Annotation of src/usr.bin/ssh/auth2.c, Revision 1.167
1.167 ! djm 1: /* $OpenBSD: auth2.c,v 1.166 2023/03/08 04:43:12 guenther Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
1.14 deraadt 25:
1.111 stevesk 26: #include <sys/types.h>
1.117 djm 27: #include <sys/stat.h>
28: #include <sys/uio.h>
1.111 stevesk 29:
1.117 djm 30: #include <fcntl.h>
1.143 djm 31: #include <limits.h>
1.111 stevesk 32: #include <pwd.h>
1.121 dtucker 33: #include <stdarg.h>
1.112 stevesk 34: #include <string.h>
1.117 djm 35: #include <unistd.h>
1.151 djm 36: #include <time.h>
1.1 markus 37:
1.157 djm 38: #include "stdlib.h"
1.117 djm 39: #include "atomicio.h"
1.113 deraadt 40: #include "xmalloc.h"
1.32 markus 41: #include "ssh2.h"
1.1 markus 42: #include "packet.h"
1.32 markus 43: #include "log.h"
1.148 markus 44: #include "sshbuf.h"
1.132 millert 45: #include "misc.h"
1.1 markus 46: #include "servconf.h"
1.149 markus 47: #include "sshkey.h"
1.113 deraadt 48: #include "hostfile.h"
1.1 markus 49: #include "auth.h"
50: #include "dispatch.h"
1.29 markus 51: #include "pathnames.h"
1.100 markus 52: #ifdef GSSAPI
53: #include "ssh-gss.h"
54: #endif
1.113 deraadt 55: #include "monitor_wrap.h"
1.143 djm 56: #include "ssherr.h"
1.146 dtucker 57: #include "digest.h"
1.152 djm 58:
1.1 markus 59: /* import */
60: extern ServerOptions options;
61:
1.93 markus 62: /* methods */
63:
64: extern Authmethod method_none;
65: extern Authmethod method_pubkey;
66: extern Authmethod method_passwd;
67: extern Authmethod method_kbdint;
68: extern Authmethod method_hostbased;
1.100 markus 69: #ifdef GSSAPI
70: extern Authmethod method_gssapi;
71: #endif
1.93 markus 72:
73: Authmethod *authmethods[] = {
74: &method_none,
75: &method_pubkey,
1.100 markus 76: #ifdef GSSAPI
77: &method_gssapi,
78: #endif
1.93 markus 79: &method_passwd,
80: &method_kbdint,
81: &method_hostbased,
82: NULL
1.18 markus 83: };
84:
1.1 markus 85: /* protocol */
86:
1.139 markus 87: static int input_service_request(int, u_int32_t, struct ssh *);
88: static int input_userauth_request(int, u_int32_t, struct ssh *);
1.1 markus 89:
90: /* helper */
1.163 djm 91: static Authmethod *authmethod_byname(const char *);
1.125 djm 92: static Authmethod *authmethod_lookup(Authctxt *, const char *);
93: static char *authmethods_get(Authctxt *authctxt);
1.127 markus 94:
95: #define MATCH_NONE 0 /* method or submethod mismatch */
96: #define MATCH_METHOD 1 /* method matches (no submethod specified) */
97: #define MATCH_BOTH 2 /* method and submethod match */
98: #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
99: static int list_starts_with(const char *, const char *, const char *);
1.1 markus 100:
1.117 djm 101: char *
102: auth2_read_banner(void)
103: {
104: struct stat st;
105: char *banner = NULL;
106: size_t len, n;
107: int fd;
108:
109: if ((fd = open(options.banner, O_RDONLY)) == -1)
110: return (NULL);
111: if (fstat(fd, &st) == -1) {
112: close(fd);
113: return (NULL);
114: }
1.124 djm 115: if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
1.117 djm 116: close(fd);
117: return (NULL);
118: }
119:
120: len = (size_t)st.st_size; /* truncate */
121: banner = xmalloc(len + 1);
122: n = atomicio(read, fd, banner, len);
123: close(fd);
124:
125: if (n != len) {
1.128 djm 126: free(banner);
1.117 djm 127: return (NULL);
128: }
129: banner[n] = '\0';
130:
131: return (banner);
132: }
133:
134: static void
1.153 djm 135: userauth_banner(struct ssh *ssh)
1.117 djm 136: {
