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: head/contrib/tcp_wrappers/hosts_access.c 51495 1999-09-21 09:09:57Z sheldonh $
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#include <sys/param.h>
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <stdio.h>
33#include <syslog.h>
34#include <ctype.h>
35#include <errno.h>
36#include <setjmp.h>
37#include <string.h>
38
39extern char *fgets();
40extern int errno;
41
42#ifndef INADDR_NONE
43#define INADDR_NONE (-1) /* XXX should be 0xffffffff */
44#endif
45
46/* Local stuff. */
47
48#include "tcpd.h"
49
50/* Error handling. */
51
52extern jmp_buf tcpd_buf;
53
54/* Delimiters for lists of daemons or clients. */
55
56static char sep[] = ", \t\r\n";
57
58/* Constants to be used in assignments only, not in comparisons... */
59
60#define YES 1
61#define NO 0
62
63 /*
64 * These variables are globally visible so that they can be redirected in
65 * verification mode.
66 */
67
68char *hosts_allow_table = HOSTS_ALLOW;
69char *hosts_deny_table = HOSTS_DENY;
70int hosts_access_verbose = 0;
71
72 /*
73 * In a long-running process, we are not at liberty to just go away.
74 */
75
76int resident = (-1); /* -1, 0: unknown; +1: yes */
77
78/* Forward declarations. */
79
80static int table_match();
81static int list_match();
82static int server_match();
83static int client_match();
84static int host_match();
85static int string_match();
86static int masked_match();
87
88/* Size of logical line buffer. */
89
90#define BUFLEN 2048
91
92/* hosts_access - host access control facility */
93
94int hosts_access(request)
95struct request_info *request;
96{
97 int verdict;
98
99 /*
100 * If the (daemon, client) pair is matched by an entry in the file
101 * /etc/hosts.allow, access is granted. Otherwise, if the (daemon,
102 * client) pair is matched by an entry in the file /etc/hosts.deny,
103 * access is denied. Otherwise, access is granted. A non-existent
104 * access-control file is treated as an empty file.
105 *
106 * After a rule has been matched, the optional language extensions may
107 * decide to grant or refuse service anyway. Or, while a rule is being
108 * processed, a serious error is found, and it seems better to play safe
109 * and deny service. All this is done by jumping back into the
110 * hosts_access() routine, bypassing the regular return from the
111 * table_match() function calls below.
112 */
113
114 if (resident <= 0)
115 resident++;
116 verdict = setjmp(tcpd_buf);
117 if (verdict != 0)
118 return (verdict == AC_PERMIT);
119 if (table_match(hosts_allow_table, request))
120 return (YES);
121 if (table_match(hosts_deny_table, request))
122 return (NO);
123 return (YES);
124}
125
126/* table_match - match table entries with (daemon, client) pair */
127
128static int table_match(table, request)
129char *table;
130struct request_info *request;
131{
132 FILE *fp;
133 char sv_list[BUFLEN]; /* becomes list of daemons */
134 char *cl_list; /* becomes list of clients */
135 char *sh_cmd; /* becomes optional shell command */
136 int match = NO;
137 struct tcpd_context saved_context;
138
139 saved_context = tcpd_context; /* stupid compilers */
140
141 /*
142 * Between the fopen() and fclose() calls, avoid jumps that may cause
143 * file descriptor leaks.
144 */
145
146 if ((fp = fopen(table, "r")) != 0) {
147 tcpd_context.file = table;
148 tcpd_context.line = 0;
149 while (match == NO && xgets(sv_list, sizeof(sv_list), fp) != 0) {
150 if (sv_list[strlen(sv_list) - 1] != '\n') {
151 tcpd_warn("missing newline or line too long");
152 continue;
153 }
154 if (sv_list[0] == '#' || sv_list[strspn(sv_list, " \t\r\n")] == 0)
155 continue;
156 if ((cl_list = split_at(sv_list, ':')) == 0) {
157 tcpd_warn("missing \":\" separator");
158 continue;
159 }
160 sh_cmd = split_at(cl_list, ':');
161 match = list_match(sv_list, request, server_match)
162 && list_match(cl_list, request, client_match);
163 }
164 (void) fclose(fp);
165 } else if (errno != ENOENT) {
166 tcpd_warn("cannot open %s: %m", table);
167 }
168 if (match) {
169 if (hosts_access_verbose > 1)
170 syslog(LOG_DEBUG, "matched: %s line %d",
171 tcpd_context.file, tcpd_context.line);
172 if (sh_cmd) {
173#ifdef PROCESS_OPTIONS
174 process_options(sh_cmd, request);
175#else
176 char cmd[BUFSIZ];
177 shell_cmd(percent_x(cmd, sizeof(cmd), sh_cmd, request));
178#endif
179 }
180 }
181 tcpd_context = saved_context;
182 return (match);
183}
184
185/* list_match - match a request against a list of patterns with exceptions */
186
187static int list_match(list, request, match_fn)
188char *list;
189struct request_info *request;
190int (*match_fn) ();
191{
192 char *tok;
193
194 /*
195 * Process tokens one at a time. We have exhausted all possible matches
196 * when we reach an "EXCEPT" token or the end of the list. If we do find
197 * a match, look for an "EXCEPT" list and recurse to determine whether
198 * the match is affected by any exceptions.
