daemons/syseventconfd/syseventconfd.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * syseventconfd - The sysevent conf daemon
 *
 * This daemon is a companion to the sysevent_conf_mod module.
 *
 * The sysevent_conf_mod module receives events from syseventd,
 * and compares those events against event specs in the
 * sysevent.conf files.  For each matching event spec, the
 * specified command is invoked.
 *
 * This daemon manages the fork/exec's on behalf of sysevent_conf_mod.
 * The events and associated nvlist are delivered via a door upcall
 * from sysevent_conf_mod.  Arriving events are queued, and the
 * main thread of this daemon dequeues events one by one, and
 * builds the necessary arguments to fork/exec the command.
 *
 * Since sysevent_conf_mod is running in the context of syseventd,
 * invoking the fork/exec from that module blocks the door upcalls
 * from the kernel delivering events to syseventd.  We avoid a
 * major performance bottleneck in this fashion.
 */

#include <stdio.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <strings.h>
#include <unistd.h>
#include <synch.h>
#include <syslog.h>
#include <pthread.h>
#include <door.h>
#include <libsysevent.h>
#include <limits.h>
#include <locale.h>
#include <sys/modctl.h>
#include <sys/stat.h>
#include <sys/systeminfo.h>
#include <sys/wait.h>

#include "syseventconfd.h"
#include "syseventconfd_door.h"
#include "message_confd.h"


static int  debug_level = 0;
static char *root_dir   = "";   /* Relative root for lock and door */
static char *prog;

static struct cmd   *cmd_list;
static struct cmd   *cmd_tail;

static mutex_t      cmd_list_lock;
static cond_t       cmd_list_cv;

extern char *optarg;

/*
 * Support for door server thread handling
 */
#define MAX_SERVER_THREADS  1

static mutex_t create_cnt_lock;
static int cnt_servers = 0;


static void
usage() {
    (void) fprintf(stderr, "usage: syseventconfd [-d <debug_level>]\n");
    exit(2);
}


static void
set_root_dir(char *dir)
{
    root_dir = malloc(strlen(dir) + 1);
    if (root_dir == NULL) {
        syserrmsg(INIT_ROOT_DIR_ERR, strerror(errno));
        exit(2);
    }
    (void) strcpy(root_dir, dir);
}


int
main(int argc, char **argv)
{
    int c;
    int fd;
    sigset_t set;
    struct cmd *cmd;

    (void) setlocale(LC_ALL, "");
    (void) textdomain(TEXT_DOMAIN);

    if (getuid() != 0) {
        (void) fprintf(stderr, "Must be root to run syseventconfd\n");
        exit(1);
    }

    if ((prog = strrchr(argv[0], '/')) == NULL) {
        prog = argv[0];
    } else {
        prog++;
    }

    if ((c = getopt(argc, argv, "d:r:")) != EOF) {
        switch (c) {
        case 'd':
            debug_level = atoi(optarg);
            break;
        case 'r':
            /*
             * Private flag for suninstall to run
             * daemon during install.
             */
            set_root_dir(optarg);
            break;
        case '?':
        default:
            usage();
        }
    }


    if (fork()) {
        exit(0);
    }

    (void) chdir("/");

    (void) setsid();
    if (debug_level <= 1) {
        closefrom(0);
        fd = open("/dev/null", 0);
        (void) dup2(fd, 1);
        (void) dup2(fd, 2);
    }

    openlog("syseventconfd", LOG_PID, LOG_DAEMON);

    printmsg(1,
        "syseventconfd started, debug level = %d\n", debug_level);

    /*
     * Block all signals to all threads include the main thread.
     * The sigwait_thr thread will catch and process all signals.
     */
    (void) sigfillset(&set);
    (void) thr_sigsetmask(SIG_BLOCK, &set, NULL);

