1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1995
5 * Bill Paul <wpaul@ctr.columbia.edu>. 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 #include <stdlib.h>
38 #include <rpc/rpc.h>
39 #include <rpcsvc/yp.h>
40 #include <rpcsvc/yppasswd.h>
41 #include <rpcsvc/ypxfrd.h>
42 #include <sys/types.h>
43 #include <limits.h>
44 #include <db.h>
45 #include <sys/socket.h>
46 #include <netinet/in.h>
47 #include <arpa/inet.h>
48 #include <sys/stat.h>
49 #include <sys/fcntl.h>
50 #include <paths.h>
51 #include <errno.h>
52 #include <sys/param.h>
53 #include "yp_extern.h"
54 #ifdef TCP_WRAPPER
55 #include "tcpd.h"
56 #endif
57
58 static const char *yp_procs[] = {
59 /* NIS v1 */
60 "ypoldproc_null",
61 "ypoldproc_domain",
62 "ypoldproc_domain_nonack",
63 "ypoldproc_match",
64 "ypoldproc_first",
65 "ypoldproc_next",
66 "ypoldproc_poll",
67 "ypoldproc_push",
68 "ypoldproc_get",
69 "badproc1", /* placeholder */
70 "badproc2", /* placeholder */
71 "badproc3", /* placeholder */
72
73 /* NIS v2 */
74 "ypproc_null",
75 "ypproc_domain",
76 "ypproc_domain_nonack",
77 "ypproc_match",
78 "ypproc_first",
79 "ypproc_next",
80 "ypproc_xfr",
81 "ypproc_clear",
82 "ypproc_all",
83 "ypproc_master",
84 "ypproc_order",
85 "ypproc_maplist"
86 };
87
88 struct securenet {
89 struct in_addr net;
90 struct in_addr mask;
91 struct securenet *next;
92 };
93
94 static struct securenet *securenets;
95
96 #define LINEBUFSZ 1024
97
98 #ifdef TCP_WRAPPER
99 int hosts_ctl(char *, char *, char *, char *);
100 #endif
101
102 /*
103 * Read /var/yp/securenets file and initialize the securenets
104 * list. If the file doesn't exist, we set up a dummy entry that
105 * allows all hosts to connect.
106 */
107 void
load_securenets(void)108 load_securenets(void)
109 {
110 FILE *fp;
111 char path[MAXPATHLEN + 2];
112 char linebuf[1024 + 2];
113 struct securenet *tmp;
114
115 /*
116 * If securenets is not NULL, we are being called to reload
117 * the list; free the existing list before re-reading the
118 * securenets file.
119 */
120 while (securenets) {
121 tmp = securenets->next;
122 free(securenets);
123 securenets = tmp;
124 }
125
126 snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);
127
128 if ((fp = fopen(path, "r")) == NULL) {
129 if (errno == ENOENT) {
130 securenets = malloc(sizeof(struct securenet));
131 securenets->net.s_addr = INADDR_ANY;
132 securenets->mask.s_addr = INADDR_ANY;
133 securenets->next = NULL;
134 return;
135 } else {
136 yp_error("fopen(%s) failed: %s", path, strerror(errno));
137 exit(1);
138 }
139 }
140
141 securenets = NULL;
142
143 while (fgets(linebuf, LINEBUFSZ, fp)) {
144 char addr1[20], addr2[20];
145
146 if ((linebuf[0] == '#')
147 || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
148 continue;
149 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
150 yp_error("badly formatted securenets entry: %s",
151 linebuf);
152 continue;
153 }
154
155 tmp = malloc(sizeof(struct securenet));
156
157 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
158 yp_error("badly formatted securenets entry: %s", addr1);
159 free(tmp);
160 continue;
161 }
162
163 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
164 yp_error("badly formatted securenets entry: %s", addr2);
165 free(tmp);
166 continue;
167 }
168
169 tmp->next = securenets;
170 securenets = tmp;
171 }
172
173 fclose(fp);
174
175 }
176
177 /*
178 * Access control functions.
179 *
180 * yp_access() checks the mapname and client host address and watches for
181 * the following things:
182 *
183 * - If the client is referencing one of the master.passwd.* or shadow.* maps,
184 * it must be using a privileged port to make its RPC to us. If it is, then
185 * we can assume that the caller is root and allow the RPC to succeed. If it
186 * isn't access is denied.
187 *
188 * - The client's IP address is checked against the securenets rules.
