/*
 * 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.
 * Copyright 2011 Joyent, Inc.  All rights reserved.
 */

/*
 * 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;
}

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

/*
 * Initialize each running zone.
 */
static int
dlmgmt_allzones_init(void)
{
        int             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++) {
                int res;
                zone_status_t status;

                /*
                 * Skip over zones that have gone away or are going down
                 * since we got the list.  Process all zones in the list,
                 * logging errors for any that failed.
                 */
                if (zone_getattr(zids[i], ZONE_ATTR_STATUS, &status,
                    sizeof (status)) < 0) {
                        continue;
                }
                switch (status) {
                        case ZONE_IS_SHUTTING_DOWN:
                        case ZONE_IS_EMPTY:
                        case ZONE_IS_DOWN:
                        case ZONE_IS_DYING:
                        case ZONE_IS_DEAD:
                        case ZONE_IS_INITIALIZED:
                        case ZONE_IS_UNINITIALIZED:
                                continue;
                        default:
                                break;
                }
                if ((res = dlmgmt_zone_init(zids[i])) != 0) {
                        (void) fprintf(stderr, "zone (%ld) init error %s",
                            zids[i], strerror(res));
                        dlmgmt_log(LOG_ERR, "zone (%d) init error %s",
                            zids[i], strerror(res));
                }
        }
        free(zids);
        return (0);
}

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(7) 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;

        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();
        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);
}