Annotation of src/usr.bin/ssh/auth2.c, Revision 1.99
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"
1.99 ! markus 26: RCSID("$OpenBSD: auth2.c,v 1.98 2003/05/14 02:15:47 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:
39: /* import */
40: extern ServerOptions options;
1.23 markus 41: extern u_char *session_id2;
1.99 ! markus 42: extern u_int session_id2_len;
1.1 markus 43:
1.88 provos 44: Authctxt *x_authctxt = NULL;
1.18 markus 45:
1.93 markus 46: /* methods */
47:
48: extern Authmethod method_none;
49: extern Authmethod method_pubkey;
50: extern Authmethod method_passwd;
51: extern Authmethod method_kbdint;
52: extern Authmethod method_hostbased;
1.98 markus 53: #ifdef KRB5
54: extern Authmethod method_kerberos;
55: #endif
1.93 markus 56:
57: Authmethod *authmethods[] = {
58: &method_none,
59: &method_pubkey,
60: &method_passwd,
61: &method_kbdint,
62: &method_hostbased,
1.98 markus 63: #ifdef KRB5
64: &method_kerberos,
65: #endif
1.93 markus 66: NULL
1.18 markus 67: };
68:
1.1 markus 69: /* protocol */
70:
1.80 markus 71: static void input_service_request(int, u_int32_t, void *);
72: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 73:
74: /* helper */
1.66 itojun 75: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 76: static char *authmethods_get(void);
1.88 provos 77: int user_key_allowed(struct passwd *, Key *);
78: int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
1.1 markus 79:
80: /*
1.18 markus 81: * loop until authctxt->success == TRUE
1.1 markus 82: */
83:
1.87 provos 84: Authctxt *
1.74 itojun 85: do_authentication2(void)
1.1 markus 86: {
1.28 markus 87: Authctxt *authctxt = authctxt_new();
88:
1.18 markus 89: x_authctxt = authctxt; /*XXX*/
90:
1.71 markus 91: /* challenge-response is implemented via keyboard interactive */
1.57 markus 92: if (options.challenge_response_authentication)
1.34 markus 93: options.kbd_interactive_authentication = 1;
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);
1.87 provos 98:
99: return (authctxt);
1.1 markus 100: }
101:
1.66 itojun 102: static void
1.80 markus 103: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 104: {
1.18 markus 105: Authctxt *authctxt = ctxt;
1.23 markus 106: u_int len;
1.94 deraadt 107: int acceptit = 0;
1.1 markus 108: char *service = packet_get_string(&len);
1.79 markus 109: packet_check_eom();
1.1 markus 110:
1.18 markus 111: if (authctxt == NULL)
112: fatal("input_service_request: no authctxt");
113:
1.1 markus 114: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 115: if (!authctxt->success) {
1.94 deraadt 116: acceptit = 1;
1.1 markus 117: /* now we can handle user-auth requests */
118: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
119: }
120: }
121: /* XXX all other service requests are denied */
122:
1.94 deraadt 123: if (acceptit) {
1.1 markus 124: packet_start(SSH2_MSG_SERVICE_ACCEPT);
125: packet_put_cstring(service);
126: packet_send();
127: packet_write_wait();
128: } else {
129: debug("bad service request %s", service);
130: packet_disconnect("bad service request %s", service);
131: }
132: xfree(service);
133: }
134:
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 {
1.97 itojun 162: logit("input_userauth_request: illegal user %s", user);
1.18 markus 163: }
1.89 markus 164: setproctitle("%s%s", authctxt->pw ? user : "unknown",
1.88 provos 165: use_privsep ? " [net]" : "");
1.18 markus 166: authctxt->user = xstrdup(user);
167: authctxt->service = xstrdup(service);
1.62 markus 168: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 169: if (use_privsep)
170: mm_inform_authserv(service, style);
1.62 markus 171: } else if (strcmp(user, authctxt->user) != 0 ||
172: strcmp(service, authctxt->service) != 0) {
