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.
18 * $FreeBSD: head/contrib/pf/authpf/authpf.c 223637 2011-06-28 11:57:25Z bz $
21 #include <sys/param.h>
22 #include <sys/types.h>
24 #include <sys/ioctl.h>
25 #include <sys/socket.h>
31 #include <net/pf/pfvar.h>
32 #include <arpa/inet.h>
36 #include <login_cap.h>
45 #include "pathnames.h"
47 #define __dead __dead2
49 static int read_config(FILE *);
50 static void print_message(const char *);
51 static int allowed_luser(const char *);
52 static int check_luser(const char *, const char *);
53 static int remove_stale_rulesets(void);
54 static int change_filter(int, const char *, const char *);
55 static int change_table(int, const char *);
56 static void authpf_kill_states(void);
58 int dev_fd
; /* pf device */
59 char anchorname
[PF_ANCHOR_NAME_SIZE
] = "authpf";
60 char rulesetname
[MAXPATHLEN
- PF_ANCHOR_NAME_SIZE
- 2];
61 char tablename
[PF_TABLE_NAME_SIZE
] = "authpf_users";
64 char luser
[MAXLOGNAME
]; /* username */
65 char ipsrc
[256]; /* ip as a string */
66 char pidfile
[MAXPATHLEN
]; /* we save pid in this file. */
68 struct timeval Tstart
, Tend
; /* start and end times of session */
70 volatile sig_atomic_t want_death
;
71 static void need_death(int signo
);
72 static __dead
void do_death(int);
75 * User shell for authenticating gateways. Sole purpose is to allow
76 * a user to ssh to a gateway, and have the gateway modify packet
77 * filters to allow access, then remove access when the user finishes
78 * up. Meant to be used only from ssh(1) connections.
81 main(int argc __unused
, char **argv __unused
)
83 int lockcnt
= 0, n
, pidfd
;
93 config
= fopen(PATH_CONFFILE
, "r");
95 syslog(LOG_ERR
, "cannot open %s (%m)", PATH_CONFFILE
);
99 if ((cp
= getenv("SSH_TTY")) == NULL
) {
100 syslog(LOG_ERR
, "non-interactive session connection for authpf");
104 if ((cp
= getenv("SSH_CLIENT")) == NULL
) {
105 syslog(LOG_ERR
, "cannot determine connection source");
109 if (strlcpy(ipsrc
, cp
, sizeof(ipsrc
)) >= sizeof(ipsrc
)) {
110 syslog(LOG_ERR
, "SSH_CLIENT variable too long");
113 cp
= strchr(ipsrc
, ' ');
115 syslog(LOG_ERR
, "corrupt SSH_CLIENT variable %s", ipsrc
);
119 if (inet_pton(AF_INET
, ipsrc
, &ina
) != 1 &&
120 inet_pton(AF_INET6
, ipsrc
, &ina
) != 1) {
122 "cannot determine IP from SSH_CLIENT %s", ipsrc
);
125 /* open the pf device */
126 dev_fd
= open(PATH_DEVFILE
, O_RDWR
);
128 syslog(LOG_ERR
, "cannot open packet filter device (%m)");
135 syslog(LOG_ERR
, "cannot find user for uid %u", uid
);
139 if ((lc
= login_getclass(pw
->pw_class
)) != NULL
)
140 shell
= login_getcapstr(lc
, "shell", pw
->pw_shell
,
143 shell
= pw
->pw_shell
;
147 if (strcmp(shell
, PATH_AUTHPF_SHELL
)) {
148 syslog(LOG_ERR
, "wrong shell for user %s, uid %u",
149 pw
->pw_name
, pw
->pw_uid
);
157 * Paranoia, but this data _does_ come from outside authpf, and
158 * truncation would be bad.
