utils/mountd/cache.c

   1
   2 /*
   3  * Handle communication with knfsd internal cache
   4  *
   5  * We open /proc/net/rpc/{auth.unix.ip,nfsd.export,nfsd.fh}/channel
   6  * and listen for requests (using my_svc_run)
   7  *
   8  */
   9
  10 #ifdef HAVE_CONFIG_H
  11 #include <config.h>
  12 #endif
  13
  14 #include <sys/types.h>
  15 #include <sys/select.h>
  16 #include <sys/stat.h>
  17 #include <time.h>
  18 #include <netinet/in.h>
  19 #include <arpa/inet.h>
  20 #include <unistd.h>
  21 #include <fcntl.h>
  22 #include <errno.h>
  23 #include <ctype.h>
  24 #include <pwd.h>
  25 #include <grp.h>
  26 #include <mntent.h>
  27 #include "misc.h"
  28 #include "nfslib.h"
  29 #include "exportfs.h"
  30 #include "mountd.h"
  31 #include "xmalloc.h"
  32 #include "fsloc.h"
  33
  34 #ifdef USE_BLKID
  35 #include "blkid/blkid.h"
  36 #endif
  37
  38
  39 enum nfsd_fsid {
  40         FSID_DEV = 0,
  41         FSID_NUM,
  42         FSID_MAJOR_MINOR,
  43         FSID_ENCODE_DEV,
  44         FSID_UUID4_INUM,
  45         FSID_UUID8,
  46         FSID_UUID16,
  47         FSID_UUID16_INUM,
  48 };
  49
  50 /*
  51  * Support routines for text-based upcalls.
  52  * Fields are separated by spaces.
  53  * Fields are either mangled to quote space tab newline slosh with slosh
  54  * or a hexified with a leading \x
  55  * Record is terminated with newline.
  56  *
  57  */
  58 int cache_export_ent(char *domain, struct exportent *exp, char *p);
  59
  60
  61 char *lbuf  = NULL;
  62 int lbuflen = 0;
  63
  64 void auth_unix_ip(FILE *f)
  65 {
  66         /* requests are
  67          *  class IP-ADDR
  68          * Ignore if class != "nfsd"
  69          * Otherwise find domainname and write back:
  70          *
  71          *  "nfsd" IP-ADDR expiry domainname
  72          */
  73         char *cp;
  74         char class[20];
  75         char ipaddr[20];
  76         char *client;
  77         struct in_addr addr;
  78         if (readline(fileno(f), &lbuf, &lbuflen) != 1)
  79                 return;
  80
  81         cp = lbuf;
  82
  83         if (qword_get(&cp, class, 20) <= 0 ||
  84             strcmp(class, "nfsd") != 0)
  85                 return;
  86
  87         if (qword_get(&cp, ipaddr, 20) <= 0)
  88                 return;
  89
  90         if (inet_aton(ipaddr, &addr)==0)
  91                 return;
  92
  93         auth_reload();
  94
  95         /* addr is a valid, interesting address, find the domain name... */
  96         client = client_compose(addr);
  97
  98
  99         qword_print(f, "nfsd");
 100         qword_print(f, ipaddr);
 101         qword_printint(f, time(0)+30*60);
 102         if (client)
 103                 qword_print(f, *client?client:"DEFAULT");
 104         qword_eol(f);
 105
 106         if (client) free(client);
 107
 108 }
 109
 110 void auth_unix_gid(FILE *f)
 111 {
 112         /* Request are
 113          *  uid
 114          * reply is
 115          *  uid expiry count list of group ids
 116          */
 117         int uid;
 118         struct passwd *pw;
 119         gid_t glist[100], *groups = glist;
 120         int ngroups = 100;
 121         int rv, i;
 122         char *cp;
 123
 124         if (readline(fileno(f), &lbuf, &lbuflen) != 1)
 125                 return;
 126
 127         cp = lbuf;
 128         if (qword_get_int(&cp, &uid) != 0)
 129                 return;
 130
 131         pw = getpwuid(uid);
 132         if (!pw)
 133                 rv = -1;
 134         else {
 135                 rv = getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
 136                 if (rv == -1 && ngroups >= 100) {
 137                         groups = malloc(sizeof(gid_t)*ngroups);
 138                         if (!groups)
 139                                 rv = -1;
 140                         else
 141                                 rv = getgrouplist(pw->pw_name, pw->pw_gid,
 142                                                   groups, &ngroups);
 143                 }
 144         }
 145         qword_printint(f, uid);
 146         qword_printint(f, time(0)+30*60);
 147         if (rv >= 0) {
 148                 qword_printint(f, ngroups);
 149                 for (i=0; i<ngroups; i++)
 150                         qword_printint(f, groups[i]);
 151         }
 152         qword_eol(f);
 153         if (groups != glist)
 154                 free(groups);
 155 }
 156
 157 #if USE_BLKID
 158 int get_uuid(char *path, char *uuid, int uuidlen, char *u)
 159 {
 160         /* extract hex digits from uuidstr and compose a uuid
