Annotation of src/usr.bin/ssh/auth2.c, Revision 1.165
1.165 ! dtucker 1: /* $OpenBSD: auth2.c,v 1.164 2022/02/23 11:18:13 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"
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:
1.109 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:
1.164 djm 271: if (authctxt->attempt >= 1024)
272: auth_maxtries_exceeded(ssh);
1.36 stevesk 273: if (authctxt->attempt++ == 0) {
1.18 markus 274: /* setup auth context */
1.154 djm 275: authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
1.89 markus 276: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 277: authctxt->valid = 1;
1.159 djm 278: debug2_f("setting up authctxt for %s", user);
1.18 markus 279: } else {
1.164 djm 280: authctxt->valid = 0;
1.137 djm 281: /* Invalid user, fake password information */
1.102 markus 282: authctxt->pw = fakepw();
1.18 markus 283: }
1.137 djm 284: ssh_packet_set_log_preamble(ssh, "%suser %s",
285: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 286: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 287: use_privsep ? " [net]" : "");
1.18 markus 288: authctxt->user = xstrdup(user);
289: authctxt->service = xstrdup(service);
1.62 markus 290: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 291: if (use_privsep)
292: mm_inform_authserv(service, style);
1.153 djm 293: userauth_banner(ssh);
1.125 djm 294: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 295: ssh_packet_disconnect(ssh,
296: "no authentication methods enabled");
1.62 markus 297: } else if (strcmp(user, authctxt->user) != 0 ||
298: strcmp(service, authctxt->service) != 0) {
1.153 djm 299: ssh_packet_disconnect(ssh, "Change of username or service "
300: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 301: authctxt->user, authctxt->service, user, service);
1.1 markus 302: }
1.28 markus 303: /* reset state */
1.140 markus 304: auth2_challenge_stop(ssh);
1.100 markus 305:
306: #ifdef GSSAPI
1.120 djm 307: /* XXX move to auth2_gssapi_stop() */
1.140 markus 308: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
309: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 310: #endif
311:
1.143 djm 312: auth2_authctxt_reset_info(authctxt);
1.28 markus 313: authctxt->postponed = 0;
1.123 djm 314: authctxt->server_caused_failure = 0;
1.18 markus 315:
1.28 markus 316: /* try to authenticate user */
1.125 djm 317: m = authmethod_lookup(authctxt, method);
1.117 djm 318: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 319: debug2("input_userauth_request: try method %s", method);
1.162 djm 320: authenticated = m->userauth(ssh, method);
1.18 markus 321: }
1.146 dtucker 322: if (!authctxt->authenticated)
323: ensure_minimum_time_since(tstart,
324: user_specific_delay(authctxt->user));
1.140 markus 325: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 326: r = 0;
327: out:
1.128 djm 328: free(service);
329: free(user);
330: free(method);
1.153 djm 331: return r;
1.49 markus 332: }
333:
334: void
1.162 djm 335: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 336: const char *submethod)
1.49 markus 337: {
1.140 markus 338: Authctxt *authctxt = ssh->authctxt;
1.162 djm 339: Authmethod *m = NULL;
340: const char *method = packet_method;
1.60 markus 341: char *methods;
1.153 djm 342: int r, partial = 0;
1.60 markus 343:
1.162 djm 344: if (authenticated) {
345: if (!authctxt->valid) {
346: fatal("INTERNAL ERROR: authenticated invalid user %s",
347: authctxt->user);
348: }
349: if (authctxt->postponed)
350: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 351: /* prefer primary authmethod name to possible synonym */
352: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 353: fatal("INTERNAL ERROR: bad method %s", method);
1.163 djm 354: method = m->name;
1.162 djm 355: }
1.18 markus 356:
357: /* Special handling for root */
1.96 markus 358: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 359: !auth_root_allowed(ssh, method))
1.3 markus 360: authenticated = 0;
361:
1.125 djm 362: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 363: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 364: authenticated = 0;
365: partial = 1;
366: }
367: }
1.126 djm 368:
369: /* Log before sending the reply */
1.154 djm 370: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 371:
1.143 djm 372: /* Update information exposed to session */
373: if (authenticated || partial)
374: auth2_update_session_info(authctxt, method, submethod);
375:
1.126 djm 376: if (authctxt->postponed)
377: return;
1.125 djm 378:
1.60 markus 379: if (authenticated == 1) {
380: /* turn off userauth */
1.153 djm 381: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
382: &dispatch_protocol_ignore);
383: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
384: (r = sshpkt_send(ssh)) != 0 ||
385: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 386: fatal_fr(r, "send success packet");
1.60 markus 387: /* now we can break out */
388: authctxt->success = 1;
1.137 djm 389: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 390: } else {
1.119 djm 391: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 392: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 393: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 394: authctxt->failures++;
395: if (authctxt->failures >= options.max_authtries)
1.154 djm 396: auth_maxtries_exceeded(ssh);
1.125 djm 397: methods = authmethods_get(authctxt);
1.159 djm 398: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 399: partial, methods);
1.153 djm 400: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
401: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
402: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
403: (r = sshpkt_send(ssh)) != 0 ||
404: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 405: fatal_fr(r, "send failure packet");
1.128 djm 406: free(methods);
1.60 markus 407: }
1.1 markus 408: }
1.18 markus 409:
1.125 djm 410: /*
411: * Checks whether method is allowed by at least one AuthenticationMethods
412: * methods list. Returns 1 if allowed, or no methods lists configured.
