[PATCH v1 0/6] Miscellaneous cleanups

[PATCH v1 0/6] Miscellaneous cleanups

[Christophe Leroy]

This series applies on top of my series "Allocate module text and data separately" v4.

It contains some cleanups to the module core.

First patch brings back signature.c out of kernel/module/ as this file
is not directly linked to modules. Ideally this change should be squashed
in first patch of Aaron's series.

Second patch moves Kconfig's module related stuff in a dedicated Kconfig.

Patches 3-6 do some cleanup around the settling of modules's layout page flags.

Christophe Leroy (6):
  module: Have kernel/module/ dedicated to CONFIG_MODULES
  module: Move module's Kconfig item in kernel/module/
  module: Make module_enable_x() independent of
    CONFIG_ARCH_HAS_STRICT_MODULE_RWX
  module: Move module_enable_x() and frob_text() in strict_rwx.c
  module: Rework layout alignment to avoid BUG_ON()s
  module: Rename debug_align() as strict_align()

 init/Kconfig                                  | 286 +-----------------
 kernel/Makefile                               |   3 +-
 kernel/module/Kconfig                         | 286 ++++++++++++++++++
 kernel/module/Makefile                        |   6 +-
 kernel/module/internal.h                      |  26 +-
 kernel/module/kallsyms.c                      |   4 +-
 kernel/module/main.c                          |  58 +---
 kernel/module/strict_rwx.c                    |  76 ++++-
 .../signature.c => module_signature.c}        |   0
 9 files changed, 377 insertions(+), 368 deletions(-)
 create mode 100644 kernel/module/Kconfig
 rename kernel/{module/signature.c => module_signature.c} (100%)

-- 
2.34.1

[PATCH v1 1/6] module: Have kernel/module/ dedicated to CONFIG_MODULES

[Christophe Leroy]

Move signature.c back into kernel/ because it is used by
more than modules.

Then build kernel/module/ only when CONFIG_MODULES is selected.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
Ideally this patch should be squashed in Aaron's series patch 1
---
 kernel/Makefile                                   | 3 ++-
 kernel/module/Makefile                            | 5 +----
 kernel/{module/signature.c => module_signature.c} | 0
 3 files changed, 3 insertions(+), 5 deletions(-)
 rename kernel/{module/signature.c => module_signature.c} (100%)

diff --git a/kernel/Makefile b/kernel/Makefile
index 04cb6932c0d3..717075b65deb 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -52,7 +52,7 @@ obj-y += rcu/
 obj-y += livepatch/
 obj-y += dma/
 obj-y += entry/
-obj-y += module/
+obj-$(CONFIG_MODULES) += module/
 
 obj-$(CONFIG_KCMP) += kcmp.o
 obj-$(CONFIG_FREEZER) += freezer.o
@@ -66,6 +66,7 @@ ifneq ($(CONFIG_SMP),y)
 obj-y += up.o
 endif
 obj-$(CONFIG_UID16) += uid16.o
+obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
 obj-$(CONFIG_CRASH_CORE) += crash_core.o
diff --git a/kernel/module/Makefile b/kernel/module/Makefile
index b57953bd47eb..5fe90d246fcc 100644
--- a/kernel/module/Makefile
+++ b/kernel/module/Makefile
@@ -7,12 +7,10 @@
 # and produce insane amounts of uninteresting coverage.
 KCOV_INSTRUMENT_main.o := n
 
-obj-$(CONFIG_MODULES) += main.o
+obj-y += main.o
 obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o
 obj-$(CONFIG_MODULE_SIG) += signing.o
-obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o
 obj-$(CONFIG_LIVEPATCH) += livepatch.o
-ifdef CONFIG_MODULES
 obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
 obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o
 obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o
@@ -20,4 +18,3 @@ obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_PROC_FS) += procfs.o
 obj-$(CONFIG_SYSFS) += sysfs.o
 obj-$(CONFIG_MODVERSIONS) += version.o
-endif
diff --git a/kernel/module/signature.c b/kernel/module_signature.c
similarity index 100%
rename from kernel/module/signature.c
rename to kernel/module_signature.c
-- 
2.34.1

[PATCH v1 2/6] module: Move module's Kconfig item in kernel/module/

[Christophe Leroy]

In init/Kconfig, the part dedicated to modules is quite large.

Move it into a dedicated Kconfig in kernel/module/

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 init/Kconfig          | 286 +-----------------------------------------
 kernel/module/Kconfig | 286 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 287 insertions(+), 285 deletions(-)
 create mode 100644 kernel/module/Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index e9119bf54b1f..1c8828493385 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2064,291 +2064,7 @@ config MODULE_SIG_FORMAT
 	def_bool n
 	select SYSTEM_DATA_VERIFICATION
 
