Annotation of src/usr.bin/ssh/auth2.c, Revision 1.114
1.114 ! dtucker 1: /* $OpenBSD: auth2.c,v 1.113 2006/08/03 03:34:41 deraadt 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>
28:
29: #include <pwd.h>
1.112 stevesk 30: #include <string.h>
1.113 deraadt 31: #include <stdarg.h>
1.1 markus 32:
1.113 deraadt 33: #include "xmalloc.h"
1.32 markus 34: #include "ssh2.h"
1.1 markus 35: #include "packet.h"
1.32 markus 36: #include "log.h"
1.113 deraadt 37: #include "buffer.h"
1.1 markus 38: #include "servconf.h"
39: #include "compat.h"
1.113 deraadt 40: #include "key.h"
41: #include "hostfile.h"
1.1 markus 42: #include "auth.h"
43: #include "dispatch.h"
1.29 markus 44: #include "pathnames.h"
1.100 markus 45: #ifdef GSSAPI
46: #include "ssh-gss.h"
47: #endif
1.113 deraadt 48: #include "monitor_wrap.h"
1.100 markus 49:
1.1 markus 50: /* import */
51: extern ServerOptions options;
1.23 markus 52: extern u_char *session_id2;
1.99 markus 53: extern u_int session_id2_len;
1.1 markus 54:
1.93 markus 55: /* methods */
56:
57: extern Authmethod method_none;
58: extern Authmethod method_pubkey;
59: extern Authmethod method_passwd;
60: extern Authmethod method_kbdint;
61: extern Authmethod method_hostbased;
1.100 markus 62: #ifdef GSSAPI
63: extern Authmethod method_gssapi;
64: #endif
1.93 markus 65:
66: Authmethod *authmethods[] = {
67: &method_none,
68: &method_pubkey,
1.100 markus 69: #ifdef GSSAPI
70: &method_gssapi,
71: #endif
1.93 markus 72: &method_passwd,
73: &method_kbdint,
74: &method_hostbased,
75: NULL
1.18 markus 76: };
77:
1.1 markus 78: /* protocol */
79:
1.80 markus 80: static void input_service_request(int, u_int32_t, void *);
81: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 82:
83: /* helper */
1.66 itojun 84: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 85: static char *authmethods_get(void);
1.88 provos 86: int user_key_allowed(struct passwd *, Key *);
1.1 markus 87:
88: /*
1.18 markus 89: * loop until authctxt->success == TRUE
1.1 markus 90: */
91:
1.103 markus 92: void
93: do_authentication2(Authctxt *authctxt)
1.1 markus 94: {
1.81 markus 95: dispatch_init(&dispatch_protocol_error);
1.1 markus 96: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 97: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 98: }
99:
1.109 deraadt 100: /*ARGSUSED*/
1.66 itojun 101: static void
1.80 markus 102: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 103: {
1.18 markus 104: Authctxt *authctxt = ctxt;
1.23 markus 105: u_int len;
1.94 deraadt 106: int acceptit = 0;
1.1 markus 107: char *service = packet_get_string(&len);
1.79 markus 108: packet_check_eom();
1.1 markus 109:
1.18 markus 110: if (authctxt == NULL)
111: fatal("input_service_request: no authctxt");
112:
1.1 markus 113: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 114: if (!authctxt->success) {
1.94 deraadt 115: acceptit = 1;
1.1 markus 116: /* now we can handle user-auth requests */
117: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
118: }
119: }
120: /* XXX all other service requests are denied */
121:
1.94 deraadt 122: if (acceptit) {
1.1 markus 123: packet_start(SSH2_MSG_SERVICE_ACCEPT);
124: packet_put_cstring(service);
125: packet_send();
126: packet_write_wait();
127: } else {
128: debug("bad service request %s", service);
129: packet_disconnect("bad service request %s", service);
130: }
131: xfree(service);
132: }
133:
1.109 deraadt 134: /*ARGSUSED*/
1.66 itojun 135: static void
1.80 markus 136: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 137: {
1.18 markus 138: Authctxt *authctxt = ctxt;
139: Authmethod *m = NULL;
1.28 markus 140: char *user, *service, *method, *style = NULL;
1.1 markus 141: int authenticated = 0;
142:
1.18 markus 143: if (authctxt == NULL)
144: fatal("input_userauth_request: no authctxt");
1.1 markus 145:
1.18 markus 146: user = packet_get_string(NULL);
147: service = packet_get_string(NULL);
148: method = packet_get_string(NULL);
1.1 markus 149: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 150: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 151:
1.28 markus 152: if ((style = strchr(user, ':')) != NULL)
153: *style++ = 0;
154:
1.36 stevesk 155: if (authctxt->attempt++ == 0) {
1.18 markus 156: /* setup auth context */
1.89 markus 157: authctxt->pw = PRIVSEP(getpwnamallow(user));
158: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 159: authctxt->valid = 1;
