fs/nfsd/nfsfh.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * NFS server file handle treatment.
   4  *
   5  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
   6  * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
   7  * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
   8  * ... and again Southern-Winter 2001 to support export_operations
   9  */
  10
  11 #include <linux/exportfs.h>
  12
  13 #include <linux/sunrpc/svcauth_gss.h>
  14 #include "nfsd.h"
  15 #include "vfs.h"
  16 #include "auth.h"
  17
  18 #define NFSDDBG_FACILITY                NFSDDBG_FH
  19
  20
  21 /*
  22  * our acceptability function.
  23  * if NOSUBTREECHECK, accept anything
  24  * if not, require that we can walk up to exp->ex_dentry
  25  * doing some checks on the 'x' bits
  26  */
  27 static int nfsd_acceptable(void *expv, struct dentry *dentry)
  28 {
  29         struct svc_export *exp = expv;
  30         int rv;
  31         struct dentry *tdentry;
  32         struct dentry *parent;
  33
  34         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
  35                 return 1;
  36
  37         tdentry = dget(dentry);
  38         while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
  39                 /* make sure parents give x permission to user */
  40                 int err;
  41                 parent = dget_parent(tdentry);
  42                 err = inode_permission(d_inode(parent), MAY_EXEC);
  43                 if (err < 0) {
  44                         dput(parent);
  45                         break;
  46                 }
  47                 dput(tdentry);
  48                 tdentry = parent;
  49         }
  50         if (tdentry != exp->ex_path.dentry)
  51                 dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry);
  52         rv = (tdentry == exp->ex_path.dentry);
  53         dput(tdentry);
  54         return rv;
  55 }
  56
  57 /* Type check. The correct error return for type mismatches does not seem to be
  58  * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
  59  * comment in the NFSv3 spec says this is incorrect (implementation notes for
  60  * the write call).
  61  */
  62 static inline __be32
  63 nfsd_mode_check(struct svc_rqst *rqstp, struct dentry *dentry,
  64                 umode_t requested)
  65 {
  66         umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
  67
  68         if (requested == 0) /* the caller doesn't care */
  69                 return nfs_ok;
  70         if (mode == requested) {
  71                 if (mode == S_IFDIR && !d_can_lookup(dentry)) {
  72                         WARN_ON_ONCE(1);
  73                         return nfserr_notdir;
  74                 }
  75                 return nfs_ok;
  76         }
  77         /*
  78          * v4 has an error more specific than err_notdir which we should
  79          * return in preference to err_notdir:
  80          */
  81         if (rqstp->rq_vers == 4 && mode == S_IFLNK)
  82                 return nfserr_symlink;
  83         if (requested == S_IFDIR)
  84                 return nfserr_notdir;
  85         if (mode == S_IFDIR)
  86                 return nfserr_isdir;
  87         return nfserr_inval;
  88 }
  89
  90 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
  91                                           struct svc_export *exp)
  92 {
  93         int flags = nfsexp_flags(rqstp, exp);
  94
  95         /* Check if the request originated from a secure port. */
  96         if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && !(flags & NFSEXP_INSECURE_PORT)) {
  97                 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
  98                 dprintk("nfsd: request from insecure port %s!\n",
  99                         svc_print_addr(rqstp, buf, sizeof(buf)));
 100                 return nfserr_perm;
 101         }
 102
 103         /* Set user creds for this exportpoint */
 104         return nfserrno(nfsd_setuser(rqstp, exp));
 105 }
 106
 107 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
 108         struct dentry *dentry, struct svc_export *exp)
 109 {
 110         if (!(exp->ex_flags & NFSEXP_V4ROOT))
 111                 return nfs_ok;
 112         /*
 113          * v2/v3 clients have no need for the V4ROOT export--they use
 114          * the mount protocl instead; also, further V4ROOT checks may be
 115          * in v4-specific code, in which case v2/v3 clients could bypass
 116          * them.