199 */
200
201 for (tok = strtok(list, sep); tok != 0; tok = strtok((char *) 0, sep)) {
202 if (STR_EQ(tok, "EXCEPT")) /* EXCEPT: give up */
203 return (NO);
204 if (match_fn(tok, request)) { /* YES: look for exceptions */
205 while ((tok = strtok((char *) 0, sep)) && STR_NE(tok, "EXCEPT"))
206 /* VOID */ ;
207 return (tok == 0 || list_match((char *) 0, request, match_fn) == 0);
208 }
209 }
210 return (NO);
211}
212
213/* server_match - match server information */
214
215static int server_match(tok, request)
216char *tok;
217struct request_info *request;
218{
219 char *host;
220
221 if ((host = split_at(tok + 1, '@')) == 0) { /* plain daemon */
222 return (string_match(tok, eval_daemon(request)));
223 } else { /* daemon@host */
224 return (string_match(tok, eval_daemon(request))
225 && host_match(host, request->server));
226 }
227}
228
229/* client_match - match client information */
230
231static int client_match(tok, request)
232char *tok;
233struct request_info *request;
234{
235 char *host;
236
237 if ((host = split_at(tok + 1, '@')) == 0) { /* plain host */
238 return (host_match(tok, request->client));
239 } else { /* user@host */
240 return (host_match(host, request->client)
241 && string_match(tok, eval_user(request)));
242 }
243}
244
245/* hostfile_match - look up host patterns from file */
246
247static int hostfile_match(path, host)
248char *path;
249struct hosts_info *host;
250{
251 char tok[BUFSIZ];
252 int match = NO;
253 FILE *fp;
254
255 if ((fp = fopen(path, "r")) != 0) {
256 while (fscanf(fp, "%s", tok) == 1 && !(match = host_match(tok, host)))
257 /* void */ ;
258 fclose(fp);
259 } else if (errno != ENOENT) {
260 tcpd_warn("open %s: %m", path);
261 }
262 return (match);
263}
264
265/* host_match - match host name and/or address against pattern */
266
267static int host_match(tok, host)
268char *tok;
269struct host_info *host;
270{
271 char *mask;
272
273 /*
274 * This code looks a little hairy because we want to avoid unnecessary
275 * hostname lookups.
276 *
277 * The KNOWN pattern requires that both address AND name be known; some
278 * patterns are specific to host names or to host addresses; all other
279 * patterns are satisfied when either the address OR the name match.
