Annotation of src/usr.bin/ssh/auth2.c, Revision 1.107
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"
1.107 ! markus 26: RCSID("$OpenBSD: auth2.c,v 1.106 2004/07/21 10:33:31 djm 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 *);
1.1 markus 80:
81: /*
1.18 markus 82: * loop until authctxt->success == TRUE
1.1 markus 83: */
84:
1.103 markus 85: void
86: do_authentication2(Authctxt *authctxt)
1.1 markus 87: {
1.71 markus 88: /* challenge-response is implemented via keyboard interactive */
1.57 markus 89: if (options.challenge_response_authentication)
1.34 markus 90: options.kbd_interactive_authentication = 1;
91:
1.81 markus 92: dispatch_init(&dispatch_protocol_error);
1.1 markus 93: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 94: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 95: }
96:
1.66 itojun 97: static void
1.80 markus 98: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 99: {
1.18 markus 100: Authctxt *authctxt = ctxt;
1.23 markus 101: u_int len;
1.94 deraadt 102: int acceptit = 0;
1.1 markus 103: char *service = packet_get_string(&len);
1.79 markus 104: packet_check_eom();
1.1 markus 105:
1.18 markus 106: if (authctxt == NULL)
107: fatal("input_service_request: no authctxt");
108:
1.1 markus 109: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 110: if (!authctxt->success) {
1.94 deraadt 111: acceptit = 1;
1.1 markus 112: /* now we can handle user-auth requests */
113: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
114: }
115: }
116: /* XXX all other service requests are denied */
117:
1.94 deraadt 118: if (acceptit) {
1.1 markus 119: packet_start(SSH2_MSG_SERVICE_ACCEPT);
120: packet_put_cstring(service);
121: packet_send();
122: packet_write_wait();
123: } else {
124: debug("bad service request %s", service);
125: packet_disconnect("bad service request %s", service);
126: }
127: xfree(service);
128: }
129:
1.66 itojun 130: static void
1.80 markus 131: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 132: {
1.18 markus 133: Authctxt *authctxt = ctxt;
134: Authmethod *m = NULL;
1.28 markus 135: char *user, *service, *method, *style = NULL;
1.1 markus 136: int authenticated = 0;
137:
1.18 markus 138: if (authctxt == NULL)
139: fatal("input_userauth_request: no authctxt");
1.1 markus 140:
1.18 markus 141: user = packet_get_string(NULL);
142: service = packet_get_string(NULL);
143: method = packet_get_string(NULL);
1.1 markus 144: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 145: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 146:
1.28 markus 147: if ((style = strchr(user, ':')) != NULL)
148: *style++ = 0;
149:
1.36 stevesk 150: if (authctxt->attempt++ == 0) {
1.18 markus 151: /* setup auth context */
1.89 markus 152: authctxt->pw = PRIVSEP(getpwnamallow(user));
153: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 154: authctxt->valid = 1;
155: debug2("input_userauth_request: setting up authctxt for %s", user);
156: } else {
1.107 ! markus 157: logit("input_userauth_request: invalid user %s", user);
1.102 markus 158: authctxt->pw = fakepw();
1.18 markus 159: }
1.106 djm 160: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 161: use_privsep ? " [net]" : "");
1.18 markus 162: authctxt->user = xstrdup(user);
163: authctxt->service = xstrdup(service);
1.62 markus 164: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 165: if (use_privsep)
166: mm_inform_authserv(service, style);
1.62 markus 167: } else if (strcmp(user, authctxt->user) != 0 ||
168: strcmp(service, authctxt->service) != 0) {
169: packet_disconnect("Change of username or service not allowed: "
170: "(%s,%s) -> (%s,%s)",
171: authctxt->user, authctxt->service, user, service);
1.1 markus 172: }
1.28 markus 173: /* reset state */
1.75 markus 174: auth2_challenge_stop(authctxt);
1.100 markus 175:
176: #ifdef GSSAPI
177: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
178: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
179: #endif
180:
1.28 markus 181: authctxt->postponed = 0;
1.18 markus 182:
1.28 markus 183: /* try to authenticate user */
1.18 markus 184: m = authmethod_lookup(method);
185: if (m != NULL) {
186: debug2("input_userauth_request: try method %s", method);
187: authenticated = m->userauth(authctxt);
188: }
1.49 markus 189: userauth_finish(authctxt, authenticated, method);
190:
191: xfree(service);
192: xfree(user);
193: xfree(method);
194: }
195:
196: void
197: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
198: {
1.60 markus 199: char *methods;
200:
1.28 markus 201: if (!authctxt->valid && authenticated)
202: fatal("INTERNAL ERROR: authenticated invalid user %s",
203: authctxt->user);
1.18 markus 204:
205: /* Special handling for root */
1.96 markus 206: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 207: !auth_root_allowed(method))
1.3 markus 208: authenticated = 0;
209:
1.18 markus 210: /* Log before sending the reply */
1.28 markus 211: auth_log(authctxt, authenticated, method, " ssh2");
212:
1.60 markus 213: if (authctxt->postponed)
214: return;
215:
216: /* XXX todo: check if multiple auth methods are needed */
217: if (authenticated == 1) {
218: /* turn off userauth */
1.81 markus 219: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 220: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
221: packet_send();
222: packet_write_wait();
223: /* now we can break out */
224: authctxt->success = 1;
225: } else {
1.105 dtucker 226: if (authctxt->failures++ > options.max_authtries)
1.60 markus 227: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
228: methods = authmethods_get();
229: packet_start(SSH2_MSG_USERAUTH_FAILURE);
230: packet_put_cstring(methods);
231: packet_put_char(0); /* XXX partial success, unused */
232: packet_send();
233: packet_write_wait();
234: xfree(methods);
235: }
1.1 markus 236: }
237:
1.18 markus 238: #define DELIM ","
239:
1.67 stevesk 240: static char *
1.18 markus 241: authmethods_get(void)
1.1 markus 242: {
1.82 markus 243: Buffer b;
1.18 markus 244: char *list;
1.93 markus 245: int i;
1.1 markus 246:
1.82 markus 247: buffer_init(&b);
1.93 markus 248: for (i = 0; authmethods[i] != NULL; i++) {
249: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 250: continue;
1.93 markus 251: if (authmethods[i]->enabled != NULL &&
252: *(authmethods[i]->enabled) != 0) {
1.82 markus 253: if (buffer_len(&b) > 0)
254: buffer_append(&b, ",", 1);
1.93 markus 255: buffer_append(&b, authmethods[i]->name,
256: strlen(authmethods[i]->name));
1.1 markus 257: }
258: }
1.82 markus 259: buffer_append(&b, "\0", 1);
260: list = xstrdup(buffer_ptr(&b));
261: buffer_free(&b);
1.18 markus 262: return list;
263: }
264:
1.66 itojun 265: static Authmethod *
1.18 markus 266: authmethod_lookup(const char *name)
267: {
1.93 markus 268: int i;
269:
1.18 markus 270: if (name != NULL)
1.93 markus 271: for (i = 0; authmethods[i] != NULL; i++)
272: if (authmethods[i]->enabled != NULL &&
273: *(authmethods[i]->enabled) != 0 &&
274: strcmp(name, authmethods[i]->name) == 0)
275: return authmethods[i];
276: debug2("Unrecognized authentication method name: %s",
277: name ? name : "NULL");
1.18 markus 278: return NULL;
1.1 markus 279: }
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