Annotation of src/usr.bin/ssh/auth2.c, Revision 1.164
1.164 ! djm 1: /* $OpenBSD: auth2.c,v 1.163 2021/12/26 23:34:41 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 */
1.163 djm 92: static Authmethod *authmethod_byname(const char *);
1.125 djm 93: static Authmethod *authmethod_lookup(Authctxt *, const char *);
94: static char *authmethods_get(Authctxt *authctxt);
1.127 markus 95:
96: #define MATCH_NONE 0 /* method or submethod mismatch */
97: #define MATCH_METHOD 1 /* method matches (no submethod specified) */
98: #define MATCH_BOTH 2 /* method and submethod match */
99: #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
100: static int list_starts_with(const char *, const char *, const char *);
1.1 markus 101:
1.117 djm 102: char *
103: auth2_read_banner(void)
104: {
105: struct stat st;
106: char *banner = NULL;
107: size_t len, n;
108: int fd;
109:
110: if ((fd = open(options.banner, O_RDONLY)) == -1)
111: return (NULL);
112: if (fstat(fd, &st) == -1) {
113: close(fd);
114: return (NULL);
115: }
1.124 djm 116: if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
1.117 djm 117: close(fd);
118: return (NULL);
119: }
120:
121: len = (size_t)st.st_size; /* truncate */
122: banner = xmalloc(len + 1);
123: n = atomicio(read, fd, banner, len);
124: close(fd);
125:
126: if (n != len) {
1.128 djm 127: free(banner);
1.117 djm 128: return (NULL);
129: }
130: banner[n] = '\0';
131:
132: return (banner);
133: }
134:
135: static void
1.153 djm 136: userauth_banner(struct ssh *ssh)
1.117 djm 137: {
138: char *banner = NULL;
1.153 djm 139: int r;
1.117 djm 140:
1.144 djm 141: if (options.banner == NULL)
1.117 djm 142: return;
143:
144: if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
145: goto done;
146:
1.153 djm 147: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
148: (r = sshpkt_put_cstring(ssh, banner)) != 0 ||
149: (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
150: (r = sshpkt_send(ssh)) != 0)
1.159 djm 151: fatal_fr(r, "send packet");
1.117 djm 152: debug("userauth_banner: sent");
153: done:
1.128 djm 154: free(banner);
1.117 djm 155: }
156:
1.1 markus 157: /*
1.18 markus 158: * loop until authctxt->success == TRUE
1.1 markus 159: */
1.103 markus 160: void
1.153 djm 161: do_authentication2(struct ssh *ssh)
1.1 markus 162: {
1.153 djm 163: Authctxt *authctxt = ssh->authctxt;
164:
1.140 markus 165: ssh_dispatch_init(ssh, &dispatch_protocol_error);
166: ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.142 markus 167: ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
1.138 markus 168: ssh->authctxt = NULL;
1.1 markus 169: }
170:
1.109 deraadt 171: /*ARGSUSED*/
1.135 markus 172: static int
1.139 markus 173: input_service_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 174: {
1.138 markus 175: Authctxt *authctxt = ssh->authctxt;
1.153 djm 176: char *service = NULL;
177: int r, acceptit = 0;
178:
179: if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
180: (r = sshpkt_get_end(ssh)) != 0)
181: goto out;
1.1 markus 182:
1.18 markus 183: if (authctxt == NULL)
184: fatal("input_service_request: no authctxt");
185:
1.1 markus 186: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 187: if (!authctxt->success) {
1.94 deraadt 188: acceptit = 1;
1.1 markus 189: /* now we can handle user-auth requests */
1.153 djm 190: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
191: &input_userauth_request);
1.1 markus 192: }
193: }
194: /* XXX all other service requests are denied */
195:
1.94 deraadt 196: if (acceptit) {
1.153 djm 197: if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
198: (r = sshpkt_put_cstring(ssh, service)) != 0 ||
199: (r = sshpkt_send(ssh)) != 0 ||
200: (r = ssh_packet_write_wait(ssh)) != 0)
201: goto out;
1.1 markus 202: } else {
203: debug("bad service request %s", service);
1.153 djm 204: ssh_packet_disconnect(ssh, "bad service request %s", service);
1.1 markus 205: }
1.153 djm 206: r = 0;
207: out:
1.128 djm 208: free(service);
1.158 markus 209: return r;
1.1 markus 210: }
211:
1.146 dtucker 212: #define MIN_FAIL_DELAY_SECONDS 0.005
213: static double
214: user_specific_delay(const char *user)
