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1 | /* | |
2 | * Copyright (c) 2001 Markus Friedl. All rights reserved. | |
3 | * Copyright (c) 2001 Per Allansson. 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 | #include "includes.h" | |
26 | RCSID("$OpenBSD: auth2-chall.c,v 1.21 2004/06/01 14:20:45 dtucker Exp $"); | |
27 | ||
28 | #include "ssh2.h" | |
29 | #include "auth.h" | |
30 | #include "buffer.h" | |
31 | #include "packet.h" | |
32 | #include "xmalloc.h" | |
33 | #include "dispatch.h" | |
34 | #include "log.h" | |
35 | ||
36 | static int auth2_challenge_start(Authctxt *); | |
37 | static int send_userauth_info_request(Authctxt *); | |
38 | static void input_userauth_info_response(int, u_int32_t, void *); | |
39 | ||
40 | #ifdef BSD_AUTH | |
41 | extern KbdintDevice bsdauth_device; | |
42 | #else | |
43 | #ifdef USE_PAM | |
44 | extern KbdintDevice sshpam_device; | |
45 | #endif | |
46 | #ifdef SKEY | |
47 | extern KbdintDevice skey_device; | |
48 | #endif | |
49 | #endif | |
50 | ||
51 | KbdintDevice *devices[] = { | |
52 | #ifdef BSD_AUTH | |
53 | &bsdauth_device, | |
54 | #else | |
55 | #ifdef USE_PAM | |
56 | &sshpam_device, | |
57 | #endif | |
58 | #ifdef SKEY | |
59 | &skey_device, | |
60 | #endif | |
61 | #endif | |
62 | NULL | |
63 | }; | |
64 | ||
65 | typedef struct KbdintAuthctxt KbdintAuthctxt; | |
66 | struct KbdintAuthctxt | |
67 | { | |
68 | char *devices; | |
69 | void *ctxt; | |
70 | KbdintDevice *device; | |
71 | u_int nreq; | |
72 | }; | |
73 | ||
74 | static KbdintAuthctxt * | |
75 | kbdint_alloc(const char *devs) | |
76 | { | |
77 | KbdintAuthctxt *kbdintctxt; | |
78 | Buffer b; | |
79 | int i; | |
80 | ||
81 | kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); | |
82 | if (strcmp(devs, "") == 0) { | |
83 | buffer_init(&b); | |
84 | for (i = 0; devices[i]; i++) { | |
85 | if (buffer_len(&b) > 0) | |
86 | buffer_append(&b, ",", 1); | |
87 | buffer_append(&b, devices[i]->name, | |
88 | strlen(devices[i]->name)); | |
89 | } | |
90 | buffer_append(&b, "\0", 1); | |
91 | kbdintctxt->devices = xstrdup(buffer_ptr(&b)); | |
92 | buffer_free(&b); | |
93 | } else { | |
94 | kbdintctxt->devices = xstrdup(devs); | |
95 | } | |
96 | debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); | |
97 | kbdintctxt->ctxt = NULL; | |
98 | kbdintctxt->device = NULL; | |
99 | kbdintctxt->nreq = 0; | |
100 | ||
101 | return kbdintctxt; | |
102 | } | |
103 | static void | |
104 | kbdint_reset_device(KbdintAuthctxt *kbdintctxt) | |
105 | { | |
106 | if (kbdintctxt->ctxt) { | |
107 | kbdintctxt->device->free_ctx(kbdintctxt->ctxt); | |
108 | kbdintctxt->ctxt = NULL; | |
109 | } | |
110 | kbdintctxt->device = NULL; | |
111 | } | |
112 | static void | |
113 | kbdint_free(KbdintAuthctxt *kbdintctxt) | |
114 | { | |
115 | if (kbdintctxt->device) | |
116 | kbdint_reset_device(kbdintctxt); | |
117 | if (kbdintctxt->devices) { | |
118 | xfree(kbdintctxt->devices); | |
119 | kbdintctxt->devices = NULL; | |
120 | } | |
121 | xfree(kbdintctxt); | |
122 | } | |
123 | /* get next device */ | |
124 | static int | |
125 | kbdint_next_device(KbdintAuthctxt *kbdintctxt) | |
126 | { | |
127 | size_t len; | |
128 | char *t; | |
129 | int i; | |
130 | ||
131 | if (kbdintctxt->device) | |
132 | kbdint_reset_device(kbdintctxt); | |
133 | do { | |
134 | len = kbdintctxt->devices ? | |
135 | strcspn(kbdintctxt->devices, ",") : 0; | |
136 | ||
137 | if (len == 0) | |
138 | break; | |
139 | for (i = 0; devices[i]; i++) | |
