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v3.5.6
  1/*
  2 * Copyright (C) 2011 Nokia Corporation
  3 * Copyright (C) 2011 Intel Corporation
  4 *
  5 * Author:
  6 * Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
  7 *                 <dmitry.kasatkin@intel.com>
  8 *
  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.
 12 *
 13 * File: sign.c
 14 *	implements signature (RSA) verification
 15 *	pkcs decoding is based on LibTomCrypt code
 16 */
 17
 18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 19
 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>
 30
 31static struct crypto_shash *shash;
 32
 33static int pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
 34			unsigned long  msglen,
 35			unsigned long  modulus_bitlen,
 36			unsigned char *out,
 37			unsigned long *outlen)
 38{
 39	unsigned long modulus_len, ps_len, i;
 40
 41	modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
 42
 43	/* test message size */
 44	if ((msglen > modulus_len) || (modulus_len < 11))
 45		return -EINVAL;
 46
 47	/* separate encoded message */
 48	if ((msg[0] != 0x00) || (msg[1] != (unsigned char)1))
 49		return -EINVAL;
 50
 51	for (i = 2; i < modulus_len - 1; i++)
 52		if (msg[i] != 0xFF)
 53			break;
 54
 55	/* separator check */
 56	if (msg[i] != 0)
 57		/* There was no octet with hexadecimal value 0x00
 58		to separate ps from m. */
 59		return -EINVAL;
 60
 61	ps_len = i - 2;
 62
 63	if (*outlen < (msglen - (2 + ps_len + 1))) {
 64		*outlen = msglen - (2 + ps_len + 1);
 65		return -EOVERFLOW;
 66	}
 67
 68	*outlen = (msglen - (2 + ps_len + 1));
 69	memcpy(out, &msg[2 + ps_len + 1], *outlen);
 70
 71	return 0;
 72}
 73
 74/*
 75 * RSA Signature verification with public key
 76 */
 77static int digsig_verify_rsa(struct key *key,
 78		    const char *sig, int siglen,
 79		       const char *h, int hlen)
 80{
 81	int err = -EINVAL;
 82	unsigned long len;
 83	unsigned long mlen, mblen;
 84	unsigned nret, l;
 85	int head, i;
 86	unsigned char *out1 = NULL, *out2 = NULL;
 
 87	MPI in = NULL, res = NULL, pkey[2];
 88	uint8_t *p, *datap, *endp;
 89	struct user_key_payload *ukp;
 
 90	struct pubkey_hdr *pkh;
 91
 92	down_read(&key->sem);
 93	ukp = key->payload.data;
 
 
 
 
 
 
 94
 95	if (ukp->datalen < sizeof(*pkh))
 96		goto err1;
 97
 98	pkh = (struct pubkey_hdr *)ukp->data;
 99
100	if (pkh->version != 1)
101		goto err1;
102
103	if (pkh->algo != PUBKEY_ALGO_RSA)
104		goto err1;
105
106	if (pkh->nmpi != 2)
107		goto err1;
108
109	datap = pkh->mpi;
110	endp = ukp->data + ukp->datalen;
111
112	err = -ENOMEM;
113
114	for (i = 0; i < pkh->nmpi; i++) {
115		unsigned int remaining = endp - datap;
116		pkey[i] = mpi_read_from_buffer(datap, &remaining);
117		if (!pkey[i])
 
118			goto err;
 
119		datap += remaining;
120	}
121
122	mblen = mpi_get_nbits(pkey[0]);
123	mlen = (mblen + 7)/8;
124
125	if (mlen == 0)
 
126		goto err;
 
 
 
127
128	out1 = kzalloc(mlen, GFP_KERNEL);
129	if (!out1)
130		goto err;
131
132	out2 = kzalloc(mlen, GFP_KERNEL);
133	if (!out2)
134		goto err;
135
136	nret = siglen;
137	in = mpi_read_from_buffer(sig, &nret);
138	if (!in)
 
139		goto err;
 
140
141	res = mpi_alloc(mpi_get_nlimbs(in) * 2);
142	if (!res)
143		goto err;
144
145	err = mpi_powm(res, in, pkey[1], pkey[0]);
146	if (err)
147		goto err;
148
149	if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
150		err = -EINVAL;
151		goto err;
152	}
153
154	p = mpi_get_buffer(res, &l, NULL);
155	if (!p) {
156		err = -EINVAL;
157		goto err;
158	}
159
160	len = mlen;
161	head = len - l;
162	memset(out1, 0, head);
163	memcpy(out1 + head, p, l);
164
165	err = pkcs_1_v1_5_decode_emsa(out1, len, mblen, out2, &len);
166	if (err)
167		goto err;
168
169	if (len != hlen || memcmp(out2, h, hlen))
 
