1 /* $OpenBSD: authpf.c,v 1.104 2007/02/24 17:35:08 beck Exp $ */
2 /* $DragonFly: src/usr.sbin/authpf/authpf.c,v 1.2 2004/12/18 22:48:02 swildner Exp $ */
5 * Copyright (C) 1998 - 2007 Bob Beck (beck@openbsd.org).
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/param.h>
30 #include <sys/types.h>
32 #include <sys/ioctl.h>
33 #include <sys/socket.h>
39 #include <net/pf/pfvar.h>
40 #include <arpa/inet.h>
44 #include <login_cap.h>
53 #include "pathnames.h"
55 #define __dead __dead2
57 static int read_config(FILE *);
58 static void print_message(const char *);
59 static int allowed_luser(const char *);
60 static int check_luser(const char *, const char *);
61 static int remove_stale_rulesets(void);
62 static int change_filter(int, const char *, const char *);
63 static int change_table(int, const char *);
64 static void authpf_kill_states(void);
66 int dev_fd
; /* pf device */
67 char anchorname
[PF_ANCHOR_NAME_SIZE
] = "authpf";
68 char rulesetname
[MAXPATHLEN
- PF_ANCHOR_NAME_SIZE
- 2];
69 char tablename
[PF_TABLE_NAME_SIZE
] = "authpf_users";
72 char luser
[MAXLOGNAME
]; /* username */
73 char ipsrc
[256]; /* ip as a string */
74 char pidfile
[MAXPATHLEN
]; /* we save pid in this file. */
76 struct timeval Tstart
, Tend
; /* start and end times of session */
78 volatile sig_atomic_t want_death
;
79 static void need_death(int signo
);
80 static __dead
void do_death(int);
83 * User shell for authenticating gateways. Sole purpose is to allow
84 * a user to ssh to a gateway, and have the gateway modify packet
85 * filters to allow access, then remove access when the user finishes
86 * up. Meant to be used only from ssh(1) connections.
89 main(int argc __unused
, char **argv __unused
)
91 int lockcnt
= 0, n
, pidfd
;
101 config
= fopen(PATH_CONFFILE
, "r");
102 if (config
== NULL
) {
103 syslog(LOG_ERR
, "can not open %s (%m)", PATH_CONFFILE
);
107 if ((cp
= getenv("SSH_TTY")) == NULL
) {
108 syslog(LOG_ERR
, "non-interactive session connection for authpf");
112 if ((cp
= getenv("SSH_CLIENT")) == NULL
) {
113 syslog(LOG_ERR
, "cannot determine connection source");
117 if (strlcpy(ipsrc
, cp
, sizeof(ipsrc
)) >= sizeof(ipsrc
)) {
118 syslog(LOG_ERR
, "SSH_CLIENT variable too long");
121 cp
= strchr(ipsrc
, ' ');
123 syslog(LOG_ERR
, "corrupt SSH_CLIENT variable %s", ipsrc
);
127 if (inet_pton(AF_INET
, ipsrc
, &ina
) != 1 &&
128 inet_pton(AF_INET6
, ipsrc
, &ina
) != 1) {
130 "cannot determine IP from SSH_CLIENT %s", ipsrc
);
133 /* open the pf device */
134 dev_fd
= open(PATH_DEVFILE
, O_RDWR
);
136 syslog(LOG_ERR
, "cannot open packet filter device (%m)");
143 syslog(LOG_ERR
, "cannot find user for uid %u", uid
);
147 if ((lc
= login_getclass(pw
->pw_class
)) != NULL
)
148 shell
= login_getcapstr(lc
, "shell", pw
->pw_shell
,
151 shell
= pw
->pw_shell
;
155 if (strcmp(shell
, PATH_AUTHPF_SHELL
)) {
156 syslog(LOG_ERR
, "wrong shell for user %s, uid %u",
157 pw
->pw_name
, pw
->pw_uid
);
158 if (shell
!= pw
->pw_shell
)
163 if (shell
!= pw
->pw_shell
)
167 * Paranoia, but this data _does_ come from outside authpf, and
168 * truncation would be bad.
