GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/ssh/lib/../ssh-rsa.c Lines: 0 168 0.0 %
Date: 2017-11-13 Branches: 0 132 0.0 %

Line Branch Exec Source
1
/* $OpenBSD: ssh-rsa.c,v 1.62 2017/07/01 13:50:45 djm Exp $ */
2
/*
3
 * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
4
 *
5
 * Permission to use, copy, modify, and distribute this software for any
6
 * purpose with or without fee is hereby granted, provided that the above
7
 * copyright notice and this permission notice appear in all copies.
8
 *
9
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16
 */
17
18
#include <sys/types.h>
19
20
#include <openssl/evp.h>
21
#include <openssl/err.h>
22
23
#include <string.h>
24
25
#include "sshbuf.h"
26
#include "compat.h"
27
#include "ssherr.h"
28
#define SSHKEY_INTERNAL
29
#include "sshkey.h"
30
#include "digest.h"
31
32
static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);
33
34
static const char *
35
rsa_hash_alg_ident(int hash_alg)
36
{
37
	switch (hash_alg) {
38
	case SSH_DIGEST_SHA1:
39
		return "ssh-rsa";
40
	case SSH_DIGEST_SHA256:
41
		return "rsa-sha2-256";
42
	case SSH_DIGEST_SHA512:
43
		return "rsa-sha2-512";
44
	}
45
	return NULL;
46
}
47
48
static int
49
rsa_hash_alg_from_ident(const char *ident)
50
{
51
	if (strcmp(ident, "ssh-rsa") == 0 ||
52
	    strcmp(ident, "ssh-rsa-cert-v01@openssh.com") == 0)
53
		return SSH_DIGEST_SHA1;
54
	if (strcmp(ident, "rsa-sha2-256") == 0)
55
		return SSH_DIGEST_SHA256;
56
	if (strcmp(ident, "rsa-sha2-512") == 0)
57
		return SSH_DIGEST_SHA512;
58
	return -1;
59
}
60
61
static int
62
rsa_hash_alg_nid(int type)
63
{
64
	switch (type) {
65
	case SSH_DIGEST_SHA1:
66
		return NID_sha1;
67
	case SSH_DIGEST_SHA256:
68
		return NID_sha256;
69
	case SSH_DIGEST_SHA512:
70
		return NID_sha512;
71
	default:
72
		return -1;
73
	}
74
}
75
76
/* calculate p-1 and q-1 */
77
int
78
ssh_rsa_generate_additional_parameters(struct sshkey *key)
79
{
80
	RSA *rsa;
81
	BIGNUM *aux = NULL;
82
	BN_CTX *ctx = NULL;
83
	int r;
84
85
	if (key == NULL || key->rsa == NULL ||
86
	    sshkey_type_plain(key->type) != KEY_RSA)
87
		return SSH_ERR_INVALID_ARGUMENT;
88
89
	if ((ctx = BN_CTX_new()) == NULL)
90
		return SSH_ERR_ALLOC_FAIL;
91
	if ((aux = BN_new()) == NULL) {
92
		r = SSH_ERR_ALLOC_FAIL;
93
		goto out;
94
	}
95
	rsa = key->rsa;
96
97
	if ((BN_sub(aux, rsa->q, BN_value_one()) == 0) ||
98
	    (BN_mod(rsa->dmq1, rsa->d, aux, ctx) == 0) ||
99
	    (BN_sub(aux, rsa->p, BN_value_one()) == 0) ||
100
	    (BN_mod(rsa->dmp1, rsa->d, aux, ctx) == 0)) {
101
		r = SSH_ERR_LIBCRYPTO_ERROR;
102
		goto out;
103
	}
104
	r = 0;
105
 out:
106
	BN_clear_free(aux);
107
	BN_CTX_free(ctx);
108
	return r;
109
}
110
111
/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
112
int
113
ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
114
    const u_char *data, size_t datalen, const char *alg_ident)
115
{
116
	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
117
	size_t slen;
118
	u_int dlen, len;
119
	int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
120
	struct sshbuf *b = NULL;
121
122
	if (lenp != NULL)
123
		*lenp = 0;
124
	if (sigp != NULL)
125
		*sigp = NULL;
126
127
	if (alg_ident == NULL || strlen(alg_ident) == 0)
128
		hash_alg = SSH_DIGEST_SHA1;
129
	else
130
		hash_alg = rsa_hash_alg_from_ident(alg_ident);
131
	if (key == NULL || key->rsa == NULL || hash_alg == -1 ||
132
	    sshkey_type_plain(key->type) != KEY_RSA)
133
		return SSH_ERR_INVALID_ARGUMENT;
134
	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
135
		return SSH_ERR_KEY_LENGTH;
136
	slen = RSA_size(key->rsa);
137
	if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
138
		return SSH_ERR_INVALID_ARGUMENT;
139
140
	/* hash the data */
