Annotation of src/usr.bin/ssh/auth2.c, Revision 1.169
1.169 ! djm 1: /* $OpenBSD: auth2.c,v 1.168 2023/12/18 14:45:49 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:
1.169 ! djm 144: if ((banner = mm_auth2_read_banner()) == NULL)
1.117 djm 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 */
1.169 ! djm 284: authctxt->pw = mm_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);
1.169 ! djm 295: setproctitle("%s [net]", authctxt->valid ? user : "unknown");
1.18 markus 296: authctxt->user = xstrdup(user);
297: authctxt->service = xstrdup(service);
1.62 markus 298: authctxt->style = style ? xstrdup(style) : NULL;
1.169 ! djm 299: mm_inform_authserv(service, style);
1.153 djm 300: userauth_banner(ssh);
1.168 djm 301: if ((r = kex_server_update_ext_info(ssh)) != 0)
302: fatal_fr(r, "kex_server_update_ext_info failed");
1.125 djm 303: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 304: ssh_packet_disconnect(ssh,
305: "no authentication methods enabled");
1.62 markus 306: } else if (strcmp(user, authctxt->user) != 0 ||
307: strcmp(service, authctxt->service) != 0) {
1.153 djm 308: ssh_packet_disconnect(ssh, "Change of username or service "
309: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 310: authctxt->user, authctxt->service, user, service);
1.1 markus 311: }
1.28 markus 312: /* reset state */
1.140 markus 313: auth2_challenge_stop(ssh);
1.100 markus 314:
315: #ifdef GSSAPI
1.120 djm 316: /* XXX move to auth2_gssapi_stop() */
1.140 markus 317: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
318: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 319: #endif
320:
1.143 djm 321: auth2_authctxt_reset_info(authctxt);
1.28 markus 322: authctxt->postponed = 0;
1.123 djm 323: authctxt->server_caused_failure = 0;
1.18 markus 324:
1.28 markus 325: /* try to authenticate user */
1.125 djm 326: m = authmethod_lookup(authctxt, method);
1.117 djm 327: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 328: debug2("input_userauth_request: try method %s", method);
1.162 djm 329: authenticated = m->userauth(ssh, method);
1.18 markus 330: }
1.167 djm 331: if (!authctxt->authenticated && strcmp(method, "none") != 0)
1.146 dtucker 332: ensure_minimum_time_since(tstart,
333: user_specific_delay(authctxt->user));
1.140 markus 334: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 335: r = 0;
336: out:
1.128 djm 337: free(service);
338: free(user);
339: free(method);
1.153 djm 340: return r;
1.49 markus 341: }
342:
343: void
1.162 djm 344: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 345: const char *submethod)
1.49 markus 346: {
1.140 markus 347: Authctxt *authctxt = ssh->authctxt;
1.162 djm 348: Authmethod *m = NULL;
349: const char *method = packet_method;
1.60 markus 350: char *methods;
1.153 djm 351: int r, partial = 0;
1.60 markus 352:
1.162 djm 353: if (authenticated) {
354: if (!authctxt->valid) {
355: fatal("INTERNAL ERROR: authenticated invalid user %s",
356: authctxt->user);
357: }
358: if (authctxt->postponed)
359: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 360: /* prefer primary authmethod name to possible synonym */
361: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 362: fatal("INTERNAL ERROR: bad method %s", method);
1.169 ! djm 363: method = m->cfg->name;
1.162 djm 364: }
1.18 markus 365:
366: /* Special handling for root */
1.96 markus 367: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 368: !auth_root_allowed(ssh, method))
1.3 markus 369: authenticated = 0;
370:
1.125 djm 371: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 372: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 373: authenticated = 0;
374: partial = 1;
375: }
376: }
1.126 djm 377:
378: /* Log before sending the reply */
1.154 djm 379: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 380:
1.143 djm 381: /* Update information exposed to session */
382: if (authenticated || partial)
383: auth2_update_session_info(authctxt, method, submethod);
384:
1.126 djm 385: if (authctxt->postponed)
386: return;
1.125 djm 387:
1.60 markus 388: if (authenticated == 1) {
389: /* turn off userauth */
1.153 djm 390: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
391: &dispatch_protocol_ignore);
392: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
393: (r = sshpkt_send(ssh)) != 0 ||
394: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 395: fatal_fr(r, "send success packet");
1.60 markus 396: /* now we can break out */
397: authctxt->success = 1;
1.137 djm 398: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 399: } else {
1.119 djm 400: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 401: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 402: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 403: authctxt->failures++;
404: if (authctxt->failures >= options.max_authtries)
1.154 djm 405: auth_maxtries_exceeded(ssh);
1.125 djm 406: methods = authmethods_get(authctxt);
1.159 djm 407: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 408: partial, methods);
1.153 djm 409: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
410: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
411: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
412: (r = sshpkt_send(ssh)) != 0 ||
413: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 414: fatal_fr(r, "send failure packet");
1.128 djm 415: free(methods);
1.60 markus 416: }
1.1 markus 417: }
1.18 markus 418:
1.125 djm 419: /*
420: * Checks whether method is allowed by at least one AuthenticationMethods
421: * methods list. Returns 1 if allowed, or no methods lists configured.
