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author | Chun-Yi Lee <jlee@suse.com> | 2013-04-22 03:26:55 +0200 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2013-04-22 04:02:19 +0200 |
commit | 04b00bdb41d0fd8d9cf3b146e334369cc2b0acdc (patch) | |
tree | 9461c5a4a47493ffa85c418ee6bdef1f8925d437 /crypto | |
parent | module: don't unlink the module until we've removed all exposure. (diff) | |
download | linux-04b00bdb41d0fd8d9cf3b146e334369cc2b0acdc.tar.xz linux-04b00bdb41d0fd8d9cf3b146e334369cc2b0acdc.zip |
X.509: Support parse long form of length octets in Authority Key Identifier
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.
v3:
Changed the size check in "Short Form length" case, we allow v[3] smaller
then (vlen - 4) because authorityCertIssuer and authorityCertSerialNumber
are also possible attach in AuthorityKeyIdentifier sequence.
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: Rusty Russell <rusty@rustcorp.com.au>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Chun-Yi Lee <jlee@suse.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'crypto')
-rw-r--r-- | 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 7fabc4c01993..facbf26bc6bb 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; |