 
170		err = -EINVAL;
171
172err:
173	mpi_free(in);
174	mpi_free(res);
175	kfree(out1);
176	kfree(out2);
177	while (--i >= 0)
178		mpi_free(pkey[i]);
179err1:
180	up_read(&key->sem);
181
182	return err;
183}
184
185/**
186 * digsig_verify() - digital signature verification with public key
187 * @keyring:	keyring to search key in
188 * @sig:	digital signature
189 * @sigen:	length of the signature
190 * @data:	data
191 * @datalen:	length of the data
192 * @return:	0 on success, -EINVAL otherwise
 
193 *
194 * Verifies data integrity against digital signature.
195 * Currently only RSA is supported.
196 * Normally hash of the content is used as a data for this function.
197 *
198 */
199int digsig_verify(struct key *keyring, const char *sig, int siglen,
200						const char *data, int datalen)
201{
202	int err = -ENOMEM;
203	struct signature_hdr *sh = (struct signature_hdr *)sig;
204	struct shash_desc *desc = NULL;
205	unsigned char hash[SHA1_DIGEST_SIZE];
206	struct key *key;
207	char name[20];
208
209	if (siglen < sizeof(*sh) + 2)
210		return -EINVAL;
211
212	if (sh->algo != PUBKEY_ALGO_RSA)
213		return -ENOTSUPP;
214
215	sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid));
216
217	if (keyring) {
218		/* search in specific keyring */
219		key_ref_t kref;
220		kref = keyring_search(make_key_ref(keyring, 1UL),
221						&key_type_user, name);
222		if (IS_ERR(kref))
223			key = ERR_PTR(PTR_ERR(kref));
224		else
225			key = key_ref_to_ptr(kref);
226	} else {
227		key = request_key(&key_type_user, name, NULL);
228	}
229	if (IS_ERR(key)) {
230		pr_err("key not found, id: %s\n", name);
231		return PTR_ERR(key);
232	}
233
234	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
235		       GFP_KERNEL);
236	if (!desc)
237		goto err;
238
239	desc->tfm = shash;
240	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
241
242	crypto_shash_init(desc);
243	crypto_shash_update(desc, data, datalen);
244	crypto_shash_update(desc, sig, sizeof(*sh));
245	crypto_shash_final(desc, hash);
246
247	kfree(desc);
248
249	/* pass signature mpis address */
250	err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
251			     hash, sizeof(hash));
252
253err:
254	key_put(key);
255
256	return err ? -EINVAL : 0;
257}
258EXPORT_SYMBOL_GPL(digsig_verify);
259
260static int __init digsig_init(void)
261{
262	shash = crypto_alloc_shash("sha1", 0, 0);
263	if (IS_ERR(shash)) {
264		pr_err("shash allocation failed\n");
265		return  PTR_ERR(shash);
266	}
267
268	return 0;
269
270}
271
272static void __exit digsig_cleanup(void)
273{
274	crypto_free_shash(shash);
275}
276
277module_init(digsig_init);
278module_exit(digsig_cleanup);
279
280MODULE_LICENSE("GPL");
v4.17
  1/*
  2 * Copyright (C) 2011 Nokia Corporation
  3 * Copyright (C) 2011 Intel Corporation
  4 *
  5 * Author:
  6 * Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
  7 *                 <dmitry.kasatkin@intel.com>
  8 *
  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.
 12 *
 13 * File: sign.c
 14 *	implements signature (RSA) verification
 15 *	pkcs decoding is based on LibTomCrypt code
 16 */
 17
 18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 19
 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>
 30
 31static struct crypto_shash *shash;
 32
 33static 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)
 
 37{
 38	unsigned long modulus_len, ps_len, i;
 39
 40	modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0);
 41
 42	/* test message size */
 43	if ((msglen > modulus_len) || (modulus_len < 11))
 44		return NULL;
 45
 46	/* separate encoded message */
 47	if (msg[0] != 0x00 || msg[1] != 0x01)
 48		return NULL;
 49
 50	for (i = 2; i < modulus_len - 1; i++)
 51		if (msg[i] != 0xFF)
 52			break;
 53
 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;
 59
 60	ps_len = i - 2;
 61
 
 
 
 
 
 62	*outlen = (msglen - (2 + ps_len + 1));
 
 63
 64	return msg + 2 + ps_len + 1;
 65}
 66
 67/*
 68 * RSA Signature verification with public key
 69 */
 70static int digsig_verify_rsa(struct key *key,
 71		    const char *sig, int siglen,
 72		       const char *h, int hlen)
 73{
 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;
 86
 87	down_read(&key->sem);
 88	ukp = user_key_payload_locked(key);
 89
 90	if (!ukp) {
 91		/* key was revoked before we acquired its semaphore */
 92		err = -EKEYREVOKED;
 93		goto err1;
 94	}
 95
 96	if (ukp->datalen < sizeof(*pkh))
 97		goto err1;
 98
 99	pkh = (struct pubkey_hdr *)ukp->data;
100
101	if (pkh->version != 1)
102		goto err1;
103
104	if (pkh->algo != PUBKEY_ALGO_RSA)
105		goto err1;
106
107	if (pkh->nmpi != 2)
108		goto err1;
109
110	datap = pkh->mpi;
111	endp = ukp->data + ukp->datalen;
112
 
