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 1.17.2.1 2002/02/15 00:47:00 des 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 char *yp_procs[] = {    "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 struct securenet *securenets;
  95
  96 #define LINEBUFSZ 1024
  97
  98 /*
  99  * Read /var/yp/securenets file and initialize the securenets
 100  * list. If the file doesn't exist, we set up a dummy entry that
 101  * allows all hosts to connect.
 102  */
 103 void
 104 load_securenets(void)
 105 {
 106         FILE *fp;
 107         char path[MAXPATHLEN + 2];
 108         char linebuf[1024 + 2];
 109         struct securenet *tmp;
 110
 111         /*
 112          * If securenets is not NULL, we are being called to reload
 113          * the list; free the existing list before re-reading the
 114          * securenets file.
 115          */
 116         while (securenets) {
 117                 tmp = securenets->next;
 118                 free(securenets);
 119                 securenets = tmp;
 120         }
 121
 122         snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir);
 123
 124         if ((fp = fopen(path, "r")) == NULL) {
 125                 if (errno == ENOENT) {
 126                         securenets = (struct securenet *)malloc(sizeof(struct securenet));
 127                         securenets->net.s_addr = INADDR_ANY;
 128                         securenets->mask.s_addr = INADDR_ANY;
 129                         securenets->next = NULL;
 130                         return;
 131                 } else {
 132                         yp_error("fopen(%s) failed: %s", path, strerror(errno));
 133                         exit(1);
 134                 }
 135         }
 136
 137         securenets = NULL;
 138
 139         while (fgets(linebuf, LINEBUFSZ, fp)) {
 140                 char addr1[20], addr2[20];
 141
 142                 if ((linebuf[0] == '#')
 143                     || (strspn(linebuf, " \t\r\n") == strlen(linebuf)))
 144                         continue;
 145                 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) {
 146                         yp_error("badly formatted securenets entry: %s",
 147                                                         linebuf);
 148                         continue;
 149                 }
 150
 151                 tmp = (struct securenet *)malloc(sizeof(struct securenet));
 152
 153                 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) {
 154                         yp_error("badly formatted securenets entry: %s", addr1);
 155                         free(tmp);
 156                         continue;
 157                 }
 158
 159                 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) {
 160                         yp_error("badly formatted securenets entry: %s", addr2);
 161                         free(tmp);
 162                         continue;
 163                 }
 164
 165                 tmp->next = securenets;
 166                 securenets = tmp;
 167         }
 168
 169         fclose(fp);
 170
 171 }
 172
 173 /*
 174  * Access control functions.
 175  *
 176  * yp_access() checks the mapname and client host address and watches for
 177  * the following things:
 178  *
 179  * - If the client is referencing one of the master.passwd.* maps, it must
 180  *   be using a privileged port to make its RPC to us. If it is, then we can
 181  *   assume that the caller is root and allow the RPC to succeed. If it
 182  *   isn't access is denied.
 183  *
 184  * - The client's IP address is checked against the securenets rules.
 185  *   There are two kinds of securenets support: the built-in support,
 186  *   which is very simple and depends on the presence of a
 187  *   /var/yp/securenets file, and tcp-wrapper support, which requires
 188  *   Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper
 189  *   package does not ship with FreeBSD, we use the built-in support
 190  *   by default. Users can recompile the server with the tcp-wrapper library
 191  *   if they already have it installed and want to use hosts.allow and
 192  *   hosts.deny to control access instead of having a separate securenets
 193  *   file.)
 194  *
 195  *   If no /var/yp/securenets file is present, the host access checks
 196  *   are bypassed and all hosts are allowed to connect.
 197  *
 198  * The yp_validdomain() function checks the domain specified by the caller
 199  * to make sure it's actually served by this server. This is more a sanity
 200  * check than an a security check, but this seems to be the best place for
 201  * it.
