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 bool nfsd_originating_port_ok(struct svc_rqst *rqstp, int flags)
  91 {
  92         if (flags & NFSEXP_INSECURE_PORT)
  93                 return true;
  94         /* We don't require gss requests to use low ports: */
  95         if (rqstp->rq_cred.cr_flavor >= RPC_AUTH_GSS)
  96                 return true;
  97         return test_bit(RQ_SECURE, &rqstp->rq_flags);
  98 }
  99
 100 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
 101                                           struct svc_export *exp)
 102 {
 103         int flags = nfsexp_flags(rqstp, exp);
 104
 105         /* Check if the request originated from a secure port. */
 106         if (!nfsd_originating_port_ok(rqstp, flags)) {
 107                 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 108                 dprintk("nfsd: request from insecure port %s!\n",
 109                         svc_print_addr(rqstp, buf, sizeof(buf)));
 110                 return nfserr_perm;
 111         }
 112
 113         /* Set user creds for this exportpoint */
 114         return nfserrno(nfsd_setuser(rqstp, exp));
 115 }
 116
 117 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
 118         struct dentry *dentry, struct svc_export *exp)
 119 {
 120         if (!(exp->ex_flags & NFSEXP_V4ROOT))
 121                 return nfs_ok;
 122         /*
 123          * v2/v3 clients have no need for the V4ROOT export--they use
 124          * the mount protocl instead; also, further V4ROOT checks may be
 125          * in v4-specific code, in which case v2/v3 clients could bypass
 126          * them.
 127          */
 128         if (!nfsd_v4client(rqstp))
 129                 return nfserr_stale;
 130         /*
 131          * We're exposing only the directories and symlinks that have to be
 132          * traversed on the way to real exports:
 133          */
 134         if (unlikely(!d_is_dir(dentry) &&
 135                      !d_is_symlink(dentry)))
 136                 return nfserr_stale;
 137         /*
 138          * A pseudoroot export gives permission to access only one
 139          * single directory; the kernel has to make another upcall
 140          * before granting access to anything else under it:
 141          */
 142         if (unlikely(dentry != exp->ex_path.dentry))
 143                 return nfserr_stale;
 144         return nfs_ok;
 145 }
 146
 147 /*
 148  * Use the given filehandle to look up the corresponding export and
 149  * dentry.  On success, the results are used to set fh_export and
 150  * fh_dentry.
 151  */
 152 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 153 {
 154         struct knfsd_fh *fh = &fhp->fh_handle;
 155         struct fid *fid = NULL, sfid;
 156         struct svc_export *exp;
 157         struct dentry *dentry;
 158         int fileid_type;
 159         int data_left = fh->fh_size/4;
 160         __be32 error;
 161
 162         error = nfserr_stale;
 163         if (rqstp->rq_vers > 2)
 164                 error = nfserr_badhandle;
 165         if (rqstp->rq_vers == 4 && fh->fh_size == 0)
 166                 return nfserr_nofilehandle;
 167
 168         if (fh->fh_version == 1) {
 169                 int len;
 170
 171                 if (--data_left < 0)
 172                         return error;
 173                 if (fh->fh_auth_type != 0)
 174                         return error;
 175                 len = key_len(fh->fh_fsid_type) / 4;
 176                 if (len == 0)
 177                         return error;
 178                 if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
 179                         /* deprecated, convert to type 3 */
 180                         len = key_len(FSID_ENCODE_DEV)/4;
 181                         fh->fh_fsid_type = FSID_ENCODE_DEV;
 182                         /*
 183                          * struct knfsd_fh uses host-endian fields, which are
 184                          * sometimes used to hold net-endian values. This
 185                          * confuses sparse, so we must use __force here to
 186                          * keep it from complaining.
 187                          */
 188                         fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
 189                                                         ntohl((__force __be32)fh->fh_fsid[1])));
 190                         fh->fh_fsid[1] = fh->fh_fsid[2];
 191                 }
 192                 data_left -= len;
 193                 if (data_left < 0)
 194                         return error;
 195                 exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
 196                 fid = (struct fid *)(fh->fh_fsid + len);
 197         } else {
 198                 __u32 tfh[2];
 199                 dev_t xdev;
 200                 ino_t xino;
 201
 202                 if (fh->fh_size != NFS_FHSIZE)
 203                         return error;
 204                 /* assume old filehandle format */
 205                 xdev = old_decode_dev(fh->ofh_xdev);
 206                 xino = u32_to_ino_t(fh->ofh_xino);
 207                 mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
 208                 exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
 209         }
 210
 211         error = nfserr_stale;
 212         if (PTR_ERR(exp) == -ENOENT)
 213                 return error;
 214
 215         if (IS_ERR(exp))
 216                 return nfserrno(PTR_ERR(exp));
 217
 218         if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
 219                 /* Elevate privileges so that the lack of 'r' or 'x'
 220                  * permission on some parent directory will
 221                  * not stop exportfs_decode_fh from being able
 222                  * to reconnect a directory into the dentry cache.
