X.509: Extract both parts of the AuthorityKeyIdentifier

Extract both parts of the AuthorityKeyIdentifier, not just the keyIdentifier,
as the second part can be used to match X.509 certificates by issuer and
serialNumber.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Vivek Goyal <vgoyal@redhat.com>

7 files changed, 145 insertions, 69 deletions

diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index e47fcd9..cd1406f 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -15,15 +15,21 @@ obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
 obj-$(CONFIG_X509_CERTIFICATE_PARSER) += x509_key_parser.o
 x509_key_parser-y := \
 	x509-asn1.o \
+	x509_akid-asn1.o \
 	x509_rsakey-asn1.o \
 	x509_cert_parser.o \
 	x509_public_key.o
 
-$(obj)/x509_cert_parser.o: $(obj)/x509-asn1.h $(obj)/x509_rsakey-asn1.h
+$(obj)/x509_cert_parser.o: \
+	$(obj)/x509-asn1.h \
+	$(obj)/x509_akid-asn1.h \
+	$(obj)/x509_rsakey-asn1.h
 $(obj)/x509-asn1.o: $(obj)/x509-asn1.c $(obj)/x509-asn1.h
+$(obj)/x509_akid-asn1.o: $(obj)/x509_akid-asn1.c $(obj)/x509_akid-asn1.h
 $(obj)/x509_rsakey-asn1.o: $(obj)/x509_rsakey-asn1.c $(obj)/x509_rsakey-asn1.h
 
 clean-files	+= x509-asn1.c x509-asn1.h
+clean-files	+= x509_akid-asn1.c x509_akid-asn1.h
 clean-files	+= x509_rsakey-asn1.c x509_rsakey-asn1.h
 
 #
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index 1d29376..0f6463b 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -85,8 +85,8 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 	/* No match - see if the root certificate has a signer amongst the
 	 * trusted keys.
 	 */
-	if (last && last->authority) {
-		key = x509_request_asymmetric_key(trust_keyring, last->authority,
+	if (last && last->akid_skid) {
+		key = x509_request_asymmetric_key(trust_keyring, last->akid_skid,
 						  false);
 		if (!IS_ERR(key)) {
 			x509 = last;
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index cd45545..a4d083f 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -187,11 +187,11 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 			goto maybe_missing_crypto_in_x509;
 
 		pr_debug("- issuer %s\n", x509->issuer);
-		if (x509->authority)
+		if (x509->akid_skid)
 			pr_debug("- authkeyid %*phN\n",
-				 x509->authority->len, x509->authority->data);
+				 x509->akid_skid->len, x509->akid_skid->data);
 
-		if (!x509->authority ||
+		if (!x509->akid_skid ||
 		    strcmp(x509->subject, x509->issuer) == 0) {
 			/* If there's no authority certificate specified, then
 			 * the certificate must be self-signed and is the root
@@ -216,13 +216,13 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		 * list to see if the next one is there.
 		 */
 		pr_debug("- want %*phN\n",
-			 x509->authority->len, x509->authority->data);
+			 x509->akid_skid->len, x509->akid_skid->data);
 		for (p = pkcs7->certs; p; p = p->next) {
 			if (!p->skid)
 				continue;
 			pr_debug("- cmp [%u] %*phN\n",
 				 p->index, p->skid->len, p->skid->data);
-			if (asymmetric_key_id_same(p->skid, x509->authority))
+			if (asymmetric_key_id_same(p->skid, x509->akid_skid))
 				goto found_issuer;
 		}
 
@@ -338,8 +338,6 @@ int pkcs7_verify(struct pkcs7_message *pkcs7)
 		ret = x509_get_sig_params(x509);
 		if (ret < 0)
 			return ret;
-		pr_debug("X.509[%u] %*phN\n",
-			 n, x509->authority->len, x509->authority->data);
 	}
 
