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>

9 files changed, 195 insertions, 184 deletions

diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h
index 917be6b985e7..fd21ac28e0a0 100644
--- a/crypto/asymmetric_keys/asymmetric_keys.h
+++ b/crypto/asymmetric_keys/asymmetric_keys.h
@@ -9,13 +9,13 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
-int asymmetric_keyid_match(const char *kid, const char *id);
 extern bool asymmetric_match_key_ids(const struct asymmetric_key_ids *kids,
                                      const struct asymmetric_key_id *match_id);
 
 extern struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id);
 
-static inline const char *asymmetric_key_id(const struct key *key)
+static inline
+const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
 {
         return key->type_data.p[1];
 }
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index 92bfc438dd1d..718e779a010e 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -112,76 +112,15 @@ struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
 }
 
 /*
- * Match asymmetric key id with partial match
- * @id:         key id to match in a form "id:<id>"
- */
-int asymmetric_keyid_match(const char *kid, const char *id)
-{
-        size_t idlen, kidlen;
-
-        if (!kid || !id)
-                return 0;
-
-        /* make it possible to use id as in the request: "id:<id>" */
-        if (strncmp(id, "id:", 3) == 0)
-                id += 3;
-
-        /* Anything after here requires a partial match on the ID string */
-        idlen = strlen(id);
-        kidlen = strlen(kid);
-        if (idlen > kidlen)
-                return 0;
-
-        kid += kidlen - idlen;
-        if (strcasecmp(id, kid) != 0)
-                return 0;
-
-        return 1;
-}
-EXPORT_SYMBOL_GPL(asymmetric_keyid_match);
-
-/*
- * Match asymmetric keys on (part of) their name
- * We have some shorthand methods for matching keys.  We allow:
- *
- *      "<desc>"        - request a key by description
- *      "id:<id>"       - request a key matching the ID
- *      "<subtype>:<id>" - request a key of a subtype
+ * Match asymmetric keys by ID.
  */
 static bool asymmetric_key_cmp(const struct key *key,
                                const struct key_match_data *match_data)
 {
-        const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
-        const char *description = match_data->raw_data;
-        const char *spec = description;
-        const char *id;
-        ptrdiff_t speclen;
-
-        if (!subtype || !spec || !*spec)
-                return 0;
-
-        /* See if the full key description matches as is */
-        if (key->description && strcmp(key->description, description) == 0)
-                return 1;
-
-        /* All tests from here on break the criterion description into a
-         * specifier, a colon and then an identifier.
-         */
-        id = strchr(spec, ':');
-        if (!id)
-                return 0;
-
-        speclen = id - spec;
-        id++;
-
-        if (speclen == 2 && memcmp(spec, "id", 2) == 0)
-                return asymmetric_keyid_match(asymmetric_key_id(key), id);
+        const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+        const struct asymmetric_key_id *match_id = match_data->preparsed;
 
-        if (speclen == subtype->name_len &&
-            memcmp(spec, subtype->name, speclen) == 0)
-                return 1;
-
-        return 0;
+        return asymmetric_match_key_ids(kids, match_id);
 }
 
 /*
@@ -198,8 +137,30 @@ static bool asymmetric_key_cmp(const struct key *key,
  */
 static int asymmetric_key_match_preparse(struct key_match_data *match_data)
 {
-        match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
+        struct asymmetric_key_id *match_id;
+        const char *spec = match_data->raw_data;
+        const char *id;
+
+        if (!spec || !*spec)
+                return -EINVAL;
+        if (spec[0] == 'i' &&
+            spec[1] == 'd' &&
+            spec[2] == ':') {
+                id = spec + 3;
+        } else {
+                goto default_match;
+        }
+
+        match_id = asymmetric_key_hex_to_key_id(id);
+        if (!match_id)
+                return -ENOMEM;
+
+        match_data->preparsed = match_id;
         match_data->cmp = asymmetric_key_cmp;
+        match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
+        return 0;
+
+default_match:
         return 0;
 }
 
@@ -208,6 +169,7 @@ static int asymmetric_key_match_preparse(struct key_match_data *match_data)
  */
 static void asymmetric_key_match_free(struct key_match_data *match_data)
 {
+        kfree(match_data->preparsed);
 }
 
