[PATCH v2] module: Add log information for loading module failures

[Yusong Gao]

Add log information in kernel-space when loading module failures.
Try to load the unsigned module and the module with bad signature
when set 1 to /sys/module/module/parameters/sig_enforce.

Unsigned module case:
(linux) insmod unsigned.ko
[   18.714661] Loading of unsigned module is rejected
insmod: can't insert 'unsigned.ko': Key was rejected by service
(linux)

Bad signature module case:
(linux) insmod bad_signature.ko
insmod: can't insert 'bad_signature.ko': Key was rejected by service
(linux)

There have different logging behavior the bad signature case only log
in user-space, add log info for fatal errors in module_sig_check().

Signed-off-by: Yusong Gao <a869920...@gmail.com>
---
V2: Change print level from notice to debug.
---
 kernel/module/signing.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/module/signing.c b/kernel/module/signing.c
index a2ff4242e623..b0c7b30e4d89 100644
--- a/kernel/module/signing.c
+++ b/kernel/module/signing.c
@@ -113,6 +113,7 @@ int module_sig_check(struct load_info *info, int flags)
                 * unparseable signatures, and signature check failures --
                 * even if signatures aren't required.
                 */
+               pr_debug("Loading module failed (errno=%d)\n", -err);
                return err;
        }
 
-- 
2.34.1