Annotation of src/usr.bin/ssh/auth2.c, Revision 1.161
1.161 ! djm 1: /* $OpenBSD: auth2.c,v 1.160 2021/01/27 10:05:28 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: */
1.14 deraadt 25:
1.111 stevesk 26: #include <sys/types.h>
1.117 djm 27: #include <sys/stat.h>
28: #include <sys/uio.h>
1.111 stevesk 29:
1.117 djm 30: #include <fcntl.h>
1.143 djm 31: #include <limits.h>
1.111 stevesk 32: #include <pwd.h>
1.121 dtucker 33: #include <stdarg.h>
1.112 stevesk 34: #include <string.h>
1.117 djm 35: #include <unistd.h>
1.151 djm 36: #include <time.h>
1.1 markus 37:
1.157 djm 38: #include "stdlib.h"
1.117 djm 39: #include "atomicio.h"
1.113 deraadt 40: #include "xmalloc.h"
1.32 markus 41: #include "ssh2.h"
1.1 markus 42: #include "packet.h"
1.32 markus 43: #include "log.h"
1.148 markus 44: #include "sshbuf.h"
1.132 millert 45: #include "misc.h"
1.1 markus 46: #include "servconf.h"
47: #include "compat.h"
1.149 markus 48: #include "sshkey.h"
1.113 deraadt 49: #include "hostfile.h"
1.1 markus 50: #include "auth.h"
51: #include "dispatch.h"
1.29 markus 52: #include "pathnames.h"
1.100 markus 53: #ifdef GSSAPI
54: #include "ssh-gss.h"
55: #endif
1.113 deraadt 56: #include "monitor_wrap.h"
1.143 djm 57: #include "ssherr.h"
1.146 dtucker 58: #include "digest.h"
1.152 djm 59:
1.1 markus 60: /* import */
61: extern ServerOptions options;
62:
1.93 markus 63: /* methods */
64:
65: extern Authmethod method_none;
66: extern Authmethod method_pubkey;
67: extern Authmethod method_passwd;
68: extern Authmethod method_kbdint;
69: extern Authmethod method_hostbased;
1.100 markus 70: #ifdef GSSAPI
71: extern Authmethod method_gssapi;
72: #endif
1.93 markus 73:
74: Authmethod *authmethods[] = {
75: &method_none,
76: &method_pubkey,
1.100 markus 77: #ifdef GSSAPI
78: &method_gssapi,
79: #endif
1.93 markus 80: &method_passwd,
81: &method_kbdint,
82: &method_hostbased,
83: NULL
1.18 markus 84: };
85:
1.1 markus 86: /* protocol */
87:
1.139 markus 88: static int input_service_request(int, u_int32_t, struct ssh *);
89: static int input_userauth_request(int, u_int32_t, struct ssh *);
1.1 markus 90:
91: /* helper */
1.125 djm 92: static Authmethod *authmethod_lookup(Authctxt *, const char *);
93: static char *authmethods_get(Authctxt *authctxt);
1.127 markus 94:
95: #define MATCH_NONE 0 /* method or submethod mismatch */
96: #define MATCH_METHOD 1 /* method matches (no submethod specified) */
97: #define MATCH_BOTH 2 /* method and submethod match */
98: #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
99: static int list_starts_with(const char *, const char *, const char *);
1.1 markus 100:
1.117 djm 101: char *
102: auth2_read_banner(void)
103: {
104: struct stat st;
105: char *banner = NULL;
106: size_t len, n;
107: int fd;
108:
109: if ((fd = open(options.banner, O_RDONLY)) == -1)
110: return (NULL);
111: if (fstat(fd, &st) == -1) {
112: close(fd);
113: return (NULL);
114: }
1.124 djm 115: if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
1.117 djm 116: close(fd);
117: return (NULL);
118: }
119:
120: len = (size_t)st.st_size; /* truncate */
121: banner = xmalloc(len + 1);
122: n = atomicio(read, fd, banner, len);
123: close(fd);
124:
125: if (n != len) {
1.128 djm 126: free(banner);
1.117 djm 127: return (NULL);
128: }
129: banner[n] = '\0';
130:
131: return (banner);
132: }
133:
134: static void
1.153 djm 135: userauth_banner(struct ssh *ssh)
1.117 djm 136: {
137: char *banner = NULL;
1.153 djm 138: int r;
1.117 djm 139:
1.144 djm 140: if (options.banner == NULL)
1.117 djm 141: return;
142:
143: if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
144: goto done;
145:
1.153 djm 146: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
147: (r = sshpkt_put_cstring(ssh, banner)) != 0 ||
148: (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
149: (r = sshpkt_send(ssh)) != 0)
1.159 djm 150: fatal_fr(r, "send packet");
1.117 djm 151: debug("userauth_banner: sent");
152: done:
1.128 djm 153: free(banner);
1.117 djm 154: }
155:
1.1 markus 156: /*
1.18 markus 157: * loop until authctxt->success == TRUE
1.1 markus 158: */
1.103 markus 159: void
1.153 djm 160: do_authentication2(struct ssh *ssh)
1.1 markus 161: {
1.153 djm 162: Authctxt *authctxt = ssh->authctxt;
163:
1.140 markus 164: ssh_dispatch_init(ssh, &dispatch_protocol_error);
165: ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.142 markus 166: ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
1.138 markus 167: ssh->authctxt = NULL;
1.1 markus 168: }
169:
1.109 deraadt 170: /*ARGSUSED*/
