1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
|
/*
* General skeleton for adding options to the access control language. The
* features offered by this module are documented in the hosts_options(5)
* manual page (source file: hosts_options.5, "nroff -man" format).
*
* Notes and warnings for those who want to add features:
*
* In case of errors, abort options processing and deny access. There are too
* many irreversible side effects to make error recovery feasible. For
* example, it makes no sense to continue after we have already changed the
* userid.
*
* In case of errors, do not terminate the process: the routines might be
* called from a long-running daemon that should run forever. Instead, call
* tcpd_jump() which does a non-local goto back into the hosts_access()
* routine.
*
* In case of severe errors, use clean_exit() instead of directly calling
* exit(), or the inetd may loop on an UDP request.
*
* In verification mode (for example, with the "tcpdmatch" command) the
* "dry_run" flag is set. In this mode, an option function should just "say"
* what it is going to do instead of really doing it.
*
* Some option functions do not return (for example, the twist option passes
* control to another program). In verification mode (dry_run flag is set)
* such options should clear the "dry_run" flag to inform the caller of this
* course of action.
*
* $FreeBSD$
*/
#ifndef lint
static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
#endif
/* System libraries. */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#define SYSLOG_NAMES
#include <syslog.h>
#include <pwd.h>
#include <grp.h>
#include <ctype.h>
#include <setjmp.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#ifndef MAXPATHNAMELEN
#define MAXPATHNAMELEN BUFSIZ
#endif
/* Local stuff. */
#include "tcpd.h"
/* Options runtime support. */
int dry_run = 0; /* flag set in verification mode */
extern jmp_buf tcpd_buf; /* tcpd_jump() support */
/* Options parser support. */
static char whitespace_eq[] = "= \t\r\n";
#define whitespace (whitespace_eq + 1)
static char *get_field(); /* chew :-delimited field off string */
static char *chop_string(); /* strip leading and trailing blanks */
/* List of functions that implement the options. Add yours here. */
static void user_option(); /* execute "user name.group" option */
static void group_option(); /* execute "group name" option */
static void umask_option(); /* execute "umask mask" option */
static void linger_option(); /* execute "linger time" option */
static void keepalive_option(); /* execute "keepalive" option */
static void spawn_option(); /* execute "spawn command" option */
static void twist_option(); /* execute "twist command" option */
static void rfc931_option(); /* execute "rfc931" option */
static void setenv_option(); /* execute "setenv name value" */
static void nice_option(); /* execute "nice" option */
static void severity_option(); /* execute "severity value" */
static void allow_option(); /* execute "allow" option */
static void deny_option(); /* execute "deny" option */
static void banners_option(); /* execute "banners path" option */
/* Structure of the options table. */
struct option {
char *name; /* keyword name, case is ignored */
void (*func) (); /* function that does the real work */
int flags; /* see below... */
};
#define NEED_ARG (1<<1) /* option requires argument */
#define USE_LAST (1<<2) /* option must be last */
#define OPT_ARG (1<<3) /* option has optional argument */
#define EXPAND_ARG (1<<4) /* do %x expansion on argument */
#define need_arg(o) ((o)->flags & NEED_ARG)
#define opt_arg(o) ((o)->flags & OPT_ARG)
#define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG))
#define use_last(o) ((o)->flags & USE_LAST)
#define expand_arg(o) ((o)->flags & EXPAND_ARG)
/* List of known keywords. Add yours here. */
static struct option option_table[] = {
"user", user_option, NEED_ARG,
"group", group_option, NEED_ARG,
"umask", umask_option, NEED_ARG,
"linger", linger_option, NEED_ARG,
"keepalive", keepalive_option, 0,
"spawn", spawn_option, NEED_ARG | EXPAND_ARG,
"twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
"rfc931", rfc931_option, OPT_ARG,
"setenv", setenv_option, NEED_ARG | EXPAND_ARG,
"nice", nice_option, OPT_ARG,
"severity", severity_option, NEED_ARG,
"allow", allow_option, USE_LAST,
"deny", deny_option, USE_LAST,
"banners", banners_option, NEED_ARG,
0,
};
/* process_options - process access control options */
void process_options(options, request)
char *options;
struct request_info *request;
{
char *key;
char *value;
char *curr_opt;
char *next_opt;
struct option *op;
char bf[BUFSIZ];
for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
next_opt = get_field((char *) 0);
/*
* Separate the option into name and value parts. For backwards
* compatibility we ignore exactly one '=' between name and value.