 	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
diff --git a/crypto/asymmetric_keys/x509_akid.asn1 b/crypto/asymmetric_keys/x509_akid.asn1
new file mode 100644
index 0000000..1a33231
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_akid.asn1
@@ -0,0 +1,35 @@
+-- X.509 AuthorityKeyIdentifier
+-- rfc5280 section 4.2.1.1
+
+AuthorityKeyIdentifier ::= SEQUENCE {
+	keyIdentifier			[0] IMPLICIT KeyIdentifier		OPTIONAL,
+	authorityCertIssuer		[1] IMPLICIT GeneralNames		OPTIONAL,
+	authorityCertSerialNumber	[2] IMPLICIT CertificateSerialNumber	OPTIONAL
+	}
+
+KeyIdentifier ::= OCTET STRING ({ x509_akid_note_kid })
+
+CertificateSerialNumber ::= INTEGER ({ x509_akid_note_serial })
+
+GeneralNames ::= SEQUENCE OF GeneralName
+
+GeneralName ::= CHOICE {
+	otherName			[0] ANY,
+	rfc822Name			[1] IA5String,
+	dNSName				[2] IA5String,
+	x400Address			[3] ANY,
+	directoryName			[4] Name ({ x509_akid_note_name }),
+	ediPartyName			[5] ANY,
+	uniformResourceIdentifier	[6] IA5String,
+	iPAddress			[7] OCTET STRING,
+	registeredID			[8] OBJECT IDENTIFIER
+	}
+
+Name ::= SEQUENCE OF RelativeDistinguishedName
+
+RelativeDistinguishedName ::= SET OF AttributeValueAssertion
+
+AttributeValueAssertion ::= SEQUENCE {
+	attributeType		OBJECT IDENTIFIER ({ x509_note_OID }),
+	attributeValue		ANY ({ x509_extract_name_segment })
+	}
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index a668d90..6c130dd 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -18,6 +18,7 @@
 #include "public_key.h"
 #include "x509_parser.h"
 #include "x509-asn1.h"
+#include "x509_akid-asn1.h"
 #include "x509_rsakey-asn1.h"
 
 struct x509_parse_context {
@@ -35,6 +36,10 @@ struct x509_parse_context {
 	u16		o_offset;		/* Offset of organizationName (O) */
 	u16		cn_offset;		/* Offset of commonName (CN) */
 	u16		email_offset;		/* Offset of emailAddress */
+	unsigned	raw_akid_size;
+	const void	*raw_akid;		/* Raw authorityKeyId in ASN.1 */
+	const void	*akid_raw_issuer;	/* Raw directoryName in authorityKeyId */
+	unsigned	akid_raw_issuer_size;
 };
 
 /*
@@ -48,7 +53,8 @@ void x509_free_certificate(struct x509_certificate *cert)
 		kfree(cert->subject);
 		kfree(cert->id);
 		kfree(cert->skid);
-		kfree(cert->authority);
+		kfree(cert->akid_id);
+		kfree(cert->akid_skid);
 		kfree(cert->sig.digest);
 		mpi_free(cert->sig.rsa.s);
 		kfree(cert);
@@ -85,6 +91,18 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
 	if (ret < 0)
 		goto error_decode;
 
+	/* Decode the AuthorityKeyIdentifier */
+	if (ctx->raw_akid) {
+		pr_devel("AKID: %u %*phN\n",
+			 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
+		ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
+				       ctx->raw_akid, ctx->raw_akid_size);
+		if (ret < 0) {
+			pr_warn("Couldn't decode AuthKeyIdentifier\n");
+			goto error_decode;
+		}
+	}
+
 	/* Decode the public key */
 	ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
 			       ctx->key, ctx->key_size);
@@ -422,7 +440,6 @@ int x509_process_extension(void *context, size_t hdrlen,
 	struct x509_parse_context *ctx = context;
 	struct asymmetric_key_id *kid;
 	const unsigned char *v = value;
-	int i;
 
 	pr_debug("Extension: %u\n", ctx->last_oid);
 
@@ -449,57 +466,8 @@ int x509_process_extension(void *context, size_t hdrlen,
 
 	if (ctx->last_oid == OID_authorityKeyIdentifier) {
 		/* Get hold of the CA key fingerprint */
-		if (ctx->cert->authority || vlen < 5)
-			return -EBADMSG;
-
-		/* Authority Key Identifier must be a Constructed SEQUENCE */
-		if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
-			return -EBADMSG;
-
-		/* Authority Key Identifier is not indefinite length */
-		if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
-			return -EBADMSG;
-
-		if (vlen < ASN1_INDEFINITE_LENGTH) {
-			/* Short Form length */
-			if (v[1] != vlen - 2 ||
-			    v[2] != SEQ_TAG_KEYID ||
-			    v[3] > vlen - 4)
-				return -EBADMSG;
-
-			vlen = v[3];
-			v += 4;
-		} else {
-			/* Long Form length */
-			size_t seq_len = 0;
-			size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
-
-			if (sub > 2)
-				return -EBADMSG;
-
-			/* calculate the length from subsequent octets */
-			v += 2;
-			for (i = 0; i < sub; i++) {
-				seq_len <<= 8;
-				seq_len |= v[i];
-			}
-
-			if (seq_len != vlen - 2 - sub ||
-			    v[sub] != SEQ_TAG_KEYID ||
-			    v[sub + 1] > vlen - 4 - sub)
-				return -EBADMSG;
-
-			vlen = v[sub + 1];
-			v += (sub + 2);
-		}
-
-		kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
-						 ctx->cert->raw_issuer_size,
-						 v, vlen);
-		if (IS_ERR(kid))
-			return PTR_ERR(kid);
-		pr_debug("authkeyid %*phN\n", kid->len, kid->data);
-		ctx->cert->authority = kid;
+		ctx->raw_akid = v;
+		ctx->raw_akid_size = vlen;
 		return 0;
 	}
 