-menuconfig MODULES
-	bool "Enable loadable module support"
-	modules
-	help
-	  Kernel modules are small pieces of compiled code which can
-	  be inserted in the running kernel, rather than being
-	  permanently built into the kernel.  You use the "modprobe"
-	  tool to add (and sometimes remove) them.  If you say Y here,
-	  many parts of the kernel can be built as modules (by
-	  answering M instead of Y where indicated): this is most
-	  useful for infrequently used options which are not required
-	  for booting.  For more information, see the man pages for
-	  modprobe, lsmod, modinfo, insmod and rmmod.
-
-	  If you say Y here, you will need to run "make
-	  modules_install" to put the modules under /lib/modules/
-	  where modprobe can find them (you may need to be root to do
-	  this).
-
-	  If unsure, say Y.
-
-if MODULES
-
-config MODULE_FORCE_LOAD
-	bool "Forced module loading"
-	default n
-	help
-	  Allow loading of modules without version information (ie. modprobe
-	  --force).  Forced module loading sets the 'F' (forced) taint flag and
-	  is usually a really bad idea.
-
-config MODULE_UNLOAD
-	bool "Module unloading"
-	help
-	  Without this option you will not be able to unload any
-	  modules (note that some modules may not be unloadable
-	  anyway), which makes your kernel smaller, faster
-	  and simpler.  If unsure, say Y.
-
-config MODULE_FORCE_UNLOAD
-	bool "Forced module unloading"
-	depends on MODULE_UNLOAD
-	help
-	  This option allows you to force a module to unload, even if the
-	  kernel believes it is unsafe: the kernel will remove the module
-	  without waiting for anyone to stop using it (using the -f option to
-	  rmmod).  This is mainly for kernel developers and desperate users.
-	  If unsure, say N.
-
-config MODVERSIONS
-	bool "Module versioning support"
-	help
-	  Usually, you have to use modules compiled with your kernel.
-	  Saying Y here makes it sometimes possible to use modules
-	  compiled for different kernels, by adding enough information
-	  to the modules to (hopefully) spot any changes which would
-	  make them incompatible with the kernel you are running.  If
-	  unsure, say N.
-
-config ASM_MODVERSIONS
-	bool
-	default HAVE_ASM_MODVERSIONS && MODVERSIONS
-	help
-	  This enables module versioning for exported symbols also from
-	  assembly. This can be enabled only when the target architecture
-	  supports it.
-
-config MODULE_REL_CRCS
-	bool
-	depends on MODVERSIONS
-
-config MODULE_SRCVERSION_ALL
-	bool "Source checksum for all modules"
-	help
-	  Modules which contain a MODULE_VERSION get an extra "srcversion"
-	  field inserted into their modinfo section, which contains a
-    	  sum of the source files which made it.  This helps maintainers
-	  see exactly which source was used to build a module (since
-	  others sometimes change the module source without updating
-	  the version).  With this option, such a "srcversion" field
-	  will be created for all modules.  If unsure, say N.
-
-config MODULE_SIG
-	bool "Module signature verification"
-	select MODULE_SIG_FORMAT
-	help
-	  Check modules for valid signatures upon load: the signature
-	  is simply appended to the module. For more information see
-	  <file:Documentation/admin-guide/module-signing.rst>.
-
-	  Note that this option adds the OpenSSL development packages as a
-	  kernel build dependency so that the signing tool can use its crypto
-	  library.
-
-	  You should enable this option if you wish to use either
-	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
-	  another LSM - otherwise unsigned modules will be loadable regardless
-	  of the lockdown policy.
-
-	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
-	  module DOES NOT get stripped after being signed.  This includes the
-	  debuginfo strip done by some packagers (such as rpmbuild) and
-	  inclusion into an initramfs that wants the module size reduced.
-
-config MODULE_SIG_FORCE
-	bool "Require modules to be validly signed"
-	depends on MODULE_SIG
-	help
-	  Reject unsigned modules or signed modules for which we don't have a
-	  key.  Without this, such modules will simply taint the kernel.
-
-config MODULE_SIG_ALL
-	bool "Automatically sign all modules"
-	default y
-	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
-	help
-	  Sign all modules during make modules_install. Without this option,
-	  modules must be signed manually, using the scripts/sign-file tool.
-
-comment "Do not forget to sign required modules with scripts/sign-file"
-	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
-
-choice
-	prompt "Which hash algorithm should modules be signed with?"
-	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
-	help
-	  This determines which sort of hashing algorithm will be used during
-	  signature generation.  This algorithm _must_ be built into the kernel
-	  directly so that signature verification can take place.  It is not
-	  possible to load a signed module containing the algorithm to check
-	  the signature on that module.
-
-config MODULE_SIG_SHA1
-	bool "Sign modules with SHA-1"
-	select CRYPTO_SHA1
-
-config MODULE_SIG_SHA224
-	bool "Sign modules with SHA-224"
-	select CRYPTO_SHA256
-
-config MODULE_SIG_SHA256
-	bool "Sign modules with SHA-256"
-	select CRYPTO_SHA256
-
-config MODULE_SIG_SHA384
-	bool "Sign modules with SHA-384"
-	select CRYPTO_SHA512
-
-config MODULE_SIG_SHA512
-	bool "Sign modules with SHA-512"
-	select CRYPTO_SHA512
-
-endchoice
-
-config MODULE_SIG_HASH
-	string
-	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
-	default "sha1" if MODULE_SIG_SHA1
-	default "sha224" if MODULE_SIG_SHA224
-	default "sha256" if MODULE_SIG_SHA256
-	default "sha384" if MODULE_SIG_SHA384
-	default "sha512" if MODULE_SIG_SHA512
-
-choice
-	prompt "Module compression mode"
-	help
-	  This option allows you to choose the algorithm which will be used to
-	  compress modules when 'make modules_install' is run. (or, you can
-	  choose to not compress modules at all.)
-
-	  External modules will also be compressed in the same way during the
-	  installation.
-
-	  For modules inside an initrd or initramfs, it's more efficient to
-	  compress the whole initrd or initramfs instead.
-
-	  This is fully compatible with signed modules.
-
-	  Please note that the tool used to load modules needs to support the
-	  corresponding algorithm. module-init-tools MAY support gzip, and kmod
-	  MAY support gzip, xz and zstd.
-
-	  Your build system needs to provide the appropriate compression tool
-	  to compress the modules.
-
-	  If in doubt, select 'None'.
-
-config MODULE_COMPRESS_NONE
-	bool "None"
-	help
-	  Do not compress modules. The installed modules are suffixed
-	  with .ko.
-
-config MODULE_COMPRESS_GZIP
-	bool "GZIP"
-	help
-	  Compress modules with GZIP. The installed modules are suffixed
-	  with .ko.gz.
-
-config MODULE_COMPRESS_XZ
-	bool "XZ"
-	help
-	  Compress modules with XZ. The installed modules are suffixed
-	  with .ko.xz.
-
-config MODULE_COMPRESS_ZSTD
-	bool "ZSTD"
-	help
-	  Compress modules with ZSTD. The installed modules are suffixed
-	  with .ko.zst.
-
-endchoice
-
-config MODULE_DECOMPRESS
-	bool "Support in-kernel module decompression"
-	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
-	select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
-	select XZ_DEC if MODULE_COMPRESS_XZ
-	help
-
-	  Support for decompressing kernel modules by the kernel itself
-	  instead of relying on userspace to perform this task. Useful when
-	  load pinning security policy is enabled.
-
-	  If unsure, say N.
-
-config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
-	bool "Allow loading of modules with missing namespace imports"
-	help
-	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
-	  a namespace. A module that makes use of a symbol exported with such a
-	  namespace is required to import the namespace via MODULE_IMPORT_NS().
-	  There is no technical reason to enforce correct namespace imports,
-	  but it creates consistency between symbols defining namespaces and
-	  users importing namespaces they make use of. This option relaxes this
-	  requirement and lifts the enforcement when loading a module.
-
-	  If unsure, say N.
-
-config MODPROBE_PATH
-	string "Path to modprobe binary"
-	default "/sbin/modprobe"
-	help
-	  When kernel code requests a module, it does so by calling
-	  the "modprobe" userspace utility. This option allows you to
-	  set the path where that binary is found. This can be changed
-	  at runtime via the sysctl file
-	  /proc/sys/kernel/modprobe. Setting this to the empty string
-	  removes the kernel's ability to request modules (but
-	  userspace can still load modules explicitly).
-
-config TRIM_UNUSED_KSYMS
-	bool "Trim unused exported kernel symbols" if EXPERT
-	depends on !COMPILE_TEST
-	help
-	  The kernel and some modules make many symbols available for
-	  other modules to use via EXPORT_SYMBOL() and variants. Depending
-	  on the set of modules being selected in your kernel configuration,
-	  many of those exported symbols might never be used.
-
-	  This option allows for unused exported symbols to be dropped from
-	  the build. In turn, this provides the compiler more opportunities
-	  (especially when using LTO) for optimizing the code and reducing
-	  binary size.  This might have some security advantages as well.
-
-	  If unsure, or if you need to build out-of-tree modules, say N.
-
-config UNUSED_KSYMS_WHITELIST
-	string "Whitelist of symbols to keep in ksymtab"
-	depends on TRIM_UNUSED_KSYMS
-	help
-	  By default, all unused exported symbols will be un-exported from the
-	  build when TRIM_UNUSED_KSYMS is selected.
-
-	  UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
-	  exported at all times, even in absence of in-tree users. The value to
-	  set here is the path to a text file containing the list of symbols,
-	  one per line. The path can be absolute, or relative to the kernel
-	  source tree.
-
-endif # MODULES
-
-config MODULES_TREE_LOOKUP
-	def_bool y
-	depends on PERF_EVENTS || TRACING || CFI_CLANG
+source "kernel/module/Kconfig"
 