 117          */
 118         if (!nfsd_v4client(rqstp))
 119                 return nfserr_stale;
 120         /*
 121          * We're exposing only the directories and symlinks that have to be
 122          * traversed on the way to real exports:
 123          */
 124         if (unlikely(!d_is_dir(dentry) &&
 125                      !d_is_symlink(dentry)))
 126                 return nfserr_stale;
 127         /*
 128          * A pseudoroot export gives permission to access only one
 129          * single directory; the kernel has to make another upcall
 130          * before granting access to anything else under it:
 131          */
 132         if (unlikely(dentry != exp->ex_path.dentry))
 133                 return nfserr_stale;
 134         return nfs_ok;
 135 }
 136
 137 /*
 138  * Use the given filehandle to look up the corresponding export and
 139  * dentry.  On success, the results are used to set fh_export and
 140  * fh_dentry.
 141  */
 142 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 143 {
 144         struct knfsd_fh *fh = &fhp->fh_handle;
 145         struct fid *fid = NULL, sfid;
 146         struct svc_export *exp;
 147         struct dentry *dentry;
 148         int fileid_type;
 149         int data_left = fh->fh_size/4;
 150         __be32 error;
 151
 152         error = nfserr_stale;
 153         if (rqstp->rq_vers > 2)
 154                 error = nfserr_badhandle;
 155         if (rqstp->rq_vers == 4 && fh->fh_size == 0)
 156                 return nfserr_nofilehandle;
 157
 158         if (fh->fh_version == 1) {
 159                 int len;
 160
 161                 if (--data_left < 0)
 162                         return error;
 163                 if (fh->fh_auth_type != 0)
 164                         return error;
 165                 len = key_len(fh->fh_fsid_type) / 4;
 166                 if (len == 0)
 167                         return error;
 168                 if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
 169                         /* deprecated, convert to type 3 */
 170                         len = key_len(FSID_ENCODE_DEV)/4;
 171                         fh->fh_fsid_type = FSID_ENCODE_DEV;
 172                         /*
 173                          * struct knfsd_fh uses host-endian fields, which are
 174                          * sometimes used to hold net-endian values. This
 175                          * confuses sparse, so we must use __force here to
 176                          * keep it from complaining.
 177                          */
 178                         fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
 179                                                         ntohl((__force __be32)fh->fh_fsid[1])));
 180                         fh->fh_fsid[1] = fh->fh_fsid[2];
 181                 }
 182                 data_left -= len;
 183                 if (data_left < 0)
 184                         return error;
 185                 exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
 186                 fid = (struct fid *)(fh->fh_fsid + len);
 187         } else {
 188                 __u32 tfh[2];
 189                 dev_t xdev;
 190                 ino_t xino;
 191
 192                 if (fh->fh_size != NFS_FHSIZE)
 193                         return error;
 194                 /* assume old filehandle format */
 195                 xdev = old_decode_dev(fh->ofh_xdev);
 196                 xino = u32_to_ino_t(fh->ofh_xino);
 197                 mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
 198                 exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
 199         }
 200
 201         error = nfserr_stale;
 202         if (PTR_ERR(exp) == -ENOENT)
 203                 return error;
 204
 205         if (IS_ERR(exp))
 206                 return nfserrno(PTR_ERR(exp));
 207
 208         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
 209                 /* Elevate privileges so that the lack of 'r' or 'x'
 210                  * permission on some parent directory will
 211                  * not stop exportfs_decode_fh from being able
 212                  * to reconnect a directory into the dentry cache.
 213                  * The same problem can affect "SUBTREECHECK" exports,
 214                  * but as nfsd_acceptable depends on correct
 215                  * access control settings being in effect, we cannot
 216                  * fix that case easily.
 217                  */
 218                 struct cred *new = prepare_creds();
 219                 if (!new) {
 220                         error =  nfserrno(-ENOMEM);
 221                         goto out;
 222                 }
 223                 new->cap_effective =
 224                         cap_raise_nfsd_set(new->cap_effective,
 225                                            new->cap_permitted);
 226                 put_cred(override_creds(new));
 227                 put_cred(new);
 228         } else {
 229                 error = nfsd_setuser_and_check_port(rqstp, exp);
 230                 if (error)
 231                         goto out;
 232         }
 233
 234         /*
 235          * Look up the dentry using the NFS file handle.
