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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 1.20 2002/06/30 21:59:45 deraadt 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 "auth.h" | |
35 | #include "log.h" | |
36 | ||
37 | static int auth2_challenge_start(Authctxt *); | |
38 | static int send_userauth_info_request(Authctxt *); | |
39 | static void input_userauth_info_response(int, u_int32_t, void *); | |
40 | ||
41 | #ifdef BSD_AUTH | |
42 | extern KbdintDevice bsdauth_device; | |
43 | #else | |
44 | #ifdef SKEY | |
45 | extern KbdintDevice skey_device; | |
46 | #endif | |
47 | #endif | |
48 | ||
49 | KbdintDevice *devices[] = { | |
50 | #ifdef BSD_AUTH | |
51 | &bsdauth_device, | |
52 | #else | |
53 | #ifdef SKEY | |
54 | &skey_device, | |
55 | #endif | |
56 | #endif | |
57 | NULL | |
58 | }; | |
59 | ||
60 | typedef struct KbdintAuthctxt KbdintAuthctxt; | |
61 | struct KbdintAuthctxt | |
62 | { | |
63 | char *devices; | |
64 | void *ctxt; | |
65 | KbdintDevice *device; | |
66 | u_int nreq; | |
67 | }; | |
68 | ||
69 | static KbdintAuthctxt * | |
70 | kbdint_alloc(const char *devs) | |
71 | { | |
72 | KbdintAuthctxt *kbdintctxt; | |
73 | Buffer b; | |
74 | int i; | |
75 | ||
76 | kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); | |
77 | if (strcmp(devs, "") == 0) { | |
78 | buffer_init(&b); | |
79 | for (i = 0; devices[i]; i++) { | |
80 | if (buffer_len(&b) > 0) | |
81 | buffer_append(&b, ",", 1); | |
82 | buffer_append(&b, devices[i]->name, | |
83 | strlen(devices[i]->name)); | |
84 | } | |
85 | buffer_append(&b, "\0", 1); | |
86 | kbdintctxt->devices = xstrdup(buffer_ptr(&b)); | |
87 | buffer_free(&b); | |
88 | } else { | |
89 | kbdintctxt->devices = xstrdup(devs); | |
90 | } | |
91 | debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); | |
92 | kbdintctxt->ctxt = NULL; | |
93 | kbdintctxt->device = NULL; | |
94 | kbdintctxt->nreq = 0; | |
95 | ||
96 | return kbdintctxt; | |
97 | } | |
98 | static void | |
99 | kbdint_reset_device(KbdintAuthctxt *kbdintctxt) | |
100 | { | |
101 | if (kbdintctxt->ctxt) { | |
102 | kbdintctxt->device->free_ctx(kbdintctxt->ctxt); | |
103 | kbdintctxt->ctxt = NULL; | |
104 | } | |
105 | kbdintctxt->device = NULL; | |
106 | } | |
107 | static void | |
108 | kbdint_free(KbdintAuthctxt *kbdintctxt) | |
109 | { | |
110 | if (kbdintctxt->device) | |
111 | kbdint_reset_device(kbdintctxt); | |
112 | if (kbdintctxt->devices) { | |
113 | xfree(kbdintctxt->devices); | |
114 | kbdintctxt->devices = NULL; | |
115 | } | |
116 | xfree(kbdintctxt); | |
117 | } | |
118 | /* get next device */ | |
119 | static int | |
120 | kbdint_next_device(KbdintAuthctxt *kbdintctxt) | |
121 | { | |
122 | size_t len; | |
123 | char *t; | |
124 | int i; | |
125 | ||
126 | if (kbdintctxt->device) | |
127 | kbdint_reset_device(kbdintctxt); | |
128 | do { | |
129 | len = kbdintctxt->devices ? | |
130 | strcspn(kbdintctxt->devices, ",") : 0; | |
131 | ||
132 | if (len == 0) | |
133 | break; | |
134 | for (i = 0; devices[i]; i++) | |
135 | if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) | |
136 | kbdintctxt->device = devices[i]; | |
137 | t = kbdintctxt->devices; | |
138 | kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; | |
139 | xfree(t); | |