 /*
@@ -216,8 +178,10 @@ static void asymmetric_key_match_free(struct key_match_data *match_data)
 static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
 {
         const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
-        const char *kid = asymmetric_key_id(key);
-        size_t n;
+        const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+        const struct asymmetric_key_id *kid;
+        const unsigned char *p;
+        int n;
 
         seq_puts(m, key->description);
 
@@ -225,13 +189,16 @@ static void asymmetric_key_describe(const struct key *key, struct seq_file *m)
                 seq_puts(m, ": ");
                 subtype->describe(key, m);
 
-                if (kid) {
+                if (kids && kids->id[0]) {
+                        kid = kids->id[0];
                         seq_putc(m, ' ');
-                        n = strlen(kid);
-                        if (n <= 8)
-                                seq_puts(m, kid);
-                        else
-                                seq_puts(m, kid + n - 8);
+                        n = kid->len;
+                        p = kid->data;
+                        if (n > 8) {
+                                p += n - 8;
+                                n = 8;
+                        }
+                        seq_printf(m, "%*phN", n, p);
                 }
 
                 seq_puts(m, " [");
@@ -282,6 +249,7 @@ static int asymmetric_key_preparse(struct key_preparsed_payload *prep)
 static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
 {
         struct asymmetric_key_subtype *subtype = prep->type_data[0];
+        struct asymmetric_key_ids *kids = prep->type_data[1];
 
         pr_devel("==>%s()\n", __func__);
 
@@ -289,7 +257,11 @@ static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
                 subtype->destroy(prep->payload[0]);
                 module_put(subtype->owner);
         }
-        kfree(prep->type_data[1]);
+        if (kids) {
+                kfree(kids->id[0]);
+                kfree(kids->id[1]);
+                kfree(kids);
+        }
         kfree(prep->description);
 }
 
@@ -299,13 +271,20 @@ static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
 static void asymmetric_key_destroy(struct key *key)
 {
         struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
+        struct asymmetric_key_ids *kids = key->type_data.p[1];
+
         if (subtype) {
                 subtype->destroy(key->payload.data);
                 module_put(subtype->owner);
                 key->type_data.p[0] = NULL;
         }
-        kfree(key->type_data.p[1]);
-        key->type_data.p[1] = NULL;
+
+        if (kids) {
+                kfree(kids->id[0]);
+                kfree(kids->id[1]);
+                kfree(kids);
+                key->type_data.p[1] = NULL;
+        }
 }
 
 struct key_type key_type_asymmetric = {
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 1e9861da7ee4..3bd5a1e4c493 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -29,6 +29,10 @@ struct pkcs7_parse_context {
         enum OID        last_oid;               /* Last OID encountered */
         unsigned        x509_index;
         unsigned        sinfo_index;
+        const void      *raw_serial;
+        unsigned        raw_serial_size;
+        unsigned        raw_issuer_size;
+        const void      *raw_issuer;
 };
 
 /*
@@ -39,6 +43,7 @@ static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
         if (sinfo) {
                 mpi_free(sinfo->sig.mpi[0]);
                 kfree(sinfo->sig.digest);
+                kfree(sinfo->signing_cert_id);
                 kfree(sinfo);
         }
 }
@@ -251,10 +256,10 @@ int pkcs7_extract_cert(void *context, size_t hdrlen,
         if (IS_ERR(x509))
                 return PTR_ERR(x509);
 
-        pr_debug("Got cert for %s\n", x509->subject);
-        pr_debug("- fingerprint %s\n", x509->fingerprint);
-
         x509->index = ++ctx->x509_index;
+        pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
+        pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
+
         *ctx->ppcerts = x509;
         ctx->ppcerts = &x509->next;
         return 0;
@@ -343,8 +348,8 @@ int pkcs7_sig_note_serial(void *context, size_t hdrlen,
                           const void *value, size_t vlen)
 {
         struct pkcs7_parse_context *ctx = context;
-        ctx->sinfo->raw_serial = value;
-        ctx->sinfo->raw_serial_size = vlen;
+        ctx->raw_serial = value;
+        ctx->raw_serial_size = vlen;
         return 0;
 }
 
