Merge tag 'keys-pkcs7-20140916' into keys-next

Changes for next to improve the matching of asymmetric keys and to improve the
handling of PKCS#7 certificates:

 (1) Provide a method to preparse the data supplied for matching a key.  This
     permits they key type to extract out the bits it needs for matching once
     only.

     Further, the type of search (direct lookup or iterative) can be set and
     the function used to actually check the match can be set by preparse
     rather than being hard coded for the type.

 (2) Improves asymmetric keys identification.

     Keys derived from X.509 certs now get labelled with IDs derived from their
     issuer and certificate number (required to match PKCS#7) and from their
     SKID and subject (required to match X.509).

     IDs are now binary and match criterion preparsing is provided so that
     criteria can be turned into binary blobs to make matching faster.

 (3) Improves PKCS#7 message handling to permit PKCS#7 messages without X.509
     cert lists to be matched to trusted keys, thereby allowing minimally sized
     PKCS#7 certs to be used.

 (4) Improves PKCS#7 message handling to better handle certificate chains that
     are broken due to unsupported crypto that can otherwise by used to
     intersect a trust keyring.

These must go on top of the PKCS#7 parser cleanup fixes.

Signed-off-by: David Howells <dhowells@redhat.com>

10 files changed, 420 insertions, 202 deletions

diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h
index a63c551c6557..fd21ac28e0a0 100644
--- a/crypto/asymmetric_keys/asymmetric_keys.h
+++ b/crypto/asymmetric_keys/asymmetric_keys.h
@@ -9,9 +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);
 
-static inline const char *asymmetric_key_id(const struct key *key)
+extern struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id);
+
+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 eb8cd46961a5..718e779a010e 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -15,6 +15,7 @@
 #include <linux/seq_file.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/ctype.h>
 #include "asymmetric_keys.h"
 
 MODULE_LICENSE("GPL");
@@ -22,85 +23,165 @@ MODULE_LICENSE("GPL");
 static LIST_HEAD(asymmetric_key_parsers);
 static DECLARE_RWSEM(asymmetric_key_parsers_sem);
 
-/*
- * Match asymmetric key id with partial match
- * @id:		key id to match in a form "id:<id>"
+/**
+ * asymmetric_key_generate_id: Construct an asymmetric key ID
+ * @val_1: First binary blob
+ * @len_1: Length of first binary blob
+ * @val_2: Second binary blob
+ * @len_2: Length of second binary blob
+ *
+ * Construct an asymmetric key ID from a pair of binary blobs.
  */
-int asymmetric_keyid_match(const char *kid, const char *id)
+struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
+						     size_t len_1,
+						     const void *val_2,
+						     size_t len_2)
 {
-	size_t idlen, kidlen;
+	struct asymmetric_key_id *kid;
+
+	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
+		      GFP_KERNEL);
+	if (!kid)
+		return ERR_PTR(-ENOMEM);
+	kid->len = len_1 + len_2;
+	memcpy(kid->data, val_1, len_1);
+	memcpy(kid->data + len_1, val_2, len_2);
+	return kid;
+}
+EXPORT_SYMBOL_GPL(asymmetric_key_generate_id);
 
-	if (!kid || !id)
-		return 0;
+/**
+ * asymmetric_key_id_same - Return true if two asymmetric keys IDs are the same.
+ * @kid_1, @kid_2: The key IDs to compare
+ */
+bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
+			    const struct asymmetric_key_id *kid2)
+{
+	if (!kid1 || !kid2)
+		return false;
+	if (kid1->len != kid2->len)
+		return false;
+	return memcmp(kid1->data, kid2->data, kid1->len) == 0;
+}
+EXPORT_SYMBOL_GPL(asymmetric_key_id_same);
 
