Annotation of src/usr.bin/ssh/auth2.c, Revision 1.123
1.123 ! djm 1: /* $OpenBSD: auth2.c,v 1.122 2010/08/31 09:58:37 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:
27: #include <sys/types.h>
1.117 djm 28: #include <sys/stat.h>
29: #include <sys/uio.h>
1.111 stevesk 30:
1.117 djm 31: #include <fcntl.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>
1.1 markus 36:
1.117 djm 37: #include "atomicio.h"
1.113 deraadt 38: #include "xmalloc.h"
1.32 markus 39: #include "ssh2.h"
1.1 markus 40: #include "packet.h"
1.32 markus 41: #include "log.h"
1.113 deraadt 42: #include "buffer.h"
1.1 markus 43: #include "servconf.h"
44: #include "compat.h"
1.113 deraadt 45: #include "key.h"
46: #include "hostfile.h"
1.1 markus 47: #include "auth.h"
48: #include "dispatch.h"
1.29 markus 49: #include "pathnames.h"
1.100 markus 50: #ifdef GSSAPI
51: #include "ssh-gss.h"
52: #endif
1.113 deraadt 53: #include "monitor_wrap.h"
1.100 markus 54:
1.1 markus 55: /* import */
56: extern ServerOptions options;
1.23 markus 57: extern u_char *session_id2;
1.99 markus 58: extern u_int session_id2_len;
1.1 markus 59:
1.93 markus 60: /* methods */
61:
62: extern Authmethod method_none;
63: extern Authmethod method_pubkey;
64: extern Authmethod method_passwd;
65: extern Authmethod method_kbdint;
66: extern Authmethod method_hostbased;
1.100 markus 67: #ifdef GSSAPI
68: extern Authmethod method_gssapi;
69: #endif
1.120 djm 70: #ifdef JPAKE
71: extern Authmethod method_jpake;
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
1.120 djm 80: #ifdef JPAKE
81: &method_jpake,
82: #endif
1.93 markus 83: &method_passwd,
84: &method_kbdint,
85: &method_hostbased,
86: NULL
1.18 markus 87: };
88:
1.1 markus 89: /* protocol */
90:
1.80 markus 91: static void input_service_request(int, u_int32_t, void *);
92: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 93:
94: /* helper */
1.66 itojun 95: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 96: static char *authmethods_get(void);
1.1 markus 97:
1.117 djm 98: char *
99: auth2_read_banner(void)
100: {
101: struct stat st;
102: char *banner = NULL;
103: size_t len, n;
104: int fd;
105:
106: if ((fd = open(options.banner, O_RDONLY)) == -1)
107: return (NULL);
108: if (fstat(fd, &st) == -1) {
109: close(fd);
110: return (NULL);
111: }
112: if (st.st_size > 1*1024*1024) {
113: close(fd);
114: return (NULL);
115: }
116:
117: len = (size_t)st.st_size; /* truncate */
118: banner = xmalloc(len + 1);
119: n = atomicio(read, fd, banner, len);
120: close(fd);
121:
122: if (n != len) {
123: xfree(banner);
124: return (NULL);
125: }
126: banner[n] = '\0';
127:
128: return (banner);
129: }
130:
131: static void
132: userauth_banner(void)
133: {
134: char *banner = NULL;
135:
136: if (options.banner == NULL ||
137: strcasecmp(options.banner, "none") == 0 ||
138: (datafellows & SSH_BUG_BANNER) != 0)
139: return;
140:
141: if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
142: goto done;
143:
144: packet_start(SSH2_MSG_USERAUTH_BANNER);
145: packet_put_cstring(banner);
146: packet_put_cstring(""); /* language, unused */
147: packet_send();
148: debug("userauth_banner: sent");
149: done:
150: if (banner)
151: xfree(banner);
152: }
153:
1.1 markus 154: /*
1.18 markus 155: * loop until authctxt->success == TRUE
1.1 markus 156: */
1.103 markus 157: void
158: do_authentication2(Authctxt *authctxt)
1.1 markus 159: {
1.81 markus 160: dispatch_init(&dispatch_protocol_error);