170 if (strlcpy(luser
, pw
->pw_name
, sizeof(luser
)) >= sizeof(luser
)) {
171 syslog(LOG_ERR
, "username too long: %s", pw
->pw_name
);
175 if ((n
= snprintf(rulesetname
, sizeof(rulesetname
), "%s(%ld)",
176 luser
, (long)getpid())) < 0 || n
>= (int)sizeof(rulesetname
)) {
177 syslog(LOG_INFO
, "%s(%ld) too large, ruleset name will be %ld",
178 luser
, (long)getpid(), (long)getpid());
179 if ((n
= snprintf(rulesetname
, sizeof(rulesetname
), "%ld",
180 (long)getpid())) < 0 || n
>= (int)sizeof(rulesetname
)) {
181 syslog(LOG_ERR
, "pid too large for ruleset name");
187 /* Make our entry in /var/authpf as /var/authpf/ipaddr */
188 n
= snprintf(pidfile
, sizeof(pidfile
), "%s/%s", PATH_PIDFILE
, ipsrc
);
189 if (n
< 0 || (u_int
)n
>= sizeof(pidfile
)) {
190 syslog(LOG_ERR
, "path to pidfile too long");
195 * If someone else is already using this ip, then this person
196 * wants to switch users - so kill the old process and exit
199 * Note, we could print a message and tell them to log out, but the
200 * usual case of this is that someone has left themselves logged in,
201 * with the authenticated connection iconized and someone else walks
202 * up to use and automatically logs in before using. If this just
203 * gets rid of the old one silently, the new user never knows they
204 * could have used someone else's old authentication. If we
205 * tell them to log out before switching users it is an invitation
210 int save_errno
, otherpid
= -1;
211 char otherluser
[MAXLOGNAME
];
213 if ((pidfd
= open(pidfile
, O_RDWR
|O_CREAT
, 0644)) == -1 ||
214 (pidfp
= fdopen(pidfd
, "r+")) == NULL
) {
217 syslog(LOG_ERR
, "cannot open or create %s: %s", pidfile
,
222 if (flock(fileno(pidfp
), LOCK_EX
|LOCK_NB
) == 0)
226 /* Mark our pid, and username to our file. */
229 /* 31 == MAXLOGNAME - 1 */
230 if (fscanf(pidfp
, "%d\n%31s\n", &otherpid
, otherluser
) != 2)
232 syslog(LOG_DEBUG
, "tried to lock %s, in use by pid %d: %s",
233 pidfile
, otherpid
, strerror(save_errno
));
237 "killing prior auth (pid %d) of %s by user %s",
238 otherpid
, ipsrc
, otherluser
);
239 if (kill((pid_t
) otherpid
, SIGTERM
) == -1) {
241 "could not kill process %d: (%m)",
247 * we try to kill the previous process and acquire the lock
248 * for 10 seconds, trying once a second. if we can't after
249 * 10 attempts we log an error and give up
251 if (++lockcnt
> 10) {
252 syslog(LOG_ERR
, "cannot kill previous authpf (pid %d)",
260 /* re-open, and try again. The previous authpf process
261 * we killed above should unlink the file and release
262 * it's lock, giving us a chance to get it now
268 /* whack the group list */
270 if (setgroups(1, &gid
) == -1) {
271 syslog(LOG_INFO
, "setgroups: %s", strerror(errno
));
277 if (setresuid(uid
, uid
, uid
) == -1) {
278 syslog(LOG_INFO
, "setresuid: %s", strerror(errno
));
281 openlog("authpf", LOG_PID
| LOG_NDELAY
, LOG_DAEMON
);
283 if (!check_luser(PATH_BAN_DIR
, luser
) || !allowed_luser(luser
)) {
284 syslog(LOG_INFO
, "user %s prohibited", luser
);
288 if (read_config(config
)) {
289 syslog(LOG_ERR
, "invalid config file %s", PATH_CONFFILE
);
293 if (remove_stale_rulesets()) {
294 syslog(LOG_INFO
, "error removing stale rulesets");
298 /* We appear to be making headway, so actually mark our pid */
300 fprintf(pidfp
, "%ld\n%s\n", (long)getpid(), luser
);
302 ftruncate(fileno(pidfp
), ftell(pidfp
));
304 if (change_filter(1, luser
, ipsrc
) == -1) {
305 printf("Unable to modify filters\r\n");
308 if (change_table(1, ipsrc
) == -1) {
309 printf("Unable to modify table\r\n");
310 change_filter(0, luser
, ipsrc
);
314 signal(SIGTERM
, need_death
);
315 signal(SIGINT
, need_death
);
316 signal(SIGALRM
, need_death
);
317 signal(SIGPIPE
, need_death
);
318 signal(SIGHUP
, need_death
);
319 signal(SIGQUIT
, need_death
);
