1 /* $OpenBSD: ssh-xmss.c,v 1.14 2022/10/28 00:44:44 djm Exp $*/
2 /*
3 * Copyright (c) 2017 Stefan-Lukas Gazdag.
4 * Copyright (c) 2017 Markus Friedl.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18 #include "includes.h"
19 #ifdef WITH_XMSS
20
21 #define SSHKEY_INTERNAL
22 #include <sys/types.h>
23 #include <limits.h>
24
25 #include <stdlib.h>
26 #include <string.h>
27 #include <stdarg.h>
28 #ifdef HAVE_STDINT_H
29 # include <stdint.h>
30 #endif
31 #include <unistd.h>
32
33 #include "log.h"
34 #include "sshbuf.h"
35 #include "sshkey.h"
36 #include "sshkey-xmss.h"
37 #include "ssherr.h"
38 #include "ssh.h"
39
40 #include "xmss_fast.h"
41
42 static void
ssh_xmss_cleanup(struct sshkey * k)43 ssh_xmss_cleanup(struct sshkey *k)
44 {
45 freezero(k->xmss_pk, sshkey_xmss_pklen(k));
46 freezero(k->xmss_sk, sshkey_xmss_sklen(k));
47 sshkey_xmss_free_state(k);
48 free(k->xmss_name);
49 free(k->xmss_filename);
50 k->xmss_pk = NULL;
51 k->xmss_sk = NULL;
52 k->xmss_name = NULL;
53 k->xmss_filename = NULL;
54 }
55
56 static int
ssh_xmss_equal(const struct sshkey * a,const struct sshkey * b)57 ssh_xmss_equal(const struct sshkey *a, const struct sshkey *b)
58 {
59 if (a->xmss_pk == NULL || b->xmss_pk == NULL)
60 return 0;
61 if (sshkey_xmss_pklen(a) != sshkey_xmss_pklen(b))
62 return 0;
63 if (memcmp(a->xmss_pk, b->xmss_pk, sshkey_xmss_pklen(a)) != 0)
64 return 0;
65 return 1;
66 }
67
68 static int
ssh_xmss_serialize_public(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)69 ssh_xmss_serialize_public(const struct sshkey *key, struct sshbuf *b,
70 enum sshkey_serialize_rep opts)
71 {
72 int r;
73
74 if (key->xmss_name == NULL || key->xmss_pk == NULL ||
75 sshkey_xmss_pklen(key) == 0)
76 return SSH_ERR_INVALID_ARGUMENT;
77 if ((r = sshbuf_put_cstring(b, key->xmss_name)) != 0 ||
78 (r = sshbuf_put_string(b, key->xmss_pk,
79 sshkey_xmss_pklen(key))) != 0 ||
80 (r = sshkey_xmss_serialize_pk_info(key, b, opts)) != 0)
81 return r;
82
83 return 0;
84 }
85
86 static int
ssh_xmss_serialize_private(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)87 ssh_xmss_serialize_private(const struct sshkey *key, struct sshbuf *b,
88 enum sshkey_serialize_rep opts)
89 {
90 int r;
91
92 if (key->xmss_name == NULL)
93 return SSH_ERR_INVALID_ARGUMENT;
94 /* Note: can't reuse ssh_xmss_serialize_public because of sk order */
95 if ((r = sshbuf_put_cstring(b, key->xmss_name)) != 0 ||
96 (r = sshbuf_put_string(b, key->xmss_pk,
97 sshkey_xmss_pklen(key))) != 0 ||
98 (r = sshbuf_put_string(b, key->xmss_sk,
99 sshkey_xmss_sklen(key))) != 0 ||
100 (r = sshkey_xmss_serialize_state_opt(key, b, opts)) != 0)
101 return r;
102
103 return 0;
104 }
105
106 static int
ssh_xmss_copy_public(const struct sshkey * from,struct sshkey * to)107 ssh_xmss_copy_public(const struct sshkey *from, struct sshkey *to)
108 {
109 int r = SSH_ERR_INTERNAL_ERROR;
110 u_int32_t left;
111 size_t pklen;
112
113 if ((r = sshkey_xmss_init(to, from->xmss_name)) != 0)
114 return r;
115 if (from->xmss_pk == NULL)
116 return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
117
118 if ((pklen = sshkey_xmss_pklen(from)) == 0 ||
119 sshkey_xmss_pklen(to) != pklen)
120 return SSH_ERR_INTERNAL_ERROR;
121 if ((to->xmss_pk = malloc(pklen)) == NULL)
122 return SSH_ERR_ALLOC_FAIL;
123 memcpy(to->xmss_pk, from->xmss_pk, pklen);
124 /* simulate number of signatures left on pubkey */
125 left = sshkey_xmss_signatures_left(from);
126 if (left)
127 sshkey_xmss_enable_maxsign(to, left);
128 return 0;
129 }
130
131 static int
ssh_xmss_deserialize_public(const char * ktype,struct sshbuf * b,struct sshkey * key)132 ssh_xmss_deserialize_public(const char *ktype, struct sshbuf *b,
133 struct sshkey *key)
134 {
135 size_t len = 0;
136 char *xmss_name = NULL;
137 u_char *pk = NULL;
