linux-kernel - Re: [PATCH v4 13/17] module: Report signature type to users

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Message-ID: <fd19f9d3-b01c-4cc8-9fd5-642350e7b36b@suse.com>
Date: Thu, 29 Jan 2026 15:44:31 +0100
From: Petr Pavlu <petr.pavlu@...e.com>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Nathan Chancellor <nathan@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 Luis Chamberlain <mcgrof@...nel.org>, Sami Tolvanen
 <samitolvanen@...gle.com>, Daniel Gomez <da.gomez@...sung.com>,
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 Roberto Sassu <roberto.sassu@...wei.com>,
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Subject: Re: [PATCH v4 13/17] module: Report signature type to users

On 1/13/26 1:28 PM, Thomas Weißschuh wrote:
> The upcoming CONFIG_MODULE_HASHES will introduce a signature type.
> This needs to be handled by callers differently than PKCS7 signatures.
> 
> Report the signature type to the caller and let them verify it.
> 
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
> [...]
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index d65bc300a78c..2a28a0ece809 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3348,19 +3348,24 @@ static int module_integrity_check(struct load_info *info, int flags)
>  {
>  	bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
>  				       MODULE_INIT_IGNORE_VERMAGIC);
> +	enum pkey_id_type sig_type;
>  	size_t sig_len;
>  	const u8 *sig;
>  	int err = 0;
>  
>  	if (IS_ENABLED(CONFIG_MODULE_SIG_POLICY)) {
>  		err = mod_split_sig(info->hdr, &info->len, mangled_module,
> -				    &sig_len, &sig, "module");
> +				    &sig_type, &sig_len, &sig, "module");
>  		if (err)
>  			return err;
>  	}
>  
> -	if (IS_ENABLED(CONFIG_MODULE_SIG))
> +	if (IS_ENABLED(CONFIG_MODULE_SIG) && sig_type == PKEY_ID_PKCS7) {
>  		err = module_sig_check(info, sig, sig_len);
> +	} else {
> +		pr_err("module: not signed with expected PKCS#7 message\n");
> +		err = -ENOPKG;
> +	}

The new else branch means that if the user chooses not to configure any
module integrity policy, they will no longer be able to load any
modules. I think this entire if-else part should be moved under the
IS_ENABLED(CONFIG_MODULE_SIG_POLICY) block above, as I'm mentioning on
patch #12.

-- 
Thanks,
Petr