1 /* $OpenBSD: authpf.c,v 1.112 2009/01/10 19:08:53 miod Exp $ */
4 * Copyright (C) 1998 - 2007 Bob Beck (beck@openbsd.org).
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 #include <sys/cdefs.h>
20 __FBSDID("$FreeBSD$");
22 #include <sys/types.h>
24 #include <sys/ioctl.h>
25 #include <sys/socket.h>
31 #include <net/pfvar.h>
32 #include <arpa/inet.h>
39 #include <login_cap.h>
49 #include "pathnames.h"
51 static int read_config(FILE *);
52 static void print_message(const char *);
53 static int allowed_luser(struct passwd *);
54 static int check_luser(const char *, char *);
55 static int remove_stale_rulesets(void);
56 static int recursive_ruleset_purge(char *, char *);
57 static int change_filter(int, const char *, const char *);
58 static int change_table(int, const char *);
59 static void authpf_kill_states(void);
61 int dev; /* pf device */
62 char anchorname[PF_ANCHOR_NAME_SIZE] = "authpf";
63 char rulesetname[MAXPATHLEN - PF_ANCHOR_NAME_SIZE - 2];
64 char tablename[PF_TABLE_NAME_SIZE] = "authpf_users";
65 int user_ip = 1; /* controls whether $user_ip is set */
69 char luser[MAXLOGNAME]; /* username */
70 char ipsrc[256]; /* ip as a string */
71 char pidfile[MAXPATHLEN]; /* we save pid in this file. */
73 struct timeval Tstart, Tend; /* start and end times of session */
75 volatile sig_atomic_t want_death;
76 static void need_death(int signo);
78 static __dead2 void do_death(int);
80 static __dead void do_death(int);
82 extern char *__progname; /* program name */
85 * User shell for authenticating gateways. Sole purpose is to allow
86 * a user to ssh to a gateway, and have the gateway modify packet
87 * filters to allow access, then remove access when the user finishes
88 * up. Meant to be used only from ssh(1) connections.
103 if (strcmp(__progname, "-authpf-noip") == 0)
106 config = fopen(PATH_CONFFILE, "r");
107 if (config == NULL) {
108 syslog(LOG_ERR, "cannot open %s (%m)", PATH_CONFFILE);
112 if ((cp = getenv("SSH_TTY")) == NULL) {
113 syslog(LOG_ERR, "non-interactive session connection for authpf");
117 if ((cp = getenv("SSH_CLIENT")) == NULL) {
118 syslog(LOG_ERR, "cannot determine connection source");
122 if (strlcpy(ipsrc, cp, sizeof(ipsrc)) >= sizeof(ipsrc)) {
123 syslog(LOG_ERR, "SSH_CLIENT variable too long");
126 cp = strchr(ipsrc, ' ');
128 syslog(LOG_ERR, "corrupt SSH_CLIENT variable %s", ipsrc);
132 if (inet_pton(AF_INET, ipsrc, &ina) != 1 &&
133 inet_pton(AF_INET6, ipsrc, &ina) != 1) {
135 "cannot determine IP from SSH_CLIENT %s", ipsrc);
138 /* open the pf device */
139 dev = open(PATH_DEVFILE, O_RDWR);
141 syslog(LOG_ERR, "cannot open packet filter device (%m)");
148 syslog(LOG_ERR, "cannot find user for uid %u", uid);
152 if ((lc = login_getclass(pw->pw_class)) != NULL)
153 shell = login_getcapstr(lc, "shell", pw->pw_shell,
156 shell = pw->pw_shell;
162 if (strcmp(shell, PATH_AUTHPF_SHELL) &&
163 strcmp(shell, PATH_AUTHPF_SHELL_NOIP)) {
164 syslog(LOG_ERR, "wrong shell for user %s, uid %u",
165 pw->pw_name, pw->pw_uid);
169 if (shell != pw->pw_shell)
178 if (shell != pw->pw_shell)
183 * Paranoia, but this data _does_ come from outside authpf, and
184 * truncation would be bad.
