utils/statd/sm-notify.c

   1 /*
   2  * Send NSM notify calls to all hosts listed in /var/lib/sm
   3  *
   4  * Copyright (C) 2004-2006 Olaf Kirch <okir@suse.de>
   5  */
   6
   7 #include <sys/types.h>
   8 #include <sys/socket.h>
   9 #include <sys/stat.h>
  10 #include <sys/poll.h>
  11 #include <sys/param.h>
  12 #include <sys/syslog.h>
  13 #include <arpa/inet.h>
  14 #include <dirent.h>
  15 #include <time.h>
  16 #include <stdio.h>
  17 #include <getopt.h>
  18 #include <stdlib.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <string.h>
  22 #include <stdarg.h>
  23 #include <netdb.h>
  24 #include <errno.h>
  25 #include <grp.h>
  26
  27 #ifndef BASEDIR
  28 # ifdef NFS_STATEDIR
  29 #  define BASEDIR               NFS_STATEDIR
  30 # else
  31 #  define BASEDIR               "/var/lib/nfs"
  32 # endif
  33 #endif
  34
  35 #define DEFAULT_SM_STATE_PATH   BASEDIR "/state"
  36 #define DEFAULT_SM_DIR_PATH     BASEDIR "/sm"
  37 #define DEFAULT_SM_BAK_PATH     DEFAULT_SM_DIR_PATH ".bak"
  38
  39 char *_SM_BASE_PATH = BASEDIR;
  40 char *_SM_STATE_PATH = DEFAULT_SM_STATE_PATH;
  41 char *_SM_DIR_PATH = DEFAULT_SM_DIR_PATH;
  42 char *_SM_BAK_PATH = DEFAULT_SM_BAK_PATH;
  43
  44 #define NSM_PROG        100024
  45 #define NSM_PROGRAM     100024
  46 #define NSM_VERSION     1
  47 #define NSM_TIMEOUT     2
  48 #define NSM_NOTIFY      6
  49 #define NSM_MAX_TIMEOUT 120     /* don't make this too big */
  50 #define MAXMSGSIZE      256
  51
  52 typedef struct sockaddr_storage nsm_address;
  53
  54 struct nsm_host {
  55         struct nsm_host *       next;
  56         char *                  name;
  57         char *                  path;
  58         nsm_address             addr;
  59         struct addrinfo         *ai;
  60         time_t                  last_used;
  61         time_t                  send_next;
  62         unsigned int            timeout;
  63         unsigned int            retries;
  64         unsigned int            xid;
  65 };
  66
  67 static char             nsm_hostname[256];
  68 static uint32_t         nsm_state;
  69 static int              opt_debug = 0;
  70 static int              opt_quiet = 0;
  71 static int              opt_update_state = 1;
  72 static unsigned int     opt_max_retry = 15 * 60;
  73 static char *           opt_srcaddr = 0;
  74 static uint16_t         opt_srcport = 0;
  75 static int              log_syslog = 0;
  76
  77 static unsigned int     nsm_get_state(int);
  78 static void             notify(void);
  79 static void             notify_host(int, struct nsm_host *);
  80 static void             recv_reply(int);
  81 static void             backup_hosts(const char *, const char *);
  82 static void             get_hosts(const char *);
  83 static void             insert_host(struct nsm_host *);
  84 struct nsm_host *       find_host(uint32_t);
  85 static int              addr_get_port(nsm_address *);
  86 static void             addr_set_port(nsm_address *, int);
  87 static struct addrinfo  *host_lookup(int, const char *);
  88 void                    nsm_log(int fac, const char *fmt, ...);
  89 static int              record_pid();
  90 static void             drop_privs(void);
  91
  92 static struct nsm_host *        hosts = NULL;
  93
  94 int
  95 main(int argc, char **argv)
  96 {
  97         int     c;
  98         int     force = 0;
  99
 100         while ((c = getopt(argc, argv, "dm:np:v:qP:f")) != -1) {
 101                 switch (c) {
 102                 case 'f':
 103                         force = 1;
 104                         break;
 105                 case 'd':
 106                         opt_debug++;
 107                         break;
 108                 case 'm':
 109                         opt_max_retry = atoi(optarg) * 60;
 110                         break;
 111                 case 'n':
 112                         opt_update_state = 0;
 113                         break;
 114                 case 'p':
 115                         opt_srcport = atoi(optarg);
