From 46963b774d441c833afc1535f6d84b3df2a94204 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 16 Sep 2014 17:36:13 +0100 Subject: KEYS: Overhaul key identification when searching for asymmetric keys Make use of the new match string preparsing to overhaul key identification when searching for asymmetric keys. The following changes are made: (1) Use the previously created asymmetric_key_id struct to hold the following key IDs derived from the X.509 certificate or PKCS#7 message: id: serial number + issuer skid: subjKeyId + subject authority: authKeyId + issuer (2) Replace the hex fingerprint attached to key->type_data[1] with an asymmetric_key_ids struct containing the id and the skid (if present). (3) Make the asymmetric_type match data preparse select one of two searches: (a) An iterative search for the key ID given if prefixed with "id:". The prefix is expected to be followed by a hex string giving the ID to search for. The criterion key ID is checked against all key IDs recorded on the key. (b) A direct search if the key ID is not prefixed with "id:". This will look for an exact match on the key description. (4) Make x509_request_asymmetric_key() take a key ID. This is then converted into "id:" and passed into keyring_search() where match preparsing will turn it back into a binary ID. (5) X.509 certificate verification then takes the authority key ID and looks up a key that matches it to find the public key for the certificate signature. (6) PKCS#7 certificate verification then takes the id key ID and looks up a key that matches it to find the public key for the signed information block signature. Additional changes: (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the cert to be rejected with -EBADMSG. (2) The 'fingerprint' ID is gone. This was primarily intended to convey PGP public key fingerprints. If PGP is supported in future, this should generate a key ID that carries the fingerprint. (3) Th ca_keyid= kernel command line option is now converted to a key ID and used to match the authority key ID. Possibly this should only match the actual authKeyId part and not the issuer as well. Signed-off-by: David Howells Acked-by: Vivek Goyal --- crypto/asymmetric_keys/x509_public_key.c | 89 ++++++++++++++++++-------------- 1 file changed, 51 insertions(+), 38 deletions(-) (limited to 'crypto/asymmetric_keys/x509_public_key.c') diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c index f3d62307e6ee..c60905c3f4d2 100644 --- a/crypto/asymmetric_keys/x509_public_key.c +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -25,7 +25,7 @@ #include "x509_parser.h" static bool use_builtin_keys; -static char *ca_keyid; +static struct asymmetric_key_id *ca_keyid; #ifndef MODULE static int __init ca_keys_setup(char *str) @@ -33,10 +33,16 @@ static int __init ca_keys_setup(char *str) if (!str) /* default system keyring */ return 1; - if (strncmp(str, "id:", 3) == 0) - ca_keyid = str; /* owner key 'id:xxxxxx' */ - else if (strcmp(str, "builtin") == 0) + if (strncmp(str, "id:", 3) == 0) { + struct asymmetric_key_id *p; + p = asymmetric_key_hex_to_key_id(str); + if (p == ERR_PTR(-EINVAL)) + pr_err("Unparsable hex string in ca_keys\n"); + else if (!IS_ERR(p)) + ca_keyid = p; /* owner key 'id:xxxxxx' */ + } else if (strcmp(str, "builtin") == 0) { use_builtin_keys = true; + } return 1; } @@ -46,31 +52,28 @@ __setup("ca_keys=", ca_keys_setup); /** * x509_request_asymmetric_key - Request a key by X.509 certificate params. * @keyring: The keys to search. - * @subject: The name of the subject to whom the key belongs. - * @key_id: The subject key ID as a hex string. + * @kid: The key ID. * * Find a key in the given keyring by subject name and key ID. These might, * for instance, be the issuer name and the authority key ID of an X.509 * certificate that needs to be