140 | if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) | |
141 | kbdintctxt->device = devices[i]; | |
142 | t = kbdintctxt->devices; | |
143 | kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; | |
144 | xfree(t); | |
145 | debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? | |
146 | kbdintctxt->devices : "<empty>"); | |
147 | } while (kbdintctxt->devices && !kbdintctxt->device); | |
148 | ||
149 | return kbdintctxt->device ? 1 : 0; | |
150 | } | |
151 | ||
152 | /* | |
153 | * try challenge-response, set authctxt->postponed if we have to | |
154 | * wait for the response. | |
155 | */ | |
156 | int | |
157 | auth2_challenge(Authctxt *authctxt, char *devs) | |
158 | { | |
159 | debug("auth2_challenge: user=%s devs=%s", | |
160 | authctxt->user ? authctxt->user : "<nouser>", | |
161 | devs ? devs : "<no devs>"); | |
162 | ||
163 | if (authctxt->user == NULL || !devs) | |
164 | return 0; | |
165 | if (authctxt->kbdintctxt == NULL) | |
166 | authctxt->kbdintctxt = kbdint_alloc(devs); | |
167 | return auth2_challenge_start(authctxt); | |
168 | } | |
169 | ||
170 | /* unregister kbd-int callbacks and context */ | |
171 | void | |
172 | auth2_challenge_stop(Authctxt *authctxt) | |
173 | { | |
174 | /* unregister callback */ | |
175 | dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); | |
176 | if (authctxt->kbdintctxt != NULL) { | |
177 | kbdint_free(authctxt->kbdintctxt); | |
178 | authctxt->kbdintctxt = NULL; | |
179 | } | |
180 | } | |
181 | ||
182 | /* side effect: sets authctxt->postponed if a reply was sent*/ | |
183 | static int | |
184 | auth2_challenge_start(Authctxt *authctxt) | |
185 | { | |
186 | KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; | |
187 | ||
188 | debug2("auth2_challenge_start: devices %s", | |
189 | kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); | |
190 | ||
191 | if (kbdint_next_device(kbdintctxt) == 0) { | |
192 | auth2_challenge_stop(authctxt); | |
193 | return 0; | |
194 | } | |
195 | debug("auth2_challenge_start: trying authentication method '%s'", | |
196 | kbdintctxt->device->name); | |
197 | ||
198 | if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { | |
199 | auth2_challenge_stop(authctxt); | |
200 | return 0; | |
201 | } | |
202 | if (send_userauth_info_request(authctxt) == 0) { | |
203 | auth2_challenge_stop(authctxt); | |
204 | return 0; | |
205 | } | |
206 | dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, | |
207 | &input_userauth_info_response); | |
208 | ||
209 | authctxt->postponed = 1; | |
210 | return 0; | |
211 | } | |
212 | ||
213 | static int | |
214 | send_userauth_info_request(Authctxt *authctxt) | |
215 | { | |
216 | KbdintAuthctxt *kbdintctxt; | |
217 | char *name, *instr, **prompts; | |
218 | int i; | |
219 | u_int *echo_on; | |
220 | ||
221 | kbdintctxt = authctxt->kbdintctxt; | |
222 | if (kbdintctxt->device->query(kbdintctxt->ctxt, | |
223 | &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) | |
224 | return 0; | |
225 | ||
226 | packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); | |
227 | packet_put_cstring(name); | |
228 | packet_put_cstring(instr); | |
229 | packet_put_cstring(""); /* language not used */ | |
230 | packet_put_int(kbdintctxt->nreq); | |
231 | for (i = 0; i < kbdintctxt->nreq; i++) { | |
232 | packet_put_cstring(prompts[i]); | |
233 | packet_put_char(echo_on[i]); | |
234 | } | |
235 | packet_send(); | |
236 | packet_write_wait(); | |
237 | ||
238 | for (i = 0; i < kbdintctxt->nreq; i++) | |