413: * 0 otherwise.
414: */
1.127 markus 415: int
416: auth2_method_allowed(Authctxt *authctxt, const char *method,
417: const char *submethod)
1.125 djm 418: {
419: u_int i;
420:
421: /*
422: * NB. authctxt->num_auth_methods might be zero as a result of
423: * auth2_setup_methods_lists(), so check the configuration.
424: */
425: if (options.num_auth_methods == 0)
426: return 1;
427: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 428: if (list_starts_with(authctxt->auth_methods[i], method,
429: submethod) != MATCH_NONE)
1.125 djm 430: return 1;
431: }
432: return 0;
433: }
434:
1.67 stevesk 435: static char *
1.125 djm 436: authmethods_get(Authctxt *authctxt)
1.1 markus 437: {
1.148 markus 438: struct sshbuf *b;
1.18 markus 439: char *list;
1.148 markus 440: int i, r;
1.1 markus 441:
1.148 markus 442: if ((b = sshbuf_new()) == NULL)
1.159 djm 443: fatal_f("sshbuf_new failed");
1.93 markus 444: for (i = 0; authmethods[i] != NULL; i++) {
445: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 446: continue;
1.125 djm 447: if (authmethods[i]->enabled == NULL ||
448: *(authmethods[i]->enabled) == 0)
449: continue;
1.127 markus 450: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
451: NULL))
1.125 djm 452: continue;
1.148 markus 453: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
454: authmethods[i]->name)) != 0)
1.159 djm 455: fatal_fr(r, "buffer error");
1.1 markus 456: }
1.148 markus 457: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 458: fatal_f("sshbuf_dup_string failed");
1.148 markus 459: sshbuf_free(b);
1.18 markus 460: return list;
461: }
462:
1.66 itojun 463: static Authmethod *
1.163 djm 464: authmethod_byname(const char *name)
1.18 markus 465: {
1.93 markus 466: int i;
467:
1.163 djm 468: if (name == NULL)
469: fatal_f("NULL authentication method name");
470: for (i = 0; authmethods[i] != NULL; i++) {
471: if (strcmp(name, authmethods[i]->name) == 0 ||
472: (authmethods[i]->synonym != NULL &&
473: strcmp(name, authmethods[i]->synonym) == 0))
474: return authmethods[i];
475: }
476: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 477: return NULL;
1.163 djm 478: }
479:
480: static Authmethod *
481: authmethod_lookup(Authctxt *authctxt, const char *name)
482: {
483: Authmethod *method;
484:
485: if ((method = authmethod_byname(name)) == NULL)
486: return NULL;
487:
488: if (method->enabled == NULL || *(method->enabled) == 0) {
489: debug3_f("method %s not enabled", name);
490: return NULL;
491: }
492: if (!auth2_method_allowed(authctxt, method->name, NULL)) {
493: debug3_f("method %s not allowed "
494: "by AuthenticationMethods", name);
495: return NULL;
496: }
497: return method;
1.1 markus 498: }
1.125 djm 499:
500: /*
501: * Check a comma-separated list of methods for validity. Is need_enable is
502: * non-zero, then also require that the methods are enabled.
503: * Returns 0 on success or -1 if the methods list is invalid.