 223                  * The same problem can affect "SUBTREECHECK" exports,
 224                  * but as nfsd_acceptable depends on correct
 225                  * access control settings being in effect, we cannot
 226                  * fix that case easily.
 227                  */
 228                 struct cred *new = prepare_creds();
 229                 if (!new) {
 230                         error =  nfserrno(-ENOMEM);
 231                         goto out;
 232                 }
 233                 new->cap_effective =
 234                         cap_raise_nfsd_set(new->cap_effective,
 235                                            new->cap_permitted);
 236                 put_cred(override_creds(new));
 237                 put_cred(new);
 238         } else {
 239                 error = nfsd_setuser_and_check_port(rqstp, exp);
 240                 if (error)
 241                         goto out;
 242         }
 243
 244         /*
 245          * Look up the dentry using the NFS file handle.
 246          */
 247         error = nfserr_stale;
 248         if (rqstp->rq_vers > 2)
 249                 error = nfserr_badhandle;
 250
 251         if (fh->fh_version != 1) {
 252                 sfid.i32.ino = fh->ofh_ino;
 253                 sfid.i32.gen = fh->ofh_generation;
 254                 sfid.i32.parent_ino = fh->ofh_dirino;
 255                 fid = &sfid;
 256                 data_left = 3;
 257                 if (fh->ofh_dirino == 0)
 258                         fileid_type = FILEID_INO32_GEN;
 259                 else
 260                         fileid_type = FILEID_INO32_GEN_PARENT;
 261         } else
 262                 fileid_type = fh->fh_fileid_type;
 263
 264         if (fileid_type == FILEID_ROOT)
 265                 dentry = dget(exp->ex_path.dentry);
 266         else {
 267                 dentry = exportfs_decode_fh(exp->ex_path.mnt, fid,
 268                                 data_left, fileid_type,
 269                                 nfsd_acceptable, exp);
 270         }
 271         if (dentry == NULL)
 272                 goto out;
 273         if (IS_ERR(dentry)) {
 274                 if (PTR_ERR(dentry) != -EINVAL)
 275                         error = nfserrno(PTR_ERR(dentry));
 276                 goto out;
 277         }
 278
 279         if (d_is_dir(dentry) &&
 280                         (dentry->d_flags & DCACHE_DISCONNECTED)) {
 281                 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
 282                                 dentry);
 283         }
 284
 285         fhp->fh_dentry = dentry;
 286         fhp->fh_export = exp;
 287         return 0;
 288 out:
 289         exp_put(exp);
 290         return error;
 291 }
 292
 293 /**
 294  * fh_verify - filehandle lookup and access checking
 295  * @rqstp: pointer to current rpc request
 296  * @fhp: filehandle to be verified
 297  * @type: expected type of object pointed to by filehandle
 298  * @access: type of access needed to object
 299  *
 300  * Look up a dentry from the on-the-wire filehandle, check the client's
 301  * access to the export, and set the current task's credentials.
 302  *
 303  * Regardless of success or failure of fh_verify(), fh_put() should be
 304  * called on @fhp when the caller is finished with the filehandle.
 305  *
 306  * fh_verify() may be called multiple times on a given filehandle, for
 307  * example, when processing an NFSv4 compound.  The first call will look
 308  * up a dentry using the on-the-wire filehandle.  Subsequent calls will
 309  * skip the lookup and just perform the other checks and possibly change
 310  * the current task's credentials.
 311  *
 312  * @type specifies the type of object expected using one of the S_IF*
 313  * constants defined in include/linux/stat.h.  The caller may use zero
 314  * to indicate that it doesn't care, or a negative integer to indicate
 315  * that it expects something not of the given type.
 316  *
 317  * @access is formed from the NFSD_MAY_* constants defined in
 318  * fs/nfsd/vfs.h.