 116                         break;
 117                 case 'v':
 118                         opt_srcaddr = optarg;
 119                         break;
 120                 case 'q':
 121                         opt_quiet = 1;
 122                         break;
 123                 case 'P':
 124                         _SM_BASE_PATH = strdup(optarg);
 125                         _SM_STATE_PATH = malloc(strlen(optarg)+1+sizeof("state"));
 126                         _SM_DIR_PATH = malloc(strlen(optarg)+1+sizeof("sm"));
 127                         _SM_BAK_PATH = malloc(strlen(optarg)+1+sizeof("sm.bak"));
 128                         if (_SM_BASE_PATH == NULL ||
 129                             _SM_STATE_PATH == NULL ||
 130                             _SM_DIR_PATH == NULL ||
 131                             _SM_BAK_PATH == NULL) {
 132                                 nsm_log(LOG_WARNING, "unable to allocate memory");
 133                                 exit(1);
 134                         }
 135                         strcat(strcpy(_SM_STATE_PATH, _SM_BASE_PATH), "/state");
 136                         strcat(strcpy(_SM_DIR_PATH, _SM_BASE_PATH), "/sm");
 137                         strcat(strcpy(_SM_BAK_PATH, _SM_BASE_PATH), "/sm.bak");
 138                         break;
 139
 140                 default:
 141                         goto usage;
 142                 }
 143         }
 144
 145         if (optind < argc) {
 146 usage:          fprintf(stderr,
 147                         "Usage: sm-notify [-dfq] [-m max-retry-minutes] [-p srcport]\n"
 148                         "            [-P /path/to/state/directory] [-v my_host_name]\n");
 149                 return 1;
 150         }
 151
 152         if (strcmp(_SM_BASE_PATH, BASEDIR) == 0) {
 153                 if (record_pid() == 0 && force == 0 && opt_update_state == 1)
 154                         /* already run, don't try again */
 155                         exit(0);
 156         }
 157
 158         if (opt_srcaddr) {
 159                 strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname)-1);
 160         } else
 161         if (gethostname(nsm_hostname, sizeof(nsm_hostname)) < 0) {
 162                 perror("gethostname");
 163                 return 1;
 164         }
 165
 166         backup_hosts(_SM_DIR_PATH, _SM_BAK_PATH);
 167         get_hosts(_SM_BAK_PATH);
 168
 169         if (!opt_debug) {
 170                 if (!opt_quiet)
 171                         printf("Backgrounding to notify hosts...\n");
 172
 173                 openlog("sm-notify", LOG_PID, LOG_DAEMON);
 174                 log_syslog = 1;
 175
 176                 if (daemon(0, 0) < 0) {
 177                         nsm_log(LOG_WARNING, "unable to background: %s",
 178                                         strerror(errno));
 179                         return 1;
 180                 }
 181
 182                 close(0);
 183                 close(1);
 184                 close(2);
 185         }
 186
 187         /* Get and update the NSM state. This will call sync() */
 188         nsm_state = nsm_get_state(opt_update_state);
 189
 190         notify();
 191
 192         if (hosts) {
 193                 struct nsm_host *hp;
 194
 195                 while ((hp = hosts) != 0) {
 196                         hosts = hp->next;
 197                         nsm_log(LOG_NOTICE,
 198                                 "Unable to notify %s, giving up",
 199                                 hp->name);
 200                 }
 201                 return 1;
 202         }
 203
 204         return 0;
 205 }
 206
 207 /*
 208  * Notify hosts
 209  */
 210 void
 211 notify(void)
 212 {
 213         nsm_address local_addr;
 214         time_t  failtime = 0;
 215         int     sock = -1;
 216
 217         sock = socket(AF_INET, SOCK_DGRAM, 0);
 218         if (sock < 0) {
 219                 perror("socket");
 220                 exit(1);
 221         }
 222         fcntl(sock, F_SETFL, O_NONBLOCK);
 223
