1/*
2 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
3 * Use is subject to license terms.
4 */
5
6#pragma ident	"%Z%%M%	%I%	%E% SMI"
7
8 /*
9  * General skeleton for adding options to the access control language. The
10  * features offered by this module are documented in the hosts_options(5)
11  * manual page (source file: hosts_options.5, "nroff -man" format).
12  *
13  * Notes and warnings for those who want to add features:
14  *
15  * In case of errors, abort options processing and deny access. There are too
16  * many irreversible side effects to make error recovery feasible. For
17  * example, it makes no sense to continue after we have already changed the
18  * userid.
19  *
20  * In case of errors, do not terminate the process: the routines might be
21  * called from a long-running daemon that should run forever. Instead, call
22  * tcpd_jump() which does a non-local goto back into the hosts_access()
23  * routine.
24  *
25  * In case of severe errors, use clean_exit() instead of directly calling
26  * exit(), or the inetd may loop on an UDP request.
27  *
28  * In verification mode (for example, with the "tcpdmatch" command) the
29  * "dry_run" flag is set. In this mode, an option function should just "say"
30  * what it is going to do instead of really doing it.
31  *
32  * Some option functions do not return (for example, the twist option passes
33  * control to another program). In verification mode (dry_run flag is set)
34  * such options should clear the "dry_run" flag to inform the caller of this
35  * course of action.
36  */
37
38#ifndef lint
39static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
40#endif
41
42/* System libraries. */
43
44#include <sys/types.h>
45#include <sys/param.h>
46#include <sys/socket.h>
47#include <sys/stat.h>
48#include <netinet/in.h>
49#include <netdb.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <unistd.h>
53#include <syslog.h>
54#include <pwd.h>
55#include <grp.h>
56#include <ctype.h>
57#include <setjmp.h>
58#include <string.h>
59
60#ifndef MAXPATHNAMELEN
61#define MAXPATHNAMELEN  BUFSIZ
62#endif
63
64/* Local stuff. */
65
66#include "tcpd.h"
67
68/* Options runtime support. */
69
70int     dry_run = 0;			/* flag set in verification mode */
71extern jmp_buf tcpd_buf;		/* tcpd_jump() support */
72
73/* Options parser support. */
74
75static char whitespace_eq[] = "= \t\r\n";
76#define whitespace (whitespace_eq + 1)
77
78static char *get_field();		/* chew :-delimited field off string */
79static char *chop_string();		/* strip leading and trailing blanks */
80
81/* List of functions that implement the options. Add yours here. */
82
83static void user_option();		/* execute "user name.group" option */
84static void group_option();		/* execute "group name" option */
85static void umask_option();		/* execute "umask mask" option */
86static void linger_option();		/* execute "linger time" option */
87static void keepalive_option();		/* execute "keepalive" option */
88static void spawn_option();		/* execute "spawn command" option */
89static void twist_option();		/* execute "twist command" option */
90static void rfc931_option();		/* execute "rfc931" option */
91static void setenv_option();		/* execute "setenv name value" */
92static void nice_option();		/* execute "nice" option */
93static void severity_option();		/* execute "severity value" */
94static void allow_option();		/* execute "allow" option */
95static void deny_option();		/* execute "deny" option */
96static void banners_option();		/* execute "banners path" option */
97
98/* Structure of the options table. */
99
100struct option {
101    char   *name;			/* keyword name, case is ignored */
102    void  (*func) ();			/* function that does the real work */
103    int     flags;			/* see below... */
104};
105
106#define NEED_ARG	(1<<1)		/* option requires argument */
107#define USE_LAST	(1<<2)		/* option must be last */
108#define OPT_ARG		(1<<3)		/* option has optional argument */
109#define EXPAND_ARG	(1<<4)		/* do %x expansion on argument */
110
111#define need_arg(o)	((o)->flags & NEED_ARG)
112#define opt_arg(o)	((o)->flags & OPT_ARG)
113#define permit_arg(o)	((o)->flags & (NEED_ARG | OPT_ARG))
114#define use_last(o)	((o)->flags & USE_LAST)
115#define expand_arg(o)	((o)->flags & EXPAND_ARG)
116
117/* List of known keywords. Add yours here. */
118
119static struct option option_table[] = {
120    "user", user_option, NEED_ARG,
121    "group", group_option, NEED_ARG,
122    "umask", umask_option, NEED_ARG,
123    "linger", linger_option, NEED_ARG,
124    "keepalive", keepalive_option, 0,
125    "spawn", spawn_option, NEED_ARG | EXPAND_ARG,
126    "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
127    "rfc931", rfc931_option, OPT_ARG,
128    "setenv", setenv_option, NEED_ARG | EXPAND_ARG,
129    "nice", nice_option, OPT_ARG,
130    "severity", severity_option, NEED_ARG,
131    "allow", allow_option, USE_LAST,
132    "deny", deny_option, USE_LAST,
133    "banners", banners_option, NEED_ARG,
134    0,
135};
136
137/* process_options - process access control options */
138
139void    process_options(options, request)
140char   *options;
141struct request_info *request;
142{
143    char   *key;
144    char   *value;
145    char   *curr_opt;
146    char   *next_opt;
147    struct option *op;
148    char    bf[BUFSIZ];
149
150    for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
151	next_opt = get_field((char *) 0);
152
153	/*
154	 * Separate the option into name and value parts. For backwards
155	 * compatibility we ignore exactly one '=' between name and value.