137: char *banner = NULL;
1.153 djm 138: int r;
1.117 djm 139:
1.144 djm 140: if (options.banner == NULL)
1.117 djm 141: return;
142:
143: if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
144: goto done;
145:
1.153 djm 146: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
147: (r = sshpkt_put_cstring(ssh, banner)) != 0 ||
148: (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
149: (r = sshpkt_send(ssh)) != 0)
1.159 djm 150: fatal_fr(r, "send packet");
1.117 djm 151: debug("userauth_banner: sent");
152: done:
1.128 djm 153: free(banner);
1.117 djm 154: }
155:
1.1 markus 156: /*
1.18 markus 157: * loop until authctxt->success == TRUE
1.1 markus 158: */
1.103 markus 159: void
1.153 djm 160: do_authentication2(struct ssh *ssh)
1.1 markus 161: {
1.153 djm 162: Authctxt *authctxt = ssh->authctxt;
163:
1.140 markus 164: ssh_dispatch_init(ssh, &dispatch_protocol_error);
165: ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.142 markus 166: ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
1.138 markus 167: ssh->authctxt = NULL;
1.1 markus 168: }
169:
1.135 markus 170: static int
1.139 markus 171: input_service_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 172: {
1.138 markus 173: Authctxt *authctxt = ssh->authctxt;
1.153 djm 174: char *service = NULL;
175: int r, acceptit = 0;
176:
177: if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
178: (r = sshpkt_get_end(ssh)) != 0)
179: goto out;
1.1 markus 180:
1.18 markus 181: if (authctxt == NULL)
182: fatal("input_service_request: no authctxt");
183:
1.1 markus 184: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 185: if (!authctxt->success) {
1.94 deraadt 186: acceptit = 1;
1.1 markus 187: /* now we can handle user-auth requests */
1.153 djm 188: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
189: &input_userauth_request);
1.1 markus 190: }
191: }
192: /* XXX all other service requests are denied */
193:
1.94 deraadt 194: if (acceptit) {
1.153 djm 195: if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
196: (r = sshpkt_put_cstring(ssh, service)) != 0 ||
197: (r = sshpkt_send(ssh)) != 0 ||
198: (r = ssh_packet_write_wait(ssh)) != 0)
199: goto out;
1.1 markus 200: } else {
201: debug("bad service request %s", service);
1.153 djm 202: ssh_packet_disconnect(ssh, "bad service request %s", service);
1.1 markus 203: }
1.153 djm 204: r = 0;
205: out:
1.128 djm 206: free(service);
1.158 markus 207: return r;
1.1 markus 208: }
209:
1.146 dtucker 210: #define MIN_FAIL_DELAY_SECONDS 0.005
1.167 ! djm 211: #define MAX_FAIL_DELAY_SECONDS 5.0
1.146 dtucker 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:
1.167 ! djm 237: if (elapsed > MAX_FAIL_DELAY_SECONDS) {
! 238: debug3_f("elapsed %0.3lfms exceeded the max delay "
! 239: "requested %0.3lfms)", elapsed*1000, req*1000);
! 240: return;
! 241: }
! 242:
1.146 dtucker 243: /* if we've already passed the requested time, scale up */
244: while ((remain = seconds - elapsed) < 0.0)
245: seconds *= 2;
246:
247: ts.tv_sec = remain;
248: ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
1.159 djm 249: debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
250: elapsed*1000, remain*1000, req*1000);
1.146 dtucker 251: nanosleep(&ts, NULL);
252: }
253:
1.135 markus 254: static int
1.139 markus 255: input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
1.1 markus 256: {
1.138 markus 257: Authctxt *authctxt = ssh->authctxt;
1.18 markus 258: Authmethod *m = NULL;
