Messages in this thread Patch in this message |  | | From | "Lee, Chun-Yi" <> | Subject | [PATCH] X.509: Support parse long form of length octets in Authority Key Identifier | Date | Wed, 6 Feb 2013 13:58:21 +0800 |
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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.
Cc: David Howells <dhowells@redhat.com> 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> Signed-off-by: Lee, Chun-Yi <jlee@suse.com> --- crypto/asymmetric_keys/x509_cert_parser.c | 56 ++++++++++++++++++++++++---- 1 files changed, 48 insertions(+), 8 deletions(-)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 7fabc4c..7f6a152 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 +410,58 @@ 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; + + /* Short Form length */ + if (vlen <= 127) { + + if (v[1] != vlen - 2 || + v[2] != SEQ_TAG_KEYID || + v[3] != vlen - 4) + return -EBADMSG; + + v += 4; + key_len = v[3]; + } else { + /* Long Form length */ + size_t seq_len = 0; + int sub = v[1] - 0x80; + + if (sub > 2) + return -EBADMSG; + + /* calculate the length from subsequent octet */ + for (i = 0; i < sub; i++) { + seq_len <<= 8; + seq_len |= v[2 + i]; + } + + /* check vlen should not less then length of keyid */ + if (seq_len != vlen - 2 - sub || + v[2 + sub] != SEQ_TAG_KEYID || + v[3 + sub] > vlen - 4 - sub) + return -EBADMSG; + + v += (4 + sub); + key_len = v[3 + sub]; + } + + 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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