Annotation of src/usr.bin/ssh/auth2.c, Revision 1.166
1.166 ! guenther 1: /* $OpenBSD: auth2.c,v 1.165 2023/03/05 05:34:09 dtucker 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"
1.149 markus 47: #include "sshkey.h"
1.113 deraadt 48: #include "hostfile.h"
1.1 markus 49: #include "auth.h"
50: #include "dispatch.h"
1.29 markus 51: #include "pathnames.h"
1.100 markus 52: #ifdef GSSAPI
53: #include "ssh-gss.h"
54: #endif
1.113 deraadt 55: #include "monitor_wrap.h"
1.143 djm 56: #include "ssherr.h"
1.146 dtucker 57: #include "digest.h"
1.152 djm 58:
1.1 markus 59: /* import */
60: extern ServerOptions options;
61:
1.93 markus 62: /* methods */
63:
64: extern Authmethod method_none;
65: extern Authmethod method_pubkey;
66: extern Authmethod method_passwd;
67: extern Authmethod method_kbdint;
68: extern Authmethod method_hostbased;
1.100 markus 69: #ifdef GSSAPI
70: extern Authmethod method_gssapi;
71: #endif
1.93 markus 72:
73: Authmethod *authmethods[] = {
74: &method_none,
75: &method_pubkey,
1.100 markus 76: #ifdef GSSAPI
77: &method_gssapi,
78: #endif
1.93 markus 79: &method_passwd,
80: &method_kbdint,
81: &method_hostbased,
82: NULL
1.18 markus 83: };
84:
1.1 markus 85: /* protocol */
86:
1.139 markus 87: static int input_service_request(int, u_int32_t, struct ssh *);
88: static int input_userauth_request(int, u_int32_t, struct ssh *);
1.1 markus 89:
90: /* helper */
1.163 djm 91: static Authmethod *authmethod_byname(const char *);
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:
1.135 markus 170: static int
1.139 markus 171: input_service_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 172: {
1.138 markus 173: Authctxt *authctxt = ssh->authctxt;
1.153 djm 174: char *service = NULL;
175: int r, acceptit = 0;
176:
177: if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
178: (r = sshpkt_get_end(ssh)) != 0)
179: goto out;
1.1 markus 180:
1.18 markus 181: if (authctxt == NULL)
182: fatal("input_service_request: no authctxt");
183:
1.1 markus 184: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 185: if (!authctxt->success) {
1.94 deraadt 186: acceptit = 1;
1.1 markus 187: /* now we can handle user-auth requests */
1.153 djm 188: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
189: &input_userauth_request);
1.1 markus 190: }
191: }
192: /* XXX all other service requests are denied */
193:
1.94 deraadt 194: if (acceptit) {
1.153 djm 195: if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
196: (r = sshpkt_put_cstring(ssh, service)) != 0 ||
197: (r = sshpkt_send(ssh)) != 0 ||
198: (r = ssh_packet_write_wait(ssh)) != 0)
199: goto out;
1.1 markus 200: } else {
201: debug("bad service request %s", service);
1.153 djm 202: ssh_packet_disconnect(ssh, "bad service request %s", service);
1.1 markus 203: }
1.153 djm 204: r = 0;
205: out:
1.128 djm 206: free(service);
1.158 markus 207: return r;
1.1 markus 208: }
209:
1.146 dtucker 210: #define MIN_FAIL_DELAY_SECONDS 0.005
211: static double
212: user_specific_delay(const char *user)
213: {
214: char b[512];
215: size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
216: u_char *hash = xmalloc(len);
217: double delay;
218:
1.147 dtucker 219: (void)snprintf(b, sizeof b, "%llu%s",
1.161 djm 220: (unsigned long long)options.timing_secret, user);
1.146 dtucker 221: if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
1.159 djm 222: fatal_f("ssh_digest_memory");
1.146 dtucker 223: /* 0-4.2 ms of delay */
224: delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
225: freezero(hash, len);
1.159 djm 226: debug3_f("user specific delay %0.3lfms", delay/1000);
1.146 dtucker 227: return MIN_FAIL_DELAY_SECONDS + delay;
228: }
229:
230: static void
231: ensure_minimum_time_since(double start, double seconds)
232: {
233: struct timespec ts;
234: double elapsed = monotime_double() - start, req = seconds, remain;
235:
236: /* if we've already passed the requested time, scale up */
237: while ((remain = seconds - elapsed) < 0.0)
238: seconds *= 2;
239:
240: ts.tv_sec = remain;
241: ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
1.159 djm 242: debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
243: elapsed*1000, remain*1000, req*1000);
1.146 dtucker 244: nanosleep(&ts, NULL);
245: }
246:
1.135 markus 247: static int
1.139 markus 248: input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 249: {
1.138 markus 250: Authctxt *authctxt = ssh->authctxt;
1.18 markus 251: Authmethod *m = NULL;
1.153 djm 252: char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
253: int r, authenticated = 0;
1.146 dtucker 254: double tstart = monotime_double();
1.1 markus 255:
1.18 markus 256: if (authctxt == NULL)
257: fatal("input_userauth_request: no authctxt");
1.1 markus 258:
1.153 djm 259: if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
260: (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
261: (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
262: goto out;
1.1 markus 263: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 264: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 265:
1.28 markus 266: if ((style = strchr(user, ':')) != NULL)
267: *style++ = 0;
268:
1.164 djm 269: if (authctxt->attempt >= 1024)
270: auth_maxtries_exceeded(ssh);
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 {