1.135 markus 171: static int
1.139 markus 172: input_service_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 173: {
1.138 markus 174: Authctxt *authctxt = ssh->authctxt;
1.153 djm 175: char *service = NULL;
176: int r, acceptit = 0;
177:
178: if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
179: (r = sshpkt_get_end(ssh)) != 0)
180: goto out;
1.1 markus 181:
1.18 markus 182: if (authctxt == NULL)
183: fatal("input_service_request: no authctxt");
184:
1.1 markus 185: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 186: if (!authctxt->success) {
1.94 deraadt 187: acceptit = 1;
1.1 markus 188: /* now we can handle user-auth requests */
1.153 djm 189: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
190: &input_userauth_request);
1.1 markus 191: }
192: }
193: /* XXX all other service requests are denied */
194:
1.94 deraadt 195: if (acceptit) {
1.153 djm 196: if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
197: (r = sshpkt_put_cstring(ssh, service)) != 0 ||
198: (r = sshpkt_send(ssh)) != 0 ||
199: (r = ssh_packet_write_wait(ssh)) != 0)
200: goto out;
1.1 markus 201: } else {
202: debug("bad service request %s", service);
1.153 djm 203: ssh_packet_disconnect(ssh, "bad service request %s", service);
1.1 markus 204: }
1.153 djm 205: r = 0;
206: out:
1.128 djm 207: free(service);
1.158 markus 208: return r;
1.1 markus 209: }
210:
1.146 dtucker 211: #define MIN_FAIL_DELAY_SECONDS 0.005
212: static double
213: user_specific_delay(const char *user)
214: {
215: char b[512];
216: size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
217: u_char *hash = xmalloc(len);
218: double delay;
219:
1.147 dtucker 220: (void)snprintf(b, sizeof b, "%llu%s",
1.161 ! djm 221: (unsigned long long)options.timing_secret, user);
1.146 dtucker 222: if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
1.159 djm 223: fatal_f("ssh_digest_memory");
1.146 dtucker 224: /* 0-4.2 ms of delay */
225: delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
226: freezero(hash, len);
1.159 djm 227: debug3_f("user specific delay %0.3lfms", delay/1000);
1.146 dtucker 228: return MIN_FAIL_DELAY_SECONDS + delay;
229: }
230:
231: static void
232: ensure_minimum_time_since(double start, double seconds)
233: {
234: struct timespec ts;
235: double elapsed = monotime_double() - start, req = seconds, remain;
236:
237: /* if we've already passed the requested time, scale up */
238: while ((remain = seconds - elapsed) < 0.0)
239: seconds *= 2;
240:
241: ts.tv_sec = remain;
242: ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
1.159 djm 243: debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
244: elapsed*1000, remain*1000, req*1000);
1.146 dtucker 245: nanosleep(&ts, NULL);
246: }
247:
1.109 deraadt 248: /*ARGSUSED*/
1.135 markus 249: static int
1.139 markus 250: input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 251: {
1.138 markus 252: Authctxt *authctxt = ssh->authctxt;
1.18 markus 253: Authmethod *m = NULL;
1.153 djm 254: char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
255: int r, authenticated = 0;
1.146 dtucker 256: double tstart = monotime_double();
1.1 markus 257:
1.18 markus 258: if (authctxt == NULL)
259: fatal("input_userauth_request: no authctxt");
1.1 markus 260:
1.153 djm 261: if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
262: (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
263: (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
264: goto out;
1.1 markus 265: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 266: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 267:
1.28 markus 268: if ((style = strchr(user, ':')) != NULL)
269: *style++ = 0;
270:
1.36 stevesk 271: if (authctxt->attempt++ == 0) {
1.18 markus 272: /* setup auth context */
1.154 djm 273: authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
1.89 markus 274: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 275: authctxt->valid = 1;
1.159 djm 276: debug2_f("setting up authctxt for %s", user);
1.18 markus 277: } else {
1.137 djm 278: /* Invalid user, fake password information */
1.102 markus 279: authctxt->pw = fakepw();
1.18 markus 280: }
1.137 djm 281: ssh_packet_set_log_preamble(ssh, "%suser %s",
282: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 283: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 284: use_privsep ? " [net]" : "");
1.18 markus 285: authctxt->user = xstrdup(user);
286: authctxt->service = xstrdup(service);
1.62 markus 287: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 288: if (use_privsep)
