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 #ifdef HAVE_CONFIG_H
   8 #include <config.h>
   9 #endif
  10
  11 #include <sys/types.h>
  12 #include <sys/socket.h>
  13 #include <sys/stat.h>
  14 #include <sys/poll.h>
  15 #include <sys/param.h>
  16 #include <sys/syslog.h>
  17 #include <arpa/inet.h>
  18 #include <dirent.h>
  19 #include <time.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <stdlib.h>
  23 #include <fcntl.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26 #include <stdarg.h>
  27 #include <netdb.h>
  28 #include <errno.h>
  29 #include <grp.h>
  30
  31 #include "xlog.h"
  32 #include "nfsrpc.h"
  33
  34 #ifndef BASEDIR
  35 # ifdef NFS_STATEDIR
  36 #  define BASEDIR               NFS_STATEDIR
  37 # else
  38 #  define BASEDIR               "/var/lib/nfs"
  39 # endif
  40 #endif
  41
  42 #define DEFAULT_SM_STATE_PATH   BASEDIR "/state"
  43 #define DEFAULT_SM_DIR_PATH     BASEDIR "/sm"
  44 #define DEFAULT_SM_BAK_PATH     DEFAULT_SM_DIR_PATH ".bak"
  45
  46 char *_SM_BASE_PATH = BASEDIR;
  47 char *_SM_STATE_PATH = DEFAULT_SM_STATE_PATH;
  48 char *_SM_DIR_PATH = DEFAULT_SM_DIR_PATH;
  49 char *_SM_BAK_PATH = DEFAULT_SM_BAK_PATH;
  50
  51 #define NSM_PROG        100024
  52 #define NSM_PROGRAM     100024
  53 #define NSM_VERSION     1
  54 #define NSM_TIMEOUT     2
  55 #define NSM_NOTIFY      6
  56 #define NSM_MAX_TIMEOUT 120     /* don't make this too big */
  57 #define MAXMSGSIZE      256
  58
  59 struct nsm_host {
  60         struct nsm_host *       next;
  61         char *                  name;
  62         char *                  path;
  63         struct sockaddr_storage addr;
  64         struct addrinfo         *ai;
  65         time_t                  last_used;
  66         time_t                  send_next;
  67         unsigned int            timeout;
  68         unsigned int            retries;
  69         unsigned int            xid;
  70 };
  71
  72 static char             nsm_hostname[256];
  73 static uint32_t         nsm_state;
  74 static int              opt_debug = 0;
  75 static int              opt_update_state = 1;
  76 static unsigned int     opt_max_retry = 15 * 60;
  77 static char *           opt_srcaddr = 0;
  78 static uint16_t         opt_srcport = 0;
  79
  80 static unsigned int     nsm_get_state(int);
  81 static void             notify(void);
  82 static int              notify_host(int, struct nsm_host *);
  83 static void             recv_reply(int);
  84 static void             backup_hosts(const char *, const char *);
  85 static void             get_hosts(const char *);
  86 static void             insert_host(struct nsm_host *);
  87 static struct nsm_host *find_host(uint32_t);
  88 static int              record_pid(void);
  89 static void             drop_privs(void);
  90 static void             set_kernel_nsm_state(int state);
  91
  92 static struct nsm_host *        hosts = NULL;
  93
  94 static struct addrinfo *smn_lookup(const char *name)
  95 {
  96         struct addrinfo *ai, hint = {
  97 #if HAVE_DECL_AI_ADDRCONFIG
  98                 .ai_flags       = AI_ADDRCONFIG,
  99 #endif  /* HAVE_DECL_AI_ADDRCONFIG */
 100                 .ai_family      = AF_INET,
 101                 .ai_protocol    = IPPROTO_UDP,
 102         };
 103         int error;
 104
 105         error = getaddrinfo(name, NULL, &hint, &ai);
 106         if (error) {
 107                 xlog(D_GENERAL, "getaddrinfo(3): %s", gai_strerror(error));
 108                 return NULL;
 109         }
 110
 111         return ai;
 112 }
 113
 114 static void smn_forget_host(struct nsm_host *host)
 115 {
 116         unlink(host->path);
 117         free(host->path);
 118         free(host->name);
 119         if (host->ai)
 120                 freeaddrinfo(host->ai);
 121
 122         free(host);
 123 }
 124
 125 int
 126 main(int argc, char **argv)
 127 {
 128         int     c;
 129         int     force = 0;
 130         char *  progname;
 131
 132         progname = strrchr(argv[0], '/');
 133         if (progname != NULL)
 134                 progname++;
 135         else
 136                 progname = argv[0];