 161          * of the given length (max 16), xoring bytes to make
 162          * a smaller uuid.  Then compare with uuid
 163          */
 164         int i = 0;
 165         const char *val;
 166
 167         if (path) {
 168                 static blkid_cache cache = NULL;
 169                 struct stat stb;
 170                 char *devname;
 171                 blkid_tag_iterate iter;
 172                 blkid_dev dev;
 173                 const char *type;
 174                 if (cache == NULL)
 175                         blkid_get_cache(&cache, NULL);
 176
 177                 blkid_probe_all_new(cache);
 178
 179                 if (stat(path, &stb) != 0)
 180                         return 0;
 181                 devname = blkid_devno_to_devname(stb.st_dev);
 182                 if (!devname)
 183                         return 0;
 184                 dev = blkid_get_dev(cache, devname, BLKID_DEV_NORMAL);
 185                 free(devname);
 186                 if (!dev)
 187                         return 0;
 188                 iter = blkid_tag_iterate_begin(dev);
 189                 if (!iter)
 190                         return 0;
 191                 while (blkid_tag_next(iter, &type, &val) == 0)
 192                         if (strcmp(type, "UUID") == 0)
 193                                 break;
 194                 blkid_tag_iterate_end(iter);
 195                 if (!type)
 196                         return 0;
 197         } else {
 198                 val = uuid;
 199         }
 200
 201         memset(u, 0, uuidlen);
 202         for ( ; *val ; val++) {
 203                 char c = *val;
 204                 if (!isxdigit(c))
 205                         continue;
 206                 if (isalpha(c)) {
 207                         if (isupper(c))
 208                                 c = c - 'A' + 10;
 209                         else
 210                                 c = c - 'a' + 10;
 211                 } else
 212                         c = c - '0' + 0;
 213                 if ((i&1) == 0)
 214                         c <<= 4;
 215                 u[i/2] ^= c;
 216                 i++;
 217                 if (i == uuidlen*2)
 218                         i = 0;
 219         }
 220         return 1;
 221 }
 222 #endif
 223
 224 /* Iterate through /etc/mtab, finding mountpoints
 225  * at or below a given path
 226  */
 227 static char *next_mnt(void **v, char *p)
 228 {
 229         FILE *f;
 230         struct mntent *me;
 231         int l = strlen(p);
 232         if (*v == NULL) {
 233                 f = setmntent("/etc/mtab", "r");
 234                 *v = f;
 235         } else
 236                 f = *v;
 237         while ((me = getmntent(f)) != NULL &&
 238                (strncmp(me->mnt_dir, p, l) != 0 ||
 239                 me->mnt_dir[l] != '/'))
 240                 ;
 241         if (me == NULL) {
 242                 endmntent(f);
 243                 *v = NULL;
 244                 return NULL;
 245         }
 246         return me->mnt_dir;
 247 }
 248
 249 void nfsd_fh(FILE *f)
 250 {
 251         /* request are:
 252          *  domain fsidtype fsid
 253          * interpret fsid, find export point and options, and write:
 254          *  domain fsidtype fsid expiry path
 255          */
 256         char *cp;
 257         char *dom;
 258         int fsidtype;
 259         int fsidlen;
 260         unsigned int dev, major=0, minor=0;
 261         unsigned int inode=0;
 262         unsigned long long inode64;
 263         unsigned int fsidnum=0;
 264         char fsid[32];
 265         struct exportent *found = NULL;
 266         char *found_path = NULL;
 267         nfs_export *exp;
 268         int i;
 269         int dev_missing = 0;
 270         int uuidlen = 0;
 271         char *fhuuid = NULL;
 272
 273         if (readline(fileno(f), &lbuf, &lbuflen) != 1)
 274                 return;
 275
 276         cp = lbuf;
 277
 278         dom = malloc(strlen(cp));
 279         if (dom == NULL)
 280                 return;
 281         if (qword_get(&cp, dom, strlen(cp)) <= 0)
 282                 goto out;
 283         if (qword_get_int(&cp, &fsidtype) != 0)
 284                 goto out;
 285         if (fsidtype < 0 || fsidtype > 7)
 286                 goto out; /* unknown type */
 287         if ((fsidlen = qword_get(&cp, fsid, 32)) <= 0)
 288                 goto out;
 289         switch(fsidtype) {
 290         case FSID_DEV: /* 4 bytes: 2 major, 2 minor, 4 inode */
 291                 if (fsidlen != 8)
 292                         goto out;
 293                 memcpy(&dev, fsid, 4);
