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