 137
 138         while ((c = getopt(argc, argv, "dm:np:v:P:f")) != -1) {
 139                 switch (c) {
 140                 case 'f':
 141                         force = 1;
 142                         break;
 143                 case 'd':
 144                         opt_debug++;
 145                         break;
 146                 case 'm':
 147                         opt_max_retry = atoi(optarg) * 60;
 148                         break;
 149                 case 'n':
 150                         opt_update_state = 0;
 151                         break;
 152                 case 'p':
 153                         opt_srcport = atoi(optarg);
 154                         break;
 155                 case 'v':
 156                         opt_srcaddr = optarg;
 157                         break;
 158                 case 'P':
 159                         _SM_BASE_PATH = strdup(optarg);
 160                         _SM_STATE_PATH = malloc(strlen(optarg)+1+sizeof("state"));
 161                         _SM_DIR_PATH = malloc(strlen(optarg)+1+sizeof("sm"));
 162                         _SM_BAK_PATH = malloc(strlen(optarg)+1+sizeof("sm.bak"));
 163                         if (_SM_BASE_PATH == NULL ||
 164                             _SM_STATE_PATH == NULL ||
 165                             _SM_DIR_PATH == NULL ||
 166                             _SM_BAK_PATH == NULL) {
 167                                 fprintf(stderr, "unable to allocate memory");
 168                                 exit(1);
 169                         }
 170                         strcat(strcpy(_SM_STATE_PATH, _SM_BASE_PATH), "/state");
 171                         strcat(strcpy(_SM_DIR_PATH, _SM_BASE_PATH), "/sm");
 172                         strcat(strcpy(_SM_BAK_PATH, _SM_BASE_PATH), "/sm.bak");
 173                         break;
 174
 175                 default:
 176                         goto usage;
 177                 }
 178         }
 179
 180         if (optind < argc) {
 181 usage:          fprintf(stderr,
 182                         "Usage: %s -notify [-dfq] [-m max-retry-minutes] [-p srcport]\n"
 183                         "            [-P /path/to/state/directory] [-v my_host_name]\n",
 184                         progname);
 185                 exit(1);
 186         }
 187
 188         xlog_syslog(1);
 189         if (opt_debug) {
 190                 xlog_stderr(1);
 191                 xlog_config(D_ALL, 1);
 192         } else
 193                 xlog_stderr(0);
 194
 195         xlog_open(progname);
 196         xlog(L_NOTICE, "Version " VERSION " starting");
 197
 198         if (strcmp(_SM_BASE_PATH, BASEDIR) == 0) {
 199                 if (record_pid() == 0 && force == 0 && opt_update_state == 1) {
 200                         /* already run, don't try again */
 201                         xlog(L_NOTICE, "Already notifying clients; Exiting!");
 202                         exit(0);
 203                 }
 204         }
 205
 206         if (opt_srcaddr) {
 207                 strncpy(nsm_hostname, opt_srcaddr, sizeof(nsm_hostname)-1);
 208         } else
 209         if (gethostname(nsm_hostname, sizeof(nsm_hostname)) < 0) {
 210                 xlog(L_ERROR, "Failed to obtain name of local host: %m");
 211                 exit(1);
 212         }
 213
 214         backup_hosts(_SM_DIR_PATH, _SM_BAK_PATH);
 215         get_hosts(_SM_BAK_PATH);
 216
 217         /* If there are not hosts to notify, just exit */
 218         if (!hosts) {
 219                 xlog(D_GENERAL, "No hosts to notify; exiting");
 220                 return 0;
 221         }
 222
 223         /* Get and update the NSM state. This will call sync() */
 224         nsm_state = nsm_get_state(opt_update_state);
 225         set_kernel_nsm_state(nsm_state);
 226
 227         if (!opt_debug) {
 228                 xlog(L_NOTICE, "Backgrounding to notify hosts...\n");
 229
 230                 if (daemon(0, 0) < 0) {
 231                         xlog(L_ERROR, "unable to background: %m");
 232                         exit(1);
 233                 }
 234
 235                 close(0);
 236                 close(1);