141
	nid = rsa_hash_alg_nid(hash_alg);
142
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
143
		return SSH_ERR_INTERNAL_ERROR;
144
	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
145
	    digest, sizeof(digest))) != 0)
146
		goto out;
147
148
	if ((sig = malloc(slen)) == NULL) {
149
		ret = SSH_ERR_ALLOC_FAIL;
150
		goto out;
151
	}
152
153
	if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
154
		ret = SSH_ERR_LIBCRYPTO_ERROR;
155
		goto out;
156
	}
157
	if (len < slen) {
158
		size_t diff = slen - len;
159
		memmove(sig + diff, sig, len);
160
		explicit_bzero(sig, diff);
161
	} else if (len > slen) {
162
		ret = SSH_ERR_INTERNAL_ERROR;
163
		goto out;
164
	}
165
	/* encode signature */
166
	if ((b = sshbuf_new()) == NULL) {
167
		ret = SSH_ERR_ALLOC_FAIL;
168
		goto out;
169
	}
170
	if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 ||
171
	    (ret = sshbuf_put_string(b, sig, slen)) != 0)
172
		goto out;
173
	len = sshbuf_len(b);
174
	if (sigp != NULL) {
175
		if ((*sigp = malloc(len)) == NULL) {
176
			ret = SSH_ERR_ALLOC_FAIL;
177
			goto out;
178
		}
179
		memcpy(*sigp, sshbuf_ptr(b), len);
180
	}
181
	if (lenp != NULL)
182
		*lenp = len;
183
	ret = 0;
184
 out:
185
	explicit_bzero(digest, sizeof(digest));
186
	if (sig != NULL) {
187
		explicit_bzero(sig, slen);
188
		free(sig);
189
	}
190
	sshbuf_free(b);
191
	return ret;
192
}
193
194
int
195
ssh_rsa_verify(const struct sshkey *key,
196
    const u_char *sig, size_t siglen, const u_char *data, size_t datalen)
197
{
198
	char *ktype = NULL;
199
	int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
200
	size_t len, diff, modlen, dlen;
201
	struct sshbuf *b = NULL;
202
	u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;
203
204
	if (key == NULL || key->rsa == NULL ||
205
	    sshkey_type_plain(key->type) != KEY_RSA ||
206
	    sig == NULL || siglen == 0)
207
		return SSH_ERR_INVALID_ARGUMENT;
208
	if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
209
		return SSH_ERR_KEY_LENGTH;
210
211
	if ((b = sshbuf_from(sig, siglen)) == NULL)
212
		return SSH_ERR_ALLOC_FAIL;
213
	if (sshbuf_get_cstring(b, &ktype, NULL) != 0) {
214
		ret = SSH_ERR_INVALID_FORMAT;
215
		goto out;
216
	}
217
	if ((hash_alg = rsa_hash_alg_from_ident(ktype)) == -1) {
218
		ret = SSH_ERR_KEY_TYPE_MISMATCH;
219
		goto out;
220
	}
221
	if (sshbuf_get_string(b, &sigblob, &len) != 0) {
222
		ret = SSH_ERR_INVALID_FORMAT;
223
		goto out;
224
	}
225
	if (sshbuf_len(b) != 0) {
226
		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
227
		goto out;
228
	}
229
	/* RSA_verify expects a signature of RSA_size */
230
	modlen = RSA_size(key->rsa);
231
	if (len > modlen) {
232
		ret = SSH_ERR_KEY_BITS_MISMATCH;
233
		goto out;
234
	} else if (len < modlen) {
235
		diff = modlen - len;
236
		osigblob = sigblob;
237
		if ((sigblob = realloc(sigblob, modlen)) == NULL) {
238
			sigblob = osigblob; /* put it back for clear/free */
239
			ret = SSH_ERR_ALLOC_FAIL;
240
			goto out;
241
		}
242
		memmove(sigblob + diff, sigblob, len);
243
		explicit_bzero(sigblob, diff);
244
		len = modlen;
245
	}
246
	if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
247
		ret = SSH_ERR_INTERNAL_ERROR;
248
		goto out;
249
	}
250
	if ((ret = ssh_digest_memory(hash_alg, data, datalen,
251
	    digest, sizeof(digest))) != 0)
252
		goto out;
253
254
	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
255
	    key->rsa);
256
 out:
257
	if (sigblob != NULL) {
258
		explicit_bzero(sigblob, len);
259
		free(sigblob);
260
	}
261
	free(ktype);
262
	sshbuf_free(b);
263
	explicit_bzero(digest, sizeof(digest));
264
	return ret;
265
}
266
267
/*
268
 * See:
269
 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
270