289: mm_inform_authserv(service, style);
1.153 djm 290: userauth_banner(ssh);
1.125 djm 291: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 292: ssh_packet_disconnect(ssh,
293: "no authentication methods enabled");
1.62 markus 294: } else if (strcmp(user, authctxt->user) != 0 ||
295: strcmp(service, authctxt->service) != 0) {
1.153 djm 296: ssh_packet_disconnect(ssh, "Change of username or service "
297: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 298: authctxt->user, authctxt->service, user, service);
1.1 markus 299: }
1.28 markus 300: /* reset state */
1.140 markus 301: auth2_challenge_stop(ssh);
1.100 markus 302:
303: #ifdef GSSAPI
1.120 djm 304: /* XXX move to auth2_gssapi_stop() */
1.140 markus 305: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
306: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 307: #endif
308:
1.143 djm 309: auth2_authctxt_reset_info(authctxt);
1.28 markus 310: authctxt->postponed = 0;
1.123 djm 311: authctxt->server_caused_failure = 0;
1.18 markus 312:
1.28 markus 313: /* try to authenticate user */
1.125 djm 314: m = authmethod_lookup(authctxt, method);
1.117 djm 315: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 316: debug2("input_userauth_request: try method %s", method);
1.140 markus 317: authenticated = m->userauth(ssh);
1.18 markus 318: }
1.146 dtucker 319: if (!authctxt->authenticated)
320: ensure_minimum_time_since(tstart,
321: user_specific_delay(authctxt->user));
1.140 markus 322: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 323: r = 0;
324: out:
1.128 djm 325: free(service);
326: free(user);
327: free(method);
1.153 djm 328: return r;
1.49 markus 329: }
330:
331: void
1.140 markus 332: userauth_finish(struct ssh *ssh, int authenticated, const char *method,
1.126 djm 333: const char *submethod)
1.49 markus 334: {
1.140 markus 335: Authctxt *authctxt = ssh->authctxt;
1.60 markus 336: char *methods;
1.153 djm 337: int r, partial = 0;
1.60 markus 338:
1.28 markus 339: if (!authctxt->valid && authenticated)
340: fatal("INTERNAL ERROR: authenticated invalid user %s",
341: authctxt->user);
1.126 djm 342: if (authenticated && authctxt->postponed)
343: fatal("INTERNAL ERROR: authenticated and postponed");
1.18 markus 344:
345: /* Special handling for root */
1.96 markus 346: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 347: !auth_root_allowed(ssh, method))
1.3 markus 348: authenticated = 0;
349:
1.125 djm 350: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 351: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 352: authenticated = 0;
353: partial = 1;
354: }
355: }
1.126 djm 356:
357: /* Log before sending the reply */
1.154 djm 358: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 359:
1.143 djm 360: /* Update information exposed to session */
361: if (authenticated || partial)
362: auth2_update_session_info(authctxt, method, submethod);
363:
1.126 djm 364: if (authctxt->postponed)
365: return;
1.125 djm 366:
1.60 markus 367: if (authenticated == 1) {
368: /* turn off userauth */
1.153 djm 369: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
370: &dispatch_protocol_ignore);
371: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
372: (r = sshpkt_send(ssh)) != 0 ||
373: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 374: fatal_fr(r, "send success packet");
1.60 markus 375: /* now we can break out */
376: authctxt->success = 1;
1.137 djm 377: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 378: } else {
1.119 djm 379: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 380: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 381: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 382: authctxt->failures++;
383: if (authctxt->failures >= options.max_authtries)
1.154 djm 384: auth_maxtries_exceeded(ssh);
1.125 djm 385: methods = authmethods_get(authctxt);
1.159 djm 386: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 387: partial, methods);
1.153 djm 388: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
389: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
390: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
391: (r = sshpkt_send(ssh)) != 0 ||
392: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 393: fatal_fr(r, "send failure packet");
1.128 djm 394: free(methods);
1.60 markus 395: }
1.1 markus 396: }
1.18 markus 397:
1.125 djm 398: /*
399: * Checks whether method is allowed by at least one AuthenticationMethods
400: * methods list. Returns 1 if allowed, or no methods lists configured.