1.1 markus 161: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 162: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 163: }
164:
1.109 deraadt 165: /*ARGSUSED*/
1.66 itojun 166: static void
1.80 markus 167: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 168: {
1.18 markus 169: Authctxt *authctxt = ctxt;
1.23 markus 170: u_int len;
1.94 deraadt 171: int acceptit = 0;
1.122 djm 172: char *service = packet_get_cstring(&len);
1.79 markus 173: packet_check_eom();
1.1 markus 174:
1.18 markus 175: if (authctxt == NULL)
176: fatal("input_service_request: no authctxt");
177:
1.1 markus 178: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 179: if (!authctxt->success) {
1.94 deraadt 180: acceptit = 1;
1.1 markus 181: /* now we can handle user-auth requests */
182: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
183: }
184: }
185: /* XXX all other service requests are denied */
186:
1.94 deraadt 187: if (acceptit) {
1.1 markus 188: packet_start(SSH2_MSG_SERVICE_ACCEPT);
189: packet_put_cstring(service);
190: packet_send();
191: packet_write_wait();
192: } else {
193: debug("bad service request %s", service);
194: packet_disconnect("bad service request %s", service);
195: }
196: xfree(service);
197: }
198:
1.109 deraadt 199: /*ARGSUSED*/
1.66 itojun 200: static void
1.80 markus 201: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 202: {
1.18 markus 203: Authctxt *authctxt = ctxt;
204: Authmethod *m = NULL;
1.28 markus 205: char *user, *service, *method, *style = NULL;
1.1 markus 206: int authenticated = 0;
207:
1.18 markus 208: if (authctxt == NULL)
209: fatal("input_userauth_request: no authctxt");
1.1 markus 210:
1.122 djm 211: user = packet_get_cstring(NULL);
212: service = packet_get_cstring(NULL);
213: method = packet_get_cstring(NULL);
1.1 markus 214: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 215: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 216:
1.28 markus 217: if ((style = strchr(user, ':')) != NULL)
218: *style++ = 0;
219:
1.36 stevesk 220: if (authctxt->attempt++ == 0) {
1.18 markus 221: /* setup auth context */
1.89 markus 222: authctxt->pw = PRIVSEP(getpwnamallow(user));
223: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 224: authctxt->valid = 1;
225: debug2("input_userauth_request: setting up authctxt for %s", user);
226: } else {
1.107 markus 227: logit("input_userauth_request: invalid user %s", user);
1.102 markus 228: authctxt->pw = fakepw();
1.18 markus 229: }
1.106 djm 230: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 231: use_privsep ? " [net]" : "");
1.18 markus 232: authctxt->user = xstrdup(user);
233: authctxt->service = xstrdup(service);
1.62 markus 234: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 235: if (use_privsep)
236: mm_inform_authserv(service, style);
1.117 djm 237: userauth_banner();
1.62 markus 238: } else if (strcmp(user, authctxt->user) != 0 ||
239: strcmp(service, authctxt->service) != 0) {
240: packet_disconnect("Change of username or service not allowed: "
241: "(%s,%s) -> (%s,%s)",
242: authctxt->user, authctxt->service, user, service);
1.1 markus 243: }
1.28 markus 244: /* reset state */
1.75 markus 245: auth2_challenge_stop(authctxt);
1.120 djm 246: #ifdef JPAKE
247: auth2_jpake_stop(authctxt);
248: #endif
1.100 markus 249:
250: #ifdef GSSAPI
1.120 djm 251: /* XXX move to auth2_gssapi_stop() */
1.100 markus 252: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
253: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
254: #endif
255:
1.28 markus 256: authctxt->postponed = 0;
