Annotation of src/usr.bin/ssh/auth2.c, Revision 1.168
1.168 ! djm 1: /* $OpenBSD: auth2.c,v 1.167 2023/08/28 09:48:11 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"
1.168 ! djm 58: #include "kex.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);
1.168 ! djm 166: if (ssh->kex->ext_info_c)
! 167: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
1.140 markus 168: ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.142 markus 169: ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
1.138 markus 170: ssh->authctxt = NULL;
1.1 markus 171: }
172:
1.135 markus 173: static int
1.139 markus 174: input_service_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 175: {
1.138 markus 176: Authctxt *authctxt = ssh->authctxt;
1.153 djm 177: char *service = NULL;
178: int r, acceptit = 0;
179:
180: if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
181: (r = sshpkt_get_end(ssh)) != 0)
182: goto out;
1.1 markus 183:
1.18 markus 184: if (authctxt == NULL)
185: fatal("input_service_request: no authctxt");
186:
1.1 markus 187: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 188: if (!authctxt->success) {
1.94 deraadt 189: acceptit = 1;
1.1 markus 190: /* now we can handle user-auth requests */
1.153 djm 191: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
192: &input_userauth_request);
1.1 markus 193: }
194: }
195: /* XXX all other service requests are denied */
196:
1.94 deraadt 197: if (acceptit) {
1.153 djm 198: if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
199: (r = sshpkt_put_cstring(ssh, service)) != 0 ||
200: (r = sshpkt_send(ssh)) != 0 ||
201: (r = ssh_packet_write_wait(ssh)) != 0)
202: goto out;
1.1 markus 203: } else {
204: debug("bad service request %s", service);
1.153 djm 205: ssh_packet_disconnect(ssh, "bad service request %s", service);
1.1 markus 206: }
1.168 ! djm 207: ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error);
1.153 djm 208: r = 0;
209: out:
1.128 djm 210: free(service);
1.158 markus 211: return r;
1.1 markus 212: }
213:
1.146 dtucker 214: #define MIN_FAIL_DELAY_SECONDS 0.005
1.167 djm 215: #define MAX_FAIL_DELAY_SECONDS 5.0
1.146 dtucker 216: static double
217: user_specific_delay(const char *user)
218: {
219: char b[512];
220: size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
221: u_char *hash = xmalloc(len);
222: double delay;
223:
1.147 dtucker 224: (void)snprintf(b, sizeof b, "%llu%s",
1.161 djm 225: (unsigned long long)options.timing_secret, user);
1.146 dtucker 226: if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
1.159 djm 227: fatal_f("ssh_digest_memory");
1.146 dtucker 228: /* 0-4.2 ms of delay */
229: delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
230: freezero(hash, len);
1.159 djm 231: debug3_f("user specific delay %0.3lfms", delay/1000);
1.146 dtucker 232: return MIN_FAIL_DELAY_SECONDS + delay;
233: }
234:
235: static void
236: ensure_minimum_time_since(double start, double seconds)
237: {
238: struct timespec ts;
239: double elapsed = monotime_double() - start, req = seconds, remain;
240:
1.167 djm 241: if (elapsed > MAX_FAIL_DELAY_SECONDS) {
242: debug3_f("elapsed %0.3lfms exceeded the max delay "
243: "requested %0.3lfms)", elapsed*1000, req*1000);
244: return;
245: }
246:
1.146 dtucker 247: /* if we've already passed the requested time, scale up */
248: while ((remain = seconds - elapsed) < 0.0)
249: seconds *= 2;
250:
251: ts.tv_sec = remain;
252: ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
1.159 djm 253: debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
254: elapsed*1000, remain*1000, req*1000);
1.146 dtucker 255: nanosleep(&ts, NULL);
256: }
257:
1.135 markus 258: static int
1.139 markus 259: input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 260: {
1.138 markus 261: Authctxt *authctxt = ssh->authctxt;
1.18 markus 262: Authmethod *m = NULL;
1.153 djm 263: char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
264: int r, authenticated = 0;
1.146 dtucker 265: double tstart = monotime_double();
1.1 markus 266:
1.18 markus 267: if (authctxt == NULL)
268: fatal("input_userauth_request: no authctxt");
1.1 markus 269:
1.153 djm 270: if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
271: (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
272: (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
273: goto out;
1.1 markus 274: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 275: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 276:
1.28 markus 277: if ((style = strchr(user, ':')) != NULL)
278: *style++ = 0;
279:
1.164 djm 280: if (authctxt->attempt >= 1024)
281: auth_maxtries_exceeded(ssh);
1.36 stevesk 282: if (authctxt->attempt++ == 0) {
1.18 markus 283: /* setup auth context */
1.154 djm 284: authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
1.89 markus 285: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 286: authctxt->valid = 1;
1.159 djm 287: debug2_f("setting up authctxt for %s", user);
1.18 markus 288: } else {
1.164 djm 289: authctxt->valid = 0;
1.137 djm 290: /* Invalid user, fake password information */
1.102 markus 291: authctxt->pw = fakepw();
1.18 markus 292: }
1.137 djm 293: ssh_packet_set_log_preamble(ssh, "%suser %s",
