Annotation of src/usr.bin/ssh/auth2.c, Revision 1.92
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"
1.92 ! markus 26: RCSID("$OpenBSD: auth2.c,v 1.91 2002/05/13 02:37:39 itojun 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: static int one = 1;
46:
47: typedef struct Authmethod Authmethod;
48: struct Authmethod {
49: char *name;
50: int (*userauth)(Authctxt *authctxt);
51: int *enabled;
52: };
53:
1.1 markus 54: /* protocol */
55:
1.80 markus 56: static void input_service_request(int, u_int32_t, void *);
57: static void input_userauth_request(int, u_int32_t, void *);
1.1 markus 58:
59: /* helper */
1.66 itojun 60: static Authmethod *authmethod_lookup(const char *);
1.67 stevesk 61: static char *authmethods_get(void);
1.88 provos 62: int user_key_allowed(struct passwd *, Key *);
63: int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
1.1 markus 64:
1.18 markus 65: /* auth */
66:
67: Authmethod authmethods[] = {
68: {"none",
69: userauth_none,
70: &one},
71: {"publickey",
72: userauth_pubkey,
1.21 markus 73: &options.pubkey_authentication},
1.40 markus 74: {"password",
75: userauth_passwd,
76: &options.password_authentication},
1.18 markus 77: {"keyboard-interactive",
78: userauth_kbdint,
79: &options.kbd_interactive_authentication},
1.52 markus 80: {"hostbased",
81: userauth_hostbased,
82: &options.hostbased_authentication},
1.18 markus 83: {NULL, NULL, NULL}
1.1 markus 84: };
85:
86: /*
1.18 markus 87: * loop until authctxt->success == TRUE
1.1 markus 88: */
89:
1.87 provos 90: Authctxt *
1.74 itojun 91: do_authentication2(void)
1.1 markus 92: {
1.28 markus 93: Authctxt *authctxt = authctxt_new();
94:
1.18 markus 95: x_authctxt = authctxt; /*XXX*/
96:
1.71 markus 97: /* challenge-response is implemented via keyboard interactive */
1.57 markus 98: if (options.challenge_response_authentication)
1.34 markus 99: options.kbd_interactive_authentication = 1;
100:
1.81 markus 101: dispatch_init(&dispatch_protocol_error);
1.1 markus 102: dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
1.18 markus 103: dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1.87 provos 104:
105: return (authctxt);
1.1 markus 106: }
107:
1.66 itojun 108: static void
1.80 markus 109: input_service_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 110: {
1.18 markus 111: Authctxt *authctxt = ctxt;
1.23 markus 112: u_int len;
1.1 markus 113: int accept = 0;
114: char *service = packet_get_string(&len);
1.79 markus 115: packet_check_eom();
1.1 markus 116:
1.18 markus 117: if (authctxt == NULL)
118: fatal("input_service_request: no authctxt");
119:
1.1 markus 120: if (strcmp(service, "ssh-userauth") == 0) {
1.18 markus 121: if (!authctxt->success) {
1.1 markus 122: accept = 1;
123: /* now we can handle user-auth requests */
124: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
125: }
126: }
127: /* XXX all other service requests are denied */
128:
129: if (accept) {
130: packet_start(SSH2_MSG_SERVICE_ACCEPT);
131: packet_put_cstring(service);
132: packet_send();
133: packet_write_wait();
134: } else {
135: debug("bad service request %s", service);
136: packet_disconnect("bad service request %s", service);
137: }
138: xfree(service);
139: }
140:
1.66 itojun 141: static void
1.80 markus 142: input_userauth_request(int type, u_int32_t seq, void *ctxt)
1.1 markus 143: {
1.18 markus 144: Authctxt *authctxt = ctxt;
145: Authmethod *m = NULL;
1.28 markus 146: char *user, *service, *method, *style = NULL;
1.1 markus 147: int authenticated = 0;
148:
1.18 markus 149: if (authctxt == NULL)
150: fatal("input_userauth_request: no authctxt");
1.1 markus 151:
1.18 markus 152: user = packet_get_string(NULL);
153: service = packet_get_string(NULL);
154: method = packet_get_string(NULL);
1.1 markus 155: debug("userauth-request for user %s service %s method %s", user, service, method);
1.24 markus 156: debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
1.1 markus 157:
1.28 markus 158: if ((style = strchr(user, ':')) != NULL)
159: *style++ = 0;
160:
1.36 stevesk 161: if (authctxt->attempt++ == 0) {
1.18 markus 162: /* setup auth context */
1.89 markus 163: authctxt->pw = PRIVSEP(getpwnamallow(user));
164: if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
