[PATCH v13 06/12] crypto: Add supplementary info param to asymmetric key signature verification

David Howells
2026-01-20T14:51:50Z

Add a supplementary information parameter to the asymmetric key signature
verification API, in particular crypto_sig_verify() and sig_alg::verify.
This takes the form of a printable string containing of key=val elements.

This is needed as some algorithms require additional metadata
(e.g. RSASSA-PSS) and this extra metadata is included in the X.509
certificates and PKCS#7 messages. Furthermore, keyctl(KEYCTL_PKEY_VERIFY)
already allows for this to be passed to the kernel, as do the _SIGN,
_ENCRYPT and _DECRYPT keyctls.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Ignat Korchagin <ignat@cloudflare.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: "David S. Miller" <davem@davemloft.net>
cc: Lukas Wunner <lukas@wunner.de>
cc: keyrings@vger.kernel.org
cc: linux-crypto@vger.kernel.org
---
crypto/asymmetric_keys/asymmetric_type.c | 1 +
crypto/asymmetric_keys/public_key.c | 2 +-
crypto/asymmetric_keys/signature.c | 1 +
crypto/ecdsa-p1363.c | 5 +++--
crypto/ecdsa-x962.c | 5 +++--
crypto/ecdsa.c | 3 ++-
crypto/ecrdsa.c | 3 ++-
crypto/mldsa.c | 3 ++-
crypto/rsassa-pkcs1.c | 3 ++-
crypto/sig.c | 3 ++-
crypto/testmgr.c | 2 +-
crypto/testmgr.h | 1 +
include/crypto/public_key.h | 1 +
include/crypto/sig.h | 9 ++++++---
14 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index 348966ea2175..dad4f0edfa25 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -596,6 +596,7 @@ static int asymmetric_key_verify_signature(struct kernel_pkey_params *params,
.digest_size = params->in_len,
.encoding = params->encoding,
.hash_algo = params->hash_algo,
+ .info = params->info,
.digest = (void *)in,
.s = (void *)in2,
};
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index ed6b4b5ae4ef..61dc4f626620 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -433,7 +433,7 @@ int public_key_verify_signature(const struct public_key *pkey,
goto error_free_key;

ret = crypto_sig_verify(tfm, sig->s, sig->s_size,
- sig->digest, sig->digest_size);
+ sig->digest, sig->digest_size, sig->info);

error_free_key:
kfree_sensitive(key);
diff --git a/crypto/asymmetric_keys/signature.c b/crypto/asymmetric_keys/signature.c
index bea01cf27d0a..30ba50eb44af 100644
--- a/crypto/asymmetric_keys/signature.c
+++ b/crypto/asymmetric_keys/signature.c
@@ -30,6 +30,7 @@ void public_key_signature_free(struct public_key_signature *sig)
kfree(sig->s);
if (sig->digest_free)
kfree(sig->digest);
+ kfree(sig->info);
kfree(sig);
}
}
diff --git a/crypto/ecdsa-p1363.c b/crypto/ecdsa-p1363.c
index e0c55c64711c..fa987dba1213 100644
--- a/crypto/ecdsa-p1363.c
+++ b/crypto/ecdsa-p1363.c
@@ -18,7 +18,8 @@ struct ecdsa_p1363_ctx {

static int ecdsa_p1363_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct ecdsa_p1363_ctx *ctx = crypto_sig_ctx(tfm);
unsigned int keylen = DIV_ROUND_UP_POW2(crypto_sig_keysize(ctx->child),
@@ -32,7 +33,7 @@ static int ecdsa_p1363_verify(struct crypto_sig *tfm,
ecc_digits_from_bytes(src, keylen, sig.r, ndigits);
ecc_digits_from_bytes(src + keylen, keylen, sig.s, ndigits);

- return crypto_sig_verify(ctx->child, &sig, sizeof(sig), digest, dlen);
+ return crypto_sig_verify(ctx->child, &sig, sizeof(sig), digest, dlen, info);
}

static unsigned int ecdsa_p1363_key_size(struct crypto_sig *tfm)
diff --git a/crypto/ecdsa-x962.c b/crypto/ecdsa-x962.c
index ee71594d10a0..5d7f1078989c 100644
--- a/crypto/ecdsa-x962.c
+++ b/crypto/ecdsa-x962.c
@@ -75,7 +75,8 @@ int ecdsa_get_signature_s(void *context, size_t hdrlen, unsigned char tag,

static int ecdsa_x962_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct ecdsa_x962_ctx *ctx = crypto_sig_ctx(tfm);
struct ecdsa_x962_signature_ctx sig_ctx;
@@ -89,7 +90,7 @@ static int ecdsa_x962_verify(struct crypto_sig *tfm,
return err;

return crypto_sig_verify(ctx->child, &sig_ctx.sig, sizeof(sig_ctx.sig),
- digest, dlen);
+ digest, dlen, info);
}

