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Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/module.c97
1 files changed, 60 insertions, 37 deletions
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 705fb2a41d7d..84ad0e61ba6e 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -129,22 +129,27 @@ 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;
@@ -162,56 +167,53 @@ 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);
-#if 0
- if ((s64)val != *(s32 *)loc)
- goto overflow;
-#endif
+ 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);
@@ -220,11 +222,12 @@ 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;
@@ -235,8 +238,8 @@ 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();
@@ -246,6 +249,26 @@ 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,