@@ -356,8 +361,8 @@ int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
                           const void *value, size_t vlen)
 {
         struct pkcs7_parse_context *ctx = context;
-        ctx->sinfo->raw_issuer = value;
-        ctx->sinfo->raw_issuer_size = vlen;
+        ctx->raw_issuer = value;
+        ctx->raw_issuer_size = vlen;
         return 0;
 }
 
@@ -390,10 +395,21 @@ int pkcs7_note_signed_info(void *context, size_t hdrlen,
                            const void *value, size_t vlen)
 {
         struct pkcs7_parse_context *ctx = context;
-
-        ctx->sinfo->index = ++ctx->sinfo_index;
-        *ctx->ppsinfo = ctx->sinfo;
-        ctx->ppsinfo = &ctx->sinfo->next;
+        struct pkcs7_signed_info *sinfo = ctx->sinfo;
+        struct asymmetric_key_id *kid;
+
+        /* Generate cert issuer + serial number key ID */
+        kid = asymmetric_key_generate_id(ctx->raw_serial,
+                                         ctx->raw_serial_size,
+                                         ctx->raw_issuer,
+                                         ctx->raw_issuer_size);
+        if (IS_ERR(kid))
+                return PTR_ERR(kid);
+
+        sinfo->signing_cert_id = kid;
+        sinfo->index = ++ctx->sinfo_index;
+        *ctx->ppsinfo = sinfo;
+        ctx->ppsinfo = &sinfo->next;
         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
         if (!ctx->sinfo)
                 return -ENOMEM;
diff --git a/crypto/asymmetric_keys/pkcs7_parser.h b/crypto/asymmetric_keys/pkcs7_parser.h
index d25f4d15370f..91949f92bc72 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.h
+++ b/crypto/asymmetric_keys/pkcs7_parser.h
@@ -33,10 +33,7 @@ struct pkcs7_signed_info {
         const void      *authattrs;
 
         /* Issuing cert serial number and issuer's name */
-        const void      *raw_serial;
-        unsigned        raw_serial_size;
-        unsigned        raw_issuer_size;
-        const void      *raw_issuer;
+        struct asymmetric_key_id *signing_cert_id;
 
         /* Message signature.
          *
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index fad888ea4fad..09197e50fa82 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -49,8 +49,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
                 /* Look to see if this certificate is present in the trusted
                  * keys.
                  */
-                key = x509_request_asymmetric_key(trust_keyring, x509->subject,
-                                                  x509->fingerprint);
+                key = x509_request_asymmetric_key(trust_keyring, x509->id);
                 if (!IS_ERR(key))
                         /* One of the X.509 certificates in the PKCS#7 message
                          * is apparently the same as one we already trust.
@@ -82,8 +81,7 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
                 return -ENOKEY;
         }
 
-        key = x509_request_asymmetric_key(trust_keyring, last->issuer,
-                                          last->authority);
+        key = x509_request_asymmetric_key(trust_keyring, last->authority);
         if (IS_ERR(key))
                 return PTR_ERR(key) == -ENOMEM ? -ENOMEM : -ENOKEY;
         x509 = last;
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index c62cf8006e1f..57e90fa17f2b 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -131,8 +131,7 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
         struct x509_certificate *x509;
         unsigned certix = 1;
 
-        kenter("%u,%u,%u",
-               sinfo->index, sinfo->raw_serial_size, sinfo->raw_issuer_size);
+        kenter("%u", sinfo->index);
 
         for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
                 /* I'm _assuming_ that the generator of the PKCS#7 message will
@@ -140,21 +139,11 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
                  * PKCS#7 message - but I can't be 100% sure of that.  It's
                  * possible this will need element-by-element comparison.
                  */
-                if (x509->raw_serial_size != sinfo->raw_serial_size ||
-                    memcmp(x509->raw_serial, sinfo->raw_serial,
-                           sinfo->raw_serial_size) != 0)
+                if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
                         continue;
                 pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
                          sinfo->index, certix);
 