320 signal(SIGTSTP
, need_death
);
322 printf("\r\nHello %s. ", luser
);
323 printf("You are authenticated from host \"%s\"\r\n", ipsrc
);
324 setproctitle("%s@%s", luser
, ipsrc
);
325 print_message(PATH_MESSAGE
);
335 printf("\r\n\r\nSorry, this service is currently unavailable due to ");
336 printf("technical difficulties\r\n\r\n");
337 print_message(PATH_PROBLEM
);
338 printf("\r\nYour authentication process (pid %ld) was unable to run\n",
340 sleep(180); /* them lusers read reaaaaal slow */
346 * reads config file in PATH_CONFFILE to set optional behaviours up
356 char *pair
[4], *cp
, *tp
;
359 if (fgets(buf
, sizeof(buf
), f
) == NULL
) {
365 if (buf
[len
- 1] != '\n' && !feof(f
)) {
366 syslog(LOG_ERR
, "line %d too long in %s", i
,
372 for (cp
= buf
; *cp
== ' ' || *cp
== '\t'; cp
++)
375 if (!*cp
|| *cp
== '#' || *cp
== '\n')
378 for (ap
= pair
; ap
< &pair
[3] &&
379 (*ap
= strsep(&cp
, "=")) != NULL
; ) {
386 tp
= pair
[1] + strlen(pair
[1]);
387 while ((*tp
== ' ' || *tp
== '\t') && tp
>= pair
[1])
390 if (strcasecmp(pair
[0], "anchor") == 0) {
391 if (!pair
[1][0] || strlcpy(anchorname
, pair
[1],
392 sizeof(anchorname
)) >= sizeof(anchorname
))
395 if (strcasecmp(pair
[0], "table") == 0) {
396 if (!pair
[1][0] || strlcpy(tablename
, pair
[1],
397 sizeof(tablename
)) >= sizeof(tablename
))
400 } while (!feof(f
) && !ferror(f
));
406 syslog(LOG_ERR
, "parse error, line %d of %s", i
, PATH_CONFFILE
);
412 * splatter a file to stdout - max line length of 1024,
413 * used for spitting message files at users to tell them
414 * they've been bad or we're unavailable.
417 print_message(const char *filename
)
422 if ((f
= fopen(filename
, "r")) == NULL
)
423 return; /* fail silently, we don't care if it isn't there */
426 if (fgets(buf
, sizeof(buf
), f
) == NULL
) {
431 } while (fputs(buf
, stdout
) != EOF
&& !feof(f
));
437 * allowed_luser checks to see if user "luser" is allowed to
438 * use this gateway by virtue of being listed in an allowed
439 * users file, namely /etc/authpf/authpf.allow .
441 * If /etc/authpf/authpf.allow does not exist, then we assume that
442 * all users who are allowed in by sshd(8) are permitted to
443 * use this gateway. If /etc/authpf/authpf.allow does exist, then a
444 * user must be listed if the connection is to continue, else
445 * the session terminates in the same manner as being banned.
448 allowed_luser(const char *user
)
455 if ((f
= fopen(PATH_ALLOWFILE
, "r")) == NULL
) {
456 if (errno
== ENOENT
) {
458 * allowfile doesn't exist, thus this gateway
459 * isn't restricted to certain users...
465 * user may in fact be allowed, but we can't open
466 * the file even though it's there. probably a config
469 syslog(LOG_ERR
, "cannot open allowed users file %s (%s)",
470 PATH_ALLOWFILE
, strerror(errno
));
474 * /etc/authpf/authpf.allow exists, thus we do a linear
475 * search to see if they are allowed.
476 * also, if username "*" exists, then this is a
477 * "public" gateway, such as it is, so let
481 while ((buf
= fgetln(f
, &len
))) {
482 if (buf
[len
- 1] == '\n')
485 if ((lbuf
= (char *)malloc(len
+ 1)) == NULL
)
487 memcpy(lbuf
, buf
, len
);
492 matched
= strcmp(user
, buf
) == 0 || strcmp("*", buf
) == 0;
500 return (1); /* matched an allowed username */
502 syslog(LOG_INFO
, "denied access to %s: not listed in %s",
503 user
, PATH_ALLOWFILE
);
505 fputs("\n\nSorry, you are not allowed to use this facility!\n",
513 * check_luser checks to see if user "luser" has been banned
514 * from using us by virtue of having an file of the same name
515 * in the "luserdir" directory.
517 * If the user has been banned, we copy the contents of the file
518 * to the user's screen. (useful for telling the user what to
519 * do to get un-banned, or just to tell them they aren't
520 * going to be un-banned.)
