Per X.509 spec in 4.2.1.1 section, the structure of Authority Key
Identifier Extension is:
AuthorityKeyIdentifier ::= SEQUENCE {
keyIdentifier [0] KeyIdentifier OPTIONAL,
authorityCertIssuer [1] GeneralNames OPTIONAL,
authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL }
KeyIdentifier ::= OCTET STRING
When a certificate also provides
authorityCertIssuer and authorityCertSerialNumber then the length of
AuthorityKeyIdentifier SEQUENCE is likely to long form format.
e.g.
The example certificate demos/tunala/A-server.pem in openssl source:
X509v3 Authority Key Identifier:
keyid:49:FB:45:72:12:C4:CC:E1:45:A1:D3:08:9E:95:C4:2C:6D:55:3F:17
DirName:/C=NZ/L=Wellington/O=Really Irresponsible Authorisation Authority
(RIAA)/OU=Cert-stamping/CN=Jackov al-Trades/emailAddress=none@fake.domain
serial:00
Current parsing rule of OID_authorityKeyIdentifier only take care the
short form format, it causes load certificate to modsign_keyring fail:
[ 12.061147] X.509: Extension: 47
[ 12.075121] MODSIGN: Problem loading in-kernel X.509 certificate (-74)
So, this patch add the parsing rule for support long form format against
Authority Key Identifier.
v2:
- Removed comma from author's name.
- Moved 'Short Form length' comment inside the if-body.
- Changed the type of sub to size_t.
- Use ASN1_INDEFINITE_LENGTH rather than writing 0x80 and 127.
- Moved the key_len's value assignment before alter v.
- Fixed the typo of octets.
- Add 2 to v before entering the loop for calculate the length.
- Removed the comment of check vlen.
Cc: David Howells <dhowe...@redhat.com>
Cc: Rusty Russell <ru...@rustcorp.com.au>
Cc: Josh Boyer <jwbo...@redhat.com>
Cc: Randy Dunlap <rdun...@xenotime.net>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: "David S. Miller" <da...@davemloft.net>
Signed-off-by: Chun-Yi Lee <j...@suse.com>
---
crypto/asymmetric_keys/x509_cert_parser.c | 55 ++++++++++++++++++++++++----
1 files changed, 47 insertions(+), 8 deletions(-)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c
b/crypto/asymmetric_keys/x509_cert_parser.c
index 7fabc4c..59ab6d2 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -373,6 +373,9 @@ int rsa_extract_mpi(void *context, size_t hdrlen,
return 0;
}
+/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
+#define SEQ_TAG_KEYID (ASN1_CONT << 6)
+
/*
* Process certificate extensions that are used to qualify the certificate.
*/
@@ -407,21 +410,57 @@ int x509_process_extension(void *context, size_t hdrlen,
}
if (ctx->last_oid == OID_authorityKeyIdentifier) {
+ size_t key_len;
+
/* Get hold of the CA key fingerprint */
if (vlen < 5)
return -EBADMSG;
- if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)) ||
- v[1] != vlen - 2 ||
- v[2] != (ASN1_CONT << 6) ||
- v[3] != vlen - 4)
+
+ /* Authority Key Identifier must be a Constructed SEQUENCE */
+ if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
return -EBADMSG;
- v += 4;
- vlen -= 4;
- f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
+ /* 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;
+
+ key_len = 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;
+
+ key_len = v[sub + 1];
+ v += (sub + 2);
+ }
+
+ f = kmalloc(key_len * 2 + 1, GFP_KERNEL);
if (!f)
return -ENOMEM;
- for (i = 0; i < vlen; i++)
+ for (i = 0; i < key_len; i++)
sprintf(f + i * 2, "%02x", v[i]);
pr_debug("authority %s\n", f);
ctx->cert->authority = f;
--
1.6.4.2
--
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