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Merge pull request #217 from jpoimboe/check-page-rw

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kmod/core: ensure page is RO before changing its permissions
This commit is contained in:
Seth Jennings 2014-05-27 23:23:26 -05:00
commit 52c0cd108d
1 changed files with 56 additions and 35 deletions
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91
kmod/core/core.c
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@ -457,15 +457,64 @@ static int kpatch_verify_symbol_match(char *name, unsigned long addr)
return 0;
}
static int kpatch_write_relocations(struct kpatch_module *kpmod)
{
int ret, i, size, readonly = 0;
struct kpatch_dynrela *dynrela;
u64 loc, val;
pte_t *pte;
unsigned int level;
for (i = 0; i < kpmod->dynrelas_nr; i++) {
dynrela = &kpmod->dynrelas[i];
ret = kpatch_verify_symbol_match(dynrela->name, dynrela->src);
if (ret)
return ret;
switch (dynrela->type) {
case R_X86_64_PC32:
loc = dynrela->dest;
val = (u32)(dynrela->src + dynrela->addend -
dynrela->dest);
size = 4;
break;
case R_X86_64_32S:
loc = dynrela->dest;
val = (s32)dynrela->src + dynrela->addend;
size = 4;
break;
default:
printk("unsupported rela type %ld for "
"0x%lx <- 0x%lx at index %d\n",
dynrela->type, dynrela->dest,
dynrela->src, i);
return -EINVAL;
}
pte = lookup_address(loc, &level);
if (!pte_write(*pte)) {
readonly = 1;
set_memory_rw(loc & PAGE_MASK, 1);
}
ret = probe_kernel_write((void *)loc, &val, size);
if (readonly)
set_memory_ro(loc & PAGE_MASK, 1);
if (ret)
return ret;
}
return 0;
}
int kpatch_register(struct kpatch_module *kpmod, bool replace)
{
int ret, i;
struct kpatch_func *funcs, *func;
int num_funcs = kpmod->patches_nr;
struct kpatch_dynrela *dynrela;
void *loc;
u64 val;
int size;
if (!kpmod->mod || !kpmod->patches || !num_funcs)
return -EINVAL;
@ -490,37 +539,9 @@ int kpatch_register(struct kpatch_module *kpmod, bool replace)
goto err_up;
}
for (i = 0; i < kpmod->dynrelas_nr; i++) {
dynrela = &kpmod->dynrelas[i];
ret = kpatch_verify_symbol_match(dynrela->name, dynrela->src);
if (ret)
goto err_put;
switch (dynrela->type) {
case R_X86_64_PC32:
loc = (void *)dynrela->dest;
val = (u32)(dynrela->src + dynrela->addend -
dynrela->dest);
size = 4;
break;
case R_X86_64_32S:
loc = (void *)dynrela->dest;
val = (s32)dynrela->src + dynrela->addend;
size = 4;
break;
default:
printk("unsupported rela type %ld for "
"0x%lx <- 0x%lx at index %d\n",
dynrela->type, dynrela->dest,
dynrela->src, i);
ret = -EINVAL;
goto err_put;
}
set_memory_rw((unsigned long)loc & PAGE_MASK, 1);
ret = probe_kernel_write(loc, &val, size);
set_memory_ro((unsigned long)loc & PAGE_MASK, 1);
if (ret)
goto err_put;
}
ret = kpatch_write_relocations(kpmod);
if (ret)
goto err_put;
for (i = 0; i < num_funcs; i++) {
func = &funcs[i];