| Message ID | 20200901160016.3646-1-jeyu@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64/module: set trampoline section flags regardless of CONFIG_DYNAMIC_FTRACE | expand |
On Tue, 1 Sep 2020 at 19:00, Jessica Yu <jeyu@kernel.org> wrote: > > In the arm64 module linker script, the section .text.ftrace_trampoline > is specified unconditionally regardless of whether CONFIG_DYNAMIC_FTRACE > is enabled (this is simply due to the limitation that module linker > scripts are not preprocessed like the vmlinux one). > > Normally, for .plt and .text.ftrace_trampoline, the section flags > present in the module binary wouldn't matter since module_frob_arch_sections() > would assign them manually anyway. However, the arm64 module loader only > sets the section flags for .text.ftrace_trampoline when CONFIG_DYNAMIC_FTRACE=y. > That's only become problematic recently due to a recent change in > binutils-2.35, where the .text.ftrace_trampoline section (along with the > .plt section) is now marked writable and executable (WAX). > > We no longer allow writable and executable sections to be loaded due to > commit 5c3a7db0c7ec ("module: Harden STRICT_MODULE_RWX"), so this is > causing all modules linked with binutils-2.35 to be rejected under arm64. > Drop the IS_ENABLED(CONFIG_DYNAMIC_FTRACE) check in module_frob_arch_sections() > so that the section flags for .text.ftrace_trampoline get properly set to > SHF_EXECINSTR|SHF_ALLOC, without SHF_WRITE. > > Link: http://lore.kernel.org/r/20200831094651.GA16385@linux-8ccs > Acked-by: Will Deacon <will@kernel.org> > Signed-off-by: Jessica Yu <jeyu@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/kernel/module-plts.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c > index 0ce3a28e3347..2e224435c024 100644 > --- a/arch/arm64/kernel/module-plts.c > +++ b/arch/arm64/kernel/module-plts.c > @@ -305,8 +305,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, > mod->arch.core.plt_shndx = i; > else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) > mod->arch.init.plt_shndx = i; > - else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && > - !strcmp(secstrings + sechdrs[i].sh_name, > + else if (!strcmp(secstrings + sechdrs[i].sh_name, > ".text.ftrace_trampoline")) > tramp = sechdrs + i; > else if (sechdrs[i].sh_type == SHT_SYMTAB) > -- > 2.16.4 >
diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index 0ce3a28e3347..2e224435c024 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -305,8 +305,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, mod->arch.core.plt_shndx = i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) mod->arch.init.plt_shndx = i; - else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && - !strcmp(secstrings + sechdrs[i].sh_name, + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".text.ftrace_trampoline")) tramp = sechdrs + i; else if (sechdrs[i].sh_type == SHT_SYMTAB)
In the arm64 module linker script, the section .text.ftrace_trampoline is specified unconditionally regardless of whether CONFIG_DYNAMIC_FTRACE is enabled (this is simply due to the limitation that module linker scripts are not preprocessed like the vmlinux one). Normally, for .plt and .text.ftrace_trampoline, the section flags present in the module binary wouldn't matter since module_frob_arch_sections() would assign them manually anyway. However, the arm64 module loader only sets the section flags for .text.ftrace_trampoline when CONFIG_DYNAMIC_FTRACE=y. That's only become problematic recently due to a recent change in binutils-2.35, where the .text.ftrace_trampoline section (along with the .plt section) is now marked writable and executable (WAX). We no longer allow writable and executable sections to be loaded due to commit 5c3a7db0c7ec ("module: Harden STRICT_MODULE_RWX"), so this is causing all modules linked with binutils-2.35 to be rejected under arm64. Drop the IS_ENABLED(CONFIG_DYNAMIC_FTRACE) check in module_frob_arch_sections() so that the section flags for .text.ftrace_trampoline get properly set to SHF_EXECINSTR|SHF_ALLOC, without SHF_WRITE. Link: http://lore.kernel.org/r/20200831094651.GA16385@linux-8ccs Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Jessica Yu <jeyu@kernel.org> --- arch/arm64/kernel/module-plts.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)