 319  */
 320 __be32
 321 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
 322 {
 323         struct svc_export *exp;
 324         struct dentry   *dentry;
 325         __be32          error;
 326
 327         dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
 328
 329         if (!fhp->fh_dentry) {
 330                 error = nfsd_set_fh_dentry(rqstp, fhp);
 331                 if (error)
 332                         goto out;
 333         }
 334         dentry = fhp->fh_dentry;
 335         exp = fhp->fh_export;
 336         /*
 337          * We still have to do all these permission checks, even when
 338          * fh_dentry is already set:
 339          *      - fh_verify may be called multiple times with different
 340          *        "access" arguments (e.g. nfsd_proc_create calls
 341          *        fh_verify(...,NFSD_MAY_EXEC) first, then later (in
 342          *        nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
 343          *      - in the NFSv4 case, the filehandle may have been filled
 344          *        in by fh_compose, and given a dentry, but further
 345          *        compound operations performed with that filehandle
 346          *        still need permissions checks.  In the worst case, a
 347          *        mountpoint crossing may have changed the export
 348          *        options, and we may now need to use a different uid
 349          *        (for example, if different id-squashing options are in
 350          *        effect on the new filesystem).
 351          */
 352         error = check_pseudo_root(rqstp, dentry, exp);
 353         if (error)
 354                 goto out;
 355
 356         error = nfsd_setuser_and_check_port(rqstp, exp);
 357         if (error)
 358                 goto out;
 359
 360         error = nfsd_mode_check(rqstp, dentry, type);
 361         if (error)
 362                 goto out;
 363
 364         /*
 365          * pseudoflavor restrictions are not enforced on NLM,
 366          * which clients virtually always use auth_sys for,
 367          * even while using RPCSEC_GSS for NFS.
 368          */
 369         if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
 370                 goto skip_pseudoflavor_check;
 371         /*
 372          * Clients may expect to be able to use auth_sys during mount,
 373          * even if they use gss for everything else; see section 2.3.2
 374          * of rfc 2623.
 375          */
 376         if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
 377                         && exp->ex_path.dentry == dentry)
 378                 goto skip_pseudoflavor_check;
 379
 380         error = check_nfsd_access(exp, rqstp);
 381         if (error)
 382                 goto out;
 383
 384 skip_pseudoflavor_check:
 385         /* Finally, check access permissions. */
 386         error = nfsd_permission(rqstp, exp, dentry, access);
 387
 388         if (error) {
 389                 dprintk("fh_verify: %pd2 permission failure, "
 390                         "acc=%x, error=%d\n",
 391                         dentry,
 392                         access, ntohl(error));
 393         }
 394 out:
 395         if (error == nfserr_stale)
 396                 nfsdstats.fh_stale++;
 397         return error;
 398 }
 399
 400
 401 /*
 402  * Compose a file handle for an NFS reply.
 403  *
 404  * Note that when first composed, the dentry may not yet have
 405  * an inode.  In this case a call to fh_update should be made
 406  * before the fh goes out on the wire ...
 407  */
 408 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
 409                 struct dentry *dentry)
 410 {
 411         if (dentry != exp->ex_path.dentry) {
 412                 struct fid *fid = (struct fid *)
 413                         (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
 414                 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
 415                 int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
 416
 417                 fhp->fh_handle.fh_fileid_type =
 418                         exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
 419                 fhp->fh_handle.fh_size += maxsize * 4;
 420         } else {
 421                 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
 422         }
 423 }
 424
 425 /*
 426  * for composing old style file handles
 427  */
 428 static inline void _fh_update_old(struct dentry *dentry,
 429                                   struct svc_export *exp,
 430                                   struct knfsd_fh *fh)
 431 {
 432         fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