422: * 0 otherwise.
423: */
1.127 markus 424: int
425: auth2_method_allowed(Authctxt *authctxt, const char *method,
426: const char *submethod)
1.125 djm 427: {
428: u_int i;
429:
430: /*
431: * NB. authctxt->num_auth_methods might be zero as a result of
432: * auth2_setup_methods_lists(), so check the configuration.
433: */
434: if (options.num_auth_methods == 0)
435: return 1;
436: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 437: if (list_starts_with(authctxt->auth_methods[i], method,
438: submethod) != MATCH_NONE)
1.125 djm 439: return 1;
440: }
441: return 0;
442: }
443:
1.67 stevesk 444: static char *
1.125 djm 445: authmethods_get(Authctxt *authctxt)
1.1 markus 446: {
1.148 markus 447: struct sshbuf *b;
1.18 markus 448: char *list;
1.148 markus 449: int i, r;
1.1 markus 450:
1.148 markus 451: if ((b = sshbuf_new()) == NULL)
1.159 djm 452: fatal_f("sshbuf_new failed");
1.93 markus 453: for (i = 0; authmethods[i] != NULL; i++) {
1.169 ! djm 454: if (strcmp(authmethods[i]->cfg->name, "none") == 0)
1.18 markus 455: continue;
1.169 ! djm 456: if (authmethods[i]->cfg->enabled == NULL ||
! 457: *(authmethods[i]->cfg->enabled) == 0)
1.125 djm 458: continue;
1.169 ! djm 459: if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name,
1.127 markus 460: NULL))
1.125 djm 461: continue;
1.148 markus 462: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
1.169 ! djm 463: authmethods[i]->cfg->name)) != 0)
1.159 djm 464: fatal_fr(r, "buffer error");
1.1 markus 465: }
1.148 markus 466: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 467: fatal_f("sshbuf_dup_string failed");
1.148 markus 468: sshbuf_free(b);
1.18 markus 469: return list;
470: }
471:
1.66 itojun 472: static Authmethod *
1.163 djm 473: authmethod_byname(const char *name)
1.18 markus 474: {
1.93 markus 475: int i;
476:
1.163 djm 477: if (name == NULL)
478: fatal_f("NULL authentication method name");
479: for (i = 0; authmethods[i] != NULL; i++) {
1.169 ! djm 480: if (strcmp(name, authmethods[i]->cfg->name) == 0 ||
! 481: (authmethods[i]->cfg->synonym != NULL &&
! 482: strcmp(name, authmethods[i]->cfg->synonym) == 0))
1.163 djm 483: return authmethods[i];
484: }
485: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 486: return NULL;
1.163 djm 487: }
488:
489: static Authmethod *
490: authmethod_lookup(Authctxt *authctxt, const char *name)
491: {
492: Authmethod *method;
493:
494: if ((method = authmethod_byname(name)) == NULL)
495: return NULL;
496:
1.169 ! djm 497: if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) {
1.163 djm 498: debug3_f("method %s not enabled", name);
499: return NULL;
500: }
1.169 ! djm 501: if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) {
1.163 djm 502: debug3_f("method %s not allowed "
503: "by AuthenticationMethods", name);
504: return NULL;
505: }
506: return method;
1.125 djm 507: }
508:
509: /*
510: * Prune the AuthenticationMethods supplied in the configuration, removing
511: * any methods lists that include disabled methods. Note that this might
512: * leave authctxt->num_auth_methods == 0, even when multiple required auth
513: * has been requested. For this reason, all tests for whether multiple is
514: * enabled should consult options.num_auth_methods directly.