1.164 djm 278: authctxt->valid = 0;
1.137 djm 279: /* Invalid user, fake password information */
1.102 markus 280: authctxt->pw = fakepw();
1.18 markus 281: }
1.137 djm 282: ssh_packet_set_log_preamble(ssh, "%suser %s",
283: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 284: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 285: use_privsep ? " [net]" : "");
1.18 markus 286: authctxt->user = xstrdup(user);
287: authctxt->service = xstrdup(service);
1.62 markus 288: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 289: if (use_privsep)
290: mm_inform_authserv(service, style);
1.153 djm 291: userauth_banner(ssh);
1.125 djm 292: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 293: ssh_packet_disconnect(ssh,
294: "no authentication methods enabled");
1.62 markus 295: } else if (strcmp(user, authctxt->user) != 0 ||
296: strcmp(service, authctxt->service) != 0) {
1.153 djm 297: ssh_packet_disconnect(ssh, "Change of username or service "
298: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 299: authctxt->user, authctxt->service, user, service);
1.1 markus 300: }
1.28 markus 301: /* reset state */
1.140 markus 302: auth2_challenge_stop(ssh);
1.100 markus 303:
304: #ifdef GSSAPI
1.120 djm 305: /* XXX move to auth2_gssapi_stop() */
1.140 markus 306: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
307: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 308: #endif
309:
1.143 djm 310: auth2_authctxt_reset_info(authctxt);
1.28 markus 311: authctxt->postponed = 0;
1.123 djm 312: authctxt->server_caused_failure = 0;
1.18 markus 313:
1.28 markus 314: /* try to authenticate user */
1.125 djm 315: m = authmethod_lookup(authctxt, method);
1.117 djm 316: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 317: debug2("input_userauth_request: try method %s", method);
1.162 djm 318: authenticated = m->userauth(ssh, method);
1.18 markus 319: }
1.146 dtucker 320: if (!authctxt->authenticated)
321: ensure_minimum_time_since(tstart,
322: user_specific_delay(authctxt->user));
1.140 markus 323: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 324: r = 0;
325: out:
1.128 djm 326: free(service);
327: free(user);
328: free(method);
1.153 djm 329: return r;
1.49 markus 330: }
331:
332: void
1.162 djm 333: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 334: const char *submethod)
1.49 markus 335: {
1.140 markus 336: Authctxt *authctxt = ssh->authctxt;
1.162 djm 337: Authmethod *m = NULL;
338: const char *method = packet_method;
1.60 markus 339: char *methods;
1.153 djm 340: int r, partial = 0;
1.60 markus 341:
1.162 djm 342: if (authenticated) {
343: if (!authctxt->valid) {
344: fatal("INTERNAL ERROR: authenticated invalid user %s",
345: authctxt->user);
346: }
347: if (authctxt->postponed)
348: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 349: /* prefer primary authmethod name to possible synonym */
350: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 351: fatal("INTERNAL ERROR: bad method %s", method);
1.163 djm 352: method = m->name;
1.162 djm 353: }
1.18 markus 354:
355: /* Special handling for root */
1.96 markus 356: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 357: !auth_root_allowed(ssh, method))
1.3 markus 358: authenticated = 0;
359:
1.125 djm 360: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 361: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 362: authenticated = 0;
363: partial = 1;
364: }
365: }
1.126 djm 366:
367: /* Log before sending the reply */
1.154 djm 368: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 369:
1.143 djm 370: /* Update information exposed to session */
371: if (authenticated || partial)
372: auth2_update_session_info(authctxt, method, submethod);
373:
1.126 djm 374: if (authctxt->postponed)
375: return;
1.125 djm 376:
1.60 markus 377: if (authenticated == 1) {
378: /* turn off userauth */
1.153 djm 379: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
380: &dispatch_protocol_ignore);
381: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
382: (r = sshpkt_send(ssh)) != 0 ||
383: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 384: fatal_fr(r, "send success packet");
1.60 markus 385: /* now we can break out */
386: authctxt->success = 1;
1.137 djm 387: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 388: } else {
1.119 djm 389: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 390: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 391: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 392: authctxt->failures++;
393: if (authctxt->failures >= options.max_authtries)
1.154 djm 394: auth_maxtries_exceeded(ssh);
1.125 djm 395: methods = authmethods_get(authctxt);
1.159 djm 396: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 397: partial, methods);
1.153 djm 398: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
399: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
400: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
401: (r = sshpkt_send(ssh)) != 0 ||
402: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 403: fatal_fr(r, "send failure packet");
1.128 djm 404: free(methods);
1.60 markus 405: }
1.1 markus 406: }
1.18 markus 407:
1.125 djm 408: /*
409: * Checks whether method is allowed by at least one AuthenticationMethods
410: * methods list. Returns 1 if allowed, or no methods lists configured.