140 | debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? | |
141 | kbdintctxt->devices : "<empty>"); | |
142 | } while (kbdintctxt->devices && !kbdintctxt->device); | |
143 | ||
144 | return kbdintctxt->device ? 1 : 0; | |
145 | } | |
146 | ||
147 | /* | |
148 | * try challenge-response, set authctxt->postponed if we have to | |
149 | * wait for the response. | |
150 | */ | |
151 | int | |
152 | auth2_challenge(Authctxt *authctxt, char *devs) | |
153 | { | |
154 | debug("auth2_challenge: user=%s devs=%s", | |
155 | authctxt->user ? authctxt->user : "<nouser>", | |
156 | devs ? devs : "<no devs>"); | |
157 | ||
158 | if (authctxt->user == NULL || !devs) | |
159 | return 0; | |
160 | if (authctxt->kbdintctxt == NULL) | |
161 | authctxt->kbdintctxt = kbdint_alloc(devs); | |
162 | return auth2_challenge_start(authctxt); | |
163 | } | |
164 | ||
165 | /* unregister kbd-int callbacks and context */ | |
166 | void | |
167 | auth2_challenge_stop(Authctxt *authctxt) | |
168 | { | |
169 | /* unregister callback */ | |
170 | dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); | |
171 | if (authctxt->kbdintctxt != NULL) { | |
172 | kbdint_free(authctxt->kbdintctxt); | |
173 | authctxt->kbdintctxt = NULL; | |
174 | } | |
175 | } | |
176 | ||
177 | /* side effect: sets authctxt->postponed if a reply was sent*/ | |
178 | static int | |
179 | auth2_challenge_start(Authctxt *authctxt) | |
180 | { | |
181 | KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; | |
182 | ||
183 | debug2("auth2_challenge_start: devices %s", | |
184 | kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); | |
185 | ||
186 | if (kbdint_next_device(kbdintctxt) == 0) { | |
187 | auth2_challenge_stop(authctxt); | |
188 | return 0; | |
189 | } | |
190 | debug("auth2_challenge_start: trying authentication method '%s'", | |
191 | kbdintctxt->device->name); | |
192 | ||
193 | if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { | |
194 | auth2_challenge_stop(authctxt); | |
195 | return 0; | |
196 | } | |
197 | if (send_userauth_info_request(authctxt) == 0) { | |
198 | auth2_challenge_stop(authctxt); | |
199 | return 0; | |
200 | } | |
201 | dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, | |
202 | &input_userauth_info_response); | |
203 | ||
204 | authctxt->postponed = 1; | |
205 | return 0; | |
206 | } | |
207 | ||
208 | static int | |
209 | send_userauth_info_request(Authctxt *authctxt) | |
210 | { | |
211 | KbdintAuthctxt *kbdintctxt; | |
212 | char *name, *instr, **prompts; | |
213 | int i; | |
214 | u_int *echo_on; | |
215 | ||
216 | kbdintctxt = authctxt->kbdintctxt; | |
217 | if (kbdintctxt->device->query(kbdintctxt->ctxt, | |
218 | &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) | |
219 | return 0; | |
220 | ||
221 | packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); | |
222 | packet_put_cstring(name); | |
223 | packet_put_cstring(instr); | |
224 | packet_put_cstring(""); /* language not used */ | |
225 | packet_put_int(kbdintctxt->nreq); | |
226 | for (i = 0; i < kbdintctxt->nreq; i++) { | |
227 | packet_put_cstring(prompts[i]); | |
228 | packet_put_char(echo_on[i]); | |
229 | } | |
230 | packet_send(); | |
231 | packet_write_wait(); | |
232 | ||
233 | for (i = 0; i < kbdintctxt->nreq; i++) | |