 236          */
 237         error = nfserr_stale;
 238         if (rqstp->rq_vers > 2)
 239                 error = nfserr_badhandle;
 240
 241         if (fh->fh_version != 1) {
 242                 sfid.i32.ino = fh->ofh_ino;
 243                 sfid.i32.gen = fh->ofh_generation;
 244                 sfid.i32.parent_ino = fh->ofh_dirino;
 245                 fid = &sfid;
 246                 data_left = 3;
 247                 if (fh->ofh_dirino == 0)
 248                         fileid_type = FILEID_INO32_GEN;
 249                 else
 250                         fileid_type = FILEID_INO32_GEN_PARENT;
 251         } else
 252                 fileid_type = fh->fh_fileid_type;
 253
 254         if (fileid_type == FILEID_ROOT)
 255                 dentry = dget(exp->ex_path.dentry);
 256         else {
 257                 dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
 258                                 data_left, fileid_type,
 259                                 nfsd_acceptable, exp);
 260         }
 261         if (dentry == NULL)
 262                 goto out;
 263         if (IS_ERR(dentry)) {
 264                 if (PTR_ERR(dentry) != -EINVAL)
 265                         error = nfserrno(PTR_ERR(dentry));
 266                 goto out;
 267         }
 268
 269         if (d_is_dir(dentry) &&
 270                         (dentry->d_flags & DCACHE_DISCONNECTED)) {
 271                 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
 272                                 dentry);
 273         }
 274
 275         fhp->fh_dentry = dentry;
 276         fhp->fh_export = exp;
 277         return 0;
 278 out:
 279         exp_put(exp);
 280         return error;
 281 }
 282
 283 /**
 284  * fh_verify - filehandle lookup and access checking
 285  * @rqstp: pointer to current rpc request
 286  * @fhp: filehandle to be verified
 287  * @type: expected type of object pointed to by filehandle
 288  * @access: type of access needed to object
 289  *
 290  * Look up a dentry from the on-the-wire filehandle, check the client's
 291  * access to the export, and set the current task's credentials.
 292  *
 293  * Regardless of success or failure of fh_verify(), fh_put() should be
 294  * called on @fhp when the caller is finished with the filehandle.
 295  *
 296  * fh_verify() may be called multiple times on a given filehandle, for
 297  * example, when processing an NFSv4 compound.  The first call will look
 298  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
 299  * skip the lookup and just perform the other checks and possibly change
 300  * the current task's credentials.
 301  *
 302  * @type specifies the type of object expected using one of the S_IF*
 303  * constants defined in include/linux/stat.h.  The caller may use zero
 304  * to indicate that it doesn't care, or a negative integer to indicate
 305  * that it expects something not of the given type.
 306  *
 307  * @access is formed from the NFSD_MAY_* constants defined in
 308  * fs/nfsd/vfs.h.
 309  */
 310 __be32
 311 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
 312 {
 313         struct svc_export *exp;
 314         struct dentry   *dentry;
 315         __be32          error;
 316
 317         dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
 318
 319         if (!fhp->fh_dentry) {
 320                 error = nfsd_set_fh_dentry(rqstp, fhp);
 321                 if (error)
 322                         goto out;
 323         }
 324         dentry = fhp->fh_dentry;
 325         exp = fhp->fh_export;
 326         /*
 327          * We still have to do all these permission checks, even when
 328          * fh_dentry is already set:
 329          *      - fh_verify may be called multiple times with different
 330          *        "access" arguments (e.g. nfsd_proc_create calls
 331          *        fh_verify(...,NFSD_MAY_EXEC) first, then later (in
 332          *        nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
 333          *      - in the NFSv4 case, the filehandle may have been filled
 334          *        in by fh_compose, and given a dentry, but further
 335          *        compound operations performed with that filehandle
 336          *        still need permissions checks.  In the worst case, a
 337          *        mountpoint crossing may have changed the export
 338          *        options, and we may now need to use a different uid
 339          *        (for example, if different id-squashing options are in
 340          *        effect on the new filesystem).