294: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 295: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 296: use_privsep ? " [net]" : "");
1.18 markus 297: authctxt->user = xstrdup(user);
298: authctxt->service = xstrdup(service);
1.62 markus 299: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 300: if (use_privsep)
301: mm_inform_authserv(service, style);
1.153 djm 302: userauth_banner(ssh);
1.168 ! djm 303: if ((r = kex_server_update_ext_info(ssh)) != 0)
! 304: fatal_fr(r, "kex_server_update_ext_info failed");
1.125 djm 305: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 306: ssh_packet_disconnect(ssh,
307: "no authentication methods enabled");
1.62 markus 308: } else if (strcmp(user, authctxt->user) != 0 ||
309: strcmp(service, authctxt->service) != 0) {
1.153 djm 310: ssh_packet_disconnect(ssh, "Change of username or service "
311: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 312: authctxt->user, authctxt->service, user, service);
1.1 markus 313: }
1.28 markus 314: /* reset state */
1.140 markus 315: auth2_challenge_stop(ssh);
1.100 markus 316:
317: #ifdef GSSAPI
1.120 djm 318: /* XXX move to auth2_gssapi_stop() */
1.140 markus 319: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
320: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 321: #endif
322:
1.143 djm 323: auth2_authctxt_reset_info(authctxt);
1.28 markus 324: authctxt->postponed = 0;
1.123 djm 325: authctxt->server_caused_failure = 0;
1.18 markus 326:
1.28 markus 327: /* try to authenticate user */
1.125 djm 328: m = authmethod_lookup(authctxt, method);
1.117 djm 329: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 330: debug2("input_userauth_request: try method %s", method);
1.162 djm 331: authenticated = m->userauth(ssh, method);
1.18 markus 332: }
1.167 djm 333: if (!authctxt->authenticated && strcmp(method, "none") != 0)
1.146 dtucker 334: ensure_minimum_time_since(tstart,
335: user_specific_delay(authctxt->user));
1.140 markus 336: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 337: r = 0;
338: out:
1.128 djm 339: free(service);
340: free(user);
341: free(method);
1.153 djm 342: return r;
1.49 markus 343: }
344:
345: void
1.162 djm 346: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 347: const char *submethod)
1.49 markus 348: {
1.140 markus 349: Authctxt *authctxt = ssh->authctxt;
1.162 djm 350: Authmethod *m = NULL;
351: const char *method = packet_method;
1.60 markus 352: char *methods;
1.153 djm 353: int r, partial = 0;
1.60 markus 354:
1.162 djm 355: if (authenticated) {
356: if (!authctxt->valid) {
357: fatal("INTERNAL ERROR: authenticated invalid user %s",
358: authctxt->user);
359: }
360: if (authctxt->postponed)
361: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 362: /* prefer primary authmethod name to possible synonym */
363: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 364: fatal("INTERNAL ERROR: bad method %s", method);
1.163 djm 365: method = m->name;
1.162 djm 366: }
1.18 markus 367:
368: /* Special handling for root */
1.96 markus 369: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 370: !auth_root_allowed(ssh, method))
1.3 markus 371: authenticated = 0;
372:
1.125 djm 373: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 374: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 375: authenticated = 0;
376: partial = 1;
377: }
378: }
1.126 djm 379:
380: /* Log before sending the reply */
1.154 djm 381: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 382:
1.143 djm 383: /* Update information exposed to session */
384: if (authenticated || partial)
385: auth2_update_session_info(authctxt, method, submethod);
386:
1.126 djm 387: if (authctxt->postponed)
388: return;
1.125 djm 389:
1.60 markus 390: if (authenticated == 1) {
391: /* turn off userauth */
1.153 djm 392: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
393: &dispatch_protocol_ignore);
394: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
395: (r = sshpkt_send(ssh)) != 0 ||
396: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 397: fatal_fr(r, "send success packet");
1.60 markus 398: /* now we can break out */
399: authctxt->success = 1;
1.137 djm 400: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 401: } else {
1.119 djm 402: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 403: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 404: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 405: authctxt->failures++;
406: if (authctxt->failures >= options.max_authtries)
1.154 djm 407: auth_maxtries_exceeded(ssh);
1.125 djm 408: methods = authmethods_get(authctxt);
1.159 djm 409: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 410: partial, methods);
1.153 djm 411: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
412: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
413: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
414: (r = sshpkt_send(ssh)) != 0 ||
415: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 416: fatal_fr(r, "send failure packet");
1.128 djm 417: free(methods);
1.60 markus 418: }
1.1 markus 419: }
1.18 markus 420:
1.125 djm 421: /*
422: * Checks whether method is allowed by at least one AuthenticationMethods
423: * methods list. Returns 1 if allowed, or no methods lists configured.