 237                 close(2);
 238         }
 239
 240         notify();
 241
 242         if (hosts) {
 243                 struct nsm_host *hp;
 244
 245                 while ((hp = hosts) != 0) {
 246                         hosts = hp->next;
 247                         xlog(L_NOTICE, "Unable to notify %s, giving up",
 248                                 hp->name);
 249                 }
 250                 exit(1);
 251         }
 252
 253         exit(0);
 254 }
 255
 256 /*
 257  * Notify hosts
 258  */
 259 static void
 260 notify(void)
 261 {
 262         struct sockaddr_storage address;
 263         struct sockaddr *local_addr = (struct sockaddr *)&address;
 264         time_t  failtime = 0;
 265         int     sock = -1;
 266         int retry_cnt = 0;
 267
 268  retry:
 269         sock = socket(AF_INET, SOCK_DGRAM, 0);
 270         if (sock < 0) {
 271                 xlog(L_ERROR, "Failed to create RPC socket: %m");
 272                 exit(1);
 273         }
 274         fcntl(sock, F_SETFL, O_NONBLOCK);
 275
 276         memset(&address, 0, sizeof(address));
 277         local_addr->sa_family = AF_INET;        /* Default to IPv4 */
 278
 279         /* Bind source IP if provided on command line */
 280         if (opt_srcaddr) {
 281                 struct addrinfo *ai = smn_lookup(opt_srcaddr);
 282                 if (!ai) {
 283                         xlog(L_ERROR,
 284                                 "Not a valid hostname or address: \"%s\"",
 285                                 opt_srcaddr);
 286                         exit(1);
 287                 }
 288
 289                 /* We know it's IPv4 at this point */
 290                 memcpy(local_addr, ai->ai_addr, ai->ai_addrlen);
 291
 292                 freeaddrinfo(ai);
 293         }
 294
 295         /* Use source port if provided on the command line,
 296          * otherwise use bindresvport */
 297         if (opt_srcport) {
 298                 nfs_set_port(local_addr, opt_srcport);
 299                 if (bind(sock, local_addr, sizeof(struct sockaddr_in)) < 0) {
 300                         xlog(L_ERROR, "Failed to bind RPC socket: %m");
 301                         exit(1);
 302                 }
 303         } else {
 304                 struct servent *se;
 305                 struct sockaddr_in *sin = (struct sockaddr_in *)local_addr;
 306                 (void) bindresvport(sock, sin);
 307                 /* try to avoid known ports */
 308                 se = getservbyport(sin->sin_port, "udp");
 309                 if (se && retry_cnt < 100) {
 310                         retry_cnt++;
 311                         close(sock);
 312                         goto retry;
 313                 }
 314         }
 315
 316         if (opt_max_retry)
 317                 failtime = time(NULL) + opt_max_retry;
 318
 319         drop_privs();
 320
 321         while (hosts) {
 322                 struct pollfd   pfd;
 323                 time_t          now = time(NULL);
 324                 unsigned int    sent = 0;
 325                 struct nsm_host *hp;
 326                 long            wait;
 327
 328                 if (failtime && now >= failtime)
 329                         break;
 330
 331                 while (hosts && ((wait = hosts->send_next - now) <= 0)) {
 332                         /* Never send more than 10 packets at once */
 333                         if (sent++ >= 10)
 334                                 break;
 335
 336                         /* Remove queue head */
 337                         hp = hosts;
 338                         hosts = hp->next;
 339
 340                         if (notify_host(sock, hp))
 341                                 continue;
 342
 343                         /* Set the timeout for this call, using an
 344                            exponential timeout strategy */
 345                         wait = hp->timeout;
 346                         if ((hp->timeout <<= 1) > NSM_MAX_TIMEOUT)
 347                                 hp->timeout = NSM_MAX_TIMEOUT;
 348                         hp->send_next = now + wait;
