Annotation of src/usr.bin/ssh/auth2.c, Revision 1.103
1.1 markus 1: /*
2: * Copyright (c) 2000 Markus Friedl. All rights reserved.
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
1.14 deraadt 24:
1.1 markus 25: #include "includes.h"
1.103 ! markus 26: RCSID("$OpenBSD: auth2.c,v 1.102 2003/08/26 09:58:43 markus Exp $");
1.1 markus 27:
1.32 markus 28: #include "ssh2.h"
1.1 markus 29: #include "xmalloc.h"
30: #include "packet.h"
1.32 markus 31: #include "log.h"
1.1 markus 32: #include "servconf.h"
33: #include "compat.h"
34: #include "auth.h"
35: #include "dispatch.h"
1.29 markus 36: #include "pathnames.h"
1.88 provos 37: #include "monitor_wrap.h"
1.1 markus 38:
1.100 markus 39: #ifdef GSSAPI
40: #include "ssh-gss.h"
41: #endif
42:
1.1 markus 43: /* import */
44: extern ServerOptions options;
1.23 markus 45: extern u_char *session_id2;
1.99 markus 46: extern u_int session_id2_len;
1.1 markus 47:
1.93 markus 48: /* methods */
49:
50: extern Authmethod method_none;
51: extern Authmethod method_pubkey;
52: extern Authmethod method_passwd;
53: extern Authmethod method_kbdint;
54: extern Authmethod method_hostbased;
1.100 markus 55: #ifdef GSSAPI
56: extern Authmethod method_gssapi;
57: #endif
1.93 markus 58:
59: Authmethod *authmethods[] = {
60: &method_none,
61: &method_pubkey,
1.100 markus 62: #ifdef GSSAPI
63: &method_gssapi,
64: #endif
1.93 markus 65: &method_passwd,
66: &method_kbdint,
67: &method_hostbased,
68: NULL
1.18 markus 69: };
70:
1.1 markus 71: /* protocol */
72:
1.80 markus 73: static void input_service_request(int, u_int32_t, void *);
74: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 75:
76: /* helper */
1.66 itojun 77: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 78: static char *authmethods_get(void);
1.88 provos 79: int user_key_allowed(struct passwd *, Key *);
80: int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
1.1 markus 81:
82: /*
1.18 markus 83: * loop until authctxt->success == TRUE
1.1 markus 84: */
85:
1.103 ! markus 86: void
! 87: do_authentication2(Authctxt *authctxt)
1.1 markus 88: {
1.71 markus 89: /* challenge-response is implemented via keyboard interactive */
1.57 markus 90: if (options.challenge_response_authentication)
1.34 markus 91: options.kbd_interactive_authentication = 1;
92:
1.81 markus 93: dispatch_init(&dispatch_protocol_error);
1.1 markus 94: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 95: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 96: }
97:
1.66 itojun 98: static void
1.80 markus 99: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 100: {
1.18 markus 101: Authctxt *authctxt = ctxt;
1.23 markus 102: u_int len;
1.94 deraadt 103: int acceptit = 0;
1.1 markus 104: char *service = packet_get_string(&len);
1.79 markus 105: packet_check_eom();
1.1 markus 106:
1.18 markus 107: if (authctxt == NULL)
108: fatal("input_service_request: no authctxt");
109:
1.1 markus 110: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 111: if (!authctxt->success) {
1.94 deraadt 112: acceptit = 1;
1.1 markus 113: /* now we can handle user-auth requests */
114: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
115: }
116: }
117: /* XXX all other service requests are denied */
118:
1.94 deraadt 119: if (acceptit) {
1.1 markus 120: packet_start(SSH2_MSG_SERVICE_ACCEPT);
121: packet_put_cstring(service);
122: packet_send();
123: packet_write_wait();
124: } else {
125: debug("bad service request %s", service);
126: packet_disconnect("bad service request %s", service);
127: }
128: xfree(service);
129: }
130:
1.66 itojun 131: static void
1.80 markus 132: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 133: {
1.18 markus 134: Authctxt *authctxt = ctxt;
135: Authmethod *m = NULL;
1.28 markus 136: char *user, *service, *method, *style = NULL;
1.1 markus 137: int authenticated = 0;
138:
1.18 markus 139: if (authctxt == NULL)
140: fatal("input_userauth_request: no authctxt");
1.1 markus 141:
1.18 markus 142: user = packet_get_string(NULL);
143: service = packet_get_string(NULL);
144: method = packet_get_string(NULL);
1.1 markus 145: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 146: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 147:
1.28 markus 148: if ((style = strchr(user, ':')) != NULL)
149: *style++ = 0;
150:
1.36 stevesk 151: if (authctxt->attempt++ == 0) {
1.18 markus 152: /* setup auth context */
