From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com,
jbaron@akamai.com, torvalds@linux-foundation.org,
tglx@linutronix.de, mingo@kernel.org, namit@vmware.com,
hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org,
jeyu@kernel.org
Subject: Re: [PATCH v4 15/16] module: Move where we mark modules RO,X
Date: Thu, 24 Oct 2019 12:59:04 +0200 [thread overview]
Message-ID: <20191024105904.GB4131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191023171514.7hkhtvfcj5vluwcg@treble>
On Wed, Oct 23, 2019 at 12:15:14PM -0500, Josh Poimboeuf wrote:
> On Wed, Oct 23, 2019 at 05:16:54PM +0200, Peter Zijlstra wrote:
> > @@ -157,6 +158,14 @@ static int __apply_relocate_add(Elf64_Sh
> >
> > val = sym->st_value + rel[i].r_addend;
> >
> > + /*
> > + * .klp.rela.* sections should only contain module
> > + * related RELAs. All core-kernel RELAs should be in
> > + * normal .rela.* sections and be applied when loading
> > + * the patch module itself.
> > + */
> > + WARN_ON_ONCE(klp && core_kernel_text(val));
> > +
>
> This isn't quite true, we also use .klp.rela sections to access
> unexported vmlinux symbols.
Yes, you said in that earlier email. That all makes it really hard to
validate this. But unless we validate it, it will stay buggy :/
Hmmm.... /me ponders
The alternative would be to apply the .klp.rela.* sections twice, once
at patch-module load time and then apply those core_kernel_text()
entries, and then once later and skip over them.
How's this?
---
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -126,12 +126,20 @@ int apply_relocate(Elf32_Shdr *sechdrs,
return 0;
}
#else /*X86_64*/
+
+enum rela_filter {
+ rela_all = 0,
+ rela_core,
+ rela_mod,
+};
+
static int __apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me,
- void *(*write)(void *addr, const void *val, size_t size))
+ void *(*write)(void *addr, const void *val, size_t size),
+ enum rela_filter filter)
{
unsigned int i;
Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
@@ -157,6 +165,11 @@ static int __apply_relocate_add(Elf64_Sh
val = sym->st_value + rel[i].r_addend;
+ if (filter) {
+ if ((filter == rela_core) != !!core_kernel_text(val))
+ continue;
+ }
+
switch (ELF64_R_TYPE(rel[i].r_info)) {
case R_X86_64_NONE:
break;
@@ -223,18 +236,21 @@ int apply_relocate_add(Elf64_Shdr *sechd
unsigned int relsec,
struct module *me)
{
- return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, memcpy);
+ return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, memcpy, rela_all);
}
int klp_apply_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
- struct module *me)
+ struct module *me, bool late)
{
int ret;
- ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, text_poke);
+ if (!late)
+ return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, memcpy, rela_core);
+
+ ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, text_poke, rela_mod);
if (!ret)
text_poke_sync();
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -222,7 +222,7 @@ extern int klp_apply_relocate_add(Elf64_
const char *strtab,
unsigned int symindex,
unsigned int relsec,
- struct module *me);
+ struct module *me, bool late);
#else /* !CONFIG_LIVEPATCH */
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -245,15 +245,6 @@ static int klp_resolve_symbols(Elf_Shdr
return 0;
}
-int __weak klp_apply_relocate_add(Elf64_Shdr *sechdrs,
- const char *strtab,
- unsigned int symindex,
- unsigned int relsec,
- struct module *me)
-{
- return apply_relocate_add(sechdrs, strtab, symindex, relsec, me);
-}
-
static int klp_write_object_relocations(struct module *pmod,
struct klp_object *obj)
{
@@ -296,7 +287,7 @@ static int klp_write_object_relocations(
ret = klp_apply_relocate_add(pmod->klp_info->sechdrs,
pmod->core_kallsyms.strtab,
- pmod->klp_info->symndx, i, pmod);
+ pmod->klp_info->symndx, i, pmod, true);
if (ret)
break;
}
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2328,8 +2328,13 @@ static int apply_relocations(struct modu
