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 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include <stdlib.h> 38 #include <rpc/rpc.h> 39 #include <rpcsvc/yp.h> 40 #include <rpcsvc/yppasswd.h> 41 #include <rpcsvc/ypxfrd.h> 42 #include <sys/types.h> 43 #include <limits.h> 44 #include <db.h> 45 #include <sys/socket.h> 46 #include <netinet/in.h> 47 #include <arpa/inet.h> 48 #include <sys/stat.h> 49 #include <sys/fcntl.h> 50 #include <paths.h> 51 #include <errno.h> 52 #include <sys/param.h> 53 #include "yp_extern.h" 54 #ifdef TCP_WRAPPER 55 #include "tcpd.h" 56 #endif 57 58 extern int debug; 59 60 /* NIS v1 */ 61 const char *yp_procs[] = { 62 "ypoldproc_null", 63 "ypoldproc_domain", 64 "ypoldproc_domain_nonack", 65 "ypoldproc_match", 66 "ypoldproc_first", 67 "ypoldproc_next", 68 "ypoldproc_poll", 69 "ypoldproc_push", 70 "ypoldproc_get", 71 "badproc1", /* placeholder */ 72 "badproc2", /* placeholder */ 73 "badproc3", /* placeholder */ 74 75 /* NIS v2 */ 76 "ypproc_null", 77 "ypproc_domain", 78 "ypproc_domain_nonack", 79 "ypproc_match", 80 "ypproc_first", 81 "ypproc_next", 82 "ypproc_xfr", 83 "ypproc_clear", 84 "ypproc_all", 85 "ypproc_master", 86 "ypproc_order", 87 "ypproc_maplist" 88 }; 89 90 struct securenet { 91 struct in_addr net; 92 struct in_addr mask; 93 struct securenet *next; 94 }; 95 96 struct securenet *securenets; 97 98 #define LINEBUFSZ 1024 99 100 /* 101 * Read /var/yp/securenets file and initialize the securenets 102 * list. If the file doesn't exist, we set up a dummy entry that 103 * allows all hosts to connect. 104 */ 105 void 106 load_securenets(void) 107 { 108 FILE *fp; 109 char path[MAXPATHLEN + 2]; 110 char linebuf[1024 + 2]; 111 struct securenet *tmp; 112 113 /* 114 * If securenets is not NULL, we are being called to reload 115 * the list; free the existing list before re-reading the 116 * securenets file. 117 */ 118 while (securenets) { 119 tmp = securenets->next; 120 free(securenets); 121 securenets = tmp; 122 } 123 124 snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir); 125 126 if ((fp = fopen(path, "r")) == NULL) { 127 if (errno == ENOENT) { 128 securenets = (struct securenet *)malloc(sizeof(struct securenet)); 129 securenets->net.s_addr = INADDR_ANY; 130 securenets->mask.s_addr = INADDR_ANY; 131 securenets->next = NULL; 132 return; 133 } else { 134 yp_error("fopen(%s) failed: %s", path, strerror(errno)); 135 exit(1); 136 } 137 } 138 139 securenets = NULL; 140 141 while (fgets(linebuf, LINEBUFSZ, fp)) { 142 char addr1[20], addr2[20]; 143 144 if ((linebuf[0] == '#') 145 || (strspn(linebuf, " \t\r\n") == strlen(linebuf))) 146 continue; 147 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) { 148 yp_error("badly formatted securenets entry: %s", 149 linebuf); 150 continue; 151 } 152 153 tmp = (struct securenet *)malloc(sizeof(struct securenet)); 154 155 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) { 156 yp_error("badly formatted securenets entry: %s", addr1); 157 free(tmp); 158 continue; 159 } 160 161 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) { 162 yp_error("badly formatted securenets entry: %s", addr2); 163 free(tmp); 164 continue; 165 } 166 167 tmp->next = securenets; 168 securenets = tmp; 169 } 170 171 fclose(fp); 172 173 } 174 175 /* 176 * Access control functions. 177 * 178 * yp_access() checks the mapname and client host address and watches for 179 * the following things: 180 * 181 * - If the client is referencing one of the master.passwd.* or shadow.* maps, 182 * it must be using a privileged port to make its RPC to us. If it is, then 183 * we can assume that the caller is root and allow the RPC to succeed. If it 184 * isn't access is denied. 185 * 186 * - The client's IP address is checked against the securenets rules. 187 * There are two kinds of securenets support: the built-in support, 188 * which is very simple and depends on the presence of a 189 * /var/yp/securenets file, and tcp-wrapper support, which requires 190 * Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper 191 * package does not ship with FreeBSD, we use the built-in support 192 * by default. Users can recompile the server with the tcp-wrapper library 193 * if they already have it installed and want to use hosts.allow and 194 * hosts.deny to control access instead of having a separate securenets 195 * file.) 196 * 197 * If no /var/yp/securenets file is present, the host access checks 198 * are bypassed and all hosts are allowed to connect. 