504: */
505: int
506: auth2_methods_valid(const char *_methods, int need_enable)
507: {
1.127 markus 508: char *methods, *omethods, *method, *p;
1.125 djm 509: u_int i, found;
510: int ret = -1;
511:
512: if (*_methods == '\0') {
513: error("empty authentication method list");
514: return -1;
515: }
516: omethods = methods = xstrdup(_methods);
517: while ((method = strsep(&methods, ",")) != NULL) {
518: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 519: if ((p = strchr(method, ':')) != NULL)
520: *p = '\0';
1.125 djm 521: if (strcmp(method, authmethods[i]->name) != 0)
522: continue;
523: if (need_enable) {
524: if (authmethods[i]->enabled == NULL ||
525: *(authmethods[i]->enabled) == 0) {
526: error("Disabled method \"%s\" in "
527: "AuthenticationMethods list \"%s\"",
528: method, _methods);
529: goto out;
530: }
531: }
532: found = 1;
533: break;
534: }
535: if (!found) {
536: error("Unknown authentication method \"%s\" in list",
537: method);
538: goto out;
539: }
540: }
541: ret = 0;
542: out:
543: free(omethods);
544: return ret;
545: }
546:
547: /*
548: * Prune the AuthenticationMethods supplied in the configuration, removing
549: * any methods lists that include disabled methods. Note that this might
550: * leave authctxt->num_auth_methods == 0, even when multiple required auth
551: * has been requested. For this reason, all tests for whether multiple is
552: * enabled should consult options.num_auth_methods directly.
553: */
554: int
555: auth2_setup_methods_lists(Authctxt *authctxt)
556: {
557: u_int i;
1.155 djm 558:
559: /* First, normalise away the "any" pseudo-method */
560: if (options.num_auth_methods == 1 &&
561: strcmp(options.auth_methods[0], "any") == 0) {
562: free(options.auth_methods[0]);
563: options.auth_methods[0] = NULL;
564: options.num_auth_methods = 0;
565: }
1.125 djm 566:
567: if (options.num_auth_methods == 0)
568: return 0;
1.159 djm 569: debug3_f("checking methods");
1.125 djm 570: authctxt->auth_methods = xcalloc(options.num_auth_methods,
571: sizeof(*authctxt->auth_methods));
572: authctxt->num_auth_methods = 0;
573: for (i = 0; i < options.num_auth_methods; i++) {
574: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
575: logit("Authentication methods list \"%s\" contains "
576: "disabled method, skipping",
577: options.auth_methods[i]);
578: continue;
579: }
580: debug("authentication methods list %d: %s",
581: authctxt->num_auth_methods, options.auth_methods[i]);
582: authctxt->auth_methods[authctxt->num_auth_methods++] =
583: xstrdup(options.auth_methods[i]);
584: }
585: if (authctxt->num_auth_methods == 0) {
586: error("No AuthenticationMethods left after eliminating "
587: "disabled methods");
588: return -1;
589: }
590: return 0;
591: }
592:
593: static int
1.127 markus 594: list_starts_with(const char *methods, const char *method,
595: const char *submethod)
1.125 djm 596: {
597: size_t l = strlen(method);
1.127 markus 598: int match;
599: const char *p;
1.125 djm 600:
601: if (strncmp(methods, method, l) != 0)
1.127 markus 602: return MATCH_NONE;
603: p = methods + l;
604: match = MATCH_METHOD;
605: if (*p == ':') {
606: if (!submethod)
607: return MATCH_PARTIAL;
608: l = strlen(submethod);
609: p += 1;
610: if (strncmp(submethod, p, l))
611: return MATCH_NONE;
612: p += l;
613: match = MATCH_BOTH;
614: }
615: if (*p != ',' && *p != '\0')
616: return MATCH_NONE;
617: return match;
1.125 djm 618: }
619:
620: /*
621: * Remove method from the start of a comma-separated list of methods.
622: * Returns 0 if the list of methods did not start with that method or 1
623: * if it did.
624: */
625: static int
1.127 markus 626: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 627: {
1.127 markus 628: char *omethods = *methods, *p;
1.125 djm 629: size_t l = strlen(method);
1.127 markus 630: int match;
1.125 djm 631:
1.127 markus 632: match = list_starts_with(omethods, method, submethod);
633: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 634: return 0;
1.127 markus 635: p = omethods + l;
636: if (submethod && match == MATCH_BOTH)
637: p += 1 + strlen(submethod); /* include colon */
638: if (*p == ',')
639: p++;
640: *methods = xstrdup(p);
1.125 djm 641: free(omethods);
642: return 1;
643: }
644:
645: /*
646: * Called after successful authentication. Will remove the successful method
647: * from the start of each list in which it occurs. If it was the last method
648: * in any list, then authentication is deemed successful.
649: * Returns 1 if the method completed any authentication list or 0 otherwise.