-	/* make it possible to use id as in the request: "id:<id>" */
-	if (strncmp(id, "id:", 3) == 0)
-		id += 3;
+/**
+ * asymmetric_match_key_ids - Search asymmetric key IDs
+ * @kids: The list of key IDs to check
+ * @match_id: The key ID we're looking for
+ */
+bool asymmetric_match_key_ids(const struct asymmetric_key_ids *kids,
+			      const struct asymmetric_key_id *match_id)
+{
+	if (!kids || !match_id)
+		return false;
+	if (asymmetric_key_id_same(kids->id[0], match_id))
+		return true;
+	if (asymmetric_key_id_same(kids->id[1], match_id))
+		return true;
+	return false;
+}
+EXPORT_SYMBOL_GPL(asymmetric_match_key_ids);
 
-	/* Anything after here requires a partial match on the ID string */
-	idlen = strlen(id);
-	kidlen = strlen(kid);
-	if (idlen > kidlen)
-		return 0;
+/**
+ * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
+ * @id: The ID as a hex string.
+ */
+struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
+{
+	struct asymmetric_key_id *match_id;
+	const char *p;
+	ptrdiff_t hexlen;
+
+	if (!*id)
+		return ERR_PTR(-EINVAL);
+	for (p = id; *p; p++)
+		if (!isxdigit(*p))
+			return ERR_PTR(-EINVAL);
+	hexlen = p - id;
+	if (hexlen & 1)
+		return ERR_PTR(-EINVAL);
+
+	match_id = kmalloc(sizeof(struct asymmetric_key_id) + hexlen / 2,
+			   GFP_KERNEL);
+	if (!match_id)
+		return ERR_PTR(-ENOMEM);
+	match_id->len = hexlen / 2;
+	(void)hex2bin(match_id->data, id, hexlen / 2);
+	return match_id;
+}
 
-	kid += kidlen - idlen;
-	if (strcasecmp(id, kid) != 0)
-		return 0;
+/*
+ * 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_ids *kids = asymmetric_key_ids(key);
+	const struct asymmetric_key_id *match_id = match_data->preparsed;
 
-	return 1;
+	return asymmetric_match_key_ids(kids, match_id);
 }
-EXPORT_SYMBOL_GPL(asymmetric_keyid_match);
 
 /*
- * Match asymmetric keys on (part of) their name
- * We have some shorthand methods for matching keys.  We allow:
+ * Preparse the match criterion.  If we don't set lookup_type and cmp,
+ * the default will be an exact match on the key description.
  *
- *	"<desc>"	- request a key by description
- *	"id:<id>"	- request a key matching the ID
- *	"<subtype>:<id>" - request a key of a subtype
+ * There are some specifiers for matching key IDs rather than by the key
+ * description:
+ *
+ *	"id:<id>" - request a key by any available ID
+ *
+ * These have to be searched by iteration rather than by direct lookup because
+ * the key is hashed according to its description.
  */
-static int asymmetric_key_match(const struct key *key, const void *description)
+static int asymmetric_key_match_preparse(struct key_match_data *match_data)
 {
-	const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
-	const char *spec = description;
+	struct asymmetric_key_id *match_id;
+	const char *spec = match_data->raw_data;
 	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 (!spec || !*spec)
+		return -EINVAL;
+	if (spec[0] == 'i' &&
+	    spec[1] == 'd' &&
+	    spec[2] == ':') {
+		id = spec + 3;
+	} else {
+		goto default_match;
+	}
 
-	if (speclen == 2 && memcmp(spec, "id", 2) == 0)
-		return asymmetric_keyid_match(asymmetric_key_id(key), id);
+	match_id = asymmetric_key_hex_to_key_id(id);
+	if (!match_id)
+		return -ENOMEM;
 
-	if (speclen == subtype->name_len &&
-	    memcmp(spec, subtype->name, speclen) == 0)
-		return 1;
+	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;
 }
 
 /*
+ * Free the preparsed the match criterion.
+ */
+static void asymmetric_key_match_free(struct key_match_data *match_data)
+{
+	kfree(match_data->preparsed);
+}
+
+/*
  * Describe the asymmetric key
  */
 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);
 