1.153 djm 259: char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
260: int r, authenticated = 0;
1.146 dtucker 261: double tstart = monotime_double();
1.1 markus 262:
1.18 markus 263: if (authctxt == NULL)
264: fatal("input_userauth_request: no authctxt");
1.1 markus 265:
1.153 djm 266: if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
267: (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
268: (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
269: goto out;
1.1 markus 270: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 271: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 272:
1.28 markus 273: if ((style = strchr(user, ':')) != NULL)
274: *style++ = 0;
275:
1.164 djm 276: if (authctxt->attempt >= 1024)
277: auth_maxtries_exceeded(ssh);
1.36 stevesk 278: if (authctxt->attempt++ == 0) {
1.18 markus 279: /* setup auth context */
1.154 djm 280: authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
1.89 markus 281: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 282: authctxt->valid = 1;
1.159 djm 283: debug2_f("setting up authctxt for %s", user);
1.18 markus 284: } else {
1.164 djm 285: authctxt->valid = 0;
1.137 djm 286: /* Invalid user, fake password information */
1.102 markus 287: authctxt->pw = fakepw();
1.18 markus 288: }
1.137 djm 289: ssh_packet_set_log_preamble(ssh, "%suser %s",
290: authctxt->valid ? "authenticating " : "invalid ", user);
1.106 djm 291: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 292: use_privsep ? " [net]" : "");
1.18 markus 293: authctxt->user = xstrdup(user);
294: authctxt->service = xstrdup(service);
1.62 markus 295: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 296: if (use_privsep)
297: mm_inform_authserv(service, style);
1.153 djm 298: userauth_banner(ssh);
1.125 djm 299: if (auth2_setup_methods_lists(authctxt) != 0)
1.153 djm 300: ssh_packet_disconnect(ssh,
301: "no authentication methods enabled");
1.62 markus 302: } else if (strcmp(user, authctxt->user) != 0 ||
303: strcmp(service, authctxt->service) != 0) {
1.153 djm 304: ssh_packet_disconnect(ssh, "Change of username or service "
305: "not allowed: (%s,%s) -> (%s,%s)",
1.62 markus 306: authctxt->user, authctxt->service, user, service);
1.1 markus 307: }
1.28 markus 308: /* reset state */
1.140 markus 309: auth2_challenge_stop(ssh);
1.100 markus 310:
311: #ifdef GSSAPI
1.120 djm 312: /* XXX move to auth2_gssapi_stop() */
1.140 markus 313: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
314: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.100 markus 315: #endif
316:
1.143 djm 317: auth2_authctxt_reset_info(authctxt);
1.28 markus 318: authctxt->postponed = 0;
1.123 djm 319: authctxt->server_caused_failure = 0;
1.18 markus 320:
1.28 markus 321: /* try to authenticate user */
1.125 djm 322: m = authmethod_lookup(authctxt, method);
1.117 djm 323: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 324: debug2("input_userauth_request: try method %s", method);
1.162 djm 325: authenticated = m->userauth(ssh, method);
1.18 markus 326: }
1.167 ! djm 327: if (!authctxt->authenticated && strcmp(method, "none") != 0)
1.146 dtucker 328: ensure_minimum_time_since(tstart,
329: user_specific_delay(authctxt->user));
1.140 markus 330: userauth_finish(ssh, authenticated, method, NULL);
1.153 djm 331: r = 0;
332: out:
1.128 djm 333: free(service);
334: free(user);
335: free(method);
1.153 djm 336: return r;
1.49 markus 337: }
338:
339: void
1.162 djm 340: userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