-                if (x509->raw_issuer_size != sinfo->raw_issuer_size ||
-                    memcmp(x509->raw_issuer, sinfo->raw_issuer,
-                           sinfo->raw_issuer_size) != 0) {
-                        pr_warn("Sig %u: X.509 subject and PKCS#7 issuer don't match\n",
-                                sinfo->index);
-                        continue;
-                }
-
                 if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
                         pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
                                 sinfo->index);
@@ -164,8 +153,10 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
                 sinfo->signer = x509;
                 return 0;
         }
+
         pr_warn("Sig %u: Issuing X.509 cert not found (#%*ph)\n",
-                sinfo->index, sinfo->raw_serial_size, sinfo->raw_serial);
+                sinfo->index,
+                sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
         return -ENOKEY;
 }
 
@@ -184,7 +175,9 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
                 p->seen = false;
 
         for (;;) {
-                pr_debug("verify %s: %s\n", x509->subject, x509->fingerprint);
+                pr_debug("verify %s: %*phN\n",
+                         x509->subject,
+                         x509->raw_serial_size, x509->raw_serial);
                 x509->seen = true;
                 ret = x509_get_sig_params(x509);
                 if (ret < 0)
@@ -192,7 +185,8 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 
                 pr_debug("- issuer %s\n", x509->issuer);
                 if (x509->authority)
-                        pr_debug("- authkeyid %s\n", x509->authority);
+                        pr_debug("- authkeyid %*phN\n",
+                                 x509->authority->len, x509->authority->data);
 
                 if (!x509->authority ||
                     strcmp(x509->subject, x509->issuer) == 0) {
@@ -218,13 +212,14 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
                 /* Look through the X.509 certificates in the PKCS#7 message's
                  * list to see if the next one is there.
                  */
-                pr_debug("- want %s\n", x509->authority);
+                pr_debug("- want %*phN\n",
+                         x509->authority->len, x509->authority->data);
                 for (p = pkcs7->certs; p; p = p->next) {
-                        pr_debug("- cmp [%u] %s\n", p->index, p->fingerprint);
-                        if (p->raw_subject_size == x509->raw_issuer_size &&
-                            strcmp(p->fingerprint, x509->authority) == 0 &&
-                            memcmp(p->raw_subject, x509->raw_issuer,
-                                   x509->raw_issuer_size) == 0)
+                        if (!p->skid)
+                                continue;
+                        pr_debug("- cmp [%u] %*phN\n",
+                                 p->index, p->skid->len, p->skid->data);
+                        if (asymmetric_key_id_same(p->skid, x509->authority))
                                 goto found_issuer;
                 }
 
@@ -233,7 +228,7 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
                 return 0;
 
         found_issuer:
-                pr_debug("- issuer %s\n", p->subject);
+                pr_debug("- subject %s\n", p->subject);
                 if (p->seen) {
                         pr_warn("Sig %u: X.509 chain contains loop\n",
                                 sinfo->index);
@@ -304,7 +299,8 @@ int pkcs7_verify(struct pkcs7_message *pkcs7)
                 ret = x509_get_sig_params(x509);
                 if (ret < 0)
                         return ret;
-                pr_debug("X.509[%u] %s\n", n, x509->authority);
+                pr_debug("X.509[%u] %*phN\n",
+                         n, x509->authority->len, x509->authority->data);
         }
 
         for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index ac72348c186a..96151b2b91a2 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -46,7 +46,8 @@ void x509_free_certificate(struct x509_certificate *cert)
                 public_key_destroy(cert->pub);
                 kfree(cert->issuer);
                 kfree(cert->subject);
-                kfree(cert->fingerprint);
+                kfree(cert->id);
+                kfree(cert->skid);
                 kfree(cert->authority);
                 kfree(cert->sig.digest);
                 mpi_free(cert->sig.rsa.s);
@@ -62,6 +63,7 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
 {
         struct x509_certificate *cert;
         struct x509_parse_context *ctx;
+        struct asymmetric_key_id *kid;
         long ret;
 
         ret = -ENOMEM;
@@ -89,6 +91,17 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
         if (ret < 0)
                 goto error_decode;
 