 341          */
 342         error = check_pseudo_root(rqstp, dentry, exp);
 343         if (error)
 344                 goto out;
 345
 346         error = nfsd_setuser_and_check_port(rqstp, exp);
 347         if (error)
 348                 goto out;
 349
 350         error = nfsd_mode_check(rqstp, dentry, type);
 351         if (error)
 352                 goto out;
 353
 354         /*
 355          * pseudoflavor restrictions are not enforced on NLM,
 356          * which clients virtually always use auth_sys for,
 357          * even while using RPCSEC_GSS for NFS.
 358          */
 359         if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
 360                 goto skip_pseudoflavor_check;
 361         /*
 362          * Clients may expect to be able to use auth_sys during mount,
 363          * even if they use gss for everything else; see section 2.3.2
 364          * of rfc 2623.
 365          */
 366         if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
 367                         && exp->ex_path.dentry == dentry)
 368                 goto skip_pseudoflavor_check;
 369
 370         error = check_nfsd_access(exp, rqstp);
 371         if (error)
 372                 goto out;
 373
 374 skip_pseudoflavor_check:
 375         /* Finally, check access permissions. */
 376         error = nfsd_permission(rqstp, exp, dentry, access);
 377
 378         if (error) {
 379                 dprintk("fh_verify: %pd2 permission failure, "
 380                         "acc=%x, error=%d\n",
 381                         dentry,
 382                         access, ntohl(error));
 383         }
 384 out:
 385         if (error == nfserr_stale)
 386                 nfsdstats.fh_stale++;
 387         return error;
 388 }
 389
 390
 391 /*
 392  * Compose a file handle for an NFS reply.
 393  *
 394  * Note that when first composed, the dentry may not yet have
 395  * an inode.  In this case a call to fh_update should be made
 396  * before the fh goes out on the wire ...
 397  */
 398 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
 399                 struct dentry *dentry)
 400 {
 401         if (dentry != exp->ex_path.dentry) {
 402                 struct fid *fid = (struct fid *)
 403                         (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
 404                 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
 405                 int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
 406
 407                 fhp->fh_handle.fh_fileid_type =
 408                         exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
 409                 fhp->fh_handle.fh_size += maxsize * 4;
 410         } else {
 411                 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
 412         }
 413 }
 414
 415 /*
 416  * for composing old style file handles
 417  */
 418 static inline void _fh_update_old(struct dentry *dentry,
 419                                   struct svc_export *exp,
 420                                   struct knfsd_fh *fh)
 421 {
 422         fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
 423         fh->ofh_generation = d_inode(dentry)->i_generation;
 424         if (d_is_dir(dentry) ||
 425             (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
 426                 fh->ofh_dirino = 0;
 427 }
 428
 429 static bool is_root_export(struct svc_export *exp)
 430 {
 431         return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
 432 }
 433
 434 static struct super_block *exp_sb(struct svc_export *exp)
 435 {
 436         return exp->ex_path.dentry->d_sb;
 437 }
 438
 439 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
 440 {
 441         switch (fsid_type) {
 442         case FSID_DEV:
 443                 if (!old_valid_dev(exp_sb(exp)->s_dev))
 444                         return 0;
 445                 /* FALL THROUGH */
 446         case FSID_MAJOR_MINOR:
 447         case FSID_ENCODE_DEV:
 448                 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
 449         case FSID_NUM:
 450                 return exp->ex_flags & NFSEXP_FSID;
 451         case FSID_UUID8:
 452         case FSID_UUID16:
 453                 if (!is_root_export(exp))
 454                         return 0;
 455                 /* fall through */
 456         case FSID_UUID4_INUM:
 457         case FSID_UUID16_INUM:
 458                 return exp->ex_uuid != NULL;
 459         }
 460         return 1;
 461 }
 462
 463
 464 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
 465 {
 466         u8 version;
 467         u8 fsid_type;
 468 retry:
 469         version = 1;
 470         if (ref_fh && ref_fh->fh_export == exp) {
 471                 version = ref_fh->fh_handle.fh_version;
 472                 fsid_type = ref_fh->fh_handle.fh_fsid_type;
 473
 474                 ref_fh = NULL;
 475
 476                 switch (version) {
 477                 case 0xca:
 478                         fsid_type = FSID_DEV;
 479                         break;
 480                 case 1:
 481                         break;
 482                 default:
 483                         goto retry;
 484                 }
 485
 486                 /*
 487                  * As the fsid -> filesystem mapping was guided by
 488                  * user-space, there is no guarantee that the filesystem
 489                  * actually supports that fsid type. If it doesn't we
 490                  * loop around again without ref_fh set.
