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_DESCRIPTION("In-software asymmetric public-key subtype");
26 MODULE_AUTHOR("Red Hat, Inc.");
27 MODULE_LICENSE("GPL");
30 * Provide a part of a description of the key for /proc/keys.
32 static void public_key_describe(const struct key *asymmetric_key,
35 struct public_key *key = asymmetric_key->payload.data[asym_crypto];
38 seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);
42 * Destroy a public key algorithm key.
44 void public_key_free(struct public_key *key)
51 EXPORT_SYMBOL_GPL(public_key_free);
54 * Destroy a public key algorithm key.
56 static void public_key_destroy(void *payload0, void *payload3)
58 public_key_free(payload0);
59 public_key_signature_free(payload3);
63 * Verify a signature using a public key.
65 int public_key_verify_signature(const struct public_key *pkey,
66 const struct public_key_signature *sig)
68 struct crypto_wait cwait;
69 struct crypto_akcipher *tfm;
70 struct akcipher_request *req;
71 struct scatterlist sig_sg, digest_sg;
73 char alg_name_buf[CRYPTO_MAX_ALG_NAME];
78 pr_devel("==>%s()\n", __func__);
85 alg_name = sig->pkey_algo;
86 if (strcmp(sig->pkey_algo, "rsa") == 0) {
87 /* The data wangled by the RSA algorithm is typically padded
88 * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
91 if (snprintf(alg_name_buf, CRYPTO_MAX_ALG_NAME,
92 "pkcs1pad(rsa,%s)", sig->hash_algo
93 ) >= CRYPTO_MAX_ALG_NAME)
95 alg_name = alg_name_buf;
98 tfm = crypto_alloc_akcipher(alg_name, 0, 0);
102 req = akcipher_request_alloc(tfm, GFP_KERNEL);
106 ret = crypto_akcipher_set_pub_key(tfm, pkey->key, pkey->keylen);
111 outlen = crypto_akcipher_maxsize(tfm);
112 output = kmalloc(outlen, GFP_KERNEL);
116 sg_init_one(&sig_sg, sig->s, sig->s_size);
117 sg_init_one(&digest_sg, output, outlen);
118 akcipher_request_set_crypt(req, &sig_sg, &digest_sg, sig->s_size,
120 crypto_init_wait(&cwait);
121 akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
122 CRYPTO_TFM_REQ_MAY_SLEEP,
123 crypto_req_done, &cwait);
125 /* Perform the verification calculation. This doesn't actually do the
126 * verification, but rather calculates the hash expected by the
127 * signature and returns that to us.
129 ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
131 goto out_free_output;
133 /* Do the actual verification step. */
134 if (req->dst_len != sig->digest_size ||
135 memcmp(sig->digest, output, sig->digest_size) != 0)
141 akcipher_request_free(req);
143 crypto_free_akcipher(tfm);
144 pr_devel("<==%s() = %d\n", __func__, ret);
147 EXPORT_SYMBOL_GPL(public_key_verify_signature);
149 static int public_key_verify_signature_2(const struct key *key,
150 const struct public_key_signature *sig)
152 const struct public_key *pk = key->payload.data[asym_crypto];
153 return public_key_verify_signature(pk, sig);
157 * Public key algorithm asymmetric key subtype
159 struct asymmetric_key_subtype public_key_subtype = {
160 .owner = THIS_MODULE,
161 .name = "public_key",
162 .name_len = sizeof("public_key") - 1,
163 .describe = public_key_describe,
164 .destroy = public_key_destroy,
165 .verify_signature = public_key_verify_signature_2,
167 EXPORT_SYMBOL_GPL(public_key_subtype);