Annotation of src/usr.bin/ssh/auth2.c, Revision 1.108
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"
26:
1.32 markus 27: #include "ssh2.h"
1.1 markus 28: #include "xmalloc.h"
29: #include "packet.h"
1.32 markus 30: #include "log.h"
1.1 markus 31: #include "servconf.h"
32: #include "compat.h"
33: #include "auth.h"
34: #include "dispatch.h"
1.29 markus 35: #include "pathnames.h"
1.88 provos 36: #include "monitor_wrap.h"
1.1 markus 37:
1.100 markus 38: #ifdef GSSAPI
39: #include "ssh-gss.h"
40: #endif
41:
1.1 markus 42: /* import */
43: extern ServerOptions options;
1.23 markus 44: extern u_char *session_id2;
1.99 markus 45: extern u_int session_id2_len;
1.1 markus 46:
1.93 markus 47: /* methods */
48:
49: extern Authmethod method_none;
50: extern Authmethod method_pubkey;
51: extern Authmethod method_passwd;
52: extern Authmethod method_kbdint;
53: extern Authmethod method_hostbased;
1.100 markus 54: #ifdef GSSAPI
55: extern Authmethod method_gssapi;
56: #endif
1.93 markus 57:
58: Authmethod *authmethods[] = {
59: &method_none,
60: &method_pubkey,
1.100 markus 61: #ifdef GSSAPI
62: &method_gssapi,
63: #endif
1.93 markus 64: &method_passwd,
65: &method_kbdint,
66: &method_hostbased,
67: NULL
1.18 markus 68: };
69:
1.1 markus 70: /* protocol */
71:
1.80 markus 72: static void input_service_request(int, u_int32_t, void *);
73: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 74:
75: /* helper */
1.66 itojun 76: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 77: static char *authmethods_get(void);
1.88 provos 78: int user_key_allowed(struct passwd *, Key *);
1.1 markus 79:
80: /*
1.18 markus 81: * loop until authctxt->success == TRUE
1.1 markus 82: */
83:
1.103 markus 84: void
85: do_authentication2(Authctxt *authctxt)
1.1 markus 86: {
1.71 markus 87: /* challenge-response is implemented via keyboard interactive */
1.57 markus 88: if (options.challenge_response_authentication)
1.34 markus 89: options.kbd_interactive_authentication = 1;
90:
1.81 markus 91: dispatch_init(&dispatch_protocol_error);
1.1 markus 92: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 93: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.1 markus 94: }
95:
1.66 itojun 96: static void
1.80 markus 97: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 98: {
1.18 markus 99: Authctxt *authctxt = ctxt;
1.23 markus 100: u_int len;
1.94 deraadt 101: int acceptit = 0;
1.1 markus 102: char *service = packet_get_string(&len);
1.79 markus 103: packet_check_eom();
1.1 markus 104:
1.18 markus 105: if (authctxt == NULL)
106: fatal("input_service_request: no authctxt");
107:
1.1 markus 108: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 109: if (!authctxt->success) {
1.94 deraadt 110: acceptit = 1;
1.1 markus 111: /* now we can handle user-auth requests */
112: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
113: }
114: }
115: /* XXX all other service requests are denied */
116:
1.94 deraadt 117: if (acceptit) {
1.1 markus 118: packet_start(SSH2_MSG_SERVICE_ACCEPT);
119: packet_put_cstring(service);
120: packet_send();
121: packet_write_wait();
122: } else {
123: debug("bad service request %s", service);
124: packet_disconnect("bad service request %s", service);
125: }
126: xfree(service);
127: }
128:
1.66 itojun 129: static void
1.80 markus 130: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 131: {
1.18 markus 132: Authctxt *authctxt = ctxt;
133: Authmethod *m = NULL;
1.28 markus 134: char *user, *service, *method, *style = NULL;
1.1 markus 135: int authenticated = 0;
136:
1.18 markus 137: if (authctxt == NULL)
138: fatal("input_userauth_request: no authctxt");
1.1 markus 139:
1.18 markus 140: user = packet_get_string(NULL);
141: service = packet_get_string(NULL);
142: method = packet_get_string(NULL);
1.1 markus 143: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 144: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 145:
1.28 markus 146: if ((style = strchr(user, ':')) != NULL)
147: *style++ = 0;
148:
1.36 stevesk 149: if (authctxt->attempt++ == 0) {
1.18 markus 150: /* setup auth context */
1.89 markus 151: authctxt->pw = PRIVSEP(getpwnamallow(user));
152: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 153: authctxt->valid = 1;
154: debug2("input_userauth_request: setting up authctxt for %s", user);
