp) {
+ WARN("Unable to allocate sympos memory\n");
+ return false;
+ }
+ sp->object_name = strdup(objname);
+ if (!sp->object_name) {
+ WARN("Unable to allocate object name\n");
+ free(sp);
+ return false;
+ }
+ sp->symbol_name = strdup(rela->sym->name);
+ if (!sp->symbol_name) {
+ WARN("Unable to allocate symbol name\n");
+ free(sp);
+ return false;
+ }
+ sp->pos = reloc[i].sympos;
+ list_add(&sp->list, &usr_symbols);
+ i++;
+ }
+ if (i != nr_entries) {
+ WARN("nr_entries mismatch (%d != %d) for %s\n",
+ i, nr_entries, relasec->name);
+ return false;
+ }
+ }
+ clear_sympos_annontations(klp_elf);
+ return sympos_sanity_check(klp_elf);
+}
+
+/* prints list of valid sympos for symbol with provided name */
+static void print_valid_module_relocs(char *name)
+{
+ struct symbol_entry *e;
+ char *cur_obj = "";
+ int counter = 0;
+ bool first = true;
+
+ /* Symbols from the same object are locally gathered in the list */
+ list_for_each_entry(e, &symbols, list) {
+ if (strcmp(e->object_name, cur_obj) != 0) {
+ cur_obj = e->object_name;
+ counter = 0;
+ }
+ if (strcmp(e->symbol_name, name) == 0) {
+ if (counter == 0) {
+ if (first) {
+ fprintf(stderr, "Valid KLP_SYMPOS for symbol %s:\n", name);
+ fprintf(stderr, "-------------------------------------------------\n");
+ } else {
+ fprintf(stderr, "}\n");
+ }
+
+ fprintf(stderr, "KLP_MODULE_RELOC(%s){\n",
+ cur_obj);
+ first = false;
+ }
+ fprintf(stderr, "\tKLP_SYMPOS(%s,%d)\n", name, counter);
+ counter++;
+ }
+ }
+ if (!first) {
+ fprintf(stderr, "}\n");
+ fprintf(stderr, "-------------------------------------------------\n");
+ }
+}
+
+/*
+ * Searches for symbol in symbols list and returns its sympos if it is unique,
+ * otherwise prints a list with all considered valid sympos
+ */
+static struct symbol_entry *find_sym_entry_by_name(char *name)
+{
+ struct symbol_entry *found = NULL;
+ struct symbol_entry *e;
+
+ list_for_each_entry(e, &symbols, list) {
+ if (strcmp(e->symbol_name, name) == 0) {
+
+ /*
+ * If there exist multiple symbols with the same
+ * name then user-provided sympos is required
+ */
+ if (found) {
+ WARN("Define KLP_SYMPOS for the symbol: %s",
+ e->symbol_name);
+
+ print_valid_module_relocs(name);
+ return NULL;
+ }
+ found = e;
+ }
+ }
+ if (found)
+ return found;
+
+ return NULL;
+}
+
+/* Checks if sympos is valid, otherwise prints valid sympos list */
+static bool valid_sympos(struct sympos *sp)
+{
+ struct symbol_entry *e;
+
+ if (sp->pos == 0) {
+
+ /*
+ * sympos of 0 is reserved for uniquely named obj:sym,
+ * verify that this is the case
+ */
+ int counter = 0;
+
+ list_for_each_entry(e, &symbols, list) {
+ if ((strcmp(e->symbol_name, sp->symbol_name) == 0) &&
+ (strcmp(e->object_name, sp->object_name) == 0)) {
+ counter++;
+ }
+ }
+ if (counter == 1)
+ return true;
+
+ WARN("Provided KLP_SYMPOS of 0, but found %d symbols matching: %s.%s,%d",
+ counter, sp->object_name, sp->symbol_name,
+ sp->pos);
+
+ } else {
+
+ /*
+ * sympos > 0 indicates a specific commonly-named obj:sym,
+ * indexing starts with 1
+ */
+ int index = 1;
+
+ list_for_each_entry(e, &symbols, list) {
+ if ((strcmp(e->symbol_name, sp->symbol_name) == 0) &&
+ (strcmp(e->object_name, sp->object_name) == 0)) {
+ if (index == sp->pos)
+ return true;
+ index++;
+ }
+ }
+
+ WARN("Provided KLP_SYMPOS does not match a symbol: %s.%s,%d",
+ sp->object_name, sp->symbol_name, sp->pos);
+ }
+
+ print_valid_module_relocs(sp->symbol_name);
+
+ return false;
+}
+
+/*
+ * Add this symbol to the converted_symbols list to cache its sympos and
+ * for later renaming.
+ */
+static bool remember_sympos(struct symbol *s, struct sympos *sp)
+{
+ struct converted_sym *cs;
+
+ cs = calloc(1, sizeof(*cs));
+ if (!cs) {
+ WARN("Unable to allocate converted_symbol entry");
+ return false;
+ }
+
+ cs->symbol = s;
+ cs->sympos = *sp;
+ list_add(&cs->list, &converted_symbols);
+
+ return true;
+}
+
+/* Returns the right sympos respective to a symbol to be relocated */
+static bool find_sympos(struct symbol *s, struct sympos *sp)
+{
+ struct symbol_entry *entry;
+ struct converted_sym *cs;
+
+ /* did we already convert this symbol? */
+ list_for_each_entry(cs, &converted_symbols, list) {
+ if (cs->symbol == s) {
+ *sp = cs->sympos;
+ return true;
+ }
+ }
+
+ /* did the user specified via annotation? */
+ if (get_usr_sympos(s, sp)) {
+ if (valid_sympos(sp)) {
+ remember_sympos(s, sp);
+ return true;
+ }
+ return false;
+ }
+
+ /* search symbol in symbols list */
+ entry = find_sym_entry_by_name(s->name);
+ if (entry) {
+ sp->symbol_name = entry->symbol_name;
+ sp->object_name = entry->object_name;
+ sp->pos = 0;
+ remember_sympos(s, sp);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * Finds or creates a klp rela section based on another given section (@oldsec)
+ * and sympos (@*sp), then returns it
+ */
+static struct section *get_or_create_klp_rela_section(struct section *oldsec,
+ struct sympos *sp, struct elf *klp_elf)
+{
+ char *name;
+ struct section *sec;
+ unsigned int length;
+
+ length = strlen(KLP_RELA_PREFIX) + strlen(sp->object_name)
+ + strlen(oldsec->base->name) + 2;
+
+ name = calloc(1, length);
+ if (!name) {
+ WARN("Memory allocation failed (%s%s.%s)\n", KLP_RELA_PREFIX,
+ sp->object_name, oldsec->base->name);
+ return NULL;
+ }
+
+ if (snprintf(name, length, KLP_RELA_PREFIX "%s.%s", sp->object_name,
+ oldsec->base->name) >= length) {
+ WARN("Length error (%s)", name);
+ free(name);
+ return NULL;
+ }
+
+ sec = find_section_by_name(klp_elf, name);
+ if (!sec)
+ sec = create_rela_section(klp_elf, name, oldsec->base);
+
+ if (sec)
+ sec->sh.sh_flags |= SHF_RELA_LIVEPATCH;
+
+ free(name);
+ return sec;
+}
+
+/* Converts rela symbol names */
+static bool convert_symbol(struct symbol *s, struct sympos *sp)
+{
+ char *name;
+ char pos[4]; /* assume that pos will never be > 999 */
+ unsigned int length;
+
+ if (snprintf(pos, sizeof(pos), "%d", sp->pos) > sizeof(pos)) {
+ WARN("Insufficient buffer for expanding sympos (%s.%s,%d)\n",
+ sp->object_name, sp->symbol_name, sp->pos);
+ return false;
+ }
+
+ length = strlen(KLP_SYM_PREFIX) + strlen(sp->object_name)
+ + strlen(sp->symbol_name) + sizeof(pos) + 3;
+
+ name = calloc(1, length);
+ if (!name) {
+ WARN("Memory allocation failed (%s%s.%s,%s)\n", KLP_SYM_PREFIX,
+ sp->object_name, sp->symbol_name, pos);
+ return false;
+ }
+
+ if (snprintf(name, length, KLP_SYM_PREFIX "%s.%s,%s", sp->object_name,
+ sp->symbol_name, pos) >= length) {
+
+ WARN("Length error (%s%s.%s,%s)", KLP_SYM_PREFIX,
+ sp->object_name, sp->symbol_name, pos);
+ free(name);
+ return false;
+ }
+
+ /*
+ * Despite the memory waste, we don't mind freeing the original symbol
+ * name memory chunk. Keeping it there is harmless and, since removing
+ * bytes from the string section is non-trivial, it is unworthy.
+ */
+ s->name = name;
+ s->sec = NULL;
+ s->sym.st_name = -1;
+ s->sym.st_shndx = SHN_LIVEPATCH;
+
+ return true;
+}
+
+/* Checks if a rela was converted */
+static bool is_converted_rela(struct rela *rela)
+{
+ return !!rela->klp_rela_sec;
+}
+
+/*
+ * Convert rela that cannot be resolved by the classic module loader
+ * to the special klp rela one.
+ */
+static bool convert_rela(struct section *oldsec, struct rela *rela,
+ struct sympos *sp, struct elf *klp_elf)
+{
+ struct section *sec;
+
+ sec = get_or_create_klp_rela_section(oldsec, sp, klp_elf);
+ if (!sec) {
+ WARN("Can't create or access klp.rela section (%s.%s)\n",
+ sp->object_name, sp->symbol_name);
+ return false;
+ }
+
+ rela->klp_rela_sec = sec;
+
+ return true;
+}
+
+static void move_rela(struct rela *r)
+{
+ /* Move the converted rela to klp rela section */
+ list_del(&r->list);
+ list_add_tail(&r->list, &r->klp_rela_sec->relas);
+}
+
+/* Checks if given symbol name matches a symbol in exp_symbols */
+static bool is_exported(char *sname)
+{
+ struct symbol_entry *e;
+
+ /*
+ * exp_symbols itens are prefixed with __ksymtab_ - comparisons must
+ * skip prefix and check if both are properly null-terminated
+ */
+ list_for_each_entry(e, &exp_symbols, list) {
+ if (strcmp(e->symbol_name + 10, sname) == 0)
+ return true;
+ }
+ return false;
+}
+
+/* Checks if symbol should be skipped */
+static bool skip_symbol(struct symbol *sym)
+{
+ /* already resolved? */
+ if (sym->sec)
+ return true;
+
+ /* skip symbol with index 0 */
+ if (!sym->idx)
+ return true;
+
+ /* we should not touch .TOC. on ppc64le */
+ if (strcmp(sym->name, ".TOC.") == 0)
+ return true;
+
+ if (is_exported(sym->name))
+ return true;
+
+ return false;
+}
+
+/* Checks if a section is a klp rela section */
+static bool is_klp_rela_section(char *sname)
+{
+ int len = strlen(KLP_RELA_PREFIX);
+
+ if (strncmp(sname, KLP_RELA_PREFIX, len) == 0)
+ return true;
+ return false;
+}
+
+/*
+ * Frees the list, new names and rela sections as created by
+ * remember_sympos(), convert_rela(), and convert_symbol()
+ */
+static void free_converted_resources(struct elf *klp_elf)
+{
+ struct converted_sym *cs, *cs_aux;
+ struct section *sec;
+
+ list_for_each_entry_safe(cs, cs_aux, &converted_symbols, list) {
+ free(cs->symbol->name);
+ free(cs);
+ }
+
+ list_for_each_entry(sec, &klp_elf->sections, list) {
+ if (is_klp_rela_section(sec->name)) {
+ free(sec->elf_data);
+ free(sec->name);
+ }
+ }
+}
+
+/*
+ * Checks if section may be skipped (conditions)
+ */
+static bool skip_section(struct section *sec)
+{
+ if (!is_rela_section(sec))
+ return true;
+
+ if (is_klp_rela_section(sec->name))
+ return true;
+
+ return false;
+}
+
+/*
+ * Checks if rela conversion is supported in given section
+ */
+static bool supported_section(struct section *sec, char *object_name)
+{
+#if 0
+ /*
+ * klp-relocations forbidden in sections that otherwise would
+ * match in allowed_prefixes[]
+ */
+ static const char * const not_allowed[] = {
+ ".rela.data.rel.ro",
+ ".rela.data.rel.ro.local",
+ ".rela.data..ro_after_init",
+ NULL
+ };
+#endif
+
+ /* klp-relocations allowed in sections only for vmlinux */
+ static const char * const allowed_vmlinux[] = {
+ ".rela__jump_table",
+ NULL
+ };
+
+ /* klp-relocations allowed in sections with prefixes */
+ static const char * const allowed_prefixes[] = {
+ ".rela.data",
+ ".rela.rodata", // supported ???
+ ".rela.sdata",
+ ".rela.text",
+ ".rela.toc",
+ NULL
+ };
+
+ const char * const *name;
+
+#if 0
+ for (name = not_allowed; *name; name++)
+ if (strcmp(sec->name, *name) == 0)
+ return false;
+#endif
+
+ if (strcmp(object_name, "vmlinux") == 0) {
+ for (name = allowed_vmlinux; *name; name++)
+ if (strcmp(sec->name, *name) == 0)
+ return true;
+ }
+
+ for (name = allowed_prefixes; *name; name++)
+ if (strncmp(sec->name, *name, strlen(*name)) == 0)
+ return true;
+
+ return false;
+}
+
+int main(int argc, const char **argv)
+{
+ const char *klp_in_module, *klp_out_module, *symbols_list;
+ struct rela *rela, *tmprela;
+ struct section *sec;
+ struct sympos sp;
+ struct elf *klp_elf;
+ struct converted_sym *cs;
+ int errors = 0;
+
+ if (argc != 4) {
+ WARN("Usage: %s <symbols.klp> <input.ko> <output.ko>", argv[0]);
+ return -1;
+ }
+
+ symbols_list = argv[1];
+ klp_in_module = argv[2];
+ klp_out_module = argv[3];
+
+ klp_elf = elf_open(klp_in_module);
+ if (!klp_elf) {
+ WARN("Unable to read elf file %s\n", klp_in_module);
+ return -1;
+ }
+
+ if (!load_syms_lists(symbols_list))
+ return -1;
+
+ if (!load_usr_symbols(klp_elf)) {
+ WARN("Unable to load user-provided sympos");
+ return -1;
+ }
+
+ list_for_each_entry(sec, &klp_elf->sections, list) {
+ if (skip_section(sec))
+ continue;
+
+ list_for_each_entry(rela, &sec->relas, list) {
+ if (skip_symbol(rela->sym))
+ continue;
+
+ /* rela needs to be converted */
+
+ if (!find_sympos(rela->sym, &sp)) {
+ WARN("Unable to find missing symbol: %s",
+ rela->sym->name);
+ errors++;
+ continue;
+ }
+ if (!supported_section(sec, sp.object_name)) {
+ WARN("Conversion not supported for symbol: %s section: %s object: %s",
+ rela->sym->name, sec->name,
+ sp.object_name);
+ errors++;
+ continue;
+ }
+ if (!convert_rela(sec, rela, &sp, klp_elf)) {
+ WARN("Unable to convert relocation: %s",
+ rela->sym->name);
+ return -1;
+ }
+ }
+
+ if (errors)
+ return -1;
+
+ /* Now move all converted relas in list-safe manner */
+ list_for_each_entry_safe(rela, tmprela, &sec->relas, list) {
+ if (is_converted_rela(rela))
+ move_rela(rela);
+ }
+ }
+
+ /* Rename the converted symbols */
+ list_for_each_entry(cs, &converted_symbols, list) {
+ if (!convert_symbol(cs->symbol, &cs->sympos)) {
+ WARN("Unable to convert symbol name (%s)\n",
+ cs->symbol->name);
+ return -1;
+ }
+ }
+
+ free_syms_lists();
+ if (elf_write_file(klp_elf, klp_out_module))
+ return -1;
+
+ free_converted_resources(klp_elf);
+ elf_close(klp_elf);
+
+ return 0;
+}
+
+/* Functions kept commented since they might be useful for future debugging */
+
+/* Dumps sympos list (useful for debugging purposes)
+ * static void dump_sympos(void)
+ * {
+ * struct sympos *sp;
+ *
+ * fprintf(stderr, "BEGIN OF SYMPOS DUMP\n");
+ * list_for_each_entry(sp, &usr_symbols, list) {
+ * fprintf(stderr, "%s %s %d\n", sp->symbol_name, sp->object_name,
+ * sp->pos);
+ * }
+ * fprintf(stderr, "END OF SYMPOS DUMP\n");
+ * }
+ *
+ *
+ * / Dump symbols list for debugging purposes /
+ * static void dump_symbols(void)
+ * {
+ * struct symbol_entry *entry;
+ *
+ * fprintf(stderr, "BEGIN OF SYMBOLS DUMP\n");
+ * list_for_each_entry(entry, &symbols, list)
+ * printf("%s %s\n", entry->object_name, entry->symbol_name);
+ * fprintf(stderr, "END OF SYMBOLS DUMP\n");
+ * }
+ */
diff --git a/scripts/livepatch/klp-convert.h b/scripts/livepatch/klp-convert.h
new file mode 100644
index 000000000000..35b9dc4e32c4
--- /dev/null
+++ b/scripts/livepatch/klp-convert.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2016 Josh Poimboeuf <jpoimboe@redhat.com>
+ * Copyright (C) 2017 Joao Moreira <jmoreira@suse.de>
+ *
+ */
+
+#define SHN_LIVEPATCH 0xff20
+#define SHF_RELA_LIVEPATCH 0x00100000
+#define MODULE_NAME_LEN (64 - sizeof(GElf_Addr))
+#define WARN(format, ...) \
+ fprintf(stderr, "klp-convert: " format "\n", ##__VA_ARGS__)
+
+struct symbol_entry {
+ struct list_head list;
+ char *symbol_name;
+ char *object_name;
+};
+
+struct sympos {
+ struct list_head list;
+ char *symbol_name;
+ char *object_name;
+ int pos;
+};
+
+/*
+ * klp-convert uses macros and structures defined in the linux sources
+ * package (see include/uapi/linux/livepatch.h). To prevent the
+ * dependency when building locally, they are defined below. Also notice
+ * that these should match the definitions from the targeted kernel.
+ */
+
+#define KLP_RELA_PREFIX ".klp.rela."
+#define KLP_SYM_PREFIX ".klp.sym."
+
+#ifndef __packed
+#define __packed __attribute__((packed))
+#endif
+
+struct klp_module_reloc {
+ union {
+ void *sym;
+ uint64_t sym64; /* Force 64-bit width */
+ };
+ uint32_t sympos;
+} __packed;
diff --git a/scripts/livepatch/list.h b/scripts/livepatch/list.h
new file mode 100644
index 000000000000..4d429120fabf
--- /dev/null
+++ b/scripts/livepatch/list.h
@@ -0,0 +1,391 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_LIST_H
+#define _LINUX_LIST_H
+
+/*
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when
+ * manipulating whole lists rather than single entries, as
+ * sometimes we already know the next/prev entries and we can
+ * generate better code by using them directly rather than
+ * using the generic single-entry routines.
