KEYS: Allow authentication data to be stored in an asymmetric key

Allow authentication data to be stored in an asymmetric key in the 4th
element of the key payload and provide a way for it to be destroyed.

For the public key subtype, this will be a public_key_signature struct.
Signed-off-by: David Howells <dhowells@redhat.com>

crypto/asymmetric_keys/asymmetric_type.c

@@ -331,7 +331,8 @@ static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep)
 	pr_devel("==>%s()\n", __func__);
 
 	if (subtype) {
-		subtype->destroy(prep->payload.data[asym_crypto]);
+		subtype->destroy(prep->payload.data[asym_crypto],
+				 prep->payload.data[asym_auth]);
 		module_put(subtype->owner);
 	}
 	asymmetric_key_free_kids(kids);
@@ -346,13 +347,15 @@ static void asymmetric_key_destroy(struct key *key)
 	struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
 	struct asymmetric_key_ids *kids = key->payload.data[asym_key_ids];
 	void *data = key->payload.data[asym_crypto];
+	void *auth = key->payload.data[asym_auth];
 
 	key->payload.data[asym_crypto] = NULL;
 	key->payload.data[asym_subtype] = NULL;
 	key->payload.data[asym_key_ids] = NULL;
+	key->payload.data[asym_auth] = NULL;
 
 	if (subtype) {
-		subtype->destroy(data);
+		subtype->destroy(data, auth);
 		module_put(subtype->owner);
 	}
 

crypto/asymmetric_keys/public_key.c

@@ -39,15 +39,23 @@ static void public_key_describe(const struct key *asymmetric_key,
 /*
  * Destroy a public key algorithm key.
  */
-void public_key_destroy(void *payload)
+void public_key_free(struct public_key *key)
 {
-	struct public_key *key = payload;
-
-	if (key)
+	if (key) {
 		kfree(key->key);
-	kfree(key);
+		kfree(key);
+	}
+}
+EXPORT_SYMBOL_GPL(public_key_free);
+
+/*
+ * Destroy a public key algorithm key.
+ */
+static void public_key_destroy(void *payload0, void *payload3)
+{
+	public_key_free(payload0);
+	public_key_signature_free(payload3);
 }
-EXPORT_SYMBOL_GPL(public_key_destroy);
 
 struct public_key_completion {
 	struct completion completion;

crypto/asymmetric_keys/signature.c

@@ -15,9 +15,23 @@
 #include <keys/asymmetric-subtype.h>
 #include <linux/export.h>
 #include <linux/err.h>
+#include <linux/slab.h>
 #include <crypto/public_key.h>
 #include "asymmetric_keys.h"
 
+/*
+ * Destroy a public key signature.
+ */
+void public_key_signature_free(struct public_key_signature *sig)
+{
+	if (sig) {
+		kfree(sig->s);
+		kfree(sig->digest);
+		kfree(sig);
+	}
+}
+EXPORT_SYMBOL_GPL(public_key_signature_free);
+
 /**
  * verify_signature - Initiate the use of an asymmetric key to verify a signature
  * @key: The asymmetric key to verify against

crypto/asymmetric_keys/x509_cert_parser.c

@@ -47,7 +47,7 @@ struct x509_parse_context {
 void x509_free_certificate(struct x509_certificate *cert)
 {
 	if (cert) {
-		public_key_destroy(cert->pub);
+		public_key_free(cert->pub);
 		kfree(cert->issuer);
 		kfree(cert->subject);
 		kfree(cert->id);

include/crypto/public_key.h

@@ -41,7 +41,7 @@ struct public_key {
 	const char *pkey_algo;
 };
 
-extern void public_key_destroy(void *payload);
+extern void public_key_free(struct public_key *key);
 
 /*
  * Public key cryptography signature data
@@ -55,7 +55,10 @@ struct public_key_signature {
 	const char *hash_algo;
 };
 
+extern void public_key_signature_free(struct public_key_signature *sig);
+
 extern struct asymmetric_key_subtype public_key_subtype;
+
 struct key;
 extern int verify_signature(const struct key *key,
 			    const struct public_key_signature *sig);

include/keys/asymmetric-subtype.h

@@ -32,7 +32,7 @@ struct asymmetric_key_subtype {
 	void (*describe)(const struct key *key, struct seq_file *m);
 
 	/* Destroy a key of this subtype */
-	void (*destroy)(void *payload);
+	void (*destroy)(void *payload_crypto, void *payload_auth);
 
 	/* Verify the signature on a key of this subtype (optional) */
 	int (*verify_signature)(const struct key *key,

include/keys/asymmetric-type.h

@@ -23,9 +23,10 @@ extern struct key_type key_type_asymmetric;
  * follows:
  */
 enum asymmetric_payload_bits {
-	asym_crypto,
-	asym_subtype,
-	asym_key_ids,
+	asym_crypto,		/* The data representing the key */
+	asym_subtype,		/* Pointer to an asymmetric_key_subtype struct */
+	asym_key_ids,		/* Pointer to an asymmetric_key_ids struct */
+	asym_auth		/* The key's authorisation (signature, parent key ID) */
 };
 
 /*