 349                         hp->retries++;
 350
 351                         insert_host(hp);
 352                 }
 353                 if (hosts == NULL)
 354                         return;
 355
 356                 xlog(D_GENERAL, "Host %s due in %ld seconds",
 357                                 hosts->name, wait);
 358
 359                 pfd.fd = sock;
 360                 pfd.events = POLLIN;
 361
 362                 wait *= 1000;
 363                 if (wait < 100)
 364                         wait = 100;
 365                 if (poll(&pfd, 1, wait) != 1)
 366                         continue;
 367
 368                 recv_reply(sock);
 369         }
 370 }
 371
 372 /*
 373  * Send notification to a single host
 374  */
 375 static int
 376 notify_host(int sock, struct nsm_host *host)
 377 {
 378         struct sockaddr_storage address;
 379         struct sockaddr *dest = (struct sockaddr *)&address;
 380         socklen_t destlen = sizeof(address);
 381         static unsigned int     xid = 0;
 382         uint32_t                msgbuf[MAXMSGSIZE], *p;
 383         unsigned int            len;
 384
 385         if (!xid)
 386                 xid = getpid() + time(NULL);
 387         if (!host->xid)
 388                 host->xid = xid++;
 389
 390         if (host->ai == NULL) {
 391                 host->ai = smn_lookup(host->name);
 392                 if (host->ai == NULL) {
 393                         xlog_warn("DNS resolution of %s failed; "
 394                                 "retrying later", host->name);
 395                         return 0;
 396                 }
 397         }
 398
 399         memset(msgbuf, 0, sizeof(msgbuf));
 400         p = msgbuf;
 401         *p++ = htonl(host->xid);
 402         *p++ = 0;
 403         *p++ = htonl(2);
 404
 405         /* If we retransmitted 4 times, reset the port to force
 406          * a new portmap lookup (in case statd was restarted).
 407          * We also rotate through multiple IP addresses at this
 408          * point.
 409          */
 410         if (host->retries >= 4) {
 411                 /* don't rotate if there is only one addrinfo */
 412                 if (host->ai->ai_next == NULL)
 413                         memcpy(&host->addr, host->ai->ai_addr,
 414                                                 host->ai->ai_addrlen);
 415                 else {
 416                         struct addrinfo *first = host->ai;
 417                         struct addrinfo **next = &host->ai;
 418
 419                         /* remove the first entry from the list */
 420                         host->ai = first->ai_next;
 421                         first->ai_next = NULL;
 422                         /* find the end of the list */
 423                         next = &first->ai_next;
 424                         while ( *next )
 425                                 next = & (*next)->ai_next;
 426                         /* put first entry at end */
 427                         *next = first;
 428                         memcpy(&host->addr, first->ai_addr,
 429                                                 first->ai_addrlen);
 430                 }
 431
 432                 nfs_set_port((struct sockaddr *)&host->addr, 0);
 433                 host->retries = 0;
 434         }
 435
 436         memcpy(dest, &host->addr, destlen);
 437         if (nfs_get_port(dest) == 0) {
 438                 /* Build a PMAP packet */
 439                 xlog(D_GENERAL, "Sending portmap query to %s", host->name);
 440
 441                 nfs_set_port(dest, 111);
 442                 *p++ = htonl(100000);
 443                 *p++ = htonl(2);
 444                 *p++ = htonl(3);
 445
 446                 /* Auth and verf */
 447                 *p++ = 0; *p++ = 0;
 448                 *p++ = 0; *p++ = 0;
 449
 450                 *p++ = htonl(NSM_PROGRAM);
 451                 *p++ = htonl(NSM_VERSION);
 452                 *p++ = htonl(IPPROTO_UDP);
 453                 *p++ = 0;
 454         } else {
 455                 /* Build an SM_NOTIFY packet */
 456                 xlog(D_GENERAL, "Sending SM_NOTIFY to %s", host->name);
