cmd/dlmgmtd/dlmgmt_main.c

	dlmgmt_main.c revision 6ba597c56d749c61b4f783157f63196d7b2445f0
/*
 * 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 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * The dlmgmtd daemon is started by the datalink-management SMF service.
 * This daemon is used to manage <link name, linkid> mapping and the
 * persistent datalink configuration.
 *
 * Today, the <link name, linkid> mapping and the persistent configuration
 * of datalinks is kept in /etc/dladm/datalink.conf, and the daemon keeps
 * a copy of the datalinks in the memory (see dlmgmt_id_avl and
 * dlmgmt_name_avl). The active <link name, linkid> mapping is kept in
 * /etc/svc/volatile/dladm cache file, so that the mapping can be recovered
 * when dlmgmtd exits for some reason (e.g., when dlmgmtd is accidentally
 * killed).
 */

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <priv.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <syslog.h>
#include <zone.h>
#include <sys/dld.h>
#include <sys/dld_ioc.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <unistd.h>
#include <libdladm_impl.h>
#include <libdlmgmt.h>
#include "dlmgmt_impl.h"

const char      *progname;
boolean_t       debug;
static int      pfds[2];
/*
 * This file descriptor to DLMGMT_DOOR cannot be in the libdladm
 * handle because the door isn't created when the handle is created.
 */
static int      dlmgmt_door_fd = -1;

/*
 * This libdladm handle is global so that dlmgmt_upcall_linkprop_init() can
 * pass to libdladm.  The handle is opened with "ALL" privileges, before
 * privileges are dropped in dlmgmt_drop_privileges().  It is not able to open
 * DLMGMT_DOOR at that time as it hasn't been created yet.  This door in the
 * handle is opened in the first call to dladm_door_fd().
 */
dladm_handle_t      dld_handle = NULL;

static void     dlmgmtd_exit(int);
static int      dlmgmt_init();
static void     dlmgmt_fini();
static int      dlmgmt_set_privileges();

static int
dlmgmt_set_doorfd(boolean_t start)
{
    dld_ioc_door_t did;
    int err = 0;

    assert(dld_handle != NULL);

    did.did_start_door = start;

    if (ioctl(dladm_dld_fd(dld_handle), DLDIOC_DOORSERVER, &did) == -1)
        err = errno;

    return (err);
}

static int
dlmgmt_door_init(void)
{
    int err = 0;

    if ((dlmgmt_door_fd = door_create(dlmgmt_handler, NULL,
        DOOR_REFUSE_DESC | DOOR_NO_CANCEL)) == -1) {
        err = errno;
        dlmgmt_log(LOG_ERR, "door_create() failed: %s",
            strerror(err));
        return (err);
    }
    return (err);
}

static void
dlmgmt_door_fini(void)
{
    if (dlmgmt_door_fd == -1)
        return;

    if (door_revoke(dlmgmt_door_fd) == -1) {
        dlmgmt_log(LOG_WARNING, "door_revoke(%s) failed: %s",
            DLMGMT_DOOR, strerror(errno));
    }
    (void) dlmgmt_set_doorfd(B_FALSE);
    dlmgmt_door_fd = -1;
}

int
dlmgmt_door_attach(zoneid_t zoneid, char *rootdir)
{
    int fd;
    int err = 0;
    char    doorpath[MAXPATHLEN];

    (void) snprintf(doorpath, sizeof (doorpath), "%s%s", rootdir,
        DLMGMT_DOOR);

    /*
     * Create the door file for dlmgmtd.
     */
    if ((fd = open(doorpath, O_CREAT|O_RDONLY, 0644)) == -1) {
        err = errno;
        dlmgmt_log(LOG_ERR, "open(%s) failed: %s", doorpath,
            strerror(err));
        return (err);
    }
    (void) close(fd);
    if (chown(doorpath, UID_DLADM, GID_NETADM) == -1)
        return (errno);

    /*
     * fdetach first in case a previous daemon instance exited
     * ungracefully.
     */
    (void) fdetach(doorpath);
    if (fattach(dlmgmt_door_fd, doorpath) != 0) {
        err = errno;
        dlmgmt_log(LOG_ERR, "fattach(%s) failed: %s", doorpath,
            strerror(err));
    } else if (zoneid == GLOBAL_ZONEID) {
        if ((err = dlmgmt_set_doorfd(B_TRUE)) != 0) {
            dlmgmt_log(LOG_ERR, "cannot set kernel doorfd: %s",
                strerror(err));
        }
    }

    return (err);
}

/*
 * Create the /etc/svc/volatile/dladm/ directory if it doesn't exist, load the
 * datalink.conf data for this zone, and create/attach the door rendezvous
 * file.
 */
int
dlmgmt_zone_init(zoneid_t zoneid)
{
    char    rootdir[MAXPATHLEN], tmpfsdir[MAXPATHLEN];
    int err;
    struct stat statbuf;

    if (zoneid == GLOBAL_ZONEID) {
        rootdir[0] = '\0';
    } else if (zone_getattr(zoneid, ZONE_ATTR_ROOT, rootdir,
        sizeof (rootdir)) < 0) {
        return (errno);
    }

