/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 James Gritton
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/cpuset.h>
#include <sys/event.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <sys/wait.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <kvm.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vis.h>

#include "jailp.h"

#define DEFAULT_STOP_TIMEOUT    10
#define PHASH_SIZE              256

LIST_HEAD(phhead, phash);

struct phash {
        LIST_ENTRY(phash)       le;
        struct cfjail           *j;
        pid_t                   pid;
};

int paralimit = -1;

extern char **environ;

static int run_command(struct cfjail *j);
static int add_proc(struct cfjail *j, pid_t pid);
static void clear_procs(struct cfjail *j);
static struct cfjail *find_proc(pid_t pid);
static int term_procs(struct cfjail *j);
static int get_user_info(struct cfjail *j, const char *username,
    const struct passwd **pwdp, login_cap_t **lcapp);
static int check_path(struct cfjail *j, const char *pname, const char *path,
    int isfile, const char *umount_type);

static struct cfjails sleeping = TAILQ_HEAD_INITIALIZER(sleeping);
static struct cfjails runnable = TAILQ_HEAD_INITIALIZER(runnable);
static struct cfstring dummystring = { .len = 1 };
static struct phhead phash[PHASH_SIZE];
static int kq;

static cpusetid_t
root_cpuset_id(void)
{
        static cpusetid_t setid = CPUSET_INVALID;
        static int error;

        /* Only try to get the cpuset once. */
        if (error == 0 && setid == CPUSET_INVALID)
                error = cpuset_getid(CPU_LEVEL_ROOT, CPU_WHICH_PID, -1, &setid);
        if (error != 0)
                return (CPUSET_INVALID);
        return (setid);
}

/*
 * Run the next command associated with a jail.
 */
int
next_command(struct cfjail *j)
{
        enum intparam comparam;
        int create_failed, stopping;

        if (paralimit == 0) {
                if (j->flags & JF_FROM_RUNQ)
                        requeue_head(j, &runnable);
                else
                        requeue(j, &runnable);
                return 1;
        }
        j->flags &= ~JF_FROM_RUNQ;
        create_failed = (j->flags & (JF_STOP | JF_FAILED)) == JF_FAILED;
        stopping = (j->flags & JF_STOP) != 0;
        comparam = *j->comparam;
        for (;;) {
                if (j->comstring == NULL) {
                        j->comparam += create_failed ? -1 : 1;
                        switch ((comparam = *j->comparam)) {
                        case IP__NULL:
                                return 0;
                        case IP_MOUNT_DEVFS:
                                if (!bool_param(j->intparams[IP_MOUNT_DEVFS]))
                                        continue;
                                j->comstring = &dummystring;
                                break;
                        case IP_MOUNT_FDESCFS:
                                if (!bool_param(j->intparams[IP_MOUNT_FDESCFS]))
                                        continue;
                                j->comstring = &dummystring;
                                break;
                        case IP_MOUNT_PROCFS:
                                if (!bool_param(j->intparams[IP_MOUNT_PROCFS]))
                                        continue;
                                j->comstring = &dummystring;
                                break;
                        case IP__OP:
                        case IP_STOP_TIMEOUT:
                                j->comstring = &dummystring;
                                break;
                        default:
                                if (j->intparams[comparam] == NULL)
                                        continue;
                                j->comstring = create_failed || (stopping &&
                                    (j->intparams[comparam]->flags & PF_REV))
                                    ? TAILQ_LAST(&j->intparams[comparam]->val,
                                        cfstrings)
                                    : TAILQ_FIRST(&j->intparams[comparam]->val);
                        }
                } else {
                        j->comstring = j->comstring == &dummystring ? NULL :
                            create_failed || (stopping &&
                            (j->intparams[comparam]->flags & PF_REV))
                            ? TAILQ_PREV(j->comstring, cfstrings, tq)
                            : TAILQ_NEXT(j->comstring, tq);
                }
                if (j->comstring == NULL || j->comstring->len == 0 ||
                    (create_failed && (comparam == IP_EXEC_PRESTART ||
                    comparam == IP_EXEC_CREATED || comparam == IP_EXEC_START ||
                    comparam == IP_COMMAND || comparam == IP_EXEC_POSTSTART ||
                    comparam == IP_EXEC_PREPARE)))
                        continue;
                switch (run_command(j)) {
                case -1:
                        failed(j);
                        /* FALLTHROUGH */
                case 1:
                        return 1;
                }
        }
}

