3.16.39-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
commit bca014caaa6130e57f69b5bf527967aa8ee70fdd upstream.
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@xxxxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
kernel/module.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2435,13 +2435,18 @@ static inline void kmemleak_load_module(
#endif
#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;
const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
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) {
/* We truncate the module to discard the signature */
info->len -= markerlen;
@@ -2463,7 +2468,7 @@ static int module_sig_check(struct load_
return err;
}
#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;
}
@@ -3200,7 +3205,7 @@ static int load_module(struct load_info
long err;
char *after_dashes;
- err = module_sig_check(info);
+ err = module_sig_check(info, flags);
if (err)
goto free_copy;
--
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