 457
 458                 *p++ = htonl(NSM_PROGRAM);
 459                 *p++ = htonl(NSM_VERSION);
 460                 *p++ = htonl(NSM_NOTIFY);
 461
 462                 /* Auth and verf */
 463                 *p++ = 0; *p++ = 0;
 464                 *p++ = 0; *p++ = 0;
 465
 466                 /* state change */
 467                 len = strlen(nsm_hostname);
 468                 *p++ = htonl(len);
 469                 memcpy(p, nsm_hostname, len);
 470                 p += (len + 3) >> 2;
 471                 *p++ = htonl(nsm_state);
 472         }
 473         len = (p - msgbuf) << 2;
 474
 475         if (sendto(sock, msgbuf, len, 0, dest, destlen) < 0)
 476                 xlog_warn("Sending Reboot Notification to "
 477                         "'%s' failed: errno %d (%m)", host->name, errno);
 478
 479         return 0;
 480 }
 481
 482 /*
 483  * Receive reply from remote host
 484  */
 485 static void
 486 recv_reply(int sock)
 487 {
 488         struct nsm_host *hp;
 489         struct sockaddr *sap;
 490         uint32_t        msgbuf[MAXMSGSIZE], *p, *end;
 491         uint32_t        xid;
 492         int             res;
 493
 494         res = recv(sock, msgbuf, sizeof(msgbuf), 0);
 495         if (res < 0)
 496                 return;
 497
 498         xlog(D_GENERAL, "Received packet...");
 499
 500         p = msgbuf;
 501         end = p + (res >> 2);
 502
 503         xid = ntohl(*p++);
 504         if (*p++ != htonl(1)    /* must be REPLY */
 505          || *p++ != htonl(0)    /* must be ACCEPTED */
 506          || *p++ != htonl(0)    /* must be NULL verifier */
 507          || *p++ != htonl(0)
 508          || *p++ != htonl(0))   /* must be SUCCESS */
 509                 return;
 510
 511         /* Before we look at the data, find the host struct for
 512            this reply */
 513         if ((hp = find_host(xid)) == NULL)
 514                 return;
 515         sap = (struct sockaddr *)&hp->addr;
 516
 517         if (nfs_get_port(sap) == 0) {
 518                 /* This was a portmap request */
 519                 unsigned int    port;
 520
 521                 port = ntohl(*p++);
 522                 if (p > end)
 523                         goto fail;
 524
 525                 hp->send_next = time(NULL);
 526                 if (port == 0) {
 527                         /* No binding for statd. Delay the next
 528                          * portmap query for max timeout */
 529                         xlog(D_GENERAL, "No statd on %s", hp->name);
 530                         hp->timeout = NSM_MAX_TIMEOUT;
 531                         hp->send_next += NSM_MAX_TIMEOUT;
 532                 } else {
 533                         nfs_set_port(sap, port);
 534                         if (hp->timeout >= NSM_MAX_TIMEOUT / 4)
 535                                 hp->timeout = NSM_MAX_TIMEOUT / 4;
 536                 }
 537                 hp->xid = 0;
 538         } else {
 539                 /* Successful NOTIFY call. Server returns void,
 540                  * so nothing we need to do here (except
 541                  * check that we didn't read past the end of the
 542                  * packet)
 543                  */
 544                 if (p <= end) {
 545                         xlog(D_GENERAL, "Host %s notified successfully",
 546                                         hp->name);
 547                         smn_forget_host(hp);
 548                         return;
 549                 }
 550         }
 551
 552 fail:   /* Re-insert the host */
 553         insert_host(hp);
 554 }
 555
 556 /*
 557  * Back up all hosts from the sm directory to sm.bak
 558  */
 559 static void
 560 backup_hosts(const char *dirname, const char *bakname)
 561 {
 562         struct dirent   *de;
 563         DIR             *dir;
 564
 565         if (!(dir = opendir(dirname))) {
 566                 xlog_warn("Failed to open %s: %m", dirname);
 567                 return;
 568         }
 569
 570         while ((de = readdir(dir)) != NULL) {
 571                 char    src[1024], dst[1024];
 572
 573                 if (de->d_name[0] == '.')