+ */
+
+#define WRITE_ONCE(a, b) (a = b)
+#define READ_ONCE(a) a
+
+#undef offsetof
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr: the pointer to the member.
+ * @type: the type of the container struct this is embedded in.
+ * @member: the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({ \
+ const typeof(((type *)0)->member) * __mptr = (ptr); \
+ (type *)((char *)__mptr - offsetof(type, member)); })
+
+struct list_head {
+ struct list_head *next, *prev;
+};
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+ struct list_head name = LIST_HEAD_INIT(name)
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+ WRITE_ONCE(list->next, list);
+ list->prev = list;
+}
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add(struct list_head *new,
+ struct list_head *prev,
+ struct list_head *next)
+{
+ next->prev = new;
+ new->next = next;
+ new->prev = prev;
+ WRITE_ONCE(prev->next, new);
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+ __list_add(new, head, head->next);
+}
+
+
+/**
+ * list_add_tail - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+ __list_add(new, head->prev, head);
+}
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head *prev, struct list_head *next)
+{
+ next->prev = prev;
+ WRITE_ONCE(prev->next, next);
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void __list_del_entry(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+}
+
+static inline void list_del(struct list_head *entry)
+{
+ __list_del(entry->prev, entry->next);
+}
+
+/**
+ * list_is_last - tests whether @list is the last entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_last(const struct list_head *list,
+ const struct list_head *head)
+{
+ return list->next == head;
+}
+
+/**
+ * list_empty - tests whether a list is empty
+ * @head: the list to test.
+ */
+static inline int list_empty(const struct list_head *head)
+{
+ return READ_ONCE(head->next) == head;
+}
+
+/**
+ * list_entry - get the struct for this entry
+ * @ptr: the &struct list_head pointer.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_entry(ptr, type, member) \
+ container_of(ptr, type, member)
+
+/**
+ * list_first_entry - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+ list_entry((ptr)->next, type, member)
+
+/**
+ * list_last_entry - get the last element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_last_entry(ptr, type, member) \
+ list_entry((ptr)->prev, type, member)
+
+/**
+ * list_first_entry_or_null - get the first element from a list
+ * @ptr: the list head to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_first_entry_or_null(ptr, type, member) \
+ (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+
+/**
+ * list_next_entry - get the next element in list
+ * @pos: the type * to cursor
+ * @member: the name of the list_head within the struct.
+ */
+#define list_next_entry(pos, member) \
+ list_entry((pos)->member.next, typeof(*(pos)), member)
+
+/**
+ * list_prev_entry - get the prev element in list
+ * @pos: the type * to cursor
+ * @member: the name of the list_head within the struct.
+ */
+#define list_prev_entry(pos, member) \
+ list_entry((pos)->member.prev, typeof(*(pos)), member)
+
+/**
+ * list_for_each - iterate over a list
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ */
+#define list_for_each(pos, head) \
+ for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * list_for_each_prev - iterate over a list backwards
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+ for (pos = (head)->prev; pos != (head); pos = pos->prev)
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
+ */
+#define list_for_each_safe(pos, n, head) \
+ for (pos = (head)->next, n = pos->next; pos != (head); \
+ pos = n, n = pos->next)
+
+/**
+ * list_for_each_prev_safe - iterate over a list backwards safe against removal
+ of list entry
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @n: another &struct list_head to use as temporary storage
+ * @head: the head for your list.
+ */
+#define list_for_each_prev_safe(pos, n, head) \
+ for (pos = (head)->prev, n = pos->prev; \
+ pos != (head); \
+ pos = n, n = pos->prev)
+
+/**
+ * list_for_each_entry - iterate over list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_for_each_entry(pos, head, member) \
+ for (pos = list_first_entry(head, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member) \
+ for (pos = list_last_entry(head, typeof(*pos), member); \
+ &pos->member != (head); \
+ pos = list_prev_entry(pos, member))
+
+/**
+ * list_prepare_entry - prepare a pos entry for use in
+ list_for_each_entry_continue()
+ * @pos: the type * to use as a start point
+ * @head: the head of the list
+ * @member: the name of the list_head within the struct.
+ *
+ * Prepares a pos entry for use as a start point in
+ list_for_each_entry_continue().
+ */
+#define list_prepare_entry(pos, head, member) \
+ ((pos) ? : list_entry(head, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue - continue iteration over list of given type
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue(pos, head, member) \
+ for (pos = list_next_entry(pos, member); \
+ &pos->member != (head); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_continue_reverse - iterate backwards from the given point
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Start to iterate over list of given type backwards, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_reverse(pos, head, member) \
+ for (pos = list_prev_entry(pos, member); \
+ &pos->member != (head); \
+ pos = list_prev_entry(pos, member))
+
+/**
+ * list_for_each_entry_from - iterate over list of given type from the current
+ point
+ * @pos: the type * to use as a loop cursor.
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member) \
+ for (; &pos->member != (head); \
+ pos = list_next_entry(pos, member))
+
+/**
+ * list_for_each_entry_safe - iterate over list of given type safe against
+ removal of list entry
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member) \
+ for (pos = list_first_entry(head, typeof(*pos), member), \
+ n = list_next_entry(pos, member); \
+ &pos->member != (head); \
+ pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_continue - continue list iteration safe against
+ * removal
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Iterate over list of given type, continuing after current point,
+ * safe against removal of list entry.
+ */
+#define list_for_each_entry_safe_continue(pos, n, head, member) \
+ for (pos = list_next_entry(pos, member), \
+ n = list_next_entry(pos, member); \
+ &pos->member != (head); \
+ pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_from - iterate over list from current point safe
+ * against removal
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Iterate over list of given type from current point, safe against
+ * removal of list entry.
+ */
+#define list_for_each_entry_safe_from(pos, n, head, member) \
+ for (n = list_next_entry(pos, member); \
+ &pos->member != (head); \
+ pos = n, n = list_next_entry(n, member))
+
+/**
+ * list_for_each_entry_safe_reverse - iterate backwards over list safe against
+ * removal
+ * @pos: the type * to use as a loop cursor.
+ * @n: another type * to use as temporary storage
+ * @head: the head for your list.
+ * @member: the name of the list_head within the struct.
+ *
+ * Iterate backwards over list of given type, safe against removal
+ * of list entry.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member) \
+ for (pos = list_last_entry(head, typeof(*pos), member), \
+ n = list_prev_entry(pos, member); \
+ &pos->member != (head); \
+ pos = n, n = list_prev_entry(n, member))
+
+/**
+ * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
+ * @pos: the loop cursor used in the list_for_each_entry_safe loop
+ * @n: temporary storage used in list_for_each_entry_safe
+ * @member: the name of the list_head within the struct.
+ *
+ * list_safe_reset_next is not safe to use in general if the list may be
+ * modified concurrently (eg. the lock is dropped in the loop body). An
+ * exception to this is if the cursor element (pos) is pinned in the list,
+ * and list_safe_reset_next is called after re-taking the lock and before
+ * completing the current iteration of the loop body.
+ */
+#define list_safe_reset_next(pos, n, member) \
+ (n = list_next_entry(pos, member))
+
+#endif
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
@ 2022-02-16 16:46 ` Joe Lawrence
2022-02-16 16:56 ` Joe Lawrence
` (2 subsequent siblings)
3 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:46 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:31AM -0500, Joe Lawrence wrote:
>
> [ ... snip ... ]
>
> +/*
> + * Checks if rela conversion is supported in given section
> + */
> +static bool supported_section(struct section *sec, char *object_name)
> +{
> +#if 0
> + /*
> + * klp-relocations forbidden in sections that otherwise would
> + * match in allowed_prefixes[]
> + */
> + static const char * const not_allowed[] = {
> + ".rela.data.rel.ro",
> + ".rela.data.rel.ro.local",
> + ".rela.data..ro_after_init",
> + NULL
> + };
> +#endif
> +
> + /* klp-relocations allowed in sections only for vmlinux */
> + static const char * const allowed_vmlinux[] = {
> + ".rela__jump_table",
> + NULL
> + };
> +
> + /* klp-relocations allowed in sections with prefixes */
> + static const char * const allowed_prefixes[] = {
> + ".rela.data",
> + ".rela.rodata", // supported ???
> + ".rela.sdata",
> + ".rela.text",
> + ".rela.toc",
> + NULL
> + };
> +
> + const char * const *name;
> +
> +#if 0
> + for (name = not_allowed; *name; name++)
> + if (strcmp(sec->name, *name) == 0)
> + return false;
> +#endif
I wasn't sure if relocations in .rela.<read-only> sections should be
supported or not, particularly in the late relocation use case. For
most, I think they can be easily avoided by the livepatch author
changing the storage class for the C pointer that is relocated. On the
other hand, this may be disruptive to automated tools like
kpatch-build... or maybe there is no issue at all for late relocating
.rela.<read-only>?
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
2022-02-16 16:46 ` Joe Lawrence
@ 2022-02-16 16:56 ` Joe Lawrence
2022-04-14 15:03 ` elf API: was: " Petr Mladek
2023-02-06 18:16 ` Marcos Paulo de Souza
3 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:56 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:31AM -0500, Joe Lawrence wrote:
> diff --git a/include/uapi/linux/livepatch.h b/include/uapi/linux/livepatch.h
> index e19430918a07..2ee98e985c2a 100644
> --- a/include/uapi/linux/livepatch.h
> +++ b/include/uapi/linux/livepatch.h
> @@ -9,7 +9,17 @@
> #ifndef _UAPI_LIVEPATCH_H
> #define _UAPI_LIVEPATCH_H
>
> +#include <linux/types.h>
> +
> #define KLP_RELA_PREFIX ".klp.rela."
> #define KLP_SYM_PREFIX ".klp.sym."
>
> +struct klp_module_reloc {
> + union {
> + void *sym;
> + __u64 sym64; /* Force 64-bit width */
> + };
> + __u32 sympos;
> +} __packed;
> +
>
> [ ... snip ... ]
>
> diff --git a/scripts/livepatch/klp-convert.h b/scripts/livepatch/klp-convert.h
> new file mode 100644
> index 000000000000..35b9dc4e32c4
> --- /dev/null
> +++ b/scripts/livepatch/klp-convert.h
>
> [ ... snip ... ]
>
> +struct klp_module_reloc {
> + union {
> + void *sym;
> + uint64_t sym64; /* Force 64-bit width */
> + };
> + uint32_t sympos;
> +} __packed;
This was a hack I added to force a consistent width for the symbol
pointer in case the user was building for 32-bit. The actual void
*sym64 value itself is not so interesting as it's only needed for the
compiler to create a relocation (later resolved by klp-convert). That
said, sympos is used by klp-convert, and I bet it's not endian-safe
here.
Better suggestions welcome :)
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread* elf API: was: Re: [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
2022-02-16 16:46 ` Joe Lawrence
2022-02-16 16:56 ` Joe Lawrence
@ 2022-04-14 15:03 ` Petr Mladek
2022-04-18 18:01 ` Joe Lawrence
2023-02-06 18:16 ` Marcos Paulo de Souza
3 siblings, 1 reply; 28+ messages in thread
From: Petr Mladek @ 2022-04-14 15:03 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed 2022-02-16 11:39:31, Joe Lawrence wrote:
> From: Josh Poimboeuf <jpoimboe@redhat.com>
> klp-convert relies on libelf and on a list implementation. Add files
> scripts/livepatch/elf.c and scripts/livepatch/elf.h, which are a libelf
> interfacing layer and scripts/livepatch/list.h, which is a list
> implementation.
>
> --- /dev/null
> +++ b/scripts/livepatch/elf.c
> +static int update_shstrtab(struct elf *elf)
> +{
> + struct section *shstrtab, *sec;
> + size_t orig_size, new_size = 0, offset, len;
> + char *buf;
> +
> + shstrtab = find_section_by_name(elf, ".shstrtab");
> + if (!shstrtab) {
> + WARN("can't find .shstrtab");
> + return -1;
> + }
> +
> + orig_size = new_size = shstrtab->size;
> +
> + list_for_each_entry(sec, &elf->sections, list) {
> + if (sec->sh.sh_name != -1)
> + continue;
> + new_size += strlen(sec->name) + 1;
> + }
> +
> + if (new_size == orig_size)
> + return 0;
> +
> + buf = malloc(new_size);
> + if (!buf) {
> + WARN("malloc failed");
> + return -1;
> + }
> + memcpy(buf, (void *)shstrtab->data, orig_size);
> +
> + offset = orig_size;
> + list_for_each_entry(sec, &elf->sections, list) {
> + if (sec->sh.sh_name != -1)
> + continue;
> + sec->sh.sh_name = offset;
> + len = strlen(sec->name) + 1;
> + memcpy(buf + offset, sec->name, len);
> + offset += len;
> + }
> +
> + shstrtab->elf_data->d_buf = shstrtab->data = buf;
> + shstrtab->elf_data->d_size = shstrtab->size = new_size;
> + shstrtab->sh.sh_size = new_size;
All the update_*() functions have the same pattern. They replace
the original buffer with a bigger one when needed. And the pointer
to the original buffer gets lost.
I guess that the original buffer could not be freed because
it is part of a bigger allocated blob. Or it might even be
a file mapped to memory.
It looks like a memory leak. We could probably ignore it.
But there is another related danger, see below.
> + return 1;
> +}
> +
[...]
> +int elf_write_file(struct elf *elf, const char *file)
> +{
> + int ret_shstrtab;
> + int ret_strtab;
> + int ret_symtab;
> + int ret_relas;
We do not free the bigger buffers when something goes wrong.
Also this is not that important. But it is easy to fix:
We might do:
int ret_shstrtab = 0;
int ret_strtab = 0;
int ret_symtab = 0;
int ret_relas = 0;
> + int ret;
> +
> + ret_shstrtab = update_shstrtab(elf);
> + if (ret_shstrtab < 0)
> + return ret_shstrtab;
> +
> + ret_strtab = update_strtab(elf);
> + if (ret_strtab < 0)
> + return ret_strtab;
if (ret_strtab < 0) {
ret = ret_strtab;
goto out;
}
> + ret_symtab = update_symtab(elf);
> + if (ret_symtab < 0)
> + return ret_symtab;
if (ret_symtab < 0) {
ret = ret_symtab;
goto out;
}
> + ret_relas = update_relas(elf);
> + if (ret_relas < 0)
> + return ret_relas;
if (ret_relas < 0) {
ret = ret_relas;
goto out;
}
> + update_groups(elf);
> +
> + ret = write_file(elf, file);
> + if (ret)
> + return ret;
Continue even when write_file(elf, file) returns an error.
out:
> + if (ret_relas > 0)
> + free_relas(elf);
> + if (ret_symtab > 0)
> + free_symtab(elf);
> + if (ret_strtab > 0)
> + free_strtab(elf);
> + if (ret_shstrtab > 0)
> + free_shstrtab(elf);
> +
> + return ret;
Another problem is that the free_*() functions release the
bigger buffers. But they do not put back the original ones. Also
all the updated offsets and indexes point to the bigger buffers.
As a result the structures can't be made consistent any longer.
I am not sure if there is an easy way to fix it. IMHO, proper solution
is not worth a big effort. klp-convert frees everthing after writing
the elf file.
Well, we should at least make a comment above elf_write_file() about
that the structures are damaged in this way.
Finally, my main concern:
It brings a question whether the written data were consistent.
I am not familiar with the elf format. I quess that it is rather
stable. But there might still be some differences between
architectures or some new extensions that might need special handing.
I do not see any big consistency checks in the gelf_update_ehdr(),
elf_update(), or elf_end() functions that are used when writing
the changes.
But there seems to be some thorough consistency checks provided by:
readelf --enable-checks
It currently see these warnings:
$> readelf --lint lib/livepatch/test_klp_convert2.ko >/dev/null
readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
$> readelf --lint lib/livepatch/test_klp_callbacks_mod.ko >/dev/null
readelf: Warning: Section '.data': has a size of zero - is this intended ?
readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
$> readelf --lint lib/test_printf.ko >/dev/null
readelf: Warning: Section '.text': has a size of zero - is this intended ?
readelf: Warning: Section '.data': has a size of zero - is this intended ?
readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
But I see this warnings even without this patchset. I wonder if it
might really help to find problems introduced by klp-convert or
if it would be a waste of time.
Best Regards,
Petr
^ permalink raw reply [flat|nested] 28+ messages in thread* Re: elf API: was: Re: [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-04-14 15:03 ` elf API: was: " Petr Mladek
@ 2022-04-18 18:01 ` Joe Lawrence
0 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-04-18 18:01 UTC (permalink / raw)
To: Petr Mladek; +Cc: live-patching, linux-kernel, linux-kbuild
On Thu, Apr 14, 2022 at 05:03:04PM +0200, Petr Mladek wrote:
> On Wed 2022-02-16 11:39:31, Joe Lawrence wrote:
> > From: Josh Poimboeuf <jpoimboe@redhat.com>
> > klp-convert relies on libelf and on a list implementation. Add files
> > scripts/livepatch/elf.c and scripts/livepatch/elf.h, which are a libelf
> > interfacing layer and scripts/livepatch/list.h, which is a list
> > implementation.
> >
> > --- /dev/null
> > +++ b/scripts/livepatch/elf.c
> > +static int update_shstrtab(struct elf *elf)
> > +{
> > + struct section *shstrtab, *sec;
> > + size_t orig_size, new_size = 0, offset, len;
> > + char *buf;
> > +
> > + shstrtab = find_section_by_name(elf, ".shstrtab");
> > + if (!shstrtab) {
> > + WARN("can't find .shstrtab");
> > + return -1;
> > + }
> > +
> > + orig_size = new_size = shstrtab->size;
> > +
> > + list_for_each_entry(sec, &elf->sections, list) {
> > + if (sec->sh.sh_name != -1)
> > + continue;
> > + new_size += strlen(sec->name) + 1;
> > + }
> > +
> > + if (new_size == orig_size)
> > + return 0;
> > +
> > + buf = malloc(new_size);
> > + if (!buf) {
> > + WARN("malloc failed");
> > + return -1;
> > + }
> > + memcpy(buf, (void *)shstrtab->data, orig_size);
> > +
> > + offset = orig_size;
> > + list_for_each_entry(sec, &elf->sections, list) {
> > + if (sec->sh.sh_name != -1)
> > + continue;
> > + sec->sh.sh_name = offset;
> > + len = strlen(sec->name) + 1;
> > + memcpy(buf + offset, sec->name, len);
> > + offset += len;
> > + }
> > +
> > + shstrtab->elf_data->d_buf = shstrtab->data = buf;
> > + shstrtab->elf_data->d_size = shstrtab->size = new_size;
> > + shstrtab->sh.sh_size = new_size;
>
> All the update_*() functions have the same pattern. They replace
> the original buffer with a bigger one when needed. And the pointer
> to the original buffer gets lost.