1.126 djm 341: const char *submethod)
1.49 markus 342: {
1.140 markus 343: Authctxt *authctxt = ssh->authctxt;
1.162 djm 344: Authmethod *m = NULL;
345: const char *method = packet_method;
1.60 markus 346: char *methods;
1.153 djm 347: int r, partial = 0;
1.60 markus 348:
1.162 djm 349: if (authenticated) {
350: if (!authctxt->valid) {
351: fatal("INTERNAL ERROR: authenticated invalid user %s",
352: authctxt->user);
353: }
354: if (authctxt->postponed)
355: fatal("INTERNAL ERROR: authenticated and postponed");
1.163 djm 356: /* prefer primary authmethod name to possible synonym */
357: if ((m = authmethod_byname(method)) == NULL)
1.162 djm 358: fatal("INTERNAL ERROR: bad method %s", method);
1.163 djm 359: method = m->name;
1.162 djm 360: }
1.18 markus 361:
362: /* Special handling for root */
1.96 markus 363: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.145 djm 364: !auth_root_allowed(ssh, method))
1.3 markus 365: authenticated = 0;
366:
1.125 djm 367: if (authenticated && options.num_auth_methods != 0) {
1.127 markus 368: if (!auth2_update_methods_lists(authctxt, method, submethod)) {
1.125 djm 369: authenticated = 0;
370: partial = 1;
371: }
372: }
1.126 djm 373:
374: /* Log before sending the reply */
1.154 djm 375: auth_log(ssh, authenticated, partial, method, submethod);
1.126 djm 376:
1.143 djm 377: /* Update information exposed to session */
378: if (authenticated || partial)
379: auth2_update_session_info(authctxt, method, submethod);
380:
1.126 djm 381: if (authctxt->postponed)
382: return;
1.125 djm 383:
1.60 markus 384: if (authenticated == 1) {
385: /* turn off userauth */
1.153 djm 386: ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
387: &dispatch_protocol_ignore);
388: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
389: (r = sshpkt_send(ssh)) != 0 ||
390: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 391: fatal_fr(r, "send success packet");
1.60 markus 392: /* now we can break out */
393: authctxt->success = 1;
1.137 djm 394: ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
1.60 markus 395: } else {
1.119 djm 396: /* Allow initial try of "none" auth without failure penalty */
1.133 djm 397: if (!partial && !authctxt->server_caused_failure &&
1.123 djm 398: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 399: authctxt->failures++;
400: if (authctxt->failures >= options.max_authtries)
1.154 djm 401: auth_maxtries_exceeded(ssh);
1.125 djm 402: methods = authmethods_get(authctxt);
1.159 djm 403: debug3_f("failure partial=%d next methods=\"%s\"",
1.125 djm 404: partial, methods);
1.153 djm 405: if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
406: (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
407: (r = sshpkt_put_u8(ssh, partial)) != 0 ||
408: (r = sshpkt_send(ssh)) != 0 ||
409: (r = ssh_packet_write_wait(ssh)) != 0)
1.159 djm 410: fatal_fr(r, "send failure packet");
1.128 djm 411: free(methods);
1.60 markus 412: }
1.1 markus 413: }
1.18 markus 414:
1.125 djm 415: /*
416: * Checks whether method is allowed by at least one AuthenticationMethods
417: * methods list. Returns 1 if allowed, or no methods lists configured.
418: * 0 otherwise.
419: */
1.127 markus 420: int
421: auth2_method_allowed(Authctxt *authctxt, const char *method,
422: const char *submethod)
1.125 djm 423: {
424: u_int i;
425:
426: /*
427: * NB. authctxt->num_auth_methods might be zero as a result of
428: * auth2_setup_methods_lists(), so check the configuration.