 574                         continue;
 575
 576                 snprintf(src, sizeof(src), "%s/%s", dirname, de->d_name);
 577                 snprintf(dst, sizeof(dst), "%s/%s", bakname, de->d_name);
 578                 if (rename(src, dst) < 0)
 579                         xlog_warn("Failed to rename %s -> %s: %m", src, dst);
 580         }
 581         closedir(dir);
 582 }
 583
 584 /*
 585  * Get all entries from sm.bak and convert them to host entries
 586  */
 587 static void
 588 get_hosts(const char *dirname)
 589 {
 590         struct nsm_host *host;
 591         struct dirent   *de;
 592         DIR             *dir;
 593
 594         if (!(dir = opendir(dirname))) {
 595                 xlog_warn("Failed to open %s: %m", dirname);
 596                 return;
 597         }
 598
 599         host = NULL;
 600         while ((de = readdir(dir)) != NULL) {
 601                 struct stat     stb;
 602                 char            path[1024];
 603
 604                 if (de->d_name[0] == '.')
 605                         continue;
 606                 if (host == NULL)
 607                         host = calloc(1, sizeof(*host));
 608                 if (host == NULL) {
 609                         xlog_warn("Unable to allocate memory");
 610                         return;
 611                 }
 612
 613                 snprintf(path, sizeof(path), "%s/%s", dirname, de->d_name);
 614                 if (stat(path, &stb) < 0)
 615                         continue;
 616
 617                 host->last_used = stb.st_mtime;
 618                 host->timeout = NSM_TIMEOUT;
 619                 host->path = strdup(path);
 620                 host->name = strdup(de->d_name);
 621                 host->retries = 100; /* force address retry */
 622
 623                 insert_host(host);
 624                 host = NULL;
 625         }
 626         closedir(dir);
 627
 628         if (host)
 629                 free(host);
 630 }
 631
 632 /*
 633  * Insert host into sorted list
 634  */
 635 static void
 636 insert_host(struct nsm_host *host)
 637 {
 638         struct nsm_host **where, *p;
 639
 640         where = &hosts;
 641         while ((p = *where) != 0) {
 642                 /* Sort in ascending order of timeout */
 643                 if (host->send_next < p->send_next)
 644                         break;
 645                 /* If we have the same timeout, put the
 646                  * most recently used host first.
 647                  * This makes sure that "recent" hosts
 648                  * get notified first.