>
> I guess that the original buffer could not be freed because
> it is part of a bigger allocated blob. Or it might even be
> a file mapped to memory.
>
> It looks like a memory leak. We could probably ignore it.
> But there is another related danger, see below.
>
Hi Petr,
Looking at this code, I would agree that it looks very suspicious with
respect to leaking memory. Then I remembered that I had been testing
with valgrind and it hadn't reported any lost allocations.
I was confused, so to verify, I fired up gdb with conditional
breakpoints (when the passed pointer was one of the clobbered X-Y->d_buf
pointers) on glibc's __GI___libc_free() and found that these buffers
were all handled by libelf's elf_end() function:
/* The section data is allocated if we couldn't mmap
the file. */
if (elf->map_address == NULL)
free (scn->rawdata_base);
The program, in the name of efficiency or developer expediency (I dunno,
I didn't create it), ends up creating a few file representations:
1) libelf's internal representation of the input ELF file
2) klp-convert's structures (see elf.h)
a) derived from the previous (1)
b) modified for klp-relocations
3) klp-convert's new Elf structure for the output ELF file (see
write_file())
a) information from (2b) is used to create consistent structures
And so representation (2) ends up with some data values (enums, etc.)
from (1) which is OK. In a few places, however, it copies the buffer
pointers from (1)... and then as you noticed, may need to realloc them
for step (2b). Now buffer ownership is muddled and depends on the
runtime situation.
Do you think it would be worth some refactoring to try and keep library
and program allocated memory separate? In cases where klp-convert only
needs to read memory, perhaps a naming or scoping convention could help.
For those re-allocations, I can't think of anything clever aside from
separate buffers or noting original (ie, library) pointer values.
> > + return 1;
> > +}
> > +
>
> [...]
>
> > +int elf_write_file(struct elf *elf, const char *file)
> > +{
> > + int ret_shstrtab;
> > + int ret_strtab;
> > + int ret_symtab;
> > + int ret_relas;
>
> We do not free the bigger buffers when something goes wrong.
> Also this is not that important. But it is easy to fix:
>
> We might do:
>
> int ret_shstrtab = 0;
> int ret_strtab = 0;
> int ret_symtab = 0;
> int ret_relas = 0;
>
> > + int ret;
> > +
> > + ret_shstrtab = update_shstrtab(elf);
> > + if (ret_shstrtab < 0)
> > + return ret_shstrtab;
> > +
> > + ret_strtab = update_strtab(elf);
> > + if (ret_strtab < 0)
> > + return ret_strtab;
>
> if (ret_strtab < 0) {
> ret = ret_strtab;
> goto out;
> }
>
> > + ret_symtab = update_symtab(elf);
> > + if (ret_symtab < 0)
> > + return ret_symtab;
>
> if (ret_symtab < 0) {
> ret = ret_symtab;
> goto out;
> }
>
> > + ret_relas = update_relas(elf);
> > + if (ret_relas < 0)
> > + return ret_relas;
>
> if (ret_relas < 0) {
> ret = ret_relas;
> goto out;
> }
>
>
> > + update_groups(elf);
> > +
> > + ret = write_file(elf, file);
> > + if (ret)
> > + return ret;
>
> Continue even when write_file(elf, file) returns an error.
>
> out:
>
> > + if (ret_relas > 0)
> > + free_relas(elf);
> > + if (ret_symtab > 0)
> > + free_symtab(elf);
> > + if (ret_strtab > 0)
> > + free_strtab(elf);
> > + if (ret_shstrtab > 0)
> > + free_shstrtab(elf);
> > +
> > + return ret;
Yes, that's a good recommendation. I think this would improve the error
handling and isn't too hard to implement.
> Another problem is that the free_*() functions release the
> bigger buffers. But they do not put back the original ones. Also
> all the updated offsets and indexes point to the bigger buffers.
> As a result the structures can't be made consistent any longer.
>
> I am not sure if there is an easy way to fix it. IMHO, proper solution
> is not worth a big effort. klp-convert frees everthing after writing
> the elf file.
>
> Well, we should at least make a comment above elf_write_file() about
> that the structures are damaged in this way.
The assumption in the code seems to be that elf_write_file() and the
update_*() functions it calls would only ever be done once.
And then, I think, that the new output file Elf structure created by
write_file() and passed to elf_update(), would have consistent offset
and indexes since the klp-converted structures are iterated in order as
appropriate gelf_update_*() are called.
If something else looks amiss, please point it out and I can try to
verify using my tests.
> Finally, my main concern:
>
> It brings a question whether the written data were consistent.
>
> I am not familiar with the elf format. I quess that it is rather
> stable. But there might still be some differences between
> architectures or some new extensions that might need special handing.
>
> I do not see any big consistency checks in the gelf_update_ehdr(),
> elf_update(), or elf_end() functions that are used when writing
> the changes.
If you have specifics in mind, I can verify empirically and research
if/how libelf abstracts this for us or not (endianness in cross-arch
scenarios, for example).
> But there seems to be some thorough consistency checks provided by:
>
> readelf --enable-checks
>
> It currently see these warnings:
>
> $> readelf --lint lib/livepatch/test_klp_convert2.ko >/dev/null
> readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
>
> $> readelf --lint lib/livepatch/test_klp_callbacks_mod.ko >/dev/null
> readelf: Warning: Section '.data': has a size of zero - is this intended ?
> readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
>
> $> readelf --lint lib/test_printf.ko >/dev/null
> readelf: Warning: Section '.text': has a size of zero - is this intended ?
> readelf: Warning: Section '.data': has a size of zero - is this intended ?
> readelf: Warning: Section '.note.GNU-stack': has a size of zero - is this intended ?
>
> But I see this warnings even without this patchset. I wonder if it
> might really help to find problems introduced by klp-convert or
> if it would be a waste of time.
Interesting, I didn't know about readelf --enable-checks / --lint. Do
you know if this is any different from elflint?
In any case, I can take a look at those, but as you noticed, it looks
like all of the complaints also crop up outside of klp-convert cases. I
wonder if kernel linker script is unconditionally creating those
zero-sized sections?
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread
* Re: [RFC PATCH v6 03/12] livepatch: Add klp-convert tool
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
` (2 preceding siblings ...)
2022-04-14 15:03 ` elf API: was: " Petr Mladek
@ 2023-02-06 18:16 ` Marcos Paulo de Souza
3 siblings, 0 replies; 28+ messages in thread
From: Marcos Paulo de Souza @ 2023-02-06 18:16 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:31AM -0500, Joe Lawrence wrote:
> From: Josh Poimboeuf <jpoimboe@redhat.com>
All the comments bellow are suggestions. Besides them being addressed or not:
Reviewed-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> +
> +/*
> + * User provided sympos annotation checks:
> + * - do two or more elements in usr_symbols have the same object and
> + * name, but different symbol position
> + * - are there any usr_symbols without a rela?
> + */
> +static bool sympos_sanity_check(struct elf *klp_elf)
> +{
> + bool sane = true;
> + struct sympos *sp, *aux;
> + struct section *sec;
> + struct rela *rela;
> +
> + list_for_each_entry(sp, &usr_symbols, list) {
> + bool found_rela = false;
> +
> + aux = list_next_entry(sp, list);
> + list_for_each_entry_from(aux, &usr_symbols, list) {
> + if (sp->pos != aux->pos &&
> + strcmp(sp->object_name, aux->object_name) == 0 &&
> + strcmp(sp->symbol_name, aux->symbol_name) == 0) {
> + WARN("Conflicting KLP_SYMPOS definition: %s.%s,%d vs. %s.%s,%d.",
> + sp->object_name, sp->symbol_name, sp->pos,
> + aux->object_name, aux->symbol_name, aux->pos);
The WARN message could be simplified by mentioning the different position,
something like:
WARN("Conflicting KLP_SYMPOS definition: %s.%s %d vs. %d.",
sp->object_name, sp->symbol_name, sp->pos aux->pos);
> + sane = false;
> + }
> + }
> +
> + list_for_each_entry(sec, &klp_elf->sections, list) {
> + list_for_each_entry(rela, &sec->relas, list) {
> + if (!strcmp(sp->symbol_name, rela->sym->name)) {
> + found_rela = true;
> + break;
> + }
> + }
> + }
> + if (!found_rela) {
> + //sane = false;
At this point I believe that sane should be assigned to false to help the user
to know that the specified symbol isn't being used in the livepatch.
> + WARN("Couldn't find rela for annotated symbol: %s",
> + sp->symbol_name);
> + }
> +
> +
> + }
> + return sane;
> +}
<snip>
> +/*
> + * Searches for symbol in symbols list and returns its sympos if it is unique,
> + * otherwise prints a list with all considered valid sympos
> + */
> +static struct symbol_entry *find_sym_entry_by_name(char *name)
> +{
> + struct symbol_entry *found = NULL;
> + struct symbol_entry *e;
> +
> + list_for_each_entry(e, &symbols, list) {
> + if (strcmp(e->symbol_name, name) == 0) {
> +
> + /*
> + * If there exist multiple symbols with the same
> + * name then user-provided sympos is required
> + */
> + if (found) {
> + WARN("Define KLP_SYMPOS for the symbol: %s",
> + e->symbol_name);
> +
> + print_valid_module_relocs(name);
> + return NULL;
> + }
> + found = e;
> + }
> + }
> + if (found)
> + return found;
> +
> + return NULL;
Since found is either NULL or points to a symbol, the if condition can be
removed and return found directly.
> +}
> +
> +/* Checks if sympos is valid, otherwise prints valid sympos list */
> +static bool valid_sympos(struct sympos *sp)
<snip>
> +
> +/* Returns the right sympos respective to a symbol to be relocated */
> +static bool find_sympos(struct symbol *s, struct sympos *sp)
> +{
> + struct symbol_entry *entry;
> + struct converted_sym *cs;
> +
> + /* did we already convert this symbol? */
> + list_for_each_entry(cs, &converted_symbols, list) {
> + if (cs->symbol == s) {
> + *sp = cs->sympos;
> + return true;
> + }
> + }
> +
> + /* did the user specified via annotation? */
> + if (get_usr_sympos(s, sp)) {
> + if (valid_sympos(sp)) {
> + remember_sympos(s, sp);
> + return true;
> + }
> + return false;
> + }
> +
> + /* search symbol in symbols list */
> + entry = find_sym_entry_by_name(s->name);
> + if (entry) {
> + sp->symbol_name = entry->symbol_name;
> + sp->object_name = entry->object_name;
At this point I believe that it would be good to have a comment about sympos
being 0 means that the symbol wasn't specified by the user, so sympos 0 means
that the symbol is unique.
> + sp->pos = 0;
> + remember_sympos(s, sp);
> + return true;
> + }
> + return false;
> +}
<snip>
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 04/12] livepatch: Add klp-convert annotation helpers
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (2 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 03/12] livepatch: Add klp-convert tool Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 05/12] modpost: Integrate klp-convert Joe Lawrence
` (9 subsequent siblings)
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Josh Poimboeuf <jpoimboe@redhat.com>
Define macros KLP_MODULE_RELOC and KLP_SYMPOS in
include/linux/livepatch.h to improve user-friendliness of the livepatch
annotation process.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
include/linux/livepatch.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 0fb05aae091a..3abb09bd807a 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -237,6 +237,18 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
unsigned int symindex, unsigned int secindex,
const char *objname);
+/* Used to annotate symbol relocations in livepatches */
+#define KLP_MODULE_RELOC(obj) \
+ struct klp_module_reloc \
+ __section(".klp.module_relocs." #obj) \
+ __aligned(4)
+
+#define KLP_SYMPOS(symbol, pos) \
+ { \
+ .sym = &symbol, \
+ .sympos = pos, \
+ }
+
#else /* !CONFIG_LIVEPATCH */
static inline int klp_module_coming(struct module *mod) { return 0; }
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* [RFC PATCH v6 05/12] modpost: Integrate klp-convert
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (3 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 04/12] livepatch: Add klp-convert annotation helpers Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 06/12] livepatch: Add sample livepatch module Joe Lawrence
` (8 subsequent siblings)
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Josh Poimboeuf <jpoimboe@redhat.com>
Create cmd_klp_convert and hook it into scripts/Makefile.modpost.
cmd_klp_convert invokes klp-convert with the right arguments for the
conversion of unresolved symbols inside a livepatch.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
.gitignore | 1 +
Makefile | 18 ++----------------
scripts/Makefile.modfinal | 38 +++++++++++++++++++++++++++++++++++++-
scripts/Makefile.modpost | 5 +++++
scripts/mod/modpost.c | 28 ++++++++++++++++++++++++++--
scripts/mod/modpost.h | 1 +
6 files changed, 72 insertions(+), 19 deletions(-)
diff --git a/.gitignore b/.gitignore
index 50638a15a527..eb0179d00260 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,6 +48,7 @@
*.xz
*.zst
Module.symvers
+modules.livepatch
modules.order
#
diff --git a/Makefile b/Makefile
index 64ec4bc8172c..31d5b6f608d9 100644
--- a/Makefile
+++ b/Makefile
@@ -1089,6 +1089,7 @@ PHONY += prepare0
export extmod_prefix = $(if $(KBUILD_EXTMOD),$(KBUILD_EXTMOD)/)
export MODORDER := $(extmod_prefix)modules.order
export MODULES_NSDEPS := $(extmod_prefix)modules.nsdeps
+export MODULES_LIVEPATCH := $(extmod-prefix)modules.livepatch
ifeq ($(KBUILD_EXTMOD),)
core-y += kernel/ certs/ mm/ fs/ ipc/ security/ crypto/
@@ -1485,7 +1486,7 @@ endif # CONFIG_MODULES
# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
modules.builtin modules.builtin.modinfo modules.nsdeps \
- compile_commands.json .thinlto-cache
+ compile_commands.json .thinlto-cache modules.livepatch
# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated \
@@ -1747,22 +1748,7 @@ PHONY += modules modules_install
ifdef CONFIG_MODULES
-quiet_cmd_klp_map = KLP symbols.klp
-
-define cmd_klp_map
- $(shell echo "klp-convert-symbol-data.0.1" > $(objtree)/symbols.klp) \
- $(shell echo "*vmlinux" >> $(objtree)/symbols.klp) \
- $(shell nm -f posix $(objtree)/vmlinux | cut -d\ -f1 >> $(objtree)/symbols.klp) \
- $(foreach ko, $(sort $(shell cat modules.order)), \
- $(eval mod = $(patsubst %.ko,%.mod,$(ko))) \
- $(eval obj = $(patsubst %.ko,%.o,$(ko))) \
- $(if $(shell grep -o LIVEPATCH $(mod)),, \
- $(shell echo "*$(shell basename -s .ko $(ko))" >> $(objtree)/symbols.klp) \
- $(shell nm -f posix $(obj) | cut -d\ -f1 >> $(objtree)/symbols.klp)))
-endef
-
modules: modules_check
- $(if $(CONFIG_LIVEPATCH), $(call cmd,klp_map))
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
PHONY += modules_check
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 7f39599e9fae..cb31262436ba 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -14,6 +14,8 @@ include $(srctree)/scripts/Makefile.lib
# find all modules listed in modules.order
modules := $(sort $(shell cat $(MODORDER)))
+modules-klp := $(sort $(shell cat $(MODULES_LIVEPATCH)))
+modules-no-klp := $(filter-out $(modules-klp), $(modules))
__modfinal: $(modules)
@:
@@ -56,7 +58,7 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
# Re-generate module BTFs if either module's .ko or vmlinux changed
-$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE
+$(modules-no-klp): %.ko: %$(mod-prelink-ext).o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE
+$(call if_changed_except,ld_ko_o,vmlinux)
ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+$(if $(newer-prereqs),$(call cmd,btf_ko))
@@ -64,6 +66,40 @@ endif
targets += $(modules) $(modules:.ko=.mod.o)
+# Live Patch
+# ---------------------------------------------------------------------------
+
+%.tmp.ko: %.o %.mod.o symbols.klp FORCE
+ +$(call if_changed,ld_ko_o)
+
+quiet_cmd_klp_convert = KLP $@
+ cmd_klp_convert = scripts/livepatch/klp-convert symbols.klp $< $@
+
+$(modules-klp): %.ko: %.tmp.ko FORCE
+ $(call if_changed,klp_convert)
+
+targets += $(modules-klp:.ko=.tmp.ko)
+
+ifeq ($(KBUILD_EXTMOD),)
+# Read out modules.{order,livepatch} instead of expanding $(modules-no-klp).
+# Otherwise, allmodconfig would fail with "Argument list too long".