411: * 0 otherwise.
412: */
1.127 markus 413: int
414: auth2_method_allowed(Authctxt *authctxt, const char *method,
415: const char *submethod)
1.125 djm 416: {
417: u_int i;
418:
419: /*
420: * NB. authctxt->num_auth_methods might be zero as a result of
421: * auth2_setup_methods_lists(), so check the configuration.
422: */
423: if (options.num_auth_methods == 0)
424: return 1;
425: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 426: if (list_starts_with(authctxt->auth_methods[i], method,
427: submethod) != MATCH_NONE)
1.125 djm 428: return 1;
429: }
430: return 0;
431: }
432:
1.67 stevesk 433: static char *
1.125 djm 434: authmethods_get(Authctxt *authctxt)
1.1 markus 435: {
1.148 markus 436: struct sshbuf *b;
1.18 markus 437: char *list;
1.148 markus 438: int i, r;
1.1 markus 439:
1.148 markus 440: if ((b = sshbuf_new()) == NULL)
1.159 djm 441: fatal_f("sshbuf_new failed");
1.93 markus 442: for (i = 0; authmethods[i] != NULL; i++) {
443: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 444: continue;
1.125 djm 445: if (authmethods[i]->enabled == NULL ||
446: *(authmethods[i]->enabled) == 0)
447: continue;
1.127 markus 448: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
449: NULL))
1.125 djm 450: continue;
1.148 markus 451: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
452: authmethods[i]->name)) != 0)
1.159 djm 453: fatal_fr(r, "buffer error");
1.1 markus 454: }
1.148 markus 455: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 456: fatal_f("sshbuf_dup_string failed");
1.148 markus 457: sshbuf_free(b);
1.18 markus 458: return list;
459: }
460:
1.66 itojun 461: static Authmethod *
1.163 djm 462: authmethod_byname(const char *name)
1.18 markus 463: {
1.93 markus 464: int i;
465:
1.163 djm 466: if (name == NULL)
467: fatal_f("NULL authentication method name");
468: for (i = 0; authmethods[i] != NULL; i++) {
469: if (strcmp(name, authmethods[i]->name) == 0 ||
470: (authmethods[i]->synonym != NULL &&
471: strcmp(name, authmethods[i]->synonym) == 0))
472: return authmethods[i];
473: }
474: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 475: return NULL;
1.163 djm 476: }
477:
478: static Authmethod *
479: authmethod_lookup(Authctxt *authctxt, const char *name)
480: {
481: Authmethod *method;
482:
483: if ((method = authmethod_byname(name)) == NULL)
484: return NULL;
485:
486: if (method->enabled == NULL || *(method->enabled) == 0) {
487: debug3_f("method %s not enabled", name);
488: return NULL;
489: }
490: if (!auth2_method_allowed(authctxt, method->name, NULL)) {
491: debug3_f("method %s not allowed "
492: "by AuthenticationMethods", name);
493: return NULL;
494: }
495: return method;
1.1 markus 496: }
1.125 djm 497:
498: /*
499: * Check a comma-separated list of methods for validity. Is need_enable is
500: * non-zero, then also require that the methods are enabled.
501: * Returns 0 on success or -1 if the methods list is invalid.