186 if (strlcpy(luser, pw->pw_name, sizeof(luser)) >= sizeof(luser)) {
187 syslog(LOG_ERR, "username too long: %s", pw->pw_name);
191 if ((n = snprintf(rulesetname, sizeof(rulesetname), "%s(%ld)",
192 luser, (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
193 syslog(LOG_INFO, "%s(%ld) too large, ruleset name will be %ld",
194 luser, (long)getpid(), (long)getpid());
195 if ((n = snprintf(rulesetname, sizeof(rulesetname), "%ld",
196 (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
197 syslog(LOG_ERR, "pid too large for ruleset name");
203 /* Make our entry in /var/authpf as ipaddr or username */
204 n = snprintf(pidfile, sizeof(pidfile), "%s/%s",
205 PATH_PIDFILE, user_ip ? ipsrc : luser);
206 if (n < 0 || (u_int)n >= sizeof(pidfile)) {
207 syslog(LOG_ERR, "path to pidfile too long");
211 signal(SIGTERM, need_death);
212 signal(SIGINT, need_death);
213 signal(SIGALRM, need_death);
214 signal(SIGPIPE, need_death);
215 signal(SIGHUP, need_death);
216 signal(SIGQUIT, need_death);
217 signal(SIGTSTP, need_death);
220 * If someone else is already using this ip, then this person
221 * wants to switch users - so kill the old process and exit
224 * Note, we could print a message and tell them to log out, but the
225 * usual case of this is that someone has left themselves logged in,
226 * with the authenticated connection iconized and someone else walks
227 * up to use and automatically logs in before using. If this just
228 * gets rid of the old one silently, the new user never knows they
229 * could have used someone else's old authentication. If we
230 * tell them to log out before switching users it is an invitation
235 int save_errno, otherpid = -1;
236 char otherluser[MAXLOGNAME];
238 if ((pidfd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1 ||
239 (pidfp = fdopen(pidfd, "r+")) == NULL) {
242 syslog(LOG_ERR, "cannot open or create %s: %s", pidfile,
247 if (flock(fileno(pidfp), LOCK_EX|LOCK_NB) == 0)
251 /* Mark our pid, and username to our file. */
254 /* 31 == MAXLOGNAME - 1 */
255 if (fscanf(pidfp, "%d\n%31s\n", &otherpid, otherluser) != 2)
257 syslog(LOG_DEBUG, "tried to lock %s, in use by pid %d: %s",
258 pidfile, otherpid, strerror(save_errno));
262 "killing prior auth (pid %d) of %s by user %s",
263 otherpid, ipsrc, otherluser);
264 if (kill((pid_t) otherpid, SIGTERM) == -1) {
266 "could not kill process %d: (%m)",
272 * We try to kill the previous process and acquire the lock
273 * for 10 seconds, trying once a second. if we can't after
274 * 10 attempts we log an error and give up.
276 if (want_death || ++lockcnt > 10) {
278 syslog(LOG_ERR, "cannot kill previous authpf (pid %d)",
287 /* re-open, and try again. The previous authpf process
288 * we killed above should unlink the file and release
289 * it's lock, giving us a chance to get it now
296 /* whack the group list */
298 if (setgroups(1, &gid) == -1) {
299 syslog(LOG_INFO, "setgroups: %s", strerror(errno));
305 if (setresuid(uid, uid, uid) == -1) {
306 syslog(LOG_INFO, "setresuid: %s", strerror(errno));
309 openlog("authpf", LOG_PID | LOG_NDELAY, LOG_DAEMON);
311 if (!check_luser(PATH_BAN_DIR, luser) || !allowed_luser(pw)) {
312 syslog(LOG_INFO, "user %s prohibited", luser);
316 if (read_config(config)) {
317 syslog(LOG_ERR, "invalid config file %s", PATH_CONFFILE);
321 if (remove_stale_rulesets()) {
322 syslog(LOG_INFO, "error removing stale rulesets");
326 /* We appear to be making headway, so actually mark our pid */
328 fprintf(pidfp, "%ld\n%s\n", (long)getpid(), luser);
330 (void) ftruncate(fileno(pidfp), ftello(pidfp));
332 if (change_filter(1, luser, ipsrc) == -1) {
333 printf("Unable to modify filters\r\n");
336 if (user_ip && change_table(1, ipsrc) == -1) {
337 printf("Unable to modify table\r\n");
338 change_filter(0, luser, ipsrc);
343 printf("\r\nHello %s. ", luser);
344 printf("You are authenticated from host \"%s\"\r\n", ipsrc);
345 setproctitle("%s@%s", luser, ipsrc);