523 check_luser(const char *userdir
, const char *user
)
527 char tmp
[MAXPATHLEN
];
529 n
= snprintf(tmp
, sizeof(tmp
), "%s/%s", userdir
, user
);
530 if (n
< 0 || (u_int
)n
>= sizeof(tmp
)) {
531 syslog(LOG_ERR
, "provided banned directory line too long (%s)",
535 if ((f
= fopen(tmp
, "r")) == NULL
) {
536 if (errno
== ENOENT
) {
538 * file or dir doesn't exist, so therefore
539 * this luser isn't banned.. all is well
544 * user may in fact be banned, but we can't open the
545 * file even though it's there. probably a config
548 syslog(LOG_ERR
, "cannot open banned file %s (%s)",
549 tmp
, strerror(errno
));
554 * user is banned - spit the file at them to
555 * tell what they can do and where they can go.
557 syslog(LOG_INFO
, "denied access to %s: %s exists",
561 strlcpy(tmp
, "\n\n-**- Sorry, you have been banned! -**-\n\n",
563 while (fputs(tmp
, stdout
) != EOF
&& !feof(f
)) {
564 if (fgets(tmp
, sizeof(tmp
), f
) == NULL
) {
577 * Search for rulesets left by other authpf processes (either because they
578 * died ungracefully or were terminated) and remove them.
581 remove_stale_rulesets(void)
583 struct pfioc_ruleset prs
;
586 memset(&prs
, 0, sizeof(prs
));
587 strlcpy(prs
.path
, anchorname
, sizeof(prs
.path
));
588 if (ioctl(dev_fd
, DIOCGETRULESETS
, &prs
)) {
602 if (ioctl(dev_fd
, DIOCGETRULESET
, &prs
))
605 if ((t
= strchr(prs
.name
, '(')) == NULL
)
609 pid
= strtoul(t
, &s
, 10);
610 if (!prs
.name
[0] || errno
||
611 (*s
&& (t
== prs
.name
|| *s
!= ')')))
613 if (kill(pid
, 0) && errno
!= EPERM
) {
615 struct pfioc_trans_e t_e
[PF_RULESET_MAX
+1];
616 struct pfioc_trans t_local
;
618 bzero(&t
, sizeof(t_local
));
619 bzero(t_e
, sizeof(t_e
));
620 t_local
.size
= PF_RULESET_MAX
+1;
621 t_local
.esize
= sizeof(t_e
[0]);
623 for (i
= 0; i
< PF_RULESET_MAX
+1; ++i
) {
625 snprintf(t_e
[i
].anchor
, sizeof(t_e
[i
].anchor
),
626 "%s/%s", anchorname
, prs
.name
);
636 * Add/remove filter entries for user "luser" from ip "ipsrc"
639 change_filter(int add
, const char *user
, const char *his_ipsrc
)
641 const char *pargv
[13] = {
642 "pfctl", "-p", "/dev/pf", "-q", "-a", "anchor/ruleset",
643 "-D", "user_ip=X", "-D", "user_id=X", "-f",
646 char *fdpath
= NULL
, *userstr
= NULL
, *ipstr
= NULL
;
647 char *rsn
= NULL
, *fn
= NULL
;
652 if (user
== NULL
|| !user
[0] || his_ipsrc
== NULL
|| !his_ipsrc
[0]) {
653 syslog(LOG_ERR
, "invalid user/ipsrc");
657 if (asprintf(&rsn
, "%s/%s", anchorname
, rulesetname
) == -1)
659 if (asprintf(&fdpath
, "/dev/fd/%d", dev_fd
) == -1)
661 if (asprintf(&ipstr
, "user_ip=%s", his_ipsrc
) == -1)
663 if (asprintf(&userstr
, "user_id=%s", user
) == -1)
669 if (asprintf(&fn
, "%s/%s/authpf.rules", PATH_USER_DIR
, user
)
672 if (stat(fn
, &sb
) == -1) {
674 if ((fn
= strdup(PATH_PFRULES
)) == NULL
)
683 pargv
[11] = "/dev/null";
687 switch (pid
= fork()) {
689 syslog(LOG_ERR
, "fork failed");
692 /* revoke group privs before exec */
694 if (setregid(gid
, gid
) == -1) {
697 execvp(PATH_PFCTL
, __DECONST(char *const *, pargv
));
698 warn("exec of %s failed", PATH_PFCTL
);
705 syslog(LOG_ERR
, "pfctl exited abnormally");
710 gettimeofday(&Tstart
, NULL
);
711 syslog(LOG_INFO
, "allowing %s, user %s", his_ipsrc
, user
);
713 gettimeofday(&Tend
, NULL
);
714 syslog(LOG_INFO
, "removed %s, user %s - duration %ld seconds",
715 his_ipsrc
, user
, Tend
.tv_sec
- Tstart
.tv_sec
);
719 syslog(LOG_ERR
, "malloc failed");
730 * Add/remove this IP from the "authpf_users" table.