/*
 * Check command exit status
 */
int
finish_command(struct cfjail *j)
{
        struct cfjail *rj;
        int error;

        if (!(j->flags & JF_SLEEPQ))
                return 0;
        j->flags &= ~JF_SLEEPQ;
        if (*j->comparam == IP_STOP_TIMEOUT) {
                j->flags &= ~JF_TIMEOUT;
                j->pstatus = 0;
                return 0;
        }
        paralimit++;
        if (!TAILQ_EMPTY(&runnable)) {
                rj = TAILQ_FIRST(&runnable);
                rj->flags |= JF_FROM_RUNQ;
                requeue(rj, &ready);
        }
        error = 0;
        if (j->flags & JF_TIMEOUT) {
                j->flags &= ~JF_TIMEOUT;
                if (*j->comparam != IP_STOP_TIMEOUT) {
                        jail_warnx(j, "%s: timed out", j->comline);
                        failed(j);
                        error = -1;
                } else if (verbose > 0)
                        jail_note(j, "timed out\n");
        } else if (j->pstatus != 0) {
                if (WIFSIGNALED(j->pstatus))
                        jail_warnx(j, "%s: exited on signal %d",
                            j->comline, WTERMSIG(j->pstatus));
                else
                        jail_warnx(j, "%s: failed", j->comline);
                j->pstatus = 0;
                failed(j);
                error = -1;
        }
        free(j->comline);
        j->comline = NULL;
        return error;
}

/*
 * Check for finished processes or timeouts.
 */
struct cfjail *
next_proc(int nonblock)
{
        struct kevent ke;
        struct timespec ts;
        struct timespec *tsp;
        struct cfjail *j;

        if (!TAILQ_EMPTY(&sleeping)) {
        again:
                tsp = NULL;
                if ((j = TAILQ_FIRST(&sleeping)) && j->timeout.tv_sec) {
                        clock_gettime(CLOCK_REALTIME, &ts);
                        ts.tv_sec = j->timeout.tv_sec - ts.tv_sec;
                        ts.tv_nsec = j->timeout.tv_nsec - ts.tv_nsec;
                        if (ts.tv_nsec < 0) {
                                ts.tv_sec--;
                                ts.tv_nsec += 1000000000;
                        }
                        if (ts.tv_sec < 0 ||
                            (ts.tv_sec == 0 && ts.tv_nsec == 0)) {
                                j->flags |= JF_TIMEOUT;
                                clear_procs(j);
                                return j;
                        }
                        tsp = &ts;
                }
                if (nonblock) {
                        ts.tv_sec = 0;
                        ts.tv_nsec = 0;
                        tsp = &ts;
                }
                switch (kevent(kq, NULL, 0, &ke, 1, tsp)) {
                case -1:
                        if (errno != EINTR)
                                err(1, "kevent");
                        goto again;
                case 0:
                        if (!nonblock) {
                                j = TAILQ_FIRST(&sleeping);
                                j->flags |= JF_TIMEOUT;
                                clear_procs(j);
                                return j;
                        }
                        break;
                case 1:
                        (void)waitpid(ke.ident, NULL, WNOHANG);
                        if ((j = find_proc(ke.ident))) {
                                j->pstatus = ke.data;
                                return j;
                        }
                        goto again;
                }
        }
        return NULL;
}

/*
 * Run a single command for a jail, possibly inside the jail.
 */
static int
run_command(struct cfjail *j)
{
        const struct passwd *pwd;
        const struct cfstring *comstring, *s;
        login_cap_t *lcap;
        const char **argv;
        char *acs, *cs, *comcs, *devpath;
        const char *jidstr, *conslog, *fmt, *path, *ruleset, *term, *username;
        enum intparam comparam;
        size_t comlen, ret;
        pid_t pid;
        cpusetid_t setid;
        int argc, bg, clean, consfd, down, fib, i, injail, sjuser, timeout;
#if defined(INET) || defined(INET6)
        char *addr, *extrap, *p, *val;
#endif

        static char *cleanenv;

