1 /* 2 * This module implements a simple access control language that is based on 3 * host (or domain) names, NIS (host) netgroup names, IP addresses (or 4 * network numbers) and daemon process names. When a match is found the 5 * search is terminated, and depending on whether PROCESS_OPTIONS is defined, 6 * a list of options is executed or an optional shell command is executed. 7 * 8 * Host and user names are looked up on demand, provided that suitable endpoint 9 * information is available as sockaddr_in structures or TLI netbufs. As a 10 * side effect, the pattern matching process may change the contents of 11 * request structure fields. 12 * 13 * Diagnostics are reported through syslog(3). 14 * 15 * Compile with -DNETGROUP if your library provides support for netgroups. 16 * 17 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 18 * 19 * $FreeBSD: stable/10/contrib/tcp_wrappers/hosts_access.c 311814 2017-01-09 20:14:02Z dim $ 20 */ 21 22#ifndef lint 23static char sccsid[] = "@(#) hosts_access.c 1.21 97/02/12 02:13:22"; 24#endif 25 26/* System libraries. */ 27 28#include <sys/types.h> 29#ifdef INT32_T 30 typedef uint32_t u_int32_t; 31#endif 32#include <sys/param.h> 33#ifdef INET6 34#include <sys/socket.h> 35#endif 36#include <netinet/in.h> 37#include <arpa/inet.h> 38#include <stdio.h> 39#include <syslog.h> 40#include <ctype.h> 41#include <errno.h> 42#include <setjmp.h> 43#include <string.h> 44#ifdef INET6 45#include <netdb.h> 46#endif 47#include <stdlib.h> 48 49extern char *fgets(); 50extern int errno; 51 52#ifndef INADDR_NONE 53#define INADDR_NONE (-1) /* XXX should be 0xffffffff */ 54#endif 55 56/* Local stuff. */ 57 58#include "tcpd.h" 59 60/* Error handling. */ 61 62extern jmp_buf tcpd_buf; 63 64/* Delimiters for lists of daemons or clients. */ 65 66static char sep[] = ", \t\r\n"; 67 68/* Constants to be used in assignments only, not in comparisons... */ 69 70#define YES 1 71#define NO 0 72 73 /* 74 * These variables are globally visible so that they can be redirected in 75 * verification mode. 76 */ 77 78char *hosts_allow_table = HOSTS_ALLOW; 79char *hosts_deny_table = HOSTS_DENY; 80int hosts_access_verbose = 0; 81 82 /* 83 * In a long-running process, we are not at liberty to just go away. 84 */ 85 86int resident = (-1); /* -1, 0: unknown; +1: yes */ 87 88/* Forward declarations. */ 89 90static int table_match(); 91static int list_match(); 92static int server_match(); 93static int client_match(); 94static int host_match(); 95static int string_match(); 96static int masked_match(); 97#ifdef INET6 98static int masked_match4(); 99static int masked_match6(); 100#endif 101 102/* Size of logical line buffer. */ 103 104#define BUFLEN 2048 105 106/* definition to be used from workarounds.c */ 107#ifdef NETGROUP 108int yp_get_default_domain(char **); 109#endif 110 111/* hosts_access - host access control facility */ 112 113int hosts_access(request) 114struct request_info *request; 115{ 116 int verdict; 117 118 /* 119 * If the (daemon, client) pair is matched by an entry in the file 120 * /etc/hosts.allow, access is granted. Otherwise, if the (daemon, 121 * client) pair is matched by an entry in the file /etc/hosts.deny, 122 * access is denied. Otherwise, access is granted. A non-existent 123 * access-control file is treated as an empty file. 124 * 125 * After a rule has been matched, the optional language extensions may 126 * decide to grant or refuse service anyway. Or, while a rule is being 127 * processed, a serious error is found, and it seems better to play safe 128 * and deny service. All this is done by jumping back into the 129 * hosts_access() routine, bypassing the regular return from the 130 * table_match() function calls below. 