280 */
281
282 if (tok[0] == '@') { /* netgroup: look it up */
283#ifdef NETGROUP
284 static char *mydomain = 0;
285 if (mydomain == 0)
286 yp_get_default_domain(&mydomain);
287 return (innetgr(tok + 1, eval_hostname(host), (char *) 0, mydomain));
288#else
289 tcpd_warn("netgroup support is disabled"); /* not tcpd_jump() */
290 return (NO);
291#endif
292 } else if (tok[0] == '/') { /* /file hack */
293 return (hostfile_match(tok, host));
294 } else if (STR_EQ(tok, "KNOWN")) { /* check address and name */
295 char *name = eval_hostname(host);
296 return (STR_NE(eval_hostaddr(host), unknown) && HOSTNAME_KNOWN(name));
297 } else if (STR_EQ(tok, "LOCAL")) { /* local: no dots in name */
298 char *name = eval_hostname(host);
299 return (strchr(name, '.') == 0 && HOSTNAME_KNOWN(name));
300 } else if ((mask = split_at(tok, '/')) != 0) { /* net/mask */
301 return (masked_match(tok, mask, eval_hostaddr(host)));
302 } else { /* anything else */
303 return (string_match(tok, eval_hostaddr(host))
304 || (NOT_INADDR(tok) && string_match(tok, eval_hostname(host))));
305 }
306}
307
308/* string_match - match string against pattern */
309
310static int string_match(tok, string)
311char *tok;
312char *string;
313{
314 int n;
315
316 if (tok[0] == '.') { /* suffix */
317 n = strlen(string) - strlen(tok);
318 return (n > 0 && STR_EQ(tok, string + n));
319 } else if (STR_EQ(tok, "ALL")) { /* all: match any */
320 return (YES);
321 } else if (STR_EQ(tok, "KNOWN")) { /* not unknown */
322 return (STR_NE(string, unknown));
323 } else if (tok[(n = strlen(tok)) - 1] == '.') { /* prefix */
324 return (STRN_EQ(tok, string, n));
325 } else { /* exact match */
326 return (STR_EQ(tok, string));
327 }
328}
329
330/* masked_match - match address against netnumber/netmask */
331
332static int masked_match(net_tok, mask_tok, string)
333char *net_tok;
334char *mask_tok;
335char *string;
336{
337 unsigned long net;
338 unsigned long mask;
339 unsigned long addr;
340
341 /*
342 * Disallow forms other than dotted quad: the treatment that inet_addr()
343 * gives to forms with less than four components is inconsistent with the
344 * access control language. John P. Rouillard <rouilj@cs.umb.edu>.
345 */
346
347 if ((addr = dot_quad_addr(string)) == INADDR_NONE)
348 return (NO);
349 if ((net = dot_quad_addr(net_tok)) == INADDR_NONE
350 || (mask = dot_quad_addr(mask_tok)) == INADDR_NONE) {
351 tcpd_warn("bad net/mask expression: %s/%s", net_tok, mask_tok);
352 return (NO); /* not tcpd_jump() */
353 }
354 return ((addr & mask) == net);
355}
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: head/contrib/tcp_wrappers/hosts_access.c 51495 1999-09-21 09:09:57Z sheldonh $
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#include <sys/param.h>
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <stdio.h>
33#include <syslog.h>
34#include <ctype.h>
35#include <errno.h>
36#include <setjmp.h>
37#include <string.h>
38
39extern char *fgets();
40extern int errno;
41
42#ifndef INADDR_NONE
43#define INADDR_NONE (-1) /* XXX should be 0xffffffff */
44#endif
45
46/* Local stuff. */
47
48#include "tcpd.h"
49
50/* Error handling. */
51
52extern jmp_buf tcpd_buf;
53
54/* Delimiters for lists of daemons or clients. */
55
56static char sep[] = ", \t\r\n";
57
58/* Constants to be used in assignments only, not in comparisons... */
59
60#define YES 1
61#define NO 0
62
63 /*
64 * These variables are globally visible so that they can be redirected in
65 * verification mode.
66 */
67
68char *hosts_allow_table = HOSTS_ALLOW;
69char *hosts_deny_table = HOSTS_DENY;
70int hosts_access_verbose = 0;
71
72 /*
73 * In a long-running process, we are not at liberty to just go away.
74 */
75
76int resident = (-1); /* -1, 0: unknown; +1: yes */
77
78/* Forward declarations. */
79
80static int table_match();
81static int list_match();
82static int server_match();
83static int client_match();
84static int host_match();
85static int string_match();
86static int masked_match();
87
88/* Size of logical line buffer. */
89
90#define BUFLEN 2048
91
92/* hosts_access - host access control facility */
93
94int hosts_access(request)
95struct request_info *request;
96{
97 int verdict;
98
99 /*
100 * If the (daemon, client) pair is matched by an entry in the file
101 * /etc/hosts.allow, access is granted. Otherwise, if the (daemon,
102 * client) pair is matched by an entry in the file /etc/hosts.deny,
103 * access is denied. Otherwise, access is granted. A non-existent
104 * access-control file is treated as an empty file.
