/*      $NetBSD: authpf.c,v 1.7 2008/12/29 04:13:28 christos Exp $      */
/*      $OpenBSD: authpf.c,v 1.104 2007/02/24 17:35:08 beck Exp $       */

/*
 * Copyright (C) 1998 - 2007 Bob Beck (beck@openbsd.org).
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <net/if.h>
#include <net/pfvar.h>
#include <arpa/inet.h>

#include <err.h>
#include <errno.h>
#include <login_cap.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "pathnames.h"

static int      read_config(FILE *);
static void     print_message(char *);
static int      allowed_luser(char *);
static int      check_luser(char *, char *);
static int      remove_stale_rulesets(void);
static int      change_filter(int, const char *, const char *);
static int      change_table(int, const char *);
static void     authpf_kill_states(void);

int     dev;                    /* pf device */
char    anchorname[PF_ANCHOR_NAME_SIZE] = "authpf";
char    rulesetname[MAXPATHLEN - PF_ANCHOR_NAME_SIZE - 2];
char    tablename[PF_TABLE_NAME_SIZE] = "authpf_users";

FILE    *pidfp;
char     luser[MAXLOGNAME];     /* username */
char     ipsrc[256];            /* ip as a string */
char     pidfile[MAXPATHLEN];   /* we save pid in this file. */

struct timeval  Tstart, Tend;   /* start and end times of session */

volatile sig_atomic_t   want_death;
static void             need_death(int signo);
static __dead void      do_death(int);

/*
 * User shell for authenticating gateways. Sole purpose is to allow
 * a user to ssh to a gateway, and have the gateway modify packet
 * filters to allow access, then remove access when the user finishes
 * up. Meant to be used only from ssh(1) connections.
 */
int
main(int argc, char *argv[])
{
        int              lockcnt = 0, n, pidfd;
        FILE            *config;
        struct in6_addr  ina;
        struct passwd   *pw;
        char            *cp;
        gid_t            gid;
        uid_t            uid;
        char            *shell;
        login_cap_t     *lc;

        config = fopen(PATH_CONFFILE, "r");
        if (config == NULL) {
                syslog(LOG_ERR, "can not open %s (%m)", PATH_CONFFILE);
                exit(1);
        }

        if ((cp = getenv("SSH_TTY")) == NULL) {
                syslog(LOG_ERR, "non-interactive session connection for authpf");
                exit(1);
        }

        if ((cp = getenv("SSH_CLIENT")) == NULL) {
                syslog(LOG_ERR, "cannot determine connection source");
                exit(1);
        }

        if (strlcpy(ipsrc, cp, sizeof(ipsrc)) >= sizeof(ipsrc)) {
                syslog(LOG_ERR, "SSH_CLIENT variable too long");
                exit(1);
        }
        cp = strchr(ipsrc, ' ');
        if (!cp) {
                syslog(LOG_ERR, "corrupt SSH_CLIENT variable %s", ipsrc);
                exit(1);
        }
        *cp = '\0';
        if (inet_pton(AF_INET, ipsrc, &ina) != 1 &&
            inet_pton(AF_INET6, ipsrc, &ina) != 1) {
                syslog(LOG_ERR,
                    "cannot determine IP from SSH_CLIENT %s", ipsrc);
                exit(1);
        }
        /* open the pf device */
        dev = open(PATH_DEVFILE, O_RDWR);
        if (dev == -1) {
                syslog(LOG_ERR, "cannot open packet filter device (%m)");
                goto die;
        }

        uid = getuid();
        pw = getpwuid(uid);
        if (pw == NULL) {
                syslog(LOG_ERR, "cannot find user for uid %u", uid);
                goto die;
        }

        if ((lc = login_getclass(pw->pw_class)) != NULL)
                shell = login_getcapstr(lc, "shell", pw->pw_shell,
                    pw->pw_shell);
        else
                shell = pw->pw_shell;

        login_close(lc);

        if (strcmp(shell, PATH_AUTHPF_SHELL)) {
                syslog(LOG_ERR, "wrong shell for user %s, uid %u",
                    pw->pw_name, pw->pw_uid);
                if (shell != pw->pw_shell)
                        free(shell);
                goto die;
        }

        if (shell != pw->pw_shell)
                free(shell);

