[RFC PATCH 13/15] KEYS: Generalise x509_request_asymmetric_key()

[David Howells]

Generalise x509_request_asymmetric_key().  It doesn't really have any
dependencies on X.509 features as it uses generalised IDs and the
public_key structs that contain data extracted from X.509.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 crypto/asymmetric_keys/asymmetric_keys.h  |    2 +
 crypto/asymmetric_keys/pkcs7_trust.c      |   22 +++++------
 crypto/asymmetric_keys/public_key_trust.c |   60 +++++++++++++----------------
 include/crypto/public_key.h               |    8 ++--
 security/integrity/digsig_asymmetric.c    |    5 +-
 5 files changed, 46 insertions(+), 51 deletions(-)

diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h
index 1d450b580245..ca8e9ac34ce6 100644
--- a/crypto/asymmetric_keys/asymmetric_keys.h
+++ b/crypto/asymmetric_keys/asymmetric_keys.h
@@ -9,6 +9,8 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
+#include <keys/asymmetric-type.h>
+
 extern struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id);
 
 extern int __asymmetric_key_hex_to_key_id(const char *id,
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index 400ef359448a..8760bc566902 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -51,9 +51,9 @@ 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->id, x509->skid,
-						  false);
+		key = request_asymmetric_key(trust_keyring,
+					     x509->id, x509->skid,
+					     false);
 		if (!IS_ERR(key)) {
 			/* One of the X.509 certificates in the PKCS#7 message
 			 * is apparently the same as one we already trust.
@@ -84,10 +84,10 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 	 * trusted keys.
 	 */
 	if (last && (last->sig->auth_ids[0] || last->sig->auth_ids[1])) {
-		key = x509_request_asymmetric_key(trust_keyring,
-						  last->sig->auth_ids[0],
-						  last->sig->auth_ids[1],
-						  false);
+		key = request_asymmetric_key(trust_keyring,
+					     last->sig->auth_ids[0],
+					     last->sig->auth_ids[1],
+					     false);
 		if (!IS_ERR(key)) {
 			x509 = last;
 			pr_devel("sinfo %u: Root cert %u signer is key %x\n",
@@ -101,10 +101,10 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
 	/* 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->sig->auth_ids[0],
-					  NULL,
-					  false);
+	key = request_asymmetric_key(trust_keyring,
+				     sinfo->sig->auth_ids[0],
+				     NULL,
+				     false);
 	if (!IS_ERR(key)) {
 		pr_devel("sinfo %u: Direct signer is key %x\n",
 			 sinfo->index, key_serial(key));
diff --git a/crypto/asymmetric_keys/public_key_trust.c b/crypto/asymmetric_keys/public_key_trust.c
index 9febe612e659..afb2a3eb583a 100644
--- a/crypto/asymmetric_keys/public_key_trust.c
+++ b/crypto/asymmetric_keys/public_key_trust.c
@@ -1,6 +1,6 @@
-/* Instantiate a public key crypto key from an X.509 Certificate
+/* Validate one public key against another to determine trust chaining.
  *
- * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@xxxxxxxxxx)
  *
  * This program is free software; you can redistribute it and/or
@@ -9,17 +9,10 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
-#define pr_fmt(fmt) "X.509: "fmt
-#include <linux/module.h>
+#define pr_fmt(fmt) "PKEY: "fmt
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/err.h>
-#include <linux/mpi.h>
-#include <linux/asn1_decoder.h>
-#include <keys/asymmetric-subtype.h>
-#include <keys/asymmetric-parser.h>
-#include <keys/system_keyring.h>
-#include <crypto/hash.h>
 #include "asymmetric_keys.h"
 #include "public_key.h"
 #include "x509_parser.h"
@@ -63,21 +56,20 @@ __setup("ca_keys=", ca_keys_setup);
 #endif
 