160 if (strlcpy(luser
, pw
->pw_name
, sizeof(luser
)) >= sizeof(luser
)) {
161 syslog(LOG_ERR
, "username too long: %s", pw
->pw_name
);
165 if ((n
= snprintf(rulesetname
, sizeof(rulesetname
), "%s(%ld)",
166 luser
, (long)getpid())) < 0 || (u_int
)n
>= sizeof(rulesetname
)) {
167 syslog(LOG_INFO
, "%s(%ld) too large, ruleset name will be %ld",
168 luser
, (long)getpid(), (long)getpid());
169 if ((n
= snprintf(rulesetname
, sizeof(rulesetname
), "%ld",
170 (long)getpid())) < 0 || (u_int
)n
>= sizeof(rulesetname
)) {
171 syslog(LOG_ERR
, "pid too large for ruleset name");
177 /* Make our entry in /var/authpf as /var/authpf/ipaddr */
178 n
= snprintf(pidfile
, sizeof(pidfile
), "%s/%s", PATH_PIDFILE
, ipsrc
);
179 if (n
< 0 || (u_int
)n
>= sizeof(pidfile
)) {
180 syslog(LOG_ERR
, "path to pidfile too long");
185 * If someone else is already using this ip, then this person
186 * wants to switch users - so kill the old process and exit
189 * Note, we could print a message and tell them to log out, but the
190 * usual case of this is that someone has left themselves logged in,
191 * with the authenticated connection iconized and someone else walks
192 * up to use and automatically logs in before using. If this just
193 * gets rid of the old one silently, the new user never knows they
194 * could have used someone else's old authentication. If we
195 * tell them to log out before switching users it is an invitation
200 int save_errno
, otherpid
= -1;
201 char otherluser
[MAXLOGNAME
];
203 if ((pidfd
= open(pidfile
, O_RDWR
|O_CREAT
, 0644)) == -1 ||
204 (pidfp
= fdopen(pidfd
, "r+")) == NULL
) {
207 syslog(LOG_ERR
, "cannot open or create %s: %s", pidfile
,
212 if (flock(fileno(pidfp
), LOCK_EX
|LOCK_NB
) == 0)
216 /* Mark our pid, and username to our file. */
219 /* 31 == MAXLOGNAME - 1 */
220 if (fscanf(pidfp
, "%d\n%31s\n", &otherpid
, otherluser
) != 2)
222 syslog(LOG_DEBUG
, "tried to lock %s, in use by pid %d: %s",
223 pidfile
, otherpid
, strerror(save_errno
));
227 "killing prior auth (pid %d) of %s by user %s",
228 otherpid
, ipsrc
, otherluser
);
229 if (kill((pid_t
) otherpid
, SIGTERM
) == -1) {
231 "could not kill process %d: (%m)",
237 * We try to kill the previous process and acquire the lock
238 * for 10 seconds, trying once a second. if we can't after
239 * 10 attempts we log an error and give up.
241 if (++lockcnt
> 10) {
242 syslog(LOG_ERR
, "cannot kill previous authpf (pid %d)",
250 /* re-open, and try again. The previous authpf process
251 * we killed above should unlink the file and release
252 * it's lock, giving us a chance to get it now
258 /* whack the group list */
260 if (setgroups(1, &gid
) == -1) {
261 syslog(LOG_INFO
, "setgroups: %s", strerror(errno
));
267 if (setresuid(uid
, uid
, uid
) == -1) {
268 syslog(LOG_INFO
, "setresuid: %s", strerror(errno
));
271 openlog("authpf", LOG_PID
| LOG_NDELAY
, LOG_DAEMON
);
273 if (!check_luser(PATH_BAN_DIR
, luser
) || !allowed_luser(luser
)) {
274 syslog(LOG_INFO
, "user %s prohibited", luser
);
278 if (read_config(config
)) {
279 syslog(LOG_ERR
, "invalid config file %s", PATH_CONFFILE
);
283 if (remove_stale_rulesets()) {
284 syslog(LOG_INFO
, "error removing stale rulesets");
288 /* We appear to be making headway, so actually mark our pid */
290 fprintf(pidfp
, "%ld\n%s\n", (long)getpid(), luser
);
292 ftruncate(fileno(pidfp
), ftell(pidfp
));
294 if (change_filter(1, luser
, ipsrc
) == -1) {
295 printf("Unable to modify filters\r\n");
298 if (change_table(1, ipsrc
) == -1) {
299 printf("Unable to modify table\r\n");
300 change_filter(0, luser
, ipsrc
);
304 signal(SIGTERM
, need_death
);
305 signal(SIGINT
, need_death
);
306 signal(SIGALRM
, need_death
);
307 signal(SIGPIPE
, need_death
);
308 signal(SIGHUP
, need_death
);
309 signal(SIGQUIT
, need_death
);
