Commit 7dd86cf8 authored by Linus Torvalds's avatar Linus Torvalds

Merge tag 'livepatching-for-6.3' of...

Merge tag 'livepatching-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching

Pull livepatching updates from Petr Mladek:

 - Allow reloading a livepatched module by clearing livepatch-specific
   relocations in the livepatch module.

   Otherwise, the repeated load would fail on consistency checks.

* tag 'livepatching-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  livepatch,x86: Clear relocation targets on a module removal
  x86/module: remove unused code in __apply_relocate_add
parents d8763154 0c05e7bd
...@@ -129,22 +129,27 @@ int apply_relocate(Elf32_Shdr *sechdrs, ...@@ -129,22 +129,27 @@ int apply_relocate(Elf32_Shdr *sechdrs,
return 0; return 0;
} }
#else /*X86_64*/ #else /*X86_64*/
static int __apply_relocate_add(Elf64_Shdr *sechdrs, static int __write_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab, const char *strtab,
unsigned int symindex, unsigned int symindex,
unsigned int relsec, unsigned int relsec,
struct module *me, 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; unsigned int i;
Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
Elf64_Sym *sym; Elf64_Sym *sym;
void *loc; void *loc;
u64 val; 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); relsec, sechdrs[relsec].sh_info);
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
size_t size;
/* This is where to make the change */ /* This is where to make the change */
loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset; + rel[i].r_offset;
...@@ -162,56 +167,53 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs, ...@@ -162,56 +167,53 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs,
switch (ELF64_R_TYPE(rel[i].r_info)) { switch (ELF64_R_TYPE(rel[i].r_info)) {
case R_X86_64_NONE: case R_X86_64_NONE:
break; continue; /* nothing to write */
case R_X86_64_64: case R_X86_64_64:
if (*(u64 *)loc != 0) size = 8;
goto invalid_relocation;
write(loc, &val, 8);
break; break;
case R_X86_64_32: case R_X86_64_32:
if (*(u32 *)loc != 0) if (val != *(u32 *)&val)
goto invalid_relocation;
write(loc, &val, 4);
if (val != *(u32 *)loc)
goto overflow; goto overflow;
size = 4;
break; break;
case R_X86_64_32S: case R_X86_64_32S:
if (*(s32 *)loc != 0) if ((s64)val != *(s32 *)&val)
goto invalid_relocation;
write(loc, &val, 4);
if ((s64)val != *(s32 *)loc)
goto overflow; goto overflow;
size = 4;
break; break;
case R_X86_64_PC32: case R_X86_64_PC32:
case R_X86_64_PLT32: case R_X86_64_PLT32:
if (*(u32 *)loc != 0)
goto invalid_relocation;
val -= (u64)loc; val -= (u64)loc;
write(loc, &val, 4); size = 4;
#if 0
if ((s64)val != *(s32 *)loc)
goto overflow;
#endif
break; break;
case R_X86_64_PC64: case R_X86_64_PC64:
if (*(u64 *)loc != 0)
goto invalid_relocation;
val -= (u64)loc; val -= (u64)loc;
write(loc, &val, 8); size = 8;
break; break;
default: default:
pr_err("%s: Unknown rela relocation: %llu\n", pr_err("%s: Unknown rela relocation: %llu\n",
me->name, ELF64_R_TYPE(rel[i].r_info)); me->name, ELF64_R_TYPE(rel[i].r_info));
return -ENOEXEC; 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; 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: overflow:
pr_err("overflow in relocation type %d val %Lx\n", pr_err("overflow in relocation type %d val %Lx\n",
(int)ELF64_R_TYPE(rel[i].r_info), val); (int)ELF64_R_TYPE(rel[i].r_info), val);
...@@ -220,11 +222,12 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs, ...@@ -220,11 +222,12 @@ static int __apply_relocate_add(Elf64_Shdr *sechdrs,
return -ENOEXEC; return -ENOEXEC;
} }
int apply_relocate_add(Elf64_Shdr *sechdrs, static int write_relocate_add(Elf64_Shdr *sechdrs,
const char *strtab, const char *strtab,
unsigned int symindex, unsigned int symindex,
unsigned int relsec, unsigned int relsec,
struct module *me) struct module *me,
bool apply)
{ {
int ret; int ret;
bool early = me->state == MODULE_STATE_UNFORMED; bool early = me->state == MODULE_STATE_UNFORMED;
...@@ -235,8 +238,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, ...@@ -235,8 +238,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
mutex_lock(&text_mutex); mutex_lock(&text_mutex);
} }
ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
write); write, apply);
if (!early) { if (!early) {
text_poke_sync(); text_poke_sync();
...@@ -246,6 +249,26 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, ...@@ -246,6 +249,26 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
return ret; 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 #endif
int module_finalize(const Elf_Ehdr *hdr, int module_finalize(const Elf_Ehdr *hdr,
......
...@@ -75,6 +75,23 @@ int apply_relocate_add(Elf_Shdr *sechdrs, ...@@ -75,6 +75,23 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
unsigned int symindex, unsigned int symindex,
unsigned int relsec, unsigned int relsec,
struct module *mod); struct module *mod);
#ifdef CONFIG_LIVEPATCH
/*
* Some architectures (namely x86_64 and ppc64) perform sanity checks when
* applying relocations. If a patched module gets unloaded and then later