    /* Create signal catching thread */
    if (thr_create(NULL, NULL, (void *(*)(void *))sigwait_thr,
        (void *)NULL, 0, NULL) < 0) {
        syserrmsg(INIT_THR_CREATE_ERR, strerror(errno));
        exit(2);
    }

    /*
     * Init mutex and list of cmds to be fork/exec'ed
     * This is multi-threaded so the fork/exec can be
     * done without blocking the door upcall.
     */
    cmd_list = NULL;
    cmd_tail = NULL;

    (void) mutex_init(&create_cnt_lock, USYNC_THREAD, NULL);
    (void) mutex_init(&cmd_list_lock, USYNC_THREAD, NULL);
    (void) cond_init(&cmd_list_cv, USYNC_THREAD, NULL);

    /*
     * Open communication channel from sysevent_conf_mod
     */
    if (open_channel() == NULL) {
        exit(1);
    }

    /*
     * main thread to wait for events to arrive and be placed
     * on the queue.  As events are queued, dequeue them
     * here and invoke the associated fork/exec.
     */
    (void) mutex_lock(&cmd_list_lock);
    for (;;) {
        while (cmd_list == NULL)
            (void) cond_wait(&cmd_list_cv, &cmd_list_lock);

        cmd = cmd_list;
        cmd_list = cmd->cmd_next;
        if (cmd_list == NULL)
            cmd_tail = NULL;

        (void) mutex_unlock(&cmd_list_lock);
        exec_cmd(cmd);
        free_cmd(cmd);
        (void) mutex_lock(&cmd_list_lock);
    }
    /* NOTREACHED */
    return (0);
}

/*
 * Events sent via the door call from sysevent_conf_mod arrive
 * here.  Queue each event for the main thread to invoke, and
 * return.  We want to avoid doing the fork/exec while in the
 * context of the door call.
 */
/*ARGSUSED*/
static void
event_handler(sysevent_t *event)
{
    nvlist_t    *nvlist;
    struct cmd  *cmd;

    nvlist = NULL;
    if (sysevent_get_attr_list(event, &nvlist) != 0) {
        syslog(LOG_ERR, NO_NVLIST_ERR);
        return;
    }

    if ((cmd = alloc_cmd(nvlist)) != NULL) {
        (void) mutex_lock(&cmd_list_lock);
        if (cmd_list == NULL) {
            cmd_list = cmd;
            cmd_tail = cmd;
        } else {
            cmd_tail->cmd_next = cmd;
            cmd_tail = cmd;
        }
        cmd->cmd_next = NULL;
        (void) cond_signal(&cmd_list_cv);
        (void) mutex_unlock(&cmd_list_lock);
    }

    nvlist_free(nvlist);
}


/*
 * Decode the command, build the exec args and fork/exec the command
 * All command attributes are packed into the nvlist bundled with
 * the delivered event.
 */
static void
exec_cmd(struct cmd *cmd)
{
    char        *path;
    char        *cmdline;
    uid_t       uid;
    gid_t       gid;
    char        *file;
    int     line;
    char        *user;
    arg_t       *args;
    pid_t       pid;
    char        *lp;
    char        *p;
    int     i;
    sigset_t    set, prior_set;

    if (nvlist_lookup_string(cmd->cmd_nvlist, "user", &user) != 0) {
        syslog(LOG_ERR, NVLIST_FORMAT_ERR, "user");
        return;
    }
    if (nvlist_lookup_string(cmd->cmd_nvlist, "file", &file) != 0) {
        syslog(LOG_ERR, NVLIST_FORMAT_ERR, "file");
        return;
    }

