[PATCH v7 3/4] x509: Add support for parsing x509 certs with ECDSA keys

From: Stefan Berger
Date: Mon Feb 01 2021 - 10:25:45 EST


This patch adds 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.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: keyrings@xxxxxxxxxxxxxxx
---
crypto/asymmetric_keys/public_key.c | 19 ++++++++++++++
crypto/asymmetric_keys/x509_cert_parser.c | 32 ++++++++++++++++++++++-
include/linux/oid_registry.h | 2 ++
3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 8892908ad58c..7dae61b79d5a 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>
@@ -90,6 +91,24 @@ int software_key_determine_akcipher(const char *encoding,
return 0;
}

+ if (strcmp(encoding, "x962") == 0) {
+ enum OID oid;
+
+ if (parse_OID(pkey->params, pkey->paramlen, &oid) != 0)
+ return -EBADMSG;
+
+ switch (oid) {
+ case OID_id_prime192v1:
+ strcpy(alg_name, "ecdsa-nist-p192");
+ return 0;
+ case OID_id_prime256v1:
+ strcpy(alg_name, "ecdsa-nist-p256");
+ return 0;
+ default:
+ return -EINVAL;
+ }
+ }
+
return -ENOPKG;
}

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 1621ceaf5c95..0aff4e584b11 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 +504,10 @@ int x509_extract_key_data(void *context, size_t hdrlen,
case OID_sm2:
ctx->cert->pub->pkey_algo = "sm2";
break;
+ case OID_id_prime192v1:
+ case OID_id_prime256v1:
+ ctx->cert->pub->pkey_algo = "ecdsa";
+ break;
default:
return -ENOPKG;
}
diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index f3b2c097c886..ff3cad9f8c1f 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -21,6 +21,8 @@ enum OID {
OID_id_dsa, /* 1.2.840.10040.4.1 */
OID_id_ecdsa_with_sha1, /* 1.2.840.10045.4.1 */
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_sha224, /* 1.2.840.10045.4.3.1 */
OID_id_ecdsa_with_sha256, /* 1.2.840.10045.4.3.2 */
OID_id_ecdsa_with_sha384, /* 1.2.840.10045.4.3.3 */
--
2.29.2