346 print_message(PATH_MESSAGE);
356 printf("\r\n\r\nSorry, this service is currently unavailable due to ");
357 printf("technical difficulties\r\n\r\n");
358 print_message(PATH_PROBLEM);
359 printf("\r\nYour authentication process (pid %ld) was unable to run\n",
361 sleep(180); /* them lusers read reaaaaal slow */
367 * reads config file in PATH_CONFFILE to set optional behaviours up
377 char *pair[4], *cp, *tp;
380 if (fgets(buf, sizeof(buf), f) == NULL) {
388 if (buf[len - 1] != '\n' && !feof(f)) {
389 syslog(LOG_ERR, "line %d too long in %s", i,
395 for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
398 if (!*cp || *cp == '#' || *cp == '\n')
401 for (ap = pair; ap < &pair[3] &&
402 (*ap = strsep(&cp, "=")) != NULL; ) {
409 tp = pair[1] + strlen(pair[1]);
410 while ((*tp == ' ' || *tp == '\t') && tp >= pair[1])
413 if (strcasecmp(pair[0], "anchor") == 0) {
414 if (!pair[1][0] || strlcpy(anchorname, pair[1],
415 sizeof(anchorname)) >= sizeof(anchorname))
418 if (strcasecmp(pair[0], "table") == 0) {
419 if (!pair[1][0] || strlcpy(tablename, pair[1],
420 sizeof(tablename)) >= sizeof(tablename))
423 } while (!feof(f) && !ferror(f));
429 syslog(LOG_ERR, "parse error, line %d of %s", i, PATH_CONFFILE);
435 * splatter a file to stdout - max line length of 1024,
436 * used for spitting message files at users to tell them
437 * they've been bad or we're unavailable.
440 print_message(const char *filename)
445 if ((f = fopen(filename, "r")) == NULL)
446 return; /* fail silently, we don't care if it isn't there */
449 if (fgets(buf, sizeof(buf), f) == NULL) {
454 } while (fputs(buf, stdout) != EOF && !feof(f));
460 * allowed_luser checks to see if user "luser" is allowed to
461 * use this gateway by virtue of being listed in an allowed
462 * users file, namely /etc/authpf/authpf.allow .
463 * Users may be listed by <username>, %<group>, or @<login_class>.
465 * If /etc/authpf/authpf.allow does not exist, then we assume that
466 * all users who are allowed in by sshd(8) are permitted to
467 * use this gateway. If /etc/authpf/authpf.allow does exist, then a
468 * user must be listed if the connection is to continue, else
469 * the session terminates in the same manner as being banned.
472 allowed_luser(struct passwd *pw)
479 if ((f = fopen(PATH_ALLOWFILE, "r")) == NULL) {
480 if (errno == ENOENT) {
482 * allowfile doesn't exist, thus this gateway
483 * isn't restricted to certain users...
489 * luser may in fact be allowed, but we can't open
490 * the file even though it's there. probably a config
493 syslog(LOG_ERR, "cannot open allowed users file %s (%s)",
494 PATH_ALLOWFILE, strerror(errno));
498 * /etc/authpf/authpf.allow exists, thus we do a linear
499 * search to see if they are allowed.
500 * also, if username "*" exists, then this is a
501 * "public" gateway, such as it is, so let
504 int gl_init = 0, ngroups = NGROUPS + 1;
505 gid_t groups[NGROUPS + 1];
510 while ((buf = fgetln(f, &len))) {
512 if (buf[len - 1] == '\n')
515 if ((lbuf = (char *)malloc(len + 1)) == NULL)
517 memcpy(lbuf, buf, len);
523 /* check login class */
524 if (strcmp(pw->pw_class, buf + 1) == 0)
526 } else if (buf[0] == '%') {
527 /* check group membership */
531 if ((group = getgrnam(buf + 1)) == NULL) {
533 "invalid group '%s' in %s (%s)",
534 buf + 1, PATH_ALLOWFILE,
540 (void) getgrouplist(pw->pw_name,
541 pw->pw_gid, groups, &ngroups);
545 for ( cnt = 0; cnt < ngroups; cnt++) {
546 if (group->gr_gid == groups[cnt]) {
552 /* check username and wildcard */
553 matched = strcmp(pw->pw_name, buf) == 0 ||
554 strcmp("*", buf) == 0;
563 return (1); /* matched an allowed user/group */
565 syslog(LOG_INFO, "denied access to %s: not listed in %s",
566 pw->pw_name, PATH_ALLOWFILE);
569 sprintf(buf, "%s", "\n\nSorry, you are not allowed to use this facility!\n");
577 * check_luser checks to see if user "luser" has been banned
578 * from using us by virtue of having an file of the same name
579 * in the "luserdir" directory.