 224         memset(&local_addr, 0, sizeof(local_addr));
 225         local_addr.ss_family = AF_INET; /* Default to IPv4 */
 226
 227         /* Bind source IP if provided on command line */
 228         if (opt_srcaddr) {
 229                 struct addrinfo *ai = host_lookup(AF_INET, opt_srcaddr);
 230                 if (!ai) {
 231                         nsm_log(LOG_WARNING,
 232                                 "Not a valid hostname or address: \"%s\"\n",
 233                                 opt_srcaddr);
 234                         exit(1);
 235                 }
 236                 memcpy(&local_addr, ai->ai_addr, ai->ai_addrlen);
 237                 /* We know it's IPv4 at this point */
 238         }
 239
 240         /* Use source port if provided on the command line,
 241          * otherwise use bindresvport */
 242         if (opt_srcport) {
 243                 addr_set_port(&local_addr, opt_srcport);
 244                 if (bind(sock, (struct sockaddr *) &local_addr, sizeof(local_addr)) < 0) {
 245                         perror("bind");
 246                         exit(1);
 247                 }
 248         } else {
 249                 (void) bindresvport(sock, (struct sockaddr_in *) &local_addr);
 250         }
 251
 252         if (opt_max_retry)
 253                 failtime = time(NULL) + opt_max_retry;
 254
 255         drop_privs();
 256
 257         while (hosts) {
 258                 struct pollfd   pfd;
 259                 time_t          now = time(NULL);
 260                 unsigned int    sent = 0;
 261                 struct nsm_host *hp;
 262                 long            wait;
 263
 264                 if (failtime && now >= failtime)
 265                         break;
 266
 267                 while ((wait = hosts->send_next - now) <= 0) {
 268                         /* Never send more than 10 packets at once */
 269                         if (sent++ >= 10)
 270                                 break;
 271
 272                         /* Remove queue head */
 273                         hp = hosts;
 274                         hosts = hp->next;
 275
 276                         notify_host(sock, hp);
 277
 278                         /* Set the timeout for this call, using an
 279                            exponential timeout strategy */
 280                         wait = hp->timeout;
 281                         if ((hp->timeout <<= 1) > NSM_MAX_TIMEOUT)
 282                                 hp->timeout = NSM_MAX_TIMEOUT;
 283                         hp->send_next = now + wait;
 284                         hp->retries++;
 285
 286                         insert_host(hp);
 287                 }
 288
 289                 nsm_log(LOG_DEBUG, "Host %s due in %ld seconds",
 290                                 hosts->name, wait);
 291
 292                 pfd.fd = sock;
 293                 pfd.events = POLLIN;
 294
 295                 wait *= 1000;
 296                 if (wait < 100)
 297                         wait = 100;
 298                 if (poll(&pfd, 1, wait) != 1)
 299                         continue;
 300
 301                 recv_reply(sock);
 302         }
 303 }
 304
 305 /*
 306  * Send notification to a single host
 307  */
 308 void
 309 notify_host(int sock, struct nsm_host *host)
 310 {
 311         static unsigned int     xid = 0;
 312         nsm_address             dest;
 313         uint32_t                msgbuf[MAXMSGSIZE], *p;
 314         unsigned int            len;
 315
 316         if (!xid)
 317                 xid = getpid() + time(NULL);
 318         if (!host->xid)
 319                 host->xid = xid++;
 320
 321         memset(msgbuf, 0, sizeof(msgbuf));
 322         p = msgbuf;
 323         *p++ = htonl(host->xid);
 324         *p++ = 0;
 325         *p++ = htonl(2);
 326
 327         /* If we retransmitted 4 times, reset the port to force
 328          * a new portmap lookup (in case statd was restarted).
 329          * We also rotate through multiple IP addresses at this
 330          * point.