160: debug2("input_userauth_request: setting up authctxt for %s", user);
161: } else {
1.107 markus 162: logit("input_userauth_request: invalid user %s", user);
1.102 markus 163: authctxt->pw = fakepw();
1.18 markus 164: }
1.106 djm 165: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 166: use_privsep ? " [net]" : "");
1.18 markus 167: authctxt->user = xstrdup(user);
168: authctxt->service = xstrdup(service);
1.62 markus 169: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 170: if (use_privsep)
171: mm_inform_authserv(service, style);
1.62 markus 172: } else if (strcmp(user, authctxt->user) != 0 ||
173: strcmp(service, authctxt->service) != 0) {
174: packet_disconnect("Change of username or service not allowed: "
175: "(%s,%s) -> (%s,%s)",
176: authctxt->user, authctxt->service, user, service);
1.1 markus 177: }
1.28 markus 178: /* reset state */
1.75 markus 179: auth2_challenge_stop(authctxt);
1.100 markus 180:
181: #ifdef GSSAPI
182: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
183: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
184: #endif
185:
1.28 markus 186: authctxt->postponed = 0;
1.18 markus 187:
1.28 markus 188: /* try to authenticate user */
1.18 markus 189: m = authmethod_lookup(method);
190: if (m != NULL) {
191: debug2("input_userauth_request: try method %s", method);
192: authenticated = m->userauth(authctxt);
193: }
1.49 markus 194: userauth_finish(authctxt, authenticated, method);
195:
196: xfree(service);
197: xfree(user);
198: xfree(method);
199: }
200:
201: void
202: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
203: {
1.60 markus 204: char *methods;
205:
1.28 markus 206: if (!authctxt->valid && authenticated)
207: fatal("INTERNAL ERROR: authenticated invalid user %s",
208: authctxt->user);
1.18 markus 209:
210: /* Special handling for root */
1.96 markus 211: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 212: !auth_root_allowed(method))
1.3 markus 213: authenticated = 0;
214:
1.18 markus 215: /* Log before sending the reply */
1.28 markus 216: auth_log(authctxt, authenticated, method, " ssh2");
217:
1.60 markus 218: if (authctxt->postponed)
219: return;
220:
221: /* XXX todo: check if multiple auth methods are needed */
222: if (authenticated == 1) {
223: /* turn off userauth */
1.81 markus 224: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 225: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
226: packet_send();
227: packet_write_wait();
228: /* now we can break out */
229: authctxt->success = 1;
230: } else {
1.105 dtucker 231: if (authctxt->failures++ > options.max_authtries)
1.60 markus 232: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
233: methods = authmethods_get();
234: packet_start(SSH2_MSG_USERAUTH_FAILURE);
235: packet_put_cstring(methods);
236: packet_put_char(0); /* XXX partial success, unused */
237: packet_send();
238: packet_write_wait();
239: xfree(methods);
240: }
1.1 markus 241: }
242:
1.18 markus 243: #define DELIM ","
244:
1.67 stevesk 245: static char *
1.18 markus 246: authmethods_get(void)
1.1 markus 247: {
1.82 markus 248: Buffer b;
1.18 markus 249: char *list;
1.93 markus 250: int i;
1.1 markus 251:
1.82 markus 252: buffer_init(&b);
1.93 markus 253: for (i = 0; authmethods[i] != NULL; i++) {
254: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 255: continue;
1.93 markus 256: if (authmethods[i]->enabled != NULL &&
257: *(authmethods[i]->enabled) != 0) {
1.82 markus 258: if (buffer_len(&b) > 0)
259: buffer_append(&b, ",", 1);
1.93 markus 260: buffer_append(&b, authmethods[i]->name,
261: strlen(authmethods[i]->name));
1.1 markus 262: }
263: }
1.82 markus 264: buffer_append(&b, "\0", 1);
265: list = xstrdup(buffer_ptr(&b));
266: buffer_free(&b);
1.18 markus 267: return list;
268: }
269:
1.66 itojun 270: static Authmethod *
1.18 markus 271: authmethod_lookup(const char *name)
272: {
1.93 markus 273: int i;
274:
1.18 markus 275: if (name != NULL)
1.93 markus 276: for (i = 0; authmethods[i] != NULL; i++)
277: if (authmethods[i]->enabled != NULL &&
278: *(authmethods[i]->enabled) != 0 &&
279: strcmp(name, authmethods[i]->name) == 0)
280: return authmethods[i];
281: debug2("Unrecognized authentication method name: %s",
282: name ? name : "NULL");
1.18 markus 283: return NULL;
1.1 markus 284: }
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