156	 */
157	curr_opt = chop_string(curr_opt);
158	if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
159	    if (*value != '=') {
160		*value++ = 0;
161		value += strspn(value, whitespace);
162	    }
163	    if (*value == '=') {
164		*value++ = 0;
165		value += strspn(value, whitespace);
166	    }
167	}
168	if (*value == 0)
169	    value = 0;
170	key = curr_opt;
171
172	/*
173	 * Disallow missing option names (and empty option fields).
174	 */
175	if (*key == 0)
176	    tcpd_jump("missing option name");
177
178	/*
179	 * Lookup the option-specific info and do some common error checks.
180	 * Delegate option-specific processing to the specific functions.
181	 */
182
183	for (op = option_table; op->name && STR_NE(op->name, key); op++)
184	     /* VOID */ ;
185	if (op->name == 0)
186	    tcpd_jump("bad option name: \"%s\"", key);
187	if (!value && need_arg(op))
188	    tcpd_jump("option \"%s\" requires value", key);
189	if (value && !permit_arg(op))
190	    tcpd_jump("option \"%s\" requires no value", key);
191	if (next_opt && use_last(op))
192	    tcpd_jump("option \"%s\" must be at end", key);
193	if (value && expand_arg(op))
194	    value = chop_string(percent_x(bf, sizeof(bf), value, request));
195	if (hosts_access_verbose)
196	    syslog(LOG_DEBUG, "option:   %s %s", key, value ? value : "");
197	(*(op->func)) (value, request);
198    }
199}
200
201/* allow_option - grant access */
202
203/* ARGSUSED */
204
205static void allow_option(value, request)
206char   *value;
207struct request_info *request;
208{
209    longjmp(tcpd_buf, AC_PERMIT);
210}
211
212/* deny_option - deny access */
213
214/* ARGSUSED */
215
216static void deny_option(value, request)
217char   *value;
218struct request_info *request;
219{
220    longjmp(tcpd_buf, AC_DENY);
221}
222
223/* banners_option - expand %<char>, terminate each line with CRLF */
224
225static void banners_option(value, request)
226char   *value;
227struct request_info *request;
228{
229    char    path[MAXPATHNAMELEN];
230    char    ibuf[BUFSIZ];
231    char    obuf[2 * BUFSIZ];
232    struct stat st;
233    int     ch;
234    FILE   *fp;
235
236    sprintf(path, "%s/%s", value, eval_daemon(request));
237    if ((fp = fopen(path, "r")) != 0) {
238	while ((ch = fgetc(fp)) == 0)
239	    write(request->fd, "", 1);
240	ungetc(ch, fp);
241	while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
242	    if (split_at(ibuf, '\n'))
243		strcat(ibuf, "\r\n");
244	    percent_x(obuf, sizeof(obuf), ibuf, request);
245	    write(request->fd, obuf, strlen(obuf));
246	}
247	fclose(fp);
248    } else if (stat(value, &st) < 0) {
249	tcpd_warn("%s: %m", value);
250    }
251}
252
253/* group_option - switch group id */
254
255/* ARGSUSED */
256
257static void group_option(value, request)
258char   *value;
259struct request_info *request;
260{
261    struct group *grp;
262    struct group *getgrnam();
263
264    if ((grp = getgrnam(value)) == 0)
265	tcpd_jump("unknown group: \"%s\"", value);
266    endgrent();
267
268    if (dry_run == 0 && setgid(grp->gr_gid))
269	tcpd_jump("setgid(%s): %m", value);
270}
271
272/* user_option - switch user id */
273
274/* ARGSUSED */
275
276static void user_option(value, request)
277char   *value;
278struct request_info *request;
279{
280    struct passwd *pwd;
281    struct passwd *getpwnam();
282    char   *group;
283
284    if ((group = split_at(value, '.')) != 0)
285	group_option(group, request);
286    if ((pwd = getpwnam(value)) == 0)
287	tcpd_jump("unknown user: \"%s\"", value);
288    endpwent();
289
290    if (dry_run == 0 && setuid(pwd->pw_uid))
291	tcpd_jump("setuid(%s): %m", value);
292}
293
294/* umask_option - set file creation mask */
295
296/* ARGSUSED */
297
298static void umask_option(value, request)
299char   *value;
300struct request_info *request;
301{
302    unsigned mask;
303    char    junk;
304