310 signal(SIGTSTP
, need_death
);
312 printf("\r\nHello %s. ", luser
);
313 printf("You are authenticated from host \"%s\"\r\n", ipsrc
);
314 setproctitle("%s@%s", luser
, ipsrc
);
315 print_message(PATH_MESSAGE
);
325 printf("\r\n\r\nSorry, this service is currently unavailable due to ");
326 printf("technical difficulties\r\n\r\n");
327 print_message(PATH_PROBLEM
);
328 printf("\r\nYour authentication process (pid %ld) was unable to run\n",
330 sleep(180); /* them lusers read reaaaaal slow */
336 * reads config file in PATH_CONFFILE to set optional behaviours up
346 char *pair
[4], *cp
, *tp
;
349 if (fgets(buf
, sizeof(buf
), f
) == NULL
) {
357 if (buf
[len
- 1] != '\n' && !feof(f
)) {
358 syslog(LOG_ERR
, "line %d too long in %s", i
,
364 for (cp
= buf
; *cp
== ' ' || *cp
== '\t'; cp
++)
367 if (!*cp
|| *cp
== '#' || *cp
== '\n')
370 for (ap
= pair
; ap
< &pair
[3] &&
371 (*ap
= strsep(&cp
, "=")) != NULL
; ) {
378 tp
= pair
[1] + strlen(pair
[1]);
379 while ((*tp
== ' ' || *tp
== '\t') && tp
>= pair
[1])
382 if (strcasecmp(pair
[0], "anchor") == 0) {
383 if (!pair
[1][0] || strlcpy(anchorname
, pair
[1],
384 sizeof(anchorname
)) >= sizeof(anchorname
))
387 if (strcasecmp(pair
[0], "table") == 0) {
388 if (!pair
[1][0] || strlcpy(tablename
, pair
[1],
389 sizeof(tablename
)) >= sizeof(tablename
))
392 } while (!feof(f
) && !ferror(f
));
398 syslog(LOG_ERR
, "parse error, line %d of %s", i
, PATH_CONFFILE
);
404 * splatter a file to stdout - max line length of 1024,
405 * used for spitting message files at users to tell them
406 * they've been bad or we're unavailable.
409 print_message(const char *filename
)
414 if ((f
= fopen(filename
, "r")) == NULL
)
415 return; /* fail silently, we don't care if it isn't there */
418 if (fgets(buf
, sizeof(buf
), f
) == NULL
) {
423 } while (fputs(buf
, stdout
) != EOF
&& !feof(f
));
429 * allowed_luser checks to see if user "luser" is allowed to
430 * use this gateway by virtue of being listed in an allowed
431 * users file, namely /etc/authpf/authpf.allow .
433 * If /etc/authpf/authpf.allow does not exist, then we assume that
434 * all users who are allowed in by sshd(8) are permitted to
435 * use this gateway. If /etc/authpf/authpf.allow does exist, then a
436 * user must be listed if the connection is to continue, else
437 * the session terminates in the same manner as being banned.
440 allowed_luser(const char *user
)
447 if ((f
= fopen(PATH_ALLOWFILE
, "r")) == NULL
) {
448 if (errno
== ENOENT
) {
450 * allowfile doesn't exist, thus this gateway
451 * isn't restricted to certain users...
457 * user may in fact be allowed, but we can't open
458 * the file even though it's there. probably a config
461 syslog(LOG_ERR
, "cannot open allowed users file %s (%s)",
462 PATH_ALLOWFILE
, strerror(errno
));
466 * /etc/authpf/authpf.allow exists, thus we do a linear
467 * search to see if they are allowed.
468 * also, if username "*" exists, then this is a
469 * "public" gateway, such as it is, so let
473 while ((buf
= fgetln(f
, &len
))) {
474 if (buf
[len
- 1] == '\n')
477 if ((lbuf
= (char *)malloc(len
+ 1)) == NULL
)
479 memcpy(lbuf
, buf
, len
);
484 matched
= strcmp(user
, buf
) == 0 || strcmp("*", buf
) == 0;
492 return (1); /* matched an allowed username */
494 syslog(LOG_INFO
, "denied access to %s: not listed in %s",
495 user
, PATH_ALLOWFILE
);
497 fputs("\n\nSorry, you are not allowed to use this facility!\n",
505 * check_luser checks to see if user "luser" has been banned
506 * from using us by virtue of having an file of the same name
507 * in the "luserdir" directory.
509 * If the user has been banned, we copy the contents of the file
510 * to the user's screen. (useful for telling the user what to
511 * do to get un-banned, or just to tell them they aren't
512 * going to be un-banned.)
