1 // SPDX-License-Identifier: GPL-2.0
3 * NFS server file handle treatment.
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
11 #include <linux/exportfs.h>
13 #include <linux/sunrpc/svcauth_gss.h>
19 #define NFSDDBG_FACILITY NFSDDBG_FH
23 * our acceptability function.
24 * if NOSUBTREECHECK, accept anything
25 * if not, require that we can walk up to exp->ex_dentry
26 * doing some checks on the 'x' bits
28 static int nfsd_acceptable(void *expv, struct dentry *dentry)
30 struct svc_export *exp = expv;
32 struct dentry *tdentry;
33 struct dentry *parent;
35 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
38 tdentry = dget(dentry);
39 while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) {
40 /* make sure parents give x permission to user */
42 parent = dget_parent(tdentry);
43 err = inode_permission(d_inode(parent), MAY_EXEC);
51 if (tdentry != exp->ex_path.dentry)
52 dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry);
53 rv = (tdentry == exp->ex_path.dentry);
58 /* Type check. The correct error return for type mismatches does not seem to be
59 * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
60 * comment in the NFSv3 spec says this is incorrect (implementation notes for
64 nfsd_mode_check(struct svc_rqst *rqstp, struct dentry *dentry,
67 umode_t mode = d_inode(dentry)->i_mode & S_IFMT;
69 if (requested == 0) /* the caller doesn't care */
71 if (mode == requested) {
72 if (mode == S_IFDIR && !d_can_lookup(dentry)) {
79 * v4 has an error more specific than err_notdir which we should
80 * return in preference to err_notdir:
82 if (rqstp->rq_vers == 4 && mode == S_IFLNK)
83 return nfserr_symlink;
84 if (requested == S_IFDIR)
91 static bool nfsd_originating_port_ok(struct svc_rqst *rqstp, int flags)
93 if (flags & NFSEXP_INSECURE_PORT)
95 /* We don't require gss requests to use low ports: */
96 if (rqstp->rq_cred.cr_flavor >= RPC_AUTH_GSS)
98 return test_bit(RQ_SECURE, &rqstp->rq_flags);
101 static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
102 struct svc_export *exp)
104 int flags = nfsexp_flags(rqstp, exp);
106 /* Check if the request originated from a secure port. */
107 if (!nfsd_originating_port_ok(rqstp, flags)) {
108 RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
109 dprintk("nfsd: request from insecure port %s!\n",
110 svc_print_addr(rqstp, buf, sizeof(buf)));
114 /* Set user creds for this exportpoint */
115 return nfserrno(nfsd_setuser(rqstp, exp));
118 static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
119 struct dentry *dentry, struct svc_export *exp)
121 if (!(exp->ex_flags & NFSEXP_V4ROOT))
124 * v2/v3 clients have no need for the V4ROOT export--they use
125 * the mount protocl instead; also, further V4ROOT checks may be
126 * in v4-specific code, in which case v2/v3 clients could bypass
129 if (!nfsd_v4client(rqstp))
132 * We're exposing only the directories and symlinks that have to be
133 * traversed on the way to real exports:
135 if (unlikely(!d_is_dir(dentry) &&
136 !d_is_symlink(dentry)))
139 * A pseudoroot export gives permission to access only one
140 * single directory; the kernel has to make another upcall
141 * before granting access to anything else under it:
143 if (unlikely(dentry != exp->ex_path.dentry))
149 * Use the given filehandle to look up the corresponding export and
150 * dentry. On success, the results are used to set fh_export and
153 static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
155 struct knfsd_fh *fh = &fhp->fh_handle;
156 struct fid *fid = NULL, sfid;
157 struct svc_export *exp;
158 struct dentry *dentry;
160 int data_left = fh->fh_size/4;
163 error = nfserr_stale;
164 if (rqstp->rq_vers > 2)
165 error = nfserr_badhandle;
166 if (rqstp->rq_vers == 4 && fh->fh_size == 0)
167 return nfserr_nofilehandle;
169 if (fh->fh_version == 1) {
174 if (fh->fh_auth_type != 0)
176 len = key_len(fh->fh_fsid_type) / 4;
179 if (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
180 /* deprecated, convert to type 3 */
181 len = key_len(FSID_ENCODE_DEV)/4;
182 fh->fh_fsid_type = FSID_ENCODE_DEV;
184 * struct knfsd_fh uses host-endian fields, which are
185 * sometimes used to hold net-endian values. This
186 * confuses sparse, so we must use __force here to
187 * keep it from complaining.
