Re: [PATCH v4 1/2] module: add elf_check_module_arch for module specific elf arch checks
flat view
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-06-15 02:33:30
Also in:
lkml
Subsystem:
module support, the rest · Maintainers:
Luis Chamberlain, Petr Pavlu, Daniel Gomez, Sami Tolvanen, Linus Torvalds
Excerpts from Jessica Yu's message of June 14, 2021 10:06 pm:
quoted hunk ↗ jump to hunk
+++ Nicholas Piggin [11/06/21 19:39 +1000]:quoted
The elf_check_arch() function is used to test usermode binaries, but kernel modules may have more specific requirements. powerpc would like to test for ABI version compatibility. Add an arch-overridable function elf_check_module_arch() that defaults to elf_check_arch() and use it in elf_validity_check(). Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> [np: split patch, added changelog] Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- include/linux/moduleloader.h | 5 +++++ kernel/module.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-)diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h index 9e09d11ffe5b..fdc042a84562 100644 --- a/include/linux/moduleloader.h +++ b/include/linux/moduleloader.h@@ -13,6 +13,11 @@ * must be implemented by each architecture. */ +// Allow arch to optionally do additional checking of module ELF header +#ifndef elf_check_module_arch +#define elf_check_module_arch elf_check_arch +#endifHi Nicholas, Why not make elf_check_module_arch() consistent with the other arch-specific functions? Please see module_frob_arch_sections(), module_{init,exit}_section(), etc in moduleloader.h. That is, they are all __weak functions that are overridable by arches. We can maybe make elf_check_module_arch() a weak symbol, available for arches to override if they want to perform additional elf checks. Then we don't have to have this one-off #define.
Like this? I like it. Good idea. Thanks, Nick
diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index 9e09d11ffe5b..7b4587a19189 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h@@ -13,6 +13,9 @@ * must be implemented by each architecture. */ +/* arch may override to do additional checking of ELF header architecture */ +bool module_elf_check_arch(Elf_Ehdr *hdr); + /* Adjust arch-specific sections. Return 0 on success. */ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
diff --git a/kernel/module.c b/kernel/module.c
index 7e78dfabca97..8b31c0b7c2a0 100644
--- a/kernel/module.c
+++ b/kernel/module.c@@ -3459,6 +3459,11 @@ static void flush_module_icache(const struct module *mod) (unsigned long)mod->core_layout.base + mod->core_layout.size); } +bool __weak module_elf_check_arch(Elf_Ehdr *hdr) +{ + return elf_check_arch(hdr); +} + int __weak module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, char *secstrings,