234 | xfree(prompts[i]); | |
235 | xfree(prompts); | |
236 | xfree(echo_on); | |
237 | xfree(name); | |
238 | xfree(instr); | |
239 | return 1; | |
240 | } | |
241 | ||
242 | static void | |
243 | input_userauth_info_response(int type, u_int32_t seq, void *ctxt) | |
244 | { | |
245 | Authctxt *authctxt = ctxt; | |
246 | KbdintAuthctxt *kbdintctxt; | |
247 | int i, authenticated = 0, res, len; | |
248 | u_int nresp; | |
249 | char **response = NULL, *method; | |
250 | ||
251 | if (authctxt == NULL) | |
252 | fatal("input_userauth_info_response: no authctxt"); | |
253 | kbdintctxt = authctxt->kbdintctxt; | |
254 | if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) | |
255 | fatal("input_userauth_info_response: no kbdintctxt"); | |
256 | if (kbdintctxt->device == NULL) | |
257 | fatal("input_userauth_info_response: no device"); | |
258 | ||
259 | authctxt->postponed = 0; /* reset */ | |
260 | nresp = packet_get_int(); | |
261 | if (nresp != kbdintctxt->nreq) | |
262 | fatal("input_userauth_info_response: wrong number of replies"); | |
263 | if (nresp > 100) | |
264 | fatal("input_userauth_info_response: too many replies"); | |
265 | if (nresp > 0) { | |
266 | response = xmalloc(nresp * sizeof(char *)); | |
267 | for (i = 0; i < nresp; i++) | |
268 | response[i] = packet_get_string(NULL); | |
269 | } | |
270 | packet_check_eom(); | |
271 | ||
272 | if (authctxt->valid) { | |
273 | res = kbdintctxt->device->respond(kbdintctxt->ctxt, | |
274 | nresp, response); | |
275 | } else { | |
276 | res = -1; | |
277 | } | |
278 | ||
279 | for (i = 0; i < nresp; i++) { | |
280 | memset(response[i], 'r', strlen(response[i])); | |
281 | xfree(response[i]); | |
282 | } | |
283 | if (response) | |
284 | xfree(response); | |
285 | ||
286 | switch (res) { | |
287 | case 0: | |
288 | /* Success! */ | |
289 | authenticated = 1; | |
290 | break; | |
291 | case 1: | |
292 | /* Authentication needs further interaction */ | |
293 | if (send_userauth_info_request(authctxt) == 1) | |
294 | authctxt->postponed = 1; | |
295 | break; | |
296 | default: | |
297 | /* Failure! */ | |
298 | break; | |
299 | } | |
300 | ||
301 | len = strlen("keyboard-interactive") + 2 + | |
302 | strlen(kbdintctxt->device->name); | |
303 | method = xmalloc(len); | |
304 | snprintf(method, len, "keyboard-interactive/%s", | |
305 | kbdintctxt->device->name); | |
306 | ||
307 | if (!authctxt->postponed) { | |
308 | if (authenticated) { | |
309 | auth2_challenge_stop(authctxt); | |
310 | } else { | |
311 | /* start next device */ | |
312 | /* may set authctxt->postponed */ | |
313 | auth2_challenge_start(authctxt); | |
314 | } | |
315 | } | |
316 | userauth_finish(authctxt, authenticated, method); | |
317 | xfree(method); | |
318 | } | |
319 | ||
320 | void | |
321 | privsep_challenge_enable(void) | |
322 | { | |
323 | #ifdef BSD_AUTH | |
324 | extern KbdintDevice mm_bsdauth_device; | |
325 | #endif | |
326 | #ifdef SKEY | |
327 | extern KbdintDevice mm_skey_device; | |
328 | #endif | |
329 | /* As long as SSHv1 has devices[0] hard coded this is fine */ | |
330 | #ifdef BSD_AUTH | |
331 | devices[0] = &mm_bsdauth_device; | |
332 | #else | |
333 | #ifdef SKEY | |
334 | devices[0] = &mm_skey_device; | |
335 | #endif | |
336 | #endif | |
337 | } |