    /*
     * Create the DLMGMT_TMPFS_DIR directory.
     */
    (void) snprintf(tmpfsdir, sizeof (tmpfsdir), "%s%s", rootdir,
        DLMGMT_TMPFS_DIR);
    if (stat(tmpfsdir, &statbuf) < 0) {
        if (mkdir(tmpfsdir, (mode_t)0755) < 0)
            return (errno);
    } else if ((statbuf.st_mode & S_IFMT) != S_IFDIR) {
        return (ENOTDIR);
    }

    if ((chmod(tmpfsdir, 0755) < 0) ||
        (chown(tmpfsdir, UID_DLADM, GID_NETADM) < 0)) {
        return (EPERM);
    }

    if ((err = dlmgmt_db_init(zoneid)) != 0)
        return (err);
    return (dlmgmt_door_attach(zoneid, rootdir));
}

/*
 * Initialize each running zone.
 */
static int
dlmgmt_allzones_init(void)
{
    int     err, i;
    zoneid_t    *zids = NULL;
    uint_t      nzids, nzids_saved;

    if (zone_list(NULL, &nzids) != 0)
        return (errno);
again:
    nzids *= 2;
    if ((zids = malloc(nzids * sizeof (zoneid_t))) == NULL)
        return (errno);
    nzids_saved = nzids;
    if (zone_list(zids, &nzids) != 0) {
        free(zids);
        return (errno);
    }
    if (nzids > nzids_saved) {
        free(zids);
        goto again;
    }

    for (i = 0; i < nzids; i++) {
        if ((err = dlmgmt_zone_init(zids[i])) != 0)
            break;
    }
    free(zids);
    return (err);
}

static int
dlmgmt_init(void)
{
    int err;
    char    *fmri, *c;
    char    filename[MAXPATHLEN];

    if (dladm_open(&dld_handle) != DLADM_STATUS_OK) {
        dlmgmt_log(LOG_ERR, "dladm_open() failed");
        return (EPERM);
    }

    if (signal(SIGTERM, dlmgmtd_exit) == SIG_ERR ||
        signal(SIGINT, dlmgmtd_exit) == SIG_ERR) {
        err = errno;
        dlmgmt_log(LOG_ERR, "signal() for SIGTERM/INT failed: %s",
            strerror(err));
        return (err);
    }

    /*
     * First derive the name of the cache file from the FMRI name. This
     * cache name is used to keep active datalink configuration.
     */
    if (debug) {
        (void) snprintf(cachefile, MAXPATHLEN, "%s/%s%s",
            DLMGMT_TMPFS_DIR, progname, ".debug.cache");
    } else {
        if ((fmri = getenv("SMF_FMRI")) == NULL) {
            dlmgmt_log(LOG_ERR, "dlmgmtd is an smf(5) managed "
                "service and should not be run from the command "
                "line.");
            return (EINVAL);
        }

        /*
         * The FMRI name is in the form of
         * svc:/service/service:instance.  We need to remove the
         * prefix "svc:/" and replace '/' with '-'.  The cache file
         * name is in the form of "service:instance.cache".
         */
        if ((c = strchr(fmri, '/')) != NULL)
            c++;
        else
            c = fmri;
        (void) snprintf(filename, MAXPATHLEN, "%s.cache", c);
        c = filename;
        while ((c = strchr(c, '/')) != NULL)
            *c = '-';

        (void) snprintf(cachefile, MAXPATHLEN, "%s/%s",
            DLMGMT_TMPFS_DIR, filename);
    }

    dlmgmt_linktable_init();
    if ((err = dlmgmt_door_init()) != 0)
        goto done;

    /*
     * Load datalink configuration and create dlmgmtd door files for all
     * currently running zones.
     */
    if ((err = dlmgmt_allzones_init()) != 0)
        dlmgmt_door_fini();

done:
    if (err != 0)
        dlmgmt_linktable_fini();
    return (err);
}

static void
dlmgmt_fini(void)
{
    dlmgmt_door_fini();
    dlmgmt_linktable_fini();
    if (dld_handle != NULL) {
        dladm_close(dld_handle);
        dld_handle = NULL;
    }
}

/*
 * This is called by the child process to inform the parent process to
 * exit with the given return value.
 */
static void
dlmgmt_inform_parent_exit(int rv)
{
    if (debug)
        return;

    if (write(pfds[1], &rv, sizeof (int)) != sizeof (int)) {
        dlmgmt_log(LOG_WARNING,
            "dlmgmt_inform_parent_exit() failed: %s", strerror(errno));
        (void) close(pfds[1]);
        exit(EXIT_FAILURE);
    }
    (void) close(pfds[1]);
}

/*ARGSUSED*/
static void
dlmgmtd_exit(int signo)
{
    (void) close(pfds[1]);
    dlmgmt_fini();
    exit(EXIT_FAILURE);
}

static void
usage(void)
{
    (void) fprintf(stderr, "Usage: %s [-d]\n", progname);
    exit(EXIT_FAILURE);
}