189 fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]),
190 ntohl((__force __be32)fh->fh_fsid[1])));
191 fh->fh_fsid[1] = fh->fh_fsid[2];
196 exp = rqst_exp_find(rqstp, fh->fh_fsid_type, fh->fh_fsid);
197 fid = (struct fid *)(fh->fh_fsid + len);
203 if (fh->fh_size != NFS_FHSIZE)
205 /* assume old filehandle format */
206 xdev = old_decode_dev(fh->ofh_xdev);
207 xino = u32_to_ino_t(fh->ofh_xino);
208 mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
209 exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
212 error = nfserr_stale;
214 trace_nfsd_set_fh_dentry_badexport(rqstp, fhp, PTR_ERR(exp));
216 if (PTR_ERR(exp) == -ENOENT)
219 return nfserrno(PTR_ERR(exp));
222 if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
223 /* Elevate privileges so that the lack of 'r' or 'x'
224 * permission on some parent directory will
225 * not stop exportfs_decode_fh from being able
226 * to reconnect a directory into the dentry cache.
227 * The same problem can affect "SUBTREECHECK" exports,
228 * but as nfsd_acceptable depends on correct
229 * access control settings being in effect, we cannot
230 * fix that case easily.
232 struct cred *new = prepare_creds();
234 error = nfserrno(-ENOMEM);
238 cap_raise_nfsd_set(new->cap_effective,
240 put_cred(override_creds(new));
243 error = nfsd_setuser_and_check_port(rqstp, exp);
249 * Look up the dentry using the NFS file handle.
251 error = nfserr_stale;
252 if (rqstp->rq_vers > 2)
253 error = nfserr_badhandle;
255 if (fh->fh_version != 1) {
256 sfid.i32.ino = fh->ofh_ino;
257 sfid.i32.gen = fh->ofh_generation;
258 sfid.i32.parent_ino = fh->ofh_dirino;
261 if (fh->ofh_dirino == 0)
262 fileid_type = FILEID_INO32_GEN;
264 fileid_type = FILEID_INO32_GEN_PARENT;
266 fileid_type = fh->fh_fileid_type;
268 if (fileid_type == FILEID_ROOT)
269 dentry = dget(exp->ex_path.dentry);
271 dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid,
272 data_left, fileid_type,
273 nfsd_acceptable, exp);
274 if (IS_ERR_OR_NULL(dentry)) {
275 trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp,
276 dentry ? PTR_ERR(dentry) : -ESTALE);
277 switch (PTR_ERR(dentry)) {
282 dentry = ERR_PTR(-ESTALE);
288 if (IS_ERR(dentry)) {
289 if (PTR_ERR(dentry) != -EINVAL)
290 error = nfserrno(PTR_ERR(dentry));
294 if (d_is_dir(dentry) &&
295 (dentry->d_flags & DCACHE_DISCONNECTED)) {
296 printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n",
300 fhp->fh_dentry = dentry;
301 fhp->fh_export = exp;
303 switch (rqstp->rq_vers) {
305 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR)
306 fhp->fh_no_atomic_attr = true;
309 if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC)
310 fhp->fh_no_wcc = true;
313 fhp->fh_no_wcc = true;
323 * fh_verify - filehandle lookup and access checking
324 * @rqstp: pointer to current rpc request
325 * @fhp: filehandle to be verified
326 * @type: expected type of object pointed to by filehandle
327 * @access: type of access needed to object
329 * Look up a dentry from the on-the-wire filehandle, check the client's
330 * access to the export, and set the current task's credentials.
332 * Regardless of success or failure of fh_verify(), fh_put() should be
333 * called on @fhp when the caller is finished with the filehandle.
335 * fh_verify() may be called multiple times on a given filehandle, for
336 * example, when processing an NFSv4 compound. The first call will look
337 * up a dentry using the on-the-wire filehandle. Subsequent calls will
338 * skip the lookup and just perform the other checks and possibly change
339 * the current task's credentials.
341 * @type specifies the type of object expected using one of the S_IF*
342 * constants defined in include/linux/stat.h. The caller may use zero
343 * to indicate that it doesn't care, or a negative integer to indicate
344 * that it expects something not of the given type.
346 * @access is formed from the NFSD_MAY_* constants defined in
350 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
352 struct svc_export *exp = NULL;
353 struct dentry *dentry;
356 dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));
358 if (!fhp->fh_dentry) {
359 error = nfsd_set_fh_dentry(rqstp, fhp);
363 dentry = fhp->fh_dentry;
364 exp = fhp->fh_export;
366 * We still have to do all these permission checks, even when
367 * fh_dentry is already set:
368 * - fh_verify may be called multiple times with different
369 * "access" arguments (e.g. nfsd_proc_create calls
370 * fh_verify(...,NFSD_MAY_EXEC) first, then later (in
371 * nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
372 * - in the NFSv4 case, the filehandle may have been filled
373 * in by fh_compose, and given a dentry, but further
374 * compound operations performed with that filehandle
375 * still need permissions checks. In the worst case, a
376 * mountpoint crossing may have changed the export
377 * options, and we may now need to use a different uid
378 * (for example, if different id-squashing options are in
379 * effect on the new filesystem).
381 error = check_pseudo_root(rqstp, dentry, exp);
385 error = nfsd_setuser_and_check_port(rqstp, exp);
389 error = nfsd_mode_check(rqstp, dentry, type);
394 * pseudoflavor restrictions are not enforced on NLM,
395 * which clients virtually always use auth_sys for,
396 * even while using RPCSEC_GSS for NFS.