        /*
         * Paranoia, but this data _does_ come from outside authpf, and
         * truncation would be bad.
         */
        if (strlcpy(luser, pw->pw_name, sizeof(luser)) >= sizeof(luser)) {
                syslog(LOG_ERR, "username too long: %s", pw->pw_name);
                goto die;
        }

        if ((n = snprintf(rulesetname, sizeof(rulesetname), "%s(%ld)",
            luser, (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
                syslog(LOG_INFO, "%s(%ld) too large, ruleset name will be %ld",
                    luser, (long)getpid(), (long)getpid());
                if ((n = snprintf(rulesetname, sizeof(rulesetname), "%ld",
                    (long)getpid())) < 0 || (u_int)n >= sizeof(rulesetname)) {
                        syslog(LOG_ERR, "pid too large for ruleset name");
                        goto die;
                }
        }


        /* Make our entry in /var/authpf as /var/authpf/ipaddr */
        n = snprintf(pidfile, sizeof(pidfile), "%s/%s", PATH_PIDFILE, ipsrc);
        if (n < 0 || (u_int)n >= sizeof(pidfile)) {
                syslog(LOG_ERR, "path to pidfile too long");
                goto die;
        }

        /*
         * If someone else is already using this ip, then this person
         * wants to switch users - so kill the old process and exit
         * as well.
         *
         * Note, we could print a message and tell them to log out, but the
         * usual case of this is that someone has left themselves logged in,
         * with the authenticated connection iconized and someone else walks
         * up to use and automatically logs in before using. If this just
         * gets rid of the old one silently, the new user never knows they
         * could have used someone else's old authentication. If we
         * tell them to log out before switching users it is an invitation
         * for abuse.
         */

        do {
                int     save_errno, otherpid = -1;
                char    otherluser[MAXLOGNAME];

                if ((pidfd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1 ||
                    (pidfp = fdopen(pidfd, "r+")) == NULL) {
                        if (pidfd != -1)
                                close(pidfd);
                        syslog(LOG_ERR, "cannot open or create %s: %s", pidfile,
                            strerror(errno));
                        goto die;
                }

                if (flock(fileno(pidfp), LOCK_EX|LOCK_NB) == 0)
                        break;
                save_errno = errno;

                /* Mark our pid, and username to our file. */

                rewind(pidfp);
                /* 31 == MAXLOGNAME - 1 */
                if (fscanf(pidfp, "%d\n%31s\n", &otherpid, otherluser) != 2)
                        otherpid = -1;
                syslog(LOG_DEBUG, "tried to lock %s, in use by pid %d: %s",
                    pidfile, otherpid, strerror(save_errno));

                if (otherpid > 0) {
                        syslog(LOG_INFO,
                            "killing prior auth (pid %d) of %s by user %s",
                            otherpid, ipsrc, otherluser);
                        if (kill((pid_t) otherpid, SIGTERM) == -1) {
                                syslog(LOG_INFO,
                                    "could not kill process %d: (%m)",
                                    otherpid);
                        }
                }

                /*
                 * we try to kill the previous process and acquire the lock
                 * for 10 seconds, trying once a second. if we can't after
                 * 10 attempts we log an error and give up
                 */
                if (++lockcnt > 10) {
                        syslog(LOG_ERR, "cannot kill previous authpf (pid %d)",
                            otherpid);
                        fclose(pidfp);
                        pidfp = NULL;
                        goto dogdeath;
                }
                sleep(1);

                /* re-open, and try again. The previous authpf process
                 * we killed above should unlink the file and release
                 * it's lock, giving us a chance to get it now
                 */
                fclose(pidfp);
                pidfp = NULL;
        } while (1);
        
        /* whack the group list */
        gid = getegid();
        if (setgroups(1, &gid) == -1) {
                syslog(LOG_INFO, "setgroups: %s", strerror(errno));
                do_death(0);
        }

        /* revoke privs */
        uid = getuid();
#if defined(__OpenBSD__)
        if (setresuid(uid, uid, uid) == -1) {
                syslog(LOG_INFO, "setresuid: %s", strerror(errno));
                do_death(0);
        }
#else /* defined(__OpenBSD__) */
        /* NetBSD */
        if (setuid(uid) == -1) {
                syslog(LOG_INFO, "setresuid: %s", strerror(errno));
                do_death(0);
        }
#endif /* defined(__OpenBSD__) */
        openlog("authpf", LOG_PID | LOG_NDELAY, LOG_DAEMON);

        if (!check_luser(PATH_BAN_DIR, luser) || !allowed_luser(luser)) {
                syslog(LOG_INFO, "user %s prohibited", luser);
                do_death(0);
        }

        if (read_config(config)) {
                syslog(LOG_ERR, "invalid config file %s", PATH_CONFFILE);
                do_death(0);
        }

        if (remove_stale_rulesets()) {
                syslog(LOG_INFO, "error removing stale rulesets");
                do_death(0);
        }