 294                 memcpy(&inode, fsid+4, 4);
 295                 major = ntohl(dev)>>16;
 296                 minor = ntohl(dev) & 0xFFFF;
 297                 break;
 298
 299         case FSID_NUM: /* 4 bytes - fsid */
 300                 if (fsidlen != 4)
 301                         goto out;
 302                 memcpy(&fsidnum, fsid, 4);
 303                 break;
 304
 305         case FSID_MAJOR_MINOR: /* 12 bytes: 4 major, 4 minor, 4 inode
 306                  * This format is never actually used but was
 307                  * an historical accident
 308                  */
 309                 if (fsidlen != 12)
 310                         goto out;
 311                 memcpy(&dev, fsid, 4); major = ntohl(dev);
 312                 memcpy(&dev, fsid+4, 4); minor = ntohl(dev);
 313                 memcpy(&inode, fsid+8, 4);
 314                 break;
 315
 316         case FSID_ENCODE_DEV: /* 8 bytes: 4 byte packed device number, 4 inode */
 317                 /* This is *host* endian, not net-byte-order, because
 318                  * no-one outside this host has any business interpreting it
 319                  */
 320                 if (fsidlen != 8)
 321                         goto out;
 322                 memcpy(&dev, fsid, 4);
 323                 memcpy(&inode, fsid+4, 4);
 324                 major = (dev & 0xfff00) >> 8;
 325                 minor = (dev & 0xff) | ((dev >> 12) & 0xfff00);
 326                 break;
 327
 328         case FSID_UUID4_INUM: /* 4 byte inode number and 4 byte uuid */
 329                 if (fsidlen != 8)
 330                         goto out;
 331                 memcpy(&inode, fsid, 4);
 332                 uuidlen = 4;
 333                 fhuuid = fsid+4;
 334                 break;
 335         case FSID_UUID8: /* 8 byte uuid */
 336                 if (fsidlen != 8)
 337                         goto out;
 338                 uuidlen = 8;
 339                 fhuuid = fsid;
 340                 break;
 341         case FSID_UUID16: /* 16 byte uuid */
 342                 if (fsidlen != 16)
 343                         goto out;
 344                 uuidlen = 16;
 345                 fhuuid = fsid;
 346                 break;
 347         case FSID_UUID16_INUM: /* 8 byte inode number and 16 byte uuid */
 348                 if (fsidlen != 24)
 349                         goto out;
 350                 memcpy(&inode64, fsid, 8);
 351                 inode = inode64;
 352                 uuidlen = 16;
 353                 fhuuid = fsid+8;
 354                 break;
 355         }
 356
 357         auth_reload();
 358
 359         /* Now determine export point for this fsid/domain */
 360         for (i=0 ; i < MCL_MAXTYPES; i++) {
 361                 nfs_export *next_exp;
 362                 for (exp = exportlist[i]; exp; exp = next_exp) {
 363                         struct stat stb;
 364                         char u[16];
 365                         char *path;
 366
 367                         if (exp->m_export.e_flags & NFSEXP_CROSSMOUNT) {
 368                                 static nfs_export *prev = NULL;
 369                                 static void *mnt = NULL;
 370
 371                                 if (prev == exp) {
 372                                         /* try a submount */
 373                                         path = next_mnt(&mnt, exp->m_export.e_path);
 374                                         if (!path) {
 375                                                 next_exp = exp->m_next;
 376                                                 prev = NULL;
 377                                                 continue;
 378                                         }
 379                                         next_exp = exp;
 380                                 } else {
 381                                         prev = exp;
 382                                         mnt = NULL;
 383                                         path = exp->m_export.e_path;
 384                                         next_exp = exp;
 385                                 }
 386                         } else {
 387                                 path = exp->m_export.e_path;
 388                                 next_exp = exp->m_next;
 389                         }
 390
 391                         if (!client_member(dom, exp->m_client->m_hostname))
 392                                 continue;
 393                         if (exp->m_export.e_mountpoint &&
 394                             !is_mountpoint(exp->m_export.e_mountpoint[0]?