 config INIT_ALL_POSSIBLE
 	bool
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
new file mode 100644
index 000000000000..9177cb38ea2e
--- /dev/null
+++ b/kernel/module/Kconfig
@@ -0,0 +1,286 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig MODULES
+	bool "Enable loadable module support"
+	modules
+	help
+	  Kernel modules are small pieces of compiled code which can
+	  be inserted in the running kernel, rather than being
+	  permanently built into the kernel.  You use the "modprobe"
+	  tool to add (and sometimes remove) them.  If you say Y here,
+	  many parts of the kernel can be built as modules (by
+	  answering M instead of Y where indicated): this is most
+	  useful for infrequently used options which are not required
+	  for booting.  For more information, see the man pages for
+	  modprobe, lsmod, modinfo, insmod and rmmod.
+
+	  If you say Y here, you will need to run "make
+	  modules_install" to put the modules under /lib/modules/
+	  where modprobe can find them (you may need to be root to do
+	  this).
+
+	  If unsure, say Y.
+
+if MODULES
+
+config MODULE_FORCE_LOAD
+	bool "Forced module loading"
+	default n
+	help
+	  Allow loading of modules without version information (ie. modprobe
+	  --force).  Forced module loading sets the 'F' (forced) taint flag and
+	  is usually a really bad idea.
+
+config MODULE_UNLOAD
+	bool "Module unloading"
+	help
+	  Without this option you will not be able to unload any
+	  modules (note that some modules may not be unloadable
+	  anyway), which makes your kernel smaller, faster
+	  and simpler.  If unsure, say Y.
+
+config MODULE_FORCE_UNLOAD
+	bool "Forced module unloading"
+	depends on MODULE_UNLOAD
+	help
+	  This option allows you to force a module to unload, even if the
+	  kernel believes it is unsafe: the kernel will remove the module
+	  without waiting for anyone to stop using it (using the -f option to
+	  rmmod).  This is mainly for kernel developers and desperate users.
+	  If unsure, say N.
+
+config MODVERSIONS
+	bool "Module versioning support"
+	help
+	  Usually, you have to use modules compiled with your kernel.
+	  Saying Y here makes it sometimes possible to use modules
+	  compiled for different kernels, by adding enough information
+	  to the modules to (hopefully) spot any changes which would
+	  make them incompatible with the kernel you are running.  If
+	  unsure, say N.
+
+config ASM_MODVERSIONS
+	bool
+	default HAVE_ASM_MODVERSIONS && MODVERSIONS
+	help
+	  This enables module versioning for exported symbols also from
+	  assembly. This can be enabled only when the target architecture
+	  supports it.
+
+config MODULE_REL_CRCS
+	bool
+	depends on MODVERSIONS
+
+config MODULE_SRCVERSION_ALL
+	bool "Source checksum for all modules"
+	help
+	  Modules which contain a MODULE_VERSION get an extra "srcversion"
+	  field inserted into their modinfo section, which contains a
+	  sum of the source files which made it.  This helps maintainers
+	  see exactly which source was used to build a module (since
+	  others sometimes change the module source without updating
+	  the version).  With this option, such a "srcversion" field
+	  will be created for all modules.  If unsure, say N.
+
+config MODULE_SIG
+	bool "Module signature verification"
+	select MODULE_SIG_FORMAT
+	help
+	  Check modules for valid signatures upon load: the signature
+	  is simply appended to the module. For more information see
+	  <file:Documentation/admin-guide/module-signing.rst>.
+
+	  Note that this option adds the OpenSSL development packages as a
+	  kernel build dependency so that the signing tool can use its crypto
+	  library.
+
+	  You should enable this option if you wish to use either
+	  CONFIG_SECURITY_LOCKDOWN_LSM or lockdown functionality imposed via
+	  another LSM - otherwise unsigned modules will be loadable regardless
+	  of the lockdown policy.
+
+	  !!!WARNING!!!  If you enable this option, you MUST make sure that the
+	  module DOES NOT get stripped after being signed.  This includes the
+	  debuginfo strip done by some packagers (such as rpmbuild) and
+	  inclusion into an initramfs that wants the module size reduced.
+
+config MODULE_SIG_FORCE
+	bool "Require modules to be validly signed"
+	depends on MODULE_SIG
+	help
+	  Reject unsigned modules or signed modules for which we don't have a
+	  key.  Without this, such modules will simply taint the kernel.
+
+config MODULE_SIG_ALL
+	bool "Automatically sign all modules"
+	default y
+	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
+	help
+	  Sign all modules during make modules_install. Without this option,
+	  modules must be signed manually, using the scripts/sign-file tool.
+
+comment "Do not forget to sign required modules with scripts/sign-file"
+	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
+
+choice
+	prompt "Which hash algorithm should modules be signed with?"
+	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
+	help
+	  This determines which sort of hashing algorithm will be used during
+	  signature generation.  This algorithm _must_ be built into the kernel
+	  directly so that signature verification can take place.  It is not
