usr.sbin/ypserv/yp_access.c

   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  * $FreeBSD: src/usr.sbin/ypserv/yp_access.c,v 1.23 2006/05/31 22:31:08 cperciva Exp $
  33  * $DragonFly: src/usr.sbin/ypserv/yp_access.c,v 1.5 2006/06/13 12:38:37 corecode Exp $
  34  */
  35
  36 #include <stdlib.h>
  37 #include <rpc/rpc.h>
  38 #include <rpcsvc/yp.h>
  39 #include <rpcsvc/yppasswd.h>
  40 #include <rpcsvc/ypxfrd.h>
  41 #include <sys/types.h>
  42 #include <limits.h>
  43 #include <db.h>
  44 #include <sys/socket.h>
  45 #include <netinet/in.h>
  46 #include <arpa/inet.h>
  47 #include <sys/stat.h>
  48 #include <sys/fcntl.h>
  49 #include <paths.h>
  50 #include <errno.h>
  51 #include <sys/param.h>
  52 #include "yp_extern.h"
  53 #ifdef TCP_WRAPPER
  54 #include "tcpd.h"
  55 #endif
  56
  57 extern int debug;
  58
  59                         /* NIS v1 */
  60 const char *yp_procs[] = {
  61         "ypoldproc_null",
  62         "ypoldproc_domain",
  63         "ypoldproc_domain_nonack",
  64         "ypoldproc_match",
  65         "ypoldproc_first",
  66         "ypoldproc_next",
  67         "ypoldproc_poll",
  68         "ypoldproc_push",
  69         "ypoldproc_get",
  70         "badproc1", /* placeholder */
  71         "badproc2", /* placeholder */
  72         "badproc3", /* placeholder */
  73
  74         /* NIS v2 */
  75         "ypproc_null",
  76         "ypproc_domain",
  77         "ypproc_domain_nonack",
  78         "ypproc_match",
  79         "ypproc_first",
  80         "ypproc_next",
  81         "ypproc_xfr",
  82         "ypproc_clear",
  83         "ypproc_all",
  84         "ypproc_master",
  85         "ypproc_order",
  86         "ypproc_maplist"
  87 };
  88
  89 struct securenet {
  90         struct in_addr net;
  91         struct in_addr mask;
  92         struct securenet *next;
  93 };
  94
  95 struct securenet *securenets;
  96
  97 #define LINEBUFSZ 1024
  98
  99 /*
 100  * Read /var/yp/securenets file and initialize the securenets
 101  * list. If the file doesn't exist, we set up a dummy entry that
 102  * allows all hosts to connect.
 103  */
 104 void
 105 load_securenets(void)
 106 {
 107         FILE *fp;
 108         char path[MAXPATHLEN + 2];
 109         char linebuf[1024 + 2];
 110         struct securenet *tmp;
 111
 112         /*
 113          * If securenets is not NULL, we are being called to reload
 114          * the list; free the existing list before re-reading the
 115          * securenets file.
 116          */
 117         while (securenets) {
 118                 tmp = securenets->next;
 119                 free(securenets);
 120                 securenets = tmp;
 121         }
 122
 123         snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);
 124
 125         if ((fp = fopen(path, "r")) == NULL) {
 126                 if (errno == ENOENT) {
 127                         securenets = (struct securenet *)malloc(sizeof(struct securenet));
 128                         securenets->net.s_addr = INADDR_ANY;
 129                         securenets->mask.s_addr = INADDR_ANY;
 130                         securenets->next = NULL;
 131                         return;
 132                 } else {
 133                         yp_error("fopen(%s) failed: %s", path, strerror(errno));
 134                         exit(1);
 135                 }
 136         }
 137
 138         securenets = NULL;
 139
 140         while (fgets(linebuf, LINEBUFSZ, fp)) {
 141                 char addr1[20], addr2[20];
 142
 143                 if ((linebuf[0] == '#')
 144                     || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
 145                         continue;
 146                 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
 147                         yp_error("badly formatted securenets entry: %s",
 148                                                         linebuf);
 149                         continue;
 150                 }
 151
 152                 tmp = (struct securenet *)malloc(sizeof(struct securenet));
 153
 154                 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
 155                         yp_error("badly formatted securenets entry: %s", addr1);
 156                         free(tmp);
 157                         continue;
 158                 }
 159
 160                 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
 161                         yp_error("badly formatted securenets entry: %s", addr2);
 162                         free(tmp);
 163                         continue;
 164                 }
 165
 166                 tmp->next = securenets;
 167                 securenets = tmp;
 168         }
 169
 170         fclose(fp);
 171
 172 }
 173
 174 /*
 175  * Access control functions.
 176  *
 177  * yp_access() checks the mapname and client host address and watches for
 178  * the following things:
 179  *
 180  * - If the client is referencing one of the master.passwd.* maps, it must
 181  *   be using a privileged port to make its RPC to us. If it is, then we can
 182  *   assume that the caller is root and allow the RPC to succeed. If it
 183  *   isn't access is denied.