 395                                            exp->m_export.e_mountpoint:
 396                                            exp->m_export.e_path))
 397                                 dev_missing ++;
 398                         if (stat(path, &stb) != 0)
 399                                 continue;
 400                         if (!S_ISDIR(stb.st_mode) && !S_ISREG(stb.st_mode)) {
 401                                 continue;
 402                         }
 403                         switch(fsidtype){
 404                         case FSID_DEV:
 405                         case FSID_MAJOR_MINOR:
 406                         case FSID_ENCODE_DEV:
 407                                 if (stb.st_ino != inode)
 408                                         continue;
 409                                 if (major != major(stb.st_dev) ||
 410                                     minor != minor(stb.st_dev))
 411                                         continue;
 412                                 break;
 413                         case FSID_NUM:
 414                                 if (((exp->m_export.e_flags & NFSEXP_FSID) == 0 ||
 415                                      exp->m_export.e_fsid != fsidnum))
 416                                         continue;
 417                                 break;
 418                         case FSID_UUID4_INUM:
 419                         case FSID_UUID16_INUM:
 420                                 if (stb.st_ino != inode)
 421                                         continue;
 422                                 goto check_uuid;
 423                         case FSID_UUID8:
 424                         case FSID_UUID16:
 425                                 if (!is_mountpoint(path))
 426                                         continue;
 427                         check_uuid:
 428 #if USE_BLKID
 429                                 if (exp->m_export.e_uuid)
 430                                         get_uuid(NULL, exp->m_export.e_uuid,
 431                                                  uuidlen, u);
 432                                 else if (get_uuid(path, NULL,
 433                                                   uuidlen, u) == 0)
 434                                         continue;
 435
 436                                 if (memcmp(u, fhuuid, uuidlen) != 0)
 437                                         continue;
 438                                 break;
 439 #else
 440                                 continue;
 441 #endif
 442                         }
 443                         /* It's a match !! */
 444                         if (!found) {
 445                                 found = &exp->m_export;
 446                                 found_path = strdup(path);
 447                         } else if (strcmp(found->e_path, exp->m_export.e_path)!= 0)
 448                         {
 449                                 xlog(L_WARNING, "%s and %s have same filehandle for %s, using first",
 450                                      found_path, path, dom);
 451                         }
 452                 }
 453         }
 454         if (found &&
 455             found->e_mountpoint &&
 456             !is_mountpoint(found->e_mountpoint[0]?
 457                            found->e_mountpoint:
 458                            found->e_path)) {
 459                 /* Cannot export this yet
 460                  * should log a warning, but need to rate limit
 461                    xlog(L_WARNING, "%s not exported as %d not a mountpoint",
 462                    found->e_path, found->e_mountpoint);
 463                  */
 464                 /* FIXME we need to make sure we re-visit this later */
 465                 goto out;
 466         }
 467         if (!found && dev_missing) {
 468                 /* The missing dev could be what we want, so just be
 469                  * quite rather than returning stale yet
 470                  */
 471                 goto out;
 472         }
 473
 474         if (found)
 475                 if (cache_export_ent(dom, found, found_path) < 0)
 476                         found = 0;
 477
 478         qword_print(f, dom);
 479         qword_printint(f, fsidtype);
 480         qword_printhex(f, fsid, fsidlen);
 481         /* The fsid -> path lookup can be quite expensive as it
 482          * potentially stats and reads lots of devices, and some of those
 483          * might have spun-down.  The Answer is not likely to
 484          * change underneath us, and an 'exportfs -f' can always
 485          * remove this from the kernel, so use a really log
 486          * timeout.  Maybe this should be configurable on the command
 487          * line.