105 *
106 * After a rule has been matched, the optional language extensions may
107 * decide to grant or refuse service anyway. Or, while a rule is being
108 * processed, a serious error is found, and it seems better to play safe
109 * and deny service. All this is done by jumping back into the
110 * hosts_access() routine, bypassing the regular return from the
111 * table_match() function calls below.
112 */
113
114 if (resident <= 0)
115 resident++;
116 verdict = setjmp(tcpd_buf);
117 if (verdict != 0)
118 return (verdict == AC_PERMIT);
119 if (table_match(hosts_allow_table, request))
120 return (YES);
121 if (table_match(hosts_deny_table, request))
122 return (NO);
123 return (YES);
124}
125
126/* table_match - match table entries with (daemon, client) pair */
127
128static int table_match(table, request)
129char *table;
130struct request_info *request;
131{
132 FILE *fp;
133 char sv_list[BUFLEN]; /* becomes list of daemons */
134 char *cl_list; /* becomes list of clients */
135 char *sh_cmd; /* becomes optional shell command */
136 int match = NO;
137 struct tcpd_context saved_context;
138
139 saved_context = tcpd_context; /* stupid compilers */
140
141 /*
142 * Between the fopen() and fclose() calls, avoid jumps that may cause
143 * file descriptor leaks.
144 */
145
146 if ((fp = fopen(table, "r")) != 0) {
147 tcpd_context.file = table;
148 tcpd_context.line = 0;
149 while (match == NO && xgets(sv_list, sizeof(sv_list), fp) != 0) {
150 if (sv_list[strlen(sv_list) - 1] != '\n') {
151 tcpd_warn("missing newline or line too long");
152 continue;
153 }
154 if (sv_list[0] == '#' || sv_list[strspn(sv_list, " \t\r\n")] == 0)
155 continue;
156 if ((cl_list = split_at(sv_list, ':')) == 0) {
157 tcpd_warn("missing \":\" separator");
158 continue;
159 }
160 sh_cmd = split_at(cl_list, ':');
161 match = list_match(sv_list, request, server_match)
162 && list_match(cl_list, request, client_match);
163 }
164 (void) fclose(fp);
165 } else if (errno != ENOENT) {
166 tcpd_warn("cannot open %s: %m", table);
167 }
168 if (match) {
169 if (hosts_access_verbose > 1)
170 syslog(LOG_DEBUG, "matched: %s line %d",
171 tcpd_context.file, tcpd_context.line);
172 if (sh_cmd) {
173#ifdef PROCESS_OPTIONS
174 process_options(sh_cmd, request);
175#else
176 char cmd[BUFSIZ];
177 shell_cmd(percent_x(cmd, sizeof(cmd), sh_cmd, request));
178#endif
179 }
180 }
181 tcpd_context = saved_context;
182 return (match);
183}
184
185/* list_match - match a request against a list of patterns with exceptions */
186
187static int list_match(list, request, match_fn)
188char *list;
189struct request_info *request;
190int (*match_fn) ();
191{
192 char *tok;
193
194 /*
195 * Process tokens one at a time. We have exhausted all possible matches
196 * when we reach an "EXCEPT" token or the end of the list. If we do find
197 * a match, look for an "EXCEPT" list and recurse to determine whether
198 * the match is affected by any exceptions.
199 */
200
201 for (tok = strtok(list, sep); tok != 0; tok = strtok((char *) 0, sep)) {
202 if (STR_EQ(tok, "EXCEPT")) /* EXCEPT: give up */
203 return (NO);
204 if (match_fn(tok, request)) { /* YES: look for exceptions */
205 while ((tok = strtok((char *) 0, sep)) && STR_NE(tok, "EXCEPT"))
206 /* VOID */ ;
207 return (tok == 0 || list_match((char *) 0, request, match_fn) == 0);
208 }
209 }
210 return (NO);
211}
212
213/* server_match - match server information */
214
215static int server_match(tok, request)
216char *tok;
217struct request_info *request;
218{
219 char *host;
220
221 if ((host = split_at(tok + 1, '@')) == 0) { /* plain daemon */
222 return (string_match(tok, eval_daemon(request)));
223 } else { /* daemon@host */
224 return (string_match(tok, eval_daemon(request))
225 && host_match(host, request->server));
226 }
227}
228
229/* client_match - match client information */
230
231static int client_match(tok, request)
232char *tok;
233struct request_info *request;
234{
235 char *host;
236
237 if ((host = split_at(tok + 1, '@')) == 0) { /* plain host */
238 return (host_match(tok, request->client));
239 } else { /* user@host */
240 return (host_match(host, request->client)
241 && string_match(tok, eval_user(request)));
242 }
243}
244
245/* hostfile_match - look up host patterns from file */
246
247static int hostfile_match(path, host)
248char *path;
249struct hosts_info *host;
250{
251 char tok[BUFSIZ];
252 int match = NO;
253 FILE *fp;
254
255 if ((fp = fopen(path, "r")) != 0) {
256 while (fscanf(fp, "%s", tok) == 1 && !(match = host_match(tok, host)))
257 /* void */ ;
258 fclose(fp);
259 } else if (errno != ENOENT) {
260 tcpd_warn("open %s: %m", path);
261 }
262 return (match);
263}
264
265/* host_match - match host name and/or address against pattern */
266
267static int host_match(tok, host)
268char *tok;
269struct host_info *host;
270{
271 char *mask;
272
273 /*
274 * This code looks a little hairy because we want to avoid unnecessary
275 * hostname lookups.