1.18 markus 165: authctxt->valid = 1;
166: debug2("input_userauth_request: setting up authctxt for %s", user);
167: } else {
168: log("input_userauth_request: illegal user %s", user);
169: }
1.89 markus 170: setproctitle("%s%s", authctxt->pw ? user : "unknown",
1.88 provos 171: use_privsep ? " [net]" : "");
1.18 markus 172: authctxt->user = xstrdup(user);
173: authctxt->service = xstrdup(service);
1.62 markus 174: authctxt->style = style ? xstrdup(style) : NULL;
1.88 provos 175: if (use_privsep)
176: mm_inform_authserv(service, style);
1.62 markus 177: } else if (strcmp(user, authctxt->user) != 0 ||
178: strcmp(service, authctxt->service) != 0) {
179: packet_disconnect("Change of username or service not allowed: "
180: "(%s,%s) -> (%s,%s)",
181: authctxt->user, authctxt->service, user, service);
1.1 markus 182: }
1.28 markus 183: /* reset state */
1.75 markus 184: auth2_challenge_stop(authctxt);
1.28 markus 185: authctxt->postponed = 0;
1.18 markus 186:
1.28 markus 187: /* try to authenticate user */
1.18 markus 188: m = authmethod_lookup(method);
189: if (m != NULL) {
190: debug2("input_userauth_request: try method %s", method);
191: authenticated = m->userauth(authctxt);
192: }
1.49 markus 193: userauth_finish(authctxt, authenticated, method);
194:
195: xfree(service);
196: xfree(user);
197: xfree(method);
198: }
199:
200: void
201: userauth_finish(Authctxt *authctxt, int authenticated, char *method)
202: {
1.60 markus 203: char *methods;
204:
1.28 markus 205: if (!authctxt->valid && authenticated)
206: fatal("INTERNAL ERROR: authenticated invalid user %s",
207: authctxt->user);
1.18 markus 208:
209: /* Special handling for root */
1.41 markus 210: if (authenticated && authctxt->pw->pw_uid == 0 &&
211: !auth_root_allowed(method))
1.3 markus 212: authenticated = 0;
213:
1.18 markus 214: /* Log before sending the reply */
1.28 markus 215: auth_log(authctxt, authenticated, method, " ssh2");
216:
1.60 markus 217: if (authctxt->postponed)
218: return;
219:
220: /* XXX todo: check if multiple auth methods are needed */
221: if (authenticated == 1) {
222: /* turn off userauth */
1.81 markus 223: dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
1.60 markus 224: packet_start(SSH2_MSG_USERAUTH_SUCCESS);
225: packet_send();
226: packet_write_wait();
227: /* now we can break out */
228: authctxt->success = 1;
229: } else {
230: if (authctxt->failures++ > AUTH_FAIL_MAX)
231: packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
232: methods = authmethods_get();
233: packet_start(SSH2_MSG_USERAUTH_FAILURE);
234: packet_put_cstring(methods);
235: packet_put_char(0); /* XXX partial success, unused */
236: packet_send();
237: packet_write_wait();
238: xfree(methods);
239: }
1.18 markus 240: }
241:
242: /* get current user */
1.1 markus 243:
244: struct passwd*
245: auth_get_user(void)
246: {
1.18 markus 247: return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
1.1 markus 248: }
249:
1.18 markus 250: #define DELIM ","
251:
1.67 stevesk 252: static char *
1.18 markus 253: authmethods_get(void)
1.1 markus 254: {
1.18 markus 255: Authmethod *method = NULL;
1.82 markus 256: Buffer b;
1.18 markus 257: char *list;
1.1 markus 258:
1.82 markus 259: buffer_init(&b);
1.18 markus 260: for (method = authmethods; method->name != NULL; method++) {
261: if (strcmp(method->name, "none") == 0)
262: continue;
263: if (method->enabled != NULL && *(method->enabled) != 0) {
1.82 markus 264: if (buffer_len(&b) > 0)
265: buffer_append(&b, ",", 1);
266: buffer_append(&b, method->name, strlen(method->name));
1.1 markus 267: }
268: }
1.82 markus 269: buffer_append(&b, "\0", 1);
270: list = xstrdup(buffer_ptr(&b));
271: buffer_free(&b);
1.18 markus 272: return list;
273: }
274:
1.66 itojun 275: static Authmethod *
1.18 markus 276: authmethod_lookup(const char *name)
277: {
278: Authmethod *method = NULL;
279: if (name != NULL)
280: for (method = authmethods; method->name != NULL; method++)
281: if (method->enabled != NULL &&
282: *(method->enabled) != 0 &&
283: strcmp(name, method->name) == 0)
284: return method;
285: debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
286: return NULL;
1.1 markus 287: }
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