+filechk_klp_map = \
+ echo "klp-convert-symbol-data.0.1"; \
+ echo "*vmlinux"; \
+ $(NM) -f posix vmlinux | cut -d\ -f1; \
+ sort $(MODORDER) $(MODULES_LIVEPATCH) | \
+ uniq -u | \
+ sed 's/\.ko$$//' | \
+ while read o; \
+ do \
+ echo "*$$(basename $$o)"; \
+ $(NM) -f posix $$o.o | cut -d\ -f1; \
+ done
+
+symbols.klp: FORCE
+ $(call filechk,klp_map)
+endif
+
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 48585c4d04ad..c5df629de7b2 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -48,6 +48,7 @@ MODPOST = scripts/mod/modpost \
$(if $(CONFIG_MODVERSIONS),-m) \
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
+ $(if $(CONFIG_LIVEPATCH),-l $(MODULES_LIVEPATCH)) \
-o $@
ifdef MODPOST_VMLINUX
@@ -136,6 +137,10 @@ $(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(mod-prelink-ext)
targets += $(output-symdump)
__modpost: $(output-symdump)
+ifndef CONFIG_LIVEPATCH
+ $(Q)rm -f $(MODULES_LIVEPATCH)
+ $(Q)touch $(MODULES_LIVEPATCH)
+endif
ifneq ($(KBUILD_MODPOST_NOFINAL),1)
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
endif
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 6bfa33217914..1034b673c95c 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2051,6 +2051,10 @@ static void read_symbols(const char *modname)
handle_moddevtable(mod, &info, sym, symname);
}
+ /* Livepatch modules have unresolved symbols resolved by klp-convert */
+ if (get_modinfo(&info, "livepatch"))
+ mod->livepatch = 1;
+
for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
symname = remove_dot(info.strtab + sym->st_name);
@@ -2170,7 +2174,7 @@ static void check_exports(struct module *mod)
const char *basename;
exp = find_symbol(s->name);
if (!exp || exp->module == mod) {
- if (!s->weak && nr_unresolved++ < MAX_UNRESOLVED_REPORTS)
+ if (!s->weak && !mod->livepatch && nr_unresolved++ < MAX_UNRESOLVED_REPORTS)
modpost_log(warn_unresolved ? LOG_WARN : LOG_ERROR,
"\"%s\" [%s.ko] undefined!\n",
s->name, mod->name);
@@ -2502,6 +2506,20 @@ static void write_namespace_deps_files(const char *fname)
free(ns_deps_buf.p);
}
+static void write_livepatch_modules(const char *fname)
+{
+ struct buffer buf = { };
+ struct module *mod;
+
+ for (mod = modules; mod; mod = mod->next) {
+ if (mod->livepatch)
+ buf_printf(&buf, "%s.ko\n", mod->name);
+ }
+
+ write_if_changed(&buf, fname);
+ free(buf.p);
+}
+
struct dump_list {
struct dump_list *next;
const char *file;
@@ -2513,12 +2531,13 @@ int main(int argc, char **argv)
struct buffer buf = { };
char *missing_namespace_deps = NULL;
char *dump_write = NULL, *files_source = NULL;
+ char *livepatch_modules = NULL;
int opt;
int n;
struct dump_list *dump_read_start = NULL;
struct dump_list **dump_read_iter = &dump_read_start;
- while ((opt = getopt(argc, argv, "ei:mnT:o:awENd:")) != -1) {
+ while ((opt = getopt(argc, argv, "ei:l:mnT:o:awENd:")) != -1) {
switch (opt) {
case 'e':
external_module = 1;
@@ -2529,6 +2548,9 @@ int main(int argc, char **argv)
(*dump_read_iter)->file = optarg;
dump_read_iter = &(*dump_read_iter)->next;
break;
+ case 'l':
+ livepatch_modules = optarg;
+ break;
case 'm':
modversions = 1;
break;
@@ -2605,6 +2627,8 @@ int main(int argc, char **argv)
if (dump_write)
write_dump(dump_write);
+ if (livepatch_modules)
+ write_livepatch_modules(livepatch_modules);
if (sec_mismatch_count && !sec_mismatch_warn_only)
error("Section mismatches detected.\n"
"Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 0c47ff95c0e2..8c7e7e546158 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -123,6 +123,7 @@ struct module {
int seen;
int has_init;
int has_cleanup;
+ int livepatch;
struct buffer dev_table_buf;
char srcversion[25];
// Missing namespace dependencies
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* [RFC PATCH v6 06/12] livepatch: Add sample livepatch module
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (4 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 05/12] modpost: Integrate klp-convert Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2023-02-07 12:52 ` Marcos Paulo de Souza
2022-02-16 16:39 ` [RFC PATCH v6 07/12] documentation: Update on livepatch elf format Joe Lawrence
` (7 subsequent siblings)
13 siblings, 1 reply; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Josh Poimboeuf <jpoimboe@redhat.com>
Add a new livepatch sample in samples/livepatch/ to make use of symbols
that must be post-processed to enable load-time relocation resolution.
As the new sample is to be used as an example, it is annotated with
KLP_MODULE_RELOC and with KLP_SYMPOS macros.
The livepatch sample updates the function cmdline_proc_show to print the
string referenced by the symbol saved_command_line appended by the
string "livepatch=1".
Update livepatch-sample.c to remove livepatch MODULE_INFO statement.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
samples/livepatch/Makefile | 1 +
.../livepatch/livepatch-annotated-sample.c | 93 +++++++++++++++++++
2 files changed, 94 insertions(+)
create mode 100644 samples/livepatch/livepatch-annotated-sample.c
diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile
index 9f853eeb6140..f2b41f4d6c16 100644
--- a/samples/livepatch/Makefile
+++ b/samples/livepatch/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-shadow-fix2.o
obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-demo.o
obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-mod.o
obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-busymod.o
+obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-annotated-sample.o
diff --git a/samples/livepatch/livepatch-annotated-sample.c b/samples/livepatch/livepatch-annotated-sample.c
new file mode 100644
index 000000000000..4fe0e16423c7
--- /dev/null
+++ b/samples/livepatch/livepatch-annotated-sample.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
+ */
+
+/*
+ * livepatch-annotated-sample.c - Kernel Live Patching Sample Module
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+/*
+ * This (dumb) live patch overrides the function that prints the
+ * kernel boot cmdline when /proc/cmdline is read.
+ *
+ * This livepatch uses the symbol saved_command_line whose relocation
+ * must be resolved during load time. To enable that, this module
+ * must be post-processed by a tool called klp-convert, which embeds
+ * information to be used by the loader to solve the relocation.
+ *
+ * The module is annotated with KLP_MODULE_RELOC/KLP_SYMPOS macros.
+ * These annotations are used by klp-convert to infer that the symbol
+ * saved_command_line is in the object vmlinux.
+ *
+ * As saved_command_line has no other homonimous symbol across
+ * kernel objects, this annotation is not a requirement, and can be
+ * suppressed with no harm to klp-convert. Yet, it is kept here as an
+ * example on how to annotate livepatch modules that contain symbols
+ * whose names are used in more than one kernel object.
+ *
+ * Example:
+ *
+ * $ cat /proc/cmdline
+ * <your cmdline>
+ *
+ * $ insmod livepatch-sample.ko
+ * $ cat /proc/cmdline
+ * <your cmdline> livepatch=1
+ *
+ * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
+ * $ cat /proc/cmdline
+ * <your cmdline>
+ */
+
+extern char *saved_command_line;
+
+#include <linux/seq_file.h>
+static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%s livepatch=1\n", saved_command_line);
+ return 0;
+}
+
+KLP_MODULE_RELOC(vmlinux) vmlinux_relocs[] = {
+ KLP_SYMPOS(saved_command_line, 0)
+};
+
+static struct klp_func funcs[] = {
+ {
+ .old_name = "cmdline_proc_show",
+ .new_func = livepatch_cmdline_proc_show,
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ /* name being NULL means vmlinux */
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int livepatch_init(void)
+{
+ return klp_enable_patch(&patch);
+}
+
+static void livepatch_exit(void)
+{
+}
+
+module_init(livepatch_init);
+module_exit(livepatch_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 06/12] livepatch: Add sample livepatch module
2022-02-16 16:39 ` [RFC PATCH v6 06/12] livepatch: Add sample livepatch module Joe Lawrence
@ 2023-02-07 12:52 ` Marcos Paulo de Souza
0 siblings, 0 replies; 28+ messages in thread
From: Marcos Paulo de Souza @ 2023-02-07 12:52 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:34AM -0500, Joe Lawrence wrote:
> From: Josh Poimboeuf <jpoimboe@redhat.com>
>
> Add a new livepatch sample in samples/livepatch/ to make use of symbols
> that must be post-processed to enable load-time relocation resolution.
> As the new sample is to be used as an example, it is annotated with
> KLP_MODULE_RELOC and with KLP_SYMPOS macros.
>
> The livepatch sample updates the function cmdline_proc_show to print the
> string referenced by the symbol saved_command_line appended by the
> string "livepatch=1".
>
> Update livepatch-sample.c to remove livepatch MODULE_INFO statement.
LGTM.
Reviewed-by: Marcos Paulo de Souza <mpdesouza@suse.com>
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> Signed-off-by: Joao Moreira <jmoreira@suse.de>
> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
> ---
> samples/livepatch/Makefile | 1 +
> .../livepatch/livepatch-annotated-sample.c | 93 +++++++++++++++++++
> 2 files changed, 94 insertions(+)
> create mode 100644 samples/livepatch/livepatch-annotated-sample.c
>
> diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile
> index 9f853eeb6140..f2b41f4d6c16 100644
> --- a/samples/livepatch/Makefile
> +++ b/samples/livepatch/Makefile
> @@ -6,3 +6,4 @@ obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-shadow-fix2.o
> obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-demo.o
> obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-mod.o
> obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-callbacks-busymod.o
> +obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-annotated-sample.o
> diff --git a/samples/livepatch/livepatch-annotated-sample.c b/samples/livepatch/livepatch-annotated-sample.c
> new file mode 100644
> index 000000000000..4fe0e16423c7
> --- /dev/null
> +++ b/samples/livepatch/livepatch-annotated-sample.c
> @@ -0,0 +1,93 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
> + */
> +
> +/*
> + * livepatch-annotated-sample.c - Kernel Live Patching Sample Module
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/livepatch.h>
> +
> +/*
> + * This (dumb) live patch overrides the function that prints the
> + * kernel boot cmdline when /proc/cmdline is read.
> + *
> + * This livepatch uses the symbol saved_command_line whose relocation
> + * must be resolved during load time. To enable that, this module
> + * must be post-processed by a tool called klp-convert, which embeds
> + * information to be used by the loader to solve the relocation.
> + *
> + * The module is annotated with KLP_MODULE_RELOC/KLP_SYMPOS macros.
> + * These annotations are used by klp-convert to infer that the symbol
> + * saved_command_line is in the object vmlinux.
> + *
> + * As saved_command_line has no other homonimous symbol across
> + * kernel objects, this annotation is not a requirement, and can be
> + * suppressed with no harm to klp-convert. Yet, it is kept here as an
> + * example on how to annotate livepatch modules that contain symbols
> + * whose names are used in more than one kernel object.
> + *
> + * Example:
> + *
> + * $ cat /proc/cmdline
> + * <your cmdline>
> + *
> + * $ insmod livepatch-sample.ko
> + * $ cat /proc/cmdline
> + * <your cmdline> livepatch=1
> + *
> + * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
> + * $ cat /proc/cmdline
> + * <your cmdline>
> + */
> +
> +extern char *saved_command_line;
> +
> +#include <linux/seq_file.h>
> +static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
> +{
> + seq_printf(m, "%s livepatch=1\n", saved_command_line);
> + return 0;
> +}
> +
> +KLP_MODULE_RELOC(vmlinux) vmlinux_relocs[] = {
> + KLP_SYMPOS(saved_command_line, 0)
> +};
> +
> +static struct klp_func funcs[] = {
> + {
> + .old_name = "cmdline_proc_show",
> + .new_func = livepatch_cmdline_proc_show,
> + }, { }
> +};
> +
> +static struct klp_object objs[] = {
> + {
> + /* name being NULL means vmlinux */
> + .funcs = funcs,
> + }, { }
> +};
> +
> +static struct klp_patch patch = {
> + .mod = THIS_MODULE,
> + .objs = objs,
> +};
> +
> +static int livepatch_init(void)
> +{
> + return klp_enable_patch(&patch);
> +}
> +
> +static void livepatch_exit(void)
> +{
> +}
> +
> +module_init(livepatch_init);
> +module_exit(livepatch_exit);
> +MODULE_LICENSE("GPL");
> +MODULE_INFO(livepatch, "Y");
> --
> 2.26.3
>
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 07/12] documentation: Update on livepatch elf format
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (5 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 06/12] livepatch: Add sample livepatch module Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 08/12] livepatch/selftests: add klp-convert Joe Lawrence
` (6 subsequent siblings)
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
From: Joao Moreira <jmoreira@suse.de>
Add a section to Documentation/livepatch/module-elf-format.rst
describing how klp-convert works for fixing relocations.
Signed-off-by: Joao Moreira <jmoreira@suse.de>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
Documentation/livepatch/livepatch.rst | 3 ++
Documentation/livepatch/module-elf-format.rst | 42 +++++++++++++++++--
2 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/Documentation/livepatch/livepatch.rst b/Documentation/livepatch/livepatch.rst
index 68e3651e8af9..6b317a57c276 100644
--- a/Documentation/livepatch/livepatch.rst
+++ b/Documentation/livepatch/livepatch.rst
@@ -261,6 +261,9 @@ into three levels:
absolute position in the database, but rather the order it has been found
only for a particular object ( vmlinux or a kernel module ). Note that
kallsyms allows for searching symbols according to the object name.
+ Uniquely named symbols may use a symbol position of 0. Non-unique
+ symbols need to specify their object / kallsyms position, starting
+ at position 1.
- struct klp_object defines an array of patched functions (struct
klp_func) in the same object. Where the object is either vmlinux
diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst
index dbe9b400e39f..38cf94dd35c2 100644
--- a/Documentation/livepatch/module-elf-format.rst
+++ b/Documentation/livepatch/module-elf-format.rst
@@ -2,7 +2,8 @@
Livepatch module Elf format
===========================
-This document outlines the Elf format requirements that livepatch modules must follow.
+This document outlines the Elf format requirements that livepatch modules must
+follow.
.. Table of Contents
@@ -259,7 +260,8 @@ Livepatch symbol names must conform to the following format::
The position of the symbol in the object (as according to kallsyms)
This is used to differentiate duplicate symbols within the same
object. The symbol position is expressed numerically (0, 1, 2...).
- The symbol position of a unique symbol is 0.
+ The symbol position of a unique symbol is 0. The symbol position of
+ the first non-unique symbol is 1, the second is 2, etc.
Examples:
---------
@@ -291,7 +293,41 @@ Examples:
Note that the 'Ndx' (Section index) for these symbols is SHN_LIVEPATCH (0xff20).
"OS" means OS-specific.
-5. Symbol table and Elf section access
+5. Automatic conversion of unresolved relocations
+=================================================
+Sometimes livepatches may operate on symbols which are not self-contained nor
+exported. When this happens, these symbols remain unresolved in the elf object
+and will trigger an error during the livepatch instantiation.
+
+Whenever possible, the kernel building infrastructure solves this problem
+automatically. First, a symbol database containing information on all compiled
+objects is built. Second, this database - a file named symbols.klp, placed in
+the kernel source root directory - is used to identify targets for unresolved
+relocations, converting them in the livepatch elf accordingly to the
+specifications above-described. While the first stage is fully handled by the
+building system, the second is done by a tool called klp-convert, which can be
+found in "scripts/livepatch".
+
+When an unresolved relocation has as target a symbol whose name is also used by
+different symbols throughout the kernel, the relocation cannot be resolved
+automatically. In these cases, the livepatch developer must add annotations to
+the livepatch, making it possible for the system to identify which is the
+correct target amongst multiple homonymous symbols. Such annotations must be
+done through a data structure as follows:::
+
+ struct KLP_MODULE_RELOC(object) data_structure_name[] = {
+ KLP_SYMPOS(symbol, pos)
+ };
+
+In the above example, object refers to the object file which contains the
+symbol, being vmlinux or a module; symbol refers to the symbol name that will
+be relocated and pos is its position in the object.
+
+When a data structure like this is added to the livepatch, the resulting elf
+will hold symbols that will be identified by klp-convert and used to solve name
+ambiguities.
+
+6. Symbol table and Elf section access
======================================
A livepatch module's symbol table is accessible through module->symtab.
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* [RFC PATCH v6 08/12] livepatch/selftests: add klp-convert
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (6 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 07/12] documentation: Update on livepatch elf format Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 09/12] livepatch/selftests: test multiple sections Joe Lawrence
` (5 subsequent siblings)
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
Add a simple klp-convert livepatch selftest that exercises various
symbol homonym sympos scenarios.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
lib/livepatch/Makefile | 7 +
lib/livepatch/test_klp_convert.h | 14 ++
lib/livepatch/test_klp_convert1.c | 113 +++++++++++++++
lib/livepatch/test_klp_convert2.c | 110 ++++++++++++++
lib/livepatch/test_klp_convert_mod_a.c | 25 ++++
lib/livepatch/test_klp_convert_mod_b.c | 13 ++
.../selftests/livepatch/test-livepatch.sh | 134 ++++++++++++++++++
7 files changed, 416 insertions(+)
create mode 100644 lib/livepatch/test_klp_convert.h
create mode 100644 lib/livepatch/test_klp_convert1.c
create mode 100644 lib/livepatch/test_klp_convert2.c
create mode 100644 lib/livepatch/test_klp_convert_mod_a.c
create mode 100644 lib/livepatch/test_klp_convert_mod_b.c
diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
index dcc912b3478f..ced00515ff84 100644
--- a/lib/livepatch/Makefile
+++ b/lib/livepatch/Makefile
@@ -7,8 +7,15 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
test_klp_callbacks_demo2.o \
test_klp_callbacks_busy.o \
test_klp_callbacks_mod.o \
+ test_klp_convert1.o \
+ test_klp_convert2.o \
+ test_klp_convert_mod.o \
test_klp_livepatch.o \
test_klp_shadow_vars.o \
test_klp_state.o \
test_klp_state2.o \
test_klp_state3.o
+
+test_klp_convert_mod-y := \
+ test_klp_convert_mod_a.o \
+ test_klp_convert_mod_b.o
diff --git a/lib/livepatch/test_klp_convert.h b/lib/livepatch/test_klp_convert.h
new file mode 100644
index 000000000000..5d97bc546d6e
--- /dev/null
+++ b/lib/livepatch/test_klp_convert.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _TEST_KLP_CONVERT_
+#define _TEST_KLP_CONVERT_
+
+/* klp-convert symbols - vmlinux */
+extern char *saved_command_line;
+/* klp-convert symbols - test_klp_convert_mod.ko */
+extern char driver_name[];
+extern char homonym_string[];
+extern const char *get_homonym_string(void);
+extern const char *test_klp_get_driver_name(void);
+
+#endif
diff --git a/lib/livepatch/test_klp_convert1.c b/lib/livepatch/test_klp_convert1.c
new file mode 100644
index 000000000000..cd2d3c638258
--- /dev/null
+++ b/lib/livepatch/test_klp_convert1.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include "test_klp_convert.h"
+
+void print_saved_command_line(void)
+{
+ pr_info("saved_command_line, 0: %s\n", saved_command_line);
+}
+
+void print_driver_name(void)
+{
+ pr_info("driver_name, 0: %s\n", driver_name);
+ pr_info("test_klp_get_driver_name(), 0: %s\n", test_klp_get_driver_name());
+}
+
+void print_homonym_string(void)
+{
+ pr_info("homonym_string, 1: %s\n", homonym_string);
+ pr_info("get_homonym_string(), 1: %s\n", get_homonym_string());
+}
+
+/* provide a sysfs handle to invoke debug functions */
+static int print_debug;
+static int print_debug_set(const char *val, const struct kernel_param *kp)
+{
+ print_saved_command_line();
+ print_driver_name();
+ print_homonym_string();
+
+ return 0;
+}
+static const struct kernel_param_ops print_debug_ops = {
+ .set = print_debug_set,
+ .get = param_get_int,
+};
+module_param_cb(print_debug, &print_debug_ops, &print_debug, 0200);
+MODULE_PARM_DESC(print_debug, "print klp-convert debugging info");
+
+/*
+ * saved_command_line is a unique symbol, so the sympos annotation is
+ * optional. Provide to test that sympos=0 works correctly.
+ */
+KLP_MODULE_RELOC(vmlinux) vmlinux_relocs[] = {
+ KLP_SYMPOS(saved_command_line, 0)
+};
+
+/*
+ * driver_name symbols can be found in vmlinux (multiple) and also
+ * test_klp_convert_mod, therefore the annotation is required to
+ * clarify that we want the one from test_klp_convert_mod.
+ *
+ * test_klp_convert_mod contains multiple homonym_string and
+ * get_homonym_string symbols, test resolving the first set here and
+ * the others in test_klp_convert2.c
+ *
+ * test_klp_get_driver_name is a uniquely named symbol, test that sympos=0
+ * work correctly.
