perf stat: Fix indentation of stalled backend cycle
[linux/fpc-iii.git] / lib / digsig.c
blob07be6c1ef4e2564c321b7bda1669fc1e9d84f8cf
1 /*
2 * Copyright (C) 2011 Nokia Corporation
3 * Copyright (C) 2011 Intel Corporation
5 * Author:
6 * Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
7 * <dmitry.kasatkin@intel.com>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, version 2 of the License.
13 * File: sign.c
14 * implements signature (RSA) verification
15 * pkcs decoding is based on LibTomCrypt code
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/err.h>
21 #include <linux/module.h>
22 #include <linux/slab.h>
23 #include <linux/key.h>
24 #include <linux/crypto.h>
25 #include <crypto/hash.h>
26 #include <crypto/sha.h>
27 #include <keys/user-type.h>
28 #include <linux/mpi.h>
29 #include <linux/digsig.h>
31 static struct crypto_shash *shash;
33 static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
34 unsigned long msglen,
35 unsigned long modulus_bitlen,
36 unsigned long *outlen)
38 unsigned long modulus_len, ps_len, i;
40 modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
42 /* test message size */
43 if ((msglen > modulus_len) || (modulus_len < 11))
44 return NULL;
46 /* separate encoded message */
47 if (msg[0] != 0x00 || msg[1] != 0x01)
48 return NULL;
50 for (i = 2; i < modulus_len - 1; i++)
51 if (msg[i] != 0xFF)
52 break;
54 /* separator check */
55 if (msg[i] != 0)
56 /* There was no octet with hexadecimal value 0x00
57 to separate ps from m. */
58 return NULL;
60 ps_len = i - 2;
62 *outlen = (msglen - (2 + ps_len + 1));
64 return msg + 2 + ps_len + 1;
68 * RSA Signature verification with public key
70 static int digsig_verify_rsa(struct key *key,
71 const char *sig, int siglen,
72 const char *h, int hlen)
74 int err = -EINVAL;
75 unsigned long len;
76 unsigned long mlen, mblen;
77 unsigned nret, l;
78 int head, i;
79 unsigned char *out1 = NULL;
80 const char *m;
81 MPI in = NULL, res = NULL, pkey[2];
82 uint8_t *p, *datap;
83 const uint8_t *endp;
84 const struct user_key_payload *ukp;
85 struct pubkey_hdr *pkh;
87 down_read(&key->sem);
88 ukp = user_key_payload(key);
90 if (ukp->datalen < sizeof(*pkh))
91 goto err1;
93 pkh = (struct pubkey_hdr *)ukp->data;
95 if (pkh->version != 1)
96 goto err1;
98 if (pkh->algo != PUBKEY_ALGO_RSA)
99 goto err1;
101 if (pkh->nmpi != 2)
102 goto err1;
104 datap = pkh->mpi;
105 endp = ukp->data + ukp->datalen;
107 err = -ENOMEM;
109 for (i = 0; i < pkh->nmpi; i++) {
110 unsigned int remaining = endp - datap;
111 pkey[i] = mpi_read_from_buffer(datap, &remaining);
112 if (!pkey[i])
113 goto err;
114 datap += remaining;
117 mblen = mpi_get_nbits(pkey[0]);
118 mlen = DIV_ROUND_UP(mblen, 8);
120 if (mlen == 0)
121 goto err;
123 out1 = kzalloc(mlen, GFP_KERNEL);
124 if (!out1)
125 goto err;
127 nret = siglen;
128 in = mpi_read_from_buffer(sig, &nret);
129 if (!in)
130 goto err;
132 res = mpi_alloc(mpi_get_nlimbs(in) * 2);
133 if (!res)
134 goto err;
136 err = mpi_powm(res, in, pkey[1], pkey[0]);
137 if (err)
138 goto err;
140 if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
141 err = -EINVAL;
142 goto err;
145 p = mpi_get_buffer(res, &l, NULL);
146 if (!p) {
147 err = -EINVAL;
148 goto err;
151 len = mlen;
152 head = len - l;
153 memset(out1, 0, head);
154 memcpy(out1 + head, p, l);
156 kfree(p);
158 m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
160 if (!m || len != hlen || memcmp(m, h, hlen))
161 err = -EINVAL;
163 err:
164 mpi_free(in);
165 mpi_free(res);
166 kfree(out1);
167 while (--i >= 0)
168 mpi_free(pkey[i]);
169 err1:
170 up_read(&key->sem);
172 return err;
176 * digsig_verify() - digital signature verification with public key
177 * @keyring: keyring to search key in
178 * @sig: digital signature
179 * @siglen: length of the signature
180 * @data: data
181 * @datalen: length of the data
183 * Returns 0 on success, -EINVAL otherwise
185 * Verifies data integrity against digital signature.
186 * Currently only RSA is supported.
187 * Normally hash of the content is used as a data for this function.
190 int digsig_verify(struct key *keyring, const char *sig, int siglen,
191 const char *data, int datalen)
193 int err = -ENOMEM;
194 struct signature_hdr *sh = (struct signature_hdr *)sig;
195 struct shash_desc *desc = NULL;
196 unsigned char hash[SHA1_DIGEST_SIZE];
197 struct key *key;
198 char name[20];
200 if (siglen < sizeof(*sh) + 2)
201 return -EINVAL;
203 if (sh->algo != PUBKEY_ALGO_RSA)
204 return -ENOTSUPP;
206 sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid));
208 if (keyring) {
209 /* search in specific keyring */
210 key_ref_t kref;
211 kref = keyring_search(make_key_ref(keyring, 1UL),
212 &key_type_user, name);
213 if (IS_ERR(kref))
214 key = ERR_CAST(kref);
215 else
216 key = key_ref_to_ptr(kref);
217 } else {
218 key = request_key(&key_type_user, name, NULL);
220 if (IS_ERR(key)) {
221 pr_err("key not found, id: %s\n", name);
222 return PTR_ERR(key);
225 desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
226 GFP_KERNEL);
227 if (!desc)
228 goto err;
230 desc->tfm = shash;
231 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
233 crypto_shash_init(desc);
234 crypto_shash_update(desc, data, datalen);
235 crypto_shash_update(desc, sig, sizeof(*sh));
236 crypto_shash_final(desc, hash);
238 kfree(desc);
240 /* pass signature mpis address */
241 err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
242 hash, sizeof(hash));
244 err:
245 key_put(key);
247 return err ? -EINVAL : 0;
249 EXPORT_SYMBOL_GPL(digsig_verify);
251 static int __init digsig_init(void)
253 shash = crypto_alloc_shash("sha1", 0, 0);
254 if (IS_ERR(shash)) {
255 pr_err("shash allocation failed\n");
256 return PTR_ERR(shash);
259 return 0;
263 static void __exit digsig_cleanup(void)
265 crypto_free_shash(shash);
268 module_init(digsig_init);
269 module_exit(digsig_cleanup);
271 MODULE_LICENSE("GPL");