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 static const char *yp_procs[] = { 61 /* NIS v1 */ 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 static struct securenet *securenets; 97 98 #define LINEBUFSZ 1024 99 100 #ifdef TCP_WRAPPER 101 int hosts_ctl(char *, char *, char *, char *); 102 #endif 103 104 /* 105 * Read /var/yp/securenets file and initialize the securenets 106 * list. If the file doesn't exist, we set up a dummy entry that 107 * allows all hosts to connect. 108 */ 109 void 110 load_securenets(void) 111 { 112 FILE *fp; 113 char path[MAXPATHLEN + 2]; 114 char linebuf[1024 + 2]; 115 struct securenet *tmp; 116 117 /* 118 * If securenets is not NULL, we are being called to reload 119 * the list; free the existing list before re-reading the 120 * securenets file. 121 */ 122 while (securenets) { 123 tmp = securenets->next; 124 free(securenets); 125 securenets = tmp; 126 } 127 128 snprintf(path, MAXPATHLEN, "%s/securenets", yp_dir); 129 130 if ((fp = fopen(path, "r")) == NULL) { 131 if (errno == ENOENT) { 132 securenets = malloc(sizeof(struct securenet)); 133 securenets->net.s_addr = INADDR_ANY; 134 securenets->mask.s_addr = INADDR_ANY; 135 securenets->next = NULL; 136 return; 137 } else { 138 yp_error("fopen(%s) failed: %s", path, strerror(errno)); 139 exit(1); 140 } 141 } 142 143 securenets = NULL; 144 145 while (fgets(linebuf, LINEBUFSZ, fp)) { 146 char addr1[20], addr2[20]; 147 148 if ((linebuf[0] == '#') 149 || (strspn(linebuf, " \t\r\n") == strlen(linebuf))) 150 continue; 151 if (sscanf(linebuf, "%s %s", addr1, addr2) < 2) { 152 yp_error("badly formatted securenets entry: %s", 153 linebuf); 154 continue; 155 } 156 157 tmp = malloc(sizeof(struct securenet)); 158 159 if (!inet_aton((char *)&addr1, (struct in_addr *)&tmp->net)) { 160 yp_error("badly formatted securenets entry: %s", addr1); 161 free(tmp); 162 continue; 163 } 164 165 if (!inet_aton((char *)&addr2, (struct in_addr *)&tmp->mask)) { 166 yp_error("badly formatted securenets entry: %s", addr2); 167 free(tmp); 168 continue; 169 } 170 171 tmp->next = securenets; 172 securenets = tmp; 173 } 174 175 fclose(fp); 176 177 } 178 179 /* 180 * Access control functions. 181 * 182 * yp_access() checks the mapname and client host address and watches for 183 * the following things: 184 * 185 * - If the client is referencing one of the master.passwd.* or shadow.* maps, 186 * it must be using a privileged port to make its RPC to us. If it is, then 187 * we can assume that the caller is root and allow the RPC to succeed. If it 188 * isn't access is denied. 189 * 190 * - The client's IP address is checked against the securenets rules. 191 * There are two kinds of securenets support: the built-in support, 192 * which is very simple and depends on the presence of a 193 * /var/yp/securenets file, and tcp-wrapper support, which requires 194 * Wietse Venema's libwrap.a and tcpd.h. (Since the tcp-wrapper 195 * package does not ship with FreeBSD, we use the built-in support 196 * by default. Users can recompile the server with the tcp-wrapper library 197 * if they already have it installed and want to use hosts.allow and 198 * hosts.deny to control access instead of having a separate securenets 199 * file.) 200 * 201 * If no /var/yp/securenets file is present, the host access checks 202 * are bypassed and all hosts are allowed to connect. 