    if (nvlist_lookup_string(cmd->cmd_nvlist, "path", &path) != 0) {
        syslog(LOG_ERR, NVLIST_FILE_LINE_FORMAT_ERR, "path");
        return;
    }
    if (nvlist_lookup_string(cmd->cmd_nvlist, "cmd", &cmdline) != 0) {
        syslog(LOG_ERR, NVLIST_FILE_LINE_FORMAT_ERR, "cmd");
        return;
    }
    if (nvlist_lookup_int32(cmd->cmd_nvlist, "line", &line) != 0) {
        syslog(LOG_ERR, NVLIST_FILE_LINE_FORMAT_ERR, "line");
        return;
    }
    if (nvlist_lookup_int32(cmd->cmd_nvlist, "uid", (int *)&uid) == 0) {
        if (nvlist_lookup_int32(cmd->cmd_nvlist,
            "gid", (int *)&gid) != 0) {
            syslog(LOG_ERR, NVLIST_FILE_LINE_FORMAT_ERR, "gid");
            return;
        }
    } else {
        uid = 0;
        gid = 0;
    }

    args = init_arglist(32);

    lp = cmdline;
    while ((p = next_arg(&lp)) != NULL) {
        if (add_arg(args, p)) {
            free_arglist(args);
            return;
        }
    }

    if (debug_level >= DBG_EXEC) {
        printmsg(DBG_EXEC, "path=%s\n", path);
        printmsg(DBG_EXEC, "cmd=%s\n", cmdline);
    }

    if (debug_level >= DBG_EXEC_ARGS) {
        for (i = 0; i < args->arg_nargs; i++) {
            printmsg(DBG_EXEC_ARGS,
                "arg[%d]: '%s'\n", i, args->arg_args[i]);
        }
    }

    (void) sigprocmask(SIG_SETMASK, NULL, &set);
    (void) sigaddset(&set, SIGCHLD);
    (void) sigprocmask(SIG_SETMASK, &set, &prior_set);

again:
    if ((pid = fork1()) == (pid_t)-1) {
        if (errno == EINTR)
            goto again;
        syslog(LOG_ERR, CANNOT_FORK_ERR, strerror(errno));
        free_arglist(args);
        return;
    }
    if (pid != (pid_t)0) {
        (void) sigprocmask(SIG_SETMASK, &prior_set, NULL);
        free_arglist(args);
        return;
    }

    /*
     * The child
     */
    (void) close(0);
    (void) close(1);
    (void) close(2);
    (void) open("/dev/null", O_RDONLY);
    (void) dup2(0, 1);
    (void) dup2(0, 2);

    if (uid != (uid_t)0) {
        i = setgid(gid);
        if (i == 0)
            i = setuid(uid);
        if (i != 0) {
            syslog(LOG_ERR, SETUID_ERR,
                file, line, user, strerror(errno));
            _exit(0);
        }
    }

    /*
     * Unblock all signals in the child
     */
    (void) sigprocmask(SIG_UNBLOCK, &prior_set, NULL);

    if (execv(path, args->arg_args) == -1) {
        syslog(LOG_ERR, CANNOT_EXEC_ERR,
            path, strerror(errno));
        _exit(0);
    }
}


/*
 * Thread to handle in-coming signals
 */
static void
sigwait_thr()
{
    int sig;
    sigset_t signal_set;

    /*
     * SIGCHLD is ignored by default, and we need to handle this
     * signal to reap the status of all children spawned by
     * this daemon.
     */
    (void) sigset(SIGCHLD, reapchild);

    for (;;) {
        (void) sigfillset(&signal_set);
        if (sigwait(&signal_set, &sig) == 0) {
            /*
             * Block all signals until the signal handler completes
             */
            (void) sigfillset(&signal_set);
            (void) thr_sigsetmask(SIG_BLOCK, &signal_set, NULL);

            if (sig == SIGCHLD) {
                reapchild(sig);
            } else {
                flt_handler(sig);
            }
        }
    }
    /* NOTREACHED */
}