        /* We appear to be making headway, so actually mark our pid */
        rewind(pidfp);
        fprintf(pidfp, "%ld\n%s\n", (long)getpid(), luser);
        fflush(pidfp);
        (void) ftruncate(fileno(pidfp), ftello(pidfp));

        if (change_filter(1, luser, ipsrc) == -1) {
                printf("Unable to modify filters\r\n");
                do_death(0);
        }
        if (change_table(1, ipsrc) == -1) {
                printf("Unable to modify table\r\n");
                change_filter(0, luser, ipsrc);
                do_death(0);
        }

        signal(SIGTERM, need_death);
        signal(SIGINT, need_death);
        signal(SIGALRM, need_death);
        signal(SIGPIPE, need_death);
        signal(SIGHUP, need_death);
        signal(SIGQUIT, need_death);
        signal(SIGTSTP, need_death);
        while (1) {
                printf("\r\nHello %s. ", luser);
                printf("You are authenticated from host \"%s\"\r\n", ipsrc);
                setproctitle("%s@%s", luser, ipsrc);
                print_message(PATH_MESSAGE);
                while (1) {
                        sleep(10);
                        if (want_death)
                                do_death(1);
                }
        }

        /* NOTREACHED */
dogdeath:
        printf("\r\n\r\nSorry, this service is currently unavailable due to ");
        printf("technical difficulties\r\n\r\n");
        print_message(PATH_PROBLEM);
        printf("\r\nYour authentication process (pid %ld) was unable to run\n",
            (long)getpid());
        sleep(180); /* them lusers read reaaaaal slow */
die:
        do_death(0);
        return (0);
}

/*
 * reads config file in PATH_CONFFILE to set optional behaviours up
 */
static int
read_config(FILE *f)
{
        char    buf[1024];
        int     i = 0;

        do {
                char    **ap;
                char     *pair[4], *cp, *tp;
                int       len;

                if (fgets(buf, sizeof(buf), f) == NULL) {
                        fclose(f);
                        return (0);
                }
                i++;
                len = strlen(buf);
                if (buf[len - 1] != '\n' && !feof(f)) {
                        syslog(LOG_ERR, "line %d too long in %s", i,
                            PATH_CONFFILE);
                        return (1);
                }
                buf[len - 1] = '\0';

                for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
                        ; /* nothing */

                if (!*cp || *cp == '#' || *cp == '\n')
                        continue;

                for (ap = pair; ap < &pair[3] &&
                    (*ap = strsep(&cp, "=")) != NULL; ) {
                        if (**ap != '\0')
                                ap++;
                }
                if (ap != &pair[2])
                        goto parse_error;

                tp = pair[1] + strlen(pair[1]);
                while ((*tp == ' ' || *tp == '\t') && tp >= pair[1])
                        *tp-- = '\0';

                if (strcasecmp(pair[0], "anchor") == 0) {
                        if (!pair[1][0] || strlcpy(anchorname, pair[1],
                            sizeof(anchorname)) >= sizeof(anchorname))
                                goto parse_error;
                }
                if (strcasecmp(pair[0], "table") == 0) {
                        if (!pair[1][0] || strlcpy(tablename, pair[1],
                            sizeof(tablename)) >= sizeof(tablename))
                                goto parse_error;
                }
        } while (!feof(f) && !ferror(f));
        fclose(f);
        return (0);

parse_error:
        fclose(f);
        syslog(LOG_ERR, "parse error, line %d of %s", i, PATH_CONFFILE);
        return (1);
}


/*
 * splatter a file to stdout - max line length of 1024,
 * used for spitting message files at users to tell them
 * they've been bad or we're unavailable.
 */
static void
print_message(char *filename)
{
        char     buf[1024];
        FILE    *f;

        if ((f = fopen(filename, "r")) == NULL)
                return; /* fail silently, we don't care if it isn't there */

        do {
                if (fgets(buf, sizeof(buf), f) == NULL) {
                        fflush(stdout);
                        fclose(f);
                        return;
                }
        } while (fputs(buf, stdout) != EOF && !feof(f));
        fflush(stdout);
        fclose(f);
}