 /**
- * x509_request_asymmetric_key - Request a key by X.509 certificate params.
+ * request_asymmetric_key - Request a key by ID.
  * @keyring: The keys to search.
- * @id: The issuer & serialNumber to look for or NULL.
- * @skid: The subjectKeyIdentifier to look for or NULL.
+ * @id_0: The first ID to look for or NULL.
+ * @id_1: The second ID to look for or NULL.
  * @partial: Use partial match if true, exact if false.
  *
  * Find a key in the given keyring by identifier.  The preferred identifier is
- * the issuer + serialNumber and the fallback identifier is the
- * subjectKeyIdentifier.  If both are given, the lookup is by the former, but
- * the latter must also match.
+ * the id_0 and the fallback identifier is the id_1.  If both are given, the
+ * lookup is by the former, but the latter must also match.
  */
-struct key *x509_request_asymmetric_key(struct key *keyring,
-					const struct asymmetric_key_id *id,
-					const struct asymmetric_key_id *skid,
-					bool partial)
+struct key *request_asymmetric_key(struct key *keyring,
+				   const struct asymmetric_key_id *id_0,
+				   const struct asymmetric_key_id *id_1,
+				   bool partial)
 {
 	struct key *key;
 	key_ref_t ref;
@@ -85,12 +77,12 @@ struct key *x509_request_asymmetric_key(struct key *keyring,
 	char *req, *p;
 	int len;
 
-	if (id) {
-		lookup = id->data;
-		len = id->len;
+	if (id_0) {
+		lookup = id_0->data;
+		len = id_0->len;
 	} else {
-		lookup = skid->data;
-		len = skid->len;
+		lookup = id_1->data;
+		len = id_1->len;
 	}
 
 	/* Construct an identifier "id:<keyid>". */
@@ -130,14 +122,15 @@ struct key *x509_request_asymmetric_key(struct key *keyring,
 	}
 
 	key = key_ref_to_ptr(ref);
-	if (id && skid) {
+	if (id_0 && id_1) {
 		const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
-		if (!kids->id[1]) {
-			pr_debug("issuer+serial match, but expected SKID missing\n");
+
+		if (!kids->id[0]) {
+			pr_debug("First ID matches, but second is missing\n");
 			goto reject;
 		}
-		if (!asymmetric_key_id_same(skid, kids->id[1])) {
-			pr_debug("issuer+serial match, but SKID does not\n");
+		if (!asymmetric_key_id_same(id_1, kids->id[1])) {
+			pr_debug("First ID matches, but second does not\n");
 			goto reject;
 		}
 	}
@@ -149,7 +142,7 @@ reject:
 	key_put(key);
 	return ERR_PTR(-EKEYREJECTED);
 }
-EXPORT_SYMBOL_GPL(x509_request_asymmetric_key);
+EXPORT_SYMBOL_GPL(request_asymmetric_key);
 
 /*
  * Check the new certificate against the ones in the trust keyring.  If one of
@@ -177,9 +170,8 @@ int x509_validate_trust(struct x509_certificate *cert,
 	if (cert->unsupported_sig)
 		return -ENOPKG;
 
-	key = x509_request_asymmetric_key(trust_keyring,
-					  sig->auth_ids[0], sig->auth_ids[1],
-					  false);
+	key = request_asymmetric_key(trust_keyring,
+				     sig->auth_ids[0], sig->auth_ids[1], false);
 	if (IS_ERR(key))
 		return PTR_ERR(key);
 
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index ed86bfb23e89..eaaf261d398a 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -102,9 +102,9 @@ extern int verify_signature(const struct key *key,
 			    const struct public_key_signature *sig);
 
 struct asymmetric_key_id;
-extern struct key *x509_request_asymmetric_key(struct key *keyring,
-					       const struct asymmetric_key_id *id,
-					       const struct asymmetric_key_id *skid,
-					       bool partial);
+extern struct key *request_asymmetric_key(struct key *keyring,
+					  const struct asymmetric_key_id *id_0,
+					  const struct asymmetric_key_id *id_1,
+					  bool partial);
 
 #endif /* _LINUX_PUBLIC_KEY_H */
diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index 5ade2a7517a6..be1af41b5c2a 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -24,7 +24,8 @@
 /*
  * Request an asymmetric key.
  */
-static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
+static struct key *ds_request_asymmetric_key(struct key *keyring,
+					     uint32_t keyid)
 {
 	struct key *key;
 	char name[12];
@@ -97,7 +98,7 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 	if (hdr->hash_algo >= PKEY_HASH__LAST)
 		return -ENOPKG;
 
-	key = request_asymmetric_key(keyring, __be32_to_cpu(hdr->keyid));
+	key = ds_request_asymmetric_key(keyring, __be32_to_cpu(hdr->keyid));
 	if (IS_ERR(key))
 		return PTR_ERR(key);