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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);
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