 491                  */
 492                 if (!fsid_type_ok_for_exp(fsid_type, exp))
 493                         goto retry;
 494         } else if (exp->ex_flags & NFSEXP_FSID) {
 495                 fsid_type = FSID_NUM;
 496         } else if (exp->ex_uuid) {
 497                 if (fhp->fh_maxsize >= 64) {
 498                         if (is_root_export(exp))
 499                                 fsid_type = FSID_UUID16;
 500                         else
 501                                 fsid_type = FSID_UUID16_INUM;
 502                 } else {
 503                         if (is_root_export(exp))
 504                                 fsid_type = FSID_UUID8;
 505                         else
 506                                 fsid_type = FSID_UUID4_INUM;
 507                 }
 508         } else if (!old_valid_dev(exp_sb(exp)->s_dev))
 509                 /* for newer device numbers, we must use a newer fsid format */
 510                 fsid_type = FSID_ENCODE_DEV;
 511         else
 512                 fsid_type = FSID_DEV;
 513         fhp->fh_handle.fh_version = version;
 514         if (version)
 515                 fhp->fh_handle.fh_fsid_type = fsid_type;
 516 }
 517
 518 __be32
 519 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
 520            struct svc_fh *ref_fh)
 521 {
 522         /* ref_fh is a reference file handle.
 523          * if it is non-null and for the same filesystem, then we should compose
 524          * a filehandle which is of the same version, where possible.
 525          * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
 526          * Then create a 32byte filehandle using nfs_fhbase_old
 527          *
 528          */
 529
 530         struct inode * inode = d_inode(dentry);
 531         dev_t ex_dev = exp_sb(exp)->s_dev;
 532
 533         dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
 534                 MAJOR(ex_dev), MINOR(ex_dev),
 535                 (long) d_inode(exp->ex_path.dentry)->i_ino,
 536                 dentry,
 537                 (inode ? inode->i_ino : 0));
 538
 539         /* Choose filehandle version and fsid type based on
 540          * the reference filehandle (if it is in the same export)
 541          * or the export options.
 542          */
 543         set_version_and_fsid_type(fhp, exp, ref_fh);
 544
 545         if (ref_fh == fhp)
 546                 fh_put(ref_fh);
 547
 548         if (fhp->fh_locked || fhp->fh_dentry) {
 549                 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
 550                        dentry);
 551         }
 552         if (fhp->fh_maxsize < NFS_FHSIZE)
 553                 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
 554                        fhp->fh_maxsize,
 555                        dentry);
 556
 557         fhp->fh_dentry = dget(dentry); /* our internal copy */
 558         fhp->fh_export = exp_get(exp);
 559
 560         if (fhp->fh_handle.fh_version == 0xca) {
 561                 /* old style filehandle please */
 562                 memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
 563                 fhp->fh_handle.fh_size = NFS_FHSIZE;
 564                 fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
 565                 fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
 566                 fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
 567                 fhp->fh_handle.ofh_xino =
 568                         ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
 569                 fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
 570                 if (inode)
 571                         _fh_update_old(dentry, exp, &fhp->fh_handle);
 572         } else {
 573                 fhp->fh_handle.fh_size =
 574                         key_len(fhp->fh_handle.fh_fsid_type) + 4;
 575                 fhp->fh_handle.fh_auth_type = 0;
 576
 577                 mk_fsid(fhp->fh_handle.fh_fsid_type,
 578                         fhp->fh_handle.fh_fsid,
 579                         ex_dev,
 580                         d_inode(exp->ex_path.dentry)->i_ino,
 581                         exp->ex_fsid, exp->ex_uuid);
 582
 583                 if (inode)
 584                         _fh_update(fhp, exp, dentry);
 585                 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
 586                         fh_put(fhp);
 587                         return nfserr_opnotsupp;
 588                 }
 589         }
 590
 591         return 0;
 592 }
 593
 594 /*
 595  * Update file handle information after changing a dentry.
