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
58static 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
88struct securenet {
89	struct in_addr net;
90	struct in_addr mask;
91	struct securenet *next;
92};
93
94static struct securenet *securenets;
95
96#define LINEBUFSZ 1024
97
98#ifdef TCP_WRAPPER
99int 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 */
107void
108load_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
209int
210yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
211#else
212int
213yp_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\" -- \
251possible 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 \
267not 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
314int
315yp_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