215: {
216: char b[512];
217: size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
218: u_char *hash = xmalloc(len);
219: double delay;
220:
1.147 dtucker 221: (void)snprintf(b, sizeof b, "%llu%s",
1.161 djm 222: (unsigned long long)options.timing_secret, user);
1.146 dtucker 223: if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
1.159 djm 224: fatal_f("ssh_digest_memory");
1.146 dtucker 225: /* 0-4.2 ms of delay */
226: delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
227: freezero(hash, len);
1.159 djm 228: debug3_f("user specific delay %0.3lfms", delay/1000);
1.146 dtucker 229: return MIN_FAIL_DELAY_SECONDS + delay;
230: }
231:
232: static void
233: ensure_minimum_time_since(double start, double seconds)
234: {
235: struct timespec ts;
236: double elapsed = monotime_double() - start, req = seconds, remain;
237:
238: /* if we've already passed the requested time, scale up */
239: while ((remain = seconds - elapsed) < 0.0)
240: seconds *= 2;
241:
242: ts.tv_sec = remain;
243: ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
1.159 djm 244: debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
245: elapsed*1000, remain*1000, req*1000);
1.146 dtucker 246: nanosleep(&ts, NULL);
247: }
248:
1.109 deraadt 249: /*ARGSUSED*/
1.135 markus 250: static int
1.139 markus 251: input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 252: {
1.138 markus 253: Authctxt *authctxt = ssh->authctxt;
1.18 markus 254: Authmethod *m = NULL;
1.153 djm 255: char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
256: int r, authenticated = 0;
1.146 dtucker 257: double tstart = monotime_double();
1.1 markus 258:
1.18 markus 259: if (authctxt == NULL)
260: fatal("input_userauth_request: no authctxt");
1.1 markus 261:
1.153 djm 262: if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
263: (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
264: (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
265: goto out;
1.1 markus 266: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 267: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 268:
1.28 markus 269: if ((style = strchr(user, ':')) != NULL)
270: *style++ = 0;
271:
1.164 ! djm 272: if (authctxt->attempt >= 1024)
! 273: auth_maxtries_exceeded(ssh);
1.36 stevesk 274: if (authctxt->attempt++ == 0) {
1.18 markus 275: /* setup auth context */
1.154 djm 276: authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
1.89 markus 277: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 278: authctxt->valid = 1;
1.159 djm 279: debug2_f("setting up authctxt for %s", user);
1.18 markus 280: } else {
1.164 ! djm 281: authctxt->valid = 0;
1.137 djm 282: /* Invalid user, fake password information */
1.102 markus 283: authctxt->pw = fakepw();
1.18 markus 284: }
1.137 djm 285: ssh_packet_set_log_preamble(ssh, "%suser %s",
286: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 287: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 288: use_privsep ? " [net]" : "");
1.18 markus 289: authctxt->user = xstrdup(user);
290: authctxt->service = xstrdup(service);
1.62 markus 291: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 292: if (use_privsep)
293: mm_inform_authserv(service, style);
1.153 djm 294: userauth_banner(ssh);
1.125 djm 295: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 296: ssh_packet_disconnect(ssh,
297: "no authentication methods enabled");
1.62 markus 298: } else if (strcmp(user, authctxt->user) != 0 ||
299: strcmp(service, authctxt->service) != 0) {
1.153 djm 300: ssh_packet_disconnect(ssh, "Change of username or service "
301: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 302: authctxt->user, authctxt->service, user, service);
1.1 markus 303: }
1.28 markus 304: /* reset state */
1.140 markus 305: auth2_challenge_stop(ssh);
1.100 markus 306:
307: #ifdef GSSAPI
1.120 djm 308: /* XXX move to auth2_gssapi_stop() */
1.140 markus 309: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
310: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 311: #endif
312:
1.143 djm 313: auth2_authctxt_reset_info(authctxt);
1.28 markus 314: authctxt->postponed = 0;
