[PATCH v12 07/10] x509: Add support for parsing x509 certs with ECDSA keys

Stefan Berger
2021-03-16T21:08:55Z

Add support for parsing of x509 certificates that contain ECDSA keys,
such as NIST P256, that have been signed by a CA using any of the
current SHA hash algorithms.

Cc: David Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

---

v7->v8:
- do not detect key algo using parse_OID() in public_key.c but set
pkey_algo to the key type 'ecdsa-nist-p192/256' when parsing cert
---
crypto/asymmetric_keys/public_key.c | 4 ++-
crypto/asymmetric_keys/x509_cert_parser.c | 34 ++++++++++++++++++++++-
crypto/asymmetric_keys/x509_public_key.c | 4 ++-
include/linux/oid_registry.h | 2 ++
4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 788a4ba1e2e7..4fefb219bfdc 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/scatterlist.h>
+#include <linux/asn1.h>
#include <keys/asymmetric-subtype.h>
#include <crypto/public_key.h>
#include <crypto/akcipher.h>
@@ -85,7 +86,8 @@ int software_key_determine_akcipher(const char *encoding,
return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
}

- if (strcmp(encoding, "raw") == 0) {
+ if (strcmp(encoding, "raw") == 0 ||
+ strcmp(encoding, "x962") == 0) {
strcpy(alg_name, pkey->pkey_algo);
return 0;
}
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 1621ceaf5c95..f5d547c6dfb5 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -227,6 +227,26 @@ int x509_note_pkey_algo(void *context, size_t hdrlen,
ctx->cert->sig->hash_algo = "sha224";
goto rsa_pkcs1;

+ case OID_id_ecdsa_with_sha1:
+ ctx->cert->sig->hash_algo = "sha1";
+ goto ecdsa;
+
+ case OID_id_ecdsa_with_sha224:
+ ctx->cert->sig->hash_algo = "sha224";
+ goto ecdsa;
+
+ case OID_id_ecdsa_with_sha256:
+ ctx->cert->sig->hash_algo = "sha256";
+ goto ecdsa;
+
+ case OID_id_ecdsa_with_sha384:
+ ctx->cert->sig->hash_algo = "sha384";
+ goto ecdsa;
+
+ case OID_id_ecdsa_with_sha512:
+ ctx->cert->sig->hash_algo = "sha512";
+ goto ecdsa;
+
case OID_gost2012Signature256:
ctx->cert->sig->hash_algo = "streebog256";
goto ecrdsa;
@@ -255,6 +275,11 @@ int x509_note_pkey_algo(void *context, size_t hdrlen,
ctx->cert->sig->encoding = "raw";
ctx->algo_oid = ctx->last_oid;
return 0;
+ecdsa:
+ ctx->cert->sig->pkey_algo = "ecdsa";
+ ctx->cert->sig->encoding = "x962";
+ ctx->algo_oid = ctx->last_oid;
+ return 0;
}

/*
@@ -276,7 +301,8 @@ int x509_note_signature(void *context, size_t hdrlen,

if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
- strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0) {
+ strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
+ strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
/* Discard the BIT STRING metadata */
if (vlen < 1 || *(const u8 *)value != 0)
return -EBADMSG;
@@ -478,6 +504,12 @@ int x509_extract_key_data(void *context, size_t hdrlen,
case OID_sm2:
ctx->cert->pub->pkey_algo = "sm2";
break;
+ case OID_id_prime192v1:
+ ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
+ break;
+ case OID_id_prime256v1:
+ ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
+ break;
default:
return -ENOPKG;
}
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index ae450eb8be14..3d45161b271a 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -129,7 +129,9 @@ int x509_check_for_self_signed(struct x509_certificate *cert)
}

ret = -EKEYREJECTED;
- if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
+ if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0 &&
+ (strncmp(cert->pub->pkey_algo, "ecdsa-", 6) != 0 ||
+ strcmp(cert->sig->pkey_algo, "ecdsa") != 0))
goto out;

ret = public_key_verify_signature(cert->pub, cert->sig);
diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index f32d91895e4d..3583908cf1ca 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -20,6 +20,8 @@ enum OID {
OID_id_dsa_with_sha1, /* 1.2.840.10030.4.3 */
OID_id_dsa, /* 1.2.840.10040.4.1 */
OID_id_ecPublicKey, /* 1.2.840.10045.2.1 */
+ OID_id_prime192v1, /* 1.2.840.10045.3.1.1 */
+ OID_id_prime256v1, /* 1.2.840.10045.3.1.7 */
OID_id_ecdsa_with_sha1, /* 1.2.840.10045.4.1 */
OID_id_ecdsa_with_sha224, /* 1.2.840.10045.4.3.1 */
OID_id_ecdsa_with_sha256, /* 1.2.840.10045.4.3.2 */
--
2.29.2