+	  possible to load a signed module containing the algorithm to check
+	  the signature on that module.
+
+config MODULE_SIG_SHA1
+	bool "Sign modules with SHA-1"
+	select CRYPTO_SHA1
+
+config MODULE_SIG_SHA224
+	bool "Sign modules with SHA-224"
+	select CRYPTO_SHA256
+
+config MODULE_SIG_SHA256
+	bool "Sign modules with SHA-256"
+	select CRYPTO_SHA256
+
+config MODULE_SIG_SHA384
+	bool "Sign modules with SHA-384"
+	select CRYPTO_SHA512
+
+config MODULE_SIG_SHA512
+	bool "Sign modules with SHA-512"
+	select CRYPTO_SHA512
+
+endchoice
+
+config MODULE_SIG_HASH
+	string
+	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
+	default "sha1" if MODULE_SIG_SHA1
+	default "sha224" if MODULE_SIG_SHA224
+	default "sha256" if MODULE_SIG_SHA256
+	default "sha384" if MODULE_SIG_SHA384
+	default "sha512" if MODULE_SIG_SHA512
+
+choice
+	prompt "Module compression mode"
+	help
+	  This option allows you to choose the algorithm which will be used to
+	  compress modules when 'make modules_install' is run. (or, you can
+	  choose to not compress modules at all.)
+
+	  External modules will also be compressed in the same way during the
+	  installation.
+
+	  For modules inside an initrd or initramfs, it's more efficient to
+	  compress the whole initrd or initramfs instead.
+
+	  This is fully compatible with signed modules.
+
+	  Please note that the tool used to load modules needs to support the
+	  corresponding algorithm. module-init-tools MAY support gzip, and kmod
+	  MAY support gzip, xz and zstd.
+
+	  Your build system needs to provide the appropriate compression tool
+	  to compress the modules.
+
+	  If in doubt, select 'None'.
+
+config MODULE_COMPRESS_NONE
+	bool "None"
+	help
+	  Do not compress modules. The installed modules are suffixed
+	  with .ko.
+
+config MODULE_COMPRESS_GZIP
+	bool "GZIP"
+	help
+	  Compress modules with GZIP. The installed modules are suffixed
+	  with .ko.gz.
+
+config MODULE_COMPRESS_XZ
+	bool "XZ"
+	help
+	  Compress modules with XZ. The installed modules are suffixed
+	  with .ko.xz.
+
+config MODULE_COMPRESS_ZSTD
+	bool "ZSTD"
+	help
+	  Compress modules with ZSTD. The installed modules are suffixed
+	  with .ko.zst.
+
+endchoice
+
+config MODULE_DECOMPRESS
+	bool "Support in-kernel module decompression"
+	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ
+	select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
+	select XZ_DEC if MODULE_COMPRESS_XZ
+	help
+
+	  Support for decompressing kernel modules by the kernel itself
+	  instead of relying on userspace to perform this task. Useful when
+	  load pinning security policy is enabled.
+
+	  If unsure, say N.
+
+config MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
+	bool "Allow loading of modules with missing namespace imports"
+	help
+	  Symbols exported with EXPORT_SYMBOL_NS*() are considered exported in
+	  a namespace. A module that makes use of a symbol exported with such a
+	  namespace is required to import the namespace via MODULE_IMPORT_NS().
+	  There is no technical reason to enforce correct namespace imports,
+	  but it creates consistency between symbols defining namespaces and
+	  users importing namespaces they make use of. This option relaxes this
+	  requirement and lifts the enforcement when loading a module.
+
+	  If unsure, say N.
+
+config MODPROBE_PATH
+	string "Path to modprobe binary"
+	default "/sbin/modprobe"
+	help
+	  When kernel code requests a module, it does so by calling
+	  the "modprobe" userspace utility. This option allows you to
+	  set the path where that binary is found. This can be changed
+	  at runtime via the sysctl file
+	  /proc/sys/kernel/modprobe. Setting this to the empty string
+	  removes the kernel's ability to request modules (but
+	  userspace can still load modules explicitly).
+
+config TRIM_UNUSED_KSYMS
+	bool "Trim unused exported kernel symbols" if EXPERT
+	depends on !COMPILE_TEST
+	help
+	  The kernel and some modules make many symbols available for
+	  other modules to use via EXPORT_SYMBOL() and variants. Depending
+	  on the set of modules being selected in your kernel configuration,
+	  many of those exported symbols might never be used.
+
+	  This option allows for unused exported symbols to be dropped from
+	  the build. In turn, this provides the compiler more opportunities
+	  (especially when using LTO) for optimizing the code and reducing
+	  binary size.  This might have some security advantages as well.
+
+	  If unsure, or if you need to build out-of-tree modules, say N.
+
+config UNUSED_KSYMS_WHITELIST
+	string "Whitelist of symbols to keep in ksymtab"
+	depends on TRIM_UNUSED_KSYMS
+	help
+	  By default, all unused exported symbols will be un-exported from the
+	  build when TRIM_UNUSED_KSYMS is selected.
+
+	  UNUSED_KSYMS_WHITELIST allows to whitelist symbols that must be kept
+	  exported at all times, even in absence of in-tree users. The value to
+	  set here is the path to a text file containing the list of symbols,
+	  one per line. The path can be absolute, or relative to the kernel
+	  source tree.
+
+config MODULES_TREE_LOOKUP
+	def_bool y
+	depends on PERF_EVENTS || TRACING || CFI_CLANG
+
+endif # MODULES
-- 
2.34.1