429: */
430: if (options.num_auth_methods == 0)
431: return 1;
432: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 433: if (list_starts_with(authctxt->auth_methods[i], method,
434: submethod) != MATCH_NONE)
1.125 djm 435: return 1;
436: }
437: return 0;
438: }
439:
1.67 stevesk 440: static char *
1.125 djm 441: authmethods_get(Authctxt *authctxt)
1.1 markus 442: {
1.148 markus 443: struct sshbuf *b;
1.18 markus 444: char *list;
1.148 markus 445: int i, r;
1.1 markus 446:
1.148 markus 447: if ((b = sshbuf_new()) == NULL)
1.159 djm 448: fatal_f("sshbuf_new failed");
1.93 markus 449: for (i = 0; authmethods[i] != NULL; i++) {
450: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 451: continue;
1.125 djm 452: if (authmethods[i]->enabled == NULL ||
453: *(authmethods[i]->enabled) == 0)
454: continue;
1.127 markus 455: if (!auth2_method_allowed(authctxt, authmethods[i]->name,
456: NULL))
1.125 djm 457: continue;
1.148 markus 458: if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
459: authmethods[i]->name)) != 0)
1.159 djm 460: fatal_fr(r, "buffer error");
1.1 markus 461: }
1.148 markus 462: if ((list = sshbuf_dup_string(b)) == NULL)
1.159 djm 463: fatal_f("sshbuf_dup_string failed");
1.148 markus 464: sshbuf_free(b);
1.18 markus 465: return list;
466: }
467:
1.66 itojun 468: static Authmethod *
1.163 djm 469: authmethod_byname(const char *name)
1.18 markus 470: {
1.93 markus 471: int i;
472:
1.163 djm 473: if (name == NULL)
474: fatal_f("NULL authentication method name");
475: for (i = 0; authmethods[i] != NULL; i++) {
476: if (strcmp(name, authmethods[i]->name) == 0 ||
477: (authmethods[i]->synonym != NULL &&
478: strcmp(name, authmethods[i]->synonym) == 0))
479: return authmethods[i];
480: }
481: debug_f("unrecognized authentication method name: %s", name);
1.18 markus 482: return NULL;
1.163 djm 483: }
484:
485: static Authmethod *
486: authmethod_lookup(Authctxt *authctxt, const char *name)
487: {
488: Authmethod *method;
489:
490: if ((method = authmethod_byname(name)) == NULL)
491: return NULL;
492:
493: if (method->enabled == NULL || *(method->enabled) == 0) {
494: debug3_f("method %s not enabled", name);
495: return NULL;
496: }
497: if (!auth2_method_allowed(authctxt, method->name, NULL)) {
498: debug3_f("method %s not allowed "
499: "by AuthenticationMethods", name);
500: return NULL;
501: }
502: return method;
1.1 markus 503: }
1.125 djm 504:
505: /*
506: * Check a comma-separated list of methods for validity. Is need_enable is
507: * non-zero, then also require that the methods are enabled.
508: * Returns 0 on success or -1 if the methods list is invalid.
509: */
510: int
511: auth2_methods_valid(const char *_methods, int need_enable)
512: {
1.127 markus 513: char *methods, *omethods, *method, *p;
1.125 djm 514: u_int i, found;
515: int ret = -1;
516:
517: if (*_methods == '\0') {
518: error("empty authentication method list");
519: return -1;
520: }
521: omethods = methods = xstrdup(_methods);
522: while ((method = strsep(&methods, ",")) != NULL) {
523: for (found = i = 0; !found && authmethods[i] != NULL; i++) {
1.127 markus 524: if ((p = strchr(method, ':')) != NULL)
525: *p = '\0';
1.125 djm 526: if (strcmp(method, authmethods[i]->name) != 0)
527: continue;
528: if (need_enable) {
529: if (authmethods[i]->enabled == NULL ||
530: *(authmethods[i]->enabled) == 0) {
531: error("Disabled method \"%s\" in "
532: "AuthenticationMethods list \"%s\"",
533: method, _methods);
534: goto out;
535: }
536: }
537: found = 1;
538: break;
539: }
540: if (!found) {
541: error("Unknown authentication method \"%s\" in list",
542: method);
543: goto out;
544: }
545: }
546: ret = 0;
547: out:
548: free(omethods);
549: return ret;
550: }
551:
552: /*
553: * Prune the AuthenticationMethods supplied in the configuration, removing
554: * any methods lists that include disabled methods. Note that this might
555: * leave authctxt->num_auth_methods == 0, even when multiple required auth
556: * has been requested. For this reason, all tests for whether multiple is
557: * enabled should consult options.num_auth_methods directly.