401: * 0 otherwise.
402: */
1.127 markus 403: int
404: auth2_method_allowed(Authctxt *authctxt, const char *method,
405: const char *submethod)
1.125 djm 406: {
407: u_int i;
408:
409: /*
410: * NB. authctxt->num_auth_methods might be zero as a result of
411: * auth2_setup_methods_lists(), so check the configuration.
412: */
413: if (options.num_auth_methods == 0)
414: return 1;
415: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 416: if (list_starts_with(authctxt->auth_methods[i], method,
417: submethod) != MATCH_NONE)
1.125 djm 418: return 1;
419: }
420: return 0;
421: }
422:
1.67 stevesk 423: static char *
1.125 djm 424: authmethods_get(Authctxt *authctxt)
1.1 markus 425: {
1.148 markus 426: struct sshbuf *b;
1.18 markus 427: char *list;
1.148 markus 428: int i, r;
1.1 markus 429:
1.148 markus 430: if ((b = sshbuf_new()) == NULL)
1.159 djm 431: fatal_f("sshbuf_new failed");
1.93 markus 432: for (i = 0; authmethods[i] != NULL; i++) {
433: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 434: continue;
1.125 djm 435: if (authmethods[i]->enabled == NULL ||
436: *(authmethods[i]->enabled) == 0)
437: continue;
1.127 markus 438: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
439: NULL))
1.125 djm 440: continue;
1.148 markus 441: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
442: authmethods[i]->name)) != 0)
1.159 djm 443: fatal_fr(r, "buffer error");
1.1 markus 444: }
1.148 markus 445: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 446: fatal_f("sshbuf_dup_string failed");
1.148 markus 447: sshbuf_free(b);
1.18 markus 448: return list;
449: }
450:
1.66 itojun 451: static Authmethod *
1.125 djm 452: authmethod_lookup(Authctxt *authctxt, const char *name)
1.18 markus 453: {
1.93 markus 454: int i;
455:
1.18 markus 456: if (name != NULL)
1.93 markus 457: for (i = 0; authmethods[i] != NULL; i++)
458: if (authmethods[i]->enabled != NULL &&
459: *(authmethods[i]->enabled) != 0 &&
1.125 djm 460: strcmp(name, authmethods[i]->name) == 0 &&
1.127 markus 461: auth2_method_allowed(authctxt,
462: authmethods[i]->name, NULL))
1.93 markus 463: return authmethods[i];
464: debug2("Unrecognized authentication method name: %s",
465: name ? name : "NULL");
1.18 markus 466: return NULL;
1.1 markus 467: }
1.125 djm 468:
469: /*
470: * Check a comma-separated list of methods for validity. Is need_enable is
471: * non-zero, then also require that the methods are enabled.
472: * Returns 0 on success or -1 if the methods list is invalid.