[PATCH v1 3/6] module: Make module_enable_x() independent of CONFIG_ARCH_HAS_STRICT_MODULE_RWX

[Christophe Leroy]

module_enable_x() has nothing to do with CONFIG_ARCH_HAS_STRICT_MODULE_RWX
allthough by coincidence architectures who need module_enable_x() are
selection CONFIG_ARCH_HAS_STRICT_MODULE_RWX.

Enable module_enable_x() for everyone everytime. If an architecture
already has module text set executable, it's a no-op.

Don't check text_size alignment. When CONFIG_STRICT_MODULE_RWX is set
the verification is already done in frob_rodata(). When
CONFIG_STRICT_MODULE_RWX is not set it is not a big deal to have the
start of data as executable. Just make sure we entirely get the last
page when the boundary is not aligned.

And don't BUG on misaligned base as some architectures like nios2
use kmalloc() for allocating modules. So just bail out in that case.
If that's a problem, a page fault will occur later anyway.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/internal.h |  6 ++----
 kernel/module/main.c     | 13 ++++++-------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 27ea99707059..ec4b46c67d10 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -27,9 +27,9 @@
 /*
  * Modules' sections will be aligned on page boundaries
  * to ensure complete separation of code and data, but
- * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y
+ * only when CONFIG_STRICT_MODULE_RWX=y
  */
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
+#ifdef CONFIG_STRICT_MODULE_RWX
 # define debug_align(X) PAGE_ALIGN(X)
 #else
 # define debug_align(X) (X)
@@ -182,10 +182,8 @@ static inline struct module *mod_find(unsigned long addr, struct mod_tree_root *
 }
 #endif /* CONFIG_MODULES_TREE_LOOKUP */
 
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
 void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start,
 								     int num_pages));
-#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
 