 331          */
 332         if (host->retries >= 4) {
 333                 struct addrinfo *hold = host->ai;
 334                 struct addrinfo **next = &host->ai;
 335                 *next = hold->ai_next;
 336                 while ( *next )
 337                         next = & (*next)->ai_next;
 338                 *next = hold;
 339                 hold->ai_next = NULL;
 340                 memcpy(&host->addr, hold->ai_addr, hold->ai_addrlen);
 341                 addr_set_port(&host->addr, 0);
 342                 host->retries = 0;
 343         }
 344
 345         dest = host->addr;
 346         if (addr_get_port(&dest) == 0) {
 347                 /* Build a PMAP packet */
 348                 nsm_log(LOG_DEBUG, "Sending portmap query to %s", host->name);
 349
 350                 addr_set_port(&dest, 111);
 351                 *p++ = htonl(100000);
 352                 *p++ = htonl(2);
 353                 *p++ = htonl(3);
 354
 355                 /* Auth and verf */
 356                 *p++ = 0; *p++ = 0;
 357                 *p++ = 0; *p++ = 0;
 358
 359                 *p++ = htonl(NSM_PROGRAM);
 360                 *p++ = htonl(NSM_VERSION);
 361                 *p++ = htonl(IPPROTO_UDP);
 362                 *p++ = 0;
 363         } else {
 364                 /* Build an SM_NOTIFY packet */
 365                 nsm_log(LOG_DEBUG, "Sending SM_NOTIFY to %s", host->name);
 366
 367                 *p++ = htonl(NSM_PROGRAM);
 368                 *p++ = htonl(NSM_VERSION);
 369                 *p++ = htonl(NSM_NOTIFY);
 370
 371                 /* Auth and verf */
 372                 *p++ = 0; *p++ = 0;
 373                 *p++ = 0; *p++ = 0;
 374
 375                 /* state change */
 376                 len = strlen(nsm_hostname);
 377                 *p++ = htonl(len);
 378                 memcpy(p, nsm_hostname, len);
 379                 p += (len + 3) >> 2;
 380                 *p++ = htonl(nsm_state);
 381         }
 382         len = (p - msgbuf) << 2;
 383
 384         sendto(sock, msgbuf, len, 0, (struct sockaddr *) &dest, sizeof(dest));
 385 }
 386
 387 /*
 388  * Receive reply from remote host
 389  */
 390 void
 391 recv_reply(int sock)
 392 {
 393         struct nsm_host *hp;
 394         uint32_t        msgbuf[MAXMSGSIZE], *p, *end;
 395         uint32_t        xid;
 396         int             res;
 397
 398         res = recv(sock, msgbuf, sizeof(msgbuf), 0);
 399         if (res < 0)
 400                 return;
 401
 402         nsm_log(LOG_DEBUG, "Received packet...");
 403
 404         p = msgbuf;
 405         end = p + (res >> 2);
 406
 407         xid = ntohl(*p++);
 408         if (*p++ != htonl(1)    /* must be REPLY */
 409          || *p++ != htonl(0)    /* must be ACCEPTED */
 410          || *p++ != htonl(0)    /* must be NULL verifier */
 411          || *p++ != htonl(0)
 412          || *p++ != htonl(0))   /* must be SUCCESS */
 413                 return;
 414
 415         /* Before we look at the data, find the host struct for
 416            this reply */
 417         if ((hp = find_host(xid)) == NULL)
 418                 return;
 419
 420         if (addr_get_port(&hp->addr) == 0) {
 421                 /* This was a portmap request */
 422                 unsigned int    port;
 423
 424                 port = ntohl(*p++);
 425                 if (p > end)
 426                         goto fail;
 427
 428                 hp->send_next = time(NULL);
 429                 if (port == 0) {
 430                         /* No binding for statd. Delay the next
 431                          * portmap query for max timeout */
 432                         nsm_log(LOG_DEBUG, "No statd on %s", hp->name);
 433                         hp->timeout = NSM_MAX_TIMEOUT;
 434                         hp->send_next += NSM_MAX_TIMEOUT;
 435                 } else {
 436                         addr_set_port(&hp->addr, port);
 437                         if (hp->timeout >= NSM_MAX_TIMEOUT / 4)
 438                                 hp->timeout = NSM_MAX_TIMEOUT / 4;
 439                 }
 440                 hp->xid = 0;
 441         } else {
 442                 /* Successful NOTIFY call. Server returns void,
 443                  * so nothing we need to do here (except
 444                  * check that we didn't read past the end of the
 445                  * packet)
 446                  */
 447                 if (p <= end) {
 448                         nsm_log(LOG_DEBUG, "Host %s notified successfully", hp->name);
 449                         unlink(hp->path);
 450                         free(hp->name);
 451                         free(hp->path);
 452                         free(hp);
 453                         freeaddrinfo(hp->ai);
 454                         return;
 455                 }
 456         }
 457
 458 fail:   /* Re-insert the host */
 459         insert_host(hp);
 460 }
 461
 462 /*
 463  * Back up all hosts from the sm directory to sm.bak
 464  */
 465 static void
 466 backup_hosts(const char *dirname, const char *bakname)
 467 {
 468         struct dirent   *de;
 469         DIR             *dir;
 470
 471         if (!(dir = opendir(dirname))) {
 472                 perror(dirname);
 473                 return;
 474         }
 475
 476         while ((de = readdir(dir)) != NULL) {
 477                 char    src[1024], dst[1024];
 478
 479                 if (de->d_name[0] == '.')