 184  *
 185  * - The client's IP address is checked against the securenets rules.
 186  *   There are two kinds of securenets support: the built-in support,
 187  *   which is very simple and depends on the presence of a
 188  *   /var/yp/securenets file, and tcp-wrapper support, which requires
 189  *   Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
 190  *   package does not ship with FreeBSD, we use the built-in support
 191  *   by default. Users can recompile the server with the tcp-wrapper library
 192  *   if they already have it installed and want to use hosts.allow and
 193  *   hosts.deny to control access instead of having a separate securenets
 194  *   file.)
 195  *
 196  *   If no /var/yp/securenets file is present, the host access checks
 197  *   are bypassed and all hosts are allowed to connect.
 198  *
 199  * The yp_validdomain() function checks the domain specified by the caller
 200  * to make sure it's actually served by this server. This is more a sanity
 201  * check than an a security check, but this seems to be the best place for
 202  * it.
 203  */
 204
 205 #ifdef DB_CACHE
 206 int
 207 yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
 208 #else
 209 int
 210 yp_access(const char *map, const struct svc_req *rqstp)
 211 #endif
 212 {
 213         struct sockaddr_in *rqhost;
 214         int status_securenets = 0;
 215 #ifdef TCP_WRAPPER
 216         int status_tcpwrap;
 217 #endif
 218         static unsigned long oldaddr = 0;
 219         struct securenet *tmp;
 220         const char *yp_procedure = NULL;
 221         char procbuf[50];
 222
 223         if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
 224                 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu",
 225                     (unsigned long)rqstp->rq_prog,
 226                     (unsigned long)rqstp->rq_proc);
 227                 yp_procedure = (char *)&procbuf;
 228         } else {
 229                 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
 230                 "yppasswdprog_update" :
 231                 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
 232         }
 233
 234         rqhost = svc_getcaller(rqstp->rq_xprt);
 235
 236         if (debug) {
 237                 yp_error("procedure %s called from %s:%d", yp_procedure,
 238                         inet_ntoa(rqhost->sin_addr),
 239                         ntohs(rqhost->sin_port));
 240                 if (map != NULL)
 241                         yp_error("client is referencing map \"%s\".", map);
 242         }
 243
 244         /* Check the map name if one was supplied. */
 245         if (map != NULL) {
 246                 if (strchr(map, '/')) {
 247                         yp_error("embedded slash in map name \"%s\" -- \
 248 possible spoof attempt from %s:%d",
 249                                 map, inet_ntoa(rqhost->sin_addr),
 250                                 ntohs(rqhost->sin_port));
 251                         return(1);
 252                 }
 253 #ifdef DB_CACHE
 254                 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
 255 #else
 256                 if ((strstr(map, "master.passwd.") ||
 257 #endif
 258                     (rqstp->rq_prog == YPPROG &&
 259                      rqstp->rq_proc == YPPROC_XFR) ||
 260                     (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
 261                      rqstp->rq_proc == YPXFRD_GETMAP)) &&
 262                      ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
 263                         yp_error("access to %s denied -- client %s:%d \
 264 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
 265                         return(1);
 266                 }
 267         }
 268
 269 #ifdef TCP_WRAPPER
 270         status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN,
 271                            inet_ntoa(rqhost->sin_addr), "");
 272 #endif
 273         tmp = securenets;
 274         while (tmp) {
 275                 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
 276                     | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
 277                         status_securenets = 1;
 278                         break;
 279                 }
 280                 tmp = tmp->next;
 281         }
 282
 283 #ifdef TCP_WRAPPER
 284         if (status_securenets == 0 || status_tcpwrap == 0) {
 285 #else
 286         if (status_securenets == 0) {
 287 #endif
 288         /*
 289          * One of the following two events occured:
 290          *
 291          * (1) The /var/yp/securenets exists and the remote host does not
 292          *     match any of the networks specified in it.
 293          * (2) The hosts.allow file has denied access and TCP_WRAPPER is
 294          *     defined.
 295          *
 296          * In either case deny access.
 297          */
 298                 if (rqhost->sin_addr.s_addr != oldaddr) {
 299                         yp_error("connect from %s:%d to procedure %s refused",
 300                                         inet_ntoa(rqhost->sin_addr),
 301                                         ntohs(rqhost->sin_port),
 302                                         yp_procedure);
 303                         oldaddr = rqhost->sin_addr.s_addr;
 304                 }
 305                 return(1);
 306         }
 307         return(0);
 308
 309 }
 310
 311 int
 312 yp_validdomain(const char *domain)
 313 {
 314         struct stat statbuf;
 315         char dompath[MAXPATHLEN + 2];
 316
 317         if (domain == NULL || strstr(domain, "binding") ||
 318             !strcmp(domain, ".") || !strcmp(domain, "..") ||
 319             strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
 320                 return(1);
 321
 322         snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);
 323
 324         if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
 325                 return(1);
 326
 327
 328         return(0);
 329 }