 488          */
 489         qword_printint(f, 0x7fffffff);
 490         if (found)
 491                 qword_print(f, found->e_path);
 492         qword_eol(f);
 493  out:
 494         free(dom);
 495         return;
 496 }
 497
 498 static void write_fsloc(FILE *f, struct exportent *ep, char *path)
 499 {
 500         struct servers *servers;
 501
 502         if (ep->e_fslocmethod == FSLOC_NONE)
 503                 return;
 504
 505         servers = replicas_lookup(ep->e_fslocmethod, ep->e_fslocdata, path);
 506         if (!servers)
 507                 return;
 508         qword_print(f, "fsloc");
 509         qword_printint(f, servers->h_num);
 510         if (servers->h_num >= 0) {
 511                 int i;
 512                 for (i=0; i<servers->h_num; i++) {
 513                         qword_print(f, servers->h_mp[i]->h_host);
 514                         qword_print(f, servers->h_mp[i]->h_path);
 515                 }
 516         }
 517         qword_printint(f, servers->h_referral);
 518         release_replicas(servers);
 519 }
 520
 521 static int dump_to_cache(FILE *f, char *domain, char *path, struct exportent *exp)
 522 {
 523         qword_print(f, domain);
 524         qword_print(f, path);
 525         qword_printint(f, time(0)+30*60);
 526         if (exp) {
 527                 qword_printint(f, exp->e_flags);
 528                 qword_printint(f, exp->e_anonuid);
 529                 qword_printint(f, exp->e_anongid);
 530                 qword_printint(f, exp->e_fsid);
 531                 write_fsloc(f, exp, path);
 532 #if USE_BLKID
 533                 if (exp->e_uuid == NULL) {
 534                         char u[16];
 535                         if (get_uuid(path, NULL, 16, u)) {
 536                                 qword_print(f, "uuid");
 537                                 qword_printhex(f, u, 16);
 538                         }
 539                 } else if (exp->e_uuid) {
 540                         qword_print(f, "uuid");
 541                         qword_printhex(f, exp->e_uuid, 16);
 542                 }
 543 #endif
 544         }
 545         return qword_eol(f);
 546 }
 547
 548 void nfsd_export(FILE *f)
 549 {
 550         /* requests are:
 551          *  domain path
 552          * determine export options and return:
 553          *  domain path expiry flags anonuid anongid fsid
 554          */
 555
 556         char *cp;
 557         int i;
 558         char *dom, *path;
 559         nfs_export *exp, *found = NULL;
 560         int found_type = 0;
 561
 562
 563         if (readline(fileno(f), &lbuf, &lbuflen) != 1)
 564                 return;
 565
 566         cp = lbuf;
 567         dom = malloc(strlen(cp));
 568         path = malloc(strlen(cp));
 569
 570         if (!dom || !path)
 571                 goto out;
 572
 573         if (qword_get(&cp, dom, strlen(lbuf)) <= 0)
 574                 goto out;
 575         if (qword_get(&cp, path, strlen(lbuf)) <= 0)
 576                 goto out;
 577
 578         auth_reload();
 579
 580         /* now find flags for this export point in this domain */
 581         for (i=0 ; i < MCL_MAXTYPES; i++) {
 582                 for (exp = exportlist[i]; exp; exp = exp->m_next) {
 583                         if (!client_member(dom, exp->m_client->m_hostname))
 584                                 continue;
 585                         if (exp->m_export.e_flags & NFSEXP_CROSSMOUNT) {
 586                                 /* if path is a mountpoint below e_path, then OK */
 587                                 int l = strlen(exp->m_export.e_path);
 588                                 if (strcmp(path, exp->m_export.e_path) == 0 ||
 589                                     (strncmp(path, exp->m_export.e_path, l) == 0 &&
 590                                      path[l] == '/' &&
 591                                      is_mountpoint(path)))
 592                                         /* ok */;
 593                                 else
 594                                         continue;
 595                         } else if (strcmp(path, exp->m_export.e_path) != 0)