 #ifdef CONFIG_STRICT_MODULE_RWX
 void module_enable_ro(const struct module *mod, bool after_init);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index db503a212532..2b2f5d79bd7a 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1162,24 +1162,23 @@ resolve_symbol_wait(struct module *mod,
  * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
  * whether we are strict.
  */
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
 void frob_text(const struct module_layout *layout,
 	       int (*set_memory)(unsigned long start, int num_pages))
 {
-	BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1));
-	BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1));
 	set_memory((unsigned long)layout->base,
-		   layout->text_size >> PAGE_SHIFT);
+		   PAGE_ALIGN(layout->text_size) >> PAGE_SHIFT);
 }
 
 static void module_enable_x(const struct module *mod)
 {
+	if (!PAGE_ALIGNED(mod->core_layout.base))
+		return;
+	if (!PAGE_ALIGNED(mod->init_layout.base))
+		return;
+
 	frob_text(&mod->core_layout, set_memory_x);
 	frob_text(&mod->init_layout, set_memory_x);
 }
-#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
-static void module_enable_x(const struct module *mod) { }
-#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
 
 void __weak module_memfree(void *module_region)
 {
-- 
2.34.1

[PATCH v1 4/6] module: Move module_enable_x() and frob_text() in strict_rwx.c

[Christophe Leroy]

Move module_enable_x() together with module_enable_nx() and
module_enable_ro().

Those three functions are going together, they are all used
to set up the correct page flags on the different sections.

As module_enable_x() is used independently of
CONFIG_STRICT_MODULE_RWX, build strict_rwx.c all the time and
use IS_ENABLED(CONFIG_STRICT_MODULE_RWX) when relevant.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/Makefile     |  3 +--
 kernel/module/internal.h   | 15 +-----------
 kernel/module/main.c       | 38 ------------------------------
 kernel/module/strict_rwx.c | 48 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 50 insertions(+), 54 deletions(-)

diff --git a/kernel/module/Makefile b/kernel/module/Makefile
index 5fe90d246fcc..037ecc72ac23 100644
--- a/kernel/module/Makefile
+++ b/kernel/module/Makefile
@@ -7,12 +7,11 @@
 # and produce insane amounts of uninteresting coverage.
 KCOV_INSTRUMENT_main.o := n
 
-obj-y += main.o
+obj-y += main.o strict_rwx.o
 obj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o
 obj-$(CONFIG_MODULE_SIG) += signing.o
 obj-$(CONFIG_LIVEPATCH) += livepatch.o
 obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
-obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o
 obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_PROC_FS) += procfs.o
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index ec4b46c67d10..b80a746b2e5a 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -182,25 +182,12 @@ static inline struct module *mod_find(unsigned long addr, struct mod_tree_root *
 }
 #endif /* CONFIG_MODULES_TREE_LOOKUP */
 
-void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start,
-								     int num_pages));
-
-#ifdef CONFIG_STRICT_MODULE_RWX
 void module_enable_ro(const struct module *mod, bool after_init);
 void module_enable_nx(const struct module *mod);
+void module_enable_x(const struct module *mod);
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 				char *secstrings, struct module *mod);
 
-#else /* !CONFIG_STRICT_MODULE_RWX */
-static inline void module_enable_nx(const struct module *mod) { }
-static inline void module_enable_ro(const struct module *mod, bool after_init) {}
-static inline int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
-					      char *secstrings, struct module *mod)
-{
-	return 0;
-}
-#endif /* CONFIG_STRICT_MODULE_RWX */
-
 #ifdef CONFIG_MODULE_SIG
 int module_sig_check(struct load_info *info, int flags);
 #else /* !CONFIG_MODULE_SIG */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 2b2f5d79bd7a..47addf849ef7 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1142,44 +1142,6 @@ resolve_symbol_wait(struct module *mod,
 	return ksym;
 }
 
-/*
- * LKM RO/NX protection: protect module's text/ro-data
- * from modification and any data from execution.
- *
- * General layout of module is:
- *          [text] [read-only-data] [ro-after-init] [writable data]
- * text_size -----^                ^               ^               ^
- * ro_size ------------------------|               |               |
- * ro_after_init_size -----------------------------|               |
- * size -----------------------------------------------------------|
- *
- * These values are always page-aligned (as is base)
- */
-
-/*
- * Since some arches are moving towards PAGE_KERNEL module allocations instead
- * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
- * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
- * whether we are strict.
- */
-void frob_text(const struct module_layout *layout,
-	       int (*set_memory)(unsigned long start, int num_pages))
-{
-	set_memory((unsigned long)layout->base,
-		   PAGE_ALIGN(layout->text_size) >> PAGE_SHIFT);
-}
-
-static void module_enable_x(const struct module *mod)
-{
-	if (!PAGE_ALIGNED(mod->core_layout.base))
-		return;
-	if (!PAGE_ALIGNED(mod->init_layout.base))
-		return;
-
-	frob_text(&mod->core_layout, set_memory_x);
-	frob_text(&mod->init_layout, set_memory_x);
-}
-
 void __weak module_memfree(void *module_region)
 {
 	/*
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index a2104e9233a5..b023cea06af0 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -11,6 +11,34 @@
 #include <linux/set_memory.h>
 #include "internal.h"
 