138 int ret = SSH_ERR_INTERNAL_ERROR;
139
140 if ((ret = sshbuf_get_cstring(b, &xmss_name, NULL)) != 0)
141 goto out;
142 if ((ret = sshkey_xmss_init(key, xmss_name)) != 0)
143 goto out;
144 if ((ret = sshbuf_get_string(b, &pk, &len)) != 0)
145 goto out;
146 if (len == 0 || len != sshkey_xmss_pklen(key)) {
147 ret = SSH_ERR_INVALID_FORMAT;
148 goto out;
149 }
150 key->xmss_pk = pk;
151 pk = NULL;
152 if (!sshkey_is_cert(key) &&
153 (ret = sshkey_xmss_deserialize_pk_info(key, b)) != 0)
154 goto out;
155 /* success */
156 ret = 0;
157 out:
158 free(xmss_name);
159 freezero(pk, len);
160 return ret;
161 }
162
163 static int
ssh_xmss_deserialize_private(const char * ktype,struct sshbuf * b,struct sshkey * key)164 ssh_xmss_deserialize_private(const char *ktype, struct sshbuf *b,
165 struct sshkey *key)
166 {
167 int r;
168 char *xmss_name = NULL;
169 size_t pklen = 0, sklen = 0;
170 u_char *xmss_pk = NULL, *xmss_sk = NULL;
171
172 /* Note: can't reuse ssh_xmss_deserialize_public because of sk order */
173 if ((r = sshbuf_get_cstring(b, &xmss_name, NULL)) != 0 ||
174 (r = sshbuf_get_string(b, &xmss_pk, &pklen)) != 0 ||
175 (r = sshbuf_get_string(b, &xmss_sk, &sklen)) != 0)
176 goto out;
177 if (!sshkey_is_cert(key) &&
178 (r = sshkey_xmss_init(key, xmss_name)) != 0)
179 goto out;
180 if (pklen != sshkey_xmss_pklen(key) ||
181 sklen != sshkey_xmss_sklen(key)) {
182 r = SSH_ERR_INVALID_FORMAT;
183 goto out;
184 }
185 key->xmss_pk = xmss_pk;
186 key->xmss_sk = xmss_sk;
187 xmss_pk = xmss_sk = NULL;
188 /* optional internal state */
189 if ((r = sshkey_xmss_deserialize_state_opt(key, b)) != 0)
190 goto out;
191 /* success */
192 r = 0;
193 out:
194 free(xmss_name);
195 freezero(xmss_pk, pklen);
196 freezero(xmss_sk, sklen);
197 return r;
198 }
199
200 static int
ssh_xmss_sign(struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,const char * alg,const char * sk_provider,const char * sk_pin,u_int compat)201 ssh_xmss_sign(struct sshkey *key,
202 u_char **sigp, size_t *lenp,
203 const u_char *data, size_t datalen,
204 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
205 {
206 u_char *sig = NULL;
207 size_t slen = 0, len = 0, required_siglen;
208 unsigned long long smlen;
209 int r, ret;
210 struct sshbuf *b = NULL;
211
212 if (lenp != NULL)
213 *lenp = 0;
214 if (sigp != NULL)
215 *sigp = NULL;
216
217 if (key == NULL ||
218 sshkey_type_plain(key->type) != KEY_XMSS ||
219 key->xmss_sk == NULL ||
220 sshkey_xmss_params(key) == NULL)
221 return SSH_ERR_INVALID_ARGUMENT;
222 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
223 return r;
224 if (datalen >= INT_MAX - required_siglen)
225 return SSH_ERR_INVALID_ARGUMENT;
226 smlen = slen = datalen + required_siglen;
227 if ((sig = malloc(slen)) == NULL)
228 return SSH_ERR_ALLOC_FAIL;
229 if ((r = sshkey_xmss_get_state(key, 1)) != 0)
230 goto out;
231 if ((ret = xmss_sign(key->xmss_sk, sshkey_xmss_bds_state(key), sig, &smlen,
232 data, datalen, sshkey_xmss_params(key))) != 0 || smlen <= datalen) {
233 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
234 goto out;
235 }
236 /* encode signature */
237 if ((b = sshbuf_new()) == NULL) {
238 r = SSH_ERR_ALLOC_FAIL;
239 goto out;
240 }
241 if ((r = sshbuf_put_cstring(b, "ssh-xmss@openssh.com")) != 0 ||
242 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
243 goto out;
244 len = sshbuf_len(b);
245 if (sigp != NULL) {
246 if ((*sigp = malloc(len)) == NULL) {
247 r = SSH_ERR_ALLOC_FAIL;
248 goto out;
249 }
250 memcpy(*sigp, sshbuf_ptr(b), len);
251 }
252 if (lenp != NULL)
253 *lenp = len;
254 /* success */
255 r = 0;
256 out:
257 if ((ret = sshkey_xmss_update_state(key, 1)) != 0) {
258 /* discard signature since we cannot update the state */
259 if (r == 0 && sigp != NULL && *sigp != NULL) {
260 explicit_bzero(*sigp, len);