+ */
+KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
+ KLP_SYMPOS(driver_name, 0),
+ KLP_SYMPOS(homonym_string, 1),
+ KLP_SYMPOS(get_homonym_string, 1),
+ KLP_SYMPOS(test_klp_get_driver_name, 0),
+};
+
+static struct klp_func funcs[] = {
+ {
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ /* name being NULL means vmlinux */
+ .funcs = funcs,
+ },
+ {
+ .name = "test_klp_convert_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int test_klp_convert_init(void)
+{
+ int ret;
+
+ ret = klp_enable_patch(&patch);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void test_klp_convert_exit(void)
+{
+}
+
+module_init(test_klp_convert_init);
+module_exit(test_klp_convert_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert1");
+MODULE_INFO(livepatch, "Y");
diff --git a/lib/livepatch/test_klp_convert2.c b/lib/livepatch/test_klp_convert2.c
new file mode 100644
index 000000000000..93e7b3186018
--- /dev/null
+++ b/lib/livepatch/test_klp_convert2.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include "test_klp_convert.h"
+
+void print_saved_command_line(void)
+{
+ pr_info("saved_command_line (auto): %s\n", saved_command_line);
+}
+
+void print_driver_name(void)
+{
+ pr_info("driver_name, 0: %s\n", driver_name);
+ pr_info("test_klp_get_driver_name(), (auto): %s\n", test_klp_get_driver_name());
+}
+
+void print_homonym_string(void)
+{
+ pr_info("homonym_string, 2: %s\n", homonym_string);
+ pr_info("get_homonym_string(), 2: %s\n", get_homonym_string());
+}
+
+/* provide a sysfs handle to invoke debug functions */
+static int print_debug;
+static int print_debug_set(const char *val, const struct kernel_param *kp)
+{
+ print_saved_command_line();
+ print_driver_name();
+ print_homonym_string();
+
+ return 0;
+}
+static const struct kernel_param_ops print_debug_ops = {
+ .set = print_debug_set,
+ .get = param_get_int,
+};
+module_param_cb(print_debug, &print_debug_ops, &print_debug, 0200);
+MODULE_PARM_DESC(print_debug, "print klp-convert debugging info");
+
+/*
+ * saved_command_line is a uniquely named symbol, so the sympos
+ * annotation is optional. Skip it and test that klp-convert can
+ * resolve the symbol on its own.
+ */
+
+/*
+ * driver_name symbols can be found in vmlinux (multiple) and also
+ * test_klp_convert_mod, therefore the annotation is required to
+ * clarify that we want the one from test_klp_convert_mod.
+ *
+ * test_klp_convert_mod contains multiple homonym_string symbols,
+ * test_klp_convert1.c resolved to the first one, resolve to the
+ * second one here.
+ *
+ * test_klp_get_driver_name is a uniquely named symbol, test klp-convert can
+ * resolve it automatically.
+ */
+KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
+ KLP_SYMPOS(driver_name, 0),
+ KLP_SYMPOS(homonym_string, 2),
+ KLP_SYMPOS(get_homonym_string, 2),
+};
+
+static struct klp_func funcs[] = {
+ {
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ /* name being NULL means vmlinux */
+ .funcs = funcs,
+ },
+ {
+ .name = "test_klp_convert_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int test_klp_convert_init(void)
+{
+ int ret;
+
+ ret = klp_enable_patch(&patch);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void test_klp_convert_exit(void)
+{
+}
+
+module_init(test_klp_convert_init);
+module_exit(test_klp_convert_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert2");
+MODULE_INFO(livepatch, "Y");
diff --git a/lib/livepatch/test_klp_convert_mod_a.c b/lib/livepatch/test_klp_convert_mod_a.c
new file mode 100644
index 000000000000..ae5e911fbb9b
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_mod_a.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+/* Unique symbols that don't need sympos annotation */
+static const char driver_name[] = KBUILD_MODNAME;
+__used static const char *test_klp_get_driver_name(void)
+{
+ return driver_name;
+}
+
+/* Common symbol names that need sympos */
+static const char homonym_string[] = "homonym string A";
+__used static const char *get_homonym_string(void)
+{
+ return homonym_string;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert module");
diff --git a/lib/livepatch/test_klp_convert_mod_b.c b/lib/livepatch/test_klp_convert_mod_b.c
new file mode 100644
index 000000000000..5eca8a4cae38
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_mod_b.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019 Joe Lawrence <joe.lawrence@redhat.com>
+
+/*
+ * A second compilation unit to provide another set of similarly named
+ * symbols, forcing a livepatch to use sympos annotations.
+ */
+
+static const char homonym_string[] = "homonym string B";
+__used static const char *get_homonym_string(void)
+{
+ return homonym_string;
+}
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index 5fe79ac34be1..25c21ddf30f0 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -6,6 +6,10 @@
MOD_LIVEPATCH=test_klp_livepatch
MOD_REPLACE=test_klp_atomic_replace
+MOD_KLP_CONVERT_MOD=test_klp_convert_mod
+MOD_KLP_CONVERT1=test_klp_convert1
+MOD_KLP_CONVERT2=test_klp_convert2
+MOD_KLP_CONVERT_SECTIONS=test_klp_convert_sections
setup_config
@@ -159,4 +163,134 @@ livepatch: '$MOD_REPLACE': unpatching complete
% rmmod $MOD_REPLACE"
+# TEST: klp-convert symbols
+# - load a livepatch that modifies the output from /proc/cmdline
+# including a reference to vmlinux-local symbol that klp-convert
+# will process
+# - verify correct behavior
+# - unload the livepatch and make sure the patch was removed
+
+start_test "klp-convert symbols"
+
+saved_cmdline=$(cat /proc/cmdline)
+
+load_mod $MOD_KLP_CONVERT_MOD
+
+load_lp $MOD_KLP_CONVERT1
+echo 1 > /sys/module/$MOD_KLP_CONVERT1/parameters/print_debug
+disable_lp $MOD_KLP_CONVERT1
+unload_lp $MOD_KLP_CONVERT1
+
+load_lp $MOD_KLP_CONVERT2
+echo 1 > /sys/module/$MOD_KLP_CONVERT2/parameters/print_debug
+disable_lp $MOD_KLP_CONVERT2
+unload_lp $MOD_KLP_CONVERT2
+
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_MOD
+% modprobe $MOD_KLP_CONVERT1
+livepatch: enabling patch '$MOD_KLP_CONVERT1'
+livepatch: '$MOD_KLP_CONVERT1': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT1': starting patching transition
+livepatch: '$MOD_KLP_CONVERT1': completing patching transition
+livepatch: '$MOD_KLP_CONVERT1': patching complete
+$MOD_KLP_CONVERT1: saved_command_line, 0: $saved_cmdline
+$MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
+$MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
+livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': unpatching complete
+% rmmod $MOD_KLP_CONVERT1
+% modprobe $MOD_KLP_CONVERT2
+livepatch: enabling patch '$MOD_KLP_CONVERT2'
+livepatch: '$MOD_KLP_CONVERT2': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT2': starting patching transition
+livepatch: '$MOD_KLP_CONVERT2': completing patching transition
+livepatch: '$MOD_KLP_CONVERT2': patching complete
+$MOD_KLP_CONVERT2: saved_command_line (auto): $saved_cmdline
+$MOD_KLP_CONVERT2: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: test_klp_get_driver_name(), (auto): $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: homonym_string, 2: homonym string B
+$MOD_KLP_CONVERT2: get_homonym_string(), 2: homonym string B
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT2/enabled
+livepatch: '$MOD_KLP_CONVERT2': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': unpatching complete
+% rmmod $MOD_KLP_CONVERT2
+% rmmod $MOD_KLP_CONVERT_MOD"
+
+
+# TEST: klp-convert symbols (late module patching)
+# - load a livepatch that modifies the output from /proc/cmdline
+# including a reference to vmlinux-local symbol that klp-convert
+# will process
+# - load target module
+# - verify correct behavior
+# - unload the livepatch
+
+start_test "klp-convert symbols (late module patching)"
+
+saved_cmdline=$(cat /proc/cmdline)
+
+load_lp $MOD_KLP_CONVERT1
+load_mod $MOD_KLP_CONVERT_MOD
+echo 1 > /sys/module/$MOD_KLP_CONVERT1/parameters/print_debug
+disable_lp $MOD_KLP_CONVERT1
+unload_lp $MOD_KLP_CONVERT1
+unload_mod $MOD_KLP_CONVERT_MOD
+
+load_lp $MOD_KLP_CONVERT2
+load_mod $MOD_KLP_CONVERT_MOD
+echo 1 > /sys/module/$MOD_KLP_CONVERT2/parameters/print_debug
+disable_lp $MOD_KLP_CONVERT2
+unload_lp $MOD_KLP_CONVERT2
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT1
+livepatch: enabling patch '$MOD_KLP_CONVERT1'
+livepatch: '$MOD_KLP_CONVERT1': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT1': starting patching transition
+livepatch: '$MOD_KLP_CONVERT1': completing patching transition
+livepatch: '$MOD_KLP_CONVERT1': patching complete
+% modprobe $MOD_KLP_CONVERT_MOD
+livepatch: applying patch '$MOD_KLP_CONVERT1' to loading module '$MOD_KLP_CONVERT_MOD'
+$MOD_KLP_CONVERT1: saved_command_line, 0: $saved_cmdline
+$MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
+$MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
+livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT1': unpatching complete
+% rmmod $MOD_KLP_CONVERT1
+% rmmod $MOD_KLP_CONVERT_MOD
+% modprobe $MOD_KLP_CONVERT2
+livepatch: enabling patch '$MOD_KLP_CONVERT2'
+livepatch: '$MOD_KLP_CONVERT2': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT2': starting patching transition
+livepatch: '$MOD_KLP_CONVERT2': completing patching transition
+livepatch: '$MOD_KLP_CONVERT2': patching complete
+% modprobe $MOD_KLP_CONVERT_MOD
+livepatch: applying patch '$MOD_KLP_CONVERT2' to loading module '$MOD_KLP_CONVERT_MOD'
+$MOD_KLP_CONVERT2: saved_command_line (auto): $saved_cmdline
+$MOD_KLP_CONVERT2: driver_name, 0: $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: test_klp_get_driver_name(), (auto): $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT2: homonym_string, 2: homonym string B
+$MOD_KLP_CONVERT2: get_homonym_string(), 2: homonym string B
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT2/enabled
+livepatch: '$MOD_KLP_CONVERT2': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT2': unpatching complete
+% rmmod $MOD_KLP_CONVERT2
+% rmmod $MOD_KLP_CONVERT_MOD"
+
exit 0
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* [RFC PATCH v6 09/12] livepatch/selftests: test multiple sections
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (7 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 08/12] livepatch/selftests: add klp-convert Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 10/12] livepatch/selftests: add __asm__ symbol renaming examples Joe Lawrence
` (4 subsequent siblings)
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
Add a test case in which klp-convert needs to convert a symbol that is
shared across ELF sections. Special sections like .altinstructions do
this. It is possible that symbols may be shared across various .text
sections as well.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
lib/livepatch/Makefile | 1 +
lib/livepatch/test_klp_convert_sections.c | 120 ++++++++++++++++++
.../selftests/livepatch/test-livepatch.sh | 43 +++++++
3 files changed, 164 insertions(+)
create mode 100644 lib/livepatch/test_klp_convert_sections.c
diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
index ced00515ff84..77e21317d4da 100644
--- a/lib/livepatch/Makefile
+++ b/lib/livepatch/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
test_klp_callbacks_mod.o \
test_klp_convert1.o \
test_klp_convert2.o \
+ test_klp_convert_sections.o \
test_klp_convert_mod.o \
test_klp_livepatch.o \
test_klp_shadow_vars.o \
diff --git a/lib/livepatch/test_klp_convert_sections.c b/lib/livepatch/test_klp_convert_sections.c
new file mode 100644
index 000000000000..b3f734bf5524
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_sections.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include "test_klp_convert.h"
+
+/* klp-convert symbols - vmlinux */
+extern char *saved_command_line;
+
+/*
+ * Scatter references to the same symbol (saved_command_line) across a
+ * few different ELF sections. At the same time, include multiple
+ * references within the same function.
+ */
+__section(".text.print_saved_command_line")
+void print_saved_command_line(void)
+{
+ pr_info("saved_command_line (1): %s\n", saved_command_line);
+}
+
+__section(".text.print_saved_command_line2")
+void print_saved_command_line2(void)
+{
+ pr_info("saved_command_line (1): %s\n", saved_command_line);
+ pr_info("saved_command_line (2): %s\n", saved_command_line);
+}
+
+__section(".text.print_saved_command_line3")
+void print_saved_command_line3(void)
+{
+ pr_info("saved_command_line (1): %s\n", saved_command_line);
+ pr_info("saved_command_line (2): %s\n", saved_command_line);
+ pr_info("saved_command_line (3): %s\n", saved_command_line);
+}
+
+/*
+ * Create relocations in .rela.data that need conversion, sharing
+ * symbols with ordinary .text relas.
+ */
+const char *(*p_test_klp_get_driver_name)(void) = test_klp_get_driver_name;
+const char *(*p_get_homonym_string)(void) = get_homonym_string;
+
+void print_via_function_pointers(void)
+{
+ pr_info("test_klp_get_driver_name(): %s\n", test_klp_get_driver_name());
+ pr_info("p_test_klp_get_driver_name(): %s\n", p_test_klp_get_driver_name());
+ pr_info("get_homonym_string(): %s\n", get_homonym_string());
+ pr_info("p_get_homonym_string(): %s\n", p_get_homonym_string());
+}
+
+/* provide a sysfs handle to invoke debug functions */
+static int print_debug;
+static int print_debug_set(const char *val, const struct kernel_param *kp)
+{
+ print_saved_command_line();
+ print_saved_command_line2();
+ print_saved_command_line3();
+ print_via_function_pointers();
+
+ return 0;
+}
+static const struct kernel_param_ops print_debug_ops = {
+ .set = print_debug_set,
+ .get = param_get_int,
+};
+
+module_param_cb(print_debug, &print_debug_ops, &print_debug, 0200);
+MODULE_PARM_DESC(print_debug, "print klp-convert debugging info");
+
+
+KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
+ KLP_SYMPOS(get_homonym_string, 1),
+};
+
+static struct klp_func funcs[] = {
+ {
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ /* name being NULL means vmlinux */
+ .funcs = funcs,
+ },
+ {
+ .name = "test_klp_convert_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int test_klp_convert_sections_init(void)
+{
+ int ret;
+
+ ret = klp_enable_patch(&patch);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void test_klp_convert_sections_exit(void)
+{
+}
+
+module_init(test_klp_convert_sections_init);
+module_exit(test_klp_convert_sections_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert-sections");
+MODULE_INFO(livepatch, "Y");
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index 25c21ddf30f0..bcb8b468b80a 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -293,4 +293,47 @@ livepatch: '$MOD_KLP_CONVERT2': unpatching complete
% rmmod $MOD_KLP_CONVERT2
% rmmod $MOD_KLP_CONVERT_MOD"
+
+# TEST: klp-convert symbols across ELF sections
+# - load a livepatch that references symbols that require klp-convert
+# and reference the same symbol from multiple ELF sections
+# - verify correct behavior
+# - unload the livepatch
+
+start_test "klp-convert symbols across ELF sections"
+
+saved_cmdline=$(cat /proc/cmdline)
+
+load_mod $MOD_KLP_CONVERT_MOD
+load_lp $MOD_KLP_CONVERT_SECTIONS
+echo 1 > /sys/module/$MOD_KLP_CONVERT_SECTIONS/parameters/print_debug
+disable_lp $MOD_KLP_CONVERT_SECTIONS
+unload_lp $MOD_KLP_CONVERT_SECTIONS
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_MOD
+% modprobe $MOD_KLP_CONVERT_SECTIONS
+livepatch: enabling patch '$MOD_KLP_CONVERT_SECTIONS'
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': starting patching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': completing patching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': patching complete
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (1): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (1): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (2): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (1): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (2): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: saved_command_line (3): $saved_cmdline
+$MOD_KLP_CONVERT_SECTIONS: test_klp_get_driver_name(): $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT_SECTIONS: p_test_klp_get_driver_name(): $MOD_KLP_CONVERT_MOD
+$MOD_KLP_CONVERT_SECTIONS: get_homonym_string(): homonym string A
+$MOD_KLP_CONVERT_SECTIONS: p_get_homonym_string(): homonym string A
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT_SECTIONS/enabled
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_SECTIONS': unpatching complete
+% rmmod $MOD_KLP_CONVERT_SECTIONS
+% rmmod $MOD_KLP_CONVERT_MOD"
+
exit 0
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* [RFC PATCH v6 10/12] livepatch/selftests: add __asm__ symbol renaming examples
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (8 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 09/12] livepatch/selftests: test multiple sections Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 17:03 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 11/12] livepatch/selftests: add data relocations test Joe Lawrence
` (3 subsequent siblings)
13 siblings, 1 reply; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
GCC can rename symbols like static data and optimized functions, adding
a suffix that includes illegal C characters. Extend the klp-convert
examples to demonstrate how to use __asm__ renaming from C code to
create klp-relocations to such renamed symbols.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
lib/livepatch/test_klp_convert.h | 2 ++
lib/livepatch/test_klp_convert1.c | 8 ++++++++
lib/livepatch/test_klp_convert_mod_a.c | 6 ++++++
lib/livepatch/test_klp_convert_mod_b.c | 6 ++++++
tools/testing/selftests/livepatch/test-livepatch.sh | 4 ++++
5 files changed, 26 insertions(+)
diff --git a/lib/livepatch/test_klp_convert.h b/lib/livepatch/test_klp_convert.h
index 5d97bc546d6e..42befbfd63cb 100644
--- a/lib/livepatch/test_klp_convert.h
+++ b/lib/livepatch/test_klp_convert.h
@@ -10,5 +10,7 @@ extern char driver_name[];
extern char homonym_string[];
extern const char *get_homonym_string(void);
extern const char *test_klp_get_driver_name(void);
+extern char klp_string_a[] __asm__("klp_string.12345");
+extern char klp_string_b[] __asm__("klp_string.67890");
#endif
diff --git a/lib/livepatch/test_klp_convert1.c b/lib/livepatch/test_klp_convert1.c
index cd2d3c638258..06926cf1c609 100644
--- a/lib/livepatch/test_klp_convert1.c
+++ b/lib/livepatch/test_klp_convert1.c
@@ -25,6 +25,12 @@ void print_homonym_string(void)
pr_info("get_homonym_string(), 1: %s\n", get_homonym_string());
}
+void print_static_strings(void)
+{
+ pr_info("klp_string.12345 = %s\n", klp_string_a);
+ pr_info("klp_string.67890 = %s\n", klp_string_b);
+}
+
/* provide a sysfs handle to invoke debug functions */
static int print_debug;
static int print_debug_set(const char *val, const struct kernel_param *kp)
@@ -32,6 +38,7 @@ static int print_debug_set(const char *val, const struct kernel_param *kp)
print_saved_command_line();
print_driver_name();
print_homonym_string();
+ print_static_strings();
return 0;
}
@@ -67,6 +74,7 @@ KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
KLP_SYMPOS(homonym_string, 1),
KLP_SYMPOS(get_homonym_string, 1),
KLP_SYMPOS(test_klp_get_driver_name, 0),
+ KLP_SYMPOS(klp_string_b, 1),
};
static struct klp_func funcs[] = {
diff --git a/lib/livepatch/test_klp_convert_mod_a.c b/lib/livepatch/test_klp_convert_mod_a.c
index ae5e911fbb9b..9af0fcab0c8d 100644
--- a/lib/livepatch/test_klp_convert_mod_a.c
+++ b/lib/livepatch/test_klp_convert_mod_a.c
@@ -20,6 +20,12 @@ __used static const char *get_homonym_string(void)
return homonym_string;
}
+__used static void static_string_function(void)
+{
+ __used static char klp_string[] __asm__("klp_string.12345") =
+ __FILE__ " static string";
+}
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
MODULE_DESCRIPTION("Livepatch test: klp-convert module");
diff --git a/lib/livepatch/test_klp_convert_mod_b.c b/lib/livepatch/test_klp_convert_mod_b.c
index 5eca8a4cae38..0a68e898fe03 100644
--- a/lib/livepatch/test_klp_convert_mod_b.c
+++ b/lib/livepatch/test_klp_convert_mod_b.c
@@ -11,3 +11,9 @@ __used static const char *get_homonym_string(void)
{
return homonym_string;
}
+
+__used static void static_string_function(void)
+{
+ __used static char klp_string[] __asm__("klp_string.67890") =
+ __FILE__ " static string";
+}
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index bcb8b468b80a..ec3b6c919b01 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -200,6 +200,8 @@ $MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
$MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
$MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
$MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
+test_klp_convert1: klp_string.12345 = lib/livepatch/test_klp_convert_mod_a.c static string
+test_klp_convert1: klp_string.67890 = lib/livepatch/test_klp_convert_mod_b.c static string
% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
@@ -265,6 +267,8 @@ $MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
$MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
$MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
$MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
+test_klp_convert1: klp_string.12345 = lib/livepatch/test_klp_convert_mod_a.c static string
+test_klp_convert1: klp_string.67890 = lib/livepatch/test_klp_convert_mod_b.c static string
% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 10/12] livepatch/selftests: add __asm__ symbol renaming examples
2022-02-16 16:39 ` [RFC PATCH v6 10/12] livepatch/selftests: add __asm__ symbol renaming examples Joe Lawrence
@ 2022-02-16 17:03 ` Joe Lawrence
0 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 17:03 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:38AM -0500, Joe Lawrence wrote:
> GCC can rename symbols like static data and optimized functions, adding
> a suffix that includes illegal C characters. Extend the klp-convert
> examples to demonstrate how to use __asm__ renaming from C code to
> create klp-relocations to such renamed symbols.