+/*
+ * LKM RO/NX protection: protect module's text/ro-data
+ * from modification and any data from execution.
+ *
+ * General layout of module is:
+ *          [text] [read-only-data] [ro-after-init] [writable data]
+ * text_size -----^                ^               ^               ^
+ * ro_size ------------------------|               |               |
+ * ro_after_init_size -----------------------------|               |
+ * size -----------------------------------------------------------|
+ *
+ * These values are always page-aligned (as is base) when
+ * CONFIG_STRICT_MODULE_RWX is set.
+ */
+
+/*
+ * Since some arches are moving towards PAGE_KERNEL module allocations instead
+ * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() independent of
+ * CONFIG_STRICT_MODULE_RWX because they are needed regardless of whether we
+ * are strict.
+ */
+static void frob_text(const struct module_layout *layout,
+		      int (*set_memory)(unsigned long start, int num_pages))
+{
+	set_memory((unsigned long)layout->base,
+		   PAGE_ALIGN(layout->text_size) >> PAGE_SHIFT);
+}
+
 static void frob_rodata(const struct module_layout *layout,
 			int (*set_memory)(unsigned long start, int num_pages))
 {
@@ -41,10 +69,24 @@ static void frob_writable_data(const struct module_layout *layout,
 		   (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
 }
 
+void module_enable_x(const struct module *mod)
+{
+	if (!PAGE_ALIGNED(mod->core_layout.base) ||
+	    !PAGE_ALIGNED(mod->init_layout.base))
+		return;
+
+	frob_text(&mod->core_layout, set_memory_x);
+	frob_text(&mod->init_layout, set_memory_x);
+}
+
 void module_enable_ro(const struct module *mod, bool after_init)
 {
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return;
+#ifdef CONFIG_STRICT_MODULE_RWX
 	if (!rodata_enabled)
 		return;
+#endif
 
 	set_vm_flush_reset_perms(mod->core_layout.base);
 	set_vm_flush_reset_perms(mod->init_layout.base);
@@ -60,6 +102,9 @@ void module_enable_ro(const struct module *mod, bool after_init)
 
 void module_enable_nx(const struct module *mod)
 {
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return;
+
 	frob_rodata(&mod->data_layout, set_memory_nx);
 	frob_ro_after_init(&mod->data_layout, set_memory_nx);
 	frob_writable_data(&mod->data_layout, set_memory_nx);
@@ -73,6 +118,9 @@ int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 	const unsigned long shf_wx = SHF_WRITE | SHF_EXECINSTR;
 	int i;
 
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return 0;
+
 	for (i = 0; i < hdr->e_shnum; i++) {
 		if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) {
 			pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n",
-- 
2.34.1

[PATCH v1 5/6] module: Rework layout alignment to avoid BUG_ON()s

[Christophe Leroy]

Perform layout alignment verification up front and WARN_ON()
and fail module loading instead of crashing the machine.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/internal.h   |  1 +
 kernel/module/main.c       |  5 +++++
 kernel/module/strict_rwx.c | 28 +++++++++++++++++++---------
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index b80a746b2e5a..32add08e7895 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -187,6 +187,7 @@ void module_enable_nx(const struct module *mod);
 void module_enable_x(const struct module *mod);
 int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 				char *secstrings, struct module *mod);
+bool module_check_misalignment(const struct module *mod);
 
 #ifdef CONFIG_MODULE_SIG
 int module_sig_check(struct load_info *info, int flags);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 47addf849ef7..4876e2beb5b6 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2596,6 +2596,9 @@ static int complete_formation(struct module *mod, struct load_info *info)
 	/* This relies on module_mutex for list integrity. */
 	module_bug_finalize(info->hdr, info->sechdrs, mod);
 
+	if (module_check_misalignment(mod))
+		goto out_misaligned;
+
 	module_enable_ro(mod, false);
 	module_enable_nx(mod);
 	module_enable_x(mod);
@@ -2609,6 +2612,8 @@ static int complete_formation(struct module *mod, struct load_info *info)
 
 	return 0;
 
+out_misaligned:
+	err = -EINVAL;
 out:
 	mutex_unlock(&module_mutex);
 	return err;
diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
index b023cea06af0..3966198a4fc0 100644
--- a/kernel/module/strict_rwx.c
+++ b/kernel/module/strict_rwx.c
@@ -42,9 +42,6 @@ static void frob_text(const struct module_layout *layout,
 static void frob_rodata(const struct module_layout *layout,
 			int (*set_memory)(unsigned long start, int num_pages))
 {
-	BUG_ON(!PAGE_ALIGNED(layout->base));
-	BUG_ON(!PAGE_ALIGNED(layout->text_size));
-	BUG_ON(!PAGE_ALIGNED(layout->ro_size));
 	set_memory((unsigned long)layout->base + layout->text_size,
 		   (layout->ro_size - layout->text_size) >> PAGE_SHIFT);
 }
@@ -52,9 +49,6 @@ static void frob_rodata(const struct module_layout *layout,
 static void frob_ro_after_init(const struct module_layout *layout,
 			       int (*set_memory)(unsigned long start, int num_pages))
 {
-	BUG_ON(!PAGE_ALIGNED(layout->base));
-	BUG_ON(!PAGE_ALIGNED(layout->ro_size));
-	BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size));
 	set_memory((unsigned long)layout->base + layout->ro_size,
 		   (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT);
 }
@@ -62,13 +56,29 @@ static void frob_ro_after_init(const struct module_layout *layout,
 static void frob_writable_data(const struct module_layout *layout,
 			       int (*set_memory)(unsigned long start, int num_pages))
 {
-	BUG_ON(!PAGE_ALIGNED(layout->base));
-	BUG_ON(!PAGE_ALIGNED(layout->ro_after_init_size));
-	BUG_ON(!PAGE_ALIGNED(layout->size));
 	set_memory((unsigned long)layout->base + layout->ro_after_init_size,
 		   (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT);
 }
 