 480                         continue;
 481
 482                 snprintf(src, sizeof(src), "%s/%s", dirname, de->d_name);
 483                 snprintf(dst, sizeof(dst), "%s/%s", bakname, de->d_name);
 484                 if (rename(src, dst) < 0) {
 485                         nsm_log(LOG_WARNING,
 486                                 "Failed to rename %s -> %s: %m",
 487                                 src, dst);
 488                 }
 489         }
 490         closedir(dir);
 491 }
 492
 493 /*
 494  * Get all entries from sm.bak and convert them to host names
 495  */
 496 static void
 497 get_hosts(const char *dirname)
 498 {
 499         struct nsm_host *host;
 500         struct dirent   *de;
 501         DIR             *dir;
 502
 503         if (!(dir = opendir(dirname))) {
 504                 perror(dirname);
 505                 return;
 506         }
 507
 508         host = NULL;
 509         while ((de = readdir(dir)) != NULL) {
 510                 struct stat     stb;
 511                 char            path[1024];
 512
 513                 if (de->d_name[0] == '.')
 514                         continue;
 515                 if (host == NULL)
 516                         host = calloc(1, sizeof(*host));
 517
 518                 snprintf(path, sizeof(path), "%s/%s", dirname, de->d_name);
 519                 if (stat(path, &stb) < 0)
 520                         continue;
 521
 522                 host->ai = host_lookup(AF_UNSPEC, de->d_name);
 523                 if (! host->ai) {
 524                         nsm_log(LOG_WARNING,
 525                                 "%s doesn't seem to be a valid address, skipped",
 526                                 de->d_name);
 527                         unlink(path);
 528                         continue;
 529                 }
 530
 531                 host->last_used = stb.st_mtime;
 532                 host->timeout = NSM_TIMEOUT;
 533                 host->path = strdup(path);
 534                 host->name = strdup(de->d_name);
 535                 host->retries = 100; /* force address retry */
 536
 537                 insert_host(host);
 538                 host = NULL;
 539         }
 540         closedir(dir);
 541
 542         if (host)
 543                 free(host);
 544 }
 545
 546 /*
 547  * Insert host into sorted list
 548  */
 549 void
 550 insert_host(struct nsm_host *host)
 551 {
 552         struct nsm_host **where, *p;
 553
 554         where = &hosts;
 555         while ((p = *where) != 0) {
 556                 /* Sort in ascending order of timeout */
 557                 if (host->send_next < p->send_next)
 558                         break;
 559                 /* If we have the same timeout, put the
 560                  * most recently used host first.
 561                  * This makes sure that "recent" hosts
 562                  * get notified first.
 563                  */
 564                 if (host->send_next == p->send_next
 565                  && host->last_used > p->last_used)
 566                         break;
 567                 where = &p->next;
 568         }
 569
 570         host->next = *where;
 571         *where = host;
 572 }
 573
 574 /*
 575  * Find host given the XID
 576  */
 577 struct nsm_host *
 578 find_host(uint32_t xid)
 579 {
 580         struct nsm_host **where, *p;
 581
 582         where = &hosts;
 583         while ((p = *where) != 0) {
 584                 if (p->xid == xid) {
 585                         *where = p->next;
 586                         return p;
 587                 }
 588                 where = &p->next;
 589         }
 590         return NULL;
 591 }
 592
 593
 594 /*
 595  * Retrieve the current NSM state
 596  */
 597 unsigned int
 598 nsm_get_state(int update)
 599 {
 600         char            newfile[PATH_MAX];
 601         int             fd, state;
 602
 603         if ((fd = open(_SM_STATE_PATH, O_RDONLY)) < 0) {
 604                 if (!opt_quiet) {
 605                         nsm_log(LOG_WARNING, "%s: %m", _SM_STATE_PATH);
 606                         nsm_log(LOG_WARNING, "Creating %s, set initial state 1",
 607                                 _SM_STATE_PATH);
 608                 }
 609                 state = 1;
 610                 update = 1;
 611         } else {
 612                 if (read(fd, &state, sizeof(state)) != sizeof(state)) {
 613                         nsm_log(LOG_WARNING,
 614                                 "%s: bad file size, setting state = 1",