@@ -569,3 +537,71 @@ int x509_note_not_after(void *context, size_t hdrlen,
 	struct x509_parse_context *ctx = context;
 	return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
 }
+
+/*
+ * Note a key identifier-based AuthorityKeyIdentifier
+ */
+int x509_akid_note_kid(void *context, size_t hdrlen,
+		       unsigned char tag,
+		       const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+
+	pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
+
+	if (ctx->cert->akid_skid)
+		return 0;
+
+	kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
+					 ctx->cert->raw_issuer_size,
+					 value, vlen);
+	if (IS_ERR(kid))
+		return PTR_ERR(kid);
+	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+	ctx->cert->akid_skid = kid;
+	return 0;
+}
+
+/*
+ * Note a directoryName in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_name(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("AKID: name: %*phN\n", (int)vlen, value);
+
+	ctx->akid_raw_issuer = value;
+	ctx->akid_raw_issuer_size = vlen;
+	return 0;
+}
+
+/*
+ * Note a serial number in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_serial(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+
+	pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
+
+	if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
+		return 0;
+
+	kid = asymmetric_key_generate_id(value,
+					 vlen,
+					 ctx->akid_raw_issuer,
+					 ctx->akid_raw_issuer_size);
+	if (IS_ERR(kid))
+		return PTR_ERR(kid);
+
+	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+	ctx->cert->akid_id = kid;
+	return 0;
+}
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 3dfe6b5..dcdb5c9 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -19,9 +19,10 @@ struct x509_certificate {
 	struct public_key_signature sig;	/* Signature parameters */
 	char		*issuer;		/* Name of certificate issuer */
 	char		*subject;		/* Name of certificate subject */
-	struct asymmetric_key_id *id;		/* Serial number + issuer */
+	struct asymmetric_key_id *id;		/* Issuer + Serial number */
 	struct asymmetric_key_id *skid;		/* Subject + subjectKeyId (optional) */
-	struct asymmetric_key_id *authority;	/* Authority key identifier (optional) */
+	struct asymmetric_key_id *akid_id;	/* CA AuthKeyId matching ->id (optional) */
+	struct asymmetric_key_id *akid_skid;	/* CA AuthKeyId matching ->skid (optional) */
 	struct tm	valid_from;
 	struct tm	valid_to;
 	const void	*tbs;			/* Signed data */
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 24f17e6..bb55d60 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -227,10 +227,10 @@ static int x509_validate_trust(struct x509_certificate *cert,
 	if (!trust_keyring)
 		return -EOPNOTSUPP;
 
-	if (ca_keyid && !asymmetric_key_id_partial(cert->authority, ca_keyid))
+	if (ca_keyid && !asymmetric_key_id_partial(cert->akid_skid, ca_keyid))
 		return -EPERM;
 
-	key = x509_request_asymmetric_key(trust_keyring, cert->authority,
+	key = x509_request_asymmetric_key(trust_keyring, cert->akid_skid,
 					  false);
 	if (!IS_ERR(key))  {
 		if (!use_builtin_keys
@@ -287,8 +287,8 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 	cert->pub->id_type = PKEY_ID_X509;
 
 	/* Check the signature on the key if it appears to be self-signed */
-	if (!cert->authority ||
-	    asymmetric_key_id_same(cert->skid, cert->authority)) {
+	if (!cert->akid_skid ||
+	    asymmetric_key_id_same(cert->skid, cert->akid_skid)) {
 		ret = x509_check_signature(cert->pub, cert); /* self-signed */
 		if (ret < 0)
 			goto error_free_cert;