>
> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
> ---
> lib/livepatch/test_klp_convert.h | 2 ++
> lib/livepatch/test_klp_convert1.c | 8 ++++++++
> lib/livepatch/test_klp_convert_mod_a.c | 6 ++++++
> lib/livepatch/test_klp_convert_mod_b.c | 6 ++++++
> tools/testing/selftests/livepatch/test-livepatch.sh | 4 ++++
> 5 files changed, 26 insertions(+)
>
> diff --git a/lib/livepatch/test_klp_convert.h b/lib/livepatch/test_klp_convert.h
> index 5d97bc546d6e..42befbfd63cb 100644
> --- a/lib/livepatch/test_klp_convert.h
> +++ b/lib/livepatch/test_klp_convert.h
> @@ -10,5 +10,7 @@ extern char driver_name[];
> extern char homonym_string[];
> extern const char *get_homonym_string(void);
> extern const char *test_klp_get_driver_name(void);
> +extern char klp_string_a[] __asm__("klp_string.12345");
> +extern char klp_string_b[] __asm__("klp_string.67890");
>
> #endif
> diff --git a/lib/livepatch/test_klp_convert1.c b/lib/livepatch/test_klp_convert1.c
> index cd2d3c638258..06926cf1c609 100644
> --- a/lib/livepatch/test_klp_convert1.c
> +++ b/lib/livepatch/test_klp_convert1.c
> @@ -25,6 +25,12 @@ void print_homonym_string(void)
> pr_info("get_homonym_string(), 1: %s\n", get_homonym_string());
> }
>
> +void print_static_strings(void)
> +{
> + pr_info("klp_string.12345 = %s\n", klp_string_a);
> + pr_info("klp_string.67890 = %s\n", klp_string_b);
> +}
> +
> /* provide a sysfs handle to invoke debug functions */
> static int print_debug;
> static int print_debug_set(const char *val, const struct kernel_param *kp)
> @@ -32,6 +38,7 @@ static int print_debug_set(const char *val, const struct kernel_param *kp)
> print_saved_command_line();
> print_driver_name();
> print_homonym_string();
> + print_static_strings();
>
> return 0;
> }
> @@ -67,6 +74,7 @@ KLP_MODULE_RELOC(test_klp_convert_mod) test_klp_convert_mod_relocs_a[] = {
> KLP_SYMPOS(homonym_string, 1),
> KLP_SYMPOS(get_homonym_string, 1),
> KLP_SYMPOS(test_klp_get_driver_name, 0),
> + KLP_SYMPOS(klp_string_b, 1),
> };
>
> static struct klp_func funcs[] = {
> diff --git a/lib/livepatch/test_klp_convert_mod_a.c b/lib/livepatch/test_klp_convert_mod_a.c
> index ae5e911fbb9b..9af0fcab0c8d 100644
> --- a/lib/livepatch/test_klp_convert_mod_a.c
> +++ b/lib/livepatch/test_klp_convert_mod_a.c
> @@ -20,6 +20,12 @@ __used static const char *get_homonym_string(void)
> return homonym_string;
> }
>
> +__used static void static_string_function(void)
> +{
> + __used static char klp_string[] __asm__("klp_string.12345") =
> + __FILE__ " static string";
> +}
> +
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
> MODULE_DESCRIPTION("Livepatch test: klp-convert module");
> diff --git a/lib/livepatch/test_klp_convert_mod_b.c b/lib/livepatch/test_klp_convert_mod_b.c
> index 5eca8a4cae38..0a68e898fe03 100644
> --- a/lib/livepatch/test_klp_convert_mod_b.c
> +++ b/lib/livepatch/test_klp_convert_mod_b.c
> @@ -11,3 +11,9 @@ __used static const char *get_homonym_string(void)
> {
> return homonym_string;
> }
> +
> +__used static void static_string_function(void)
> +{
> + __used static char klp_string[] __asm__("klp_string.67890") =
> + __FILE__ " static string";
> +}
> diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
> index bcb8b468b80a..ec3b6c919b01 100755
> --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> @@ -200,6 +200,8 @@ $MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
> $MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
> $MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
> $MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
> +test_klp_convert1: klp_string.12345 = lib/livepatch/test_klp_convert_mod_a.c static string
> +test_klp_convert1: klp_string.67890 = lib/livepatch/test_klp_convert_mod_b.c static string
> % echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
> livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
> livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
> @@ -265,6 +267,8 @@ $MOD_KLP_CONVERT1: driver_name, 0: $MOD_KLP_CONVERT_MOD
> $MOD_KLP_CONVERT1: test_klp_get_driver_name(), 0: $MOD_KLP_CONVERT_MOD
> $MOD_KLP_CONVERT1: homonym_string, 1: homonym string A
> $MOD_KLP_CONVERT1: get_homonym_string(), 1: homonym string A
> +test_klp_convert1: klp_string.12345 = lib/livepatch/test_klp_convert_mod_a.c static string
> +test_klp_convert1: klp_string.67890 = lib/livepatch/test_klp_convert_mod_b.c static string
> % echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT1/enabled
> livepatch: '$MOD_KLP_CONVERT1': initializing unpatching transition
> livepatch: '$MOD_KLP_CONVERT1': starting unpatching transition
> --
> 2.26.3
>
I'm not sure how portable it is using __asm__("new.name"), but it seems
to work with versions of GCC that I've tried. Other tools like
kpatch-build can manipulate such symbols directly, but for anything that
needs to feed the C compiler, some kind of workaround is needed to
create klp-relocations for them.
FWIW, the trick works through the KLP_SYMPOS macro annotations as well,
for example:
void pfn_valid_part_0(void) __asm__("pfn_valid.part.0");
KLP_MODULE_RELOC(kvm) kvm_main_relocs[] = {
KLP_SYMPOS(pfn_valid_part_0, 0),
};
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 11/12] livepatch/selftests: add data relocations test
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (9 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 10/12] livepatch/selftests: add __asm__ symbol renaming examples Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 17:12 ` Joe Lawrence
2022-02-16 16:39 ` [RFC PATCH v6 12/12] livepatch/selftests: add static keys test Joe Lawrence
` (2 subsequent siblings)
13 siblings, 1 reply; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
Add a test which creates a variety of klp-data-relocations. Note that
this test case exercises late-klp-relocations for references to data.
For this, we only need to adjust pointer storage classes (and not the
target data) to affect where the relocation ends up.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
lib/livepatch/Makefile | 4 +-
lib/livepatch/test_klp_convert.h | 21 ++
lib/livepatch/test_klp_convert_data.c | 190 ++++++++++++++++++
lib/livepatch/test_klp_convert_mod_c.c | 36 ++++
.../selftests/livepatch/test-livepatch.sh | 97 +++++++++
5 files changed, 347 insertions(+), 1 deletion(-)
create mode 100644 lib/livepatch/test_klp_convert_data.c
create mode 100644 lib/livepatch/test_klp_convert_mod_c.c
diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
index 77e21317d4da..da39aaa5c8fc 100644
--- a/lib/livepatch/Makefile
+++ b/lib/livepatch/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
test_klp_callbacks_mod.o \
test_klp_convert1.o \
test_klp_convert2.o \
+ test_klp_convert_data.o \
test_klp_convert_sections.o \
test_klp_convert_mod.o \
test_klp_livepatch.o \
@@ -19,4 +20,5 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
test_klp_convert_mod-y := \
test_klp_convert_mod_a.o \
- test_klp_convert_mod_b.o
+ test_klp_convert_mod_b.o \
+ test_klp_convert_mod_c.o
diff --git a/lib/livepatch/test_klp_convert.h b/lib/livepatch/test_klp_convert.h
index 42befbfd63cb..08c0f4b1dc6b 100644
--- a/lib/livepatch/test_klp_convert.h
+++ b/lib/livepatch/test_klp_convert.h
@@ -12,5 +12,26 @@ extern const char *get_homonym_string(void);
extern const char *test_klp_get_driver_name(void);
extern char klp_string_a[] __asm__("klp_string.12345");
extern char klp_string_b[] __asm__("klp_string.67890");
+extern int global_small;
+// .rela.data.rel.ro, .rela.rodata supported ???:
+extern int const_global_small;
+extern int static_small;
+extern int static_const_small;
+extern int global_large[];
+// .rela.data.rel.ro, .rela.rodata supported ???:
+extern int const_global_large[];
+extern int static_large[];
+extern int static_const_large[];
+extern int local_small;
+extern int const_local_small;
+extern int static_local_small;
+extern int static_const_local_small;
+extern int local_large[4];
+extern int const_local_large[4];
+extern int static_local_large[4];
+extern int static_const_local_large[4];
+// .rela.data..ro_after_init supported ???:
+extern int static_ro_after_init;
+extern int static_read_mostly;
#endif
diff --git a/lib/livepatch/test_klp_convert_data.c b/lib/livepatch/test_klp_convert_data.c
new file mode 100644
index 000000000000..142422664159
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_data.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2021 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/cache.h>
+#include <linux/livepatch.h>
+#include "test_klp_convert.h"
+
+/* Small global */
+int *p_global_small = &global_small;
+
+/* Small global (const) */
+// .rela.data.rel.ro, .rela.rodata supported ???:
+int * const p_const_global_small = &const_global_small;
+
+/* Small file-static */
+static int *p_static_small = &static_small;
+
+/* Small file-static (constant) */
+static int * const p_static_const_small = &static_const_small;
+
+/* Large global */
+int *p_global_large[4] = {
+ &global_large[0], &global_large[1],
+ &global_large[2], &global_large[3],
+};
+
+/* Large global (const) */
+// .rela.data.rel.ro, .rela.rodata supported ???:
+int * const p_const_global_large[4] = {
+ &const_global_large[0], &const_global_large[1],
+ &const_global_large[2], &const_global_large[3],
+};
+
+/* Large file-static global */
+static int *p_static_large[4] = {
+ &static_large[0], &static_large[1],
+ &static_large[2], &static_large[3],
+};
+
+/* Large file-static (const) */
+static int * const p_static_const_large[4] = {
+ &static_const_large[0], &static_const_large[1],
+ &static_const_large[2], &static_const_large[3],
+};
+
+// .rela.data.rel.ro, .rela.rodata supported ???:
+static int * __ro_after_init p_static_ro_after_init = &static_ro_after_init;
+static int * __read_mostly p_static_read_mostly = &static_read_mostly;
+
+static void print_variables(void)
+{
+ /* Small local */
+ int *p_local_small = &local_small;
+
+ /* Small local (const) */
+ int * const p_const_local_small = &const_local_small;
+
+ /* Small static-local */
+ static int *p_static_local_small = &static_local_small;
+
+ /* Small static-local (const) */
+ static int * const p_static_const_local_small = &static_const_local_small;
+
+ /* Large local */
+ int *p_local_large[4] = {
+ &local_large[0], &local_large[1],
+ &local_large[2], &local_large[3],
+ };
+
+ /* Large local (const) */
+ int * const p_const_local_large[4] = {
+ &const_local_large[0], &const_local_large[1],
+ &const_local_large[2], &const_local_large[3],
+ };
+
+ /* Large static-local local */
+ static int *p_static_local_large[4] = {
+ &static_local_large[0], &static_local_large[1],
+ &static_local_large[2], &static_local_large[3],
+ };
+
+ /* Large static-local (const) */
+ static int * const p_static_const_local_large[4] = {
+ &static_const_local_large[0], &static_const_local_large[1],
+ &static_const_local_large[2], &static_const_local_large[3],
+ };
+
+ pr_info("local_small: %x\n", *p_local_small);
+ pr_info("const_local_small: %x\n", *p_const_local_small);
+ pr_info("static_local_small: %x\n", *p_static_local_small);
+ pr_info("static_const_local_small: %x\n", *p_static_const_local_small);
+ pr_info("local_large[0..3]: %x %x %x %x\n",
+ *p_local_large[0], *p_local_large[1],
+ *p_local_large[2], *p_local_large[3]);
+ pr_info("const_local_large[0..3]: %x %x %x %x\n",
+ *p_const_local_large[0], *p_const_local_large[1],
+ *p_const_local_large[2], *p_const_local_large[3]);
+ pr_info("static_local_large[0..3]: %x %x %x %x\n",
+ *p_static_local_large[0], *p_static_local_large[1],
+ *p_static_local_large[2], *p_static_local_large[3]);
+ pr_info("static_const_local_large[0..3]: %x %x %x %x\n",
+ *p_static_const_local_large[0], *p_static_const_local_large[1],
+ *p_static_const_local_large[2], *p_static_const_local_large[3]);
+
+ pr_info("global_small: %x\n", *p_global_small);
+ // .rela.data.rel.ro, .rela.rodata supported ???:
+ pr_info("const_global_small: %x\n", *p_const_global_small);
+ pr_info("static_small: %x\n", *p_static_small);
+ pr_info("static_const_small: %x\n", *p_static_const_small);
+ pr_info("global_large[0..3]: %x %x %x %x\n",
+ *p_global_large[0], *p_global_large[1],
+ *p_global_large[2], *p_global_large[3]);
+ // .rela.data.rel.ro, .rela.rodata supported ???:
+ pr_info("const_global_large[0..3]: %x %x %x %x\n",
+ *p_const_global_large[0], *p_const_global_large[1],
+ *p_const_global_large[2], *p_const_global_large[3]);
+ pr_info("static_large[0..3]: %x %x %x %x\n",
+ *p_static_large[0], *p_static_large[1],
+ *p_static_large[2], *p_static_large[3]);
+ pr_info("static_const_large[0..3]: %x %x %x %x\n",
+ *p_static_const_large[0], *p_static_const_large[1],
+ *p_static_const_large[2], *p_static_const_large[3]);
+
+ // .rela.data..ro_after_init supported ???:
+ pr_info("static_ro_after_init: %x\n", *p_static_ro_after_init);
+ pr_info("static_read_mostly: %x\n", *p_static_read_mostly);
+}
+
+/* provide a sysfs handle to invoke debug functions */
+static int print_debug;
+static int print_debug_set(const char *val, const struct kernel_param *kp)
+{
+ print_variables();
+
+ return 0;
+}
+static const struct kernel_param_ops print_debug_ops = {
+ .set = print_debug_set,
+ .get = param_get_int,
+};
+module_param_cb(print_debug, &print_debug_ops, &print_debug, 0200);
+MODULE_PARM_DESC(print_debug, "print klp-convert debugging info");
+
+
+static struct klp_func funcs[] = {
+ {
+ }, { }
+};
+
+static struct klp_object objs[] = {
+ {
+ /* name being NULL means vmlinux */
+ .funcs = funcs,
+ },
+ {
+ .name = "test_klp_convert_mod",
+ .funcs = funcs,
+ }, { }
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int test_klp_convert_init(void)
+{
+ int ret;
+
+ ret = klp_enable_patch(&patch);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void test_klp_convert_exit(void)
+{
+}
+
+module_init(test_klp_convert_init);
+module_exit(test_klp_convert_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: klp-convert-data");
+MODULE_INFO(livepatch, "Y");
diff --git a/lib/livepatch/test_klp_convert_mod_c.c b/lib/livepatch/test_klp_convert_mod_c.c
new file mode 100644
index 000000000000..2bf11d486548
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_mod_c.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2021 Joe Lawrence <joe.lawrence@redhat.com>
+
+#include <linux/types.h>
+
+/*
+ * test_klp_convert_data will create klp-relocations to these variables.
+ * They are named for the storage class of the variable that refers to
+ * the. This makes it easier to correlate those symbols to the
+ * relocations that refer to them in readelf output.
