1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1995 5 * Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Bill Paul. 18 * 4. Neither the name of the author nor the names of any co-contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 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 60 extern int debug; 61 62 static const char *yp_procs[] = { 63 /* NIS v1 */ 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 struct securenet { 93 struct in_addr net; 94 struct in_addr mask; 95 struct securenet *next; 96 }; 97 98 static struct securenet *securenets; 99 100 #define LINEBUFSZ 1024 101 102 #ifdef TCP_WRAPPER 103 int hosts_ctl(char *, char *, char *, char *); 104 #endif 105 106 /* 107 * Read /var/yp/securenets file and initialize the securenets 108 * list. If the file doesn't exist, we set up a dummy entry that 109 * allows all hosts to connect. 110 */ 111 void 112 load_securenets(void) 113 { 114 FILE *fp; 115 char path[MAXPATHLEN + 2]; 116 char linebuf[1024 + 2]; 117 struct securenet *tmp; 118 119 /* 120 * If securenets is not NULL, we are being called to reload 121 * the list; free the existing list before re-reading the 122 * securenets file. 123 */ 124 while (securenets) { 125 tmp = securenets->next; 126 free(securenets); 127 securenets = tmp; 128 } 129 130 snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir); 131 132 if ((fp = fopen(path, "r")) == NULL) { 133 if (errno == ENOENT) { 134 securenets = malloc(sizeof(struct securenet)); 135 securenets->net.s_addr = INADDR_ANY; 136 securenets->mask.s_addr = INADDR_ANY; 137 securenets->next = NULL; 138 return; 139 } else { 140 yp_error("fopen(%s) failed: %s", path, strerror(errno)); 141 exit(1); 142 } 143 } 144 145 securenets = NULL; 146 147 while (fgets(linebuf, LINEBUFSZ, fp)) { 148 char addr1[20], addr2[20]; 149 150 if ((linebuf[0] == '#') 151 || (strspn(linebuf, " \t\r\n") == strlen(linebuf))) 152 continue; 153 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) { 154 yp_error("badly formatted securenets entry: %s", 155 linebuf); 156 continue; 157 } 158 159 tmp = malloc(sizeof(struct securenet)); 160 161 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) { 162 yp_error("badly formatted securenets entry: %s", addr1); 163 free(tmp); 164 continue; 165 } 166 167 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) { 168 yp_error("badly formatted securenets entry: %s", addr2); 169 free(tmp); 170 continue; 171 } 172 173 tmp->next = securenets; 174 securenets = tmp; 175 } 176 177 fclose(fp); 178 179 } 180 181 /* 182 * Access control functions. 183 * 184 * yp_access() checks the mapname and client host address and watches for 185 * the following things: 186 * 187 * - If the client is referencing one of the master.passwd.* or shadow.* maps, 188 * it must be using a privileged port to make its RPC to us. If it is, then 189 * we can assume that the caller is root and allow the RPC to succeed. If it 190 * isn't access is denied. 191 * 192 * - The client's IP address is checked against the securenets rules. 193 * There are two kinds of securenets support: the built-in support, 194 * which is very simple and depends on the presence of a 195 * /var/yp/securenets file, and tcp-wrapper support, which requires 196 * Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper 197 * package does not ship with FreeBSD, we use the built-in support 198 * by default. Users can recompile the server with the tcp-wrapper library 199 * if they already have it installed and want to use hosts.allow and 200 * hosts.deny to control access instead of having a separate securenets 201 * file.) 202 * 203 * If no /var/yp/securenets file is present, the host access checks 204 * are bypassed and all hosts are allowed to connect. 205 * 206 * The yp_validdomain() function checks the domain specified by the caller 207 * to make sure it's actually served by this server. This is more a sanity 208 * check than an a security check, but this seems to be the best place for 209 * it. 210 */ 211 212 #ifdef DB_CACHE 213 int 214 yp_access(const char *map, const char *domain, const struct svc_req *rqstp) 215 #else 216 int 217 yp_access(const char *map, const struct svc_req *rqstp) 218 #endif 219 { 220 struct sockaddr_in *rqhost; 221 int status_securenets = 0; 222 #ifdef TCP_WRAPPER 223 int status_tcpwrap; 224 #endif 225 static unsigned long oldaddr = 0; 226 struct securenet *tmp; 227 const char *yp_procedure = NULL; 228 char procbuf[50]; 229 230 if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) { 231 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu", 232 (unsigned long)rqstp->rq_prog, 233 (unsigned long)rqstp->rq_proc); 234 yp_procedure = (char *)&procbuf; 235 } else { 236 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ? 237 "yppasswdprog_update" : 238 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))]; 239 } 240 241 rqhost = svc_getcaller(rqstp->rq_xprt); 242 243 if (debug) { 244 yp_error("procedure %s called from %s:%d", yp_procedure, 245 inet_ntoa(rqhost->sin_addr), 246 ntohs(rqhost->sin_port)); 247 if (map != NULL) 248 yp_error("client is referencing map \"%s\".", map); 249 } 250 251 /* Check the map name if one was supplied. */ 252 if (map != NULL) { 253 if (strchr(map, '/')) { 254 yp_error("embedded slash in map name \"%s\" -- \ 255 possible spoof attempt from %s:%d", 256 map, inet_ntoa(rqhost->sin_addr), 257 ntohs(rqhost->sin_port)); 258 return(1); 259 } 260 #ifdef DB_CACHE 261 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) || 262 #else 263 if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") || 264 #endif 265 (rqstp->rq_prog == YPPROG && 266 rqstp->rq_proc == YPPROC_XFR) || 267 (rqstp->rq_prog == YPXFRD_FREEBSD_PROG && 268 rqstp->rq_proc == YPXFRD_GETMAP)) && 269 ntohs(rqhost->sin_port) >= IPPORT_RESERVED) { 270 yp_error("access to %s denied -- client %s:%d \ 271 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port)); 272 return(1); 273 } 274 } 275 276 #ifdef TCP_WRAPPER 277 status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN, 278 inet_ntoa(rqhost->sin_addr), ""); 279 #endif 280 tmp = securenets; 281 while (tmp) { 282 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr) 283 | tmp->net.s_addr) == rqhost->sin_addr.s_addr) { 284 status_securenets = 1; 285 break; 286 } 287 tmp = tmp->next; 288 } 289 290 #ifdef TCP_WRAPPER 291 if (status_securenets == 0 || status_tcpwrap == 0) { 292 #else 293 if (status_securenets == 0) { 294 #endif 295 /* 296 * One of the following two events occurred: 297 * 298 * (1) The /var/yp/securenets exists and the remote host does not 299 * match any of the networks specified in it. 300 * (2) The hosts.allow file has denied access and TCP_WRAPPER is 301 * defined. 302 * 303 * In either case deny access. 304 */ 305 if (rqhost->sin_addr.s_addr != oldaddr) { 306 yp_error("connect from %s:%d to procedure %s refused", 307 inet_ntoa(rqhost->sin_addr), 308 ntohs(rqhost->sin_port), 309 yp_procedure); 310 oldaddr = rqhost->sin_addr.s_addr; 311 } 312 return(1); 313 } 314 return(0); 315 316 } 317 318 int 319 yp_validdomain(const char *domain) 320 { 321 struct stat statbuf; 322 char dompath[MAXPATHLEN + 2]; 323 324 if (domain == NULL || strstr(domain, "binding") || 325 !strcmp(domain, ".") || !strcmp(domain, "..") || 326 strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN) 327 return(1); 328 329 snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain); 330 331 if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode)) 332 return(1); 333 334 335 return(0); 336 } 337