1.123 djm 315: authctxt->server_caused_failure = 0;
1.18 markus 316:
1.28 markus 317: /* try to authenticate user */
1.125 djm 318: m = authmethod_lookup(authctxt, method);
1.117 djm 319: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 320: debug2("input_userauth_request: try method %s", method);
1.162 djm 321: authenticated = m->userauth(ssh, method);
1.18 markus 322: }
1.146 dtucker 323: if (!authctxt->authenticated)
324: ensure_minimum_time_since(tstart,
325: user_specific_delay(authctxt->user));
1.140 markus 326: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 327: r = 0;
328: out:
1.128 djm 329: free(service);
330: free(user);
331: free(method);
1.153 djm 332: return r;
1.49 markus 333: }
334:
335: void
1.162 djm 336: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 337: const char *submethod)
1.49 markus 338: {
1.140 markus 339: Authctxt *authctxt = ssh->authctxt;
1.162 djm 340: Authmethod *m = NULL;
341: const char *method = packet_method;
1.60 markus 342: char *methods;
1.153 djm 343: int r, partial = 0;
1.60 markus 344:
1.162 djm 345: if (authenticated) {
346: if (!authctxt->valid) {
347: fatal("INTERNAL ERROR: authenticated invalid user %s",
348: authctxt->user);
349: }
350: if (authctxt->postponed)
351: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 352: /* prefer primary authmethod name to possible synonym */
353: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 354: fatal("INTERNAL ERROR: bad method %s", method);
1.163 djm 355: method = m->name;
1.162 djm 356: }
1.18 markus 357:
358: /* Special handling for root */
1.96 markus 359: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 360: !auth_root_allowed(ssh, method))
1.3 markus 361: authenticated = 0;
362:
1.125 djm 363: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 364: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 365: authenticated = 0;
366: partial = 1;
367: }
368: }
1.126 djm 369:
370: /* Log before sending the reply */
1.154 djm 371: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 372:
1.143 djm 373: /* Update information exposed to session */
374: if (authenticated || partial)
375: auth2_update_session_info(authctxt, method, submethod);
376:
1.126 djm 377: if (authctxt->postponed)
378: return;
1.125 djm 379:
1.60 markus 380: if (authenticated == 1) {
381: /* turn off userauth */
1.153 djm 382: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
383: &dispatch_protocol_ignore);
384: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
385: (r = sshpkt_send(ssh)) != 0 ||
386: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 387: fatal_fr(r, "send success packet");
1.60 markus 388: /* now we can break out */
389: authctxt->success = 1;
1.137 djm 390: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 391: } else {
1.119 djm 392: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 393: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 394: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 395: authctxt->failures++;
396: if (authctxt->failures >= options.max_authtries)
1.154 djm 397: auth_maxtries_exceeded(ssh);
1.125 djm 398: methods = authmethods_get(authctxt);
1.159 djm 399: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 400: partial, methods);
1.153 djm 401: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
402: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
403: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
404: (r = sshpkt_send(ssh)) != 0 ||
405: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 406: fatal_fr(r, "send failure packet");
1.128 djm 407: free(methods);
1.60 markus 408: }
1.1 markus 409: }
1.18 markus 410:
1.125 djm 411: /*
412: * Checks whether method is allowed by at least one AuthenticationMethods
413: * methods list. Returns 1 if allowed, or no methods lists configured.
414: * 0 otherwise.
415: */
1.127 markus 416: int
417: auth2_method_allowed(Authctxt *authctxt, const char *method,
418: const char *submethod)
1.125 djm 419: {
420: u_int i;
421:
422: /*
423: * NB. authctxt->num_auth_methods might be zero as a result of
424: * auth2_setup_methods_lists(), so check the configuration.