239 | xfree(prompts[i]); | |
240 | xfree(prompts); | |
241 | xfree(echo_on); | |
242 | xfree(name); | |
243 | xfree(instr); | |
244 | return 1; | |
245 | } | |
246 | ||
247 | static void | |
248 | input_userauth_info_response(int type, u_int32_t seq, void *ctxt) | |
249 | { | |
250 | Authctxt *authctxt = ctxt; | |
251 | KbdintAuthctxt *kbdintctxt; | |
252 | int i, authenticated = 0, res, len; | |
253 | u_int nresp; | |
254 | char **response = NULL, *method; | |
255 | ||
256 | if (authctxt == NULL) | |
257 | fatal("input_userauth_info_response: no authctxt"); | |
258 | kbdintctxt = authctxt->kbdintctxt; | |
259 | if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) | |
260 | fatal("input_userauth_info_response: no kbdintctxt"); | |
261 | if (kbdintctxt->device == NULL) | |
262 | fatal("input_userauth_info_response: no device"); | |
263 | ||
264 | authctxt->postponed = 0; /* reset */ | |
265 | nresp = packet_get_int(); | |
266 | if (nresp != kbdintctxt->nreq) | |
267 | fatal("input_userauth_info_response: wrong number of replies"); | |
268 | if (nresp > 100) | |
269 | fatal("input_userauth_info_response: too many replies"); | |
270 | if (nresp > 0) { | |
271 | response = xmalloc(nresp * sizeof(char *)); | |
272 | for (i = 0; i < nresp; i++) | |
273 | response[i] = packet_get_string(NULL); | |
274 | } | |
275 | packet_check_eom(); | |
276 | ||
277 | if (authctxt->valid) { | |
278 | res = kbdintctxt->device->respond(kbdintctxt->ctxt, | |
279 | nresp, response); | |
280 | } else { | |
281 | res = -1; | |
282 | } | |
283 | ||
284 | for (i = 0; i < nresp; i++) { | |
285 | memset(response[i], 'r', strlen(response[i])); | |
286 | xfree(response[i]); | |
287 | } | |
288 | if (response) | |
289 | xfree(response); | |
290 | ||
291 | switch (res) { | |
292 | case 0: | |
293 | /* Success! */ | |
294 | authenticated = 1; | |
295 | break; | |
296 | case 1: | |
297 | /* Authentication needs further interaction */ | |
298 | if (send_userauth_info_request(authctxt) == 1) | |
299 | authctxt->postponed = 1; | |
300 | break; | |
301 | default: | |
302 | /* Failure! */ | |
303 | break; | |
304 | } | |
305 | ||
306 | len = strlen("keyboard-interactive") + 2 + | |
307 | strlen(kbdintctxt->device->name); | |
308 | method = xmalloc(len); | |
309 | snprintf(method, len, "keyboard-interactive/%s", | |
310 | kbdintctxt->device->name); | |
311 | ||
312 | if (!authctxt->postponed) { | |
313 | if (authenticated) { | |
314 | auth2_challenge_stop(authctxt); | |
315 | } else { | |
316 | /* start next device */ | |
317 | /* may set authctxt->postponed */ | |
318 | auth2_challenge_start(authctxt); | |
319 | } | |
320 | } | |
321 | userauth_finish(authctxt, authenticated, method); | |
322 | xfree(method); | |
323 | } | |
324 | ||
325 | void | |
326 | privsep_challenge_enable(void) | |
327 | { | |
328 | #if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) | |
329 | int n = 0; | |
330 | #endif | |
331 | #ifdef BSD_AUTH | |
332 | extern KbdintDevice mm_bsdauth_device; | |
333 | #endif | |
334 | #ifdef USE_PAM | |
335 | extern KbdintDevice mm_sshpam_device; | |
336 | #endif | |
337 | #ifdef SKEY | |
338 | extern KbdintDevice mm_skey_device; | |
339 | #endif | |
340 | ||
341 | #ifdef BSD_AUTH | |
342 | devices[n++] = &mm_bsdauth_device; | |
343 | #else | |
344 | #ifdef USE_PAM | |
345 | devices[n++] = &mm_sshpam_device; | |
346 | #endif | |
347 | #ifdef SKEY | |
348 | devices[n++] = &mm_skey_device; | |
349 | #endif | |
350 | #endif | |
351 | } |