261 free(*sigp);
262 }
263 if (sigp != NULL)
264 *sigp = NULL;
265 if (lenp != NULL)
266 *lenp = 0;
267 r = ret;
268 }
269 sshbuf_free(b);
270 if (sig != NULL)
271 freezero(sig, slen);
272
273 return r;
274 }
275
276 static int
ssh_xmss_verify(const struct sshkey * key,const u_char * sig,size_t siglen,const u_char * data,size_t dlen,const char * alg,u_int compat,struct sshkey_sig_details ** detailsp)277 ssh_xmss_verify(const struct sshkey *key,
278 const u_char *sig, size_t siglen,
279 const u_char *data, size_t dlen, const char *alg, u_int compat,
280 struct sshkey_sig_details **detailsp)
281 {
282 struct sshbuf *b = NULL;
283 char *ktype = NULL;
284 const u_char *sigblob;
285 u_char *sm = NULL, *m = NULL;
286 size_t len, required_siglen;
287 unsigned long long smlen = 0, mlen = 0;
288 int r, ret;
289
290 if (key == NULL ||
291 sshkey_type_plain(key->type) != KEY_XMSS ||
292 key->xmss_pk == NULL ||
293 sshkey_xmss_params(key) == NULL ||
294 sig == NULL || siglen == 0)
295 return SSH_ERR_INVALID_ARGUMENT;
296 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
297 return r;
298 if (dlen >= INT_MAX - required_siglen)
299 return SSH_ERR_INVALID_ARGUMENT;
300
301 if ((b = sshbuf_from(sig, siglen)) == NULL)
302 return SSH_ERR_ALLOC_FAIL;
303 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
304 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
305 goto out;
306 if (strcmp("ssh-xmss@openssh.com", ktype) != 0) {
307 r = SSH_ERR_KEY_TYPE_MISMATCH;
308 goto out;
309 }
310 if (sshbuf_len(b) != 0) {
311 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
312 goto out;
313 }
314 if (len != required_siglen) {
315 r = SSH_ERR_INVALID_FORMAT;
316 goto out;
317 }
318 if (dlen >= SIZE_MAX - len) {
319 r = SSH_ERR_INVALID_ARGUMENT;
320 goto out;
321 }
322 smlen = len + dlen;
323 mlen = smlen;
324 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
325 r = SSH_ERR_ALLOC_FAIL;
326 goto out;
327 }
328 memcpy(sm, sigblob, len);
329 memcpy(sm+len, data, dlen);
330 if ((ret = xmss_sign_open(m, &mlen, sm, smlen,
331 key->xmss_pk, sshkey_xmss_params(key))) != 0) {
332 debug2_f("xmss_sign_open failed: %d", ret);
333 }
334 if (ret != 0 || mlen != dlen) {
335 r = SSH_ERR_SIGNATURE_INVALID;
336 goto out;
337 }
338 /* XXX compare 'm' and 'data' ? */
339 /* success */
340 r = 0;
341 out:
342 if (sm != NULL)
343 freezero(sm, smlen);
344 if (m != NULL)
345 freezero(m, smlen);
346 sshbuf_free(b);
347 free(ktype);
348 return r;
349 }
350
351 static const struct sshkey_impl_funcs sshkey_xmss_funcs = {
352 /* .size = */ NULL,
353 /* .alloc = */ NULL,
354 /* .cleanup = */ ssh_xmss_cleanup,
355 /* .equal = */ ssh_xmss_equal,
356 /* .ssh_serialize_public = */ ssh_xmss_serialize_public,
357 /* .ssh_deserialize_public = */ ssh_xmss_deserialize_public,
358 /* .ssh_serialize_private = */ ssh_xmss_serialize_private,
359 /* .ssh_deserialize_private = */ ssh_xmss_deserialize_private,
360 /* .generate = */ sshkey_xmss_generate_private_key,
361 /* .copy_public = */ ssh_xmss_copy_public,
362 /* .sign = */ ssh_xmss_sign,
363 /* .verify = */ ssh_xmss_verify,
364 };
365
366 const struct sshkey_impl sshkey_xmss_impl = {
367 /* .name = */ "ssh-xmss@openssh.com",
368 /* .shortname = */ "XMSS",
369 /* .sigalg = */ NULL,
370 /* .type = */ KEY_XMSS,
371 /* .nid = */ 0,
372 /* .cert = */ 0,
373 /* .sigonly = */ 0,
374 /* .keybits = */ 256,
375 /* .funcs = */ &sshkey_xmss_funcs,
376 };
377
378 const struct sshkey_impl sshkey_xmss_cert_impl = {
379 /* .name = */ "ssh-xmss-cert-v01@openssh.com",
380 /* .shortname = */ "XMSS-CERT",
381 /* .sigalg = */ NULL,
382 /* .type = */ KEY_XMSS_CERT,
383 /* .nid = */ 0,
384 /* .cert = */ 1,
385 /* .sigonly = */ 0,
386 /* .keybits = */ 256,
387 /* .funcs = */ &sshkey_xmss_funcs,
388 };
389 #endif /* WITH_XMSS */
390