425: */
426: if (options.num_auth_methods == 0)
427: return 1;
428: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 429: if (list_starts_with(authctxt->auth_methods[i], method,
430: submethod) != MATCH_NONE)
1.125 djm 431: return 1;
432: }
433: return 0;
434: }
435:
1.67 stevesk 436: static char *
1.125 djm 437: authmethods_get(Authctxt *authctxt)
1.1 markus 438: {
1.148 markus 439: struct sshbuf *b;
1.18 markus 440: char *list;
1.148 markus 441: int i, r;
1.1 markus 442:
1.148 markus 443: if ((b = sshbuf_new()) == NULL)
1.159 djm 444: fatal_f("sshbuf_new failed");
1.93 markus 445: for (i = 0; authmethods[i] != NULL; i++) {
446: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 447: continue;
1.125 djm 448: if (authmethods[i]->enabled == NULL ||
449: *(authmethods[i]->enabled) == 0)
450: continue;
1.127 markus 451: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
452: NULL))
1.125 djm 453: continue;
1.148 markus 454: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
455: authmethods[i]->name)) != 0)
1.159 djm 456: fatal_fr(r, "buffer error");
1.1 markus 457: }
1.148 markus 458: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 459: fatal_f("sshbuf_dup_string failed");
1.148 markus 460: sshbuf_free(b);
1.18 markus 461: return list;
462: }
463:
1.66 itojun 464: static Authmethod *
1.163 djm 465: authmethod_byname(const char *name)
1.18 markus 466: {
1.93 markus 467: int i;
468:
1.163 djm 469: if (name == NULL)
470: fatal_f("NULL authentication method name");
471: for (i = 0; authmethods[i] != NULL; i++) {
472: if (strcmp(name, authmethods[i]->name) == 0 ||
473: (authmethods[i]->synonym != NULL &&
474: strcmp(name, authmethods[i]->synonym) == 0))
475: return authmethods[i];
476: }
477: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 478: return NULL;
1.163 djm 479: }
480:
481: static Authmethod *
482: authmethod_lookup(Authctxt *authctxt, const char *name)
483: {
484: Authmethod *method;
485:
486: if ((method = authmethod_byname(name)) == NULL)
487: return NULL;
488:
489: if (method->enabled == NULL || *(method->enabled) == 0) {
490: debug3_f("method %s not enabled", name);
491: return NULL;
492: }
493: if (!auth2_method_allowed(authctxt, method->name, NULL)) {
494: debug3_f("method %s not allowed "
495: "by AuthenticationMethods", name);
496: return NULL;
497: }
498: return method;
1.1 markus 499: }
1.125 djm 500:
501: /*
502: * Check a comma-separated list of methods for validity. Is need_enable is
503: * non-zero, then also require that the methods are enabled.
504: * Returns 0 on success or -1 if the methods list is invalid.
505: */
506: int
507: auth2_methods_valid(const char *_methods, int need_enable)
508: {
1.127 markus 509: char *methods, *omethods, *method, *p;
1.125 djm 510: u_int i, found;
511: int ret = -1;
512:
513: if (*_methods == '\0') {
514: error("empty authentication method list");
515: return -1;
516: }
517: omethods = methods = xstrdup(_methods);
518: while ((method = strsep(&methods, ",")) != NULL) {
519: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 520: if ((p = strchr(method, ':')) != NULL)
521: *p = '\0';
1.125 djm 522: if (strcmp(method, authmethods[i]->name) != 0)
523: continue;
524: if (need_enable) {
525: if (authmethods[i]->enabled == NULL ||
526: *(authmethods[i]->enabled) == 0) {
527: error("Disabled method \"%s\" in "
528: "AuthenticationMethods list \"%s\"",
529: method, _methods);
530: goto out;
531: }
532: }
533: found = 1;
534: break;
535: }
536: if (!found) {
537: error("Unknown authentication method \"%s\" in list",
538: method);
539: goto out;
540: }
541: }
542: ret = 0;
543: out:
544: free(omethods);
545: return ret;
546: }
547:
548: /*
549: * Prune the AuthenticationMethods supplied in the configuration, removing
550: * any methods lists that include disabled methods. Note that this might
551: * leave authctxt->num_auth_methods == 0, even when multiple required auth
552: * has been requested. For this reason, all tests for whether multiple is
553: * enabled should consult options.num_auth_methods directly.