1.89 markus 153: authctxt->pw = PRIVSEP(getpwnamallow(user));
154: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 155: authctxt->valid = 1;
156: debug2("input_userauth_request: setting up authctxt for %s", user);
157: } else {
1.97 itojun 158: logit("input_userauth_request: illegal user %s", user);
1.102 markus 159: authctxt->pw = fakepw();
1.18 markus 160: }
1.89 markus 161: setproctitle("%s%s", authctxt->pw ? user : "unknown",
1.88 provos 162: use_privsep ? " [net]" : "");
1.18 markus 163: authctxt->user = xstrdup(user);
164: authctxt->service = xstrdup(service);
1.62 markus 165: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 166: if (use_privsep)
167: mm_inform_authserv(service, style);
1.62 markus 168: } else if (strcmp(user, authctxt->user) != 0 ||
169: strcmp(service, authctxt->service) != 0) {
170: packet_disconnect("Change of username or service not allowed: "
171: "(%s,%s) -> (%s,%s)",
172: authctxt->user, authctxt->service, user, service);
1.1 markus 173: }
1.28 markus 174: /* reset state */
1.75 markus 175: auth2_challenge_stop(authctxt);
1.100 markus 176:
177: #ifdef GSSAPI
178: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
179: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
180: #endif
181:
1.28 markus 182: authctxt->postponed = 0;
1.18 markus 183:
1.28 markus 184: /* try to authenticate user */
1.18 markus 185: m = authmethod_lookup(method);
186: if (m != NULL) {
187: debug2("input_userauth_request: try method %s", method);
188: authenticated = m->userauth(authctxt);
189: }
1.49 markus 190: userauth_finish(authctxt, authenticated, method);
191:
192: xfree(service);
193: xfree(user);
194: xfree(method);
195: }
196:
197: void
198: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
199: {
1.60 markus 200: char *methods;
201:
1.28 markus 202: if (!authctxt->valid && authenticated)
203: fatal("INTERNAL ERROR: authenticated invalid user %s",
204: authctxt->user);
1.18 markus 205:
206: /* Special handling for root */
1.96 markus 207: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 208: !auth_root_allowed(method))
1.3 markus 209: authenticated = 0;
210:
1.18 markus 211: /* Log before sending the reply */
1.28 markus 212: auth_log(authctxt, authenticated, method, " ssh2");
213:
1.60 markus 214: if (authctxt->postponed)
215: return;
216:
217: /* XXX todo: check if multiple auth methods are needed */
218: if (authenticated == 1) {
219: /* turn off userauth */
1.81 markus 220: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 221: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
222: packet_send();
223: packet_write_wait();
224: /* now we can break out */
225: authctxt->success = 1;
226: } else {
227: if (authctxt->failures++ > AUTH_FAIL_MAX)
228: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
229: methods = authmethods_get();
230: packet_start(SSH2_MSG_USERAUTH_FAILURE);
231: packet_put_cstring(methods);
232: packet_put_char(0); /* XXX partial success, unused */
233: packet_send();
234: packet_write_wait();
235: xfree(methods);
236: }
1.1 markus 237: }
238:
1.18 markus 239: #define DELIM ","
240:
1.67 stevesk 241: static char *
1.18 markus 242: authmethods_get(void)
1.1 markus 243: {
1.82 markus 244: Buffer b;
1.18 markus 245: char *list;
1.93 markus 246: int i;
1.1 markus 247:
1.82 markus 248: buffer_init(&b);
1.93 markus 249: for (i = 0; authmethods[i] != NULL; i++) {
250: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 251: continue;
1.93 markus 252: if (authmethods[i]->enabled != NULL &&
253: *(authmethods[i]->enabled) != 0) {
1.82 markus 254: if (buffer_len(&b) > 0)
255: buffer_append(&b, ",", 1);
1.93 markus 256: buffer_append(&b, authmethods[i]->name,
257: strlen(authmethods[i]->name));
1.1 markus 258: }
259: }
1.82 markus 260: buffer_append(&b, "\0", 1);
261: list = xstrdup(buffer_ptr(&b));
262: buffer_free(&b);
1.18 markus 263: return list;
264: }
265:
1.66 itojun 266: static Authmethod *
1.18 markus 267: authmethod_lookup(const char *name)
268: {
1.93 markus 269: int i;
270:
1.18 markus 271: if (name != NULL)
1.93 markus 272: for (i = 0; authmethods[i] != NULL; i++)
273: if (authmethods[i]->enabled != NULL &&
274: *(authmethods[i]->enabled) != 0 &&
275: strcmp(name, authmethods[i]->name) == 0)
276: return authmethods[i];
277: debug2("Unrecognized authentication method name: %s",
278: name ? name : "NULL");
1.18 markus 279: return NULL;
1.1 markus 280: }