 596                                 continue;
 597                         if (!found) {
 598                                 found = exp;
 599                                 found_type = i;
 600                                 continue;
 601                         }
 602                         /* If one is a CROSSMOUNT, then prefer the longest path */
 603                         if (((found->m_export.e_flags & NFSEXP_CROSSMOUNT) ||
 604                              (found->m_export.e_flags & NFSEXP_CROSSMOUNT)) &&
 605                             strlen(found->m_export.e_path) !=
 606                             strlen(found->m_export.e_path)) {
 607
 608                                 if (strlen(exp->m_export.e_path) >
 609                                     strlen(found->m_export.e_path)) {
 610                                         found = exp;
 611                                         found_type = i;
 612                                 }
 613                                 continue;
 614
 615                         } else if (found_type == i && found->m_warned == 0) {
 616                                 xlog(L_WARNING, "%s exported to both %s and %s, "
 617                                      "arbitrarily choosing options from first",
 618                                      path, found->m_client->m_hostname, exp->m_client->m_hostname,
 619                                      dom);
 620                                 found->m_warned = 1;
 621                         }
 622                 }
 623         }
 624
 625         if (found) {
 626                 if (dump_to_cache(f, dom, path, &found->m_export) < 0) {
 627                         xlog(L_WARNING,
 628                              "Cannot export %s, possibly unsupported filesystem"
 629                              " or fsid= required", path);
 630                         dump_to_cache(f, dom, path, NULL);
 631                 } else
 632                         mountlist_add(dom, path);
 633         } else {
 634                 dump_to_cache(f, dom, path, NULL);
 635         }
 636  out:
 637         if (dom) free(dom);
 638         if (path) free(path);
 639 }
 640
 641
 642 struct {
 643         char *cache_name;
 644         void (*cache_handle)(FILE *f);
 645         FILE *f;
 646 } cachelist[] = {
 647         { "auth.unix.ip", auth_unix_ip},
 648         { "auth.unix.gid", auth_unix_gid},
 649         { "nfsd.export", nfsd_export},
 650         { "nfsd.fh", nfsd_fh},
 651         { NULL, NULL }
 652 };
 653
 654 extern int manage_gids;
 655 void cache_open(void)
 656 {
 657         int i;
 658         for (i=0; cachelist[i].cache_name; i++ ) {
 659                 char path[100];
 660                 if (!manage_gids && cachelist[i].cache_handle == auth_unix_gid)
 661                         continue;
 662                 sprintf(path, "/proc/net/rpc/%s/channel", cachelist[i].cache_name);
 663                 cachelist[i].f = fopen(path, "r+");
 664         }
 665 }
 666
 667 void cache_set_fds(fd_set *fdset)
 668 {
 669         int i;
 670         for (i=0; cachelist[i].cache_name; i++) {
 671                 if (cachelist[i].f)
 672                         FD_SET(fileno(cachelist[i].f), fdset);
 673         }
 674 }
 675
 676 int cache_process_req(fd_set *readfds)
 677 {
 678         int i;
 679         int cnt = 0;
 680         for (i=0; cachelist[i].cache_name; i++) {
 681                 if (cachelist[i].f != NULL &&
 682                     FD_ISSET(fileno(cachelist[i].f), readfds)) {
 683                         cnt++;
 684                         cachelist[i].cache_handle(cachelist[i].f);
 685                         FD_CLR(fileno(cachelist[i].f), readfds);
 686                 }
 687         }
 688         return cnt;
 689 }
 690
 691
 692 /*
 693  * Give IP->domain and domain+path->options to kernel
 694  * % echo nfsd $IP  $[now+30*60] $domain > /proc/net/rpc/auth.unix.ip/channel
 695  * % echo $domain $path $[now+30*60] $options $anonuid $anongid $fsid > /proc/net/rpc/nfsd.export/channel
 696  */
 697