581 * If the user has been banned, we copy the contents of the file
582 * to the user's screen. (useful for telling the user what to
583 * do to get un-banned, or just to tell them they aren't
584 * going to be un-banned.)
587 check_luser(const char *luserdir, char *l_user)
591 char tmp[MAXPATHLEN];
593 n = snprintf(tmp, sizeof(tmp), "%s/%s", luserdir, l_user);
594 if (n < 0 || (u_int)n >= sizeof(tmp)) {
595 syslog(LOG_ERR, "provided banned directory line too long (%s)",
599 if ((f = fopen(tmp, "r")) == NULL) {
600 if (errno == ENOENT) {
602 * file or dir doesn't exist, so therefore
603 * this luser isn't banned.. all is well
608 * luser may in fact be banned, but we can't open the
609 * file even though it's there. probably a config
612 syslog(LOG_ERR, "cannot open banned file %s (%s)",
613 tmp, strerror(errno));
618 * luser is banned - spit the file at them to
619 * tell what they can do and where they can go.
621 syslog(LOG_INFO, "denied access to %s: %s exists",
625 strlcpy(tmp, "\n\n-**- Sorry, you have been banned! -**-\n\n",
627 while (fputs(tmp, stdout) != EOF && !feof(f)) {
628 if (fgets(tmp, sizeof(tmp), f) == NULL) {
641 * Search for rulesets left by other authpf processes (either because they
642 * died ungracefully or were terminated) and remove them.
645 remove_stale_rulesets(void)
647 struct pfioc_ruleset prs;
650 memset(&prs, 0, sizeof(prs));
651 strlcpy(prs.path, anchorname, sizeof(prs.path));
652 if (ioctl(dev, DIOCGETRULESETS, &prs)) {
665 if (ioctl(dev, DIOCGETRULESET, &prs))
668 if ((t = strchr(prs.name, '(')) == NULL)
672 pid = strtoul(t, &s, 10);
673 if (!prs.name[0] || errno ||
674 (*s && (t == prs.name || *s != ')')))
676 if ((kill(pid, 0) && errno != EPERM) || pid == getpid()) {
677 if (recursive_ruleset_purge(anchorname, prs.name))
686 recursive_ruleset_purge(char *an, char *rs)
688 struct pfioc_trans_e *t_e = NULL;
689 struct pfioc_trans *t = NULL;
690 struct pfioc_ruleset *prs = NULL;
696 if ((t = calloc(1, sizeof(struct pfioc_trans))) == NULL)
698 if ((t_e = calloc(PF_RULESET_MAX+1,
699 sizeof(struct pfioc_trans_e))) == NULL)
701 t->size = PF_RULESET_MAX+1;
702 t->esize = sizeof(struct pfioc_trans_e);
704 for (i = 0; i < PF_RULESET_MAX+1; ++i) {
706 snprintf(t_e[i].anchor, sizeof(t_e[i].anchor), "%s/%s", an, rs);
708 t_e[PF_RULESET_MAX].rs_num = PF_RULESET_TABLE;
709 if ((ioctl(dev, DIOCXBEGIN, t) ||
710 ioctl(dev, DIOCXCOMMIT, t)) &&
714 /* purge any children */
715 if ((prs = calloc(1, sizeof(struct pfioc_ruleset))) == NULL)
717 snprintf(prs->path, sizeof(prs->path), "%s/%s", an, rs);
718 if (ioctl(dev, DIOCGETRULESETS, prs)) {
727 if (ioctl(dev, DIOCGETRULESET, prs))
730 if (recursive_ruleset_purge(prs->path, prs->name))
738 syslog(LOG_ERR, "calloc failed");
748 * Add/remove filter entries for user "luser" from ip "ipsrc"
751 change_filter(int add, const char *l_user, const char *ip_src)
753 char *fdpath = NULL, *userstr = NULL, *ipstr = NULL;
754 char *rsn = NULL, *fn = NULL;
762 "pfctl", "-p", "/dev/pf", "-q", "-a", "anchor/ruleset",
763 "-D", "user_id=X", "-D", "user_ip=X", "-f", "file", NULL
766 if (l_user == NULL || !l_user[0] || ip_src == NULL || !ip_src[0]) {
767 syslog(LOG_ERR, "invalid luser/ipsrc");
771 if (asprintf(&rsn, "%s/%s", anchorname, rulesetname) == -1)
773 if (asprintf(&fdpath, "/dev/fd/%d", dev) == -1)
775 if (asprintf(&ipstr, "user_ip=%s", ip_src) == -1)
777 if (asprintf(&userstr, "user_id=%s", l_user) == -1)
779 if (asprintf(&fn, "%s/%s/authpf.rules",
780 PATH_USER_DIR, l_user) == -1)
782 if (stat(fn, &sb) == -1) {
784 if ((fn = strdup(PATH_PFRULES)) == NULL)
799 switch (pid = fork()) {
801 syslog(LOG_ERR, "fork failed");
804 /* revoke group privs before exec */
806 if (setregid(gid, gid) == -1) {
809 execvp(PATH_PFCTL, pargv);
810 warn("exec of %s failed", PATH_PFCTL);
817 syslog(LOG_ERR, "pfctl exited abnormally");
821 gettimeofday(&Tstart, NULL);
822 syslog(LOG_INFO, "allowing %s, user %s", ip_src, l_user);
824 remove_stale_rulesets();
826 gettimeofday(&Tend, NULL);
827 syslog(LOG_INFO, "removed %s, user %s - duration %ju seconds",
828 ip_src, l_user, (uintmax_t)(Tend.tv_sec - Tstart.tv_sec));
832 syslog(LOG_ERR, "malloc failed");
843 * Add/remove this IP from the "authpf_users" table.