 202  */
 203
 204 #ifdef DB_CACHE
 205 int
 206 yp_access(const char *map, const char *domain, const struct svc_req *rqstp)
 207 #else
 208 int
 209 yp_access(const char *map, const struct svc_req *rqstp)
 210 #endif
 211 {
 212         struct sockaddr_in *rqhost;
 213         int status_securenets = 0;
 214 #ifdef TCP_WRAPPER
 215         int status_tcpwrap;
 216 #endif
 217         static unsigned long oldaddr = 0;
 218         struct securenet *tmp;
 219         char *yp_procedure = NULL;
 220         char procbuf[50];
 221
 222         if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) {
 223                 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu", rqstp->rq_prog,
 224                                                                 rqstp->rq_proc);
 225                 yp_procedure = (char *)&procbuf;
 226         } else {
 227                 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ?
 228                 "yppasswdprog_update" :
 229                 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))];
 230         }
 231
 232         rqhost = svc_getcaller(rqstp->rq_xprt);
 233
 234         if (debug) {
 235                 yp_error("procedure %s called from %s:%d", yp_procedure,
 236                         inet_ntoa(rqhost->sin_addr),
 237                         ntohs(rqhost->sin_port));
 238                 if (map != NULL)
 239                         yp_error("client is referencing map \"%s\".", map);
 240         }
 241
 242         /* Check the map name if one was supplied. */
 243         if (map != NULL) {
 244                 if (strchr(map, '/')) {
 245                         yp_error("embedded slash in map name \"%s\" -- \
 246 possible spoof attempt from %s:%d",
 247                                 map, inet_ntoa(rqhost->sin_addr),
 248                                 ntohs(rqhost->sin_port));
 249                         return(1);
 250                 }
 251 #ifdef DB_CACHE
 252                 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) ||
 253 #else
 254                 if ((strstr(map, "master.passwd.") ||
 255 #endif
 256                     (rqstp->rq_prog == YPPROG &&
 257                      rqstp->rq_proc == YPPROC_XFR) ||
 258                     (rqstp->rq_prog == YPXFRD_FREEBSD_PROG &&
 259                      rqstp->rq_proc == YPXFRD_GETMAP)) &&
 260                      ntohs(rqhost->sin_port) >= IPPORT_RESERVED) {
 261                         yp_error("access to %s denied -- client %s:%d \
 262 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port));
 263                         return(1);
 264                 }
 265         }
 266
 267 #ifdef TCP_WRAPPER
 268         status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN,
 269                            inet_ntoa(rqhost->sin_addr), "");
 270 #endif
 271         tmp = securenets;
 272         while (tmp) {
 273                 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr)
 274                     | tmp->net.s_addr) == rqhost->sin_addr.s_addr) {
 275                         status_securenets = 1;
 276                         break;
 277                 }
 278                 tmp = tmp->next;
 279         }
 280
 281 #ifdef TCP_WRAPPER
 282         if (status_securenets == 0 || status_tcpwrap == 0) {
 283 #else
 284         if (status_securenets == 0) {
 285 #endif
 286         /*
 287          * One of the following two events occured:
 288          *
 289          * (1) The /var/yp/securenets exists and the remote host does not
 290          *     match any of the networks specified in it.
 291          * (2) The hosts.allow file has denied access and TCP_WRAPPER is
 292          *     defined.
 293          *
 294          * In either case deny access.
 295          */
 296                 if (rqhost->sin_addr.s_addr != oldaddr) {
 297                         yp_error("connect from %s:%d to procedure %s refused",
 298                                         inet_ntoa(rqhost->sin_addr),
 299                                         ntohs(rqhost->sin_port),
 300                                         yp_procedure);
 301                         oldaddr = rqhost->sin_addr.s_addr;
 302                 }
 303                 return(1);
 304         }
 305         return(0);
 306
 307 }
 308
 309 int
 310 yp_validdomain(const char *domain)
 311 {
 312         struct stat statbuf;
 313         char dompath[MAXPATHLEN + 2];
 314
 315         if (domain == NULL || strstr(domain, "binding") ||
 316             !strcmp(domain, ".") || !strcmp(domain, "..") ||
 317             strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN)
 318                 return(1);
 319
 320         snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain);
 321
 322         if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode))
 323                 return(1);
 324
 325
 326         return(0);
 327 }