155: } else {
1.107 markus 156: logit("input_userauth_request: invalid user %s", user);
1.102 markus 157: authctxt->pw = fakepw();
1.18 markus 158: }
1.106 djm 159: setproctitle("%s%s", authctxt->valid ? user : "unknown",
1.88 provos 160: use_privsep ? " [net]" : "");
1.18 markus 161: authctxt->user = xstrdup(user);
162: authctxt->service = xstrdup(service);
1.62 markus 163: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 164: if (use_privsep)
165: mm_inform_authserv(service, style);
1.62 markus 166: } else if (strcmp(user, authctxt->user) != 0 ||
167: strcmp(service, authctxt->service) != 0) {
168: packet_disconnect("Change of username or service not allowed: "
169: "(%s,%s) -> (%s,%s)",
170: authctxt->user, authctxt->service, user, service);
1.1 markus 171: }
1.28 markus 172: /* reset state */
1.75 markus 173: auth2_challenge_stop(authctxt);
1.100 markus 174:
175: #ifdef GSSAPI
176: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
177: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
178: #endif
179:
1.28 markus 180: authctxt->postponed = 0;
1.18 markus 181:
1.28 markus 182: /* try to authenticate user */
1.18 markus 183: m = authmethod_lookup(method);
184: if (m != NULL) {
185: debug2("input_userauth_request: try method %s", method);
186: authenticated = m->userauth(authctxt);
187: }
1.49 markus 188: userauth_finish(authctxt, authenticated, method);
189:
190: xfree(service);
191: xfree(user);
192: xfree(method);
193: }
194:
195: void
196: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
197: {
1.60 markus 198: char *methods;
199:
1.28 markus 200: if (!authctxt->valid && authenticated)
201: fatal("INTERNAL ERROR: authenticated invalid user %s",
202: authctxt->user);
1.18 markus 203:
204: /* Special handling for root */
1.96 markus 205: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 206: !auth_root_allowed(method))
1.3 markus 207: authenticated = 0;
208:
1.18 markus 209: /* Log before sending the reply */
1.28 markus 210: auth_log(authctxt, authenticated, method, " ssh2");
211:
1.60 markus 212: if (authctxt->postponed)
213: return;
214:
215: /* XXX todo: check if multiple auth methods are needed */
216: if (authenticated == 1) {
217: /* turn off userauth */
1.81 markus 218: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 219: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
220: packet_send();
221: packet_write_wait();
222: /* now we can break out */
223: authctxt->success = 1;
224: } else {
1.105 dtucker 225: if (authctxt->failures++ > options.max_authtries)
1.60 markus 226: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
227: methods = authmethods_get();
228: packet_start(SSH2_MSG_USERAUTH_FAILURE);
229: packet_put_cstring(methods);
230: packet_put_char(0); /* XXX partial success, unused */
231: packet_send();
232: packet_write_wait();
233: xfree(methods);
234: }
1.1 markus 235: }
236:
1.18 markus 237: #define DELIM ","
238:
1.67 stevesk 239: static char *
1.18 markus 240: authmethods_get(void)
1.1 markus 241: {
1.82 markus 242: Buffer b;
1.18 markus 243: char *list;
1.93 markus 244: int i;
1.1 markus 245:
1.82 markus 246: buffer_init(&b);
1.93 markus 247: for (i = 0; authmethods[i] != NULL; i++) {
248: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 249: continue;
1.93 markus 250: if (authmethods[i]->enabled != NULL &&
251: *(authmethods[i]->enabled) != 0) {
1.82 markus 252: if (buffer_len(&b) > 0)
253: buffer_append(&b, ",", 1);
1.93 markus 254: buffer_append(&b, authmethods[i]->name,
255: strlen(authmethods[i]->name));
1.1 markus 256: }
257: }
1.82 markus 258: buffer_append(&b, "\0", 1);
259: list = xstrdup(buffer_ptr(&b));
260: buffer_free(&b);
1.18 markus 261: return list;
262: }
263:
1.66 itojun 264: static Authmethod *
1.18 markus 265: authmethod_lookup(const char *name)
266: {
1.93 markus 267: int i;
268:
1.18 markus 269: if (name != NULL)
1.93 markus 270: for (i = 0; authmethods[i] != NULL; i++)
271: if (authmethods[i]->enabled != NULL &&
272: *(authmethods[i]->enabled) != 0 &&
273: strcmp(name, authmethods[i]->name) == 0)
274: return authmethods[i];
275: debug2("Unrecognized authentication method name: %s",
276: name ? name : "NULL");
1.18 markus 277: return NULL;
1.1 markus 278: }
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