502: */
503: int
504: auth2_methods_valid(const char *_methods, int need_enable)
505: {
1.127 markus 506: char *methods, *omethods, *method, *p;
1.125 djm 507: u_int i, found;
508: int ret = -1;
509:
510: if (*_methods == '\0') {
511: error("empty authentication method list");
512: return -1;
513: }
514: omethods = methods = xstrdup(_methods);
515: while ((method = strsep(&methods, ",")) != NULL) {
516: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 517: if ((p = strchr(method, ':')) != NULL)
518: *p = '\0';
1.125 djm 519: if (strcmp(method, authmethods[i]->name) != 0)
520: continue;
521: if (need_enable) {
522: if (authmethods[i]->enabled == NULL ||
523: *(authmethods[i]->enabled) == 0) {
524: error("Disabled method \"%s\" in "
525: "AuthenticationMethods list \"%s\"",
526: method, _methods);
527: goto out;
528: }
529: }
530: found = 1;
531: break;
532: }
533: if (!found) {
534: error("Unknown authentication method \"%s\" in list",
535: method);
536: goto out;
537: }
538: }
539: ret = 0;
540: out:
541: free(omethods);
542: return ret;
543: }
544:
545: /*
546: * Prune the AuthenticationMethods supplied in the configuration, removing
547: * any methods lists that include disabled methods. Note that this might
548: * leave authctxt->num_auth_methods == 0, even when multiple required auth
549: * has been requested. For this reason, all tests for whether multiple is
550: * enabled should consult options.num_auth_methods directly.
551: */
552: int
553: auth2_setup_methods_lists(Authctxt *authctxt)
554: {
555: u_int i;
1.155 djm 556:
557: /* First, normalise away the "any" pseudo-method */
558: if (options.num_auth_methods == 1 &&
559: strcmp(options.auth_methods[0], "any") == 0) {
560: free(options.auth_methods[0]);
561: options.auth_methods[0] = NULL;
562: options.num_auth_methods = 0;
563: }
1.125 djm 564:
565: if (options.num_auth_methods == 0)
566: return 0;
1.159 djm 567: debug3_f("checking methods");
1.125 djm 568: authctxt->auth_methods = xcalloc(options.num_auth_methods,
569: sizeof(*authctxt->auth_methods));
570: authctxt->num_auth_methods = 0;
571: for (i = 0; i < options.num_auth_methods; i++) {
572: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
573: logit("Authentication methods list \"%s\" contains "
574: "disabled method, skipping",
575: options.auth_methods[i]);
576: continue;
577: }
578: debug("authentication methods list %d: %s",
579: authctxt->num_auth_methods, options.auth_methods[i]);
580: authctxt->auth_methods[authctxt->num_auth_methods++] =
581: xstrdup(options.auth_methods[i]);
582: }
583: if (authctxt->num_auth_methods == 0) {
584: error("No AuthenticationMethods left after eliminating "
585: "disabled methods");
586: return -1;
587: }
588: return 0;
589: }
590:
591: static int
1.127 markus 592: list_starts_with(const char *methods, const char *method,
593: const char *submethod)
1.125 djm 594: {
595: size_t l = strlen(method);
1.127 markus 596: int match;
597: const char *p;
1.125 djm 598:
599: if (strncmp(methods, method, l) != 0)
1.127 markus 600: return MATCH_NONE;
601: p = methods + l;
602: match = MATCH_METHOD;
603: if (*p == ':') {
604: if (!submethod)
605: return MATCH_PARTIAL;
606: l = strlen(submethod);
607: p += 1;
608: if (strncmp(submethod, p, l))
609: return MATCH_NONE;
610: p += l;
611: match = MATCH_BOTH;
612: }
613: if (*p != ',' && *p != '\0')
614: return MATCH_NONE;
615: return match;
1.125 djm 616: }
617:
618: /*
619: * Remove method from the start of a comma-separated list of methods.
620: * Returns 0 if the list of methods did not start with that method or 1
621: * if it did.
622: */
623: static int
1.127 markus 624: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 625: {
1.127 markus 626: char *omethods = *methods, *p;
1.125 djm 627: size_t l = strlen(method);
1.127 markus 628: int match;
1.125 djm 629:
1.127 markus 630: match = list_starts_with(omethods, method, submethod);
631: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 632: return 0;
1.127 markus 633: p = omethods + l;
634: if (submethod && match == MATCH_BOTH)
635: p += 1 + strlen(submethod); /* include colon */
636: if (*p == ',')
637: p++;
638: *methods = xstrdup(p);
1.125 djm 639: free(omethods);
640: return 1;
641: }
642:
643: /*
644: * Called after successful authentication. Will remove the successful method
645: * from the start of each list in which it occurs. If it was the last method
646: * in any list, then authentication is deemed successful.
647: * Returns 1 if the method completed any authentication list or 0 otherwise.
