Annotation of src/usr.bin/ssh/auth2.c, Revision 1.107.8.1
1.107.8.1! brad 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:
1.1 markus 26:
1.107.8.1! brad 27: #include <sys/types.h>
! 28:
! 29: #include <pwd.h>
! 30: #include <string.h>
! 31: #include <stdarg.h>
! 32:
1.1 markus 33: #include "xmalloc.h"
1.107.8.1! brad 34: #include "ssh2.h"
1.1 markus 35: #include "packet.h"
1.32 markus 36: #include "log.h"
1.107.8.1! brad 37: #include "buffer.h"
1.1 markus 38: #include "servconf.h"
39: #include "compat.h"
1.107.8.1! brad 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
1.107.8.1! brad 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: {
1.71 markus 95: /* challenge-response is implemented via keyboard interactive */
1.57 markus 96: if (options.challenge_response_authentication)
1.34 markus 97: options.kbd_interactive_authentication = 1;
98:
1.81 markus 99: dispatch_init(&dispatch_protocol_error);
1.1 markus 100: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 101: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 102: }
103:
1.107.8.1! brad 104: /*ARGSUSED*/
1.66 itojun 105: static void
1.80 markus 106: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 107: {
1.18 markus 108: Authctxt *authctxt = ctxt;
1.23 markus 109: u_int len;
1.94 deraadt 110: int acceptit = 0;
1.1 markus 111: char *service = packet_get_string(&len);
1.79 markus 112: packet_check_eom();
1.1 markus 113:
1.18 markus 114: if (authctxt == NULL)
115: fatal("input_service_request: no authctxt");
116:
1.1 markus 117: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 118: if (!authctxt->success) {
1.94 deraadt 119: acceptit = 1;
1.1 markus 120: /* now we can handle user-auth requests */
121: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
122: }
123: }
124: /* XXX all other service requests are denied */
125:
1.94 deraadt 126: if (acceptit) {
1.1 markus 127: packet_start(SSH2_MSG_SERVICE_ACCEPT);
128: packet_put_cstring(service);
129: packet_send();
130: packet_write_wait();
131: } else {
132: debug("bad service request %s", service);
133: packet_disconnect("bad service request %s", service);
134: }
135: xfree(service);
136: }
137:
1.107.8.1! brad 138: /*ARGSUSED*/
1.66 itojun 139: static void
1.80 markus 140: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 141: {
1.18 markus 142: Authctxt *authctxt = ctxt;
143: Authmethod *m = NULL;
1.28 markus 144: char *user, *service, *method, *style = NULL;
1.1 markus 145: int authenticated = 0;
146:
1.18 markus 147: if (authctxt == NULL)
148: fatal("input_userauth_request: no authctxt");
1.1 markus 149:
1.18 markus 150: user = packet_get_string(NULL);
151: service = packet_get_string(NULL);
152: method = packet_get_string(NULL);
1.1 markus 153: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 154: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 155:
1.28 markus 156: if ((style = strchr(user, ':')) != NULL)
157: *style++ = 0;
158:
1.36 stevesk 159: if (authctxt->attempt++ == 0) {
1.18 markus 160: /* setup auth context */
1.89 markus 161: authctxt->pw = PRIVSEP(getpwnamallow(user));
162: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 163: authctxt->valid = 1;
164: debug2("input_userauth_request: setting up authctxt for %s", user);
165: } else {
1.107 markus 166: logit("input_userauth_request: invalid user %s", user);
1.102 markus 167: authctxt->pw = fakepw();
1.18 markus 168: }
1.106 djm 169: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 170: use_privsep ? " [net]" : "");
1.18 markus 171: authctxt->user = xstrdup(user);
172: authctxt->service = xstrdup(service);
1.62 markus 173: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 174: if (use_privsep)
175: mm_inform_authserv(service, style);
