Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.41
1.41 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.40 2022/10/28 00:35:40 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:
1.1 markus 97: int
1.32 djm 98: ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
99: const u_char *data, size_t datalen, u_int compat)
1.1 markus 100: {
1.32 djm 101: DSA_SIG *sig = NULL;
1.38 djm 102: const BIGNUM *sig_r, *sig_s;
1.30 djm 103: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 104: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
105: struct sshbuf *b = NULL;
106: int ret = SSH_ERR_INVALID_ARGUMENT;
107:
108: if (lenp != NULL)
109: *lenp = 0;
110: if (sigp != NULL)
111: *sigp = NULL;
112:
113: if (key == NULL || key->dsa == NULL ||
114: sshkey_type_plain(key->type) != KEY_DSA)
115: return SSH_ERR_INVALID_ARGUMENT;
116: if (dlen == 0)
117: return SSH_ERR_INTERNAL_ERROR;
118:
119: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
120: digest, sizeof(digest))) != 0)
121: goto out;
122:
123: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
124: ret = SSH_ERR_LIBCRYPTO_ERROR;
125: goto out;
1.1 markus 126: }
127:
1.38 djm 128: DSA_SIG_get0(sig, &sig_r, &sig_s);
129: rlen = BN_num_bytes(sig_r);
130: slen = BN_num_bytes(sig_s);
1.1 markus 131: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 132: ret = SSH_ERR_INTERNAL_ERROR;
133: goto out;
1.1 markus 134: }
1.31 djm 135: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 djm 136: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
137: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 138:
1.36 djm 139: if ((b = sshbuf_new()) == NULL) {
140: ret = SSH_ERR_ALLOC_FAIL;
141: goto out;
142: }
143: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
144: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
145: goto out;
146:
147: len = sshbuf_len(b);
148: if (sigp != NULL) {
149: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 150: ret = SSH_ERR_ALLOC_FAIL;
151: goto out;
152: }
1.36 djm 153: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 154: }
1.36 djm 155: if (lenp != NULL)
156: *lenp = len;
157: ret = 0;
1.32 djm 158: out:
159: explicit_bzero(digest, sizeof(digest));
1.37 jsing 160: DSA_SIG_free(sig);
1.34 mmcc 161: sshbuf_free(b);
1.32 djm 162: return ret;
1.1 markus 163: }
1.32 djm 164:
1.1 markus 165: int
1.32 djm 166: ssh_dss_verify(const struct sshkey *key,
167: const u_char *signature, size_t signaturelen,
168: const u_char *data, size_t datalen, u_int compat)
1.1 markus 169: {
1.32 djm 170: DSA_SIG *sig = NULL;
1.38 djm 171: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 172: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
173: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
174: int ret = SSH_ERR_INTERNAL_ERROR;
175: struct sshbuf *b = NULL;
176: char *ktype = NULL;
177:
178: if (key == NULL || key->dsa == NULL ||
1.35 djm 179: sshkey_type_plain(key->type) != KEY_DSA ||
180: signature == NULL || signaturelen == 0)
1.32 djm 181: return SSH_ERR_INVALID_ARGUMENT;
182: if (dlen == 0)
183: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 184:
185: /* fetch signature */
1.36 djm 186: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
187: return SSH_ERR_ALLOC_FAIL;
188: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
189: sshbuf_get_string(b, &sigblob, &len) != 0) {
190: ret = SSH_ERR_INVALID_FORMAT;
191: goto out;
192: }
193: if (strcmp("ssh-dss", ktype) != 0) {
194: ret = SSH_ERR_KEY_TYPE_MISMATCH;
195: goto out;
196: }
197: if (sshbuf_len(b) != 0) {
198: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
199: goto out;
1.1 markus 200: }
201:
202: if (len != SIGBLOB_LEN) {
1.32 djm 203: ret = SSH_ERR_INVALID_FORMAT;
204: goto out;
1.1 markus 205: }
206:
207: /* parse signature */
1.32 djm 208: if ((sig = DSA_SIG_new()) == NULL ||
1.38 djm 209: (sig_r = BN_new()) == NULL ||
210: (sig_s = BN_new()) == NULL) {
1.32 djm 211: ret = SSH_ERR_ALLOC_FAIL;
212: goto out;
213: }
1.38 djm 214: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
215: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 216: ret = SSH_ERR_LIBCRYPTO_ERROR;
217: goto out;
218: }
1.38 djm 219: if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
220: ret = SSH_ERR_LIBCRYPTO_ERROR;
221: goto out;
222: }
223: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 224:
1.1 markus 225: /* sha1 the data */
1.32 djm 226: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
227: digest, sizeof(digest))) != 0)
228: goto out;
229:
230: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
231: case 1:
232: ret = 0;
233: break;
234: case 0:
235: ret = SSH_ERR_SIGNATURE_INVALID;
236: goto out;
237: default:
238: ret = SSH_ERR_LIBCRYPTO_ERROR;
239: goto out;
1.30 djm 240: }
1.1 markus 241:
1.32 djm 242: out:
1.31 djm 243: explicit_bzero(digest, sizeof(digest));
1.37 jsing 244: DSA_SIG_free(sig);
1.38 djm 245: BN_clear_free(sig_r);
246: BN_clear_free(sig_s);
1.34 mmcc 247: sshbuf_free(b);
1.33 mmcc 248: free(ktype);
1.39 jsg 249: if (sigblob != NULL)
250: freezero(sigblob, len);
1.1 markus 251: return ret;
252: }
1.40 djm 253:
254: static const struct sshkey_impl_funcs sshkey_dss_funcs = {
255: /* .size = */ ssh_dss_size,
256: /* .alloc = */ ssh_dss_alloc,
257: /* .cleanup = */ ssh_dss_cleanup,
1.41 ! djm 258: /* .equal = */ ssh_dss_equal,
1.40 djm 259: };
260:
261: const struct sshkey_impl sshkey_dss_impl = {
262: /* .name = */ "ssh-dss",
263: /* .shortname = */ "DSA",
264: /* .sigalg = */ NULL,
265: /* .type = */ KEY_DSA,
266: /* .nid = */ 0,
267: /* .cert = */ 0,
268: /* .sigonly = */ 0,
269: /* .keybits = */ 0,
270: /* .funcs = */ &sshkey_dss_funcs,
271: };
272:
273: const struct sshkey_impl sshkey_dsa_cert_impl = {
274: /* .name = */ "ssh-dss-cert-v01@openssh.com",
275: /* .shortname = */ "DSA-CERT",
276: /* .sigalg = */ NULL,
277: /* .type = */ KEY_DSA_CERT,
278: /* .nid = */ 0,
279: /* .cert = */ 1,
280: /* .sigonly = */ 0,
281: /* .keybits = */ 0,
282: /* .funcs = */ &sshkey_dss_funcs,
283: };
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