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Livepatching changes for 6.3
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This commit is contained in:
Linus Torvalds
commit
7dd86cf801
@ -129,22 +129,27 @@ int apply_relocate(Elf32_Shdr *sechdrs,
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return 0;
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}
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#else /*X86_64*/
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static int __apply_relocate_add(Elf64_Shdr *sechdrs,
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static int __write_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me,
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void *(*write)(void *dest, const void *src, size_t len))
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void *(*write)(void *dest, const void *src, size_t len),
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bool apply)
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{
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unsigned int i;
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Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
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Elf64_Sym *sym;
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void *loc;
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u64 val;
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u64 zero = 0ULL;
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DEBUGP("Applying relocate section %u to %u\n",
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DEBUGP("%s relocate section %u to %u\n",
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apply ? "Applying" : "Clearing",
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relsec, sechdrs[relsec].sh_info);
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for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
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size_t size;
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/* This is where to make the change */
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loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
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+ rel[i].r_offset;
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@ -162,56 +167,53 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs,
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switch (ELF64_R_TYPE(rel[i].r_info)) {
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case R_X86_64_NONE:
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break;
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continue; /* nothing to write */
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case R_X86_64_64:
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if (*(u64 *)loc != 0)
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goto invalid_relocation;
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write(loc, &val, 8);
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size = 8;
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break;
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case R_X86_64_32:
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if (*(u32 *)loc != 0)
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goto invalid_relocation;
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write(loc, &val, 4);
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if (val != *(u32 *)loc)
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if (val != *(u32 *)&val)
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goto overflow;
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size = 4;
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break;
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case R_X86_64_32S:
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if (*(s32 *)loc != 0)
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goto invalid_relocation;
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write(loc, &val, 4);
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if ((s64)val != *(s32 *)loc)
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if ((s64)val != *(s32 *)&val)
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goto overflow;
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size = 4;
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break;
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case R_X86_64_PC32:
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case R_X86_64_PLT32:
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if (*(u32 *)loc != 0)
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goto invalid_relocation;
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val -= (u64)loc;
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write(loc, &val, 4);
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#if 0
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if ((s64)val != *(s32 *)loc)
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goto overflow;
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#endif
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size = 4;
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break;
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case R_X86_64_PC64:
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if (*(u64 *)loc != 0)
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goto invalid_relocation;
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val -= (u64)loc;
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write(loc, &val, 8);
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size = 8;
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break;
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default:
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pr_err("%s: Unknown rela relocation: %llu\n",
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me->name, ELF64_R_TYPE(rel[i].r_info));
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return -ENOEXEC;
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}
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if (apply) {
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if (memcmp(loc, &zero, size)) {
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pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
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return -ENOEXEC;
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}
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write(loc, &val, size);
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} else {
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if (memcmp(loc, &val, size)) {
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pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
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return -ENOEXEC;
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}
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write(loc, &zero, size);
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}
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}
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return 0;
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invalid_relocation:
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pr_err("x86/modules: Skipping invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
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return -ENOEXEC;
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overflow:
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pr_err("overflow in relocation type %d val %Lx\n",
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(int)ELF64_R_TYPE(rel[i].r_info), val);
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@ -220,11 +222,12 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs,
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return -ENOEXEC;
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}
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int apply_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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static int write_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me,
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bool apply)
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{
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int ret;
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bool early = me->state == MODULE_STATE_UNFORMED;
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@ -235,8 +238,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
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mutex_lock(&text_mutex);
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}
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ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
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write);
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ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
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write, apply);
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if (!early) {
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text_poke_sync();
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@ -246,6 +249,26 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
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return ret;
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}
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int apply_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
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}
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#ifdef CONFIG_LIVEPATCH
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void clear_relocate_add(Elf64_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
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}
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#endif
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#endif
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int module_finalize(const Elf_Ehdr *hdr,
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@ -75,6 +75,23 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
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unsigned int symindex,
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unsigned int relsec,
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struct module *mod);
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#ifdef CONFIG_LIVEPATCH
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/*
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* Some architectures (namely x86_64 and ppc64) perform sanity checks when
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* applying relocations. If a patched module gets unloaded and then later
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* reloaded (and re-patched), klp re-applies relocations to the replacement
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* function(s). Any leftover relocations from the previous loading of the
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* patched module might trigger the sanity checks.