558: */
559: int
560: auth2_setup_methods_lists(Authctxt *authctxt)
561: {
562: u_int i;
1.155 djm 563:
564: /* First, normalise away the "any" pseudo-method */
565: if (options.num_auth_methods == 1 &&
566: strcmp(options.auth_methods[0], "any") == 0) {
567: free(options.auth_methods[0]);
568: options.auth_methods[0] = NULL;
569: options.num_auth_methods = 0;
570: }
1.125 djm 571:
572: if (options.num_auth_methods == 0)
573: return 0;
1.159 djm 574: debug3_f("checking methods");
1.125 djm 575: authctxt->auth_methods = xcalloc(options.num_auth_methods,
576: sizeof(*authctxt->auth_methods));
577: authctxt->num_auth_methods = 0;
578: for (i = 0; i < options.num_auth_methods; i++) {
579: if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
580: logit("Authentication methods list \"%s\" contains "
581: "disabled method, skipping",
582: options.auth_methods[i]);
583: continue;
584: }
585: debug("authentication methods list %d: %s",
586: authctxt->num_auth_methods, options.auth_methods[i]);
587: authctxt->auth_methods[authctxt->num_auth_methods++] =
588: xstrdup(options.auth_methods[i]);
589: }
590: if (authctxt->num_auth_methods == 0) {
591: error("No AuthenticationMethods left after eliminating "
592: "disabled methods");
593: return -1;
594: }
595: return 0;
596: }
597:
598: static int
1.127 markus 599: list_starts_with(const char *methods, const char *method,
600: const char *submethod)
1.125 djm 601: {
602: size_t l = strlen(method);
1.127 markus 603: int match;
604: const char *p;
1.125 djm 605:
606: if (strncmp(methods, method, l) != 0)
1.127 markus 607: return MATCH_NONE;
608: p = methods + l;
609: match = MATCH_METHOD;
610: if (*p == ':') {
611: if (!submethod)
612: return MATCH_PARTIAL;
613: l = strlen(submethod);
614: p += 1;
615: if (strncmp(submethod, p, l))
616: return MATCH_NONE;
617: p += l;
618: match = MATCH_BOTH;
619: }
620: if (*p != ',' && *p != '\0')
621: return MATCH_NONE;
622: return match;
1.125 djm 623: }
624:
625: /*
626: * Remove method from the start of a comma-separated list of methods.
627: * Returns 0 if the list of methods did not start with that method or 1
628: * if it did.
629: */
630: static int
1.127 markus 631: remove_method(char **methods, const char *method, const char *submethod)
1.125 djm 632: {
1.127 markus 633: char *omethods = *methods, *p;
1.125 djm 634: size_t l = strlen(method);
1.127 markus 635: int match;
1.125 djm 636:
1.127 markus 637: match = list_starts_with(omethods, method, submethod);
638: if (match != MATCH_METHOD && match != MATCH_BOTH)
1.125 djm 639: return 0;
1.127 markus 640: p = omethods + l;
641: if (submethod && match == MATCH_BOTH)
642: p += 1 + strlen(submethod); /* include colon */
643: if (*p == ',')
644: p++;
645: *methods = xstrdup(p);
1.125 djm 646: free(omethods);
647: return 1;
648: }
649:
650: /*
651: * Called after successful authentication. Will remove the successful method
652: * from the start of each list in which it occurs. If it was the last method
653: * in any list, then authentication is deemed successful.
654: * Returns 1 if the method completed any authentication list or 0 otherwise.
655: */
656: int
1.127 markus 657: auth2_update_methods_lists(Authctxt *authctxt, const char *method,
658: const char *submethod)
1.125 djm 659: {
660: u_int i, found = 0;
661:
1.159 djm 662: debug3_f("updating methods list after \"%s\"", method);
1.125 djm 663: for (i = 0; i < authctxt->num_auth_methods; i++) {
1.127 markus 664: if (!remove_method(&(authctxt->auth_methods[i]), method,
665: submethod))
1.125 djm 666: continue;
667: found = 1;
668: if (*authctxt->auth_methods[i] == '\0') {
669: debug2("authentication methods list %d complete", i);
670: return 1;
671: }
672: debug3("authentication methods list %d remaining: \"%s\"",
673: i, authctxt->auth_methods[i]);
674: }
675: /* This should not happen, but would be bad if it did */
676: if (!found)
1.159 djm 677: fatal_f("method not in AuthenticationMethods");
1.125 djm 678: return 0;
679: }
680:
1.143 djm 681: /* Reset method-specific information */
682: void auth2_authctxt_reset_info(Authctxt *authctxt)
683: {
684: sshkey_free(authctxt->auth_method_key);
685: free(authctxt->auth_method_info);
686: authctxt->auth_method_key = NULL;
687: authctxt->auth_method_info = NULL;
688: }
689:
690: /* Record auth method-specific information for logs */
691: void
692: auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
693: {
694: va_list ap;
1.161 djm 695: int i;
1.143 djm 696:
697: free(authctxt->auth_method_info);
698: authctxt->auth_method_info = NULL;
699:
700: va_start(ap, fmt);
701: i = vasprintf(&authctxt->auth_method_info, fmt, ap);
702: va_end(ap);
703:
1.156 deraadt 704: if (i == -1)
1.159 djm 705: fatal_f("vasprintf failed");
1.143 djm 706: }
707:
708: /*
709: * Records a public key used in authentication. This is used for logging
710: * and to ensure that the same key is not subsequently accepted again for
711: * multiple authentication.
