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