515: */
516: int
517: auth2_setup_methods_lists(Authctxt *authctxt)
518: {
519: u_int i;
1.155 djm 520:
521: /* First, normalise away the "any" pseudo-method */
522: if (options.num_auth_methods == 1 &&
523: strcmp(options.auth_methods[0], "any") == 0) {
524: free(options.auth_methods[0]);
525: options.auth_methods[0] = NULL;
526: options.num_auth_methods = 0;
527: }
1.125 djm 528:
529: if (options.num_auth_methods == 0)
530: return 0;
1.159 djm 531: debug3_f("checking methods");
1.125 djm 532: authctxt->auth_methods = xcalloc(options.num_auth_methods,
533: sizeof(*authctxt->auth_methods));
534: authctxt->num_auth_methods = 0;
535: for (i = 0; i < options.num_auth_methods; i++) {
536: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
537: logit("Authentication methods list \"%s\" contains "
538: "disabled method, skipping",
539: options.auth_methods[i]);
540: continue;
541: }
542: debug("authentication methods list %d: %s",
543: authctxt->num_auth_methods, options.auth_methods[i]);
544: authctxt->auth_methods[authctxt->num_auth_methods++] =
545: xstrdup(options.auth_methods[i]);
546: }
547: if (authctxt->num_auth_methods == 0) {
548: error("No AuthenticationMethods left after eliminating "
549: "disabled methods");
550: return -1;
551: }
552: return 0;
553: }
554:
555: static int
1.127 markus 556: list_starts_with(const char *methods, const char *method,
557: const char *submethod)
1.125 djm 558: {
559: size_t l = strlen(method);
1.127 markus 560: int match;
561: const char *p;
1.125 djm 562:
563: if (strncmp(methods, method, l) != 0)
1.127 markus 564: return MATCH_NONE;
565: p = methods + l;
566: match = MATCH_METHOD;
567: if (*p == ':') {
568: if (!submethod)
569: return MATCH_PARTIAL;
570: l = strlen(submethod);
571: p += 1;
572: if (strncmp(submethod, p, l))
573: return MATCH_NONE;
574: p += l;
575: match = MATCH_BOTH;
576: }
577: if (*p != ',' && *p != '\0')
578: return MATCH_NONE;
579: return match;
1.125 djm 580: }
581:
582: /*
583: * Remove method from the start of a comma-separated list of methods.
584: * Returns 0 if the list of methods did not start with that method or 1
585: * if it did.
586: */
587: static int
1.127 markus 588: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 589: {
1.127 markus 590: char *omethods = *methods, *p;
1.125 djm 591: size_t l = strlen(method);
1.127 markus 592: int match;
1.125 djm 593:
1.127 markus 594: match = list_starts_with(omethods, method, submethod);
595: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 596: return 0;
1.127 markus 597: p = omethods + l;
598: if (submethod && match == MATCH_BOTH)
599: p += 1 + strlen(submethod); /* include colon */
600: if (*p == ',')
601: p++;
602: *methods = xstrdup(p);
1.125 djm 603: free(omethods);
604: return 1;
605: }
606:
607: /*
608: * Called after successful authentication. Will remove the successful method
609: * from the start of each list in which it occurs. If it was the last method
610: * in any list, then authentication is deemed successful.
611: * Returns 1 if the method completed any authentication list or 0 otherwise.