+static bool layout_check_misalignment(const struct module_layout *layout)
+{
+	return WARN_ON(!PAGE_ALIGNED(layout->base)) ||
+	       WARN_ON(!PAGE_ALIGNED(layout->text_size)) ||
+	       WARN_ON(!PAGE_ALIGNED(layout->ro_size)) ||
+	       WARN_ON(!PAGE_ALIGNED(layout->ro_after_init_size)) ||
+	       WARN_ON(!PAGE_ALIGNED(layout->size));
+}
+
+bool module_check_misalignment(const struct module *mod)
+{
+	if (!IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		return false;
+
+	return layout_check_misalignment(&mod->core_layout) ||
+	       layout_check_misalignment(&mod->data_layout) ||
+	       layout_check_misalignment(&mod->init_layout);
+}
+
 void module_enable_x(const struct module *mod)
 {
 	if (!PAGE_ALIGNED(mod->core_layout.base) ||
-- 
2.34.1

[PATCH v1 6/6] module: Rename debug_align() as strict_align()

[Christophe Leroy]

debug_align() was added by commit 84e1c6bb38eb ("x86: Add RO/NX
protection for loadable kernel modules")

At that time the config item was CONFIG_DEBUG_SET_MODULE_RONX.

But nowadays it has changed to CONFIG_STRICT_MODULE_RWX and
debug_align() is confusing because it has nothing to do with
DEBUG.

Rename it strict_align()

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/internal.h |  4 ++--
 kernel/module/kallsyms.c |  4 ++--
 kernel/module/main.c     | 14 +++++++-------
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 32add08e7895..c66f9da3e03d 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -30,9 +30,9 @@
  * only when CONFIG_STRICT_MODULE_RWX=y
  */
 #ifdef CONFIG_STRICT_MODULE_RWX
-# define debug_align(X) PAGE_ALIGN(X)
+# define strict_align(X) PAGE_ALIGN(X)
 #else
-# define debug_align(X) (X)
+# define strict_align(X) (X)
 #endif
 
 extern struct mutex module_mutex;
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index fe6723c040be..523a6ed8886b 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -139,7 +139,7 @@ void layout_symtab(struct module *mod, struct load_info *info)
 	mod->data_layout.size += strtab_size;
 	info->core_typeoffs = mod->data_layout.size;
 	mod->data_layout.size += ndst * sizeof(char);
-	mod->data_layout.size = debug_align(mod->data_layout.size);
+	mod->data_layout.size = strict_align(mod->data_layout.size);
 
 	/* Put string table section at end of init part of module. */
 	strsect->sh_flags |= SHF_ALLOC;
@@ -154,7 +154,7 @@ void layout_symtab(struct module *mod, struct load_info *info)
 	mod->init_layout.size += sizeof(struct mod_kallsyms);
 	info->init_typeoffs = mod->init_layout.size;
 	mod->init_layout.size += nsrc * sizeof(char);
-	mod->init_layout.size = debug_align(mod->init_layout.size);
+	mod->init_layout.size = strict_align(mod->init_layout.size);
 }
 
 /*
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 4876e2beb5b6..ce0ef17662c9 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1470,19 +1470,19 @@ static void layout_sections(struct module *mod, struct load_info *info)
 		}
 		switch (m) {
 		case 0: /* executable */
-			mod->core_layout.size = debug_align(mod->core_layout.size);
+			mod->core_layout.size = strict_align(mod->core_layout.size);
 			mod->core_layout.text_size = mod->core_layout.size;
 			break;
 		case 1: /* RO: text and ro-data */
-			mod->data_layout.size = debug_align(mod->data_layout.size);
+			mod->data_layout.size = strict_align(mod->data_layout.size);
 			mod->data_layout.ro_size = mod->data_layout.size;
 			break;
 		case 2: /* RO after init */
-			mod->data_layout.size = debug_align(mod->data_layout.size);
+			mod->data_layout.size = strict_align(mod->data_layout.size);
 			mod->data_layout.ro_after_init_size = mod->data_layout.size;
 			break;
 		case 4: /* whole core */
-			mod->data_layout.size = debug_align(mod->data_layout.size);
+			mod->data_layout.size = strict_align(mod->data_layout.size);
 			break;
 		}
 	}
@@ -1504,11 +1504,11 @@ static void layout_sections(struct module *mod, struct load_info *info)
 		}
 		switch (m) {
 		case 0: /* executable */
-			mod->init_layout.size = debug_align(mod->init_layout.size);
+			mod->init_layout.size = strict_align(mod->init_layout.size);
 			mod->init_layout.text_size = mod->init_layout.size;
 			break;
 		case 1: /* RO: text and ro-data */
-			mod->init_layout.size = debug_align(mod->init_layout.size);
+			mod->init_layout.size = strict_align(mod->init_layout.size);
 			mod->init_layout.ro_size = mod->init_layout.size;
 			break;
 		case 2:
@@ -1519,7 +1519,7 @@ static void layout_sections(struct module *mod, struct load_info *info)
 			mod->init_layout.ro_after_init_size = mod->init_layout.ro_size;
 			break;
 		case 4: /* whole init */
-			mod->init_layout.size = debug_align(mod->init_layout.size);
+			mod->init_layout.size = strict_align(mod->init_layout.size);
 			break;
 		}
 	}
-- 
2.34.1