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
34 static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
37 /* System libraries. */
39 #include <sys/types.h>
40 #include <sys/param.h>
41 #include <sys/socket.h>
43 #include <netinet/in.h>
54 #ifndef MAXPATHNAMELEN
55 #define MAXPATHNAMELEN BUFSIZ
62 /* Options runtime support. */
64 int dry_run = 0; /* flag set in verification mode */
65 extern jmp_buf tcpd_buf; /* tcpd_jump() support */
67 /* Options parser support. */
69 static char whitespace_eq[] = "= \t\r\n";
70 #define whitespace (whitespace_eq + 1)
72 static char *get_field(); /* chew :-delimited field off string */
73 static char *chop_string(); /* strip leading and trailing blanks */
75 /* List of functions that implement the options. Add yours here. */
77 static void user_option(); /* execute "user name.group" option */
78 static void group_option(); /* execute "group name" option */
79 static void umask_option(); /* execute "umask mask" option */
80 static void linger_option(); /* execute "linger time" option */
81 static void keepalive_option(); /* execute "keepalive" option */
82 static void spawn_option(); /* execute "spawn command" option */
83 static void twist_option(); /* execute "twist command" option */
84 static void rfc931_option(); /* execute "rfc931" option */
85 static void setenv_option(); /* execute "setenv name value" */
86 static void nice_option(); /* execute "nice" option */
87 static void severity_option(); /* execute "severity value" */
88 static void allow_option(); /* execute "allow" option */
89 static void deny_option(); /* execute "deny" option */
90 static void banners_option(); /* execute "banners path" option */
92 /* Structure of the options table. */
95 char *name; /* keyword name, case is ignored */
96 void (*func) (); /* function that does the real work */
97 int flags; /* see below... */
100 #define NEED_ARG (1<<1) /* option requires argument */
101 #define USE_LAST (1<<2) /* option must be last */
102 #define OPT_ARG (1<<3) /* option has optional argument */
103 #define EXPAND_ARG (1<<4) /* do %x expansion on argument */
105 #define need_arg(o) ((o)->flags & NEED_ARG)
106 #define opt_arg(o) ((o)->flags & OPT_ARG)
107 #define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG))
108 #define use_last(o) ((o)->flags & USE_LAST)
109 #define expand_arg(o) ((o)->flags & EXPAND_ARG)
111 /* List of known keywords. Add yours here. */
113 static struct option option_table[] = {
114 "user", user_option, NEED_ARG,
115 "group", group_option, NEED_ARG,
116 "umask", umask_option, NEED_ARG,
117 "linger", linger_option, NEED_ARG,
118 "keepalive", keepalive_option, 0,
119 "spawn", spawn_option, NEED_ARG | EXPAND_ARG,
120 "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
121 "rfc931", rfc931_option, OPT_ARG,
122 "setenv", setenv_option, NEED_ARG | EXPAND_ARG,
123 "nice", nice_option, OPT_ARG,
124 "severity", severity_option, NEED_ARG,
125 "allow", allow_option, USE_LAST,
126 "deny", deny_option, USE_LAST,
127 "banners", banners_option, NEED_ARG,
131 /* process_options - process access control options */
133 void process_options(options, request)
135 struct request_info *request;
144 for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
145 next_opt = get_field((char *) 0);
148 * Separate the option into name and value parts. For backwards
149 * compatibility we ignore exactly one '=' between name and value.
151 curr_opt = chop_string(curr_opt);
152 if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
155 value += strspn(value, whitespace);
159 value += strspn(value, whitespace);
167 * Disallow missing option names (and empty option fields).
170 tcpd_jump("missing option name");
173 * Lookup the option-specific info and do some common error checks.
174 * Delegate option-specific processing to the specific functions.