/*
 * reapchild - reap the status of each child as it exits
 */
/*ARGSUSED*/
static void
reapchild(int sig)
{
    siginfo_t info;
    char *signam;
    int err;

    for (;;) {
        (void) memset(&info, 0, sizeof (info));
        err = waitid(P_ALL, 0, &info, WNOHANG|WEXITED);
        if (err == -1) {
            if (errno != EINTR && errno != EAGAIN)
                return;
        } else if (info.si_pid == 0) {
            return;
        }

        if (debug_level >= DBG_CHILD) {
            printmsg(DBG_CHILD, CHILD_EXIT_STATUS_ERR,
                info.si_pid, info.si_status);
        }

        if (info.si_status) {
            if (info.si_code == CLD_EXITED) {
                syserrmsg(CHILD_EXIT_STATUS_ERR,
                    info.si_pid, info.si_status);
            } else {
                signam = strsignal(info.si_status);
                if (signam == NULL)
                    signam = "";
                if (info.si_code == CLD_DUMPED) {
                    syserrmsg(
                        CHILD_EXIT_CORE_ERR,
                        info.si_pid, signam);
                } else {
                    syserrmsg(
                        CHILD_EXIT_SIGNAL_ERR,
                        info.si_pid, signam);
                }
            }
        }
    }
}


/*
 * Fault handler for other signals caught
 */
/*ARGSUSED*/
static void
flt_handler(int sig)
{
    struct sigaction act;

    (void) memset(&act, 0, sizeof (act));
    act.sa_handler = SIG_DFL;
    act.sa_flags = SA_RESTART;
    (void) sigfillset(&act.sa_mask);
    (void) sigaction(sig, &act, NULL);

    switch (sig) {
        case SIGINT:
        case SIGSTOP:
        case SIGTERM:
        case SIGHUP:
            exit(1);
            /*NOTREACHED*/
    }
}


static arg_t *
init_arglist(int hint)
{
    arg_t   *arglist;

    if ((arglist = sc_malloc(sizeof (arg_t))) == NULL)
        return (NULL);
    arglist->arg_args = NULL;
    arglist->arg_nargs = 0;
    arglist->arg_alloc = 0;
    arglist->arg_hint = hint;
    return (arglist);
}


static void
free_arglist(arg_t *arglist)
{
    if (arglist->arg_args) {
        free(arglist->arg_args);
    }
    free(arglist);
}


static int
add_arg(arg_t *arglist, char *arg)
{
    char    **new_args;
    int len;

    len = arglist->arg_nargs + 2;
    if (arglist->arg_alloc < len) {
        arglist->arg_alloc = len + arglist->arg_hint;
        new_args = (arglist->arg_nargs == 0) ?
            sc_malloc(arglist->arg_alloc * sizeof (char **)) :
            sc_realloc(arglist->arg_args,
                arglist->arg_alloc * sizeof (char **));
        if (new_args == NULL)
            return (1);
        arglist->arg_args = new_args;
    }

    arglist->arg_args[arglist->arg_nargs++] = arg;
    arglist->arg_args[arglist->arg_nargs] = NULL;

    return (0);
}

/*
 * next_arg() is used to break up a command line
 * into the arguments for execv(2).  Break up
 * arguments separated by spaces, but respecting
 * single/double quotes.
 */
static char *
next_arg(char **cpp)
{
    char    *cp = *cpp;
    char    *start;
    char    quote;

    while (*cp == ' ' || *cp == '\t')
        cp++;
    if (*cp == 0) {
        *cpp = 0;
        return (NULL);
    }
    start = cp;
    while (*cp && *cp != ' ' && *cp != '\t') {
        if (*cp == '"' || *cp == '\'') {
            quote = *cp++;
            while (*cp && *cp != quote) {
                cp++;
            }
            if (*cp == 0) {
                *cpp = 0;
                return (NULL);
            } else {
                cp++;
            }
        } else {
            cp++;
        }
    }
    if (*cp != 0)
        *cp++ = 0;
    *cpp = cp;
    return (start);
}


static struct cmd *
alloc_cmd(nvlist_t *nvlist)
{
    struct cmd *cmd;