424: * 0 otherwise.
425: */
1.127 markus 426: int
427: auth2_method_allowed(Authctxt *authctxt, const char *method,
428: const char *submethod)
1.125 djm 429: {
430: u_int i;
431:
432: /*
433: * NB. authctxt->num_auth_methods might be zero as a result of
434: * auth2_setup_methods_lists(), so check the configuration.
435: */
436: if (options.num_auth_methods == 0)
437: return 1;
438: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 439: if (list_starts_with(authctxt->auth_methods[i], method,
440: submethod) != MATCH_NONE)
1.125 djm 441: return 1;
442: }
443: return 0;
444: }
445:
1.67 stevesk 446: static char *
1.125 djm 447: authmethods_get(Authctxt *authctxt)
1.1 markus 448: {
1.148 markus 449: struct sshbuf *b;
1.18 markus 450: char *list;
1.148 markus 451: int i, r;
1.1 markus 452:
1.148 markus 453: if ((b = sshbuf_new()) == NULL)
1.159 djm 454: fatal_f("sshbuf_new failed");
1.93 markus 455: for (i = 0; authmethods[i] != NULL; i++) {
456: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 457: continue;
1.125 djm 458: if (authmethods[i]->enabled == NULL ||
459: *(authmethods[i]->enabled) == 0)
460: continue;
1.127 markus 461: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
462: NULL))
1.125 djm 463: continue;
1.148 markus 464: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
465: authmethods[i]->name)) != 0)
1.159 djm 466: fatal_fr(r, "buffer error");
1.1 markus 467: }
1.148 markus 468: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 469: fatal_f("sshbuf_dup_string failed");
1.148 markus 470: sshbuf_free(b);
1.18 markus 471: return list;
472: }
473:
1.66 itojun 474: static Authmethod *
1.163 djm 475: authmethod_byname(const char *name)
1.18 markus 476: {
1.93 markus 477: int i;
478:
1.163 djm 479: if (name == NULL)
480: fatal_f("NULL authentication method name");
481: for (i = 0; authmethods[i] != NULL; i++) {
482: if (strcmp(name, authmethods[i]->name) == 0 ||
483: (authmethods[i]->synonym != NULL &&
484: strcmp(name, authmethods[i]->synonym) == 0))
485: return authmethods[i];
486: }
487: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 488: return NULL;
1.163 djm 489: }
490:
491: static Authmethod *
492: authmethod_lookup(Authctxt *authctxt, const char *name)
493: {
494: Authmethod *method;
495:
496: if ((method = authmethod_byname(name)) == NULL)
497: return NULL;
498:
499: if (method->enabled == NULL || *(method->enabled) == 0) {
500: debug3_f("method %s not enabled", name);
501: return NULL;
502: }
503: if (!auth2_method_allowed(authctxt, method->name, NULL)) {
504: debug3_f("method %s not allowed "
505: "by AuthenticationMethods", name);
506: return NULL;
507: }
508: return method;
1.1 markus 509: }
1.125 djm 510:
511: /*
512: * Check a comma-separated list of methods for validity. Is need_enable is
513: * non-zero, then also require that the methods are enabled.
514: * Returns 0 on success or -1 if the methods list is invalid.