1.62 markus 176: } else if (strcmp(user, authctxt->user) != 0 ||
177: strcmp(service, authctxt->service) != 0) {
178: packet_disconnect("Change of username or service not allowed: "
179: "(%s,%s) -> (%s,%s)",
180: authctxt->user, authctxt->service, user, service);
1.1 markus 181: }
1.28 markus 182: /* reset state */
1.75 markus 183: auth2_challenge_stop(authctxt);
1.100 markus 184:
185: #ifdef GSSAPI
186: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
187: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
188: #endif
189:
1.28 markus 190: authctxt->postponed = 0;
1.18 markus 191:
1.28 markus 192: /* try to authenticate user */
1.18 markus 193: m = authmethod_lookup(method);
194: if (m != NULL) {
195: debug2("input_userauth_request: try method %s", method);
196: authenticated = m->userauth(authctxt);
197: }
1.49 markus 198: userauth_finish(authctxt, authenticated, method);
199:
200: xfree(service);
201: xfree(user);
202: xfree(method);
203: }
204:
205: void
206: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
207: {
1.60 markus 208: char *methods;
209:
1.28 markus 210: if (!authctxt->valid && authenticated)
211: fatal("INTERNAL ERROR: authenticated invalid user %s",
212: authctxt->user);
1.18 markus 213:
214: /* Special handling for root */
1.96 markus 215: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 216: !auth_root_allowed(method))
1.3 markus 217: authenticated = 0;
218:
1.18 markus 219: /* Log before sending the reply */
1.28 markus 220: auth_log(authctxt, authenticated, method, " ssh2");
221:
1.60 markus 222: if (authctxt->postponed)
223: return;
224:
225: /* XXX todo: check if multiple auth methods are needed */
226: if (authenticated == 1) {
227: /* turn off userauth */
1.81 markus 228: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 229: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
230: packet_send();
231: packet_write_wait();
232: /* now we can break out */
233: authctxt->success = 1;
234: } else {
1.105 dtucker 235: if (authctxt->failures++ > options.max_authtries)
1.60 markus 236: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
237: methods = authmethods_get();
238: packet_start(SSH2_MSG_USERAUTH_FAILURE);
239: packet_put_cstring(methods);
240: packet_put_char(0); /* XXX partial success, unused */
241: packet_send();
242: packet_write_wait();
243: xfree(methods);
244: }
1.1 markus 245: }
246:
1.18 markus 247: #define DELIM ","
248:
1.67 stevesk 249: static char *
1.18 markus 250: authmethods_get(void)
1.1 markus 251: {
1.82 markus 252: Buffer b;
1.18 markus 253: char *list;
1.93 markus 254: int i;
1.1 markus 255:
1.82 markus 256: buffer_init(&b);
1.93 markus 257: for (i = 0; authmethods[i] != NULL; i++) {
258: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 259: continue;
1.93 markus 260: if (authmethods[i]->enabled != NULL &&
261: *(authmethods[i]->enabled) != 0) {
1.82 markus 262: if (buffer_len(&b) > 0)
263: buffer_append(&b, ",", 1);
1.93 markus 264: buffer_append(&b, authmethods[i]->name,
265: strlen(authmethods[i]->name));
1.1 markus 266: }
267: }
1.82 markus 268: buffer_append(&b, "\0", 1);
269: list = xstrdup(buffer_ptr(&b));
270: buffer_free(&b);
1.18 markus 271: return list;
272: }
273:
1.66 itojun 274: static Authmethod *
1.18 markus 275: authmethod_lookup(const char *name)
276: {
1.93 markus 277: int i;
278:
1.18 markus 279: if (name != NULL)
1.93 markus 280: for (i = 0; authmethods[i] != NULL; i++)
281: if (authmethods[i]->enabled != NULL &&
282: *(authmethods[i]->enabled) != 0 &&
283: strcmp(name, authmethods[i]->name) == 0)
284: return authmethods[i];
285: debug2("Unrecognized authentication method name: %s",
286: name ? name : "NULL");
1.18 markus 287: return NULL;
1.1 markus 288: }
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