/*
 * allowed_luser checks to see if user "luser" is allowed to
 * use this gateway by virtue of being listed in an allowed
 * users file, namely /etc/authpf/authpf.allow .
 *
 * If /etc/authpf/authpf.allow does not exist, then we assume that
 * all users who are allowed in by sshd(8) are permitted to
 * use this gateway. If /etc/authpf/authpf.allow does exist, then a
 * user must be listed if the connection is to continue, else
 * the session terminates in the same manner as being banned.
 */
static int
allowed_luser(char *luser)
{
        char    *buf, *lbuf;
        int      matched;
        size_t   len;
        FILE    *f;

        if ((f = fopen(PATH_ALLOWFILE, "r")) == NULL) {
                if (errno == ENOENT) {
                        /*
                         * allowfile doesn't exist, thus this gateway
                         * isn't restricted to certain users...
                         */
                        return (1);
                }

                /*
                 * luser may in fact be allowed, but we can't open
                 * the file even though it's there. probably a config
                 * problem.
                 */
                syslog(LOG_ERR, "cannot open allowed users file %s (%s)",
                    PATH_ALLOWFILE, strerror(errno));
                return (0);
        } else {
                /*
                 * /etc/authpf/authpf.allow exists, thus we do a linear
                 * search to see if they are allowed.
                 * also, if username "*" exists, then this is a
                 * "public" gateway, such as it is, so let
                 * everyone use it.
                 */
                lbuf = NULL;
                while ((buf = fgetln(f, &len))) {
                        if (buf[len - 1] == '\n')
                                buf[len - 1] = '\0';
                        else {
                                if ((lbuf = (char *)malloc(len + 1)) == NULL)
                                        err(1, NULL);
                                memcpy(lbuf, buf, len);
                                lbuf[len] = '\0';
                                buf = lbuf;
                        }

                        matched = strcmp(luser, buf) == 0 || strcmp("*", buf) == 0;

                        if (lbuf != NULL) {
                                free(lbuf);
                                lbuf = NULL;
                        }

                        if (matched)
                                return (1); /* matched an allowed username */
                }
                syslog(LOG_INFO, "denied access to %s: not listed in %s",
                    luser, PATH_ALLOWFILE);

                /* reuse buf */
                buf = "\n\nSorry, you are not allowed to use this facility!\n";
                fputs(buf, stdout);
        }
        fflush(stdout);
        return (0);
}

/*
 * check_luser checks to see if user "luser" has been banned
 * from using us by virtue of having an file of the same name
 * in the "luserdir" directory.
 *
 * If the user has been banned, we copy the contents of the file
 * to the user's screen. (useful for telling the user what to
 * do to get un-banned, or just to tell them they aren't
 * going to be un-banned.)
 */
static int
check_luser(char *luserdir, char *luser)
{
        FILE    *f;
        int      n;
        char     tmp[MAXPATHLEN];

        n = snprintf(tmp, sizeof(tmp), "%s/%s", luserdir, luser);
        if (n < 0 || (u_int)n >= sizeof(tmp)) {
                syslog(LOG_ERR, "provided banned directory line too long (%s)",
                    luserdir);
                return (0);
        }
        if ((f = fopen(tmp, "r")) == NULL) {
                if (errno == ENOENT) {
                        /*
                         * file or dir doesn't exist, so therefore
                         * this luser isn't banned..  all is well
                         */
                        return (1);
                } else {
                        /*
                         * luser may in fact be banned, but we can't open the
                         * file even though it's there. probably a config
                         * problem.
                         */
                        syslog(LOG_ERR, "cannot open banned file %s (%s)",
                            tmp, strerror(errno));
                        return (0);
                }
        } else {
                /*
                 * luser is banned - spit the file at them to
                 * tell what they can do and where they can go.
                 */
                syslog(LOG_INFO, "denied access to %s: %s exists",
                    luser, tmp);

                /* reuse tmp */
                strlcpy(tmp, "\n\n-**- Sorry, you have been banned! -**-\n\n",
                    sizeof(tmp));
                while (fputs(tmp, stdout) != EOF && !feof(f)) {
                        if (fgets(tmp, sizeof(tmp), f) == NULL) {
                                fflush(stdout);
                                fclose(f);
                                return (0);
                        }
                }
                fclose(f);
        }
        fflush(stdout);
        return (0);
}

