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:<hex>" 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 <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index f3d6230..c60905c 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 @@
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 @@
/**
* 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 "<subjname>:<keyid>". */
- id = kmalloc(subject_len + 2 + key_id_len + 1, GFP_KERNEL);
+ /* Construct an identifier "id:<keyid>". */
+ 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 @@
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_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 @@
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 @@
/* 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;