177 for (op = option_table; op->name && STR_NE(op->name, key); op++)
180 tcpd_jump("bad option name: \"%s\"", key);
181 if (!value && need_arg(op))
182 tcpd_jump("option \"%s\" requires value", key);
183 if (value && !permit_arg(op))
184 tcpd_jump("option \"%s\" requires no value", key);
185 if (next_opt && use_last(op))
186 tcpd_jump("option \"%s\" must be at end", key);
187 if (value && expand_arg(op))
188 value = chop_string(percent_x(bf, sizeof(bf), value, request));
189 if (hosts_access_verbose)
190 syslog(LOG_DEBUG, "option: %s %s", key, value ? value : "");
191 (*(op->func)) (value, request);
195 /* allow_option - grant access */
199 static void allow_option(value, request)
201 struct request_info *request;
203 longjmp(tcpd_buf, AC_PERMIT);
206 /* deny_option - deny access */
210 static void deny_option(value, request)
212 struct request_info *request;
214 longjmp(tcpd_buf, AC_DENY);
217 /* banners_option - expand %<char>, terminate each line with CRLF */
219 static void banners_option(value, request)
221 struct request_info *request;
223 char path[MAXPATHNAMELEN];
225 char obuf[2 * BUFSIZ];
230 sprintf(path, "%s/%s", value, eval_daemon(request));
231 if ((fp = fopen(path, "r")) != 0) {
232 while ((ch = fgetc(fp)) == 0)
233 write(request->fd, "", 1);
235 while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
236 if (split_at(ibuf, '\n'))
237 strcat(ibuf, "\r\n");
238 percent_x(obuf, sizeof(obuf), ibuf, request);
239 write(request->fd, obuf, strlen(obuf));
242 } else if (stat(value, &st) < 0) {
243 tcpd_warn("%s: %m", value);
247 /* group_option - switch group id */
251 static void group_option(value, request)
253 struct request_info *request;
256 struct group *getgrnam();
258 if ((grp = getgrnam(value)) == 0)
259 tcpd_jump("unknown group: \"%s\"", value);
262 if (dry_run == 0 && setgid(grp->gr_gid))
263 tcpd_jump("setgid(%s): %m", value);
266 /* user_option - switch user id */
270 static void user_option(value, request)
272 struct request_info *request;
275 struct passwd *getpwnam();
278 if ((group = split_at(value, '.')) != 0)
279 group_option(group, request);
280 if ((pwd = getpwnam(value)) == 0)
281 tcpd_jump("unknown user: \"%s\"", value);
284 if (dry_run == 0 && setuid(pwd->pw_uid))
285 tcpd_jump("setuid(%s): %m", value);
288 /* umask_option - set file creation mask */
292 static void umask_option(value, request)
294 struct request_info *request;
299 if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
300 tcpd_jump("bad umask value: \"%s\"", value);
304 /* spawn_option - spawn a shell command and wait */
308 static void spawn_option(value, request)
310 struct request_info *request;
316 /* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
320 static void linger_option(value, request)
322 struct request_info *request;
324 struct linger linger;
327 if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
328 || linger.l_linger < 0)
329 tcpd_jump("bad linger value: \"%s\"", value);
331 linger.l_onoff = (linger.l_linger != 0);
332 if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
334 tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
338 /* keepalive_option - set the socket keepalive option */
342 static void keepalive_option(value, request)
344 struct request_info *request;
348 if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
349 (char *) &on, sizeof(on)) < 0)
350 tcpd_warn("setsockopt SO_KEEPALIVE: %m");
353 /* nice_option - set nice value */
357 static void nice_option(value, request)
359 struct request_info *request;
364 if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
365 tcpd_jump("bad nice value: \"%s\"", value);
366 if (dry_run == 0 && nice(niceval) < 0)
367 tcpd_warn("nice(%d): %m", niceval);
370 /* twist_option - replace process by shell command */
372 static void twist_option(value, request)
374 struct request_info *request;
382 tcpd_jump("twist option in resident process");
384 syslog(deny_severity, "twist %s to %s", eval_client(request), value);
386 /* Before switching to the shell, set up stdin, stdout and stderr. */
388 #define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
390 if (maybe_dup2(request->fd, 0) != 0 ||
391 maybe_dup2(request->fd, 1) != 1 ||
392 maybe_dup2(request->fd, 2) != 2) {
393 error = "twist_option: dup: %m";
397 (void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
398 error = "twist_option: /bin/sh: %m";
401 /* Something went wrong: we MUST terminate the process. */
408 /* rfc931_option - look up remote user name */
410 static void rfc931_option(value, request)
412 struct request_info *request;
418 if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
419 tcpd_jump("bad rfc931 timeout: \"%s\"", value);
420 rfc931_timeout = timeout;
422 (void) eval_user(request);
425 /* setenv_option - set environment variable */
429 static void setenv_option(value, request)
431 struct request_info *request;
435 if (*(var_value = value + strcspn(value, whitespace)))
437 if (setenv(chop_string(value), chop_string(var_value), 1))
438 tcpd_jump("memory allocation failure");
441 /* severity_map - lookup facility or severity value */
443 static int severity_map(table, name)
449 for (t = table; t->c_name; t++)
450 if (STR_EQ(t->c_name, name))
452 tcpd_jump("bad syslog facility or severity: \"%s\"", name);
456 /* severity_option - change logging severity for this event (Dave Mitchell) */
460 static void severity_option(value, request)
462 struct request_info *request;
464 char *level = split_at(value, '.');
466 allow_severity = deny_severity = level ?
467 severity_map(facilitynames, value) | severity_map(prioritynames, level)
468 : severity_map(prioritynames, value);
471 /* get_field - return pointer to next field in string */
473 static char *get_field(string)
476 static char *last = "";
483 * This function returns pointers to successive fields within a given
484 * string. ":" is the field separator; warn if the rule ends in one. It
485 * replaces a "\:" sequence by ":", without treating the result of
486 * substitution as field terminator. A null argument means resume search
487 * where the previous call terminated. This function destroys its
490 * Work from explicit source or from memory. While processing \: we
491 * overwrite the input. This way we do not have to maintain buffers for
492 * copies of input fields.
495 src = dst = ret = (string ? string : last);
502 tcpd_warn("rule ends in \":\"");
505 if (ch == '\\' && src[1] == ':')
514 /* chop_string - strip leading and trailing blanks from string */
516 static char *chop_string(string)
517 register char *string;
523 for (cp = string; *cp; cp++) {
530 return (start ? (end[1] = 0, start) : cp);