        /* Perform some operations that aren't actually commands */
        comparam = *j->comparam;
        down = j->flags & (JF_STOP | JF_FAILED);
        switch (comparam) {
        case IP_STOP_TIMEOUT:
                return term_procs(j);

        case IP__OP:
                if (down) {
                        if (jail_remove(j->jid) < 0 && errno == EPERM) {
                                jail_warnx(j, "jail_remove: %s",
                                           strerror(errno));
                                return -1;
                        }
                        if (verbose > 0 || (verbose == 0 && (j->flags & JF_STOP
                            ? note_remove : j->name != NULL)))
                            jail_note(j, "removed\n");
                        j->jid = -1;
                        if (j->flags & JF_STOP)
                                dep_done(j, DF_LIGHT);
                        else
                                j->flags &= ~JF_PERSIST;
                } else {
                        if (create_jail(j) < 0)
                                return -1;
                        if (iflag)
                                printf("%d\n", j->jid);
                        if (verbose >= 0 && (j->name || verbose > 0))
                                jail_note(j, "created\n");

                        /*
                         * Populate our jid and name parameters if they were not
                         * provided.  This simplifies later logic that wants to
                         * use the jid or name to be able to do so reliably.
                         */
                        if (j->intparams[KP_JID] == NULL) {
                                char ljidstr[16];

                                (void)snprintf(ljidstr, sizeof(ljidstr), "%d",
                                    j->jid);
                                add_param(j, NULL, KP_JID, ljidstr);
                        }

                        /* This matches the kernel behavior. */
                        if (j->intparams[KP_NAME] == NULL)
                                add_param(j, j->intparams[KP_JID], KP_NAME,
                                    NULL);

                        dep_done(j, DF_LIGHT);
                }
                return 0;

        default: ;
        }
        /*
         * Collect exec arguments.  Internal commands for network and
         * mounting build their own argument lists.
         */
        comstring = j->comstring;
        bg = 0;
        switch (comparam) {
#ifdef INET
        case IP__IP4_IFADDR:
                argc = 0;
                val = alloca(strlen(comstring->s) + 1);
                strcpy(val, comstring->s);
                cs = val;
                extrap = NULL;
                while ((p = strchr(cs, ' ')) != NULL && strlen(p) > 1) {
                        if (extrap == NULL) {
                                *p = '\0';
                                extrap = p + 1;
                        }
                        cs = p + 1;
                        argc++;
                }

                argv = alloca((8 + argc) * sizeof(char *));
                argv[0] = _PATH_IFCONFIG;
                if ((cs = strchr(val, '|'))) {
                        argv[1] = acs = alloca(cs - val + 1);
                        strlcpy(acs, val, cs - val + 1);
                        addr = cs + 1;
                } else {
                        argv[1] = string_param(j->intparams[IP_INTERFACE]);
                        addr = val;
                }
                argv[2] = "inet";
                if (!(cs = strchr(addr, '/'))) {
                        argv[3] = addr;
                        argv[4] = "netmask";
                        argv[5] = "255.255.255.255";
                        argc = 6;
                } else if (strchr(cs + 1, '.')) {
                        argv[3] = acs = alloca(cs - addr + 1);
                        strlcpy(acs, addr, cs - addr + 1);
                        argv[4] = "netmask";
                        argv[5] = cs + 1;
                        argc = 6;
                } else {
                        argv[3] = addr;
                        argc = 4;
                }

                if (!down && extrap != NULL) {
                        for (cs = strtok(extrap, " "); cs;
                             cs = strtok(NULL, " ")) {
                                size_t len = strlen(cs) + 1;
                                argv[argc++] = acs = alloca(len);
                                strlcpy(acs, cs, len);
                        }
                }

                argv[argc] = down ? "-alias" : "alias";
                argv[argc + 1] = NULL;
                break;
#endif

#ifdef INET6
        case IP__IP6_IFADDR:
                argc = 0;
                val = alloca(strlen(comstring->s) + 1);
                strcpy(val, comstring->s);
                cs = val;
                extrap = NULL;
                while ((p = strchr(cs, ' ')) != NULL && strlen(p) > 1) {
                        if (extrap == NULL) {
                                *p = '\0';
                                extrap = p + 1;
                        }
                        cs = p + 1;
                        argc++;
                }

                argv = alloca((8 + argc) * sizeof(char *));
                argv[0] = _PATH_IFCONFIG;
                if ((cs = strchr(val, '|'))) {
                        argv[1] = acs = alloca(cs - val + 1);
                        strlcpy(acs, val, cs - val + 1);
                        addr = cs + 1;
                } else {
                        argv[1] = string_param(j->intparams[IP_INTERFACE]);
                        addr = val;
                }
                argv[2] = "inet6";
                argv[3] = addr;
                if (!(cs = strchr(addr, '/'))) {
                        argv[4] = "prefixlen";
                        argv[5] = "128";
                        argc = 6;
                } else
                        argc = 4;

