2 * General skeleton for adding options to the access control language. The
3 * features offered by this module are documented in the hosts_options(5)
4 * manual page (source file: hosts_options.5, "nroff -man" format).
6 * Notes and warnings for those who want to add features:
8 * In case of errors, abort options processing and deny access. There are too
9 * many irreversible side effects to make error recovery feasible. For
10 * example, it makes no sense to continue after we have already changed the
13 * In case of errors, do not terminate the process: the routines might be
14 * called from a long-running daemon that should run forever. Instead, call
15 * tcpd_jump() which does a non-local goto back into the hosts_access()
18 * In case of severe errors, use clean_exit() instead of directly calling
19 * exit(), or the inetd may loop on an UDP request.
21 * In verification mode (for example, with the "tcpdmatch" command) the
22 * "dry_run" flag is set. In this mode, an option function should just "say"
23 * what it is going to do instead of really doing it.
25 * Some option functions do not return (for example, the twist option passes
26 * control to another program). In verification mode (dry_run flag is set)
27 * such options should clear the "dry_run" flag to inform the caller of this
32 static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
35 /* System libraries. */
37 #include <sys/types.h>
38 #include <sys/param.h>
39 #include <sys/socket.h>
41 #include <netinet/in.h>
53 #ifndef MAXPATHNAMELEN
54 #define MAXPATHNAMELEN BUFSIZ
61 /* Options runtime support. */
63 int dry_run = 0; /* flag set in verification mode */
64 extern jmp_buf tcpd_buf; /* tcpd_jump() support */
66 /* Options parser support. */
68 static char whitespace_eq[] = "= \t\r\n";
69 #define whitespace (whitespace_eq + 1)
71 static char *get_field(); /* chew :-delimited field off string */
72 static char *chop_string(); /* strip leading and trailing blanks */
74 /* List of functions that implement the options. Add yours here. */
76 static void user_option(); /* execute "user name.group" option */
77 static void group_option(); /* execute "group name" option */
78 static void umask_option(); /* execute "umask mask" option */
79 static void linger_option(); /* execute "linger time" option */
80 static void keepalive_option(); /* execute "keepalive" option */
81 static void spawn_option(); /* execute "spawn command" option */
82 static void twist_option(); /* execute "twist command" option */
83 static void rfc931_option(); /* execute "rfc931" option */
84 static void setenv_option(); /* execute "setenv name value" */
85 static void nice_option(); /* execute "nice" option */
86 static void severity_option(); /* execute "severity value" */
87 static void allow_option(); /* execute "allow" option */
88 static void deny_option(); /* execute "deny" option */
89 static void banners_option(); /* execute "banners path" option */
91 /* Structure of the options table. */
94 char *name; /* keyword name, case is ignored */
95 void (*func) (); /* function that does the real work */
96 int flags; /* see below... */
99 #define NEED_ARG (1<<1) /* option requires argument */
100 #define USE_LAST (1<<2) /* option must be last */
101 #define OPT_ARG (1<<3) /* option has optional argument */
102 #define EXPAND_ARG (1<<4) /* do %x expansion on argument */
104 #define need_arg(o) ((o)->flags & NEED_ARG)
105 #define opt_arg(o) ((o)->flags & OPT_ARG)
106 #define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG))
107 #define use_last(o) ((o)->flags & USE_LAST)
108 #define expand_arg(o) ((o)->flags & EXPAND_ARG)
110 /* List of known keywords. Add yours here. */
112 static struct option option_table[] = {
113 "user", user_option, NEED_ARG,
114 "group", group_option, NEED_ARG,
115 "umask", umask_option, NEED_ARG,
116 "linger", linger_option, NEED_ARG,
117 "keepalive", keepalive_option, 0,
118 "spawn", spawn_option, NEED_ARG | EXPAND_ARG,
119 "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
120 "rfc931", rfc931_option, OPT_ARG,
121 "setenv", setenv_option, NEED_ARG | EXPAND_ARG,
122 "nice", nice_option, OPT_ARG,
123 "severity", severity_option, NEED_ARG,
124 "allow", allow_option, USE_LAST,
125 "deny", deny_option, USE_LAST,
126 "banners", banners_option, NEED_ARG,
130 /* process_options - process access control options */
132 void process_options(options, request)
134 struct request_info *request;
143 for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
144 next_opt = get_field((char *) 0);
147 * Separate the option into name and value parts. For backwards
148 * compatibility we ignore exactly one '=' between name and value.
150 curr_opt = chop_string(curr_opt);
151 if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
154 value += strspn(value, whitespace);
158 value += strspn(value, whitespace);
166 * Disallow missing option names (and empty option fields).
169 tcpd_jump("missing option name");
172 * Lookup the option-specific info and do some common error checks.
173 * Delegate option-specific processing to the specific functions.
