yp_access.c revision 96221 
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#ifndef lint
35static const char rcsid[] =
36  "$FreeBSD: head/usr.sbin/ypserv/yp_access.c 96221 2002-05-08 15:41:15Z des $";
37#endif /* not lint */
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
60extern int debug;
61
62			/* NIS v1 */
63const char *yp_procs[] = {
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#ifdef TCP_WRAPPER
93void
94load_securenets(void)
95{
96}
97#else
98struct securenet {
99	struct in_addr net;
100	struct in_addr mask;
101	struct securenet *next;
102};
103
104struct securenet *securenets;
105
106#define LINEBUFSZ 1024
107
108/*
109 * Read /var/yp/securenets file and initialize the securenets
110 * list. If the file doesn't exist, we set up a dummy entry that
111 * allows all hosts to connect.
112 */
113void
114load_securenets(void)
115{
116	FILE *fp;
117	char path[MAXPATHLEN + 2];
118	char linebuf[1024 + 2];
119	struct securenet *tmp;
120
121	/*
122	 * If securenets is not NULL, we are being called to reload
123	 * the list; free the existing list before re-reading the
124	 * securenets file.
125	 */
126	while (securenets) {
127		tmp = securenets->next;
128		free(securenets);
129		securenets = tmp;
130	}
131
132	snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);
133
134	if ((fp = fopen(path, "r")) == NULL) {
135		if (errno == ENOENT) {
136			securenets = (struct securenet *)malloc(sizeof(struct securenet));
137			securenets->net.s_addr = INADDR_ANY;
138			securenets->mask.s_addr = INADDR_ANY;
139			securenets->next = NULL;
140			return;
141		} else {
142			yp_error("fopen(%s) failed: %s", path, strerror(errno));
143			exit(1);
144		}
145	}
146
147	securenets = NULL;
148
149	while (fgets(linebuf, LINEBUFSZ, fp)) {
150		char addr1[20], addr2[20];
151
152		if ((linebuf[0] == '#')
153		    || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
154			continue;
155		if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
156			yp_error("badly formatted securenets entry: %s",
157							linebuf);
158			continue;
159		}
160
161		tmp = (struct securenet *)malloc(sizeof(struct securenet));
162
163		if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
164			yp_error("badly formatted securenets entry: %s", addr1);
165			free(tmp);
166			continue;
167		}
168
169		if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
170			yp_error("badly formatted securenets entry: %s", addr2);
171			free(tmp);
172			continue;
173		}
174
175		tmp->next = securenets;
176		securenets = tmp;
177	}
178
179	fclose(fp);
180
181}
182#endif
183
184/*
185 * Access control functions.
186 *
187 * yp_access() checks the mapname and client host address and watches for
188 * the following things:
189 *
190 * - If the client is referencing one of the master.passwd.* maps, it must
191 *   be using a privileged port to make its RPC to us. If it is, then we can
192 *   assume that the caller is root and allow the RPC to succeed. If it
193 *   isn't access is denied.
194 *
195 * - The client's IP address is checked against the securenets rules.
196 *   There are two kinds of securenets support: the built-in support,
197 *   which is very simple and depends on the presence of a
198 *   /var/yp/securenets file, and tcp-wrapper support, which requires
199 *   Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
200 *   package does not ship with FreeBSD, we use the built-in support
201 *   by default. Users can recompile the server with the tcp-wrapper library
202 *   if they already have it installed and want to use hosts.allow and
203 *   hosts.deny to control access instead of having a separate securenets
204 *   file.)
205 *
206 *   If no /var/yp/securenets file is present, the host access checks
207 *   are bypassed and all hosts are allowed to connect.
208 *
209 * The yp_validdomain() function checks the domain specified by the caller
210 * to make sure it's actually served by this server. This is more a sanity
211 * check than an a security check, but this seems to be the best place for
212 * it.
213 */
214
215#ifdef DB_CACHE
216int
217yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
218#else
219int
220yp_access(const char *map, const struct svc_req *rqstp)
221#endif
222{
223	struct sockaddr_in *rqhost;
224	int status = 0;
225	static unsigned long oldaddr = 0;
226#ifndef TCP_WRAPPER
227	struct securenet *tmp;
228#endif
229	const char *yp_procedure = NULL;
230	char procbuf[50];
231
232	if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
233		snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu",
234		    (unsigned long)rqstp->rq_prog,
235		    (unsigned long)rqstp->rq_proc);
236		yp_procedure = (char *)&procbuf;
237	} else {
238		yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
239		"yppasswdprog_update" :
240		yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
241	}
242
243	rqhost = svc_getcaller(rqstp->rq_xprt);
244
245	if (debug) {
246		yp_error("procedure %s called from %s:%d", yp_procedure,
247			inet_ntoa(rqhost->sin_addr),
248			ntohs(rqhost->sin_port));
249		if (map != NULL)
250			yp_error("client is referencing map \"%s\".", map);
251	}
252
253	/* Check the map name if one was supplied. */
254	if (map != NULL) {
255		if (strchr(map, '/')) {
256			yp_error("embedded slash in map name \"%s\" -- \
257possible spoof attempt from %s:%d",
258				map, inet_ntoa(rqhost->sin_addr),
259				ntohs(rqhost->sin_port));
260			return(1);
261		}
262#ifdef DB_CACHE
263		if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
264#else
265		if ((strstr(map, "master.passwd.") ||
266#endif
267		    (rqstp->rq_prog == YPPROG &&
268		     rqstp->rq_proc == YPPROC_XFR) ||
269		    (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
270		     rqstp->rq_proc == YPXFRD_GETMAP)) &&
271		     ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
272			yp_error("access to %s denied -- client %s:%d \
273not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
274			return(1);
275		}
276	}
277
278#ifdef TCP_WRAPPER
279	status = hosts_ctl("ypserv", STRING_UNKNOWN,
280			   inet_ntoa(rqhost->sin_addr), "");
281#else
282	tmp = securenets;
283	while (tmp) {
284		if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
285		    | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
286			status = 1;
287			break;
288		}
289		tmp = tmp->next;
290	}
291#endif
292
293	if (!status) {
294		if (rqhost->sin_addr.s_addr != oldaddr) {
295			yp_error("connect from %s:%d to procedure %s refused",
296					inet_ntoa(rqhost->sin_addr),
297					ntohs(rqhost->sin_port),
298					yp_procedure);
299			oldaddr = rqhost->sin_addr.s_addr;
300		}
301		return(1);
302	}
303	return(0);
304
305}
306
307int
308yp_validdomain(const char *domain)
309{
310	struct stat statbuf;
311	char dompath[MAXPATHLEN + 2];
312
313	if (domain == NULL || strstr(domain, "binding") ||
314	    !strcmp(domain, ".") || !strcmp(domain, "..") ||
315	    strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
316		return(1);
317
318	snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);
319
320	if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
321		return(1);
322
323
324	return(0);
325}
326