846 change_table(int add, const char *ip_src)
848 struct pfioc_table io;
849 struct pfr_addr addr;
851 bzero(&io, sizeof(io));
852 strlcpy(io.pfrio_table.pfrt_name, tablename,
853 sizeof(io.pfrio_table.pfrt_name));
854 io.pfrio_buffer = &addr;
855 io.pfrio_esize = sizeof(addr);
858 bzero(&addr, sizeof(addr));
859 if (ip_src == NULL || !ip_src[0])
861 if (inet_pton(AF_INET, ip_src, &addr.pfra_ip4addr) == 1) {
862 addr.pfra_af = AF_INET;
864 } else if (inet_pton(AF_INET6, ip_src, &addr.pfra_ip6addr) == 1) {
865 addr.pfra_af = AF_INET6;
868 syslog(LOG_ERR, "invalid ipsrc");
872 if (ioctl(dev, add ? DIOCRADDADDRS : DIOCRDELADDRS, &io) &&
874 syslog(LOG_ERR, "cannot %s %s from table %s: %s",
875 add ? "add" : "remove", ip_src, tablename,
883 * This is to kill off states that would otherwise be left behind stateful
884 * rules. This means we don't need to allow in more traffic than we really
885 * want to, since we don't have to worry about any luser sessions lasting
886 * longer than their ssh session. This function is based on
887 * pfctl_kill_states from pfctl.
890 authpf_kill_states(void)
892 struct pfioc_state_kill psk;
893 struct pf_addr target;
895 memset(&psk, 0, sizeof(psk));
896 memset(&target, 0, sizeof(target));
898 if (inet_pton(AF_INET, ipsrc, &target.v4) == 1)
899 psk.psk_af = AF_INET;
900 else if (inet_pton(AF_INET6, ipsrc, &target.v6) == 1)
901 psk.psk_af = AF_INET6;
903 syslog(LOG_ERR, "inet_pton(%s) failed", ipsrc);
907 /* Kill all states from ipsrc */
908 memcpy(&psk.psk_src.addr.v.a.addr, &target,
909 sizeof(psk.psk_src.addr.v.a.addr));
910 memset(&psk.psk_src.addr.v.a.mask, 0xff,
911 sizeof(psk.psk_src.addr.v.a.mask));
912 if (ioctl(dev, DIOCKILLSTATES, &psk))
913 syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");
915 /* Kill all states to ipsrc */
916 memset(&psk.psk_src, 0, sizeof(psk.psk_src));
917 memcpy(&psk.psk_dst.addr.v.a.addr, &target,
918 sizeof(psk.psk_dst.addr.v.a.addr));
919 memset(&psk.psk_dst.addr.v.a.mask, 0xff,
920 sizeof(psk.psk_dst.addr.v.a.mask));
921 if (ioctl(dev, DIOCKILLSTATES, &psk))
922 syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");
925 /* signal handler that makes us go away properly */
927 need_death(int signo __unused)
933 * function that removes our stuff when we go away.
945 change_filter(0, luser, ipsrc);
947 change_table(0, ipsrc);
948 authpf_kill_states();
951 if (pidfile[0] && pidfd != -1)
952 if (unlink(pidfile) == -1)
953 syslog(LOG_ERR, "cannot unlink %s (%m)", pidfile);