3 files changed, 54 insertions, 1 deletions

diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 5ed46eecb299..8dcdf0cdb261 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -4,6 +4,6 @@
 
 obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += asymmetric_keys.o
 
-asymmetric_keys-y := asymmetric_type.o
+asymmetric_keys-y := asymmetric_type.o signature.o
 
 obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
diff --git a/crypto/asymmetric_keys/signature.c b/crypto/asymmetric_keys/signature.c
new file mode 100644
index 000000000000..50b3f880b4ff
--- /dev/null
+++ b/crypto/asymmetric_keys/signature.c
@@ -0,0 +1,49 @@
+/* Signature verification with an asymmetric key
+ *
+ * See Documentation/security/asymmetric-keys.txt
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <keys/asymmetric-subtype.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <crypto/public_key.h>
+#include "asymmetric_keys.h"
+
+/**
+ * verify_signature - Initiate the use of an asymmetric key to verify a signature
+ * @key: The asymmetric key to verify against
+ * @sig: The signature to check
+ *
+ * Returns 0 if successful or else an error.
+ */
+int verify_signature(const struct key *key,
+                     const struct public_key_signature *sig)
+{
+        const struct asymmetric_key_subtype *subtype;
+        int ret;
+
+        pr_devel("==>%s()\n", __func__);
+
+        if (key->type != &key_type_asymmetric)
+                return -EINVAL;
+        subtype = asymmetric_key_subtype(key);
+        if (!subtype ||
+            !key->payload.data)
+                return -EINVAL;
+        if (!subtype->verify_signature)
+                return -ENOTSUPP;
+
+        ret = subtype->verify_signature(key, sig);
+
+        pr_devel("<==%s() = %d\n", __func__, ret);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(verify_signature);
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 4b8b6c16eac6..f5b0224c9967 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -101,4 +101,8 @@ struct public_key_signature {
         };
 };
 
+struct key;
+extern int verify_signature(const struct key *key,
+                            const struct public_key_signature *sig);
+
 #endif /* _LINUX_PUBLIC_KEY_H */