 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
271
 */
272
273
/*
274
 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
275
 *	oiw(14) secsig(3) algorithms(2) 26 }
276
 */
277
static const u_char id_sha1[] = {
278
	0x30, 0x21, /* type Sequence, length 0x21 (33) */
279
	0x30, 0x09, /* type Sequence, length 0x09 */
280
	0x06, 0x05, /* type OID, length 0x05 */
281
	0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
282
	0x05, 0x00, /* NULL */
283
	0x04, 0x14  /* Octet string, length 0x14 (20), followed by sha1 hash */
284
};
285
286
/*
287
 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
288
 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
289
 *      organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
290
 *      id-sha256(1) }
291
 */
292
static const u_char id_sha256[] = {
293
	0x30, 0x31, /* type Sequence, length 0x31 (49) */
294
	0x30, 0x0d, /* type Sequence, length 0x0d (13) */
295
	0x06, 0x09, /* type OID, length 0x09 */
296
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */
297
	0x05, 0x00, /* NULL */
298
	0x04, 0x20  /* Octet string, length 0x20 (32), followed by sha256 hash */
299
};
300
301
/*
302
 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
303
 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
304
 *      organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
305
 *      id-sha256(3) }
306
 */
307
static const u_char id_sha512[] = {
308
	0x30, 0x51, /* type Sequence, length 0x51 (81) */
309
	0x30, 0x0d, /* type Sequence, length 0x0d (13) */
310
	0x06, 0x09, /* type OID, length 0x09 */
311
	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */
312
	0x05, 0x00, /* NULL */
313
	0x04, 0x40  /* Octet string, length 0x40 (64), followed by sha512 hash */
314
};
315
316
static int
317
rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)
318
{
319
	switch (hash_alg) {
320
	case SSH_DIGEST_SHA1:
321
		*oidp = id_sha1;
322
		*oidlenp = sizeof(id_sha1);
323
		break;
324
	case SSH_DIGEST_SHA256:
325
		*oidp = id_sha256;
326
		*oidlenp = sizeof(id_sha256);
327
		break;
328
	case SSH_DIGEST_SHA512:
329
		*oidp = id_sha512;
330
		*oidlenp = sizeof(id_sha512);
331
		break;
332
	default:
333
		return SSH_ERR_INVALID_ARGUMENT;
334
	}
335
	return 0;
336
}
337
338
static int
339
openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
340
    u_char *sigbuf, size_t siglen, RSA *rsa)
341
{
342
	size_t rsasize = 0, oidlen = 0, hlen = 0;
343
	int ret, len, oidmatch, hashmatch;
344
	const u_char *oid = NULL;
345
	u_char *decrypted = NULL;
346
347
	if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0)
348
		return ret;
349
	ret = SSH_ERR_INTERNAL_ERROR;
350
	hlen = ssh_digest_bytes(hash_alg);
351
	if (hashlen != hlen) {
352
		ret = SSH_ERR_INVALID_ARGUMENT;
353
		goto done;
354
	}
355
	rsasize = RSA_size(rsa);
356
	if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||
357
	    siglen == 0 || siglen > rsasize) {
358
		ret = SSH_ERR_INVALID_ARGUMENT;
359
		goto done;
360
	}
361
	if ((decrypted = malloc(rsasize)) == NULL) {
362
		ret = SSH_ERR_ALLOC_FAIL;
363
		goto done;
364
	}
365
	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
366
	    RSA_PKCS1_PADDING)) < 0) {
367
		ret = SSH_ERR_LIBCRYPTO_ERROR;
368
		goto done;
369
	}
370
	if (len < 0 || (size_t)len != hlen + oidlen) {
371
		ret = SSH_ERR_INVALID_FORMAT;
372
		goto done;
373
	}
374
	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
375
	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
376
	if (!oidmatch || !hashmatch) {
377
		ret = SSH_ERR_SIGNATURE_INVALID;
378
		goto done;
379
	}
380
	ret = 0;
381
done:
382
	if (decrypted) {
383
		explicit_bzero(decrypted, rsasize);
384
		free(decrypted);
385
	}
386
	return ret;
387
}