1 /* $OpenBSD: auth2-chall.c,v 1.50 2018/07/11 18:55:11 markus Exp $ */
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
4 * Copyright (c) 2001 Per Allansson. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/types.h>
49 extern ServerOptions options;
51 static int auth2_challenge_start(struct ssh *);
52 static int send_userauth_info_request(struct ssh *);
53 static int input_userauth_info_response(int, u_int32_t, struct ssh *);
56 extern KbdintDevice bsdauth_device;
59 extern KbdintDevice sshpam_device;
63 KbdintDevice *devices[] = {
74 typedef struct KbdintAuthctxt KbdintAuthctxt;
86 remove_kbdint_device(const char *devname)
90 for (i = 0; devices[i] != NULL; i++)
91 if (strcmp(devices[i]->name, devname) == 0) {
92 for (j = i; devices[j] != NULL; j++)
93 devices[j] = devices[j+1];
99 static KbdintAuthctxt *
100 kbdint_alloc(const char *devs)
102 KbdintAuthctxt *kbdintctxt;
107 if (!options.use_pam)
108 remove_kbdint_device("pam");
111 kbdintctxt = xcalloc(1, sizeof(KbdintAuthctxt));
112 if (strcmp(devs, "") == 0) {
113 if ((b = sshbuf_new()) == NULL)
114 fatal("%s: sshbuf_new failed", __func__);
115 for (i = 0; devices[i]; i++) {
116 if ((r = sshbuf_putf(b, "%s%s",
117 sshbuf_len(b) ? "," : "", devices[i]->name)) != 0)
118 fatal("%s: buffer error: %s",
119 __func__, ssh_err(r));
121 if ((kbdintctxt->devices = sshbuf_dup_string(b)) == NULL)
122 fatal("%s: sshbuf_dup_string failed", __func__);
125 kbdintctxt->devices = xstrdup(devs);
127 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
128 kbdintctxt->ctxt = NULL;
129 kbdintctxt->device = NULL;
130 kbdintctxt->nreq = 0;
135 kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
137 if (kbdintctxt->ctxt) {
138 kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
139 kbdintctxt->ctxt = NULL;
141 kbdintctxt->device = NULL;
144 kbdint_free(KbdintAuthctxt *kbdintctxt)
146 if (kbdintctxt->device)
147 kbdint_reset_device(kbdintctxt);
148 free(kbdintctxt->devices);
149 explicit_bzero(kbdintctxt, sizeof(*kbdintctxt));
152 /* get next device */
154 kbdint_next_device(Authctxt *authctxt, KbdintAuthctxt *kbdintctxt)
160 if (kbdintctxt->device)
161 kbdint_reset_device(kbdintctxt);
163 len = kbdintctxt->devices ?
164 strcspn(kbdintctxt->devices, ",") : 0;
168 for (i = 0; devices[i]; i++) {
169 if ((kbdintctxt->devices_done & (1 << i)) != 0 ||
170 !auth2_method_allowed(authctxt,
171 "keyboard-interactive", devices[i]->name))
173 if (strncmp(kbdintctxt->devices, devices[i]->name,
175 kbdintctxt->device = devices[i];
176 kbdintctxt->devices_done |= 1 << i;
179 t = kbdintctxt->devices;
180 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
182 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
183 kbdintctxt->devices : "<empty>");
184 } while (kbdintctxt->devices && !kbdintctxt->device);
186 return kbdintctxt->device ? 1 : 0;
190 * try challenge-response, set authctxt->postponed if we have to
191 * wait for the response.