+ */
+__used static int global_small = 0x1111;
+// .rela.data.rel.ro, .rela.rodata supported ???:
+__used static int const_global_small = 0x2222;
+__used static int static_small = 0x3333;
+__used static int static_const_small = 0x4444;
+
+__used static int global_large[4] = { 0x1111, 0x2222, 0x3333, 0x4444 };
+// .rela.data.rel.ro, .rela.rodata supported ???:
+__used static int const_global_large[4] = { 0x5555, 0x6666, 0x7777, 0x8888 };
+__used static int static_large[4] = { 0x9999, 0xaaaa, 0xbbbb, 0xcccc };
+__used static int static_const_large[4] = { 0xdddd, 0xeeee, 0xffff, 0x0000 };
+
+__used static int local_small = 0x1111;
+__used static int const_local_small = 0x2222;
+__used static int static_local_small = 0x3333;
+__used static int static_const_local_small = 0x4444;
+
+__used static int local_large[4] = { 0x1111, 0x2222, 0x3333, 0x4444 };
+__used static int const_local_large[4] = { 0x5555, 0x6666, 0x7777, 0x8888 };
+__used static int static_local_large[4] = { 0x9999, 0xaaaa, 0xbbbb, 0xcccc };
+__used static int static_const_local_large[4] = { 0xdddd, 0xeeee, 0xffff, 0x0000 };
+
+// .rela.data..ro_after_init supported ???:
+__used static int static_ro_after_init = 0x1111;
+__used static int static_read_mostly = 0x2222;
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index ec3b6c919b01..e3e2f59152e1 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -9,6 +9,7 @@ MOD_REPLACE=test_klp_atomic_replace
MOD_KLP_CONVERT_MOD=test_klp_convert_mod
MOD_KLP_CONVERT1=test_klp_convert1
MOD_KLP_CONVERT2=test_klp_convert2
+MOD_KLP_CONVERT_DATA=test_klp_convert_data
MOD_KLP_CONVERT_SECTIONS=test_klp_convert_sections
setup_config
@@ -340,4 +341,100 @@ livepatch: '$MOD_KLP_CONVERT_SECTIONS': unpatching complete
% rmmod $MOD_KLP_CONVERT_SECTIONS
% rmmod $MOD_KLP_CONVERT_MOD"
+
+# TEST: klp-convert data relocations
+
+start_test "klp-convert data relocations"
+
+load_mod $MOD_KLP_CONVERT_MOD
+load_lp $MOD_KLP_CONVERT_DATA
+
+echo 1 > /sys/module/$MOD_KLP_CONVERT_DATA/parameters/print_debug
+
+disable_lp $MOD_KLP_CONVERT_DATA
+unload_lp $MOD_KLP_CONVERT_DATA
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_MOD
+% modprobe $MOD_KLP_CONVERT_DATA
+livepatch: enabling patch '$MOD_KLP_CONVERT_DATA'
+livepatch: '$MOD_KLP_CONVERT_DATA': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': starting patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': completing patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': patching complete
+$MOD_KLP_CONVERT_DATA: local_small: 1111
+$MOD_KLP_CONVERT_DATA: const_local_small: 2222
+$MOD_KLP_CONVERT_DATA: static_local_small: 3333
+$MOD_KLP_CONVERT_DATA: static_const_local_small: 4444
+$MOD_KLP_CONVERT_DATA: local_large[0..3]: 1111 2222 3333 4444
+$MOD_KLP_CONVERT_DATA: const_local_large[0..3]: 5555 6666 7777 8888
+$MOD_KLP_CONVERT_DATA: static_local_large[0..3]: 9999 aaaa bbbb cccc
+$MOD_KLP_CONVERT_DATA: static_const_local_large[0..3]: dddd eeee ffff 0
+$MOD_KLP_CONVERT_DATA: global_small: 1111
+$MOD_KLP_CONVERT_DATA: const_global_small: 2222
+$MOD_KLP_CONVERT_DATA: static_small: 3333
+$MOD_KLP_CONVERT_DATA: static_const_small: 4444
+$MOD_KLP_CONVERT_DATA: global_large[0..3]: 1111 2222 3333 4444
+$MOD_KLP_CONVERT_DATA: const_global_large[0..3]: 5555 6666 7777 8888
+$MOD_KLP_CONVERT_DATA: static_large[0..3]: 9999 aaaa bbbb cccc
+$MOD_KLP_CONVERT_DATA: static_const_large[0..3]: dddd eeee ffff 0
+$MOD_KLP_CONVERT_DATA: static_ro_after_init: 1111
+$MOD_KLP_CONVERT_DATA: static_read_mostly: 2222
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT_DATA/enabled
+livepatch: '$MOD_KLP_CONVERT_DATA': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': unpatching complete
+% rmmod $MOD_KLP_CONVERT_DATA
+% rmmod $MOD_KLP_CONVERT_MOD"
+
+
+# TEST: klp-convert data relocations (late module patching)
+
+start_test "klp-convert data relocations (late module patching)"
+
+load_lp $MOD_KLP_CONVERT_DATA
+load_mod $MOD_KLP_CONVERT_MOD
+
+echo 1 > /sys/module/$MOD_KLP_CONVERT_DATA/parameters/print_debug
+
+disable_lp $MOD_KLP_CONVERT_DATA
+unload_lp $MOD_KLP_CONVERT_DATA
+unload_mod $MOD_KLP_CONVERT_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_DATA
+livepatch: enabling patch '$MOD_KLP_CONVERT_DATA'
+livepatch: '$MOD_KLP_CONVERT_DATA': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': starting patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': completing patching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': patching complete
+% modprobe $MOD_KLP_CONVERT_MOD
+livepatch: applying patch '$MOD_KLP_CONVERT_DATA' to loading module '$MOD_KLP_CONVERT_MOD'
+$MOD_KLP_CONVERT_DATA: local_small: 1111
+$MOD_KLP_CONVERT_DATA: const_local_small: 2222
+$MOD_KLP_CONVERT_DATA: static_local_small: 3333
+$MOD_KLP_CONVERT_DATA: static_const_local_small: 4444
+$MOD_KLP_CONVERT_DATA: local_large[0..3]: 1111 2222 3333 4444
+$MOD_KLP_CONVERT_DATA: const_local_large[0..3]: 5555 6666 7777 8888
+$MOD_KLP_CONVERT_DATA: static_local_large[0..3]: 9999 aaaa bbbb cccc
+$MOD_KLP_CONVERT_DATA: static_const_local_large[0..3]: dddd eeee ffff 0
+$MOD_KLP_CONVERT_DATA: global_small: 1111
+$MOD_KLP_CONVERT_DATA: const_global_small: 2222
+$MOD_KLP_CONVERT_DATA: static_small: 3333
+$MOD_KLP_CONVERT_DATA: static_const_small: 4444
+$MOD_KLP_CONVERT_DATA: global_large[0..3]: 1111 2222 3333 4444
+$MOD_KLP_CONVERT_DATA: const_global_large[0..3]: 5555 6666 7777 8888
+$MOD_KLP_CONVERT_DATA: static_large[0..3]: 9999 aaaa bbbb cccc
+$MOD_KLP_CONVERT_DATA: static_const_large[0..3]: dddd eeee ffff 0
+$MOD_KLP_CONVERT_DATA: static_ro_after_init: 1111
+$MOD_KLP_CONVERT_DATA: static_read_mostly: 2222
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT_DATA/enabled
+livepatch: '$MOD_KLP_CONVERT_DATA': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_DATA': unpatching complete
+% rmmod $MOD_KLP_CONVERT_DATA
+% rmmod $MOD_KLP_CONVERT_MOD"
+
+
exit 0
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 11/12] livepatch/selftests: add data relocations test
2022-02-16 16:39 ` [RFC PATCH v6 11/12] livepatch/selftests: add data relocations test Joe Lawrence
@ 2022-02-16 17:12 ` Joe Lawrence
0 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 17:12 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:39AM -0500, Joe Lawrence wrote:
>
> [ ... snip ... ]
>
> diff --git a/lib/livepatch/test_klp_convert_data.c b/lib/livepatch/test_klp_convert_data.c
> new file mode 100644
> index 000000000000..142422664159
> --- /dev/null
> +++ b/lib/livepatch/test_klp_convert_data.c
> @@ -0,0 +1,190 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2021 Joe Lawrence <joe.lawrence@redhat.com>
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/cache.h>
> +#include <linux/livepatch.h>
> +#include "test_klp_convert.h"
> +
> +/* Small global */
> +int *p_global_small = &global_small;
> +
> +/* Small global (const) */
> +// .rela.data.rel.ro, .rela.rodata supported ???:
> +int * const p_const_global_small = &const_global_small;
> +
> +/* Small file-static */
> +static int *p_static_small = &static_small;
> +
> +/* Small file-static (constant) */
> +static int * const p_static_const_small = &static_const_small;
> +
> +/* Large global */
> +int *p_global_large[4] = {
> + &global_large[0], &global_large[1],
> + &global_large[2], &global_large[3],
> +};
> +
> +/* Large global (const) */
> +// .rela.data.rel.ro, .rela.rodata supported ???:
> +int * const p_const_global_large[4] = {
> + &const_global_large[0], &const_global_large[1],
> + &const_global_large[2], &const_global_large[3],
> +};
> +
> +/* Large file-static global */
> +static int *p_static_large[4] = {
> + &static_large[0], &static_large[1],
> + &static_large[2], &static_large[3],
> +};
> +
> +/* Large file-static (const) */
> +static int * const p_static_const_large[4] = {
> + &static_const_large[0], &static_const_large[1],
> + &static_const_large[2], &static_const_large[3],
> +};
> +
> +// .rela.data.rel.ro, .rela.rodata supported ???:
> +static int * __ro_after_init p_static_ro_after_init = &static_ro_after_init;
> +static int * __read_mostly p_static_read_mostly = &static_read_mostly;
This started getting a bit repetitive, and maybe belongs to its own set
of klp-convert unit tests (as the selftests seem closer to integration
type tests).
Anyway, I left in the .rela.<read-only> type relocations as mentioned in
the [RFC PATCH v6 03/12] livepatch: Add klp-convert tool [1]. We can
talk about whether such sections should be supported over there.
As for this test, it currently crashes ppc64le as it generates a late
klp-relocation type R_PPC64_ADDR64 in a section that was marked RO.
(IIRC such ppc64le data relocations to other .rela.<text> sections are
safe as they aren't marked RO.)
[1] https://lore.kernel.org/lkml/Yg0qgtSFNQx5Mo1i@redhat.com/
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread
* [RFC PATCH v6 12/12] livepatch/selftests: add static keys test
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (10 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 11/12] livepatch/selftests: add data relocations test Joe Lawrence
@ 2022-02-16 16:39 ` Joe Lawrence
2022-02-16 17:17 ` [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
2023-02-07 12:57 ` Marcos Paulo de Souza
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 16:39 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
Add a livepatch kselftest that exercises klp-convert support for static
keys:
- Use static_branch_(un)likely() on vmlinux-defined keys, forcing
.rela__jump_table klp-relocations for them.
- Use only static_key_enable() on module-defined keys, creating .text
klp-relocations for them.
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
lib/livepatch/Makefile | 2 +
lib/livepatch/test_klp_convert.h | 8 ++
lib/livepatch/test_klp_convert_keys.c | 91 +++++++++++++
lib/livepatch/test_klp_convert_keys_mod.c | 52 +++++++
.../selftests/livepatch/test-livepatch.sh | 127 ++++++++++++++++++
5 files changed, 280 insertions(+)
create mode 100644 lib/livepatch/test_klp_convert_keys.c
create mode 100644 lib/livepatch/test_klp_convert_keys_mod.c
diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile
index da39aaa5c8fc..a3c2ac61387f 100644
--- a/lib/livepatch/Makefile
+++ b/lib/livepatch/Makefile
@@ -11,6 +11,8 @@ obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \
test_klp_convert2.o \
test_klp_convert_data.o \
test_klp_convert_sections.o \
+ test_klp_convert_keys.o \
+ test_klp_convert_keys_mod.o \
test_klp_convert_mod.o \
test_klp_livepatch.o \
test_klp_shadow_vars.o \
diff --git a/lib/livepatch/test_klp_convert.h b/lib/livepatch/test_klp_convert.h
index 08c0f4b1dc6b..97d4c26e4c39 100644
--- a/lib/livepatch/test_klp_convert.h
+++ b/lib/livepatch/test_klp_convert.h
@@ -34,4 +34,12 @@ extern int static_const_local_large[4];
extern int static_ro_after_init;
extern int static_read_mostly;
+/* klp-convert symbols - vmlinux */
+extern struct static_key_false tracepoint_printk_key;
+
+/* klp-convert symbols - test_klp_keys_mod.ko */
+extern struct static_key_true test_klp_true_key;
+extern struct static_key_false test_klp_false_key;
+
+
#endif
diff --git a/lib/livepatch/test_klp_convert_keys.c b/lib/livepatch/test_klp_convert_keys.c
new file mode 100644
index 000000000000..90c20e84a146
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_keys.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+#include <linux/jump_label.h>
+#include "test_klp_convert.h"
+
+/*
+ * Carry our own copy of print_key_status() as we want static key code
+ * patching updates to occur in the livepatch module as well as the
+ * target module that defines the static keys.
+ */
+static void print_key_status(char *msg)
+{
+ pr_info("%s: %s\n", __func__, msg);
+
+ /* static_key_enable() only tests the key value */
+ pr_info("static_key_enabled(&tracepoint_printk_key) is %s\n",
+ static_key_enabled(&tracepoint_printk_key) ? "true" : "false");
+ pr_info("static_key_enabled(&test_klp_true_key) is %s\n",
+ static_key_enabled(&test_klp_true_key) ? "true" : "false");
+ pr_info("static_key_enabled(&test_klp_false_key) is %s\n",
+ static_key_enabled(&test_klp_false_key) ? "true" : "false");
+
+ /*
+ * static_branch_(un)likely() requires code patching when the
+ * key value changes
+ */
+ pr_info("static_branch_unlikely(&tracepoint_printk_key) is %s\n",
+ static_branch_unlikely(&tracepoint_printk_key) ? "true" : "false");
+}
+
+/*
+ * sysfs interface to poke the key
+ */
+static bool enable_false_key;
+static int set_enable_false_key(const char *val, const struct kernel_param *kp)
+{
+ print_key_status("set_enable_false_key start");
+ static_branch_enable(&test_klp_false_key);
+ print_key_status("set_enable_false_key enabling test_klp_false_key");
+
+ return 0;
+}
+module_param_call(enable_false_key, set_enable_false_key, NULL,
+ &enable_false_key, 0644);
+MODULE_PARM_DESC(enable_false_key, "Static branch enable");
+
+
+static struct klp_func funcs[] = {
+ { }
+};
+
+static struct klp_object objs[] = {
+ {
+ .name = "test_klp_convert_keys_mod",
+ .funcs = funcs,
+ }, {}
+};
+
+static struct klp_patch patch = {
+ .mod = THIS_MODULE,
+ .objs = objs,
+};
+
+static int test_klp_convert_keys_init(void)
+{
+ int ret;
+
+ ret = klp_enable_patch(&patch);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static void test_klp_convert_keys_exit(void)
+{
+}
+
+module_init(test_klp_convert_keys_init);
+module_exit(test_klp_convert_keys_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: static keys");
+MODULE_INFO(livepatch, "Y");
diff --git a/lib/livepatch/test_klp_convert_keys_mod.c b/lib/livepatch/test_klp_convert_keys_mod.c
new file mode 100644
index 000000000000..7b11c2da09c9
--- /dev/null
+++ b/lib/livepatch/test_klp_convert_keys_mod.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2020 Joe Lawrence <joe.lawrence@redhat.com>
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/jump_label.h>
+
+static DEFINE_STATIC_KEY_TRUE(test_klp_true_key);
+static DEFINE_STATIC_KEY_FALSE(test_klp_false_key);
+
+static void print_key_status(char *msg)
+{
+ pr_info("%s: %s\n", __func__, msg);
+
+ /* static_key_enable() only tests the key value */
+ pr_info("static_key_enabled(&test_klp_true_key) is %s\n",
+ static_key_enabled(&test_klp_true_key) ? "true" : "false");
+ pr_info("static_key_enabled(&test_klp_false_key) is %s\n",
+ static_key_enabled(&test_klp_false_key) ? "true" : "false");
+
+ /*
+ * static_branch_(un)likely() requires code patching when the
+ * key value changes
+ */
+ pr_info("static_branch_likely(&test_klp_true_key) is %s\n",
+ static_branch_likely(&test_klp_true_key) ? "true" : "false");
+ pr_info("static_branch_unlikely(&test_klp_false_key) is %s\n",
+ static_branch_unlikely(&test_klp_false_key) ? "true" : "false");
+}
+
+static int test_klp_keys_mod_init(void)
+{
+ print_key_status("initial conditions");
+ static_branch_disable(&test_klp_true_key);
+ print_key_status("disabled test_klp_true_key");
+
+ return 0;
+}
+
+static void test_klp_keys_mod_exit(void)
+{
+ print_key_status("unloading conditions");
+}
+
+module_init(test_klp_keys_mod_init);
+module_exit(test_klp_keys_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
+MODULE_DESCRIPTION("Livepatch test: static keys target module");
diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index e3e2f59152e1..b32e981df7a1 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -11,6 +11,8 @@ MOD_KLP_CONVERT1=test_klp_convert1
MOD_KLP_CONVERT2=test_klp_convert2
MOD_KLP_CONVERT_DATA=test_klp_convert_data
MOD_KLP_CONVERT_SECTIONS=test_klp_convert_sections
+MOD_KLP_CONVERT_KEYS_MOD=test_klp_convert_keys_mod
+MOD_KLP_CONVERT_KEYS=test_klp_convert_keys
setup_config
@@ -437,4 +439,129 @@ livepatch: '$MOD_KLP_CONVERT_DATA': unpatching complete
% rmmod $MOD_KLP_CONVERT_MOD"
+# TEST: klp-convert static keys
+# - load a module which defines static keys, updates one of the keys on
+# load (forcing jump table patching)
+# - load a livepatch that references the same keys, resolved by
+# klp-convert tool
+# - poke the livepatch sysfs interface to update one of the key (forcing
+# jump table patching again)
+# - disable and unload the livepatch
+# - remove the module
+
+start_test "klp-convert static keys"
+
+load_mod $MOD_KLP_CONVERT_KEYS_MOD
+load_lp $MOD_KLP_CONVERT_KEYS
+
+echo 1 > /sys/module/$MOD_KLP_CONVERT_KEYS/parameters/enable_false_key
+
+disable_lp $MOD_KLP_CONVERT_KEYS
+unload_lp $MOD_KLP_CONVERT_KEYS
+unload_mod $MOD_KLP_CONVERT_KEYS_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_KEYS_MOD
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: initial conditions
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: disabled test_klp_true_key
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is false
+% modprobe $MOD_KLP_CONVERT_KEYS
+livepatch: enabling patch '$MOD_KLP_CONVERT_KEYS'
+livepatch: '$MOD_KLP_CONVERT_KEYS': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': starting patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': completing patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': patching complete
+$MOD_KLP_CONVERT_KEYS: print_key_status: set_enable_false_key start
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS: static_branch_unlikely(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: print_key_status: set_enable_false_key enabling test_klp_false_key
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_false_key) is true
+$MOD_KLP_CONVERT_KEYS: static_branch_unlikely(&tracepoint_printk_key) is false
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT_KEYS/enabled
+livepatch: '$MOD_KLP_CONVERT_KEYS': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': unpatching complete
+% rmmod $MOD_KLP_CONVERT_KEYS
+% rmmod $MOD_KLP_CONVERT_KEYS_MOD
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: unloading conditions
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is true"
+
+
+# TEST: klp-convert static keys (late module patching)
+# - load a module which defines static keys, updates one of the keys on
+# load (forcing jump table patching)
+# - load a livepatch that references the same keys, resolved by
+# klp-convert tool
+# - poke the livepatch sysfs interface to update one of the key (forcing
+# jump table patching again)
+# - disable and unload the livepatch
+# - remove the module
+
+start_test "klp-convert static keys (late module patching)"
+
+load_lp $MOD_KLP_CONVERT_KEYS
+load_mod $MOD_KLP_CONVERT_KEYS_MOD
+
+echo 1 > /sys/module/$MOD_KLP_CONVERT_KEYS/parameters/enable_false_key
+
+disable_lp $MOD_KLP_CONVERT_KEYS
+unload_lp $MOD_KLP_CONVERT_KEYS
+unload_mod $MOD_KLP_CONVERT_KEYS_MOD
+
+check_result "% modprobe $MOD_KLP_CONVERT_KEYS
+livepatch: enabling patch '$MOD_KLP_CONVERT_KEYS'
+livepatch: '$MOD_KLP_CONVERT_KEYS': initializing patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': starting patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': completing patching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': patching complete
+% modprobe $MOD_KLP_CONVERT_KEYS_MOD
+livepatch: applying patch '$MOD_KLP_CONVERT_KEYS' to loading module '$MOD_KLP_CONVERT_KEYS_MOD'
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: initial conditions
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: disabled test_klp_true_key
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS: print_key_status: set_enable_false_key start
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_false_key) is false
+$MOD_KLP_CONVERT_KEYS: static_branch_unlikely(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: print_key_status: set_enable_false_key enabling test_klp_false_key
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&tracepoint_printk_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS: static_key_enabled(&test_klp_false_key) is true
+$MOD_KLP_CONVERT_KEYS: static_branch_unlikely(&tracepoint_printk_key) is false
+% echo 0 > /sys/kernel/livepatch/$MOD_KLP_CONVERT_KEYS/enabled
+livepatch: '$MOD_KLP_CONVERT_KEYS': initializing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': starting unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': completing unpatching transition
+livepatch: '$MOD_KLP_CONVERT_KEYS': unpatching complete
+% rmmod $MOD_KLP_CONVERT_KEYS
+% rmmod $MOD_KLP_CONVERT_KEYS_MOD
+$MOD_KLP_CONVERT_KEYS_MOD: print_key_status: unloading conditions
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_key_enabled(&test_klp_false_key) is true
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_likely(&test_klp_true_key) is false
+$MOD_KLP_CONVERT_KEYS_MOD: static_branch_unlikely(&test_klp_false_key) is true"
+
+
exit 0
--
2.26.3
^ permalink raw reply related [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 00/12] livepatch: klp-convert tool
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (11 preceding siblings ...)