648: */
649: int
1.127 markus 650: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
651: const char *submethod)
1.125 djm 652: {
653: u_int i, found = 0;
654:
1.159 djm 655: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 656: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 657: if (!remove_method(&(authctxt->auth_methods[i]), method,
658: submethod))
1.125 djm 659: continue;
660: found = 1;
661: if (*authctxt->auth_methods[i] == '\0') {
662: debug2("authentication methods list %d complete", i);
663: return 1;
664: }
665: debug3("authentication methods list %d remaining: \"%s\"",
666: i, authctxt->auth_methods[i]);
667: }
668: /* This should not happen, but would be bad if it did */
669: if (!found)
1.159 djm 670: fatal_f("method not in AuthenticationMethods");
1.125 djm 671: return 0;
672: }
673:
1.143 djm 674: /* Reset method-specific information */
675: void auth2_authctxt_reset_info(Authctxt *authctxt)
676: {
677: sshkey_free(authctxt->auth_method_key);
678: free(authctxt->auth_method_info);
679: authctxt->auth_method_key = NULL;
680: authctxt->auth_method_info = NULL;
681: }
682:
683: /* Record auth method-specific information for logs */
684: void
685: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
686: {
687: va_list ap;
1.161 djm 688: int i;
1.143 djm 689:
690: free(authctxt->auth_method_info);
691: authctxt->auth_method_info = NULL;
692:
693: va_start(ap, fmt);
694: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
695: va_end(ap);
696:
1.156 deraadt 697: if (i == -1)
1.159 djm 698: fatal_f("vasprintf failed");
1.143 djm 699: }
700:
701: /*
702: * Records a public key used in authentication. This is used for logging
703: * and to ensure that the same key is not subsequently accepted again for
704: * multiple authentication.
705: */
706: void
707: auth2_record_key(Authctxt *authctxt, int authenticated,
708: const struct sshkey *key)
709: {
710: struct sshkey **tmp, *dup;
711: int r;
712:
1.150 djm 713: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 714: fatal_fr(r, "copy key");
1.143 djm 715: sshkey_free(authctxt->auth_method_key);
716: authctxt->auth_method_key = dup;
717:
718: if (!authenticated)
719: return;
720:
721: /* If authenticated, make sure we don't accept this key again */
1.150 djm 722: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 723: fatal_fr(r, "copy key");
1.143 djm 724: if (authctxt->nprev_keys >= INT_MAX ||
725: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
726: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 727: fatal_f("reallocarray failed");
1.143 djm 728: authctxt->prev_keys = tmp;
729: authctxt->prev_keys[authctxt->nprev_keys] = dup;
730: authctxt->nprev_keys++;
731:
732: }
733:
734: /* Checks whether a key has already been previously used for authentication */
735: int
736: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
737: {
738: u_int i;
739: char *fp;
740:
741: for (i = 0; i < authctxt->nprev_keys; i++) {
742: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
743: fp = sshkey_fingerprint(authctxt->prev_keys[i],
744: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 745: debug3_f("key already used: %s %s",
1.143 djm 746: sshkey_type(authctxt->prev_keys[i]),
747: fp == NULL ? "UNKNOWN" : fp);
748: free(fp);
749: return 1;
750: }
751: }
752: return 0;
753: }
754:
755: /*
756: * Updates authctxt->session_info with details of authentication. Should be
757: * whenever an authentication method succeeds.
758: */
759: void
760: auth2_update_session_info(Authctxt *authctxt, const char *method,
761: const char *submethod)
762: {
763: int r;
764:
765: if (authctxt->session_info == NULL) {
766: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 767: fatal_f("sshbuf_new");
1.143 djm 768: }
769:
770: /* Append method[/submethod] */
771: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
772: method, submethod == NULL ? "" : "/",
773: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 774: fatal_fr(r, "append method");
1.143 djm 775:
776: /* Append key if present */
777: if (authctxt->auth_method_key != NULL) {
778: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
779: (r = sshkey_format_text(authctxt->auth_method_key,
780: authctxt->session_info)) != 0)
1.159 djm 781: fatal_fr(r, "append key");
1.143 djm 782: }
783:
784: if (authctxt->auth_method_info != NULL) {
785: /* Ensure no ambiguity here */
786: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 787: fatal_f("auth_method_info contains \\n");
1.143 djm 788: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
789: (r = sshbuf_putf(authctxt->session_info, "%s",
790: authctxt->auth_method_info)) != 0) {
1.159 djm 791: fatal_fr(r, "append method info");
1.143 djm 792: }
793: }
794: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 795: fatal_fr(r, "append");
1.143 djm 796: }
1.117 djm 797:
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