static unsigned int ecdsa_x962_key_size(struct crypto_sig *tfm)
diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c
index ce8e4364842f..144fd6b9168b 100644
--- a/crypto/ecdsa.c
+++ b/crypto/ecdsa.c
@@ -65,7 +65,8 @@ static int _ecdsa_verify(struct ecc_ctx *ctx, const u64 *hash, const u64 *r, con
*/
static int ecdsa_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct ecc_ctx *ctx = crypto_sig_ctx(tfm);
size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
diff --git a/crypto/ecrdsa.c b/crypto/ecrdsa.c
index 2c0602f0cd40..59f2d5bb3be4 100644
--- a/crypto/ecrdsa.c
+++ b/crypto/ecrdsa.c
@@ -69,7 +69,8 @@ static const struct ecc_curve *get_curve_by_oid(enum OID oid)

static int ecrdsa_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct ecrdsa_ctx *ctx = crypto_sig_ctx(tfm);
unsigned int ndigits = dlen / sizeof(u64);
diff --git a/crypto/mldsa.c b/crypto/mldsa.c
index 2146c774b5ca..ba071d030ab0 100644
--- a/crypto/mldsa.c
+++ b/crypto/mldsa.c
@@ -25,7 +25,8 @@ static int crypto_mldsa_sign(struct crypto_sig *tfm,

static int crypto_mldsa_verify(struct crypto_sig *tfm,
const void *sig, unsigned int sig_len,
- const void *msg, unsigned int msg_len)
+ const void *msg, unsigned int msg_len,
+ const char *info)
{
const struct crypto_mldsa_ctx *ctx = crypto_sig_ctx(tfm);

diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c
index 94fa5e9600e7..6283050e609a 100644
--- a/crypto/rsassa-pkcs1.c
+++ b/crypto/rsassa-pkcs1.c
@@ -215,7 +215,8 @@ static int rsassa_pkcs1_sign(struct crypto_sig *tfm,

static int rsassa_pkcs1_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct sig_instance *inst = sig_alg_instance(tfm);
struct rsassa_pkcs1_inst_ctx *ictx = sig_instance_ctx(inst);
diff --git a/crypto/sig.c b/crypto/sig.c
index beba745b6405..c56fea3a53ae 100644
--- a/crypto/sig.c
+++ b/crypto/sig.c
@@ -92,7 +92,8 @@ static int sig_default_sign(struct crypto_sig *tfm,

static int sig_default_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *dst, unsigned int dlen)
+ const void *dst, unsigned int dlen,
+ const char *info)
{
return -ENOSYS;
}
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 5df204d9c9dd..51f76b15f134 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -3969,7 +3969,7 @@ static int test_sig_one(struct crypto_sig *tfm, const struct sig_testvec *vecs)
* (which does not require a private key)
*/
err = crypto_sig_verify(tfm, vecs->c, vecs->c_size,
- vecs->m, vecs->m_size);
+ vecs->m, vecs->m_size, vecs->verify_info);
if (err) {
pr_err("alg: sig: verify test failed: err %d\n", err);
return err;
diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index 1a3329e1c325..305adad2f2d0 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -146,6 +146,7 @@ struct akcipher_testvec {

struct sig_testvec {
const unsigned char *key;
+ const unsigned char *verify_info;
const unsigned char *params;
const unsigned char *m;
const unsigned char *c;
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 68899a49cd0d..b6f2f2218aae 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -48,6 +48,7 @@ struct public_key_signature {
u32 digest_size; /* Number of bytes in digest */
bool digest_free; /* T if digest needs freeing */
bool algo_does_hash; /* Public key algo does its own hashing */
+ char *info; /* Supplementary parameters */
const char *pkey_algo;
const char *hash_algo;
const char *encoding;
diff --git a/include/crypto/sig.h b/include/crypto/sig.h
index fa6dafafab3f..885fa6487780 100644
--- a/include/crypto/sig.h
+++ b/include/crypto/sig.h
@@ -56,7 +56,8 @@ struct sig_alg {
void *dst, unsigned int dlen);
int (*verify)(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen);
+ const void *digest, unsigned int dlen,
+ const char *info);
int (*set_pub_key)(struct crypto_sig *tfm,
const void *key, unsigned int keylen);
int (*set_priv_key)(struct crypto_sig *tfm,
@@ -209,16 +210,18 @@ static inline int crypto_sig_sign(struct crypto_sig *tfm,
* @slen: source length
* @digest: digest
* @dlen: digest length
+ * @info: Additional parameters as a set of k=v
*
* Return: zero on verification success; error code in case of error.
*/
static inline int crypto_sig_verify(struct crypto_sig *tfm,
const void *src, unsigned int slen,
- const void *digest, unsigned int dlen)
+ const void *digest, unsigned int dlen,
+ const char *info)
{
struct sig_alg *alg = crypto_sig_alg(tfm);

- return alg->verify(tfm, src, slen, digest, dlen);
+ return alg->verify(tfm, src, slen, digest, dlen, info);
}

/**