203 * 204 * The yp_validdomain() function checks the domain specified by the caller 205 * to make sure it's actually served by this server. This is more a sanity 206 * check than an a security check, but this seems to be the best place for 207 * it. 208 */ 209 210 #ifdef DB_CACHE 211 int 212 yp_access(const char *map, const char *domain, const struct svc_req *rqstp) 213 #else 214 int 215 yp_access(const char *map, const struct svc_req *rqstp) 216 #endif 217 { 218 struct sockaddr_in *rqhost; 219 int status_securenets = 0; 220 #ifdef TCP_WRAPPER 221 int status_tcpwrap; 222 #endif 223 static unsigned long oldaddr = 0; 224 struct securenet *tmp; 225 const char *yp_procedure = NULL; 226 char procbuf[50]; 227 228 if (rqstp->rq_prog != YPPASSWDPROG && rqstp->rq_prog != YPPROG) { 229 snprintf(procbuf, sizeof(procbuf), "#%lu/#%lu", 230 (unsigned long)rqstp->rq_prog, 231 (unsigned long)rqstp->rq_proc); 232 yp_procedure = (char *)&procbuf; 233 } else { 234 yp_procedure = rqstp->rq_prog == YPPASSWDPROG ? 235 "yppasswdprog_update" : 236 yp_procs[rqstp->rq_proc + (12 * (rqstp->rq_vers - 1))]; 237 } 238 239 rqhost = svc_getcaller(rqstp->rq_xprt); 240 241 if (debug) { 242 yp_error("procedure %s called from %s:%d", yp_procedure, 243 inet_ntoa(rqhost->sin_addr), 244 ntohs(rqhost->sin_port)); 245 if (map != NULL) 246 yp_error("client is referencing map \"%s\".", map); 247 } 248 249 /* Check the map name if one was supplied. */ 250 if (map != NULL) { 251 if (strchr(map, '/')) { 252 yp_error("embedded slash in map name \"%s\" -- \ 253 possible spoof attempt from %s:%d", 254 map, inet_ntoa(rqhost->sin_addr), 255 ntohs(rqhost->sin_port)); 256 return(1); 257 } 258 #ifdef DB_CACHE 259 if ((yp_testflag((char *)map, (char *)domain, YP_SECURE) || 260 #else 261 if ((strstr(map, "master.passwd.") || strstr(map, "shadow.") || 262 #endif 263 (rqstp->rq_prog == YPPROG && 264 rqstp->rq_proc == YPPROC_XFR) || 265 (rqstp->rq_prog == YPXFRD_FREEBSD_PROG && 266 rqstp->rq_proc == YPXFRD_GETMAP)) && 267 ntohs(rqhost->sin_port) >= IPPORT_RESERVED) { 268 yp_error("access to %s denied -- client %s:%d \ 269 not privileged", map, inet_ntoa(rqhost->sin_addr), ntohs(rqhost->sin_port)); 270 return(1); 271 } 272 } 273 274 #ifdef TCP_WRAPPER 275 status_tcpwrap = hosts_ctl("ypserv", STRING_UNKNOWN, 276 inet_ntoa(rqhost->sin_addr), ""); 277 #endif 278 tmp = securenets; 279 while (tmp) { 280 if (((rqhost->sin_addr.s_addr & ~tmp->mask.s_addr) 281 | tmp->net.s_addr) == rqhost->sin_addr.s_addr) { 282 status_securenets = 1; 283 break; 284 } 285 tmp = tmp->next; 286 } 287 288 #ifdef TCP_WRAPPER 289 if (status_securenets == 0 || status_tcpwrap == 0) { 290 #else 291 if (status_securenets == 0) { 292 #endif 293 /* 294 * One of the following two events occurred: 295 * 296 * (1) The /var/yp/securenets exists and the remote host does not 297 * match any of the networks specified in it. 298 * (2) The hosts.allow file has denied access and TCP_WRAPPER is 299 * defined. 300 * 301 * In either case deny access. 302 */ 303 if (rqhost->sin_addr.s_addr != oldaddr) { 304 yp_error("connect from %s:%d to procedure %s refused", 305 inet_ntoa(rqhost->sin_addr), 306 ntohs(rqhost->sin_port), 307 yp_procedure); 308 oldaddr = rqhost->sin_addr.s_addr; 309 } 310 return(1); 311 } 312 return(0); 313 314 } 315 316 int 317 yp_validdomain(const char *domain) 318 { 319 struct stat statbuf; 320 char dompath[MAXPATHLEN + 2]; 321 322 if (domain == NULL || strstr(domain, "binding") || 323 !strcmp(domain, ".") || !strcmp(domain, "..") || 324 strchr(domain, '/') || strlen(domain) > YPMAXDOMAIN) 325 return(1); 326 327 snprintf(dompath, sizeof(dompath), "%s/%s", yp_dir, domain); 328 329 if (stat(dompath, &statbuf) < 0 || !S_ISDIR(statbuf.st_mode)) 330 return(1); 331 332 333 return(0); 334 } 335