* reloaded (and re-patched), klp re-applies relocations to the replacement
* function(s). Any leftover relocations from the previous loading of the
* patched module might trigger the sanity checks.
*
* To prevent that, when unloading a patched module, clear out any relocations
* that might trigger arch-specific sanity checks on a future module reload.
*/
void clear_relocate_add(Elf_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me);
#endif
#else #else
static inline int apply_relocate_add(Elf_Shdr *sechdrs, static inline int apply_relocate_add(Elf_Shdr *sechdrs,
const char *strtab, const char *strtab,
......
...@@ -260,6 +260,14 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, ...@@ -260,6 +260,14 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
return 0; return 0;
} }
void __weak clear_relocate_add(Elf_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
}
/* /*
* At a high-level, there are two types of klp relocation sections: those which * At a high-level, there are two types of klp relocation sections: those which
* reference symbols which live in vmlinux; and those which reference symbols * reference symbols which live in vmlinux; and those which reference symbols
...@@ -283,10 +291,10 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, ...@@ -283,10 +291,10 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
* the to-be-patched module to be loaded and patched sometime *after* the * the to-be-patched module to be loaded and patched sometime *after* the
* klp module is loaded. * klp module is loaded.
*/ */
int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
const char *shstrtab, const char *strtab, const char *shstrtab, const char *strtab,
unsigned int symndx, unsigned int secndx, unsigned int symndx, unsigned int secndx,
const char *objname) const char *objname, bool apply)
{ {
int cnt, ret; int cnt, ret;
char sec_objname[MODULE_NAME_LEN]; char sec_objname[MODULE_NAME_LEN];
...@@ -308,11 +316,26 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, ...@@ -308,11 +316,26 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
if (strcmp(objname ? objname : "vmlinux", sec_objname)) if (strcmp(objname ? objname : "vmlinux", sec_objname))
return 0; return 0;
ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); if (apply) {
if (ret) ret = klp_resolve_symbols(sechdrs, strtab, symndx,
return ret; sec, sec_objname);
if (ret)
return ret;
return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
}
clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
return 0;
}
return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
const char *shstrtab, const char *strtab,
unsigned int symndx, unsigned int secndx,
const char *objname)
{
return klp_write_section_relocs(pmod, sechdrs, shstrtab, strtab, symndx,
secndx, objname, true);
} }
/* /*
...@@ -761,8 +784,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func) ...@@ -761,8 +784,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
func->old_sympos ? func->old_sympos : 1); func->old_sympos ? func->old_sympos : 1);
} }
static int klp_apply_object_relocs(struct klp_patch *patch, static int klp_write_object_relocs(struct klp_patch *patch,
struct klp_object *obj) struct klp_object *obj,
bool apply)
{ {
int i, ret; int i, ret;
struct klp_modinfo *info = patch->mod->klp_info; struct klp_modinfo *info = patch->mod->klp_info;
...@@ -773,10 +797,10 @@ static int klp_apply_object_relocs(struct klp_patch *patch, ...@@ -773,10 +797,10 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
continue; continue;
ret = klp_apply_section_relocs(patch->mod, info->sechdrs, ret = klp_write_section_relocs(patch->mod, info->sechdrs,
info->secstrings, info->secstrings,
patch->mod->core_kallsyms.strtab, patch->mod->core_kallsyms.strtab,
info->symndx, i, obj->name); info->symndx, i, obj->name, apply);
if (ret) if (ret)
return ret; return ret;
} }
...@@ -784,6 +808,18 @@ static int klp_apply_object_relocs(struct klp_patch *patch, ...@@ -784,6 +808,18 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
return 0; return 0;
} }
static int klp_apply_object_relocs(struct klp_patch *patch,
struct klp_object *obj)
{
return klp_write_object_relocs(patch, obj, true);
}
static void klp_clear_object_relocs(struct klp_patch *patch,
struct klp_object *obj)
{
klp_write_object_relocs(patch, obj, false);
}
/* parts of the initialization that is done only when the object is loaded */ /* parts of the initialization that is done only when the object is loaded */
static int klp_init_object_loaded(struct klp_patch *patch, static int klp_init_object_loaded(struct klp_patch *patch,
struct klp_object *obj) struct klp_object *obj)
...@@ -1171,7 +1207,7 @@ static void klp_cleanup_module_patches_limited(struct module *mod, ...@@ -1171,7 +1207,7 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
klp_unpatch_object(obj); klp_unpatch_object(obj);
klp_post_unpatch_callback(obj); klp_post_unpatch_callback(obj);
klp_clear_object_relocs(patch, obj);
klp_free_object_loaded(obj); klp_free_object_loaded(obj);
break; break;
} }
......
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