+        /* Generate cert issuer + serial number key ID */
+        kid = asymmetric_key_generate_id(cert->raw_serial,
+                                         cert->raw_serial_size,
+                                         cert->raw_issuer,
+                                         cert->raw_issuer_size);
+        if (IS_ERR(kid)) {
+                ret = PTR_ERR(kid);
+                goto error_decode;
+        }
+        cert->id = kid;
+
         kfree(ctx);
         return cert;
 
@@ -407,36 +420,34 @@ int x509_process_extension(void *context, size_t hdrlen,
                            const void *value, size_t vlen)
 {
         struct x509_parse_context *ctx = context;
+        struct asymmetric_key_id *kid;
         const unsigned char *v = value;
-        char *f;
         int i;
 
         pr_debug("Extension: %u\n", ctx->last_oid);
 
         if (ctx->last_oid == OID_subjectKeyIdentifier) {
                 /* Get hold of the key fingerprint */
-                if (vlen < 3)
+                if (ctx->cert->skid || vlen < 3)
                         return -EBADMSG;
                 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
                         return -EBADMSG;
                 v += 2;
                 vlen -= 2;
 
-                f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
-                if (!f)
-                        return -ENOMEM;
-                for (i = 0; i < vlen; i++)
-                        sprintf(f + i * 2, "%02x", v[i]);
-                pr_debug("fingerprint %s\n", f);
-                ctx->cert->fingerprint = f;
+                kid = asymmetric_key_generate_id(v, vlen,
+                                                 ctx->cert->raw_subject,
+                                                 ctx->cert->raw_subject_size);
+                if (IS_ERR(kid))
+                        return PTR_ERR(kid);
+                ctx->cert->skid = kid;
+                pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
                 return 0;
         }
 
         if (ctx->last_oid == OID_authorityKeyIdentifier) {
-                size_t key_len;
-
                 /* Get hold of the CA key fingerprint */
-                if (vlen < 5)
+                if (ctx->cert->authority || vlen < 5)
                         return -EBADMSG;
 
                 /* Authority Key Identifier must be a Constructed SEQUENCE */
@@ -454,7 +465,7 @@ int x509_process_extension(void *context, size_t hdrlen,
                             v[3] > vlen - 4)
                                 return -EBADMSG;
 
-                        key_len = v[3];
+                        vlen = v[3];
                         v += 4;
                 } else {
                         /* Long Form length */
@@ -476,17 +487,17 @@ int x509_process_extension(void *context, size_t hdrlen,
                             v[sub + 1] > vlen - 4 - sub)
                                 return -EBADMSG;
 
-                        key_len = v[sub + 1];
+                        vlen = v[sub + 1];
                         v += (sub + 2);
                 }
 
-                f = kmalloc(key_len * 2 + 1, GFP_KERNEL);
-                if (!f)
-                        return -ENOMEM;
-                for (i = 0; i < key_len; i++)
-                        sprintf(f + i * 2, "%02x", v[i]);
-                pr_debug("authority   %s\n", f);
-                ctx->cert->authority = f;
+                kid = asymmetric_key_generate_id(v, vlen,
+                                                 ctx->cert->raw_issuer,
+                                                 ctx->cert->raw_issuer_size);
+                if (IS_ERR(kid))
+                        return PTR_ERR(kid);
+                pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+                ctx->cert->authority = kid;
                 return 0;
         }
 
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 1b76f207c1f3..0e8d59b010fb 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -19,8 +19,9 @@ struct x509_certificate {
         struct public_key_signature sig;        /* Signature parameters */
         char            *issuer;                /* Name of certificate issuer */
         char            *subject;               /* Name of certificate subject */
-        char            *fingerprint;           /* Key fingerprint as hex */
-        char            *authority;             /* Authority key fingerprint as hex */
+        struct asymmetric_key_id *id;           /* Issuer + serial number */
+        struct asymmetric_key_id *skid;         /* Subject key identifier */
+        struct asymmetric_key_id *authority;    /* Authority key identifier */
         struct tm       valid_from;
         struct tm       valid_to;
         const void      *tbs;                   /* Signed data */
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 "<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 @@ 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;