Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.46
1.46 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.45 2022/10/28 00:41:52 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.23 deraadt 26: #include <sys/types.h>
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.22 stevesk 30:
31: #include <string.h>
1.1 markus 32:
1.32 djm 33: #include "sshbuf.h"
1.1 markus 34: #include "compat.h"
1.32 djm 35: #include "ssherr.h"
1.30 djm 36: #include "digest.h"
1.32 djm 37: #define SSHKEY_INTERNAL
38: #include "sshkey.h"
1.1 markus 39:
40: #define INTBLOB_LEN 20
41: #define SIGBLOB_LEN (2*INTBLOB_LEN)
42:
1.40 djm 43: static u_int
44: ssh_dss_size(const struct sshkey *key)
45: {
46: const BIGNUM *dsa_p;
47:
48: if (key->dsa == NULL)
49: return 0;
50: DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL);
51: return BN_num_bits(dsa_p);
52: }
53:
54: static int
55: ssh_dss_alloc(struct sshkey *k)
56: {
57: if ((k->dsa = DSA_new()) == NULL)
58: return SSH_ERR_ALLOC_FAIL;
59: return 0;
60: }
61:
62: static void
63: ssh_dss_cleanup(struct sshkey *k)
64: {
65: DSA_free(k->dsa);
66: k->dsa = NULL;
67: }
68:
1.41 djm 69: static int
70: ssh_dss_equal(const struct sshkey *a, const struct sshkey *b)
71: {
72: const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a;
73: const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b;
74:
75: if (a->dsa == NULL || b->dsa == NULL)
76: return 0;
77: DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a);
78: DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b);
79: DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL);
80: DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL);
81: if (dsa_p_a == NULL || dsa_p_b == NULL ||
82: dsa_q_a == NULL || dsa_q_b == NULL ||
83: dsa_g_a == NULL || dsa_g_b == NULL ||
84: dsa_pub_key_a == NULL || dsa_pub_key_b == NULL)
85: return 0;
86: if (BN_cmp(dsa_p_a, dsa_p_b) != 0)
87: return 0;
88: if (BN_cmp(dsa_q_a, dsa_q_b) != 0)
89: return 0;
90: if (BN_cmp(dsa_g_a, dsa_g_b) != 0)
91: return 0;
92: if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0)
93: return 0;
94: return 1;
95: }
96:
1.42 djm 97: static int
98: ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b,
1.45 djm 99: enum sshkey_serialize_rep opts)
1.42 djm 100: {
101: int r;
102: const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
103:
104: if (key->dsa == NULL)
105: return SSH_ERR_INVALID_ARGUMENT;
106: DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g);
107: DSA_get0_key(key->dsa, &dsa_pub_key, NULL);
108: if (dsa_p == NULL || dsa_q == NULL ||
109: dsa_g == NULL || dsa_pub_key == NULL)
110: return SSH_ERR_INTERNAL_ERROR;
1.45 djm 111: if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
1.42 djm 112: (r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
113: (r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
114: (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
115: return r;
116:
117: return 0;
118: }
119:
1.43 djm 120: static int
121: ssh_dss_generate(struct sshkey *k, int bits)
122: {
123: DSA *private;
124:
125: if (bits != 1024)
126: return SSH_ERR_KEY_LENGTH;
127: if ((private = DSA_new()) == NULL)
128: return SSH_ERR_ALLOC_FAIL;
129: if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
130: NULL, NULL) || !DSA_generate_key(private)) {
131: DSA_free(private);
132: return SSH_ERR_LIBCRYPTO_ERROR;
133: }
134: k->dsa = private;
135: return 0;
136: }
137:
1.44 djm 138: static int
139: ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
140: {
141: const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
142: BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
143: BIGNUM *dsa_pub_key_dup = NULL;
144: int r = SSH_ERR_INTERNAL_ERROR;
145:
146: DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
147: DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
148: if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
149: (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
150: (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
