Annotation of src/usr.bin/ssh/auth2.c, Revision 1.94
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"
1.94 ! deraadt 26: RCSID("$OpenBSD: auth2.c,v 1.93 2002/05/31 11:35:15 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;
1.1 markus 42: extern int session_id2_len;
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;
53:
54: Authmethod *authmethods[] = {
55: &method_none,
56: &method_pubkey,
57: &method_passwd,
58: &method_kbdint,
59: &method_hostbased,
60: NULL
1.18 markus 61: };
62:
1.1 markus 63: /* protocol */
64:
1.80 markus 65: static void input_service_request(int, u_int32_t, void *);
66: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 67:
68: /* helper */
1.66 itojun 69: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 70: static char *authmethods_get(void);
1.88 provos 71: int user_key_allowed(struct passwd *, Key *);
72: int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
1.1 markus 73:
74: /*
1.18 markus 75: * loop until authctxt->success == TRUE
1.1 markus 76: */
77:
1.87 provos 78: Authctxt *
1.74 itojun 79: do_authentication2(void)
1.1 markus 80: {
1.28 markus 81: Authctxt *authctxt = authctxt_new();
82:
1.18 markus 83: x_authctxt = authctxt; /*XXX*/
84:
1.71 markus 85: /* challenge-response is implemented via keyboard interactive */
1.57 markus 86: if (options.challenge_response_authentication)
1.34 markus 87: options.kbd_interactive_authentication = 1;
88:
1.81 markus 89: dispatch_init(&dispatch_protocol_error);
1.1 markus 90: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 91: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.87 provos 92:
93: return (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 {
156: log("input_userauth_request: illegal user %s", user);
157: }
1.89 markus 158: setproctitle("%s%s", authctxt->pw ? user : "unknown",
1.88 provos 159: use_privsep ? " [net]" : "");
1.18 markus 160: authctxt->user = xstrdup(user);
161: authctxt->service = xstrdup(service);
1.62 markus 162: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 163: if (use_privsep)
164: mm_inform_authserv(service, style);
1.62 markus 165: } else if (strcmp(user, authctxt->user) != 0 ||
166: strcmp(service, authctxt->service) != 0) {
167: packet_disconnect("Change of username or service not allowed: "
168: "(%s,%s) -> (%s,%s)",
169: authctxt->user, authctxt->service, user, service);
1.1 markus 170: }
1.28 markus 171: /* reset state */
1.75 markus 172: auth2_challenge_stop(authctxt);
1.28 markus 173: authctxt->postponed = 0;
1.18 markus 174:
1.28 markus 175: /* try to authenticate user */
1.18 markus 176: m = authmethod_lookup(method);
177: if (m != NULL) {
178: debug2("input_userauth_request: try method %s", method);
179: authenticated = m->userauth(authctxt);
180: }
1.49 markus 181: userauth_finish(authctxt, authenticated, method);
182:
183: xfree(service);
184: xfree(user);
185: xfree(method);
186: }
187:
188: void
189: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
190: {
1.60 markus 191: char *methods;
192:
1.28 markus 193: if (!authctxt->valid && authenticated)
194: fatal("INTERNAL ERROR: authenticated invalid user %s",
195: authctxt->user);
1.18 markus 196:
197: /* Special handling for root */
1.41 markus 198: if (authenticated && authctxt->pw->pw_uid == 0 &&
199: !auth_root_allowed(method))
1.3 markus 200: authenticated = 0;
201:
1.18 markus 202: /* Log before sending the reply */
1.28 markus 203: auth_log(authctxt, authenticated, method, " ssh2");
204:
1.60 markus 205: if (authctxt->postponed)
206: return;
207:
208: /* XXX todo: check if multiple auth methods are needed */
209: if (authenticated == 1) {
210: /* turn off userauth */
1.81 markus 211: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 212: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
213: packet_send();
214: packet_write_wait();
215: /* now we can break out */
216: authctxt->success = 1;
217: } else {
218: if (authctxt->failures++ > AUTH_FAIL_MAX)
219: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
220: methods = authmethods_get();
221: packet_start(SSH2_MSG_USERAUTH_FAILURE);
222: packet_put_cstring(methods);
223: packet_put_char(0); /* XXX partial success, unused */
224: packet_send();
225: packet_write_wait();
226: xfree(methods);
227: }
1.18 markus 228: }
229:
230: /* get current user */
1.1 markus 231:
232: struct passwd*
233: auth_get_user(void)
234: {
1.18 markus 235: return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
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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