515 check_luser(const char *userdir
, const char *user
)
519 char tmp
[MAXPATHLEN
];
521 n
= snprintf(tmp
, sizeof(tmp
), "%s/%s", userdir
, user
);
522 if (n
< 0 || (u_int
)n
>= sizeof(tmp
)) {
523 syslog(LOG_ERR
, "provided banned directory line too long (%s)",
527 if ((f
= fopen(tmp
, "r")) == NULL
) {
528 if (errno
== ENOENT
) {
530 * file or dir doesn't exist, so therefore
531 * this luser isn't banned.. all is well
536 * user may in fact be banned, but we can't open the
537 * file even though it's there. probably a config
540 syslog(LOG_ERR
, "cannot open banned file %s (%s)",
541 tmp
, strerror(errno
));
546 * user is banned - spit the file at them to
547 * tell what they can do and where they can go.
549 syslog(LOG_INFO
, "denied access to %s: %s exists",
553 strlcpy(tmp
, "\n\n-**- Sorry, you have been banned! -**-\n\n",
555 while (fputs(tmp
, stdout
) != EOF
&& !feof(f
)) {
556 if (fgets(tmp
, sizeof(tmp
), f
) == NULL
) {
569 * Search for rulesets left by other authpf processes (either because they
570 * died ungracefully or were terminated) and remove them.
573 remove_stale_rulesets(void)
575 struct pfioc_ruleset prs
;
578 memset(&prs
, 0, sizeof(prs
));
579 strlcpy(prs
.path
, anchorname
, sizeof(prs
.path
));
580 if (ioctl(dev_fd
, DIOCGETRULESETS
, &prs
)) {
594 if (ioctl(dev_fd
, DIOCGETRULESET
, &prs
))
597 if ((t
= strchr(prs
.name
, '(')) == NULL
)
601 pid
= strtoul(t
, &s
, 10);
602 if (!prs
.name
[0] || errno
||
603 (*s
&& (t
== prs
.name
|| *s
!= ')')))
605 if (kill(pid
, 0) && errno
!= EPERM
) {
607 struct pfioc_trans_e t_e
[PF_RULESET_MAX
+1];
608 struct pfioc_trans t_local
;
610 bzero(&t
, sizeof(t_local
));
611 bzero(t_e
, sizeof(t_e
));
612 t_local
.size
= PF_RULESET_MAX
+1;
613 t_local
.esize
= sizeof(t_e
[0]);
615 for (i
= 0; i
< PF_RULESET_MAX
+1; ++i
) {
617 snprintf(t_e
[i
].anchor
, sizeof(t_e
[i
].anchor
),
618 "%s/%s", anchorname
, prs
.name
);
628 * Add/remove filter entries for user "luser" from ip "ipsrc"
631 change_filter(int add
, const char *user
, const char *his_ipsrc
)
633 const char *pargv
[13] = {
634 "pfctl", "-p", "/dev/pf", "-q", "-a", "anchor/ruleset",
635 "-D", "user_ip=X", "-D", "user_id=X", "-f",
638 char *fdpath
= NULL
, *userstr
= NULL
, *ipstr
= NULL
;
639 char *rsn
= NULL
, *fn
= NULL
;
644 if (user
== NULL
|| !user
[0] || his_ipsrc
== NULL
|| !his_ipsrc
[0]) {
645 syslog(LOG_ERR
, "invalid user/ipsrc");
649 if (asprintf(&rsn
, "%s/%s", anchorname
, rulesetname
) == -1)
651 if (asprintf(&fdpath
, "/dev/fd/%d", dev_fd
) == -1)
653 if (asprintf(&ipstr
, "user_ip=%s", his_ipsrc
) == -1)
655 if (asprintf(&userstr
, "user_id=%s", user
) == -1)
661 if (asprintf(&fn
, "%s/%s/authpf.rules", PATH_USER_DIR
, user
)
664 if (stat(fn
, &sb
) == -1) {
666 if ((fn
= strdup(PATH_PFRULES
)) == NULL
)
675 pargv
[11] = "/dev/null";
679 switch (pid
= fork()) {
681 syslog(LOG_ERR
, "fork failed");
684 /* revoke group privs before exec */
686 if (setregid(gid
, gid
) == -1) {
689 execvp(PATH_PFCTL
, __DECONST(char *const *, pargv
));
690 warn("exec of %s failed", PATH_PFCTL
);
697 syslog(LOG_ERR
, "pfctl exited abnormally");
702 gettimeofday(&Tstart
, NULL
);
703 syslog(LOG_INFO
, "allowing %s, user %s", his_ipsrc
, user
);
705 gettimeofday(&Tend
, NULL
);
706 syslog(LOG_INFO
, "removed %s, user %s - duration %ld seconds",
707 his_ipsrc
, user
, Tend
.tv_sec
- Tstart
.tv_sec
);
711 syslog(LOG_ERR
, "malloc failed");
722 * Add/remove this IP from the "authpf_users" table.