                if (!down && extrap != NULL) {
                        for (cs = strtok(extrap, " "); cs;
                             cs = strtok(NULL, " ")) {
                                size_t len = strlen(cs) + 1;
                                argv[argc++] = acs = alloca(len);
                                strlcpy(acs, cs, len);
                        }
                }

                argv[argc] = down ? "-alias" : "alias";
                argv[argc + 1] = NULL;
                break;
#endif

        case IP_VNET_INTERFACE:
                argv = alloca(5 * sizeof(char *));
                argv[0] = _PATH_IFCONFIG;
                argv[1] = comstring->s;
                argv[2] = down ? "-vnet" : "vnet";
                argv[3] = string_param(j->intparams[KP_JID]);
                argv[4] = NULL;
                break;

        case IP_MOUNT:
        case IP__MOUNT_FROM_FSTAB:
                argv = alloca(8 * sizeof(char *));
                comcs = alloca(comstring->len + 1);
                strcpy(comcs, comstring->s);
                argc = 0;
                for (cs = strtok(comcs, " \t\f\v\r\n"); cs && argc < 4;
                     cs = strtok(NULL, " \t\f\v\r\n")) {
                        if (argc <= 1 && strunvis(cs, cs) < 0) {
                                jail_warnx(j, "%s: %s: fstab parse error",
                                    j->intparams[comparam]->name, comstring->s);
                                return -1;
                        }
                        argv[argc++] = cs;
                }
                if (argc == 0)
                        return 0;
                if (argc < 3) {
                        jail_warnx(j, "%s: %s: missing information",
                            j->intparams[comparam]->name, comstring->s);
                        return -1;
                }
                if (check_path(j, j->intparams[comparam]->name, argv[1], 0,
                    down ? argv[2] : NULL) < 0)
                        return -1;
                if (down) {
                        argv[4] = NULL;
                        argv[3] = argv[1];
                        argv[0] = "/sbin/umount";
                } else {
                        if (argc == 4) {
                                argv[7] = NULL;
                                argv[6] = argv[1];
                                argv[5] = argv[0];
                                argv[4] = argv[3];
                                argv[3] = "-o";
                        } else {
                                argv[5] = NULL;
                                argv[4] = argv[1];
                                argv[3] = argv[0];
                        }
                        argv[0] = _PATH_MOUNT;
                }
                argv[1] = "-t";
                break;

        case IP_MOUNT_DEVFS:
                argv = alloca(7 * sizeof(char *));
                path = string_param(j->intparams[KP_PATH]);
                if (path == NULL) {
                        jail_warnx(j, "mount.devfs: no jail root path defined");
                        return -1;
                }
                devpath = alloca(strlen(path) + 5);
                sprintf(devpath, "%s/dev", path);
                if (check_path(j, "mount.devfs", devpath, 0,
                    down ? "devfs" : NULL) < 0)
                        return -1;
                if (down) {
                        argv[0] = "/sbin/umount";
                        argv[1] = devpath;
                        argv[2] = NULL;
                } else {
                        argv[0] = _PATH_MOUNT;
                        argv[1] = "-t";
                        argv[2] = "devfs";
                        ruleset = string_param(j->intparams[KP_DEVFS_RULESET]);
                        if (!ruleset)
                            ruleset = "4";      /* devfsrules_jail */
                        argv[3] = acs = alloca(11 + strlen(ruleset));
                        sprintf(acs, "-oruleset=%s", ruleset);
                        argv[4] = ".";
                        argv[5] = devpath;
                        argv[6] = NULL;
                }
                break;

        case IP_MOUNT_FDESCFS:
                argv = alloca(7 * sizeof(char *));
                path = string_param(j->intparams[KP_PATH]);
                if (path == NULL) {
                        jail_warnx(j, "mount.fdescfs: no jail root path defined");
                        return -1;
                }
                devpath = alloca(strlen(path) + 8);
                sprintf(devpath, "%s/dev/fd", path);
                if (check_path(j, "mount.fdescfs", devpath, 0,
                    down ? "fdescfs" : NULL) < 0)
                        return -1;
                if (down) {
                        argv[0] = "/sbin/umount";
                        argv[1] = devpath;
                        argv[2] = NULL;
                } else {
                        argv[0] = _PATH_MOUNT;
                        argv[1] = "-t";
                        argv[2] = "fdescfs";
                        argv[3] = ".";
                        argv[4] = devpath;
                        argv[5] = NULL;
                }
                break;

