[PATCH v2 01/10] cert/key: Add support for EC based certificates

[Denis Kenzior <denkenz@gmail.com>]

Mostly for use with Elliptic Curve (EC) Digital Signature
Algorithm (DSA) based certificates.  Other combinations of EC +
signature algorithms are also possible.

This requires your kernel to be built with CRYPTO_ECDSA support.
---
NOTE: At the time this patch was created, kernel had to be patched with
the following fix in order for ECDSA support to function properly from
userspace:
https://lore.kernel.org/linux-crypto/20220715182810.30505-1-denkenz@gmail.com/

 ell/cert.c | 18 ++++++++++++++++--
 ell/cert.h |  1 +
 ell/key.c  |  1 +
 ell/key.h  |  1 +
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/ell/cert.c b/ell/cert.c
index 141ea1cec038..a158142445ec 100644
--- a/ell/cert.c
+++ b/ell/cert.c
@@ -77,7 +77,15 @@ static const struct pkcs1_encryption_oid {
 } pkcs1_encryption_oids[] = {
 	{ /* rsaEncryption */
 		L_CERT_KEY_RSA,
-		{ 9, { 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01 } },
+		{ .asn1_len = 9, .asn1 = {
+			0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01 }
+		},
+	},
+	{ /* ecPublicKey */
+		L_CERT_KEY_ECC,
+		{ .asn1_len = 7, .asn1 = {
+			0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01 }
+		},
 	},
 };
 
@@ -261,8 +269,14 @@ LIB_EXPORT struct l_key *l_cert_get_pubkey(struct l_cert *cert)
 		return NULL;
 
 	/* Use kernel's ASN.1 certificate parser to find the key data for us */
-	if (cert->pubkey_type == L_CERT_KEY_RSA)
+	switch (cert->pubkey_type) {
+	case L_CERT_KEY_RSA:
 		return l_key_new(L_KEY_RSA, cert->asn1, cert->asn1_len);
+	case L_CERT_KEY_ECC:
+		return l_key_new(L_KEY_ECC, cert->asn1, cert->asn1_len);
+	case L_CERT_KEY_UNKNOWN:
+		break;
+	}
 
 	return NULL;
 }
diff --git a/ell/cert.h b/ell/cert.h
index 605e427c3d05..f637588e6d66 100644
--- a/ell/cert.h
+++ b/ell/cert.h
@@ -36,6 +36,7 @@ struct l_certchain;
 
 enum l_cert_key_type {
 	L_CERT_KEY_RSA,
+	L_CERT_KEY_ECC,
 	L_CERT_KEY_UNKNOWN,
 };
 
diff --git a/ell/key.c b/ell/key.c
index b28bf4dbf085..73f38581f736 100644
--- a/ell/key.c
+++ b/ell/key.c
@@ -108,6 +108,7 @@ struct l_keyring {
 static const char * const key_type_names[] = {
 	[L_KEY_RAW] = "user",
 	[L_KEY_RSA] = "asymmetric",
+	[L_KEY_ECC] = "asymmetric",
 };
 
 static long kernel_add_key(const char *type, const char *description,
diff --git a/ell/key.h b/ell/key.h
index d25d09385b6f..f26f7ecb26c3 100644
--- a/ell/key.h
+++ b/ell/key.h
@@ -45,6 +45,7 @@ enum l_key_feature {
 enum l_key_type {
 	L_KEY_RAW = 0,
 	L_KEY_RSA,
+	L_KEY_ECC,
 };
 
 enum l_keyring_restriction {
-- 
2.35.1