473: */
474: int
475: auth2_methods_valid(const char *_methods, int need_enable)
476: {
1.127 markus 477: char *methods, *omethods, *method, *p;
1.125 djm 478: u_int i, found;
479: int ret = -1;
480:
481: if (*_methods == '\0') {
482: error("empty authentication method list");
483: return -1;
484: }
485: omethods = methods = xstrdup(_methods);
486: while ((method = strsep(&methods, ",")) != NULL) {
487: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 488: if ((p = strchr(method, ':')) != NULL)
489: *p = '\0';
1.125 djm 490: if (strcmp(method, authmethods[i]->name) != 0)
491: continue;
492: if (need_enable) {
493: if (authmethods[i]->enabled == NULL ||
494: *(authmethods[i]->enabled) == 0) {
495: error("Disabled method \"%s\" in "
496: "AuthenticationMethods list \"%s\"",
497: method, _methods);
498: goto out;
499: }
500: }
501: found = 1;
502: break;
503: }
504: if (!found) {
505: error("Unknown authentication method \"%s\" in list",
506: method);
507: goto out;
508: }
509: }
510: ret = 0;
511: out:
512: free(omethods);
513: return ret;
514: }
515:
516: /*
517: * Prune the AuthenticationMethods supplied in the configuration, removing
518: * any methods lists that include disabled methods. Note that this might
519: * leave authctxt->num_auth_methods == 0, even when multiple required auth
520: * has been requested. For this reason, all tests for whether multiple is
521: * enabled should consult options.num_auth_methods directly.
522: */
523: int
524: auth2_setup_methods_lists(Authctxt *authctxt)
525: {
526: u_int i;
1.155 djm 527:
528: /* First, normalise away the "any" pseudo-method */
529: if (options.num_auth_methods == 1 &&
530: strcmp(options.auth_methods[0], "any") == 0) {
531: free(options.auth_methods[0]);
532: options.auth_methods[0] = NULL;
533: options.num_auth_methods = 0;
534: }
1.125 djm 535:
536: if (options.num_auth_methods == 0)
537: return 0;
1.159 djm 538: debug3_f("checking methods");
1.125 djm 539: authctxt->auth_methods = xcalloc(options.num_auth_methods,
540: sizeof(*authctxt->auth_methods));
541: authctxt->num_auth_methods = 0;
542: for (i = 0; i < options.num_auth_methods; i++) {
543: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
544: logit("Authentication methods list \"%s\" contains "
545: "disabled method, skipping",
546: options.auth_methods[i]);
547: continue;
548: }
549: debug("authentication methods list %d: %s",
550: authctxt->num_auth_methods, options.auth_methods[i]);
551: authctxt->auth_methods[authctxt->num_auth_methods++] =
552: xstrdup(options.auth_methods[i]);
553: }
554: if (authctxt->num_auth_methods == 0) {
555: error("No AuthenticationMethods left after eliminating "
556: "disabled methods");
557: return -1;
558: }
559: return 0;
560: }
561:
562: static int
1.127 markus 563: list_starts_with(const char *methods, const char *method,
564: const char *submethod)
1.125 djm 565: {
566: size_t l = strlen(method);
1.127 markus 567: int match;
568: const char *p;
1.125 djm 569:
570: if (strncmp(methods, method, l) != 0)
1.127 markus 571: return MATCH_NONE;
572: p = methods + l;
573: match = MATCH_METHOD;
574: if (*p == ':') {
575: if (!submethod)
576: return MATCH_PARTIAL;
577: l = strlen(submethod);
578: p += 1;
579: if (strncmp(submethod, p, l))
580: return MATCH_NONE;
581: p += l;
582: match = MATCH_BOTH;
583: }
584: if (*p != ',' && *p != '\0')
585: return MATCH_NONE;
586: return match;
1.125 djm 587: }
588:
589: /*
590: * Remove method from the start of a comma-separated list of methods.
591: * Returns 0 if the list of methods did not start with that method or 1
592: * if it did.
593: */
594: static int
1.127 markus 595: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 596: {
1.127 markus 597: char *omethods = *methods, *p;
1.125 djm 598: size_t l = strlen(method);
1.127 markus 599: int match;
1.125 djm 600:
1.127 markus 601: match = list_starts_with(omethods, method, submethod);
602: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 603: return 0;
1.127 markus 604: p = omethods + l;
605: if (submethod && match == MATCH_BOTH)
606: p += 1 + strlen(submethod); /* include colon */
607: if (*p == ',')
608: p++;
609: *methods = xstrdup(p);
1.125 djm 610: free(omethods);
611: return 1;
612: }
613:
614: /*
615: * Called after successful authentication. Will remove the successful method
616: * from the start of each list in which it occurs. If it was the last method
617: * in any list, then authentication is deemed successful.
618: * Returns 1 if the method completed any authentication list or 0 otherwise.