        case IP_MOUNT_PROCFS:
                argv = alloca(7 * sizeof(char *));
                path = string_param(j->intparams[KP_PATH]);
                if (path == NULL) {
                        jail_warnx(j, "mount.procfs: no jail root path defined");
                        return -1;
                }
                devpath = alloca(strlen(path) + 6);
                sprintf(devpath, "%s/proc", path);
                if (check_path(j, "mount.procfs", devpath, 0,
                    down ? "procfs" : NULL) < 0)
                        return -1;
                if (down) {
                        argv[0] = "/sbin/umount";
                        argv[1] = devpath;
                        argv[2] = NULL;
                } else {
                        argv[0] = _PATH_MOUNT;
                        argv[1] = "-t";
                        argv[2] = "procfs";
                        argv[3] = ".";
                        argv[4] = devpath;
                        argv[5] = NULL;
                }
                break;

        case IP_ZFS_DATASET:
                argv = alloca(4 * sizeof(char *));
                jidstr = string_param(j->intparams[KP_JID]);
                fmt = "if [ $(/sbin/zfs get -H -o value jailed %s) = on ]; then /sbin/zfs jail %s %s || echo error, attaching %s to jail %s failed; else echo error, you need to set jailed=on for dataset %s; fi";
                comlen = strlen(fmt)
                    + 2 * strlen(jidstr)
                    + 4 * comstring->len
                    - 6 * 2     /* 6 * "%s" */
                    + 1;
                comcs = alloca(comlen);
                ret = snprintf(comcs, comlen, fmt, comstring->s,
                    jidstr, comstring->s, comstring->s, jidstr,
                    comstring->s);
                if (ret >= comlen) {
                        jail_warnx(j, "internal error in ZFS dataset handling");
                        exit(1);
                }
                argv[0] = _PATH_BSHELL;
                argv[1] = "-c";
                argv[2] = comcs;
                argv[3] = NULL;
                break;

        case IP_COMMAND:
                if (j->name != NULL)
                        goto default_command;
                argc = 0;
                TAILQ_FOREACH(s, &j->intparams[IP_COMMAND]->val, tq)
                        argc++;
                argv = alloca((argc + 1) * sizeof(char *));
                argc = 0;
                TAILQ_FOREACH(s, &j->intparams[IP_COMMAND]->val, tq)
                        argv[argc++] = s->s;
                argv[argc] = NULL;
                j->comstring = &dummystring;
                break;

        default:
        default_command:
                if ((cs = strpbrk(comstring->s, "!\"$&'()*;<>?[\\]`{|}~")) &&
                    !(cs[0] == '&' && cs[1] == '\0')) {
                        argv = alloca(4 * sizeof(char *));
                        argv[0] = _PATH_BSHELL;
                        argv[1] = "-c";
                        argv[2] = comstring->s;
                        argv[3] = NULL;
                } else {
                        if (cs) {
                                *cs = 0;
                                bg = 1;
                        }
                        comcs = alloca(comstring->len + 1);
                        strcpy(comcs, comstring->s);
                        argc = 0;
                        for (cs = strtok(comcs, " \t\f\v\r\n"); cs;
                             cs = strtok(NULL, " \t\f\v\r\n"))
                                argc++;
                        argv = alloca((argc + 1) * sizeof(char *));
                        strcpy(comcs, comstring->s);
                        argc = 0;
                        for (cs = strtok(comcs, " \t\f\v\r\n"); cs;
                             cs = strtok(NULL, " \t\f\v\r\n"))
                                argv[argc++] = cs;
                        argv[argc] = NULL;
                }
        }
        if (argv[0] == NULL)
                return 0;

        if (int_param(j->intparams[IP_EXEC_TIMEOUT], &timeout) &&
            timeout != 0) {
                clock_gettime(CLOCK_REALTIME, &j->timeout);
                j->timeout.tv_sec += timeout;
        } else
                j->timeout.tv_sec = 0;