*/
curr_opt = chop_string(curr_opt);
if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
if (*value != '=') {
*value++ = 0;
value += strspn(value, whitespace);
}
if (*value == '=') {
*value++ = 0;
value += strspn(value, whitespace);
}
}
if (*value == 0)
value = 0;
key = curr_opt;
/*
* Disallow missing option names (and empty option fields).
*/
if (*key == 0)
tcpd_jump("missing option name");
/*
* Lookup the option-specific info and do some common error checks.
* Delegate option-specific processing to the specific functions.
*/
for (op = option_table; op->name && STR_NE(op->name, key); op++)
/* VOID */ ;
if (op->name == 0)
tcpd_jump("bad option name: \"%s\"", key);
if (!value && need_arg(op))
tcpd_jump("option \"%s\" requires value", key);
if (value && !permit_arg(op))
tcpd_jump("option \"%s\" requires no value", key);
if (next_opt && use_last(op))
tcpd_jump("option \"%s\" must be at end", key);
if (value && expand_arg(op))
value = chop_string(percent_x(bf, sizeof(bf), value, request));
if (hosts_access_verbose)
syslog(LOG_DEBUG, "option: %s %s", key, value ? value : "");
(*(op->func)) (value, request);
}
}
/* allow_option - grant access */
/* ARGSUSED */
static void allow_option(value, request)
char *value;
struct request_info *request;
{
longjmp(tcpd_buf, AC_PERMIT);
}
/* deny_option - deny access */
/* ARGSUSED */
static void deny_option(value, request)
char *value;
struct request_info *request;
{
longjmp(tcpd_buf, AC_DENY);
}
/* banners_option - expand %<char>, terminate each line with CRLF */
static void banners_option(value, request)
char *value;
struct request_info *request;
{
char path[MAXPATHNAMELEN];
char ibuf[BUFSIZ];
char obuf[2 * BUFSIZ];
struct stat st;
int ch;
FILE *fp;
sprintf(path, "%s/%s", value, eval_daemon(request));
if ((fp = fopen(path, "r")) != 0) {
while ((ch = fgetc(fp)) == 0)
write(request->fd, "", 1);
ungetc(ch, fp);
while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
if (split_at(ibuf, '\n'))
strcat(ibuf, "\r\n");
percent_x(obuf, sizeof(obuf), ibuf, request);
write(request->fd, obuf, strlen(obuf));
}
fclose(fp);
} else if (stat(value, &st) < 0) {
tcpd_warn("%s: %m", value);
}
}
/* group_option - switch group id */
/* ARGSUSED */
static void group_option(value, request)
char *value;
struct request_info *request;
{
struct group *grp;
struct group *getgrnam();
if ((grp = getgrnam(value)) == 0)
tcpd_jump("unknown group: \"%s\"", value);
endgrent();
if (dry_run == 0 && setgid(grp->gr_gid))
tcpd_jump("setgid(%s): %m", value);
}
/* user_option - switch user id */
/* ARGSUSED */
static void user_option(value, request)
char *value;
struct request_info *request;
{
struct passwd *pwd;
struct passwd *getpwnam();
char *group;
if ((group = split_at(value, '.')) != 0)
group_option(group, request);
if ((pwd = getpwnam(value)) == 0)
tcpd_jump("unknown user: \"%s\"", value);
endpwent();
if (dry_run == 0 && setuid(pwd->pw_uid))
tcpd_jump("setuid(%s): %m", value);
}
/* umask_option - set file creation mask */
/* ARGSUSED */
static void umask_option(value, request)
char *value;
struct request_info *request;
{
unsigned mask;
char junk;
if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
tcpd_jump("bad umask value: \"%s\"", value);
(void) umask(mask);
}
/* spawn_option - spawn a shell command and wait */
/* ARGSUSED */
static void spawn_option(value, request)
char *value;
struct request_info *request;
{
if (dry_run == 0)
shell_cmd(value);
}
/* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
/* ARGSUSED */
static void linger_option(value, request)
char *value;
struct request_info *request;
{
struct linger linger;
char junk;
if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
|| linger.l_linger < 0)
tcpd_jump("bad linger value: \"%s\"", value);
if (dry_run == 0) {
linger.l_onoff = (linger.l_linger != 0);
if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
sizeof(linger)) < 0)
tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
}
}
/* keepalive_option - set the socket keepalive option */
/* ARGSUSED */
static void keepalive_option(value, request)