/*
 * Search for rulesets left by other authpf processes (either because they
 * died ungracefully or were terminated) and remove them.
 */
static int
remove_stale_rulesets(void)
{
        struct pfioc_ruleset     prs;
        u_int32_t                nr, mnr;

        memset(&prs, 0, sizeof(prs));
        strlcpy(prs.path, anchorname, sizeof(prs.path));
        if (ioctl(dev, DIOCGETRULESETS, &prs)) {
                if (errno == EINVAL)
                        return (0);
                else
                        return (1);
        }

        mnr = prs.nr;
        nr = 0;
        while (nr < mnr) {
                char    *s, *t;
                pid_t    pid;

                prs.nr = nr;
                if (ioctl(dev, DIOCGETRULESET, &prs))
                        return (1);
                errno = 0;
                if ((t = strchr(prs.name, '(')) == NULL)
                        t = prs.name;
                else
                        t++;
                pid = strtoul(t, &s, 10);
                if (!prs.name[0] || errno ||
                    (*s && (t == prs.name || *s != ')')))
                        return (1);
                if (kill(pid, 0) && errno != EPERM) {
                        int                     i;
                        struct pfioc_trans_e    t_e[PF_RULESET_MAX+1];
                        struct pfioc_trans      t;

                        bzero(&t, sizeof(t));
                        bzero(t_e, sizeof(t_e));
                        t.size = PF_RULESET_MAX+1;
                        t.esize = sizeof(t_e[0]);
                        t.array = t_e;
                        for (i = 0; i < PF_RULESET_MAX+1; ++i) {
                                t_e[i].rs_num = i;
                                snprintf(t_e[i].anchor, sizeof(t_e[i].anchor),
                                    "%s/%s", anchorname, prs.name);
                        }
                        t_e[PF_RULESET_MAX].rs_num = PF_RULESET_TABLE;
                        if ((ioctl(dev, DIOCXBEGIN, &t) ||
                            ioctl(dev, DIOCXCOMMIT, &t)) &&
                            errno != EINVAL)
                                return (1);
                        mnr--;
                } else
                        nr++;
        }
        return (0);
}

/*
 * Add/remove filter entries for user "luser" from ip "ipsrc"
 */
static int
change_filter(int add, const char *luser, const char *ipsrc)
{
        char    *pargv[13] = {
                "pfctl", "-p", "/dev/pf", "-q", "-a", "anchor/ruleset",
                "-D", "user_ip=X", "-D", "user_id=X", "-f",
                "file", NULL
        };
        char    *fdpath = NULL, *userstr = NULL, *ipstr = NULL;
        char    *rsn = NULL, *fn = NULL;
        pid_t   pid;
        gid_t   gid;
        int     s;

        if (luser == NULL || !luser[0] || ipsrc == NULL || !ipsrc[0]) {
                syslog(LOG_ERR, "invalid luser/ipsrc");
                goto error;
        }

        if (asprintf(&rsn, "%s/%s", anchorname, rulesetname) == -1)
                goto no_mem;
        if (asprintf(&fdpath, "/dev/fd/%d", dev) == -1)
                goto no_mem;
        if (asprintf(&ipstr, "user_ip=%s", ipsrc) == -1)
                goto no_mem;
        if (asprintf(&userstr, "user_id=%s", luser) == -1)
                goto no_mem;

        if (add) {
                struct stat sb;

                if (asprintf(&fn, "%s/%s/authpf.rules", PATH_USER_DIR, luser)
                    == -1)
                        goto no_mem;
                if (stat(fn, &sb) == -1) {
                        free(fn);
                        if ((fn = strdup(PATH_PFRULES)) == NULL)
                                goto no_mem;
                }
        }
        pargv[2] = fdpath;
        pargv[5] = rsn;
        pargv[7] = userstr;
        pargv[9] = ipstr;
        if (!add)
                pargv[11] = "/dev/null";
        else
                pargv[11] = fn;

        switch (pid = fork()) {
        case -1:
                syslog(LOG_ERR, "fork failed");
                goto error;
        case 0:
                /* revoke group privs before exec */
                gid = getgid();
                if (setregid(gid, gid) == -1) {
                        err(1, "setregid");
                }
                execvp(PATH_PFCTL, pargv);
                warn("exec of %s failed", PATH_PFCTL);
                _exit(1);
        }

