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authorDavid Howells <dhowells@redhat.com>2012-09-13 15:17:21 +0100
committerRusty Russell <rusty@rustcorp.com.au>2012-10-08 13:50:12 +1030
commit964f3b3bf49eb84b5831121446a28b76de3fb23a (patch)
tree7d299f690c8323c931b59bc142c45ac75097963f /crypto/asymmetric_keys/asymmetric_type.c
parent9a83b46578df149160b1da057656d2f0cfcbb5b6 (diff)
downloadlinux-stericsson-964f3b3bf49eb84b5831121446a28b76de3fb23a.tar.gz
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>
Diffstat (limited to 'crypto/asymmetric_keys/asymmetric_type.c')
-rw-r--r--crypto/asymmetric_keys/asymmetric_type.c156
1 files changed, 156 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
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+++ b/crypto/asymmetric_keys/asymmetric_type.c
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+/* Asymmetric public-key cryptography key type
+ *
+ * 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/seq_file.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "asymmetric_keys.h"
+
+MODULE_LICENSE("GPL");
+
+/*
+ * Match asymmetric keys on (part of) their name
+ * We have some shorthand methods for matching keys. We allow:
+ *
+ * "<desc>" - request a key by description
+ * "id:<id>" - request a key matching the ID
+ * "<subtype>:<id>" - request a key of a subtype
+ */
+static int asymmetric_key_match(const struct key *key, const void *description)
+{
+ const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
+ const char *spec = description;
+ const char *id, *kid;
+ ptrdiff_t speclen;
+ size_t idlen, kidlen;
+
+ 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++;
+
+ /* Anything after here requires a partial match on the ID string */
+ kid = asymmetric_key_id(key);
+ if (!kid)
+ return 0;
+
+ idlen = strlen(id);
+ kidlen = strlen(kid);
+ if (idlen > kidlen)
+ return 0;
+
+ kid += kidlen - idlen;
+ if (strcasecmp(id, kid) != 0)
+ return 0;
+
+ if (speclen == 2 &&
+ memcmp(spec, "id", 2) == 0)
+ return 1;
+
+ if (speclen == subtype->name_len &&
+ memcmp(spec, subtype->name, speclen) == 0)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * 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;
+
+ seq_puts(m, key->description);
+
+ if (subtype) {
+ seq_puts(m, ": ");
+ subtype->describe(key, m);
+
+ if (kid) {
+ seq_putc(m, ' ');
+ n = strlen(kid);
+ if (n <= 8)
+ seq_puts(m, kid);
+ else
+ seq_puts(m, kid + n - 8);
+ }
+
+ seq_puts(m, " [");
+ /* put something here to indicate the key's capabilities */
+ seq_putc(m, ']');
+ }
+}
+
+/*
+ * Instantiate a asymmetric_key defined key. The key was preparsed, so we just
+ * have to transfer the data here.
+ */
+static int asymmetric_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+ return -EOPNOTSUPP;
+}
+
+/*
+ * dispose of the data dangling from the corpse of a asymmetric key
+ */
+static void asymmetric_key_destroy(struct key *key)
+{
+ struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
+ 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;
+}
+
+struct key_type key_type_asymmetric = {
+ .name = "asymmetric",
+ .instantiate = asymmetric_key_instantiate,
+ .match = asymmetric_key_match,
+ .destroy = asymmetric_key_destroy,
+ .describe = asymmetric_key_describe,
+};
+EXPORT_SYMBOL_GPL(key_type_asymmetric);
+
+/*
+ * Module stuff
+ */
+static int __init asymmetric_key_init(void)
+{
+ return register_key_type(&key_type_asymmetric);
+}
+
+static void __exit asymmetric_key_cleanup(void)
+{
+ unregister_key_type(&key_type_asymmetric);
+}
+
+module_init(asymmetric_key_init);
+module_exit(asymmetric_key_cleanup);