 433         fh->ofh_generation = d_inode(dentry)->i_generation;
 434         if (d_is_dir(dentry) ||
 435             (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
 436                 fh->ofh_dirino = 0;
 437 }
 438
 439 static bool is_root_export(struct svc_export *exp)
 440 {
 441         return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
 442 }
 443
 444 static struct super_block *exp_sb(struct svc_export *exp)
 445 {
 446         return exp->ex_path.dentry->d_sb;
 447 }
 448
 449 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
 450 {
 451         switch (fsid_type) {
 452         case FSID_DEV:
 453                 if (!old_valid_dev(exp_sb(exp)->s_dev))
 454                         return false;
 455                 /* FALL THROUGH */
 456         case FSID_MAJOR_MINOR:
 457         case FSID_ENCODE_DEV:
 458                 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
 459         case FSID_NUM:
 460                 return exp->ex_flags & NFSEXP_FSID;
 461         case FSID_UUID8:
 462         case FSID_UUID16:
 463                 if (!is_root_export(exp))
 464                         return false;
 465                 /* fall through */
 466         case FSID_UUID4_INUM:
 467         case FSID_UUID16_INUM:
 468                 return exp->ex_uuid != NULL;
 469         }
 470         return true;
 471 }
 472
 473
 474 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
 475 {
 476         u8 version;
 477         u8 fsid_type;
 478 retry:
 479         version = 1;
 480         if (ref_fh && ref_fh->fh_export == exp) {
 481                 version = ref_fh->fh_handle.fh_version;
 482                 fsid_type = ref_fh->fh_handle.fh_fsid_type;
 483
 484                 ref_fh = NULL;
 485
 486                 switch (version) {
 487                 case 0xca:
 488                         fsid_type = FSID_DEV;
 489                         break;
 490                 case 1:
 491                         break;
 492                 default:
 493                         goto retry;
 494                 }
 495
 496                 /*
 497                  * As the fsid -> filesystem mapping was guided by
 498                  * user-space, there is no guarantee that the filesystem
 499                  * actually supports that fsid type. If it doesn't we
 500                  * loop around again without ref_fh set.
 501                  */
 502                 if (!fsid_type_ok_for_exp(fsid_type, exp))
 503                         goto retry;
 504         } else if (exp->ex_flags & NFSEXP_FSID) {
 505                 fsid_type = FSID_NUM;
 506         } else if (exp->ex_uuid) {
 507                 if (fhp->fh_maxsize >= 64) {
 508                         if (is_root_export(exp))
 509                                 fsid_type = FSID_UUID16;
 510                         else
 511                                 fsid_type = FSID_UUID16_INUM;
 512                 } else {
 513                         if (is_root_export(exp))
 514                                 fsid_type = FSID_UUID8;
 515                         else
 516                                 fsid_type = FSID_UUID4_INUM;
 517                 }
 518         } else if (!old_valid_dev(exp_sb(exp)->s_dev))
 519                 /* for newer device numbers, we must use a newer fsid format */
 520                 fsid_type = FSID_ENCODE_DEV;
 521         else
 522                 fsid_type = FSID_DEV;
 523         fhp->fh_handle.fh_version = version;
 524         if (version)
 525                 fhp->fh_handle.fh_fsid_type = fsid_type;
 526 }
 527
 528 __be32
 529 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
 530            struct svc_fh *ref_fh)
 531 {
 532         /* ref_fh is a reference file handle.
 533          * if it is non-null and for the same filesystem, then we should compose
 534          * a filehandle which is of the same version, where possible.
 535          * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
 536          * Then create a 32byte filehandle using nfs_fhbase_old
 537          *
 538          */
 539
 540         struct inode * inode = d_inode(dentry);
 541         dev_t ex_dev = exp_sb(exp)->s_dev;
 542
 543         dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
 544                 MAJOR(ex_dev), MINOR(ex_dev),
 545                 (long) d_inode(exp->ex_path.dentry)->i_ino,
 546                 dentry,
 547                 (inode ? inode->i_ino : 0));
 548
 549         /* Choose filehandle version and fsid type based on
 550          * the reference filehandle (if it is in the same export)
 551          * or the export options.