650: */
651: int
1.127 markus 652: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
653: const char *submethod)
1.125 djm 654: {
655: u_int i, found = 0;
656:
1.159 djm 657: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 658: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 659: if (!remove_method(&(authctxt->auth_methods[i]), method,
660: submethod))
1.125 djm 661: continue;
662: found = 1;
663: if (*authctxt->auth_methods[i] == '\0') {
664: debug2("authentication methods list %d complete", i);
665: return 1;
666: }
667: debug3("authentication methods list %d remaining: \"%s\"",
668: i, authctxt->auth_methods[i]);
669: }
670: /* This should not happen, but would be bad if it did */
671: if (!found)
1.159 djm 672: fatal_f("method not in AuthenticationMethods");
1.125 djm 673: return 0;
674: }
675:
1.143 djm 676: /* Reset method-specific information */
677: void auth2_authctxt_reset_info(Authctxt *authctxt)
678: {
679: sshkey_free(authctxt->auth_method_key);
680: free(authctxt->auth_method_info);
681: authctxt->auth_method_key = NULL;
682: authctxt->auth_method_info = NULL;
683: }
684:
685: /* Record auth method-specific information for logs */
686: void
687: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
688: {
689: va_list ap;
1.161 djm 690: int i;
1.143 djm 691:
692: free(authctxt->auth_method_info);
693: authctxt->auth_method_info = NULL;
694:
695: va_start(ap, fmt);
696: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
697: va_end(ap);
698:
1.156 deraadt 699: if (i == -1)
1.159 djm 700: fatal_f("vasprintf failed");
1.143 djm 701: }
702:
703: /*
704: * Records a public key used in authentication. This is used for logging
705: * and to ensure that the same key is not subsequently accepted again for
706: * multiple authentication.
707: */
708: void
709: auth2_record_key(Authctxt *authctxt, int authenticated,
710: const struct sshkey *key)
711: {
712: struct sshkey **tmp, *dup;
713: int r;
714:
1.150 djm 715: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 716: fatal_fr(r, "copy key");
1.143 djm 717: sshkey_free(authctxt->auth_method_key);
718: authctxt->auth_method_key = dup;
719:
720: if (!authenticated)
721: return;
722:
723: /* If authenticated, make sure we don't accept this key again */
1.150 djm 724: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 725: fatal_fr(r, "copy key");
1.143 djm 726: if (authctxt->nprev_keys >= INT_MAX ||
727: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
728: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 729: fatal_f("reallocarray failed");
1.143 djm 730: authctxt->prev_keys = tmp;
731: authctxt->prev_keys[authctxt->nprev_keys] = dup;
732: authctxt->nprev_keys++;
733:
734: }
735:
736: /* Checks whether a key has already been previously used for authentication */
737: int
738: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
739: {
740: u_int i;
741: char *fp;
742:
743: for (i = 0; i < authctxt->nprev_keys; i++) {
744: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
745: fp = sshkey_fingerprint(authctxt->prev_keys[i],
746: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 747: debug3_f("key already used: %s %s",
1.143 djm 748: sshkey_type(authctxt->prev_keys[i]),
749: fp == NULL ? "UNKNOWN" : fp);
750: free(fp);
751: return 1;
752: }
753: }
754: return 0;
755: }
756:
757: /*
758: * Updates authctxt->session_info with details of authentication. Should be
759: * whenever an authentication method succeeds.
760: */
761: void
762: auth2_update_session_info(Authctxt *authctxt, const char *method,
763: const char *submethod)
764: {
765: int r;
766:
767: if (authctxt->session_info == NULL) {
768: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 769: fatal_f("sshbuf_new");
1.143 djm 770: }
771:
772: /* Append method[/submethod] */
773: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
774: method, submethod == NULL ? "" : "/",
775: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 776: fatal_fr(r, "append method");
1.143 djm 777:
778: /* Append key if present */
779: if (authctxt->auth_method_key != NULL) {
780: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
781: (r = sshkey_format_text(authctxt->auth_method_key,
782: authctxt->session_info)) != 0)
1.159 djm 783: fatal_fr(r, "append key");
1.143 djm 784: }
785:
786: if (authctxt->auth_method_info != NULL) {
787: /* Ensure no ambiguity here */
788: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 789: fatal_f("auth_method_info contains \\n");
1.143 djm 790: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
791: (r = sshbuf_putf(authctxt->session_info, "%s",
792: authctxt->auth_method_info)) != 0) {
1.159 djm 793: fatal_fr(r, "append method info");
1.143 djm 794: }
795: }
796: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 797: fatal_fr(r, "append");
1.143 djm 798: }
1.117 djm 799:
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