173: packet_disconnect("Change of username or service not allowed: "
174: "(%s,%s) -> (%s,%s)",
175: authctxt->user, authctxt->service, user, service);
1.1 markus 176: }
1.28 markus 177: /* reset state */
1.75 markus 178: auth2_challenge_stop(authctxt);
1.28 markus 179: authctxt->postponed = 0;
1.18 markus 180:
1.28 markus 181: /* try to authenticate user */
1.18 markus 182: m = authmethod_lookup(method);
183: if (m != NULL) {
184: debug2("input_userauth_request: try method %s", method);
185: authenticated = m->userauth(authctxt);
186: }
1.49 markus 187: userauth_finish(authctxt, authenticated, method);
188:
189: xfree(service);
190: xfree(user);
191: xfree(method);
192: }
193:
194: void
195: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
196: {
1.60 markus 197: char *methods;
198:
1.28 markus 199: if (!authctxt->valid && authenticated)
200: fatal("INTERNAL ERROR: authenticated invalid user %s",
201: authctxt->user);
1.18 markus 202:
203: /* Special handling for root */
1.96 markus 204: if (authenticated && authctxt->pw->pw_uid == 0 &&
1.41 markus 205: !auth_root_allowed(method))
1.3 markus 206: authenticated = 0;
207:
1.18 markus 208: /* Log before sending the reply */
1.28 markus 209: auth_log(authctxt, authenticated, method, " ssh2");
210:
1.60 markus 211: if (authctxt->postponed)
212: return;
213:
214: /* XXX todo: check if multiple auth methods are needed */
215: if (authenticated == 1) {
216: /* turn off userauth */
1.81 markus 217: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 218: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
219: packet_send();
220: packet_write_wait();
221: /* now we can break out */
222: authctxt->success = 1;
223: } else {
224: if (authctxt->failures++ > AUTH_FAIL_MAX)
225: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
226: methods = authmethods_get();
227: packet_start(SSH2_MSG_USERAUTH_FAILURE);
228: packet_put_cstring(methods);
229: packet_put_char(0); /* XXX partial success, unused */
230: packet_send();
231: packet_write_wait();
232: xfree(methods);
233: }
1.18 markus 234: }
235:
236: /* get current user */
1.1 markus 237:
238: struct passwd*
239: auth_get_user(void)
240: {
1.18 markus 241: return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
1.1 markus 242: }
243:
1.18 markus 244: #define DELIM ","
245:
1.67 stevesk 246: static char *
1.18 markus 247: authmethods_get(void)
1.1 markus 248: {
1.82 markus 249: Buffer b;
1.18 markus 250: char *list;
1.93 markus 251: int i;
1.1 markus 252:
1.82 markus 253: buffer_init(&b);
1.93 markus 254: for (i = 0; authmethods[i] != NULL; i++) {
255: if (strcmp(authmethods[i]->name, "none") == 0)
1.18 markus 256: continue;
1.93 markus 257: if (authmethods[i]->enabled != NULL &&
258: *(authmethods[i]->enabled) != 0) {
1.82 markus 259: if (buffer_len(&b) > 0)
260: buffer_append(&b, ",", 1);
1.93 markus 261: buffer_append(&b, authmethods[i]->name,
262: strlen(authmethods[i]->name));
1.1 markus 263: }
264: }
1.82 markus 265: buffer_append(&b, "\0", 1);
266: list = xstrdup(buffer_ptr(&b));
267: buffer_free(&b);
1.18 markus 268: return list;
269: }
270:
1.66 itojun 271: static Authmethod *
1.18 markus 272: authmethod_lookup(const char *name)
273: {
1.93 markus 274: int i;
275:
1.18 markus 276: if (name != NULL)
1.93 markus 277: for (i = 0; authmethods[i] != NULL; i++)
278: if (authmethods[i]->enabled != NULL &&
279: *(authmethods[i]->enabled) != 0 &&
280: strcmp(name, authmethods[i]->name) == 0)
281: return authmethods[i];
282: debug2("Unrecognized authentication method name: %s",
283: name ? name : "NULL");
1.18 markus 284: return NULL;
1.1 markus 285: }
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