        injail = comparam == IP_EXEC_START || comparam == IP_COMMAND ||
            comparam == IP_EXEC_STOP;
        if (injail)
                setid = root_cpuset_id();
        else
                setid = CPUSET_INVALID;
        clean = bool_param(j->intparams[IP_EXEC_CLEAN]);
        username = string_param(j->intparams[injail
            ? IP_EXEC_JAIL_USER : IP_EXEC_SYSTEM_USER]);
        sjuser = bool_param(j->intparams[IP_EXEC_SYSTEM_JAIL_USER]);

        consfd = 0;
        if (injail &&
            (conslog = string_param(j->intparams[IP_EXEC_CONSOLELOG]))) {
                if (check_path(j, "exec.consolelog", conslog, 1, NULL) < 0)
                        return -1;
                consfd =
                    open(conslog, O_WRONLY | O_CREAT | O_APPEND, DEFFILEMODE);
                if (consfd < 0) {
                        jail_warnx(j, "open %s: %s", conslog, strerror(errno));
                        return -1;
                }
        }

        comlen = 0;
        for (i = 0; argv[i]; i++)
                comlen += strlen(argv[i]) + 1;
        j->comline = cs = emalloc(comlen);
        for (i = 0; argv[i]; i++) {
                strcpy(cs, argv[i]);
                if (argv[i + 1]) {
                        cs += strlen(argv[i]) + 1;
                        cs[-1] = ' ';
                }
        }
        if (verbose > 0)
                jail_note(j, "run command%s%s%s: %s\n",
                    injail ? " in jail" : "", username ? " as " : "",
                    username ? username : "", j->comline);

        pid = fork();
        if (pid < 0)
                err(1, "fork");
        if (pid > 0) {
                if (bg || !add_proc(j, pid)) {
                        free(j->comline);
                        j->comline = NULL;
                        return 0;
                } else {
                        paralimit--;
                        return 1;
                }
        }
        if (bg)
                setsid();

        /* Set up the environment and run the command */
        pwd = NULL;
        lcap = NULL;
        if ((clean || username) && injail && sjuser &&
            get_user_info(j, username, &pwd, &lcap) < 0)
                exit(1);
        if (injail) {
                /* jail_attach won't chdir along with its chroot. */
                path = string_param(j->intparams[KP_PATH]);
                if (path && chdir(path) < 0) {
                        jail_warnx(j, "chdir %s: %s", path, strerror(errno));
                        exit(1);
                }
                if (int_param(j->intparams[IP_EXEC_FIB], &fib) &&
                    setfib(fib) < 0) {
                        jail_warnx(j, "setfib: %s", strerror(errno));
                        exit(1);
                }

                /*
                 * We wouldn't have specialized our affinity, so just setid to
                 * root.  We do this prior to attaching to avoid the kernel
                 * having to create a transient cpuset that we'll promptly
                 * free up with a reset to the jail's cpuset.
                 *
                 * This is just a best-effort to use as wide of mask as
                 * possible.
                 */
                if (setid != CPUSET_INVALID)
                        (void)cpuset_setid(CPU_WHICH_PID, -1, setid);

                if (jail_attach(j->jid) < 0) {
                        jail_warnx(j, "jail_attach: %s", strerror(errno));
                        exit(1);
                }
        }
        if (clean || username) {
                if (!(injail && sjuser) &&
                    get_user_info(j, username, &pwd, &lcap) < 0)
                        exit(1);
                if (clean) {
                        term = getenv("TERM");
                        environ = &cleanenv;
                        setenv("PATH", "/bin:/usr/bin", 0);
                        if (term != NULL)
                                setenv("TERM", term, 1);
                }
                if (setgid(pwd->pw_gid) < 0) {
                        jail_warnx(j, "setgid %d: %s", pwd->pw_gid,
                            strerror(errno));
                        exit(1);
                }
                if (setusercontext(lcap, pwd, pwd->pw_uid, username
                    ? LOGIN_SETALL & ~LOGIN_SETGROUP & ~LOGIN_SETLOGIN
                    : LOGIN_SETPATH | LOGIN_SETENV) < 0) {
                        jail_warnx(j, "setusercontext %s: %s", pwd->pw_name,
                            strerror(errno));
                        exit(1);
                }
                login_close(lcap);
                setenv("USER", pwd->pw_name, 1);
                setenv("HOME", pwd->pw_dir, 1);
                setenv("SHELL",
                    *pwd->pw_shell ? pwd->pw_shell : _PATH_BSHELL, 1);
                if (clean && username && chdir(pwd->pw_dir) < 0) {
                        jail_warnx(j, "chdir %s: %s",
                            pwd->pw_dir, strerror(errno));
                        exit(1);
                }
                endpwent();
        }
        if (!injail) {
                if (string_param(j->intparams[KP_JID]))
                        setenv("JID", string_param(j->intparams[KP_JID]), 1);
                if (string_param(j->intparams[KP_NAME]))
                        setenv("JNAME", string_param(j->intparams[KP_NAME]), 1);
                path = string_param(j->intparams[KP_PATH]);
                setenv("JPATH", path ? path : "", 1);
        }