199 * 200 * The yp_validdomain() function checks the domain specified by the caller 201 * to make sure it's actually served by this server. This is more a sanity 202 * check than an a security check, but this seems to be the best place for 203 * it. 204 */ 205 206 #ifdef DB_CACHE 207 int 208 yp_access(const char *map, const char *domain, const struct svc_req *rqstp) 209 #else 210 int 211 yp_access(const char *map, const struct svc_req *rqstp) 212 #endif 213 { 214 struct sockaddr_in *rqhost; 215 int status_securenets = 0; 216 #ifdef TCP_WRAPPER 217 int status_tcpwrap; 218 #endif 219 static unsigned long oldaddr = 0; 220 struct securenet *tmp; 221 const char *yp_procedure = NULL; 222 char procbuf[50]; 223 224 if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) { 225 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu", 226 (unsigned long)rqstp->rq_prog, 227 (unsigned long)rqstp->rq_proc); 228 yp_procedure = (char *)&procbuf; 229 } else { 230 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ? 231 "yppasswdprog_update" : 232 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))]; 233 } 234 235 rqhost = svc_getcaller(rqstp->rq_xprt); 236 237 if (debug) { 238 yp_error("procedure %s called from %s:%d", yp_procedure, 239 inet_ntoa(rqhost->sin_addr), 240 ntohs(rqhost->sin_port)); 241 if (map != NULL) 242 yp_error("client is referencing map \"%s\".", map); 243 } 244 245 /* Check the map name if one was supplied. */ 246 if (map != NULL) { 247 if (strchr(map, '/')) { 248 yp_error("embedded slash in map name \"%s\" -- \ 249 possible spoof attempt from %s:%d", 250 map, inet_ntoa(rqhost->sin_addr), 251 ntohs(rqhost->sin_port)); 252 return(1); 253 } 254 #ifdef DB_CACHE 255 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) || 256 #else 257 if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") || 258 #endif 259 (rqstp->rq_prog == YPPROG && 260 rqstp->rq_proc == YPPROC_XFR) || 261 (rqstp->rq_prog == YPXFRD_FREEBSD_PROG && 262 rqstp->rq_proc == YPXFRD_GETMAP)) && 263 ntohs(rqhost->sin_port) >= IPPORT_RESERVED) { 264 yp_error("access to %s denied -- client %s:%d \ 265 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port)); 266 return(1); 267 } 268 } 269 270 #ifdef TCP_WRAPPER 271 status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN, 272 inet_ntoa(rqhost->sin_addr), ""); 273 #endif 274 tmp = securenets; 275 while (tmp) { 276 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr) 277 | tmp->net.s_addr) == rqhost->sin_addr.s_addr) { 278 status_securenets = 1; 279 break; 280 } 281 tmp = tmp->next; 282 } 283 284 #ifdef TCP_WRAPPER 285 if (status_securenets == 0 || status_tcpwrap == 0) { 286 #else 287 if (status_securenets == 0) { 288 #endif 289 /* 290 * One of the following two events occurred: 291 * 292 * (1) The /var/yp/securenets exists and the remote host does not 293 * match any of the networks specified in it. 294 * (2) The hosts.allow file has denied access and TCP_WRAPPER is 295 * defined. 296 * 297 * In either case deny access. 298 */ 299 if (rqhost->sin_addr.s_addr != oldaddr) { 300 yp_error("connect from %s:%d to procedure %s refused", 301 inet_ntoa(rqhost->sin_addr), 302 ntohs(rqhost->sin_port), 303 yp_procedure); 304 oldaddr = rqhost->sin_addr.s_addr; 305 } 306 return(1); 307 } 308 return(0); 309 310 } 311 312 int 313 yp_validdomain(const char *domain) 314 { 315 struct stat statbuf; 316 char dompath[MAXPATHLEN + 2]; 317 318 if (domain == NULL || strstr(domain, "binding") || 319 !strcmp(domain, ".") || !strcmp(domain, "..") || 320 strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN) 321 return(1); 322 323 snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain); 324 325 if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode)) 326 return(1); 327 328 329 return(0); 330 } 331