 649                  */
 650                 if (host->send_next == p->send_next
 651                  && host->last_used > p->last_used)
 652                         break;
 653                 where = &p->next;
 654         }
 655
 656         host->next = *where;
 657         *where = host;
 658 }
 659
 660 /*
 661  * Find host given the XID
 662  */
 663 static struct nsm_host *
 664 find_host(uint32_t xid)
 665 {
 666         struct nsm_host **where, *p;
 667
 668         where = &hosts;
 669         while ((p = *where) != 0) {
 670                 if (p->xid == xid) {
 671                         *where = p->next;
 672                         return p;
 673                 }
 674                 where = &p->next;
 675         }
 676         return NULL;
 677 }
 678
 679
 680 /*
 681  * Retrieve the current NSM state
 682  */
 683 static unsigned int
 684 nsm_get_state(int update)
 685 {
 686         char            newfile[PATH_MAX];
 687         int             fd, state;
 688
 689         if ((fd = open(_SM_STATE_PATH, O_RDONLY)) < 0) {
 690                 xlog_warn("%s: %m", _SM_STATE_PATH);
 691                 xlog_warn("Creating %s, set initial state 1",
 692                         _SM_STATE_PATH);
 693                 state = 1;
 694                 update = 1;
 695         } else {
 696                 if (read(fd, &state, sizeof(state)) != sizeof(state)) {
 697                         xlog_warn("%s: bad file size, setting state = 1",
 698                                 _SM_STATE_PATH);
 699                         state = 1;
 700                         update = 1;
 701                 } else {
 702                         if (!(state & 1))
 703                                 state += 1;
 704                 }
 705                 close(fd);
 706         }
 707
 708         if (update) {
 709                 state += 2;
 710                 snprintf(newfile, sizeof(newfile),
 711                                 "%s.new", _SM_STATE_PATH);
 712                 if ((fd = open(newfile, O_CREAT|O_WRONLY, 0644)) < 0) {
 713                         xlog(L_ERROR, "Cannot create %s: %m", newfile);
 714                         exit(1);
 715                 }
 716                 if (write(fd, &state, sizeof(state)) != sizeof(state)) {
 717                         xlog(L_ERROR,
 718                                 "Failed to write state to %s", newfile);
 719                         exit(1);
 720                 }
 721                 close(fd);
 722                 if (rename(newfile, _SM_STATE_PATH) < 0) {
 723                         xlog(L_ERROR,
 724                                 "Cannot create %s: %m", _SM_STATE_PATH);
 725                         exit(1);
 726                 }
 727                 sync();
 728         }
 729
 730         return state;
 731 }
 732
 733 /*
 734  * Record pid in /var/run/sm-notify.pid
 735  * This file should remain until a reboot, even if the
 736  * program exits.
 737  * If file already exists, fail.
 738  */
 739 static int record_pid(void)
 740 {
 741         char pid[20];
 742         ssize_t len;
 743         int fd;
 744
 745         (void)snprintf(pid, sizeof(pid), "%d\n", (int)getpid());
 746         fd = open("/var/run/sm-notify.pid", O_CREAT|O_EXCL|O_WRONLY, 0600);
 747         if (fd < 0)
 748                 return 0;
 749
 750         len = write(fd, pid, strlen(pid));
 751         if ((len < 0) || ((size_t)len != strlen(pid))) {
 752                 xlog_warn("Writing to pid file failed: errno %d (%m)",
 753                                 errno);
 754         }
 755
 756         (void)close(fd);
 757         return 1;
 758 }
 759
 760 /* Drop privileges to match owner of state-directory
 761  * (in case a reply triggers some unknown bug).
 762  */
 763 static void drop_privs(void)
 764 {
 765         struct stat st;
 766
 767         if (stat(_SM_DIR_PATH, &st) == -1 &&
 768             stat(_SM_BASE_PATH, &st) == -1) {
 769                 st.st_uid = 0;
 770                 st.st_gid = 0;
 771         }
 772
 773         if (st.st_uid == 0) {
 774                 xlog_warn("Running as 'root'.  "
 775                         "chown %s to choose different user", _SM_DIR_PATH);
 776                 return;
 777         }
 778
 779         setgroups(0, NULL);
 780         if (setgid(st.st_gid) == -1
 781             || setuid(st.st_uid) == -1) {
 782                 xlog(L_ERROR, "Fail to drop privileges");
 783                 exit(1);
 784         }
 785 }
 786
 787 static void set_kernel_nsm_state(int state)
 788 {
 789         int fd;
 790         const char *file = "/proc/sys/fs/nfs/nsm_local_state";
 791
 792         fd = open(file ,O_WRONLY);
 793         if (fd >= 0) {
 794                 char buf[20];
 795                 snprintf(buf, sizeof(buf), "%d", state);
 796                 if (write(fd, buf, strlen(buf)) != strlen(buf)) {
 797                         xlog_warn("Writing to '%s' failed: errno %d (%m)",
 798                                 file, errno);
 799                 }
 800                 close(fd);
 801         }
 802 }