612: */
613: int
1.127 markus 614: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
615: const char *submethod)
1.125 djm 616: {
617: u_int i, found = 0;
618:
1.159 djm 619: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 620: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 621: if (!remove_method(&(authctxt->auth_methods[i]), method,
622: submethod))
1.125 djm 623: continue;
624: found = 1;
625: if (*authctxt->auth_methods[i] == '\0') {
626: debug2("authentication methods list %d complete", i);
627: return 1;
628: }
629: debug3("authentication methods list %d remaining: \"%s\"",
630: i, authctxt->auth_methods[i]);
631: }
632: /* This should not happen, but would be bad if it did */
633: if (!found)
1.159 djm 634: fatal_f("method not in AuthenticationMethods");
1.125 djm 635: return 0;
636: }
637:
1.143 djm 638: /* Reset method-specific information */
639: void auth2_authctxt_reset_info(Authctxt *authctxt)
640: {
641: sshkey_free(authctxt->auth_method_key);
642: free(authctxt->auth_method_info);
643: authctxt->auth_method_key = NULL;
644: authctxt->auth_method_info = NULL;
645: }
646:
647: /* Record auth method-specific information for logs */
648: void
649: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
650: {
651: va_list ap;
1.161 djm 652: int i;
1.143 djm 653:
654: free(authctxt->auth_method_info);
655: authctxt->auth_method_info = NULL;
656:
657: va_start(ap, fmt);
658: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
659: va_end(ap);
660:
1.156 deraadt 661: if (i == -1)
1.159 djm 662: fatal_f("vasprintf failed");
1.143 djm 663: }
664:
665: /*
666: * Records a public key used in authentication. This is used for logging
667: * and to ensure that the same key is not subsequently accepted again for
668: * multiple authentication.
669: */
670: void
671: auth2_record_key(Authctxt *authctxt, int authenticated,
672: const struct sshkey *key)
673: {
674: struct sshkey **tmp, *dup;
675: int r;
676:
1.150 djm 677: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 678: fatal_fr(r, "copy key");
1.143 djm 679: sshkey_free(authctxt->auth_method_key);
680: authctxt->auth_method_key = dup;
681:
682: if (!authenticated)
683: return;
684:
685: /* If authenticated, make sure we don't accept this key again */
1.150 djm 686: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 687: fatal_fr(r, "copy key");
1.143 djm 688: if (authctxt->nprev_keys >= INT_MAX ||
689: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
690: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 691: fatal_f("reallocarray failed");
1.143 djm 692: authctxt->prev_keys = tmp;
693: authctxt->prev_keys[authctxt->nprev_keys] = dup;
694: authctxt->nprev_keys++;
695:
696: }
697:
698: /* Checks whether a key has already been previously used for authentication */
699: int
700: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
701: {
702: u_int i;
703: char *fp;
704:
705: for (i = 0; i < authctxt->nprev_keys; i++) {
706: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
707: fp = sshkey_fingerprint(authctxt->prev_keys[i],
708: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 709: debug3_f("key already used: %s %s",
1.143 djm 710: sshkey_type(authctxt->prev_keys[i]),
711: fp == NULL ? "UNKNOWN" : fp);
712: free(fp);
713: return 1;
714: }
715: }
716: return 0;
717: }
718:
719: /*
720: * Updates authctxt->session_info with details of authentication. Should be
721: * whenever an authentication method succeeds.
722: */
723: void
724: auth2_update_session_info(Authctxt *authctxt, const char *method,
725: const char *submethod)
726: {
727: int r;
728:
729: if (authctxt->session_info == NULL) {
730: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 731: fatal_f("sshbuf_new");
1.143 djm 732: }
733:
734: /* Append method[/submethod] */
735: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
736: method, submethod == NULL ? "" : "/",
737: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 738: fatal_fr(r, "append method");
1.143 djm 739:
740: /* Append key if present */
741: if (authctxt->auth_method_key != NULL) {
742: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
743: (r = sshkey_format_text(authctxt->auth_method_key,
744: authctxt->session_info)) != 0)
1.159 djm 745: fatal_fr(r, "append key");
1.143 djm 746: }
747:
748: if (authctxt->auth_method_info != NULL) {
749: /* Ensure no ambiguity here */
750: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 751: fatal_f("auth_method_info contains \\n");
1.143 djm 752: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
753: (r = sshbuf_putf(authctxt->session_info, "%s",
754: authctxt->auth_method_info)) != 0) {
1.159 djm 755: fatal_fr(r, "append method info");
1.143 djm 756: }
757: }
758: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 759: fatal_fr(r, "append");
1.143 djm 760: }
1.117 djm 761:
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