@@ -108,13 +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, " [");
@@ -165,6 +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__);
 
@@ -172,7 +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);
 }
 
@@ -182,13 +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 = {
@@ -196,10 +292,10 @@ struct key_type key_type_asymmetric = {
 	.preparse	= asymmetric_key_preparse,
 	.free_preparse	= asymmetric_key_free_preparse,
 	.instantiate	= generic_key_instantiate,
-	.match		= asymmetric_key_match,
+	.match_preparse	= asymmetric_key_match_preparse,
+	.match_free	= asymmetric_key_match_free,
 	.destroy	= asymmetric_key_destroy,
 	.describe	= asymmetric_key_describe,
-	.def_lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE,
 };
 EXPORT_SYMBOL_GPL(key_type_asymmetric);
 
diff --git a/crypto/asymmetric_keys/pkcs7_key_type.c b/crypto/asymmetric_keys/pkcs7_key_type.c
index 3de5fb011de0..751f8fd7335d 100644
--- a/crypto/asymmetric_keys/pkcs7_key_type.c
+++ b/crypto/asymmetric_keys/pkcs7_key_type.c
@@ -72,11 +72,9 @@ error:
  */
 static struct key_type key_type_pkcs7 = {
 	.name			= "pkcs7_test",
-	.def_lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
 	.preparse		= pkcs7_preparse,
 	.free_preparse		= user_free_preparse,
 	.instantiate		= generic_key_instantiate,
-	.match			= user_match,
 	.revoke			= user_revoke,
 	.destroy		= user_destroy,
 	.describe		= user_describe,
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..efc7dc9b8f9c 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.h
+++ b/crypto/asymmetric_keys/pkcs7_parser.h
@@ -23,6 +23,7 @@ struct pkcs7_signed_info {
 	struct x509_certificate *signer; /* Signing certificate (in msg->certs) */
 	unsigned index;
 	bool trusted;
+	bool unsupported_crypto;	/* T if not usable due to missing crypto */
 
 	/* Message digest - the digest of the Content Data (or NULL) */
 	const void	*msgdigest;
@@ -33,10 +34,7 @@ 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..ae47be6128c4 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -35,6 +35,11 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 
 	kenter(",%u,", sinfo->index);
 
+	if (sinfo->unsupported_crypto) {
+		kleave(" = -ENOPKG [cached]");
+		return -ENOPKG;
+	}
+
 	for (x509 = sinfo->signer; x509; x509 = x509->signer) {
 		if (x509->seen) {
 			if (x509->verified) {
@@ -49,15 +54,17 @@ 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);
-		if (!IS_ERR(key))
+		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.
 			 * Verify that the trusted variant can also validate
 			 * the signature on the descendant.
 			 */
+			pr_devel("sinfo %u: Cert %u as key %x\n",
+				 sinfo->index, x509->index, key_serial(key));
 			goto matched;
+		}
 		if (key == ERR_PTR(-ENOMEM))
 			return -ENOMEM;
 
@@ -77,16 +84,34 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 	/* No match - see if the root certificate has a signer amongst the
 	 * trusted keys.
 	 */
-	if (!last || !last->issuer || !last->authority) {
-		kleave(" = -ENOKEY [no backref]");
-		return -ENOKEY;
+	if (last && last->authority) {
+		key = x509_request_asymmetric_key(trust_keyring, last->authority);
+		if (!IS_ERR(key)) {
+			x509 = last;
+			pr_devel("sinfo %u: Root cert %u signer is key %x\n",
+				 sinfo->index, x509->index, key_serial(key));
+			goto matched;
+		}
+		if (PTR_ERR(key) != -ENOKEY)
+			return PTR_ERR(key);
+	}
+
+	/* As a last resort, see if we have a trusted public key that matches
+	 * the signed info directly.
+	 */
+	key = x509_request_asymmetric_key(trust_keyring,
+					  sinfo->signing_cert_id);
+	if (!IS_ERR(key)) {
+		pr_devel("sinfo %u: Direct signer is key %x\n",
+			 sinfo->index, key_serial(key));
+		x509 = NULL;
+		goto matched;
 	}
+	if (PTR_ERR(key) != -ENOKEY)
+		return PTR_ERR(key);
 