2022-02-16 16:39 ` [RFC PATCH v6 12/12] livepatch/selftests: add static keys test Joe Lawrence
@ 2022-02-16 17:17 ` Joe Lawrence
2023-02-07 12:57 ` Marcos Paulo de Souza
13 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2022-02-16 17:17 UTC (permalink / raw)
To: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:28AM -0500, Joe Lawrence wrote:
>
> [ ... snip ... ]
>
> lib/livepatch/Makefile | 12 +
> lib/livepatch/test_klp_convert.h | 45 +
> lib/livepatch/test_klp_convert1.c | 121 +++
> lib/livepatch/test_klp_convert2.c | 110 +++
> lib/livepatch/test_klp_convert_data.c | 190 ++++
> lib/livepatch/test_klp_convert_keys.c | 91 ++
> lib/livepatch/test_klp_convert_keys_mod.c | 52 +
> lib/livepatch/test_klp_convert_mod_a.c | 31 +
> lib/livepatch/test_klp_convert_mod_b.c | 19 +
> lib/livepatch/test_klp_convert_mod_c.c | 36 +
> lib/livepatch/test_klp_convert_sections.c | 120 +++
A general (selftests) question: is there any build mechanism in the
kernel tree that is used to *expect* build failure?
Under certain circumstances, we would need klp-convert to fail and it
would be helpful to test for that. At the moment I am considered out of
tree tests that could exercise the code this way, but definitely prefer
anything that is already in-tree.
Thanks,
-- Joe
^ permalink raw reply [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 00/12] livepatch: klp-convert tool
2022-02-16 16:39 [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
` (12 preceding siblings ...)
2022-02-16 17:17 ` [RFC PATCH v6 00/12] livepatch: klp-convert tool Joe Lawrence
@ 2023-02-07 12:57 ` Marcos Paulo de Souza
2023-02-07 15:54 ` Joe Lawrence
13 siblings, 1 reply; 28+ messages in thread
From: Marcos Paulo de Souza @ 2023-02-07 12:57 UTC (permalink / raw)
To: Joe Lawrence; +Cc: live-patching, linux-kernel, linux-kbuild
On Wed, Feb 16, 2022 at 11:39:28AM -0500, Joe Lawrence wrote:
> This mostly a rebase update of the livepatch klp-convert tool used to
> generate klp-relocation types (explained in the summary below).
>
> I'm marking this as an RFC as it hasn't been extensively tested for all
> livepatch supported arches. There are may be a few symbol annotation
> changes pending what may be implemented for the FGKASLR patchset, I've
> left a few TODO and // question? marks in the code, etc. At the same
> time, I think "CET/IBT support and live-patches" highlighted a potential
> need for this tooling, so I'm posting it in its current format for
> discussion. I'll reply to individual patches to highlight a few points
> of interest.
>
>
> Summary
> -------
>
> Livepatches may use symbols which are not contained in its own scope,
> and, because of that, may end up compiled with relocations that will
> only be resolved during module load. Yet, when the referenced symbols
> are not exported, solving this relocation requires information on the
> object that holds the symbol (either vmlinux or modules) and its
> position inside the object, as an object may contain multiple symbols
> with the same name. Providing such information must be done accordingly
> to what is specified in Documentation/livepatch/module-elf-format.txt.
>
> Currently, there is no trivial way to embed the required information as
> requested in the final livepatch elf object. klp-convert solves this
> problem in two different forms: (i) by relying on a symbol map, which is
> built during kernel compilation, to automatically infer the relocation
> targeted symbol, and, when such inference is not possible (ii) by using
> annotations in the elf object to convert the relocation accordingly to
> the specification, enabling it to be handled by the livepatch loader.
>
> Given the above, add support for symbol mapping in the form of a
> symbols.klp file; add klp-convert tool; integrate klp-convert tool into
> kbuild; make livepatch modules discernible during kernel compilation
> pipeline; add data-structure and macros to enable users to annotate
> livepatch source code; make modpost stage compatible with livepatches;
> update livepatch-sample and update documentation.
>
> The patch was tested under three use-cases:
>
> use-case 1: There is a relocation in the lp that can be automatically
> resolved by klp-convert. For example. see the saved_command_line
> variable in lib/livepatch/test_klp_convert2.c.
>
> use-case 2: There is a relocation in the lp that cannot be automatically
> resolved, as the name of the respective symbol appears in multiple
> objects. The livepatch contains an annotation to enable a correct
> relocation. See the KLP_MODULE_RELOC / KLP_SYMPOS annotation sections
> in lib/livepatch/test_klp_convert{1,2}.c.
>
> use-case 3: There is a relocation in the lp that cannot be automatically
> resolved similarly as 2, but no annotation was provided in the
> livepatch, triggering an error during compilation. Reproducible by
> removing the KLP_MODULE_RELOC / KLP_SYMPOS annotation sections in
> lib/livepatch/test_klp_convert{1,2}.c.
>
> Selftests have been added to exercise these klp-convert use-cases
> through several tests.
>
>
> Branches
> --------
>
>
> Previous versions
> -----------------
>
> RFC:
> https://lore.kernel.org/lkml/cover.1477578530.git.jpoimboe@redhat.com/
> v2:
> https://lore.kernel.org/lkml/f52d29f7-7d1b-ad3d-050b-a9fa8878faf2@redhat.com/
> v3:
> https://lore.kernel.org/lkml/20190410155058.9437-1-joe.lawrence@redhat.com/
> v4:
> https://lore.kernel.org/lkml/20190509143859.9050-1-joe.lawrence@redhat.com/
> v5:
> (not posted)
> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v5-devel
> v6:
> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v6
> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v6-devel
Hi Joe,
I send reviews to some patches of the v6 batch, but there is currently a v7 in
your github profile. I believe that I sent Rb for patches that are the same
between versions.
The current version is almost one year older already. Do you plan to send v7
soon?
Thanks a lot!
Marcos
>
>
> Summary of changes in v5
> ------------------------
>
> [For/from Masahiro]
> - rename Symbols.list to symbols.klp
> - remove HOST_EXTRACFLAGS from klp-convert build
> - kbuild tweaks from Masahiro Yamada
> - SPDX instead of the license boilerplate
>
> [Joe]
> - a bunch of small checkpatch, clang-check fixes
> - klp-convert: account for symbols shared across sections
> - klp-convert: sympos endianness for cross-compile
> - klp-convert: implement rela section support list
> - klp-convert: update group sections sh_link
> - klp-convert: flag annotations without relocations
> - klp-convert: allow .rela__jump_table to vmlinux
> - livepatch/selftests: Add __asm__ symbol renaming examples
> - livepatch/selftests: test multiple sections
> - livepatch/selftests: add static keys test
>
> [Miroslav]
> - klp-convert: use _safe list traversals only when required
> - klp-convert: separate rela conversation from removal
>
>
> Summary of changes in v6
> ------------------------
>
> [For/from Christophe]
> - klp-convert: Support for ppc32 ELF files
>
> [Joe]
> - livepatch/selftests: add data relocations test
> - klp-convert: move relas to klp_rela_sec tail
> - rebase for v5.17-rc1
>
>
> Joao Moreira (2):
> kbuild: Support for symbols.klp creation
> documentation: Update on livepatch elf format
>
> Joe Lawrence (5):
> livepatch/selftests: add klp-convert
> livepatch/selftests: test multiple sections
> livepatch/selftests: add __asm__ symbol renaming examples
> livepatch/selftests: add data relocations test
> livepatch/selftests: add static keys test
>
> Josh Poimboeuf (5):
> livepatch: Create and include UAPI headers
> livepatch: Add klp-convert tool
> livepatch: Add klp-convert annotation helpers
> modpost: Integrate klp-convert
> livepatch: Add sample livepatch module
>
> .gitignore | 2 +
> Documentation/dontdiff | 1 +
> Documentation/livepatch/livepatch.rst | 3 +
> Documentation/livepatch/module-elf-format.rst | 42 +-
> MAINTAINERS | 2 +
> Makefile | 12 +-
> include/linux/livepatch.h | 13 +
> include/uapi/linux/livepatch.h | 25 +
> kernel/livepatch/core.c | 4 +-
> lib/livepatch/Makefile | 12 +
> lib/livepatch/test_klp_convert.h | 45 +
> lib/livepatch/test_klp_convert1.c | 121 +++
> lib/livepatch/test_klp_convert2.c | 110 +++
> lib/livepatch/test_klp_convert_data.c | 190 ++++
> lib/livepatch/test_klp_convert_keys.c | 91 ++
> lib/livepatch/test_klp_convert_keys_mod.c | 52 +
> lib/livepatch/test_klp_convert_mod_a.c | 31 +
> lib/livepatch/test_klp_convert_mod_b.c | 19 +
> lib/livepatch/test_klp_convert_mod_c.c | 36 +
> lib/livepatch/test_klp_convert_sections.c | 120 +++
> samples/livepatch/Makefile | 1 +
> .../livepatch/livepatch-annotated-sample.c | 93 ++
> scripts/Makefile | 1 +
> scripts/Makefile.modfinal | 38 +-
> scripts/Makefile.modpost | 5 +
> scripts/livepatch/.gitignore | 1 +
> scripts/livepatch/Makefile | 5 +
> scripts/livepatch/elf.c | 813 ++++++++++++++++
> scripts/livepatch/elf.h | 74 ++
> scripts/livepatch/klp-convert.c | 885 ++++++++++++++++++
> scripts/livepatch/klp-convert.h | 47 +
> scripts/livepatch/list.h | 391 ++++++++
> scripts/mod/modpost.c | 28 +-
> scripts/mod/modpost.h | 1 +
> .../selftests/livepatch/test-livepatch.sh | 405 ++++++++
> 35 files changed, 3708 insertions(+), 11 deletions(-)
> create mode 100644 include/uapi/linux/livepatch.h
> create mode 100644 lib/livepatch/test_klp_convert.h
> create mode 100644 lib/livepatch/test_klp_convert1.c
> create mode 100644 lib/livepatch/test_klp_convert2.c
> create mode 100644 lib/livepatch/test_klp_convert_data.c
> create mode 100644 lib/livepatch/test_klp_convert_keys.c
> create mode 100644 lib/livepatch/test_klp_convert_keys_mod.c
> create mode 100644 lib/livepatch/test_klp_convert_mod_a.c
> create mode 100644 lib/livepatch/test_klp_convert_mod_b.c
> create mode 100644 lib/livepatch/test_klp_convert_mod_c.c
> create mode 100644 lib/livepatch/test_klp_convert_sections.c
> create mode 100644 samples/livepatch/livepatch-annotated-sample.c
> create mode 100644 scripts/livepatch/.gitignore
> create mode 100644 scripts/livepatch/Makefile
> create mode 100644 scripts/livepatch/elf.c
> create mode 100644 scripts/livepatch/elf.h
> create mode 100644 scripts/livepatch/klp-convert.c
> create mode 100644 scripts/livepatch/klp-convert.h
> create mode 100644 scripts/livepatch/list.h
>
> --
> 2.26.3
>
^ permalink raw reply [flat|nested] 28+ messages in thread* Re: [RFC PATCH v6 00/12] livepatch: klp-convert tool
2023-02-07 12:57 ` Marcos Paulo de Souza
@ 2023-02-07 15:54 ` Joe Lawrence
0 siblings, 0 replies; 28+ messages in thread
From: Joe Lawrence @ 2023-02-07 15:54 UTC (permalink / raw)
To: Marcos Paulo de Souza; +Cc: live-patching, linux-kernel, linux-kbuild
On 2/7/23 07:57, Marcos Paulo de Souza wrote:
> On Wed, Feb 16, 2022 at 11:39:28AM -0500, Joe Lawrence wrote:
>> This mostly a rebase update of the livepatch klp-convert tool used to
>> generate klp-relocation types (explained in the summary below).
>>
>> I'm marking this as an RFC as it hasn't been extensively tested for all
>> livepatch supported arches. There are may be a few symbol annotation
>> changes pending what may be implemented for the FGKASLR patchset, I've
>> left a few TODO and // question? marks in the code, etc. At the same
>> time, I think "CET/IBT support and live-patches" highlighted a potential
>> need for this tooling, so I'm posting it in its current format for
>> discussion. I'll reply to individual patches to highlight a few points
>> of interest.
>>
>>
>> Summary
>> -------
>>
>> Livepatches may use symbols which are not contained in its own scope,
>> and, because of that, may end up compiled with relocations that will
>> only be resolved during module load. Yet, when the referenced symbols
>> are not exported, solving this relocation requires information on the
>> object that holds the symbol (either vmlinux or modules) and its
>> position inside the object, as an object may contain multiple symbols
>> with the same name. Providing such information must be done accordingly
>> to what is specified in Documentation/livepatch/module-elf-format.txt.
>>
>> Currently, there is no trivial way to embed the required information as
>> requested in the final livepatch elf object. klp-convert solves this
>> problem in two different forms: (i) by relying on a symbol map, which is
>> built during kernel compilation, to automatically infer the relocation
>> targeted symbol, and, when such inference is not possible (ii) by using
>> annotations in the elf object to convert the relocation accordingly to
>> the specification, enabling it to be handled by the livepatch loader.
>>
>> Given the above, add support for symbol mapping in the form of a
>> symbols.klp file; add klp-convert tool; integrate klp-convert tool into
>> kbuild; make livepatch modules discernible during kernel compilation
>> pipeline; add data-structure and macros to enable users to annotate
>> livepatch source code; make modpost stage compatible with livepatches;
>> update livepatch-sample and update documentation.
>>
>> The patch was tested under three use-cases:
>>
>> use-case 1: There is a relocation in the lp that can be automatically
>> resolved by klp-convert. For example. see the saved_command_line
>> variable in lib/livepatch/test_klp_convert2.c.
>>
>> use-case 2: There is a relocation in the lp that cannot be automatically
>> resolved, as the name of the respective symbol appears in multiple
>> objects. The livepatch contains an annotation to enable a correct
>> relocation. See the KLP_MODULE_RELOC / KLP_SYMPOS annotation sections
>> in lib/livepatch/test_klp_convert{1,2}.c.
>>
>> use-case 3: There is a relocation in the lp that cannot be automatically
>> resolved similarly as 2, but no annotation was provided in the
>> livepatch, triggering an error during compilation. Reproducible by
>> removing the KLP_MODULE_RELOC / KLP_SYMPOS annotation sections in
>> lib/livepatch/test_klp_convert{1,2}.c.
>>
>> Selftests have been added to exercise these klp-convert use-cases
>> through several tests.
>>
>>
>> Branches
>> --------
>>
>>
>> Previous versions
>> -----------------
>>
>> RFC:
>> https://lore.kernel.org/lkml/cover.1477578530.git.jpoimboe@redhat.com/
>> v2:
>> https://lore.kernel.org/lkml/f52d29f7-7d1b-ad3d-050b-a9fa8878faf2@redhat.com/
>> v3:
>> https://lore.kernel.org/lkml/20190410155058.9437-1-joe.lawrence@redhat.com/
>> v4:
>> https://lore.kernel.org/lkml/20190509143859.9050-1-joe.lawrence@redhat.com/
>> v5:
>> (not posted)
>> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v5-devel
>> v6:
>> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v6
>> https://github.com/joe-lawrence/klp-convert-tree/tree/klp-convert-v6-devel
>
> Hi Joe,
>
> I send reviews to some patches of the v6 batch, but there is currently a v7 in
> your github profile. I believe that I sent Rb for patches that are the same
> between versions.
>
> The current version is almost one year older already. Do you plan to send v7
> soon?
>
Hi Marcos,
Thanks for the reviews and indeed, it has been a while since v6.
For v7, I would like to rebase on top of v6.2 so it includes the recent
x86/ppc64le relocation fixes from Song/Josh.
There are still a fair number of design questions that I have.. but a
fresh version will be much easier to test and review. I'll try to get
it posted in the new few weeks.
--
Joe
^ permalink raw reply [flat|nested] 28+ messages in thread