619: */
620: int
1.127 markus 621: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
622: const char *submethod)
1.125 djm 623: {
624: u_int i, found = 0;
625:
1.159 djm 626: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 627: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 628: if (!remove_method(&(authctxt->auth_methods[i]), method,
629: submethod))
1.125 djm 630: continue;
631: found = 1;
632: if (*authctxt->auth_methods[i] == '\0') {
633: debug2("authentication methods list %d complete", i);
634: return 1;
635: }
636: debug3("authentication methods list %d remaining: \"%s\"",
637: i, authctxt->auth_methods[i]);
638: }
639: /* This should not happen, but would be bad if it did */
640: if (!found)
1.159 djm 641: fatal_f("method not in AuthenticationMethods");
1.125 djm 642: return 0;
643: }
644:
1.143 djm 645: /* Reset method-specific information */
646: void auth2_authctxt_reset_info(Authctxt *authctxt)
647: {
648: sshkey_free(authctxt->auth_method_key);
649: free(authctxt->auth_method_info);
650: authctxt->auth_method_key = NULL;
651: authctxt->auth_method_info = NULL;
652: }
653:
654: /* Record auth method-specific information for logs */
655: void
656: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
657: {
658: va_list ap;
1.161 ! djm 659: int i;
1.143 djm 660:
661: free(authctxt->auth_method_info);
662: authctxt->auth_method_info = NULL;
663:
664: va_start(ap, fmt);
665: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
666: va_end(ap);
667:
1.156 deraadt 668: if (i == -1)
1.159 djm 669: fatal_f("vasprintf failed");
1.143 djm 670: }
671:
672: /*
673: * Records a public key used in authentication. This is used for logging
674: * and to ensure that the same key is not subsequently accepted again for
675: * multiple authentication.
676: */
677: void
678: auth2_record_key(Authctxt *authctxt, int authenticated,
679: const struct sshkey *key)
680: {
681: struct sshkey **tmp, *dup;
682: int r;
683:
1.150 djm 684: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 685: fatal_fr(r, "copy key");
1.143 djm 686: sshkey_free(authctxt->auth_method_key);
687: authctxt->auth_method_key = dup;
688:
689: if (!authenticated)
690: return;
691:
692: /* If authenticated, make sure we don't accept this key again */
1.150 djm 693: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 694: fatal_fr(r, "copy key");
1.143 djm 695: if (authctxt->nprev_keys >= INT_MAX ||
696: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
697: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 698: fatal_f("reallocarray failed");
1.143 djm 699: authctxt->prev_keys = tmp;
700: authctxt->prev_keys[authctxt->nprev_keys] = dup;
701: authctxt->nprev_keys++;
702:
703: }
704:
705: /* Checks whether a key has already been previously used for authentication */
706: int
707: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
708: {
709: u_int i;
710: char *fp;
711:
712: for (i = 0; i < authctxt->nprev_keys; i++) {
713: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
714: fp = sshkey_fingerprint(authctxt->prev_keys[i],
715: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 716: debug3_f("key already used: %s %s",
1.143 djm 717: sshkey_type(authctxt->prev_keys[i]),
718: fp == NULL ? "UNKNOWN" : fp);
719: free(fp);
720: return 1;
721: }
722: }
723: return 0;
724: }
725:
726: /*
727: * Updates authctxt->session_info with details of authentication. Should be
728: * whenever an authentication method succeeds.
729: */
730: void
731: auth2_update_session_info(Authctxt *authctxt, const char *method,
732: const char *submethod)
733: {
734: int r;
735:
736: if (authctxt->session_info == NULL) {
737: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 738: fatal_f("sshbuf_new");
1.143 djm 739: }
740:
741: /* Append method[/submethod] */
742: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
743: method, submethod == NULL ? "" : "/",
744: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 745: fatal_fr(r, "append method");
1.143 djm 746:
747: /* Append key if present */
748: if (authctxt->auth_method_key != NULL) {
749: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
750: (r = sshkey_format_text(authctxt->auth_method_key,
751: authctxt->session_info)) != 0)
1.159 djm 752: fatal_fr(r, "append key");
1.143 djm 753: }
754:
755: if (authctxt->auth_method_info != NULL) {
756: /* Ensure no ambiguity here */
757: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 758: fatal_f("auth_method_info contains \\n");
1.143 djm 759: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
760: (r = sshbuf_putf(authctxt->session_info, "%s",
761: authctxt->auth_method_info)) != 0) {
1.159 djm 762: fatal_fr(r, "append method info");
1.143 djm 763: }
764: }
765: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 766: fatal_fr(r, "append");
1.143 djm 767: }
1.117 djm 768:
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