733 change_table(int add
, const char *his_ipsrc
)
735 struct pfioc_table io
;
736 struct pfr_addr addr
;
738 bzero(&io
, sizeof(io
));
739 strlcpy(io
.pfrio_table
.pfrt_name
, tablename
,
740 sizeof(io
.pfrio_table
.pfrt_name
));
741 io
.pfrio_buffer
= &addr
;
742 io
.pfrio_esize
= sizeof(addr
);
745 bzero(&addr
, sizeof(addr
));
746 if (his_ipsrc
== NULL
|| !his_ipsrc
[0])
748 if (inet_pton(AF_INET
, his_ipsrc
, &addr
.pfra_ip4addr
) == 1) {
749 addr
.pfra_af
= AF_INET
;
751 } else if (inet_pton(AF_INET6
, his_ipsrc
, &addr
.pfra_ip6addr
) == 1) {
752 addr
.pfra_af
= AF_INET6
;
755 syslog(LOG_ERR
, "invalid his_ipsrc");
759 if (ioctl(dev_fd
, add
? DIOCRADDADDRS
: DIOCRDELADDRS
, &io
) &&
761 syslog(LOG_ERR
, "cannot %s %s from table %s: %s",
762 add
? "add" : "remove", his_ipsrc
, tablename
,
770 * This is to kill off states that would otherwise be left behind stateful
771 * rules. This means we don't need to allow in more traffic than we really
772 * want to, since we don't have to worry about any luser sessions lasting
773 * longer than their ssh session. This function is based on
774 * pfctl_kill_states from pfctl.
777 authpf_kill_states(void)
779 struct pfioc_state_kill psk
;
780 struct pf_addr target
;
782 memset(&psk
, 0, sizeof(psk
));
783 memset(&target
, 0, sizeof(target
));
785 if (inet_pton(AF_INET
, ipsrc
, &target
.v4
) == 1)
786 psk
.psk_af
= AF_INET
;
787 else if (inet_pton(AF_INET6
, ipsrc
, &target
.v6
) == 1)
788 psk
.psk_af
= AF_INET6
;
790 syslog(LOG_ERR
, "inet_pton(%s) failed", ipsrc
);
794 /* Kill all states from ipsrc */
795 memcpy(&psk
.psk_src
.addr
.v
.a
.addr
, &target
,
796 sizeof(psk
.psk_src
.addr
.v
.a
.addr
));
797 memset(&psk
.psk_src
.addr
.v
.a
.mask
, 0xff,
798 sizeof(psk
.psk_src
.addr
.v
.a
.mask
));
799 if (ioctl(dev_fd
, DIOCKILLSTATES
, &psk
))
800 syslog(LOG_ERR
, "DIOCKILLSTATES failed (%m)");
802 /* Kill all states to ipsrc */
803 memset(&psk
.psk_src
, 0, sizeof(psk
.psk_src
));
804 memcpy(&psk
.psk_dst
.addr
.v
.a
.addr
, &target
,
805 sizeof(psk
.psk_dst
.addr
.v
.a
.addr
));
806 memset(&psk
.psk_dst
.addr
.v
.a
.mask
, 0xff,
807 sizeof(psk
.psk_dst
.addr
.v
.a
.mask
));
808 if (ioctl(dev_fd
, DIOCKILLSTATES
, &psk
))
809 syslog(LOG_ERR
, "DIOCKILLSTATES failed (%m)");
812 /* signal handler that makes us go away properly */
814 need_death(int signo __unused
)
820 * function that removes our stuff when we go away.
828 change_filter(0, luser
, ipsrc
);
829 change_table(0, ipsrc
);
830 authpf_kill_states();
831 remove_stale_rulesets();
833 if (pidfile
[0] && (pidfp
!= NULL
))
834 if (unlink(pidfile
) == -1)
835 syslog(LOG_ERR
, "cannot unlink %s (%m)", pidfile
);