276 *
277 * The KNOWN pattern requires that both address AND name be known; some
278 * patterns are specific to host names or to host addresses; all other
279 * patterns are satisfied when either the address OR the name match.
280 */
281
282 if (tok[0] == '@') { /* netgroup: look it up */
283#ifdef NETGROUP
284 static char *mydomain = 0;
285 if (mydomain == 0)
286 yp_get_default_domain(&mydomain);
287 return (innetgr(tok + 1, eval_hostname(host), (char *) 0, mydomain));
288#else
289 tcpd_warn("netgroup support is disabled"); /* not tcpd_jump() */
290 return (NO);
291#endif
292 } else if (tok[0] == '/') { /* /file hack */
293 return (hostfile_match(tok, host));
294 } else if (STR_EQ(tok, "KNOWN")) { /* check address and name */
295 char *name = eval_hostname(host);
296 return (STR_NE(eval_hostaddr(host), unknown) && HOSTNAME_KNOWN(name));
297 } else if (STR_EQ(tok, "LOCAL")) { /* local: no dots in name */
298 char *name = eval_hostname(host);
299 return (strchr(name, '.') == 0 && HOSTNAME_KNOWN(name));
300 } else if ((mask = split_at(tok, '/')) != 0) { /* net/mask */
301 return (masked_match(tok, mask, eval_hostaddr(host)));
302 } else { /* anything else */
303 return (string_match(tok, eval_hostaddr(host))
304 || (NOT_INADDR(tok) && string_match(tok, eval_hostname(host))));
305 }
306}
307
308/* string_match - match string against pattern */
309
310static int string_match(tok, string)
311char *tok;
312char *string;
313{
314 int n;
315
316 if (tok[0] == '.') { /* suffix */
317 n = strlen(string) - strlen(tok);
318 return (n > 0 && STR_EQ(tok, string + n));
319 } else if (STR_EQ(tok, "ALL")) { /* all: match any */
320 return (YES);
321 } else if (STR_EQ(tok, "KNOWN")) { /* not unknown */
322 return (STR_NE(string, unknown));
323 } else if (tok[(n = strlen(tok)) - 1] == '.') { /* prefix */
324 return (STRN_EQ(tok, string, n));
325 } else { /* exact match */
326 return (STR_EQ(tok, string));
327 }
328}
329
330/* masked_match - match address against netnumber/netmask */
331
332static int masked_match(net_tok, mask_tok, string)
333char *net_tok;
334char *mask_tok;
335char *string;
336{
337 unsigned long net;
338 unsigned long mask;
339 unsigned long addr;
340
341 /*
342 * Disallow forms other than dotted quad: the treatment that inet_addr()
343 * gives to forms with less than four components is inconsistent with the
344 * access control language. John P. Rouillard <rouilj@cs.umb.edu>.
345 */
346
347 if ((addr = dot_quad_addr(string)) == INADDR_NONE)
348 return (NO);
349 if ((net = dot_quad_addr(net_tok)) == INADDR_NONE
350 || (mask = dot_quad_addr(mask_tok)) == INADDR_NONE) {
351 tcpd_warn("bad net/mask expression: %s/%s", net_tok, mask_tok);
352 return (NO); /* not tcpd_jump() */
353 }
354 return ((addr & mask) == net);
355}