 615                                 _SM_STATE_PATH);
 616                         state = 1;
 617                         update = 1;
 618                 } else {
 619                         if (!(state & 1))
 620                                 state += 1;
 621                 }
 622                 close(fd);
 623         }
 624
 625         if (update) {
 626                 state += 2;
 627                 snprintf(newfile, sizeof(newfile),
 628                                 "%s.new", _SM_STATE_PATH);
 629                 if ((fd = open(newfile, O_CREAT|O_WRONLY, 0644)) < 0) {
 630                         nsm_log(LOG_WARNING, "Cannot create %s: %m", newfile);
 631                         exit(1);
 632                 }
 633                 if (write(fd, &state, sizeof(state)) != sizeof(state)) {
 634                         nsm_log(LOG_WARNING,
 635                                 "Failed to write state to %s", newfile);
 636                         exit(1);
 637                 }
 638                 close(fd);
 639                 if (rename(newfile, _SM_STATE_PATH) < 0) {
 640                         nsm_log(LOG_WARNING,
 641                                 "Cannot create %s: %m", _SM_STATE_PATH);
 642                         exit(1);
 643                 }
 644                 sync();
 645         }
 646
 647         return state;
 648 }
 649
 650 /*
 651  * Address handling utilities
 652  */
 653
 654 int
 655 addr_get_port(nsm_address *addr)
 656 {
 657         switch (((struct sockaddr *) addr)->sa_family) {
 658         case AF_INET:
 659                 return ntohs(((struct sockaddr_in *) addr)->sin_port);
 660         case AF_INET6:
 661                 return ntohs(((struct sockaddr_in6 *) addr)->sin6_port);
 662         }
 663         return 0;
 664 }
 665
 666 static void
 667 addr_set_port(nsm_address *addr, int port)
 668 {
 669         switch (((struct sockaddr *) addr)->sa_family) {
 670         case AF_INET:
 671                 ((struct sockaddr_in *) addr)->sin_port = htons(port);
 672                 break;
 673         case AF_INET6:
 674                 ((struct sockaddr_in6 *) addr)->sin6_port = htons(port);
 675         }
 676 }
 677
 678 static struct addrinfo *
 679 host_lookup(int af, const char *name)
 680 {
 681         struct addrinfo hints, *ai;
 682
 683         memset(&hints, 0, sizeof(hints));
 684         hints.ai_family = af;
 685         hints.ai_protocol = IPPROTO_UDP;
 686
 687         if (getaddrinfo(name, NULL, &hints, &ai) != 0)
 688                 return NULL;
 689
 690         return ai;
 691 }
 692
 693 /*
 694  * Log a message
 695  */
 696 void
 697 nsm_log(int fac, const char *fmt, ...)
 698 {
 699         va_list ap;
 700
 701         if (fac == LOG_DEBUG && !opt_debug)
 702                 return;
 703
 704         va_start(ap, fmt);
 705         if (log_syslog)
 706                 vsyslog(fac, fmt, ap);
 707         else {
 708                 vfprintf(stderr, fmt, ap);
 709                 fputs("\n", stderr);
 710         }
 711         va_end(ap);
 712 }
 713
 714 /*
 715  * Record pid in /var/run/sm-notify.pid
 716  * This file should remain until a reboot, even if the
 717  * program exits.
 718  * If file already exists, fail.
 719  */
 720 static int record_pid()
 721 {
 722         char pid[20];
 723         int fd;
 724
 725         snprintf(pid, 20, "%d\n", getpid());
 726         fd = open("/var/run/sm-notify.pid", O_CREAT|O_EXCL|O_WRONLY, 0600);
 727         if (fd < 0)
 728                 return 0;
 729         write(fd, pid, strlen(pid));
 730         close(fd);
 731         return 1;
 732 }
 733
 734 /* Drop privileges to match owner of state-directory
 735  * (in case a reply triggers some unknown bug).
 736  */
 737 static void drop_privs(void)
 738 {
 739         struct stat st;
 740
 741         if (stat(_SM_DIR_PATH, &st) == -1 &&
 742             stat(_SM_BASE_PATH, &st) == -1) {
 743                 st.st_uid = 0;
 744                 st.st_gid = 0;
 745         }
 746
 747         if (st.st_uid == 0) {
 748                 nsm_log(LOG_WARNING,
 749                         "sm-notify running as root. chown %s to choose different user\n",
 750                     _SM_DIR_PATH);
 751                 return;
 752         }
 753
 754         setgroups(0, NULL);
 755         if (setgid(st.st_gid) == -1
 756             || setuid(st.st_uid) == -1) {
 757                 nsm_log(LOG_ERR, "Fail to drop privileges");
 758                 exit(1);
 759         }
 760 }