554: */
555: int
556: auth2_setup_methods_lists(Authctxt *authctxt)
557: {
558: u_int i;
1.155 djm 559:
560: /* First, normalise away the "any" pseudo-method */
561: if (options.num_auth_methods == 1 &&
562: strcmp(options.auth_methods[0], "any") == 0) {
563: free(options.auth_methods[0]);
564: options.auth_methods[0] = NULL;
565: options.num_auth_methods = 0;
566: }
1.125 djm 567:
568: if (options.num_auth_methods == 0)
569: return 0;
1.159 djm 570: debug3_f("checking methods");
1.125 djm 571: authctxt->auth_methods = xcalloc(options.num_auth_methods,
572: sizeof(*authctxt->auth_methods));
573: authctxt->num_auth_methods = 0;
574: for (i = 0; i < options.num_auth_methods; i++) {
575: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
576: logit("Authentication methods list \"%s\" contains "
577: "disabled method, skipping",
578: options.auth_methods[i]);
579: continue;
580: }
581: debug("authentication methods list %d: %s",
582: authctxt->num_auth_methods, options.auth_methods[i]);
583: authctxt->auth_methods[authctxt->num_auth_methods++] =
584: xstrdup(options.auth_methods[i]);
585: }
586: if (authctxt->num_auth_methods == 0) {
587: error("No AuthenticationMethods left after eliminating "
588: "disabled methods");
589: return -1;
590: }
591: return 0;
592: }
593:
594: static int
1.127 markus 595: list_starts_with(const char *methods, const char *method,
596: const char *submethod)
1.125 djm 597: {
598: size_t l = strlen(method);
1.127 markus 599: int match;
600: const char *p;
1.125 djm 601:
602: if (strncmp(methods, method, l) != 0)
1.127 markus 603: return MATCH_NONE;
604: p = methods + l;
605: match = MATCH_METHOD;
606: if (*p == ':') {
607: if (!submethod)
608: return MATCH_PARTIAL;
609: l = strlen(submethod);
610: p += 1;
611: if (strncmp(submethod, p, l))
612: return MATCH_NONE;
613: p += l;
614: match = MATCH_BOTH;
615: }
616: if (*p != ',' && *p != '\0')
617: return MATCH_NONE;
618: return match;
1.125 djm 619: }
620:
621: /*
622: * Remove method from the start of a comma-separated list of methods.
623: * Returns 0 if the list of methods did not start with that method or 1
624: * if it did.
625: */
626: static int
1.127 markus 627: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 628: {
1.127 markus 629: char *omethods = *methods, *p;
1.125 djm 630: size_t l = strlen(method);
1.127 markus 631: int match;
1.125 djm 632:
1.127 markus 633: match = list_starts_with(omethods, method, submethod);
634: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 635: return 0;
1.127 markus 636: p = omethods + l;
637: if (submethod && match == MATCH_BOTH)
638: p += 1 + strlen(submethod); /* include colon */
639: if (*p == ',')
640: p++;
641: *methods = xstrdup(p);
1.125 djm 642: free(omethods);
643: return 1;
644: }
645:
646: /*
647: * Called after successful authentication. Will remove the successful method
648: * from the start of each list in which it occurs. If it was the last method
649: * in any list, then authentication is deemed successful.
650: * Returns 1 if the method completed any authentication list or 0 otherwise.