151: (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
152: r = SSH_ERR_ALLOC_FAIL;
153: goto out;
154: }
155: if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
156: r = SSH_ERR_LIBCRYPTO_ERROR;
157: goto out;
158: }
159: dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
160: if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
161: r = SSH_ERR_LIBCRYPTO_ERROR;
162: goto out;
163: }
164: dsa_pub_key_dup = NULL; /* transferred */
165: /* success */
166: r = 0;
167: out:
168: BN_clear_free(dsa_p_dup);
169: BN_clear_free(dsa_q_dup);
170: BN_clear_free(dsa_g_dup);
171: BN_clear_free(dsa_pub_key_dup);
172: return r;
173: }
174:
1.45 djm 175: static int
176: ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b,
177: struct sshkey *key)
178: {
179: int ret = SSH_ERR_INTERNAL_ERROR;
180: BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL;
181:
182: if (sshbuf_get_bignum2(b, &dsa_p) != 0 ||
183: sshbuf_get_bignum2(b, &dsa_q) != 0 ||
184: sshbuf_get_bignum2(b, &dsa_g) != 0 ||
185: sshbuf_get_bignum2(b, &dsa_pub_key) != 0) {
186: ret = SSH_ERR_INVALID_FORMAT;
187: goto out;
188: }
189: if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) {
190: ret = SSH_ERR_LIBCRYPTO_ERROR;
191: goto out;
192: }
193: dsa_p = dsa_q = dsa_g = NULL; /* transferred */
194: if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) {
195: ret = SSH_ERR_LIBCRYPTO_ERROR;
196: goto out;
197: }
198: dsa_pub_key = NULL; /* transferred */
199: #ifdef DEBUG_PK
200: DSA_print_fp(stderr, key->dsa, 8);
201: #endif
202: /* success */
203: ret = 0;
204: out:
205: BN_clear_free(dsa_p);
206: BN_clear_free(dsa_q);
207: BN_clear_free(dsa_g);
208: BN_clear_free(dsa_pub_key);
209: return ret;
210: }
211:
1.46 ! djm 212: static int
! 213: ssh_dss_sign(struct sshkey *key,
! 214: u_char **sigp, size_t *lenp,
! 215: const u_char *data, size_t datalen,
! 216: const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
1.1 markus 217: {
1.32 djm 218: DSA_SIG *sig = NULL;
1.38 djm 219: const BIGNUM *sig_r, *sig_s;
1.30 djm 220: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 221: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
222: struct sshbuf *b = NULL;
223: int ret = SSH_ERR_INVALID_ARGUMENT;
224:
225: if (lenp != NULL)
226: *lenp = 0;
227: if (sigp != NULL)
228: *sigp = NULL;
229:
230: if (key == NULL || key->dsa == NULL ||
231: sshkey_type_plain(key->type) != KEY_DSA)
232: return SSH_ERR_INVALID_ARGUMENT;
233: if (dlen == 0)
234: return SSH_ERR_INTERNAL_ERROR;
235:
236: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
237: digest, sizeof(digest))) != 0)
238: goto out;
239:
240: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
241: ret = SSH_ERR_LIBCRYPTO_ERROR;
242: goto out;
1.1 markus 243: }
244:
1.38 djm 245: DSA_SIG_get0(sig, &sig_r, &sig_s);
246: rlen = BN_num_bytes(sig_r);
247: slen = BN_num_bytes(sig_s);
1.1 markus 248: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 249: ret = SSH_ERR_INTERNAL_ERROR;
250: goto out;
1.1 markus 251: }
1.31 djm 252: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 djm 253: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
254: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 255:
1.36 djm 256: if ((b = sshbuf_new()) == NULL) {
257: ret = SSH_ERR_ALLOC_FAIL;
258: goto out;
259: }
260: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
261: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
262: goto out;
263:
264: len = sshbuf_len(b);
265: if (sigp != NULL) {
266: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 267: ret = SSH_ERR_ALLOC_FAIL;
268: goto out;
269: }
1.36 djm 270: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 271: }
1.36 djm 272: if (lenp != NULL)
273: *lenp = len;
274: ret = 0;
1.32 djm 275: out:
276: explicit_bzero(digest, sizeof(digest));
1.37 jsing 277: DSA_SIG_free(sig);
1.34 mmcc 278: sshbuf_free(b);
1.32 djm 279: return ret;
1.1 markus 280: }
1.32 djm 281:
1.46 ! djm 282: static int
1.32 djm 283: ssh_dss_verify(const struct sshkey *key,
1.46 ! djm 284: const u_char *sig, size_t siglen,
