linux-kernel - Re: [PATCH v5 3/6] kexec_file: Don't opencode appended signature verification.

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Date:   Tue, 25 Jan 2022 12:15:56 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Michal Suchanek <msuchanek@...e.de>,
        David Howells <dhowells@...hat.com>
Cc:     keyrings@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-integrity@...r.kernel.org, kexec@...ts.infradead.org,
        Philipp Rudo <prudo@...hat.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Nayna <nayna@...ux.vnet.ibm.com>, Rob Herring <robh@...nel.org>,
        linux-s390@...r.kernel.org, Vasily Gorbik <gor@...ux.ibm.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Jessica Yu <jeyu@...nel.org>, linux-kernel@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org,
        Frank van der Linden <fllinden@...zon.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Daniel Axtens <dja@...ens.net>, buendgen@...ibm.com,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Baoquan He <bhe@...hat.com>,
        linux-security-module@...r.kernel.org
Subject: Re: [PATCH v5 3/6] kexec_file: Don't opencode appended signature
 verification.

On Tue, Jan 11, 2022 at 12:37:45PM +0100, Michal Suchanek wrote:
> diff --git a/include/linux/verification.h b/include/linux/verification.h
> index a655923335ae..32db9287a7b0 100644
> --- a/include/linux/verification.h
> +++ b/include/linux/verification.h
> @@ -60,5 +60,8 @@ extern int verify_pefile_signature(const void *pebuf, unsigned pelen,
>  				   enum key_being_used_for usage);
>  #endif
>  
> +int verify_appended_signature(const void *data, unsigned long *len,
> +			      struct key *trusted_keys, const char *what);
> +

Looks very non-module specific.

> diff --git a/kernel/module_signing.c b/kernel/module_signing.c
> index 8723ae70ea1f..30149969f21f 100644
> --- a/kernel/module_signing.c
> +++ b/kernel/module_signing.c
> @@ -14,32 +14,38 @@
>  #include <crypto/public_key.h>
>  #include "module-internal.h"
>  
> -/*
> - * Verify the signature on a module.
> +/**
> + * verify_appended_signature - Verify the signature on a module with the
> + * signature marker stripped.
> + * @data: The data to be verified
> + * @len: Size of @data.
> + * @trusted_keys: Keyring to use for verification
> + * @what: Informational string for log messages
>   */
> -int mod_verify_sig(const void *mod, struct load_info *info)
> +int verify_appended_signature(const void *data, unsigned long *len,
> +			      struct key *trusted_keys, const char *what)
>  {
> -	struct module_signature ms;
> -	size_t sig_len, modlen = info->len;
> +	struct module_signature *ms;

There goes the abstraction, so why not make this clear where we re-use
the struct module_signature for various things and call it as it is,
verify_mod_appended_signature() or some such?

David? Any preference?

Other than that:

Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>

  Luis