continue;
/* Livepatch relocation sections are applied by livepatch */
- if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH)
+ if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) {
+ if (info->sechdrs[i].sh_type == SHT_RELA) {
+ klp_apply_relocate_add(info->sechdrs, info->strtab,
+ info->index.sym, i, mod, false);
+ }
continue;
+ }
if (info->sechdrs[i].sh_type == SHT_REL)
err = apply_relocate(info->sechdrs, info->strtab,
next prev parent reply other threads:[~2019-10-24 10:59 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 7:35 [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 01/16] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 02/16] x86/alternatives: Update int3_emulate_push() comment Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 03/16] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-10-21 8:48 ` Ingo Molnar
2019-10-21 9:21 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 04/16] x86/alternatives: Add and use text_gen_insn() helper Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 05/16] x86/ftrace: Use text_poke() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 06/16] x86/mm: Remove set_kernel_text_r[ow]() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 07/16] x86/alternative: Add text_opcode_size() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 08/16] x86/ftrace: Use text_gen_insn() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 09/16] x86/alternative: Remove text_poke_loc::len Peter Zijlstra
2019-10-21 8:58 ` Ingo Molnar
2019-10-21 9:02 ` Ingo Molnar
2019-10-18 7:35 ` [PATCH v4 10/16] x86/alternative: Shrink text_poke_loc Peter Zijlstra
2019-10-21 9:01 ` Ingo Molnar
2019-10-21 9:25 ` Peter Zijlstra
2019-10-21 9:33 ` Ingo Molnar
2019-10-18 7:35 ` [PATCH v4 11/16] x86/kprobes: Convert to text-patching.h Peter Zijlstra
2019-10-21 14:57 ` Masami Hiramatsu
2019-10-18 7:35 ` [PATCH v4 12/16] x86/kprobes: Fix ordering Peter Zijlstra
2019-10-22 1:35 ` Masami Hiramatsu
2019-10-22 10:31 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 13/16] arm/ftrace: Use __patch_text_real() Peter Zijlstra
2019-10-28 16:25 ` Will Deacon
2019-10-28 16:34 ` Peter Zijlstra
2019-10-28 16:35 ` Peter Zijlstra
2019-10-28 16:47 ` Will Deacon
2019-10-28 16:55 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 14/16] module: Remove set_all_modules_text_*() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 15/16] module: Move where we mark modules RO,X Peter Zijlstra
2019-10-21 13:53 ` Josh Poimboeuf
2019-10-21 14:14 ` Peter Zijlstra
2019-10-21 15:34 ` Peter Zijlstra
2019-10-21 15:44 ` Peter Zijlstra
2019-10-21 16:11 ` Peter Zijlstra
2019-10-22 11:31 ` Heiko Carstens
2019-10-22 12:31 ` Peter Zijlstra
2019-10-23 11:48 ` Peter Zijlstra
2019-10-23 15:16 ` Peter Zijlstra
2019-10-23 17:15 ` Josh Poimboeuf
2019-10-24 10:59 ` Peter Zijlstra [this message]
2019-10-24 18:31 ` Josh Poimboeuf
2019-10-24 20:33 ` Peter Zijlstra
2019-10-23 17:00 ` Josh Poimboeuf
2019-10-24 13:16 ` Peter Zijlstra
2019-10-25 6:44 ` Petr Mladek
2019-10-25 8:43 ` Peter Zijlstra
2019-10-25 10:06 ` Peter Zijlstra
2019-10-25 13:50 ` Josh Poimboeuf
2019-10-26 1:17 ` Josh Poimboeuf
2019-10-28 10:07 ` Peter Zijlstra
2019-10-28 10:43 ` Peter Zijlstra
2019-10-25 9:16 ` Peter Zijlstra
2019-10-22 2:21 ` Steven Rostedt
2019-10-22 20:24 ` Peter Zijlstra
2019-10-22 20:40 ` Steven Rostedt
2019-10-23 9:07 ` Peter Zijlstra
2019-10-23 18:52 ` Steven Rostedt
2019-10-24 10:16 ` Peter Zijlstra
2019-10-24 10:18 ` Peter Zijlstra
2019-10-24 15:00 ` Steven Rostedt
2019-10-24 16:43 ` Peter Zijlstra
2019-10-24 18:17 ` Steven Rostedt
2019-10-24 20:24 ` Peter Zijlstra
2019-10-24 20:28 ` Steven Rostedt
2019-10-18 7:35 ` [PATCH v4 16/16] ftrace: Merge ftrace_module_{init,enable}() Peter Zijlstra
2019-10-18 8:20 ` Peter Zijlstra
2019-10-21 9:09 ` [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Ingo Molnar
2019-10-21 13:38 ` Steven Rostedt
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