diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/module.c | 93 |
1 files changed, 60 insertions, 33 deletions
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index 0a09d816794b..790fa9f4a342 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -128,22 +128,27 @@ int apply_relocate(Elf32_Shdr *sechdrs, return 0; } #else /*X86_64*/ -static int __apply_relocate_add(Elf64_Shdr *sechdrs, +static int __write_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me, - void *(*write)(void *dest, const void *src, size_t len)) + void *(*write)(void *dest, const void *src, size_t len), + bool apply) { unsigned int i; Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; Elf64_Sym *sym; void *loc; u64 val; + u64 zero = 0ULL; - DEBUGP("Applying relocate section %u to %u\n", + DEBUGP("%s relocate section %u to %u\n", + apply ? "Applying" : "Clearing", relsec, sechdrs[relsec].sh_info); for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { + size_t size; + /* This is where to make the change */ loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + rel[i].r_offset; @@ -161,52 +166,53 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs, switch (ELF64_R_TYPE(rel[i].r_info)) { case R_X86_64_NONE: - break; + continue; /* nothing to write */ case R_X86_64_64: - if (*(u64 *)loc != 0) - goto invalid_relocation; - write(loc, &val, 8); + size = 8; break; case R_X86_64_32: - if (*(u32 *)loc != 0) - goto invalid_relocation; - write(loc, &val, 4); - if (val != *(u32 *)loc) + if (val != *(u32 *)&val) goto overflow; + size = 4; break; case R_X86_64_32S: - if (*(s32 *)loc != 0) - goto invalid_relocation; - write(loc, &val, 4); - if ((s64)val != *(s32 *)loc) + if ((s64)val != *(s32 *)&val) goto overflow; + size = 4; break; case R_X86_64_PC32: case R_X86_64_PLT32: - if (*(u32 *)loc != 0) - goto invalid_relocation; val -= (u64)loc; - write(loc, &val, 4); + size = 4; break; case R_X86_64_PC64: - if (*(u64 *)loc != 0) - goto invalid_relocation; val -= (u64)loc; - write(loc, &val, 8); + size = 8; break; default: pr_err("%s: Unknown rela relocation: %llu\n", me->name, ELF64_R_TYPE(rel[i].r_info)); return -ENOEXEC; } + + if (apply) { + if (memcmp(loc, &zero, size)) { + pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n", + (int)ELF64_R_TYPE(rel[i].r_info), loc, val); + return -ENOEXEC; + } + write(loc, &val, size); + } else { + if (memcmp(loc, &val, size)) { + pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n", + (int)ELF64_R_TYPE(rel[i].r_info), loc, val); + return -ENOEXEC; + } + write(loc, &zero, size); + } } return 0; -invalid_relocation: - pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n", - (int)ELF64_R_TYPE(rel[i].r_info), loc, val); - return -ENOEXEC; - overflow: pr_err("overflow in relocation type %d val %Lx\n", (int)ELF64_R_TYPE(rel[i].r_info), val); @@ -215,11 +221,12 @@ overflow: return -ENOEXEC; } -int apply_relocate_add(Elf64_Shdr *sechdrs, - const char *strtab, - unsigned int symindex, - unsigned int relsec, - struct module *me) +static int write_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me, + bool apply) { int ret; bool early = me->state == MODULE_STATE_UNFORMED; @@ -230,8 +237,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, mutex_lock(&text_mutex); } - ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, - write); + ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me, + write, apply); if (!early) { text_poke_sync(); @@ -241,6 +248,26 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, return ret; } +int apply_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true); +} + +#ifdef CONFIG_LIVEPATCH +void clear_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + write_relocate_add(sechdrs, strtab, symindex, relsec, me, false); +} +#endif + #endif int module_finalize(const Elf_Ehdr *hdr, |