 698 int cache_export_ent(char *domain, struct exportent *exp, char *path)
 699 {
 700         int err;
 701         FILE *f = fopen("/proc/net/rpc/nfsd.export/channel", "w");
 702         if (!f)
 703                 return -1;
 704
 705         err = dump_to_cache(f, domain, exp->e_path, exp);
 706         if (err) {
 707                 xlog(L_WARNING,
 708                      "Cannot export %s, possibly unsupported filesystem or"
 709                      " fsid= required", exp->e_path);
 710         }
 711         mountlist_add(domain, exp->e_path);
 712
 713         while (err == 0 && (exp->e_flags & NFSEXP_CROSSMOUNT) && path) {
 714                 /* really an 'if', but we can break out of
 715                  * a 'while' more easily */
 716                 /* Look along 'path' for other filesystems
 717                  * and export them with the same options
 718                  */
 719                 struct stat stb;
 720                 int l = strlen(exp->e_path);
 721                 int dev;
 722
 723                 if (strlen(path) <= l || path[l] != '/' ||
 724                     strncmp(exp->e_path, path, l) != 0)
 725                         break;
 726                 if (stat(exp->e_path, &stb) != 0)
 727                         break;
 728                 dev = stb.st_dev;
 729                 while(path[l] == '/') {
 730                         char c;
 731                         /* errors for submount should fail whole filesystem */
 732                         int err2;
 733
 734                         l++;
 735                         while (path[l] != '/' && path[l])
 736                                 l++;
 737                         c = path[l];
 738                         path[l] = 0;
 739                         err2 = lstat(path, &stb);
 740                         path[l] = c;
 741                         if (err2 < 0)
 742                                 break;
 743                         if (stb.st_dev == dev)
 744                                 continue;
 745                         dev = stb.st_dev;
 746                         path[l] = 0;
 747                         dump_to_cache(f, domain, path, exp);
 748                         path[l] = c;
 749                 }
 750                 break;
 751         }
 752
 753         fclose(f);
 754         return err;
 755 }
 756
 757 int cache_export(nfs_export *exp, char *path)
 758 {
 759         int err;
 760         FILE *f;
 761
 762         f = fopen("/proc/net/rpc/auth.unix.ip/channel", "w");
 763         if (!f)
 764                 return -1;
 765
 766         qword_print(f, "nfsd");
 767         qword_print(f, inet_ntoa(exp->m_client->m_addrlist[0]));
 768         qword_printint(f, time(0)+30*60);
 769         qword_print(f, exp->m_client->m_hostname);
 770         err = qword_eol(f);
 771
 772         fclose(f);
 773
 774         err = cache_export_ent(exp->m_client->m_hostname, &exp->m_export, path)
 775                 || err;
 776         return err;
 777 }
 778
 779 /* Get a filehandle.
 780  * {
 781  *   echo $domain $path $length
 782  *   read filehandle <&0
 783  * } <> /proc/fs/nfsd/filehandle
 784  */
 785 struct nfs_fh_len *
 786 cache_get_filehandle(nfs_export *exp, int len, char *p)
 787 {
 788         FILE *f = fopen("/proc/fs/nfsd/filehandle", "r+");
 789         char buf[200];
 790         char *bp = buf;
 791         int failed;
 792         static struct nfs_fh_len fh;
 793
 794         if (!f)
 795                 f = fopen("/proc/fs/nfs/filehandle", "r+");
 796         if (!f)
 797                 return NULL;
 798
 799         qword_print(f, exp->m_client->m_hostname);
 800         qword_print(f, p);
 801         qword_printint(f, len);
 802         failed = qword_eol(f);
 803
 804         if (!failed)
 805                 failed = (fgets(buf, sizeof(buf), f) == NULL);
 806         fclose(f);
 807         if (failed)
 808                 return NULL;
 809         memset(fh.fh_handle, 0, sizeof(fh.fh_handle));
 810         fh.fh_size = qword_get(&bp, (char *)fh.fh_handle, NFS3_FHSIZE);
 811         return &fh;
 812 }
 813