131 */ 132 133 if (resident <= 0) 134 resident++; 135 verdict = setjmp(tcpd_buf); 136 if (verdict != 0) 137 return (verdict == AC_PERMIT); 138 if (table_match(hosts_allow_table, request)) 139 return (YES); 140 if (table_match(hosts_deny_table, request)) 141 return (NO); 142 return (YES); 143} 144 145/* table_match - match table entries with (daemon, client) pair */ 146 147static int table_match(table, request) 148char *table; 149struct request_info *request; 150{ 151 FILE *fp; 152 char sv_list[BUFLEN]; /* becomes list of daemons */ 153 char *cl_list; /* becomes list of clients */ 154 char *sh_cmd; /* becomes optional shell command */ 155 int match = NO; 156 struct tcpd_context saved_context; 157 char *cp; 158 159 saved_context = tcpd_context; /* stupid compilers */ 160 161 /* 162 * Between the fopen() and fclose() calls, avoid jumps that may cause 163 * file descriptor leaks. 164 */ 165 166 if ((fp = fopen(table, "r")) != 0) { 167 tcpd_context.file = table; 168 tcpd_context.line = 0; 169 while (match == NO && xgets(sv_list, sizeof(sv_list), fp) != 0) { 170 if (sv_list[strlen(sv_list) - 1] != '\n') { 171 tcpd_warn("missing newline or line too long"); 172 continue; 173 } 174 /* Ignore anything after unescaped # character */ 175 for (cp = strchr(sv_list, '#'); cp != NULL;) { 176 if (cp > sv_list && cp[-1] == '\\') { 177 cp = strchr(cp + 1, '#'); 178 continue; 179 } 180 *cp = '\0'; 181 break; 182 } 183 if (sv_list[strspn(sv_list, " \t\r\n")] == 0) 184 continue; 185 if ((cl_list = split_at(sv_list, ':')) == 0) { 186 tcpd_warn("missing \":\" separator"); 187 continue; 188 } 189 sh_cmd = split_at(cl_list, ':'); 190 match = list_match(sv_list, request, server_match) 191 && list_match(cl_list, request, client_match); 192 } 193 (void) fclose(fp); 194 } else if (errno != ENOENT) { 195 tcpd_warn("cannot open %s: %m", table); 196 } 197 if (match) { 198 if (hosts_access_verbose > 1) 199 syslog(LOG_DEBUG, "matched: %s line %d", 200 tcpd_context.file, tcpd_context.line); 201 if (sh_cmd) { 202#ifdef PROCESS_OPTIONS 203 process_options(sh_cmd, request); 204#else 205 char cmd[BUFSIZ]; 206 shell_cmd(percent_x(cmd, sizeof(cmd), sh_cmd, request)); 207#endif 208 } 209 } 210 tcpd_context = saved_context; 211 return (match); 212} 213 214/* list_match - match a request against a list of patterns with exceptions */ 215 216static int list_match(list, request, match_fn) 217char *list; 218struct request_info *request; 219int (*match_fn) (); 220{ 221 char *tok; 222 223 /* 224 * Process tokens one at a time. We have exhausted all possible matches 225 * when we reach an "EXCEPT" token or the end of the list. If we do find 226 * a match, look for an "EXCEPT" list and recurse to determine whether 227 * the match is affected by any exceptions. 228 */ 229 230 for (tok = strtok(list, sep); tok != 0; tok = strtok((char *) 0, sep)) { 231 if (STR_EQ(tok, "EXCEPT")) /* EXCEPT: give up */ 232 return (NO); 233 if (match_fn(tok, request)) { /* YES: look for exceptions */ 234 while ((tok = strtok((char *) 0, sep)) && STR_NE(tok, "EXCEPT")) 235 /* VOID */ ; 236 return (tok == 0 || list_match((char *) 0, request, match_fn) == 0); 237 } 238 } 239 return (NO); 240} 241 242/* server_match - match server information */ 243 244static int server_match(tok, request) 245char *tok; 246struct request_info *request; 247{ 248 char *host; 249 250 if ((host = split_at(tok + 1, '@')) == 0) { /* plain daemon */ 251 return (string_match(tok, eval_daemon(request))); 252 } else { /* daemon@host */ 253 return (string_match(tok, eval_daemon(request)) 254 && host_match(host, request->server)); 255 } 256} 257 258/* client_match - match client information */ 