1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1995
5 * Bill Paul <[email protected]>. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by Bill Paul.
18 * 4. Neither the name of the author nor the names of any co-contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 */
35
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include <stdlib.h>
40 #include <rpc/rpc.h>
41 #include <rpcsvc/yp.h>
42 #include <rpcsvc/yppasswd.h>
43 #include <rpcsvc/ypxfrd.h>
44 #include <sys/types.h>
45 #include <limits.h>
46 #include <db.h>
47 #include <sys/socket.h>
48 #include <netinet/in.h>
49 #include <arpa/inet.h>
50 #include <sys/stat.h>
51 #include <sys/fcntl.h>
52 #include <paths.h>
53 #include <errno.h>
54 #include <sys/param.h>
55 #include "yp_extern.h"
56 #ifdef TCP_WRAPPER
57 #include "tcpd.h"
58 #endif
59
60 extern int debug;
61
62 static const char *yp_procs[] = {
63 /* NIS v1 */
64 "ypoldproc_null",
65 "ypoldproc_domain",
66 "ypoldproc_domain_nonack",
67 "ypoldproc_match",
68 "ypoldproc_first",
69 "ypoldproc_next",
70 "ypoldproc_poll",
71 "ypoldproc_push",
72 "ypoldproc_get",
73 "badproc1", /* placeholder */
74 "badproc2", /* placeholder */
75 "badproc3", /* placeholder */
76
77 /* NIS v2 */
78 "ypproc_null",
79 "ypproc_domain",
80 "ypproc_domain_nonack",
81 "ypproc_match",
82 "ypproc_first",
83 "ypproc_next",
84 "ypproc_xfr",
85 "ypproc_clear",
86 "ypproc_all",
87 "ypproc_master",
88 "ypproc_order",
89 "ypproc_maplist"
90 };
91
92 struct securenet {
93 struct in_addr net;
94 struct in_addr mask;
95 struct securenet *next;
96 };
97
98 static struct securenet *securenets;
99
100 #define LINEBUFSZ 1024
101
102 #ifdef TCP_WRAPPER
103 int hosts_ctl(char *, char *, char *, char *);
104 #endif
105
106 /*
107 * Read /var/yp/securenets file and initialize the securenets
108 * list. If the file doesn't exist, we set up a dummy entry that
109 * allows all hosts to connect.
110 */
111 void
load_securenets(void)112 load_securenets(void)
113 {
114 FILE *fp;
115 char path[MAXPATHLEN + 2];
116 char linebuf[1024 + 2];
117 struct securenet *tmp;
118
119 /*
120 * If securenets is not NULL, we are being called to reload
121 * the list; free the existing list before re-reading the
122 * securenets file.
123 */
124 while (securenets) {
125 tmp = securenets->next;
126 free(securenets);
127 securenets = tmp;
128 }
129
130 snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);
131
132 if ((fp = fopen(path, "r")) == NULL) {
133 if (errno == ENOENT) {
134 securenets = malloc(sizeof(struct securenet));
135 securenets->net.s_addr = INADDR_ANY;
136 securenets->mask.s_addr = INADDR_ANY;
137 securenets->next = NULL;
138 return;
139 } else {
140 yp_error("fopen(%s) failed: %s", path, strerror(errno));
141 exit(1);
142 }
143 }
144
145 securenets = NULL;
146
147 while (fgets(linebuf, LINEBUFSZ, fp)) {
148 char addr1[20], addr2[20];
149
150 if ((linebuf[0] == '#')
151 || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
152 continue;
153 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
154 yp_error("badly formatted securenets entry: %s",
155 linebuf);
156 continue;
157 }
158
159 tmp = malloc(sizeof(struct securenet));
160
161 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
162 yp_error("badly formatted securenets entry: %s", addr1);
163 free(tmp);
164 continue;
165 }
166
167 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
168 yp_error("badly formatted securenets entry: %s", addr2);
169 free(tmp);
170 continue;
171 }
172
173 tmp->next = securenets;
174 securenets = tmp;
175 }
176
177 fclose(fp);
178
179 }
180
181 /*
182 * Access control functions.
183 *
184 * yp_access() checks the mapname and client host address and watches for
185 * the following things:
186 *
187 * - If the client is referencing one of the master.passwd.* or shadow.* maps,
188 * it must be using a privileged port to make its RPC to us. If it is, then
189 * we can assume that the caller is root and allow the RPC to succeed. If it
190 * isn't access is denied.