1.123 ! djm 257: authctxt->server_caused_failure = 0;
1.18 markus 258:
1.28 markus 259: /* try to authenticate user */
1.18 markus 260: m = authmethod_lookup(method);
1.117 djm 261: if (m != NULL && authctxt->failures < options.max_authtries) {
1.18 markus 262: debug2("input_userauth_request: try method %s", method);
263: authenticated = m->userauth(authctxt);
264: }
1.49 markus 265: userauth_finish(authctxt, authenticated, method);
266:
267: xfree(service);
268: xfree(user);
269: xfree(method);
270: }
271:
272: void
273: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
274: {
1.60 markus 275: char *methods;
276:
1.28 markus 277: if (!authctxt->valid && authenticated)
278: fatal("INTERNAL ERROR: authenticated invalid user %s",
279: authctxt->user);
1.18 markus 280:
281: /* Special handling for root */
1.96 markus 282: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 283: !auth_root_allowed(method))
1.3 markus 284: authenticated = 0;
285:
1.18 markus 286: /* Log before sending the reply */
1.28 markus 287: auth_log(authctxt, authenticated, method, " ssh2");
288:
1.60 markus 289: if (authctxt->postponed)
290: return;
291:
292: /* XXX todo: check if multiple auth methods are needed */
293: if (authenticated == 1) {
294: /* turn off userauth */
1.81 markus 295: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 296: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
297: packet_send();
298: packet_write_wait();
299: /* now we can break out */
300: authctxt->success = 1;
301: } else {
1.119 djm 302: /* Allow initial try of "none" auth without failure penalty */
1.123 ! djm 303: if (!authctxt->server_caused_failure &&
! 304: (authctxt->attempt > 1 || strcmp(method, "none") != 0))
1.119 djm 305: authctxt->failures++;
306: if (authctxt->failures >= options.max_authtries)
1.60 markus 307: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
308: methods = authmethods_get();
309: packet_start(SSH2_MSG_USERAUTH_FAILURE);
310: packet_put_cstring(methods);
311: packet_put_char(0); /* XXX partial success, unused */
312: packet_send();
313: packet_write_wait();
314: xfree(methods);
315: }
1.1 markus 316: }
1.18 markus 317:
1.67 stevesk 318: static char *
1.18 markus 319: authmethods_get(void)
1.1 markus 320: {
1.82 markus 321: Buffer b;
1.18 markus 322: char *list;
1.93 markus 323: int i;
1.1 markus 324:
1.82 markus 325: buffer_init(&b);
1.93 markus 326: for (i = 0; authmethods[i] != NULL; i++) {
327: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 328: continue;
1.93 markus 329: if (authmethods[i]->enabled != NULL &&
330: *(authmethods[i]->enabled) != 0) {
1.82 markus 331: if (buffer_len(&b) > 0)
332: buffer_append(&b, ",", 1);
1.93 markus 333: buffer_append(&b, authmethods[i]->name,
334: strlen(authmethods[i]->name));
1.1 markus 335: }
336: }
1.82 markus 337: buffer_append(&b, "\0", 1);
338: list = xstrdup(buffer_ptr(&b));
339: buffer_free(&b);
1.18 markus 340: return list;
341: }
342:
1.66 itojun 343: static Authmethod *
1.18 markus 344: authmethod_lookup(const char *name)
345: {
1.93 markus 346: int i;
347:
1.18 markus 348: if (name != NULL)
1.93 markus 349: for (i = 0; authmethods[i] != NULL; i++)
350: if (authmethods[i]->enabled != NULL &&
351: *(authmethods[i]->enabled) != 0 &&
352: strcmp(name, authmethods[i]->name) == 0)
353: return authmethods[i];
354: debug2("Unrecognized authentication method name: %s",
355: name ? name : "NULL");
1.18 markus 356: return NULL;
1.1 markus 357: }
1.117 djm 358:
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