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module: Invalidate signatures on force-loaded modules

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Signing a module should only make it trusted by the specific kernel it
was built for, not anything else.  Loading a signed module meant for a
kernel with a different ABI could have interesting effects.
Therefore, treat all signatures as invalid when a module is
force-loaded.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Ben Hutchings 2016-04-28 09:24:01 +09:30 committed by Rusty Russell
parent 3205c36cf7
commit bca014caaa
1 changed files with 9 additions and 4 deletions
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13
kernel/module.c
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@ -2686,13 +2686,18 @@ static inline void kmemleak_load_module(const struct module *mod,
#endif #endif
#ifdef CONFIG_MODULE_SIG #ifdef CONFIG_MODULE_SIG
static int module_sig_check(struct load_info *info) static int module_sig_check(struct load_info *info, int flags)
{ {
int err = -ENOKEY; int err = -ENOKEY;
const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
const void *mod = info->hdr; const void *mod = info->hdr;
if (info->len > markerlen && /*
* Require flags == 0, as a module with version information
* removed is no longer the module that was signed
*/
if (flags == 0 &&
info->len > markerlen &&
memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
/* We truncate the module to discard the signature */ /* We truncate the module to discard the signature */
info->len -= markerlen; info->len -= markerlen;
@ -2711,7 +2716,7 @@ static int module_sig_check(struct load_info *info)
return err; return err;
} }
#else /* !CONFIG_MODULE_SIG */ #else /* !CONFIG_MODULE_SIG */
static int module_sig_check(struct load_info *info) static int module_sig_check(struct load_info *info, int flags)
{ {
return 0; return 0;
} }
@ -3506,7 +3511,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
long err; long err;
char *after_dashes; char *after_dashes;
err = module_sig_check(info); err = module_sig_check(info, flags);
if (err) if (err)
goto free_copy; goto free_copy;