! 285: const u_char *data, size_t dlen, const char *alg, u_int compat,
! 286: struct sshkey_sig_details **detailsp)
1.1 markus 287: {
1.46 ! djm 288: DSA_SIG *dsig = NULL;
1.38 djm 289: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 290: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
1.46 ! djm 291: size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
1.32 djm 292: int ret = SSH_ERR_INTERNAL_ERROR;
293: struct sshbuf *b = NULL;
294: char *ktype = NULL;
295:
296: if (key == NULL || key->dsa == NULL ||
1.35 djm 297: sshkey_type_plain(key->type) != KEY_DSA ||
1.46 ! djm 298: sig == NULL || siglen == 0)
1.32 djm 299: return SSH_ERR_INVALID_ARGUMENT;
1.46 ! djm 300: if (hlen == 0)
1.32 djm 301: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 302:
303: /* fetch signature */
1.46 ! djm 304: if ((b = sshbuf_from(sig, siglen)) == NULL)
1.36 djm 305: return SSH_ERR_ALLOC_FAIL;
306: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
307: sshbuf_get_string(b, &sigblob, &len) != 0) {
308: ret = SSH_ERR_INVALID_FORMAT;
309: goto out;
310: }
311: if (strcmp("ssh-dss", ktype) != 0) {
312: ret = SSH_ERR_KEY_TYPE_MISMATCH;
313: goto out;
314: }
315: if (sshbuf_len(b) != 0) {
316: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
317: goto out;
1.1 markus 318: }
319:
320: if (len != SIGBLOB_LEN) {
1.32 djm 321: ret = SSH_ERR_INVALID_FORMAT;
322: goto out;
1.1 markus 323: }
324:
325: /* parse signature */
1.46 ! djm 326: if ((dsig = DSA_SIG_new()) == NULL ||
1.38 djm 327: (sig_r = BN_new()) == NULL ||
328: (sig_s = BN_new()) == NULL) {
1.32 djm 329: ret = SSH_ERR_ALLOC_FAIL;
330: goto out;
331: }
1.38 djm 332: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
333: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 334: ret = SSH_ERR_LIBCRYPTO_ERROR;
335: goto out;
336: }
1.46 ! djm 337: if (!DSA_SIG_set0(dsig, sig_r, sig_s)) {
1.38 djm 338: ret = SSH_ERR_LIBCRYPTO_ERROR;
339: goto out;
340: }
341: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 342:
1.1 markus 343: /* sha1 the data */
1.46 ! djm 344: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen,
1.32 djm 345: digest, sizeof(digest))) != 0)
346: goto out;
347:
1.46 ! djm 348: switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) {
1.32 djm 349: case 1:
350: ret = 0;
351: break;
352: case 0:
353: ret = SSH_ERR_SIGNATURE_INVALID;
354: goto out;
355: default:
356: ret = SSH_ERR_LIBCRYPTO_ERROR;
357: goto out;
1.30 djm 358: }
1.1 markus 359:
1.32 djm 360: out:
1.31 djm 361: explicit_bzero(digest, sizeof(digest));
1.46 ! djm 362: DSA_SIG_free(dsig);
1.38 djm 363: BN_clear_free(sig_r);
364: BN_clear_free(sig_s);
1.34 mmcc 365: sshbuf_free(b);
1.33 mmcc 366: free(ktype);
1.39 jsg 367: if (sigblob != NULL)
368: freezero(sigblob, len);
1.1 markus 369: return ret;
370: }
1.40 djm 371:
372: static const struct sshkey_impl_funcs sshkey_dss_funcs = {
373: /* .size = */ ssh_dss_size,
374: /* .alloc = */ ssh_dss_alloc,
375: /* .cleanup = */ ssh_dss_cleanup,
1.41 djm 376: /* .equal = */ ssh_dss_equal,
1.42 djm 377: /* .ssh_serialize_public = */ ssh_dss_serialize_public,
1.45 djm 378: /* .ssh_deserialize_public = */ ssh_dss_deserialize_public,
1.43 djm 379: /* .generate = */ ssh_dss_generate,
1.44 djm 380: /* .copy_public = */ ssh_dss_copy_public,
1.46 ! djm 381: /* .sign = */ ssh_dss_sign,
! 382: /* .verify = */ ssh_dss_verify,
1.40 djm 383: };
384:
385: const struct sshkey_impl sshkey_dss_impl = {
386: /* .name = */ "ssh-dss",
387: /* .shortname = */ "DSA",
388: /* .sigalg = */ NULL,
389: /* .type = */ KEY_DSA,
390: /* .nid = */ 0,
391: /* .cert = */ 0,
392: /* .sigonly = */ 0,
393: /* .keybits = */ 0,
394: /* .funcs = */ &sshkey_dss_funcs,
395: };
396:
397: const struct sshkey_impl sshkey_dsa_cert_impl = {
398: /* .name = */ "ssh-dss-cert-v01@openssh.com",
399: /* .shortname = */ "DSA-CERT",
400: /* .sigalg = */ NULL,
401: /* .type = */ KEY_DSA_CERT,
402: /* .nid = */ 0,
403: /* .cert = */ 1,
404: /* .sigonly = */ 0,
405: /* .keybits = */ 0,
406: /* .funcs = */ &sshkey_dss_funcs,
407: };