        /* parent */
        waitpid(pid, &s, 0);
        if (s != 0) {
                syslog(LOG_ERR, "pfctl exited abnormally");
                goto error;
        }

        if (add) {
                gettimeofday(&Tstart, NULL);
                syslog(LOG_INFO, "allowing %s, user %s", ipsrc, luser);
        } else {
                gettimeofday(&Tend, NULL);
                syslog(LOG_INFO, "removed %s, user %s - duration %lld seconds",
                    ipsrc, luser, (long long)(Tend.tv_sec - Tstart.tv_sec));
        }
        return (0);
no_mem:
        syslog(LOG_ERR, "malloc failed");
error:
        free(fdpath);
        free(rsn);
        free(userstr);
        free(ipstr);
        free(fn);
        return (-1);
}

/*
 * Add/remove this IP from the "authpf_users" table.
 */
static int
change_table(int add, const char *ipsrc)
{
        struct pfioc_table      io;
        struct pfr_addr         addr;

        bzero(&io, sizeof(io));
        strlcpy(io.pfrio_table.pfrt_name, tablename,
            sizeof(io.pfrio_table.pfrt_name));
        io.pfrio_buffer = &addr;
        io.pfrio_esize = sizeof(addr);
        io.pfrio_size = 1;

        bzero(&addr, sizeof(addr));
        if (ipsrc == NULL || !ipsrc[0])
                return (-1);
        if (inet_pton(AF_INET, ipsrc, &addr.pfra_ip4addr) == 1) {
                addr.pfra_af = AF_INET;
                addr.pfra_net = 32;
        } else if (inet_pton(AF_INET6, ipsrc, &addr.pfra_ip6addr) == 1) {
                addr.pfra_af = AF_INET6;
                addr.pfra_net = 128;
        } else {
                syslog(LOG_ERR, "invalid ipsrc");
                return (-1);
        }

        if (ioctl(dev, add ? DIOCRADDADDRS : DIOCRDELADDRS, &io) &&
            errno != ESRCH) {
                syslog(LOG_ERR, "cannot %s %s from table %s: %s",
                    add ? "add" : "remove", ipsrc, tablename,
                    strerror(errno));
                return (-1);
        }
        return (0);
}

/*
 * This is to kill off states that would otherwise be left behind stateful
 * rules. This means we don't need to allow in more traffic than we really
 * want to, since we don't have to worry about any luser sessions lasting
 * longer than their ssh session. This function is based on
 * pfctl_kill_states from pfctl.
 */
static void
authpf_kill_states(void)
{
        struct pfioc_state_kill psk;
        struct pf_addr target;

        memset(&psk, 0, sizeof(psk));
        memset(&target, 0, sizeof(target));

        if (inet_pton(AF_INET, ipsrc, &target.v4) == 1)
                psk.psk_af = AF_INET;
        else if (inet_pton(AF_INET6, ipsrc, &target.v6) == 1)
                psk.psk_af = AF_INET6;
        else {
                syslog(LOG_ERR, "inet_pton(%s) failed", ipsrc);
                return;
        }

        /* Kill all states from ipsrc */
        memcpy(&psk.psk_src.addr.v.a.addr, &target,
            sizeof(psk.psk_src.addr.v.a.addr));
        memset(&psk.psk_src.addr.v.a.mask, 0xff,
            sizeof(psk.psk_src.addr.v.a.mask));
        if (ioctl(dev, DIOCKILLSTATES, &psk))
                syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");

        /* Kill all states to ipsrc */
        memset(&psk.psk_src, 0, sizeof(psk.psk_src));
        memcpy(&psk.psk_dst.addr.v.a.addr, &target,
            sizeof(psk.psk_dst.addr.v.a.addr));
        memset(&psk.psk_dst.addr.v.a.mask, 0xff,
            sizeof(psk.psk_dst.addr.v.a.mask));
        if (ioctl(dev, DIOCKILLSTATES, &psk))
                syslog(LOG_ERR, "DIOCKILLSTATES failed (%m)");
}

/* signal handler that makes us go away properly */
static void
need_death(int signo)
{
        want_death = 1;
}

/*
 * function that removes our stuff when we go away.
 */
static __dead void
do_death(int active)
{
        int     ret = 0;

        if (active) {
                change_filter(0, luser, ipsrc);
                change_table(0, ipsrc);
                authpf_kill_states();
                remove_stale_rulesets();
        }
        if (pidfile[0] && (pidfp != NULL))
                if (unlink(pidfile) == -1)
                        syslog(LOG_ERR, "cannot unlink %s (%m)", pidfile);
        exit(ret);
}