        if (consfd != 0 && (dup2(consfd, 1) < 0 || dup2(consfd, 2) < 0)) {
                jail_warnx(j, "exec.consolelog: %s", strerror(errno));
                exit(1);
        }
        closefrom(3);
        execvp(argv[0], __DECONST(char *const*, argv));
        jail_warnx(j, "exec %s: %s", argv[0], strerror(errno));
        exit(1);
}

/*
 * Add a process to the hash, tied to a jail.
 */
static int
add_proc(struct cfjail *j, pid_t pid)
{
        struct kevent ke;
        struct cfjail *tj;
        struct phash *ph;

        if (!kq && (kq = kqueue()) < 0)
                err(1, "kqueue");
        EV_SET(&ke, pid, EVFILT_PROC, EV_ADD, NOTE_EXIT, 0, NULL);
        if (kevent(kq, &ke, 1, NULL, 0, NULL) < 0) {
                if (errno == ESRCH)
                        return 0;
                err(1, "kevent");
        }
        ph = emalloc(sizeof(struct phash));
        ph->j = j;
        ph->pid = pid;
        LIST_INSERT_HEAD(&phash[pid % PHASH_SIZE], ph, le);
        j->nprocs++;
        j->flags |= JF_SLEEPQ;
        if (j->timeout.tv_sec == 0)
                requeue(j, &sleeping);
        else {
                /* File the jail in the sleep queue according to its timeout. */
                TAILQ_REMOVE(j->queue, j, tq);
                TAILQ_FOREACH(tj, &sleeping, tq) {
                        if (!tj->timeout.tv_sec ||
                            j->timeout.tv_sec < tj->timeout.tv_sec ||
                            (j->timeout.tv_sec == tj->timeout.tv_sec &&
                            j->timeout.tv_nsec <= tj->timeout.tv_nsec)) {
                                TAILQ_INSERT_BEFORE(tj, j, tq);
                                break;
                        }
                }
                if (tj == NULL)
                        TAILQ_INSERT_TAIL(&sleeping, j, tq);
                j->queue = &sleeping;
        }
        return 1;
}

/*
 * Remove any processes from the hash that correspond to a jail.
 */
static void
clear_procs(struct cfjail *j)
{
        struct kevent ke;
        struct phash *ph, *tph;
        int i;

        j->nprocs = 0;
        for (i = 0; i < PHASH_SIZE; i++)
                LIST_FOREACH_SAFE(ph, &phash[i], le, tph)
                        if (ph->j == j) {
                                EV_SET(&ke, ph->pid, EVFILT_PROC, EV_DELETE,
                                    NOTE_EXIT, 0, NULL);
                                (void)kevent(kq, &ke, 1, NULL, 0, NULL);
                                LIST_REMOVE(ph, le);
                                free(ph);
                        }
}

/*
 * Find the jail that corresponds to an exited process.
 */
static struct cfjail *
find_proc(pid_t pid)
{
        struct cfjail *j;
        struct phash *ph;

        LIST_FOREACH(ph, &phash[pid % PHASH_SIZE], le)
                if (ph->pid == pid) {
                        j = ph->j;
                        LIST_REMOVE(ph, le);
                        free(ph);
                        return --j->nprocs ? NULL : j;
                }
        return NULL;
}