305    if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
306	tcpd_jump("bad umask value: \"%s\"", value);
307    (void) umask(mask);
308}
309
310/* spawn_option - spawn a shell command and wait */
311
312/* ARGSUSED */
313
314static void spawn_option(value, request)
315char   *value;
316struct request_info *request;
317{
318    if (dry_run == 0)
319	shell_cmd(value);
320}
321
322/* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
323
324/* ARGSUSED */
325
326static void linger_option(value, request)
327char   *value;
328struct request_info *request;
329{
330    struct linger linger;
331    char    junk;
332
333    if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
334	|| linger.l_linger < 0)
335	tcpd_jump("bad linger value: \"%s\"", value);
336    if (dry_run == 0) {
337	linger.l_onoff = (linger.l_linger != 0);
338	if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
339		       sizeof(linger)) < 0)
340	    tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
341    }
342}
343
344/* keepalive_option - set the socket keepalive option */
345
346/* ARGSUSED */
347
348static void keepalive_option(value, request)
349char   *value;
350struct request_info *request;
351{
352    static int on = 1;
353
354    if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
355				   (char *) &on, sizeof(on)) < 0)
356	tcpd_warn("setsockopt SO_KEEPALIVE: %m");
357}
358
359/* nice_option - set nice value */
360
361/* ARGSUSED */
362
363static void nice_option(value, request)
364char   *value;
365struct request_info *request;
366{
367    int     niceval = 10;
368    char    junk;
369
370    if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
371	tcpd_jump("bad nice value: \"%s\"", value);
372    if (dry_run == 0 && nice(niceval) < 0)
373	tcpd_warn("nice(%d): %m", niceval);
374}
375
376/* twist_option - replace process by shell command */
377
378static void twist_option(value, request)
379char   *value;
380struct request_info *request;
381{
382    char   *error;
383
384    if (dry_run != 0) {
385	dry_run = 0;
386    } else {
387	if (resident > 0)
388	    tcpd_jump("twist option in resident process");
389
390	syslog(deny_severity, "twist %s to %s", eval_client(request), value);
391
392	/* Before switching to the shell, set up stdin, stdout and stderr. */
393
394#define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
395
396	if (maybe_dup2(request->fd, 0) != 0 ||
397	    maybe_dup2(request->fd, 1) != 1 ||
398	    maybe_dup2(request->fd, 2) != 2) {
399	    error = "twist_option: dup: %m";
400	} else {
401	    if (request->fd > 2)
402		close(request->fd);
403	    (void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
404	    error = "twist_option: /bin/sh: %m";
405	}
406
407	/* Something went wrong: we MUST terminate the process. */
408
409	tcpd_warn(error);
410	clean_exit(request);
411    }
412}
413
414/* rfc931_option - look up remote user name */
415
416static void rfc931_option(value, request)
417char   *value;
418struct request_info *request;
419{
420    int     timeout;
421    char    junk;
422
423    if (value != 0) {
424	if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
425	    tcpd_jump("bad rfc931 timeout: \"%s\"", value);
426	rfc931_timeout = timeout;
427    }
428    (void) eval_user(request);
429}
430
431/* setenv_option - set environment variable */
432
433/* ARGSUSED */
434
435static void setenv_option(value, request)
436char   *value;
437struct request_info *request;
438{
439    extern int setenv(const char *, const char *, int);
440    char   *var_value;
441
442    if (*(var_value = value + strcspn(value, whitespace)))
443	*var_value++ = 0;
444    if (setenv(chop_string(value), chop_string(var_value), 1))
445	tcpd_jump("memory allocation failure");
446}
447
448 /*
449  * The severity option goes last because it comes with a huge amount of ugly
450  * #ifdefs and tables.