191 *
192 * - The client's IP address is checked against the securenets rules.
193 * There are two kinds of securenets support: the built-in support,
194 * which is very simple and depends on the presence of a
195 * /var/yp/securenets file, and tcp-wrapper support, which requires
196 * Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
197 * package does not ship with FreeBSD, we use the built-in support
198 * by default. Users can recompile the server with the tcp-wrapper library
199 * if they already have it installed and want to use hosts.allow and
200 * hosts.deny to control access instead of having a separate securenets
201 * file.)
202 *
203 * If no /var/yp/securenets file is present, the host access checks
204 * are bypassed and all hosts are allowed to connect.
205 *
206 * The yp_validdomain() function checks the domain specified by the caller
207 * to make sure it's actually served by this server. This is more a sanity
208 * check than an a security check, but this seems to be the best place for
209 * it.
210 */
211
212 #ifdef DB_CACHE
213 int
yp_access(const char * map,const char * domain,const struct svc_req * rqstp)214 yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
215 #else
216 int
217 yp_access(const char *map, const struct svc_req *rqstp)
218 #endif
219 {
220 struct sockaddr_in *rqhost;
221 int status_securenets = 0;
222 #ifdef TCP_WRAPPER
223 int status_tcpwrap;
224 #endif
225 static unsigned long oldaddr = 0;
226 struct securenet *tmp;
227 const char *yp_procedure = NULL;
228 char procbuf[50];
229
230 if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
231 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu",
232 (unsigned long)rqstp->rq_prog,
233 (unsigned long)rqstp->rq_proc);
234 yp_procedure = (char *)&procbuf;
235 } else {
236 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
237 "yppasswdprog_update" :
238 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
239 }
240
241 rqhost = svc_getcaller(rqstp->rq_xprt);
242
243 if (debug) {
244 yp_error("procedure %s called from %s:%d", yp_procedure,
245 inet_ntoa(rqhost->sin_addr),
246 ntohs(rqhost->sin_port));
247 if (map != NULL)
248 yp_error("client is referencing map \"%s\".", map);
249 }
250
251 /* Check the map name if one was supplied. */
252 if (map != NULL) {
253 if (strchr(map, '/')) {
254 yp_error("embedded slash in map name \"%s\" -- \
255 possible spoof attempt from %s:%d",
256 map, inet_ntoa(rqhost->sin_addr),
257 ntohs(rqhost->sin_port));
258 return(1);
259 }
260 #ifdef DB_CACHE
261 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
262 #else
263 if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") ||
264 #endif
265 (rqstp->rq_prog == YPPROG &&
266 rqstp->rq_proc == YPPROC_XFR) ||
267 (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
268 rqstp->rq_proc == YPXFRD_GETMAP)) &&
269 ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
270 yp_error("access to %s denied -- client %s:%d \
271 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
272 return(1);
273 }
274 }
275
276 #ifdef TCP_WRAPPER
277 status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN,
278 inet_ntoa(rqhost->sin_addr), "");
279 #endif
280 tmp = securenets;
281 while (tmp) {
282 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
283 | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
284 status_securenets = 1;
285 break;
286 }
287 tmp = tmp->next;
288 }
289
290 #ifdef TCP_WRAPPER
291 if (status_securenets == 0 || status_tcpwrap == 0) {
292 #else
293 if (status_securenets == 0) {
294 #endif
295 /*
296 * One of the following two events occurred:
297 *
298 * (1) The /var/yp/securenets exists and the remote host does not
299 * match any of the networks specified in it.
300 * (2) The hosts.allow file has denied access and TCP_WRAPPER is
301 * defined.
302 *
303 * In either case deny access.
304 */
305 if (rqhost->sin_addr.s_addr != oldaddr) {
306 yp_error("connect from %s:%d to procedure %s refused",
307 inet_ntoa(rqhost->sin_addr),
308 ntohs(rqhost->sin_port),
309 yp_procedure);
310 oldaddr = rqhost->sin_addr.s_addr;
311 }
312 return(1);
313 }
314 return(0);
315
316 }
317
318 int
319 yp_validdomain(const char *domain)
320 {
321 struct stat statbuf;
322 char dompath[MAXPATHLEN + 2];
323
324 if (domain == NULL || strstr(domain, "binding") ||
325 !strcmp(domain, ".") || !strcmp(domain, "..") ||
326 strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
327 return(1);
328
329 snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);
330
331 if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
332 return(1);
333
334
335 return(0);
336 }
337