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 } 327