259 260static int client_match(tok, request) 261char *tok; 262struct request_info *request; 263{ 264 char *host; 265 266 if ((host = split_at(tok + 1, '@')) == 0) { /* plain host */ 267 return (host_match(tok, request->client)); 268 } else { /* user@host */ 269 return (host_match(host, request->client) 270 && string_match(tok, eval_user(request))); 271 } 272} 273 274/* hostfile_match - look up host patterns from file */ 275 276static int hostfile_match(path, host) 277char *path; 278struct host_info *host; 279{ 280 char tok[BUFSIZ]; 281 int match = NO; 282 FILE *fp; 283 284 if ((fp = fopen(path, "r")) != 0) { 285 while (fscanf(fp, "%s", tok) == 1 && !(match = host_match(tok, host))) 286 /* void */ ; 287 fclose(fp); 288 } else if (errno != ENOENT) { 289 tcpd_warn("open %s: %m", path); 290 } 291 return (match); 292} 293 294/* host_match - match host name and/or address against pattern */ 295 296static int host_match(tok, host) 297char *tok; 298struct host_info *host; 299{ 300 char *mask; 301 302 /* 303 * This code looks a little hairy because we want to avoid unnecessary 304 * hostname lookups. 305 * 306 * The KNOWN pattern requires that both address AND name be known; some 307 * patterns are specific to host names or to host addresses; all other 308 * patterns are satisfied when either the address OR the name match. 309 */ 310 311 if (tok[0] == '@') { /* netgroup: look it up */ 312#ifdef NETGROUP 313 static char *mydomain = 0; 314 if (mydomain == 0) 315 yp_get_default_domain(&mydomain); 316 return (innetgr(tok + 1, eval_hostname(host), (char *) 0, mydomain)); 317#else 318 tcpd_warn("netgroup support is disabled"); /* not tcpd_jump() */ 319 return (NO); 320#endif 321 } else if (tok[0] == '/') { /* /file hack */ 322 return (hostfile_match(tok, host)); 323 } else if (STR_EQ(tok, "KNOWN")) { /* check address and name */ 324 char *name = eval_hostname(host); 325 return (STR_NE(eval_hostaddr(host), unknown) && HOSTNAME_KNOWN(name)); 326 } else if (STR_EQ(tok, "LOCAL")) { /* local: no dots in name */ 327 char *name = eval_hostname(host); 328 return (strchr(name, '.') == 0 && HOSTNAME_KNOWN(name)); 329 } else if ((mask = split_at(tok, '/')) != 0) { /* net/mask */ 330 return (masked_match(tok, mask, eval_hostaddr(host))); 331 } else { /* anything else */ 332 return (string_match(tok, eval_hostaddr(host)) 333 || (NOT_INADDR(tok) && string_match(tok, eval_hostname(host)))); 334 } 335} 336 337/* string_match - match string against pattern */ 338 339static int string_match(tok, string) 340char *tok; 341char *string; 342{ 343 int n; 344 345#ifdef INET6 346 /* convert IPv4 mapped IPv6 address to IPv4 address */ 347 if (STRN_EQ(string, "::ffff:", 7) 348 && dot_quad_addr(string + 7) != INADDR_NONE) { 349 string += 7; 350 } 351#endif 352 if (tok[0] == '.') { /* suffix */ 353 n = strlen(string) - strlen(tok); 354 return (n > 0 && STR_EQ(tok, string + n)); 355 } else if (STR_EQ(tok, "ALL")) { /* all: match any */ 356 return (YES); 357 } else if (STR_EQ(tok, "KNOWN")) { /* not unknown */ 358 return (STR_NE(string, unknown)); 359 } else if (tok[(n = strlen(tok)) - 1] == '.') { /* prefix */ 360 return (STRN_EQ(tok, string, n)); 361 } else { /* exact match */ 362#ifdef INET6 363 struct addrinfo hints, *res; 364 struct sockaddr_in6 pat, addr; 365 int len, ret; 366 char ch; 367 368 len = strlen(tok); 369 if (*tok == '[' && tok[len - 1] == ']') { 370 ch = tok[len - 1]; 371 tok[len - 1] = '\0'; 372 memset(&hints, 0, sizeof(hints)); 373 hints.ai_family = AF_INET6; 374 hints.ai_socktype = SOCK_STREAM; 375 hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST; 376 if ((ret = getaddrinfo(tok + 1, NULL, &hints, &res)) == 0) { 377 