176 for (op = option_table; op->name && STR_NE(op->name, key); op++)
179 tcpd_jump("bad option name: \"%s\"", key);
180 if (!value && need_arg(op))
181 tcpd_jump("option \"%s\" requires value", key);
182 if (value && !permit_arg(op))
183 tcpd_jump("option \"%s\" requires no value", key);
184 if (next_opt && use_last(op))
185 tcpd_jump("option \"%s\" must be at end", key);
186 if (value && expand_arg(op))
187 value = chop_string(percent_x(bf, sizeof(bf), value, request));
188 if (hosts_access_verbose)
189 syslog(LOG_DEBUG, "option: %s %s", key, value ? value : "");
190 (*(op->func)) (value, request);
194 /* allow_option - grant access */
198 static void allow_option(value, request)
200 struct request_info *request;
202 longjmp(tcpd_buf, AC_PERMIT);
205 /* deny_option - deny access */
209 static void deny_option(value, request)
211 struct request_info *request;
213 longjmp(tcpd_buf, AC_DENY);
216 /* banners_option - expand %<char>, terminate each line with CRLF */
218 static void banners_option(value, request)
220 struct request_info *request;
222 char path[MAXPATHNAMELEN];
224 char obuf[2 * BUFSIZ];
229 sprintf(path, "%s/%s", value, eval_daemon(request));
230 if ((fp = fopen(path, "r")) != 0) {
231 while ((ch = fgetc(fp)) == 0)
232 write(request->fd, "", 1);
234 while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
235 if (split_at(ibuf, '\n'))
236 strcat(ibuf, "\r\n");
237 percent_x(obuf, sizeof(obuf), ibuf, request);
238 write(request->fd, obuf, strlen(obuf));
241 } else if (stat(value, &st) < 0) {
242 tcpd_warn("%s: %m", value);
246 /* group_option - switch group id */
250 static void group_option(value, request)
252 struct request_info *request;
255 struct group *getgrnam();
257 if ((grp = getgrnam(value)) == 0)
258 tcpd_jump("unknown group: \"%s\"", value);
261 if (dry_run == 0 && setgid(grp->gr_gid))
262 tcpd_jump("setgid(%s): %m", value);
265 /* user_option - switch user id */
269 static void user_option(value, request)
271 struct request_info *request;
274 struct passwd *getpwnam();
277 if ((group = split_at(value, '.')) != 0)
278 group_option(group, request);
279 if ((pwd = getpwnam(value)) == 0)
280 tcpd_jump("unknown user: \"%s\"", value);
283 if (dry_run == 0 && setuid(pwd->pw_uid))
284 tcpd_jump("setuid(%s): %m", value);
287 /* umask_option - set file creation mask */
291 static void umask_option(value, request)
293 struct request_info *request;
298 if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
299 tcpd_jump("bad umask value: \"%s\"", value);
303 /* spawn_option - spawn a shell command and wait */
307 static void spawn_option(value, request)
309 struct request_info *request;
315 /* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
319 static void linger_option(value, request)
321 struct request_info *request;
323 struct linger linger;
326 if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
327 || linger.l_linger < 0)
328 tcpd_jump("bad linger value: \"%s\"", value);
330 linger.l_onoff = (linger.l_linger != 0);
331 if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
333 tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
337 /* keepalive_option - set the socket keepalive option */
341 static void keepalive_option(value, request)
343 struct request_info *request;
347 if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
348 (char *) &on, sizeof(on)) < 0)
349 tcpd_warn("setsockopt SO_KEEPALIVE: %m");
352 /* nice_option - set nice value */
356 static void nice_option(value, request)
358 struct request_info *request;
363 if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
364 tcpd_jump("bad nice value: \"%s\"", value);
365 if (dry_run == 0 && nice(niceval) < 0)
366 tcpd_warn("nice(%d): %m", niceval);
369 /* twist_option - replace process by shell command */
371 static void twist_option(value, request)
373 struct request_info *request;
381 tcpd_jump("twist option in resident process");
383 syslog(deny_severity, "twist %s to %s", eval_client(request), value);
385 /* Before switching to the shell, set up stdin, stdout and stderr. */
387 #define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
389 if (maybe_dup2(request->fd, 0) != 0 ||
390 maybe_dup2(request->fd, 1) != 1 ||
391 maybe_dup2(request->fd, 2) != 2) {
392 error = "twist_option: dup: %m";
396 (void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
397 error = "twist_option: /bin/sh: %m";
400 /* Something went wrong: we MUST terminate the process. */
407 /* rfc931_option - look up remote user name */
409 static void rfc931_option(value, request)
411 struct request_info *request;
417 if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
418 tcpd_jump("bad rfc931 timeout: \"%s\"", value);
419 rfc931_timeout = timeout;
421 (void) eval_user(request);
424 /* setenv_option - set environment variable */
428 static void setenv_option(value, request)
430 struct request_info *request;
434 if (*(var_value = value + strcspn(value, whitespace)))
436 if (setenv(chop_string(value), chop_string(var_value), 1))
437 tcpd_jump("memory allocation failure");
440 /* severity_map - lookup facility or severity value */
442 static int severity_map(table, name)
448 for (t = table; t->c_name; t++)
449 if (STR_EQ(t->c_name, name))
451 tcpd_jump("bad syslog facility or severity: \"%s\"", name);
455 /* severity_option - change logging severity for this event (Dave Mitchell) */
459 static void severity_option(value, request)
461 struct request_info *request;
463 char *level = split_at(value, '.');
465 allow_severity = deny_severity = level ?
466 severity_map(facilitynames, value) | severity_map(prioritynames, level)
467 : severity_map(prioritynames, value);
470 /* get_field - return pointer to next field in string */
472 static char *get_field(string)
475 static char *last = "";
482 * This function returns pointers to successive fields within a given
483 * string. ":" is the field separator; warn if the rule ends in one. It
484 * replaces a "\:" sequence by ":", without treating the result of
485 * substitution as field terminator. A null argument means resume search
486 * where the previous call terminated. This function destroys its
489 * Work from explicit source or from memory. While processing \: we
490 * overwrite the input. This way we do not have to maintain buffers for
491 * copies of input fields.
494 src = dst = ret = (string ? string : last);
501 tcpd_warn("rule ends in \":\"");
504 if (ch == '\\' && src[1] == ':')
513 /* chop_string - strip leading and trailing blanks from string */
515 static char *chop_string(string)
516 register char *string;
522 for (cp = string; *cp; cp++) {
529 return (start ? (end[1] = 0, start) : cp);