/*
 * Send SIGTERM to all processes in a jail and wait for them to die.
 */
static int
term_procs(struct cfjail *j)
{
        struct kinfo_proc *ki;
        int i, noted, pcnt, timeout;

        static kvm_t *kd;

        if (!int_param(j->intparams[IP_STOP_TIMEOUT], &timeout))
                timeout = DEFAULT_STOP_TIMEOUT;
        else if (timeout == 0)
                return 0;

        if (kd == NULL) {
                kd = kvm_open(NULL, NULL, NULL, O_RDONLY, NULL);
                if (kd == NULL)
                        return 0;
        }

        ki = kvm_getprocs(kd, KERN_PROC_PROC, 0, &pcnt);
        if (ki == NULL)
                return 0;
        noted = 0;
        for (i = 0; i < pcnt; i++)
                if (ki[i].ki_jid == j->jid &&
                    kill(ki[i].ki_pid, SIGTERM) == 0) {
                        (void)add_proc(j, ki[i].ki_pid);
                        if (verbose > 0) {
                                if (!noted) {
                                        noted = 1;
                                        jail_note(j, "sent SIGTERM to:");
                                }
                                printf(" %d", ki[i].ki_pid);
                        }
                }
        if (noted)
                printf("\n");
        if (j->nprocs > 0) {
                clock_gettime(CLOCK_REALTIME, &j->timeout);
                j->timeout.tv_sec += timeout;
                return 1;
        }
        return 0;
}

/*
 * Look up a user in the passwd and login.conf files.
 */
static int
get_user_info(struct cfjail *j, const char *username,
    const struct passwd **pwdp, login_cap_t **lcapp)
{
        const struct passwd *pwd;

        errno = 0;
        *pwdp = pwd = username ? getpwnam(username) : getpwuid(getuid());
        if (pwd == NULL) {
                if (errno)
                        jail_warnx(j, "getpwnam%s%s: %s", username ? " " : "",
                            username ? username : "", strerror(errno));
                else if (username)
                        jail_warnx(j, "%s: no such user", username);
                else
                        jail_warnx(j, "unknown uid %d", getuid());
                return -1;
        }
        *lcapp = login_getpwclass(pwd);
        if (*lcapp == NULL) {
                jail_warnx(j, "getpwclass %s: %s", pwd->pw_name,
                    strerror(errno));
                return -1;
        }
        /* Set the groups while the group file is still available */
        if (initgroups(pwd->pw_name, pwd->pw_gid) < 0) {
                jail_warnx(j, "initgroups %s: %s", pwd->pw_name,
                    strerror(errno));
                return -1;
        }
        return 0;
}

/*
 * Make sure a mount or consolelog path is a valid absolute pathname
 * with no symlinks.
 */
static int
check_path(struct cfjail *j, const char *pname, const char *path, int isfile,
    const char *umount_type)
{
        struct stat st, mpst;
        struct statfs stfs;
        char *tpath, *p;
        const char *jailpath;
        size_t jplen;

        if (path[0] != '/') {
                jail_warnx(j, "%s: %s: not an absolute pathname",
                    pname, path);
                return -1;
        }
        /*
         * Only check for symlinks in components below the jail's path,
         * since that's where the security risk lies.
         */
        jailpath = string_param(j->intparams[KP_PATH]);
        if (jailpath == NULL)
                jailpath = "";
        jplen = strlen(jailpath);
        if (!strncmp(path, jailpath, jplen) && path[jplen] == '/') {
                tpath = alloca(strlen(path) + 1);
                strcpy(tpath, path);
                for (p = tpath + jplen; p != NULL; ) {
                        p = strchr(p + 1, '/');
                        if (p)
                                *p = '\0';
                        if (lstat(tpath, &st) < 0) {
                                if (errno == ENOENT && isfile && !p)
                                        break;
                                jail_warnx(j, "%s: %s: %s", pname, tpath,
                                    strerror(errno));
                                return -1;
                        }
                        if (S_ISLNK(st.st_mode)) {
                                jail_warnx(j, "%s: %s is a symbolic link",
                                    pname, tpath);
                                return -1;
                        }
                        if (p)
                                *p = '/';
                }
        }
        if (umount_type != NULL) {
                if (stat(path, &st) < 0 || statfs(path, &stfs) < 0) {
                        jail_warnx(j, "%s: %s: %s", pname, path,
                            strerror(errno));
                        return -1;
                }
                if (stat(stfs.f_mntonname, &mpst) < 0) {
                        jail_warnx(j, "%s: %s: %s", pname, stfs.f_mntonname,
                            strerror(errno));
                        return -1;
                }
                if (st.st_ino != mpst.st_ino) {
                        jail_warnx(j, "%s: %s: not a mount point",
                            pname, path);
                        return -1;
                }
                if (strcmp(stfs.f_fstypename, umount_type)) {
                        jail_warnx(j, "%s: %s: not a %s mount",
                            pname, path, umount_type);
                        return -1;
                }
        }
        return 0;
}