-	key = x509_request_asymmetric_key(trust_keyring, last->issuer,
-					  last->authority);
-	if (IS_ERR(key))
-		return PTR_ERR(key) == -ENOMEM ? -ENOMEM : -ENOKEY;
-	x509 = last;
+	kleave(" = -ENOKEY [no backref]");
+	return -ENOKEY;
 
 matched:
 	ret = verify_signature(key, sig);
@@ -100,10 +125,12 @@ matched:
 	}
 
 verified:
-	x509->verified = true;
-	for (p = sinfo->signer; p != x509; p = p->signer) {
-		p->verified = true;
-		p->trusted = trusted;
+	if (x509) {
+		x509->verified = true;
+		for (p = sinfo->signer; p != x509; p = p->signer) {
+			p->verified = true;
+			p->trusted = trusted;
+		}
 	}
 	sinfo->trusted = trusted;
 	kleave(" = 0");
@@ -141,24 +168,28 @@ int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
 {
 	struct pkcs7_signed_info *sinfo;
 	struct x509_certificate *p;
-	int cached_ret = 0, ret;
+	int cached_ret = -ENOKEY;
+	int ret;
 
 	for (p = pkcs7->certs; p; p = p->next)
 		p->seen = false;
 
 	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
 		ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring);
-		if (ret < 0) {
-			if (ret == -ENOPKG) {
+		switch (ret) {
+		case -ENOKEY:
+			continue;
+		case -ENOPKG:
+			if (cached_ret == -ENOKEY)
 				cached_ret = -ENOPKG;
-			} else if (ret == -ENOKEY) {
-				if (cached_ret == 0)
-					cached_ret = -ENOKEY;
-			} else {
-				return ret;
-			}
+			continue;
+		case 0:
+			*_trusted |= sinfo->trusted;
+			cached_ret = 0;
+			continue;
+		default:
+			return ret;
 		}
-		*_trusted |= sinfo->trusted;
 	}
 
 	return cached_ret;
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index c62cf8006e1f..cd455450b069 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);
@@ -164,9 +153,14 @@ 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);
-	return -ENOKEY;
+
+	/* The relevant X.509 cert isn't found here, but it might be found in
+	 * the trust keyring.
+	 */
+	pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
+		 sinfo->index,
+		 sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
+	return 0;
 }
 
 /*
@@ -184,15 +178,18 @@ 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)
-			return ret;
+			goto maybe_missing_crypto_in_x509;
 
 		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) {
@@ -209,7 +206,7 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 
 			ret = x509_check_signature(x509->pub, x509);
 			if (ret < 0)
-				return ret;
+				goto maybe_missing_crypto_in_x509;
 			x509->signer = x509;
 			pr_debug("- self-signed\n");
 			return 0;
@@ -218,13 +215,14 @@ 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 +231,7 @@ 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);
@@ -250,6 +248,17 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		x509 = p;
 		might_sleep();
 	}
+
+maybe_missing_crypto_in_x509:
+	/* Just prune the certificate chain at this point if we lack some
+	 * crypto module to go further.  Note, however, we don't want to set
+	 * sinfo->missing_crypto as the signed info block may still be
+	 * validatable against an X.509 cert lower in the chain that we have a
+	 * trusted copy of.
+	 */
+	if (ret == -ENOPKG)
+		return 0;
+	return ret;
 }
 
 /*
@@ -269,11 +278,14 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
 	if (ret < 0)
 		return ret;
 