651: */
652: int
1.127 markus 653: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
654: const char *submethod)
1.125 djm 655: {
656: u_int i, found = 0;
657:
1.159 djm 658: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 659: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 660: if (!remove_method(&(authctxt->auth_methods[i]), method,
661: submethod))
1.125 djm 662: continue;
663: found = 1;
664: if (*authctxt->auth_methods[i] == '\0') {
665: debug2("authentication methods list %d complete", i);
666: return 1;
667: }
668: debug3("authentication methods list %d remaining: \"%s\"",
669: i, authctxt->auth_methods[i]);
670: }
671: /* This should not happen, but would be bad if it did */
672: if (!found)
1.159 djm 673: fatal_f("method not in AuthenticationMethods");
1.125 djm 674: return 0;
675: }
676:
1.143 djm 677: /* Reset method-specific information */
678: void auth2_authctxt_reset_info(Authctxt *authctxt)
679: {
680: sshkey_free(authctxt->auth_method_key);
681: free(authctxt->auth_method_info);
682: authctxt->auth_method_key = NULL;
683: authctxt->auth_method_info = NULL;
684: }
685:
686: /* Record auth method-specific information for logs */
687: void
688: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
689: {
690: va_list ap;
1.161 djm 691: int i;
1.143 djm 692:
693: free(authctxt->auth_method_info);
694: authctxt->auth_method_info = NULL;
695:
696: va_start(ap, fmt);
697: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
698: va_end(ap);
699:
1.156 deraadt 700: if (i == -1)
1.159 djm 701: fatal_f("vasprintf failed");
1.143 djm 702: }
703:
704: /*
705: * Records a public key used in authentication. This is used for logging
706: * and to ensure that the same key is not subsequently accepted again for
707: * multiple authentication.
708: */
709: void
710: auth2_record_key(Authctxt *authctxt, int authenticated,
711: const struct sshkey *key)
712: {
713: struct sshkey **tmp, *dup;
714: int r;
715:
1.150 djm 716: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 717: fatal_fr(r, "copy key");
1.143 djm 718: sshkey_free(authctxt->auth_method_key);
719: authctxt->auth_method_key = dup;
720:
721: if (!authenticated)
722: return;
723:
724: /* If authenticated, make sure we don't accept this key again */
1.150 djm 725: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 726: fatal_fr(r, "copy key");
1.143 djm 727: if (authctxt->nprev_keys >= INT_MAX ||
728: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
729: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 730: fatal_f("reallocarray failed");
1.143 djm 731: authctxt->prev_keys = tmp;
732: authctxt->prev_keys[authctxt->nprev_keys] = dup;
733: authctxt->nprev_keys++;
734:
735: }
736:
737: /* Checks whether a key has already been previously used for authentication */
738: int
739: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
740: {
741: u_int i;
742: char *fp;
743:
744: for (i = 0; i < authctxt->nprev_keys; i++) {
745: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
746: fp = sshkey_fingerprint(authctxt->prev_keys[i],
747: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 748: debug3_f("key already used: %s %s",
1.143 djm 749: sshkey_type(authctxt->prev_keys[i]),
750: fp == NULL ? "UNKNOWN" : fp);
751: free(fp);
752: return 1;
753: }
754: }
755: return 0;
756: }
757:
758: /*
759: * Updates authctxt->session_info with details of authentication. Should be
760: * whenever an authentication method succeeds.
761: */
762: void
763: auth2_update_session_info(Authctxt *authctxt, const char *method,
764: const char *submethod)
765: {
766: int r;
767:
768: if (authctxt->session_info == NULL) {
769: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 770: fatal_f("sshbuf_new");
1.143 djm 771: }
772:
773: /* Append method[/submethod] */
774: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
775: method, submethod == NULL ? "" : "/",
776: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 777: fatal_fr(r, "append method");
1.143 djm 778:
779: /* Append key if present */
780: if (authctxt->auth_method_key != NULL) {
781: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
782: (r = sshkey_format_text(authctxt->auth_method_key,
783: authctxt->session_info)) != 0)
1.159 djm 784: fatal_fr(r, "append key");
1.143 djm 785: }
786:
787: if (authctxt->auth_method_info != NULL) {
788: /* Ensure no ambiguity here */
789: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 790: fatal_f("auth_method_info contains \\n");
1.143 djm 791: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
792: (r = sshbuf_putf(authctxt->session_info, "%s",
793: authctxt->auth_method_info)) != 0) {
1.159 djm 794: fatal_fr(r, "append method info");
1.143 djm 795: }
796: }
797: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 798: fatal_fr(r, "append");
1.143 djm 799: }
1.117 djm 800:
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