515: */
516: int
517: auth2_methods_valid(const char *_methods, int need_enable)
518: {
1.127 markus 519: char *methods, *omethods, *method, *p;
1.125 djm 520: u_int i, found;
521: int ret = -1;
522:
523: if (*_methods == '\0') {
524: error("empty authentication method list");
525: return -1;
526: }
527: omethods = methods = xstrdup(_methods);
528: while ((method = strsep(&methods, ",")) != NULL) {
529: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 530: if ((p = strchr(method, ':')) != NULL)
531: *p = '\0';
1.125 djm 532: if (strcmp(method, authmethods[i]->name) != 0)
533: continue;
534: if (need_enable) {
535: if (authmethods[i]->enabled == NULL ||
536: *(authmethods[i]->enabled) == 0) {
537: error("Disabled method \"%s\" in "
538: "AuthenticationMethods list \"%s\"",
539: method, _methods);
540: goto out;
541: }
542: }
543: found = 1;
544: break;
545: }
546: if (!found) {
547: error("Unknown authentication method \"%s\" in list",
548: method);
549: goto out;
550: }
551: }
552: ret = 0;
553: out:
554: free(omethods);
555: return ret;
556: }
557:
558: /*
559: * Prune the AuthenticationMethods supplied in the configuration, removing
560: * any methods lists that include disabled methods. Note that this might
561: * leave authctxt->num_auth_methods == 0, even when multiple required auth
562: * has been requested. For this reason, all tests for whether multiple is
563: * enabled should consult options.num_auth_methods directly.
564: */
565: int
566: auth2_setup_methods_lists(Authctxt *authctxt)
567: {
568: u_int i;
1.155 djm 569:
570: /* First, normalise away the "any" pseudo-method */
571: if (options.num_auth_methods == 1 &&
572: strcmp(options.auth_methods[0], "any") == 0) {
573: free(options.auth_methods[0]);
574: options.auth_methods[0] = NULL;
575: options.num_auth_methods = 0;
576: }
1.125 djm 577:
578: if (options.num_auth_methods == 0)
579: return 0;
1.159 djm 580: debug3_f("checking methods");
1.125 djm 581: authctxt->auth_methods = xcalloc(options.num_auth_methods,
582: sizeof(*authctxt->auth_methods));
583: authctxt->num_auth_methods = 0;
584: for (i = 0; i < options.num_auth_methods; i++) {
585: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
586: logit("Authentication methods list \"%s\" contains "
587: "disabled method, skipping",
588: options.auth_methods[i]);
589: continue;
590: }
591: debug("authentication methods list %d: %s",
592: authctxt->num_auth_methods, options.auth_methods[i]);
593: authctxt->auth_methods[authctxt->num_auth_methods++] =
594: xstrdup(options.auth_methods[i]);
595: }
596: if (authctxt->num_auth_methods == 0) {
597: error("No AuthenticationMethods left after eliminating "
598: "disabled methods");
599: return -1;
600: }
601: return 0;
602: }
603:
604: static int
1.127 markus 605: list_starts_with(const char *methods, const char *method,
606: const char *submethod)
1.125 djm 607: {
608: size_t l = strlen(method);
1.127 markus 609: int match;
610: const char *p;
1.125 djm 611:
612: if (strncmp(methods, method, l) != 0)
1.127 markus 613: return MATCH_NONE;
614: p = methods + l;
615: match = MATCH_METHOD;
616: if (*p == ':') {
617: if (!submethod)
618: return MATCH_PARTIAL;
619: l = strlen(submethod);
620: p += 1;
621: if (strncmp(submethod, p, l))
622: return MATCH_NONE;
623: p += l;
624: match = MATCH_BOTH;
625: }
626: if (*p != ',' && *p != '\0')
627: return MATCH_NONE;
628: return match;
1.125 djm 629: }
630:
631: /*
632: * Remove method from the start of a comma-separated list of methods.
633: * Returns 0 if the list of methods did not start with that method or 1
634: * if it did.
635: */
636: static int
1.127 markus 637: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 638: {
1.127 markus 639: char *omethods = *methods, *p;
1.125 djm 640: size_t l = strlen(method);
1.127 markus 641: int match;
1.125 djm 642:
1.127 markus 643: match = list_starts_with(omethods, method, submethod);
644: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 645: return 0;
1.127 markus 646: p = omethods + l;
647: if (submethod && match == MATCH_BOTH)
648: p += 1 + strlen(submethod); /* include colon */
649: if (*p == ',')
650: p++;
651: *methods = xstrdup(p);
1.125 djm 652: free(omethods);
653: return 1;
654: }
655:
656: /*
657: * Called after successful authentication. Will remove the successful method
658: * from the start of each list in which it occurs. If it was the last method
659: * in any list, then authentication is deemed successful.
660: * Returns 1 if the method completed any authentication list or 0 otherwise.
