Re: [PATCH v2 1/2] integrity: Refactor asymmetric_verify for reusability

Mimi Zohar
2026-04-15T02:00:36Z

On Wed, 2026-04-08 at 13:41 -0400, Stefan Berger wrote:
> Refactor asymmetric_verify for reusability. Have it call
> asymmetric_verify_common with the signature verification key and the
> public_key structure as parameters. sigv3 support for ML-DSA will need to
> check the public key type first to decide how to do the signature
> verification and therefore will have these parameters available for
> calling asymmetric_verify_common.
>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

Thanks, Stefan.

> ---
> security/integrity/digsig_asymmetric.c | 42 +++++++++++++++++---------
> 1 file changed, 28 insertions(+), 14 deletions(-)
>
> diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
> index 6e68ec3becbd..e29ed73f15cd 100644
> --- a/security/integrity/digsig_asymmetric.c
> +++ b/security/integrity/digsig_asymmetric.c
> @@ -79,18 +79,15 @@ static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
> return key;
> }
>
> -int asymmetric_verify(struct key *keyring, const char *sig,
> - int siglen, const char *data, int datalen)
> +static int asymmetric_verify_common(const struct key *key,
> + const struct public_key *pk,
> + const char *sig, int siglen,
> + const char *data, int datalen)
> {
> - struct public_key_signature pks;
> struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
> - const struct public_key *pk;
> - struct key *key;
> + struct public_key_signature pks;
> int ret;
>
> - if (siglen <= sizeof(*hdr))
> - return -EBADMSG;
> -
> siglen -= sizeof(*hdr);

Normally kernel-doc is unnecessary for static functions. Here, however, since
only the caller verifies the signature length, there should be a kernel-doc
function definition. It should indicate that all callers must verify the
signature length (siglen) and that the public key (pk) is not NULL, before
calling asymmetric_verify_common().

>
> if (siglen != be16_to_cpu(hdr->sig_size))
> @@ -99,15 +96,10 @@ int asymmetric_verify(struct key *keyring, const char *sig,
> if (hdr->hash_algo >= HASH_ALGO__LAST)
> return -ENOPKG;
>
> - key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
> - if (IS_ERR(key))
> - return PTR_ERR(key);
> -
> memset(&pks, 0, sizeof(pks));
>
> pks.hash_algo = hash_algo_name[hdr->hash_algo];
>
> - pk = asymmetric_key_public_key(key);
> pks.pkey_algo = pk->pkey_algo;
> if (!strcmp(pk->pkey_algo, "rsa")) {
> pks.encoding = "pkcs1";
> @@ -127,11 +119,33 @@ int asymmetric_verify(struct key *keyring, const char *sig,
> pks.s_size = siglen;
> ret = verify_signature(key, &pks);
> out:
> - key_put(key);

The kernel-doc function definition should also indicate that the caller must
free the key.

> pr_debug("%s() = %d\n", __func__, ret);
> return ret;
> }
>
> +int asymmetric_verify(struct key *keyring, const char *sig,
> + int siglen, const char *data, int datalen)
> +{
> + struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
> + const struct public_key *pk;
> + struct key *key;
> + int ret;
> +
> + if (siglen <= sizeof(*hdr))
> + return -EBADMSG;
> +
> + key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
> + if (IS_ERR(key))
> + return PTR_ERR(key);
> + pk = asymmetric_key_public_key(key);

Please add a test here making sure pk is not null.

thanks,

Mimi

> +
> + ret = asymmetric_verify_common(key, pk, sig, siglen, data, datalen);
> +
> + key_put(key);
> +
> + return ret;
> +}
> +
> /*
> * calc_file_id_hash - calculate the hash of the ima_file_id struct data
> * @type: xattr type [enum evm_ima_xattr_type]