-	/* Find the key for the signature */
+	/* Find the key for the signature if there is one */
 	ret = pkcs7_find_key(pkcs7, sinfo);
 	if (ret < 0)
 		return ret;
 
+	if (!sinfo->signer)
+		return 0;
+
 	pr_devel("Using X.509[%u] for sig %u\n",
 		 sinfo->signer->index, sinfo->index);
 
@@ -291,11 +303,33 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
 /**
  * pkcs7_verify - Verify a PKCS#7 message
  * @pkcs7: The PKCS#7 message to be verified
+ *
+ * Verify a PKCS#7 message is internally consistent - that is, the data digest
+ * matches the digest in the AuthAttrs and any signature in the message or one
+ * of the X.509 certificates it carries that matches another X.509 cert in the
+ * message can be verified.
+ *
+ * This does not look to match the contents of the PKCS#7 message against any
+ * external public keys.
+ *
+ * Returns, in order of descending priority:
+ *
+ *  (*) -EKEYREJECTED if a signature failed to match for which we found an
+ *	appropriate X.509 certificate, or:
+ *
+ *  (*) -EBADMSG if some part of the message was invalid, or:
+ *
+ *  (*) -ENOPKG if none of the signature chains are verifiable because suitable
+ *	crypto modules couldn't be found, or:
+ *
+ *  (*) 0 if all the signature chains that don't incur -ENOPKG can be verified
+ *	(note that a signature chain may be of zero length), or:
  */
 int pkcs7_verify(struct pkcs7_message *pkcs7)
 {
 	struct pkcs7_signed_info *sinfo;
 	struct x509_certificate *x509;
+	int enopkg = -ENOPKG;
 	int ret, n;
 
 	kenter("");
@@ -304,18 +338,24 @@ 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) {
 		ret = pkcs7_verify_one(pkcs7, sinfo);
 		if (ret < 0) {
+			if (ret == -ENOPKG) {
+				sinfo->unsupported_crypto = true;
+				continue;
+			}
 			kleave(" = %d", ret);
 			return ret;
 		}
+		enopkg = 0;
 	}
 
-	kleave(" = 0");
-	return 0;
+	kleave(" = %d", enopkg);
+	return enopkg;
 }
 EXPORT_SYMBOL_GPL(pkcs7_verify);
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..4e1a384901ed 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 */
@@ -37,6 +38,7 @@ struct x509_certificate {
 	bool		seen;			/* Infinite recursion prevention */
 	bool		verified;
 	bool		trusted;
+	bool		unsupported_crypto;	/* T if can't be verified due to missing crypto */
 };
 
 /*
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index f3d62307e6ee..1d9a4c555376 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);
 
@@ -112,6 +115,8 @@ int x509_get_sig_params(struct x509_certificate *cert)
 
 	pr_devel("==>%s()\n", __func__);
 
+	if (cert->unsupported_crypto)
+		return -ENOPKG;
 	if (cert->sig.rsa.s)
 		return 0;
 
@@ -124,8 +129,13 @@ int x509_get_sig_params(struct x509_certificate *cert)
 	 * big the hash operational data will be.
 	 */
 	tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0);
-	if (IS_ERR(tfm))
-		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
+	if (IS_ERR(tfm)) {
+		if (PTR_ERR(tfm) == -ENOENT) {
+			cert->unsupported_crypto = true;
+			return -ENOPKG;
+		}
+		return PTR_ERR(tfm);
+	}
 
 	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 	digest_size = crypto_shash_digestsize(tfm);
@@ -172,6 +182,8 @@ int x509_check_signature(const struct public_key *pub,
 		return ret;
 
 	ret = public_key_verify_signature(pub, &cert->sig);
+	if (ret == -ENOPKG)
+		cert->unsupported_crypto = true;
 	pr_debug("Cert Verification: %d\n", ret);
 	return ret;
 }
@@ -195,11 +207,10 @@ 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 +225,11 @@ 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 +262,12 @@ 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 +279,47 @@ 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;