189 * There are two kinds of securenets support: the built-in support,
190 * which is very simple and depends on the presence of a
191 * /var/yp/securenets file, and tcp-wrapper support, which requires
192 * Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
193 * package does not ship with FreeBSD, we use the built-in support
194 * by default. Users can recompile the server with the tcp-wrapper library
195 * if they already have it installed and want to use hosts.allow and
196 * hosts.deny to control access instead of having a separate securenets
197 * file.)
198 *
199 * If no /var/yp/securenets file is present, the host access checks
200 * are bypassed and all hosts are allowed to connect.
201 *
202 * The yp_validdomain() function checks the domain specified by the caller
203 * to make sure it's actually served by this server. This is more a sanity
204 * check than an a security check, but this seems to be the best place for
205 * it.
206 */
207
208 #ifdef DB_CACHE
209 int
yp_access(const char * map,const char * domain,const struct svc_req * rqstp)210 yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
211 #else
212 int
213 yp_access(const char *map, const struct svc_req *rqstp)
214 #endif
215 {
216 struct sockaddr_in *rqhost;
217 int status_securenets = 0;
218 #ifdef TCP_WRAPPER
219 int status_tcpwrap;
220 #endif
221 static unsigned long oldaddr = 0;
222 struct securenet *tmp;
223 const char *yp_procedure = NULL;
224 char procbuf[50];
225
226 if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
227 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu",
228 (unsigned long)rqstp->rq_prog,
229 (unsigned long)rqstp->rq_proc);
230 yp_procedure = (char *)&procbuf;
231 } else {
232 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
233 "yppasswdprog_update" :
234 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
235 }
236
237 rqhost = svc_getcaller(rqstp->rq_xprt);
238
239 if (debug) {
240 yp_error("procedure %s called from %s:%d", yp_procedure,
241 inet_ntoa(rqhost->sin_addr),
242 ntohs(rqhost->sin_port));
243 if (map != NULL)
244 yp_error("client is referencing map \"%s\".", map);
245 }
246
247 /* Check the map name if one was supplied. */
248 if (map != NULL) {
249 if (strchr(map, '/')) {
250 yp_error("embedded slash in map name \"%s\" -- \
251 possible spoof attempt from %s:%d",
252 map, inet_ntoa(rqhost->sin_addr),
253 ntohs(rqhost->sin_port));
254 return(1);
255 }
256 #ifdef DB_CACHE
257 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
258 #else
259 if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") ||
260 #endif
261 (rqstp->rq_prog == YPPROG &&
262 rqstp->rq_proc == YPPROC_XFR) ||
263 (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
264 rqstp->rq_proc == YPXFRD_GETMAP)) &&
265 ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
266 yp_error("access to %s denied -- client %s:%d \
267 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
268 return(1);
269 }
270 }
271
272 #ifdef TCP_WRAPPER
273 status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN,
274 inet_ntoa(rqhost->sin_addr), "");
275 #endif
276 tmp = securenets;
277 while (tmp) {
278 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
279 | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
280 status_securenets = 1;
281 break;
282 }
283 tmp = tmp->next;
284 }
285
286 #ifdef TCP_WRAPPER
287 if (status_securenets == 0 || status_tcpwrap == 0) {
288 #else
289 if (status_securenets == 0) {
290 #endif
291 /*
292 * One of the following two events occurred:
293 *
294 * (1) The /var/yp/securenets exists and the remote host does not
295 * match any of the networks specified in it.
296 * (2) The hosts.allow file has denied access and TCP_WRAPPER is
297 * defined.
298 *
299 * In either case deny access.
300 */
301 if (rqhost->sin_addr.s_addr != oldaddr) {
302 yp_error("connect from %s:%d to procedure %s refused",
303 inet_ntoa(rqhost->sin_addr),
304 ntohs(rqhost->sin_port),
305 yp_procedure);
306 oldaddr = rqhost->sin_addr.s_addr;
307 }
308 return(1);
309 }
310 return(0);
311
312 }
313
314 int
315 yp_validdomain(const char *domain)
316 {
317 struct stat statbuf;
318 char dompath[MAXPATHLEN + 2];
319
320 if (domain == NULL || strstr(domain, "binding") ||
321 !strcmp(domain, ".") || !strcmp(domain, "..") ||
322 strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
323 return(1);
324
325 snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);
326
327 if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
328 return(1);
329
330
331 return(0);
332 }
333