linux-kernel - Re: [PATCH] module: Add log information for loading module failures

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Date: Tue, 18 Jun 2024 11:54:59 -0700
From: Luis Chamberlain <mcgrof@...nel.org>
To: Yusong Gao <a869920004@...il.com>
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: Add log information for loading module failures

On Fri, Jun 14, 2024 at 09:25:19AM +0000, Yusong Gao wrote:
> 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 <a869920004@...il.com>
> ---
>  kernel/module/signing.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/module/signing.c b/kernel/module/signing.c
> index a2ff4242e623..6a6493c8f7e4 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_notice("Loading module failed (errno=%d)\n", -err);
>  		return err;

I welcome pr_debug() messages but if we were to add a regular print for every
single type of failure we'd clutter the code, we don't want that.

  Luis