    cmd = sc_malloc(sizeof (struct cmd));
    if (cmd) {
        if (nvlist_dup(nvlist, &cmd->cmd_nvlist, 0) != 0) {
            syslog(LOG_ERR, OUT_OF_MEMORY_ERR);
            free(cmd);
            return (NULL);
        }
    }
    return (cmd);
}

static void
free_cmd(struct cmd *cmd)
{
    nvlist_free(cmd->cmd_nvlist);
    free(cmd);
}


static void *
sc_malloc(size_t n)
{
    void *p;

    p = malloc(n);
    if (p == NULL) {
        syslog(LOG_ERR, OUT_OF_MEMORY_ERR);
    }
    return (p);
}

static void *
sc_realloc(void *p, size_t n)
{
    p = realloc(p, n);
    if (p == NULL) {
        syslog(LOG_ERR, OUT_OF_MEMORY_ERR);
    }
    return (p);
}


/*
 * syserrsg - print error messages to the terminal if not
 *          yet daemonized or to syslog.
 */
/*PRINTFLIKE1*/
static void
syserrmsg(char *message, ...)
{
    va_list ap;

    va_start(ap, message);
    (void) vsyslog(LOG_ERR, message, ap);
    va_end(ap);
}

/*
 * printmsg -  print messages to the terminal or to syslog
 *          the following levels are implemented:
 */
/*PRINTFLIKE2*/
static void
printmsg(int level, char *message, ...)
{
    va_list ap;

    if (level > debug_level) {
        return;
    }

    va_start(ap, message);
    (void) syslog(LOG_DEBUG, "%s[%ld]: ", prog, getpid());
    (void) vsyslog(LOG_DEBUG, message, ap);
    va_end(ap);
}

/* ARGSUSED */
static void *
create_door_thr(void *arg)
{
    (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
    (void) door_return(NULL, 0, NULL, 0);
    return (NULL);
}

/*
 * Control creation of door server threads
 *
 * If first creation of server thread fails there is nothing
 * we can do about. Doors would not work.
 */
/* ARGSUSED */
static void
mk_thr_pool(door_info_t *dip)
{
    (void) mutex_lock(&create_cnt_lock);
    if (++cnt_servers > MAX_SERVER_THREADS) {
        cnt_servers--;
        (void) mutex_unlock(&create_cnt_lock);
        return;
    }
    (void) mutex_unlock(&create_cnt_lock);

    (void) thr_create(NULL, 0, create_door_thr, NULL,
        THR_BOUND|THR_DETACHED, NULL);
}

static sysevent_handle_t *
open_channel()
{
    char    door_path[MAXPATHLEN];
    const char *subclass_list;
    sysevent_handle_t *handle;

    if (snprintf(door_path, sizeof (door_path), "%s/%s",
        root_dir, SYSEVENTCONFD_SERVICE_DOOR) >= sizeof (door_path)) {
        syserrmsg(CHANNEL_OPEN_ERR);
        return (NULL);
    }

    /*
     * Setup of door server create function to limit the
     * amount of door servers
     */
    (void) door_server_create(mk_thr_pool);

    handle = sysevent_open_channel_alt(door_path);
    if (handle == NULL) {
        syserrmsg(CHANNEL_OPEN_ERR);
        return (NULL);
    }
    if (sysevent_bind_subscriber(handle, event_handler) != 0) {
        syserrmsg(CHANNEL_BIND_ERR);
        sysevent_close_channel(handle);
        return (NULL);
    }
    subclass_list = EC_SUB_ALL;
    if (sysevent_register_event(handle, EC_ALL, &subclass_list, 1)
        != 0) {
        syserrmsg(CHANNEL_BIND_ERR);
        (void) sysevent_unbind_subscriber(handle);
        (void) sysevent_close_channel(handle);
        return (NULL);
    }
    return (handle);
}