712: */
713: void
714: auth2_record_key(Authctxt *authctxt, int authenticated,
715: const struct sshkey *key)
716: {
717: struct sshkey **tmp, *dup;
718: int r;
719:
1.150 djm 720: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 721: fatal_fr(r, "copy key");
1.143 djm 722: sshkey_free(authctxt->auth_method_key);
723: authctxt->auth_method_key = dup;
724:
725: if (!authenticated)
726: return;
727:
728: /* If authenticated, make sure we don't accept this key again */
1.150 djm 729: if ((r = sshkey_from_private(key, &dup)) != 0)
1.159 djm 730: fatal_fr(r, "copy key");
1.143 djm 731: if (authctxt->nprev_keys >= INT_MAX ||
732: (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
733: authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
1.159 djm 734: fatal_f("reallocarray failed");
1.143 djm 735: authctxt->prev_keys = tmp;
736: authctxt->prev_keys[authctxt->nprev_keys] = dup;
737: authctxt->nprev_keys++;
738:
739: }
740:
741: /* Checks whether a key has already been previously used for authentication */
742: int
743: auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
744: {
745: u_int i;
746: char *fp;
747:
748: for (i = 0; i < authctxt->nprev_keys; i++) {
749: if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
750: fp = sshkey_fingerprint(authctxt->prev_keys[i],
751: options.fingerprint_hash, SSH_FP_DEFAULT);
1.159 djm 752: debug3_f("key already used: %s %s",
1.143 djm 753: sshkey_type(authctxt->prev_keys[i]),
754: fp == NULL ? "UNKNOWN" : fp);
755: free(fp);
756: return 1;
757: }
758: }
759: return 0;
760: }
761:
762: /*
763: * Updates authctxt->session_info with details of authentication. Should be
764: * whenever an authentication method succeeds.
765: */
766: void
767: auth2_update_session_info(Authctxt *authctxt, const char *method,
768: const char *submethod)
769: {
770: int r;
771:
772: if (authctxt->session_info == NULL) {
773: if ((authctxt->session_info = sshbuf_new()) == NULL)
1.159 djm 774: fatal_f("sshbuf_new");
1.143 djm 775: }
776:
777: /* Append method[/submethod] */
778: if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
779: method, submethod == NULL ? "" : "/",
780: submethod == NULL ? "" : submethod)) != 0)
1.159 djm 781: fatal_fr(r, "append method");
1.143 djm 782:
783: /* Append key if present */
784: if (authctxt->auth_method_key != NULL) {
785: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
786: (r = sshkey_format_text(authctxt->auth_method_key,
787: authctxt->session_info)) != 0)
1.159 djm 788: fatal_fr(r, "append key");
1.143 djm 789: }
790:
791: if (authctxt->auth_method_info != NULL) {
792: /* Ensure no ambiguity here */
793: if (strchr(authctxt->auth_method_info, '\n') != NULL)
1.159 djm 794: fatal_f("auth_method_info contains \\n");
1.143 djm 795: if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
796: (r = sshbuf_putf(authctxt->session_info, "%s",
797: authctxt->auth_method_info)) != 0) {
1.159 djm 798: fatal_fr(r, "append method info");
1.143 djm 799: }
800: }
801: if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
1.159 djm 802: fatal_fr(r, "append");
1.143 djm 803: }
1.117 djm 804:
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