 596  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
 597  */
 598 __be32
 599 fh_update(struct svc_fh *fhp)
 600 {
 601         struct dentry *dentry;
 602
 603         if (!fhp->fh_dentry)
 604                 goto out_bad;
 605
 606         dentry = fhp->fh_dentry;
 607         if (d_really_is_negative(dentry))
 608                 goto out_negative;
 609         if (fhp->fh_handle.fh_version != 1) {
 610                 _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
 611         } else {
 612                 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
 613                         return 0;
 614
 615                 _fh_update(fhp, fhp->fh_export, dentry);
 616                 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
 617                         return nfserr_opnotsupp;
 618         }
 619         return 0;
 620 out_bad:
 621         printk(KERN_ERR "fh_update: fh not verified!\n");
 622         return nfserr_serverfault;
 623 out_negative:
 624         printk(KERN_ERR "fh_update: %pd2 still negative!\n",
 625                 dentry);
 626         return nfserr_serverfault;
 627 }
 628
 629 /*
 630  * Release a file handle.
 631  */
 632 void
 633 fh_put(struct svc_fh *fhp)
 634 {
 635         struct dentry * dentry = fhp->fh_dentry;
 636         struct svc_export * exp = fhp->fh_export;
 637         if (dentry) {
 638                 fh_unlock(fhp);
 639                 fhp->fh_dentry = NULL;
 640                 dput(dentry);
 641                 fh_clear_wcc(fhp);
 642         }
 643         fh_drop_write(fhp);
 644         if (exp) {
 645                 exp_put(exp);
 646                 fhp->fh_export = NULL;
 647         }
 648         return;
 649 }
 650
 651 /*
 652  * Shorthand for dprintk()'s
 653  */
 654 char * SVCFH_fmt(struct svc_fh *fhp)
 655 {
 656         struct knfsd_fh *fh = &fhp->fh_handle;
 657
 658         static char buf[80];
 659         sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
 660                 fh->fh_size,
 661                 fh->fh_base.fh_pad[0],
 662                 fh->fh_base.fh_pad[1],
 663                 fh->fh_base.fh_pad[2],
 664                 fh->fh_base.fh_pad[3],
 665                 fh->fh_base.fh_pad[4],
 666                 fh->fh_base.fh_pad[5]);
 667         return buf;
 668 }
 669
 670 enum fsid_source fsid_source(struct svc_fh *fhp)
 671 {
 672         if (fhp->fh_handle.fh_version != 1)
 673                 return FSIDSOURCE_DEV;
 674         switch(fhp->fh_handle.fh_fsid_type) {
 675         case FSID_DEV:
 676         case FSID_ENCODE_DEV:
 677         case FSID_MAJOR_MINOR:
 678                 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
 679                         return FSIDSOURCE_DEV;
 680                 break;
 681         case FSID_NUM:
 682                 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 683                         return FSIDSOURCE_FSID;
 684                 break;
 685         default:
 686                 break;
 687         }
 688         /* either a UUID type filehandle, or the filehandle doesn't
 689          * match the export.
 690          */
 691         if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 692                 return FSIDSOURCE_FSID;
 693         if (fhp->fh_export->ex_uuid)
 694                 return FSIDSOURCE_UUID;
 695         return FSIDSOURCE_DEV;
 696 }