451  */
452
453struct syslog_names {
454    char   *name;
455    int     value;
456};
457
458static struct syslog_names log_fac[] = {
459#ifdef LOG_KERN
460    "kern", LOG_KERN,
461#endif
462#ifdef LOG_USER
463    "user", LOG_USER,
464#endif
465#ifdef LOG_MAIL
466    "mail", LOG_MAIL,
467#endif
468#ifdef LOG_DAEMON
469    "daemon", LOG_DAEMON,
470#endif
471#ifdef LOG_AUTH
472    "auth", LOG_AUTH,
473#endif
474#ifdef LOG_LPR
475    "lpr", LOG_LPR,
476#endif
477#ifdef LOG_NEWS
478    "news", LOG_NEWS,
479#endif
480#ifdef LOG_UUCP
481    "uucp", LOG_UUCP,
482#endif
483#ifdef LOG_CRON
484    "cron", LOG_CRON,
485#endif
486#ifdef LOG_LOCAL0
487    "local0", LOG_LOCAL0,
488#endif
489#ifdef LOG_LOCAL1
490    "local1", LOG_LOCAL1,
491#endif
492#ifdef LOG_LOCAL2
493    "local2", LOG_LOCAL2,
494#endif
495#ifdef LOG_LOCAL3
496    "local3", LOG_LOCAL3,
497#endif
498#ifdef LOG_LOCAL4
499    "local4", LOG_LOCAL4,
500#endif
501#ifdef LOG_LOCAL5
502    "local5", LOG_LOCAL5,
503#endif
504#ifdef LOG_LOCAL6
505    "local6", LOG_LOCAL6,
506#endif
507#ifdef LOG_LOCAL7
508    "local7", LOG_LOCAL7,
509#endif
510    0,
511};
512
513static struct syslog_names log_sev[] = {
514#ifdef LOG_EMERG
515    "emerg", LOG_EMERG,
516#endif
517#ifdef LOG_ALERT
518    "alert", LOG_ALERT,
519#endif
520#ifdef LOG_CRIT
521    "crit", LOG_CRIT,
522#endif
523#ifdef LOG_ERR
524    "err", LOG_ERR,
525#endif
526#ifdef LOG_WARNING
527    "warning", LOG_WARNING,
528#endif
529#ifdef LOG_NOTICE
530    "notice", LOG_NOTICE,
531#endif
532#ifdef LOG_INFO
533    "info", LOG_INFO,
534#endif
535#ifdef LOG_DEBUG
536    "debug", LOG_DEBUG,
537#endif
538    0,
539};
540
541/* severity_map - lookup facility or severity value */
542
543static int severity_map(table, name)
544struct syslog_names *table;
545char   *name;
546{
547    struct syslog_names *t;
548
549    for (t = table; t->name; t++)
550	if (STR_EQ(t->name, name))
551	    return (t->value);
552    tcpd_jump("bad syslog facility or severity: \"%s\"", name);
553    /* NOTREACHED */
554}
555
556/* severity_option - change logging severity for this event (Dave Mitchell) */
557
558/* ARGSUSED */
559
560static void severity_option(value, request)
561char   *value;
562struct request_info *request;
563{
564    char   *level = split_at(value, '.');
565
566    allow_severity = deny_severity = level ?
567	severity_map(log_fac, value) | severity_map(log_sev, level) :
568	severity_map(log_sev, value);
569}
570
571/* get_field - return pointer to next field in string */
572
573static char *get_field(string)
574char   *string;
575{
576    static char *last = "";
577    char   *src;
578    char   *dst;
579    char   *ret;
580    int     ch;
581
582    /*
583     * This function returns pointers to successive fields within a given
584     * string. ":" is the field separator; warn if the rule ends in one. It
585     * replaces a "\:" sequence by ":", without treating the result of
586     * substitution as field terminator. A null argument means resume search
587     * where the previous call terminated. This function destroys its
588     * argument.
589     *
590     * Work from explicit source or from memory. While processing \: we
591     * overwrite the input. This way we do not have to maintain buffers for
592     * copies of input fields.
593     */
594
595    src = dst = ret = (string ? string : last);
596    if (src[0] == 0)
597	return (0);
598
599    while (ch = *src) {
600	if (ch == ':') {
601	    if (*++src == 0)
602		tcpd_warn("rule ends in \":\"");
603	    break;
604	}
605	if (ch == '\\' && src[1] == ':')
606	    src++;
607	*dst++ = *src++;
608    }
609    last = src;
610    *dst = 0;
611    return (ret);
612}
613
614/* chop_string - strip leading and trailing blanks from string */
615
616static char *chop_string(string)
617register char *string;
618{
619    char   *start = 0;
620    char   *end;
621    char   *cp;
622
623    for (cp = string; *cp; cp++) {
624	if (!isspace(*cp)) {
625	    if (start == 0)
626		start = cp;
627	    end = cp;
628	}
629    }
630    return (start ? (end[1] = 0, start) : cp);
631}
632