725 change_table(int add
, const char *his_ipsrc
)
727 struct pfioc_table io
;
728 struct pfr_addr addr
;
730 bzero(&io
, sizeof(io
));
731 strlcpy(io
.pfrio_table
.pfrt_name
, tablename
,
732 sizeof(io
.pfrio_table
.pfrt_name
));
733 io
.pfrio_buffer
= &addr
;
734 io
.pfrio_esize
= sizeof(addr
);
737 bzero(&addr
, sizeof(addr
));
738 if (his_ipsrc
== NULL
|| !his_ipsrc
[0])
740 if (inet_pton(AF_INET
, his_ipsrc
, &addr
.pfra_ip4addr
) == 1) {
741 addr
.pfra_af
= AF_INET
;
743 } else if (inet_pton(AF_INET6
, his_ipsrc
, &addr
.pfra_ip6addr
) == 1) {
744 addr
.pfra_af
= AF_INET6
;
747 syslog(LOG_ERR
, "invalid his_ipsrc");
751 if (ioctl(dev_fd
, add
? DIOCRADDADDRS
: DIOCRDELADDRS
, &io
) &&
753 syslog(LOG_ERR
, "cannot %s %s from table %s: %s",
754 add
? "add" : "remove", his_ipsrc
, tablename
,
762 * This is to kill off states that would otherwise be left behind stateful
763 * rules. This means we don't need to allow in more traffic than we really
764 * want to, since we don't have to worry about any luser sessions lasting
765 * longer than their ssh session. This function is based on
766 * pfctl_kill_states from pfctl.
769 authpf_kill_states(void)
771 struct pfioc_state_kill psk
;
772 struct pf_addr target
;
774 memset(&psk
, 0, sizeof(psk
));
775 memset(&target
, 0, sizeof(target
));
777 if (inet_pton(AF_INET
, ipsrc
, &target
.v4
) == 1)
778 psk
.psk_af
= AF_INET
;
779 else if (inet_pton(AF_INET6
, ipsrc
, &target
.v6
) == 1)
780 psk
.psk_af
= AF_INET6
;
782 syslog(LOG_ERR
, "inet_pton(%s) failed", ipsrc
);
786 /* Kill all states from ipsrc */
787 memcpy(&psk
.psk_src
.addr
.v
.a
.addr
, &target
,
788 sizeof(psk
.psk_src
.addr
.v
.a
.addr
));
789 memset(&psk
.psk_src
.addr
.v
.a
.mask
, 0xff,
790 sizeof(psk
.psk_src
.addr
.v
.a
.mask
));
791 if (ioctl(dev_fd
, DIOCKILLSTATES
, &psk
))
792 syslog(LOG_ERR
, "DIOCKILLSTATES failed (%m)");
794 /* Kill all states to ipsrc */
795 memset(&psk
.psk_src
, 0, sizeof(psk
.psk_src
));
796 memcpy(&psk
.psk_dst
.addr
.v
.a
.addr
, &target
,
797 sizeof(psk
.psk_dst
.addr
.v
.a
.addr
));
798 memset(&psk
.psk_dst
.addr
.v
.a
.mask
, 0xff,
799 sizeof(psk
.psk_dst
.addr
.v
.a
.mask
));
800 if (ioctl(dev_fd
, DIOCKILLSTATES
, &psk
))
801 syslog(LOG_ERR
, "DIOCKILLSTATES failed (%m)");
804 /* signal handler that makes us go away properly */
806 need_death(int signo __unused
)
812 * function that removes our stuff when we go away.
820 change_filter(0, luser
, ipsrc
);
821 change_table(0, ipsrc
);
822 authpf_kill_states();
823 remove_stale_rulesets();
825 if (pidfile
[0] && (pidfp
!= NULL
))
826 if (unlink(pidfile
) == -1)
827 syslog(LOG_ERR
, "cannot unlink %s (%m)", pidfile
);