1 /* In-software asymmetric public-key crypto subtype
3 * See Documentation/crypto/asymmetric-keys.txt
5 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public Licence
10 * as published by the Free Software Foundation; either version
11 * 2 of the Licence, or (at your option) any later version.
14 #define pr_fmt(fmt) "PKEY: "fmt
15 #include <linux/module.h>
16 #include <linux/export.h>
17 #include <linux/kernel.h>
18 #include <linux/slab.h>
19 #include <linux/seq_file.h>
20 #include <linux/scatterlist.h>
21 #include <keys/asymmetric-subtype.h>
22 #include <crypto/public_key.h>
23 #include <crypto/akcipher.h>
25 MODULE_LICENSE("GPL");
28 * Provide a part of a description of the key for /proc/keys.
30 static void public_key_describe(const struct key *asymmetric_key,
33 struct public_key *key = asymmetric_key->payload.data[asym_crypto];
36 seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
40 * Destroy a public key algorithm key.
42 void public_key_free(struct public_key *key)
49 EXPORT_SYMBOL_GPL(public_key_free);
52 * Destroy a public key algorithm key.
54 static void public_key_destroy(void *payload0, void *payload3)
56 public_key_free(payload0);
57 public_key_signature_free(payload3);
60 struct public_key_completion {
61 struct completion completion;
65 static void public_key_verify_done(struct crypto_async_request *req, int err)
67 struct public_key_completion *compl = req->data;
69 if (err == -EINPROGRESS)
73 complete(&compl->completion);
77 * Verify a signature using a public key.
79 int public_key_verify_signature(const struct public_key *pkey,
80 const struct public_key_signature *sig)
82 struct public_key_completion compl;
83 struct crypto_akcipher *tfm;
84 struct akcipher_request *req;
85 struct scatterlist sig_sg, digest_sg;
87 char alg_name_buf[CRYPTO_MAX_ALG_NAME];
92 pr_devel("==>%s()\n", __func__);
101 alg_name = sig->pkey_algo;
102 if (strcmp(sig->pkey_algo, "rsa") == 0) {
103 /* The data wangled by the RSA algorithm is typically padded
104 * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
107 if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
108 "pkcs1pad(rsa,%s)", sig->hash_algo
109 ) >= CRYPTO_MAX_ALG_NAME)
111 alg_name = alg_name_buf;
114 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
118 req = akcipher_request_alloc(tfm, GFP_KERNEL);
122 ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
126 outlen = crypto_akcipher_maxsize(tfm);
127 output = kmalloc(outlen, GFP_KERNEL);
131 sg_init_one(&sig_sg, sig->s, sig->s_size);
132 sg_init_one(&digest_sg, output, outlen);
133 akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
135 init_completion(&compl.completion);
136 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
137 CRYPTO_TFM_REQ_MAY_SLEEP,
138 public_key_verify_done, &compl);
140 /* Perform the verification calculation. This doesn't actually do the
141 * verification, but rather calculates the hash expected by the
142 * signature and returns that to us.
144 ret = crypto_akcipher_verify(req);
145 if ((ret == -EINPROGRESS) || (ret == -EBUSY)) {
146 wait_for_completion(&compl.completion);
150 goto out_free_output;
152 /* Do the actual verification step. */
153 if (req->dst_len != sig->digest_size ||
154 memcmp(sig->digest, output, sig->digest_size) != 0)
160 akcipher_request_free(req);
162 crypto_free_akcipher(tfm);
163 pr_devel("<==%s() = %d\n", __func__, ret);
166 EXPORT_SYMBOL_GPL(public_key_verify_signature);
168 static int public_key_verify_signature_2(const struct key *key,
169 const struct public_key_signature *sig)
171 const struct public_key *pk = key->payload.data[asym_crypto];
172 return public_key_verify_signature(pk, sig);
176 * Public key algorithm asymmetric key subtype
178 struct asymmetric_key_subtype public_key_subtype = {
179 .owner = THIS_MODULE,
180 .name = "public_key",
181 .name_len = sizeof("public_key") - 1,
182 .describe = public_key_describe,
183 .destroy = public_key_destroy,
184 .verify_signature = public_key_verify_signature_2,
186 EXPORT_SYMBOL_GPL(public_key_subtype);