memcpy(&pat, res->ai_addr, sizeof(pat)); 378 freeaddrinfo(res); 379 } 380 tok[len - 1] = ch; 381 if (ret != 0 || getaddrinfo(string, NULL, &hints, &res) != 0) 382 return NO; 383 memcpy(&addr, res->ai_addr, sizeof(addr)); 384 freeaddrinfo(res); 385 if (pat.sin6_scope_id != 0 && 386 addr.sin6_scope_id != pat.sin6_scope_id) 387 return NO; 388 return (!memcmp(&pat.sin6_addr, &addr.sin6_addr, 389 sizeof(struct in6_addr))); 390 return (ret); 391 } 392#endif 393 return (STR_EQ(tok, string)); 394 } 395} 396 397/* masked_match - match address against netnumber/netmask */ 398 399#ifdef INET6 400static int masked_match(net_tok, mask_tok, string) 401char *net_tok; 402char *mask_tok; 403char *string; 404{ 405 return (masked_match4(net_tok, mask_tok, string) || 406 masked_match6(net_tok, mask_tok, string)); 407} 408 409static int masked_match4(net_tok, mask_tok, string) 410#else 411static int masked_match(net_tok, mask_tok, string) 412#endif 413char *net_tok; 414char *mask_tok; 415char *string; 416{ 417#ifdef INET6 418 u_int32_t net; 419 u_int32_t mask; 420 u_int32_t addr; 421#else 422 unsigned long net; 423 unsigned long mask; 424 unsigned long addr; 425#endif 426 427 /* 428 * Disallow forms other than dotted quad: the treatment that inet_addr() 429 * gives to forms with less than four components is inconsistent with the 430 * access control language. John P. Rouillard <rouilj@cs.umb.edu>. 431 */ 432 433 if ((addr = dot_quad_addr(string)) == INADDR_NONE) 434 return (NO); 435 if ((net = dot_quad_addr(net_tok)) == INADDR_NONE 436 || (mask = dot_quad_addr(mask_tok)) == INADDR_NONE) { 437#ifndef INET6 438 tcpd_warn("bad net/mask expression: %s/%s", net_tok, mask_tok); 439#endif 440 return (NO); /* not tcpd_jump() */ 441 } 442 return ((addr & mask) == net); 443} 444 445#ifdef INET6 446static int masked_match6(net_tok, mask_tok, string) 447char *net_tok; 448char *mask_tok; 449char *string; 450{ 451 struct addrinfo hints, *res; 452 struct sockaddr_in6 net, addr; 453 u_int32_t mask; 454 int len, mask_len, i = 0; 455 char ch; 456 457 memset(&hints, 0, sizeof(hints)); 458 hints.ai_family = AF_INET6; 459 hints.ai_socktype = SOCK_STREAM; 460 hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST; 461 if (getaddrinfo(string, NULL, &hints, &res) != 0) 462 return NO; 463 memcpy(&addr, res->ai_addr, sizeof(addr)); 464 freeaddrinfo(res); 465 466 if (IN6_IS_ADDR_V4MAPPED(&addr.sin6_addr)) { 467 if ((*(u_int32_t *)&net.sin6_addr.s6_addr[12] = dot_quad_addr(net_tok)) == INADDR_NONE 468 || (mask = dot_quad_addr(mask_tok)) == INADDR_NONE) 469 return (NO); 470 return ((*(u_int32_t *)&addr.sin6_addr.s6_addr[12] & mask) == *(u_int32_t *)&net.sin6_addr.s6_addr[12]); 471 } 472 473 /* match IPv6 address against netnumber/prefixlen */ 474 len = strlen(net_tok); 475 if (*net_tok != '[' || net_tok[len - 1] != ']') 476 return NO; 477 ch = net_tok[len - 1]; 478 net_tok[len - 1] = '\0'; 479 if (getaddrinfo(net_tok + 1, NULL, &hints, &res) != 0) { 480 net_tok[len - 1] = ch; 481 return NO; 482 } 483 memcpy(&net, res->ai_addr, sizeof(net)); 484 freeaddrinfo(res); 485 net_tok[len - 1] = ch; 486 if ((mask_len = atoi(mask_tok)) < 0 || mask_len > 128) 487 return NO; 488 489 if (net.sin6_scope_id != 0 && addr.sin6_scope_id != net.sin6_scope_id) 490 return NO; 491 while (mask_len > 0) { 492 if (mask_len < 32) { 493 mask = htonl(~(0xffffffff >> mask_len)); 494 if ((*(u_int32_t *)&addr.sin6_addr.s6_addr[i] & mask) != (*(u_int32_t *)&net.sin6_addr.s6_addr[i] & mask)) 495 return NO; 496 break; 497 } 498 if (*(u_int32_t *)&addr.sin6_addr.s6_addr[i] != *(u_int32_t *)&net.sin6_addr.s6_addr[i]) 499 return NO; 500 i += 4; 501 mask_len -= 32; 502 } 503 return YES; 504} 505#endif /* INET6 */ 506