 552          */
 553         set_version_and_fsid_type(fhp, exp, ref_fh);
 554
 555         if (ref_fh == fhp)
 556                 fh_put(ref_fh);
 557
 558         if (fhp->fh_locked || fhp->fh_dentry) {
 559                 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
 560                        dentry);
 561         }
 562         if (fhp->fh_maxsize < NFS_FHSIZE)
 563                 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
 564                        fhp->fh_maxsize,
 565                        dentry);
 566
 567         fhp->fh_dentry = dget(dentry); /* our internal copy */
 568         fhp->fh_export = exp_get(exp);
 569
 570         if (fhp->fh_handle.fh_version == 0xca) {
 571                 /* old style filehandle please */
 572                 memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
 573                 fhp->fh_handle.fh_size = NFS_FHSIZE;
 574                 fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
 575                 fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
 576                 fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
 577                 fhp->fh_handle.ofh_xino =
 578                         ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
 579                 fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
 580                 if (inode)
 581                         _fh_update_old(dentry, exp, &fhp->fh_handle);
 582         } else {
 583                 fhp->fh_handle.fh_size =
 584                         key_len(fhp->fh_handle.fh_fsid_type) + 4;
 585                 fhp->fh_handle.fh_auth_type = 0;
 586
 587                 mk_fsid(fhp->fh_handle.fh_fsid_type,
 588                         fhp->fh_handle.fh_fsid,
 589                         ex_dev,
 590                         d_inode(exp->ex_path.dentry)->i_ino,
 591                         exp->ex_fsid, exp->ex_uuid);
 592
 593                 if (inode)
 594                         _fh_update(fhp, exp, dentry);
 595                 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
 596                         fh_put(fhp);
 597                         return nfserr_opnotsupp;
 598                 }
 599         }
 600
 601         return 0;
 602 }
 603
 604 /*
 605  * Update file handle information after changing a dentry.
 606  * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
 607  */
 608 __be32
 609 fh_update(struct svc_fh *fhp)
 610 {
 611         struct dentry *dentry;
 612
 613         if (!fhp->fh_dentry)
 614                 goto out_bad;
 615
 616         dentry = fhp->fh_dentry;
 617         if (d_really_is_negative(dentry))
 618                 goto out_negative;
 619         if (fhp->fh_handle.fh_version != 1) {
 620                 _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
 621         } else {
 622                 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
 623                         return 0;
 624
 625                 _fh_update(fhp, fhp->fh_export, dentry);
 626                 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
 627                         return nfserr_opnotsupp;
 628         }
 629         return 0;
 630 out_bad:
 631         printk(KERN_ERR "fh_update: fh not verified!\n");
 632         return nfserr_serverfault;
 633 out_negative:
 634         printk(KERN_ERR "fh_update: %pd2 still negative!\n",
 635                 dentry);
 636         return nfserr_serverfault;
 637 }
 638
 639 /*
 640  * Release a file handle.
 641  */
 642 void
 643 fh_put(struct svc_fh *fhp)
 644 {
 645         struct dentry * dentry = fhp->fh_dentry;
 646         struct svc_export * exp = fhp->fh_export;
 647         if (dentry) {
 648                 fh_unlock(fhp);
 649                 fhp->fh_dentry = NULL;
 650                 dput(dentry);
 651                 fh_clear_wcc(fhp);
 652         }
 653         fh_drop_write(fhp);
 654         if (exp) {
 655                 exp_put(exp);
 656                 fhp->fh_export = NULL;
 657         }
 658         return;
 659 }
 660
 661 /*
 662  * Shorthand for dprintk()'s
 663  */
 664 char * SVCFH_fmt(struct svc_fh *fhp)
 665 {
 666         struct knfsd_fh *fh = &fhp->fh_handle;
 667
 668         static char buf[80];
 669         sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
 670                 fh->fh_size,
 671                 fh->fh_base.fh_pad[0],
 672                 fh->fh_base.fh_pad[1],
 673                 fh->fh_base.fh_pad[2],
 674                 fh->fh_base.fh_pad[3],
 675                 fh->fh_base.fh_pad[4],
 676                 fh->fh_base.fh_pad[5]);
 677         return buf;
 678 }
 679
 680 enum fsid_source fsid_source(struct svc_fh *fhp)
 681 {
 682         if (fhp->fh_handle.fh_version != 1)
 683                 return FSIDSOURCE_DEV;
 684         switch(fhp->fh_handle.fh_fsid_type) {
 685         case FSID_DEV:
 686         case FSID_ENCODE_DEV:
 687         case FSID_MAJOR_MINOR:
 688                 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
 689                         return FSIDSOURCE_DEV;
 690                 break;
 691         case FSID_NUM:
 692                 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 693                         return FSIDSOURCE_FSID;
 694                 break;
 695         default:
 696                 break;
 697         }
 698         /* either a UUID type filehandle, or the filehandle doesn't
 699          * match the export.
 700          */
 701         if (fhp->fh_export->ex_flags & NFSEXP_FSID)
 702                 return FSIDSOURCE_FSID;
 703         if (fhp->fh_export->ex_uuid)
 704                 return FSIDSOURCE_UUID;
 705         return FSIDSOURCE_DEV;
 706 }