/*
 * Restrict privileges to only those needed.
 */
int
dlmgmt_drop_privileges(void)
{
    priv_set_t  *pset;
    priv_ptype_t    ptype;
    zoneid_t    zoneid = getzoneid();
    int     err = 0;

    if ((pset = priv_allocset()) == NULL)
        return (errno);

    /*
     * The global zone needs PRIV_PROC_FORK so that it can fork() when it
     * issues db ops in non-global zones, PRIV_SYS_CONFIG to post
     * sysevents, and PRIV_SYS_DL_CONFIG to initialize link properties in
     * dlmgmt_upcall_linkprop_init().
     *
     * We remove non-basic privileges from the permitted (and thus
     * effective) set.  When executing in a non-global zone, dlmgmtd
     * only needs to read and write to files that it already owns.
     */
    priv_basicset(pset);
    (void) priv_delset(pset, PRIV_PROC_EXEC);
    (void) priv_delset(pset, PRIV_PROC_INFO);
    (void) priv_delset(pset, PRIV_PROC_SESSION);
    (void) priv_delset(pset, PRIV_FILE_LINK_ANY);
    if (zoneid == GLOBAL_ZONEID) {
        ptype = PRIV_EFFECTIVE;
        if (priv_addset(pset, PRIV_SYS_CONFIG) == -1 ||
            priv_addset(pset, PRIV_SYS_DL_CONFIG) == -1)
            err = errno;
    } else {
        (void) priv_delset(pset, PRIV_PROC_FORK);
        ptype = PRIV_PERMITTED;
    }
    if (err == 0 && setppriv(PRIV_SET, ptype, pset) == -1)
        err = errno;
done:
    priv_freeset(pset);
    return (err);
}

int
dlmgmt_elevate_privileges(void)
{
    priv_set_t  *privset;
    int     err = 0;

    if ((privset = priv_str_to_set("zone", ",", NULL)) == NULL)
        return (errno);
    if (setppriv(PRIV_SET, PRIV_EFFECTIVE, privset) == -1)
        err = errno;
    priv_freeset(privset);
    return (err);
}

/*
 * Set the uid of this daemon to the "dladm" user and drop privileges to only
 * those needed.
 */
static int
dlmgmt_set_privileges(void)
{
    int err;

    (void) setgroups(0, NULL);
    if (setegid(GID_NETADM) == -1 || seteuid(UID_DLADM) == -1)
        err = errno;
    else
        err = dlmgmt_drop_privileges();
done:
    return (err);
}

/*
 * Keep the pfds fd open, close other fds.
 */
/*ARGSUSED*/
static int
closefunc(void *arg, int fd)
{
    if (fd != pfds[1])
        (void) close(fd);
    return (0);
}

static boolean_t
dlmgmt_daemonize(void)
{
    pid_t pid;
    int rv;

    if (pipe(pfds) < 0) {
        (void) fprintf(stderr, "%s: pipe() failed: %s\n",
            progname, strerror(errno));
        exit(EXIT_FAILURE);
    }

    if ((pid = fork()) == -1) {
        (void) fprintf(stderr, "%s: fork() failed: %s\n",
            progname, strerror(errno));
        exit(EXIT_FAILURE);
    } else if (pid > 0) { /* Parent */
        (void) close(pfds[1]);

        /*
         * Read the child process's return value from the pfds.
         * If the child process exits unexpected, read() returns -1.
         */
        if (read(pfds[0], &rv, sizeof (int)) != sizeof (int)) {
            (void) kill(pid, SIGKILL);
            rv = EXIT_FAILURE;
        }

        (void) close(pfds[0]);
        exit(rv);
    }

    /* Child */
    (void) close(pfds[0]);
    (void) setsid();

    /*
     * Close all files except pfds[1].
     */
    (void) fdwalk(closefunc, NULL);
    (void) chdir("/");
    openlog(progname, LOG_PID, LOG_DAEMON);
    return (B_TRUE);
}

int
main(int argc, char *argv[])
{
    int opt, err;

    progname = strrchr(argv[0], '/');
    if (progname != NULL)
        progname++;
    else
        progname = argv[0];

    /*
     * Process options.
     */
    while ((opt = getopt(argc, argv, "d")) != EOF) {
        switch (opt) {
        case 'd':
            debug = B_TRUE;
            break;
        default:
            usage();
        }
    }

    if (!debug && !dlmgmt_daemonize())
        return (EXIT_FAILURE);

    if ((err = dlmgmt_init()) != 0) {
        dlmgmt_log(LOG_ERR, "unable to initialize daemon: %s",
            strerror(err));
        goto child_out;
    } else if ((err = dlmgmt_set_privileges()) != 0) {
        dlmgmt_log(LOG_ERR, "unable to set daemon privileges: %s",
            strerror(err));
        dlmgmt_fini();
        goto child_out;
    }

    /*
     * Inform the parent process that it can successfully exit.
     */
    dlmgmt_inform_parent_exit(EXIT_SUCCESS);

    for (;;)
        (void) pause();

child_out:
    /* return from main() forcibly exits an MT process */
    dlmgmt_inform_parent_exit(EXIT_FAILURE);
    return (EXIT_FAILURE);
}