verified. */ struct key *x509_request_asymmetric_key(struct key *keyring, - const char *subject, - const char *key_id) + const struct asymmetric_key_id *kid) { key_ref_t key; - size_t subject_len = strlen(subject), key_id_len = strlen(key_id); - char *id; + char *id, *p; - /* Construct an identifier ":". */ - id = kmalloc(subject_len + 2 + key_id_len + 1, GFP_KERNEL); + /* Construct an identifier "id:". */ + p = id = kmalloc(2 + 1 + kid->len * 2 + 1, GFP_KERNEL); if (!id) return ERR_PTR(-ENOMEM); - memcpy(id, subject, subject_len); - id[subject_len + 0] = ':'; - id[subject_len + 1] = ' '; - memcpy(id + subject_len + 2, key_id, key_id_len); - id[subject_len + 2 + key_id_len] = 0; + *p++ = 'i'; + *p++ = 'd'; + *p++ = ':'; + p = bin2hex(p, kid->data, kid->len); + *p = 0; pr_debug("Look up: \"%s\"\n", id); @@ -195,11 +198,10 @@ static int x509_validate_trust(struct x509_certificate *cert, if (!trust_keyring) return -EOPNOTSUPP; - if (ca_keyid && !asymmetric_keyid_match(cert->authority, ca_keyid)) + if (ca_keyid && !asymmetric_key_id_same(cert->authority, ca_keyid)) return -EPERM; - key = x509_request_asymmetric_key(trust_keyring, - cert->issuer, cert->authority); + key = x509_request_asymmetric_key(trust_keyring, cert->authority); if (!IS_ERR(key)) { if (!use_builtin_keys || test_bit(KEY_FLAG_BUILTIN, &key->flags)) @@ -214,9 +216,11 @@ static int x509_validate_trust(struct x509_certificate *cert, */ static int x509_key_preparse(struct key_preparsed_payload *prep) { + struct asymmetric_key_ids *kids; struct x509_certificate *cert; + const char *q; size_t srlen, sulen; - char *desc = NULL; + char *desc = NULL, *p; int ret; cert = x509_cert_parse(prep->data, prep->datalen); @@ -249,19 +253,12 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) pkey_algo_name[cert->sig.pkey_algo], hash_algo_name[cert->sig.pkey_hash_algo]); - if (!cert->fingerprint) { - pr_warn("Cert for '%s' must have a SubjKeyId extension\n", - cert->subject); - ret = -EKEYREJECTED; - goto error_free_cert; - } - cert->pub->algo = pkey_algo[cert->pub->pkey_algo]; cert->pub->id_type = PKEY_ID_X509; /* Check the signature on the key if it appears to be self-signed */ if (!cert->authority || - strcmp(cert->fingerprint, cert->authority) == 0) { + asymmetric_key_id_same(cert->skid, cert->authority)) { ret = x509_check_signature(cert->pub, cert); /* self-signed */ if (ret < 0) goto error_free_cert; @@ -273,31 +270,47 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) /* Propose a description */ sulen = strlen(cert->subject); - srlen = strlen(cert->fingerprint); + srlen = cert->raw_serial_size; + q = cert->raw_serial; + if (srlen > 1 && *q == 0) { + srlen--; + q++; + } + ret = -ENOMEM; - desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL); + desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); if (!desc) goto error_free_cert; - memcpy(desc, cert->subject, sulen); - desc[sulen] = ':'; - desc[sulen + 1] = ' '; - memcpy(desc + sulen + 2, cert->fingerprint, srlen); - desc[sulen + 2 + srlen] = 0; + p = memcpy(desc, cert->subject, sulen); + p += sulen; + *p++ = ':'; + *p++ = ' '; + p = bin2hex(p, q, srlen); + *p = 0; + + kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); + if (!kids) + goto error_free_desc; + kids->id[0] = cert->id; + kids->id[1] = cert->skid; /* We're pinning the module by being linked against it */ __module_get(public_key_subtype.owner); prep->type_data[0] = &public_key_subtype; - prep->type_data[1] = cert->fingerprint; + prep->type_data[1] = kids; prep->payload[0] = cert->pub; prep->description = desc; prep->quotalen = 100; /* We've finished with the certificate */ cert->pub = NULL; - cert->fingerprint = NULL; + cert->id = NULL; + cert->skid = NULL; desc = NULL; ret = 0; +error_free_desc: + kfree(desc); error_free_cert: x509_free_certificate(cert); return ret; -- cgit