661: */
662: int
1.127 markus 663: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
664: const char *submethod)
1.125 djm 665: {
666: u_int i, found = 0;
667:
1.159 djm 668: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 669: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 670: if (!remove_method(&(authctxt->auth_methods[i]), method,
671: submethod))
1.125 djm 672: continue;
673: found = 1;
674: if (*authctxt->auth_methods[i] == '\0') {
675: debug2("authentication methods list %d complete", i);
676: return 1;
677: }
678: debug3("authentication methods list %d remaining: \"%s\"",
679: i, authctxt->auth_methods[i]);
680: }
681: /* This should not happen, but would be bad if it did */
682: if (!found)
1.159 djm 683: fatal_f("method not in AuthenticationMethods");
1.125 djm 684: return 0;
685: }
686:
1.143 djm 687: /* Reset method-specific information */
688: void auth2_authctxt_reset_info(Authctxt *authctxt)
689: {
690: sshkey_free(authctxt->auth_method_key);
691: free(authctxt->auth_method_info);
692: authctxt->auth_method_key = NULL;
693: authctxt->auth_method_info = NULL;
694: }
695:
696: /* Record auth method-specific information for logs */
697: void
698: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
699: {
700: va_list ap;
1.161 djm 701: int i;
1.143 djm 702:
703: free(authctxt->auth_method_info);
704: authctxt->auth_method_info = NULL;
705:
706: va_start(ap, fmt);
707: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
708: va_end(ap);
709:
1.156 deraadt 710: if (i == -1)
1.159 djm 711: fatal_f("vasprintf failed");
1.143 djm 712: }
713:
714: /*
715: * Records a public key used in authentication. This is used for logging
716: * and to ensure that the same key is not subsequently accepted again for
717: * multiple authentication.
718: */
719: void
720: auth2_record_key(Authctxt *authctxt, int authenticated,
721: const struct sshkey *key)
722: {
723: struct sshkey **tmp, *dup;
724: int r;
725:
1.150 djm 726: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 727: fatal_fr(r, "copy key");
1.143 djm 728: sshkey_free(authctxt->auth_method_key);
729: authctxt->auth_method_key = dup;
730:
731: if (!authenticated)
732: return;
733:
734: /* If authenticated, make sure we don't accept this key again */
1.150 djm 735: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 736: fatal_fr(r, "copy key");
1.143 djm 737: if (authctxt->nprev_keys >= INT_MAX ||
738: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
739: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 740: fatal_f("reallocarray failed");
1.143 djm 741: authctxt->prev_keys = tmp;
742: authctxt->prev_keys[authctxt->nprev_keys] = dup;
743: authctxt->nprev_keys++;
744:
745: }
746:
747: /* Checks whether a key has already been previously used for authentication */
748: int
749: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
750: {
751: u_int i;
752: char *fp;
753:
754: for (i = 0; i < authctxt->nprev_keys; i++) {
755: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
756: fp = sshkey_fingerprint(authctxt->prev_keys[i],
757: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 758: debug3_f("key already used: %s %s",
1.143 djm 759: sshkey_type(authctxt->prev_keys[i]),
760: fp == NULL ? "UNKNOWN" : fp);
761: free(fp);
762: return 1;
763: }
764: }
765: return 0;
766: }
767:
768: /*
769: * Updates authctxt->session_info with details of authentication. Should be
770: * whenever an authentication method succeeds.
771: */
772: void
773: auth2_update_session_info(Authctxt *authctxt, const char *method,
774: const char *submethod)
775: {
776: int r;
777:
778: if (authctxt->session_info == NULL) {
779: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 780: fatal_f("sshbuf_new");
1.143 djm 781: }
782:
783: /* Append method[/submethod] */
784: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
785: method, submethod == NULL ? "" : "/",
786: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 787: fatal_fr(r, "append method");
1.143 djm 788:
789: /* Append key if present */
790: if (authctxt->auth_method_key != NULL) {
791: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
792: (r = sshkey_format_text(authctxt->auth_method_key,
793: authctxt->session_info)) != 0)
1.159 djm 794: fatal_fr(r, "append key");
1.143 djm 795: }
796:
797: if (authctxt->auth_method_info != NULL) {
798: /* Ensure no ambiguity here */
799: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 800: fatal_f("auth_method_info contains \\n");
1.143 djm 801: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
802: (r = sshbuf_putf(authctxt->session_info, "%s",
803: authctxt->auth_method_info)) != 0) {
1.159 djm 804: fatal_fr(r, "append method info");
1.143 djm 805: }
806: }
807: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 808: fatal_fr(r, "append");
1.143 djm 809: }
1.117 djm 810:
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