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*
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* To prevent that, when unloading a patched module, clear out any relocations
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* that might trigger arch-specific sanity checks on a future module reload.
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*/
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void clear_relocate_add(Elf_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me);
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#endif
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#else
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static inline int apply_relocate_add(Elf_Shdr *sechdrs,
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const char *strtab,
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@ -260,6 +260,14 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
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return 0;
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}
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void __weak clear_relocate_add(Elf_Shdr *sechdrs,
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const char *strtab,
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unsigned int symindex,
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unsigned int relsec,
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struct module *me)
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{
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}
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/*
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* At a high-level, there are two types of klp relocation sections: those which
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* reference symbols which live in vmlinux; and those which reference symbols
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@ -283,10 +291,10 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
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* the to-be-patched module to be loaded and patched sometime *after* the
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* klp module is loaded.
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*/
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int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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const char *shstrtab, const char *strtab,
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unsigned int symndx, unsigned int secndx,
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const char *objname)
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static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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const char *shstrtab, const char *strtab,
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unsigned int symndx, unsigned int secndx,
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const char *objname, bool apply)
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{
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int cnt, ret;
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char sec_objname[MODULE_NAME_LEN];
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@ -308,11 +316,26 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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if (strcmp(objname ? objname : "vmlinux", sec_objname))
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return 0;
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ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname);
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if (ret)
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return ret;
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if (apply) {
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ret = klp_resolve_symbols(sechdrs, strtab, symndx,
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sec, sec_objname);
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if (ret)
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return ret;
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return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
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return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
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}
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clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
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return 0;
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}
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int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
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const char *shstrtab, const char *strtab,
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unsigned int symndx, unsigned int secndx,
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const char *objname)
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{
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return klp_write_section_relocs(pmod, sechdrs, shstrtab, strtab, symndx,
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secndx, objname, true);
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}
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/*
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@ -761,8 +784,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
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func->old_sympos ? func->old_sympos : 1);
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}
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static int klp_apply_object_relocs(struct klp_patch *patch,
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struct klp_object *obj)
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static int klp_write_object_relocs(struct klp_patch *patch,
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struct klp_object *obj,
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bool apply)
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{
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int i, ret;
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struct klp_modinfo *info = patch->mod->klp_info;
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@ -773,10 +797,10 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
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if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
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continue;
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ret = klp_apply_section_relocs(patch->mod, info->sechdrs,
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ret = klp_write_section_relocs(patch->mod, info->sechdrs,
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info->secstrings,
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patch->mod->core_kallsyms.strtab,
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info->symndx, i, obj->name);
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info->symndx, i, obj->name, apply);
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if (ret)
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return ret;
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}
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@ -784,6 +808,18 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
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return 0;
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}
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static int klp_apply_object_relocs(struct klp_patch *patch,
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struct klp_object *obj)
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{
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return klp_write_object_relocs(patch, obj, true);
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}
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static void klp_clear_object_relocs(struct klp_patch *patch,
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struct klp_object *obj)
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{
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klp_write_object_relocs(patch, obj, false);
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}
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/* parts of the initialization that is done only when the object is loaded */
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static int klp_init_object_loaded(struct klp_patch *patch,
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struct klp_object *obj)
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@ -1171,7 +1207,7 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
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klp_unpatch_object(obj);
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klp_post_unpatch_callback(obj);
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klp_clear_object_relocs(patch, obj);
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klp_free_object_loaded(obj);
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break;
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}
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