194 auth2_challenge(struct ssh *ssh, char *devs)
196 Authctxt *authctxt = ssh->authctxt;
197 debug("auth2_challenge: user=%s devs=%s",
198 authctxt->user ? authctxt->user : "<nouser>",
199 devs ? devs : "<no devs>");
201 if (authctxt->user == NULL || !devs)
203 if (authctxt->kbdintctxt == NULL)
204 authctxt->kbdintctxt = kbdint_alloc(devs);
205 return auth2_challenge_start(ssh);
208 /* unregister kbd-int callbacks and context */
210 auth2_challenge_stop(struct ssh *ssh)
212 Authctxt *authctxt = ssh->authctxt;
213 /* unregister callback */
214 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
215 if (authctxt->kbdintctxt != NULL) {
216 kbdint_free(authctxt->kbdintctxt);
217 authctxt->kbdintctxt = NULL;
221 /* side effect: sets authctxt->postponed if a reply was sent*/
223 auth2_challenge_start(struct ssh *ssh)
225 Authctxt *authctxt = ssh->authctxt;
226 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;
228 debug2("auth2_challenge_start: devices %s",
229 kbdintctxt->devices ? kbdintctxt->devices : "<empty>");
231 if (kbdint_next_device(authctxt, kbdintctxt) == 0) {
232 auth2_challenge_stop(ssh);
235 debug("auth2_challenge_start: trying authentication method '%s'",
236 kbdintctxt->device->name);
238 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
239 auth2_challenge_stop(ssh);
242 if (send_userauth_info_request(ssh) == 0) {
243 auth2_challenge_stop(ssh);
246 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE,
247 &input_userauth_info_response);
249 authctxt->postponed = 1;
254 send_userauth_info_request(struct ssh *ssh)
256 Authctxt *authctxt = ssh->authctxt;
257 KbdintAuthctxt *kbdintctxt;
258 char *name, *instr, **prompts;
259 u_int r, i, *echo_on;
261 kbdintctxt = authctxt->kbdintctxt;
262 if (kbdintctxt->device->query(kbdintctxt->ctxt,
263 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
266 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST)) != 0 ||
267 (r = sshpkt_put_cstring(ssh, name)) != 0 ||
268 (r = sshpkt_put_cstring(ssh, instr)) != 0 ||
269 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language not used */
270 (r = sshpkt_put_u32(ssh, kbdintctxt->nreq)) != 0)
271 fatal("%s: %s", __func__, ssh_err(r));
272 for (i = 0; i < kbdintctxt->nreq; i++) {
273 if ((r = sshpkt_put_cstring(ssh, prompts[i])) != 0 ||
274 (r = sshpkt_put_u8(ssh, echo_on[i])) != 0)
275 fatal("%s: %s", __func__, ssh_err(r));
277 if ((r = sshpkt_send(ssh)) != 0 ||
278 (r = ssh_packet_write_wait(ssh)) != 0)
279 fatal("%s: %s", __func__, ssh_err(r));
281 for (i = 0; i < kbdintctxt->nreq; i++)
291 input_userauth_info_response(int type, u_int32_t seq, struct ssh *ssh)
293 Authctxt *authctxt = ssh->authctxt;
294 KbdintAuthctxt *kbdintctxt;
295 int authenticated = 0, res;
298 const char *devicename = NULL;
299 char **response = NULL;
301 if (authctxt == NULL)
302 fatal("input_userauth_info_response: no authctxt");
303 kbdintctxt = authctxt->kbdintctxt;
304 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
305 fatal("input_userauth_info_response: no kbdintctxt");
306 if (kbdintctxt->device == NULL)
307 fatal("input_userauth_info_response: no device");
309 authctxt->postponed = 0; /* reset */
310 if ((r = sshpkt_get_u32(ssh, &nresp)) != 0)
311 fatal("%s: %s", __func__, ssh_err(r));
312 if (nresp != kbdintctxt->nreq)
313 fatal("input_userauth_info_response: wrong number of replies");
315 fatal("input_userauth_info_response: too many replies");
317 response = xcalloc(nresp, sizeof(char *));
318 for (i = 0; i < nresp; i++)
319 if ((r = sshpkt_get_cstring(ssh, &response[i],
321 fatal("%s: %s", __func__, ssh_err(r));
323 if ((r = sshpkt_get_end(ssh)) != 0)
324 fatal("%s: %s", __func__, ssh_err(r));
326 res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response);
328 for (i = 0; i < nresp; i++) {
329 explicit_bzero(response[i], strlen(response[i]));
337 authenticated = authctxt->valid ? 1 : 0;
340 /* Authentication needs further interaction */
341 if (send_userauth_info_request(ssh) == 1)
342 authctxt->postponed = 1;
348 devicename = kbdintctxt->device->name;
349 if (!authctxt->postponed) {
351 auth2_challenge_stop(ssh);
353 /* start next device */
354 /* may set authctxt->postponed */
355 auth2_challenge_start(ssh);
358 userauth_finish(ssh, authenticated, "keyboard-interactive",
364 privsep_challenge_enable(void)
366 #if defined(BSD_AUTH) || defined(USE_PAM)
370 extern KbdintDevice mm_bsdauth_device;
373 extern KbdintDevice mm_sshpam_device;
377 devices[n++] = &mm_bsdauth_device;
380 devices[n++] = &mm_sshpam_device;