KEYS: Implement asymmetric key type

Create a key type that can be used to represent an asymmetric key type for use
in appropriate cryptographic operations, such as encryption, decryption,
signature generation and signature verification.

The key type is "asymmetric" and can provide access to a variety of
cryptographic algorithms.

Possibly, this would be better as "public_key" - but that has the disadvantage
that "public key" is an overloaded term.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 80 insertions, 0 deletions

diff --git a/include/keys/asymmetric-subtype.h b/include/keys/asymmetric-subtype.h
new file mode 100644
index 0000000..4b840e8
--- /dev/null
+++ b/include/keys/asymmetric-subtype.h
@@ -0,0 +1,55 @@
+/* Asymmetric public-key cryptography key subtype
+ *
+ * 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.
+ */
+
+#ifndef _KEYS_ASYMMETRIC_SUBTYPE_H
+#define _KEYS_ASYMMETRIC_SUBTYPE_H
+
+#include <linux/seq_file.h>
+#include <keys/asymmetric-type.h>
+
+struct public_key_signature;
+
+/*
+ * Keys of this type declare a subtype that indicates the handlers and
+ * capabilities.
+ */
+struct asymmetric_key_subtype {
+	struct module		*owner;
+	const char		*name;
+	unsigned short		name_len;	/* length of name */
+
+	/* Describe a key of this subtype for /proc/keys */
+	void (*describe)(const struct key *key, struct seq_file *m);
+
+	/* Destroy a key of this subtype */
+	void (*destroy)(void *payload);
+
+	/* Verify the signature on a key of this subtype (optional) */
+	int (*verify_signature)(const struct key *key,
+				const struct public_key_signature *sig);
+};
+
+/**
+ * asymmetric_key_subtype - Get the subtype from an asymmetric key
+ * @key: The key of interest.
+ *
+ * Retrieves and returns the subtype pointer of the asymmetric key from the
+ * type-specific data attached to the key.
+ */
+static inline
+struct asymmetric_key_subtype *asymmetric_key_subtype(const struct key *key)
+{
+	return key->type_data.p[0];
+}
+
+#endif /* _KEYS_ASYMMETRIC_SUBTYPE_H */
diff --git a/include/keys/asymmetric-type.h b/include/keys/asymmetric-type.h
new file mode 100644
index 0000000..7dd4734
--- /dev/null
+++ b/include/keys/asymmetric-type.h
@@ -0,0 +1,25 @@
+/* Asymmetric Public-key cryptography key type interface
+ *
+ * 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.
+ */
+
+#ifndef _KEYS_ASYMMETRIC_TYPE_H
+#define _KEYS_ASYMMETRIC_TYPE_H
+
+#include <linux/key-type.h>
+
+extern struct key_type key_type_asymmetric;
+
+/*
+ * The payload is at the discretion of the subtype.
+ */
+
+#endif /* _KEYS_ASYMMETRIC_TYPE_H */