char *value;
struct request_info *request;
{
static int on = 1;
if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
(char *) &on, sizeof(on)) < 0)
tcpd_warn("setsockopt SO_KEEPALIVE: %m");
}
/* nice_option - set nice value */
/* ARGSUSED */
static void nice_option(value, request)
char *value;
struct request_info *request;
{
int niceval = 10;
char junk;
if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
tcpd_jump("bad nice value: \"%s\"", value);
if (dry_run == 0 && nice(niceval) < 0)
tcpd_warn("nice(%d): %m", niceval);
}
/* twist_option - replace process by shell command */
static void twist_option(value, request)
char *value;
struct request_info *request;
{
char *error;
if (dry_run != 0) {
dry_run = 0;
} else {
if (resident > 0)
tcpd_jump("twist option in resident process");
syslog(deny_severity, "twist %s to %s", eval_client(request), value);
/* Before switching to the shell, set up stdin, stdout and stderr. */
#define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
if (maybe_dup2(request->fd, 0) != 0 ||
maybe_dup2(request->fd, 1) != 1 ||
maybe_dup2(request->fd, 2) != 2) {
error = "twist_option: dup: %m";
} else {
if (request->fd > 2)
close(request->fd);
(void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
error = "twist_option: /bin/sh: %m";
}
/* Something went wrong: we MUST terminate the process. */
tcpd_warn(error);
clean_exit(request);
}
}
/* rfc931_option - look up remote user name */
static void rfc931_option(value, request)
char *value;
struct request_info *request;
{
int timeout;
char junk;
if (value != 0) {
if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
tcpd_jump("bad rfc931 timeout: \"%s\"", value);
rfc931_timeout = timeout;
}
(void) eval_user(request);
}
/* setenv_option - set environment variable */
/* ARGSUSED */
static void setenv_option(value, request)
char *value;
struct request_info *request;
{
char *var_value;
if (*(var_value = value + strcspn(value, whitespace)))
*var_value++ = 0;
if (setenv(chop_string(value), chop_string(var_value), 1))
tcpd_jump("memory allocation failure");
}
/* severity_map - lookup facility or severity value */
static int severity_map(table, name)
const CODE *table;
char *name;
{
const CODE *t;
int ret = -1;
for (t = table; t->c_name; t++)
if (STR_EQ(t->c_name, name)) {
ret = t->c_val;
break;
}
if (ret == -1)
tcpd_jump("bad syslog facility or severity: \"%s\"", name);
return (ret);
}
/* severity_option - change logging severity for this event (Dave Mitchell) */
/* ARGSUSED */
static void severity_option(value, request)
char *value;
struct request_info *request;
{
char *level = split_at(value, '.');
allow_severity = deny_severity = level ?
severity_map(facilitynames, value) | severity_map(prioritynames, level)
: severity_map(prioritynames, value);
}
/* get_field - return pointer to next field in string */
static char *get_field(string)
char *string;
{
static char *last = "";
char *src;
char *dst;
char *ret;
int ch;
/*
* This function returns pointers to successive fields within a given
* string. ":" is the field separator; warn if the rule ends in one. It
* replaces a "\:" sequence by ":", without treating the result of
* substitution as field terminator. A null argument means resume search
* where the previous call terminated. This function destroys its
* argument.
*
* Work from explicit source or from memory. While processing \: we
* overwrite the input. This way we do not have to maintain buffers for
* copies of input fields.
*/
src = dst = ret = (string ? string : last);
if (src[0] == 0)
return (0);
while (ch = *src) {
if (ch == ':') {
if (*++src == 0)
tcpd_warn("rule ends in \":\"");
break;
}
if (ch == '\\' && src[1] == ':')
src++;
*dst++ = *src++;
}
last = src;
*dst = 0;
return (ret);
}
/* chop_string - strip leading and trailing blanks from string */
static char *chop_string(string)
register char *string;
{
char *start = 0;
char *end;
char *cp;
for (cp = string; *cp; cp++) {
if (!isspace(*cp)) {
if (start == 0)
start = cp;
end = cp;
}
}
return (start ? (end[1] = 0, start) : cp);
}
|