 
113	for (i = 0; i < pkh->nmpi; i++) {
114		unsigned int remaining = endp - datap;
115		pkey[i] = mpi_read_from_buffer(datap, &remaining);
116		if (IS_ERR(pkey[i])) {
117			err = PTR_ERR(pkey[i]);
118			goto err;
119		}
120		datap += remaining;
121	}
122
123	mblen = mpi_get_nbits(pkey[0]);
124	mlen = DIV_ROUND_UP(mblen, 8);
125
126	if (mlen == 0) {
127		err = -EINVAL;
128		goto err;
129	}
130
131	err = -ENOMEM;
132
133	out1 = kzalloc(mlen, GFP_KERNEL);
134	if (!out1)
135		goto err;
136
 
 
 
 
137	nret = siglen;
138	in = mpi_read_from_buffer(sig, &nret);
139	if (IS_ERR(in)) {
140		err = PTR_ERR(in);
141		goto err;
142	}
143
144	res = mpi_alloc(mpi_get_nlimbs(in) * 2);
145	if (!res)
146		goto err;
147
148	err = mpi_powm(res, in, pkey[1], pkey[0]);
149	if (err)
150		goto err;
151
152	if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) {
153		err = -EINVAL;
154		goto err;
155	}
156
157	p = mpi_get_buffer(res, &l, NULL);
158	if (!p) {
159		err = -EINVAL;
160		goto err;
161	}
162
163	len = mlen;
164	head = len - l;
165	memset(out1, 0, head);
166	memcpy(out1 + head, p, l);
167
168	kfree(p);
 
 
169
170	m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len);
171
172	if (!m || len != hlen || memcmp(m, h, hlen))
173		err = -EINVAL;
174
175err:
176	mpi_free(in);
177	mpi_free(res);
178	kfree(out1);
 
179	while (--i >= 0)
180		mpi_free(pkey[i]);
181err1:
182	up_read(&key->sem);
183
184	return err;
185}
186
187/**
188 * digsig_verify() - digital signature verification with public key
189 * @keyring:	keyring to search key in
190 * @sig:	digital signature
191 * @siglen:	length of the signature
192 * @data:	data
193 * @datalen:	length of the data
194 *
195 * Returns 0 on success, -EINVAL otherwise
196 *
197 * Verifies data integrity against digital signature.
198 * Currently only RSA is supported.
199 * Normally hash of the content is used as a data for this function.
200 *
201 */
202int digsig_verify(struct key *keyring, const char *sig, int siglen,
203						const char *data, int datalen)
204{
205	int err = -ENOMEM;
206	struct signature_hdr *sh = (struct signature_hdr *)sig;
207	struct shash_desc *desc = NULL;
208	unsigned char hash[SHA1_DIGEST_SIZE];
209	struct key *key;
210	char name[20];
211
212	if (siglen < sizeof(*sh) + 2)
213		return -EINVAL;
214
215	if (sh->algo != PUBKEY_ALGO_RSA)
216		return -ENOTSUPP;
217
218	sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid));
219
220	if (keyring) {
221		/* search in specific keyring */
222		key_ref_t kref;
223		kref = keyring_search(make_key_ref(keyring, 1UL),
224						&key_type_user, name);
225		if (IS_ERR(kref))
226			key = ERR_CAST(kref);
227		else
228			key = key_ref_to_ptr(kref);
229	} else {
230		key = request_key(&key_type_user, name, NULL);
231	}
232	if (IS_ERR(key)) {
233		pr_err("key not found, id: %s\n", name);
234		return PTR_ERR(key);
235	}
236
237	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
238		       GFP_KERNEL);
239	if (!desc)
240		goto err;
241
242	desc->tfm = shash;
243	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
244
245	crypto_shash_init(desc);
246	crypto_shash_update(desc, data, datalen);
247	crypto_shash_update(desc, sig, sizeof(*sh));
248	crypto_shash_final(desc, hash);
249
250	kfree(desc);
251
252	/* pass signature mpis address */
253	err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
254			     hash, sizeof(hash));
255
256err:
257	key_put(key);
258
259	return err ? -EINVAL : 0;
260}
261EXPORT_SYMBOL_GPL(digsig_verify);
262
263static int __init digsig_init(void)
264{
265	shash = crypto_alloc_shash("sha1", 0, 0);
266	if (IS_ERR(shash)) {
267		pr_err("shash allocation failed\n");
268		return  PTR_ERR(shash);
269	}
270
271	return 0;
272
273}
274
275static void __exit digsig_cleanup(void)
276{
277	crypto_free_shash(shash);
278}
279
280module_init(digsig_init);
281module_exit(digsig_cleanup);
282
283MODULE_LICENSE("GPL");