398 if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
399 goto skip_pseudoflavor_check;
401 * Clients may expect to be able to use auth_sys during mount,
402 * even if they use gss for everything else; see section 2.3.2
405 if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
406 && exp->ex_path.dentry == dentry)
407 goto skip_pseudoflavor_check;
409 error = check_nfsd_access(exp, rqstp);
413 skip_pseudoflavor_check:
414 /* Finally, check access permissions. */
415 error = nfsd_permission(rqstp, exp, dentry, access);
418 dprintk("fh_verify: %pd2 permission failure, "
419 "acc=%x, error=%d\n",
421 access, ntohl(error));
424 if (error == nfserr_stale)
425 nfsd_stats_fh_stale_inc(exp);
431 * Compose a file handle for an NFS reply.
433 * Note that when first composed, the dentry may not yet have
434 * an inode. In this case a call to fh_update should be made
435 * before the fh goes out on the wire ...
437 static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
438 struct dentry *dentry)
440 if (dentry != exp->ex_path.dentry) {
441 struct fid *fid = (struct fid *)
442 (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1);
443 int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
444 int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);
446 fhp->fh_handle.fh_fileid_type =
447 exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
448 fhp->fh_handle.fh_size += maxsize * 4;
450 fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
455 * for composing old style file handles
457 static inline void _fh_update_old(struct dentry *dentry,
458 struct svc_export *exp,
461 fh->ofh_ino = ino_t_to_u32(d_inode(dentry)->i_ino);
462 fh->ofh_generation = d_inode(dentry)->i_generation;
463 if (d_is_dir(dentry) ||
464 (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
468 static bool is_root_export(struct svc_export *exp)
470 return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
473 static struct super_block *exp_sb(struct svc_export *exp)
475 return exp->ex_path.dentry->d_sb;
478 static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
482 if (!old_valid_dev(exp_sb(exp)->s_dev))
485 case FSID_MAJOR_MINOR:
486 case FSID_ENCODE_DEV:
487 return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
489 return exp->ex_flags & NFSEXP_FSID;
492 if (!is_root_export(exp))
495 case FSID_UUID4_INUM:
496 case FSID_UUID16_INUM:
497 return exp->ex_uuid != NULL;
503 static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
509 if (ref_fh && ref_fh->fh_export == exp) {
510 version = ref_fh->fh_handle.fh_version;
511 fsid_type = ref_fh->fh_handle.fh_fsid_type;
517 fsid_type = FSID_DEV;
526 * As the fsid -> filesystem mapping was guided by
527 * user-space, there is no guarantee that the filesystem
528 * actually supports that fsid type. If it doesn't we
529 * loop around again without ref_fh set.
531 if (!fsid_type_ok_for_exp(fsid_type, exp))
533 } else if (exp->ex_flags & NFSEXP_FSID) {
534 fsid_type = FSID_NUM;
535 } else if (exp->ex_uuid) {
536 if (fhp->fh_maxsize >= 64) {
537 if (is_root_export(exp))
538 fsid_type = FSID_UUID16;
540 fsid_type = FSID_UUID16_INUM;
542 if (is_root_export(exp))
543 fsid_type = FSID_UUID8;
545 fsid_type = FSID_UUID4_INUM;
547 } else if (!old_valid_dev(exp_sb(exp)->s_dev))
548 /* for newer device numbers, we must use a newer fsid format */
549 fsid_type = FSID_ENCODE_DEV;
551 fsid_type = FSID_DEV;
552 fhp->fh_handle.fh_version = version;
554 fhp->fh_handle.fh_fsid_type = fsid_type;
558 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
559 struct svc_fh *ref_fh)
561 /* ref_fh is a reference file handle.
562 * if it is non-null and for the same filesystem, then we should compose
563 * a filehandle which is of the same version, where possible.
564 * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
565 * Then create a 32byte filehandle using nfs_fhbase_old
569 struct inode * inode = d_inode(dentry);
570 dev_t ex_dev = exp_sb(exp)->s_dev;
572 dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n",
573 MAJOR(ex_dev), MINOR(ex_dev),
574 (long) d_inode(exp->ex_path.dentry)->i_ino,
576 (inode ? inode->i_ino : 0));
578 /* Choose filehandle version and fsid type based on
579 * the reference filehandle (if it is in the same export)
580 * or the export options.
582 set_version_and_fsid_type(fhp, exp, ref_fh);
584 /* If we have a ref_fh, then copy the fh_no_wcc setting from it. */
585 fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false;
590 if (fhp->fh_locked || fhp->fh_dentry) {
591 printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n",
594 if (fhp->fh_maxsize < NFS_FHSIZE)
595 printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n",
599 fhp->fh_dentry = dget(dentry); /* our internal copy */
600 fhp->fh_export = exp_get(exp);
602 if (fhp->fh_handle.fh_version == 0xca) {
603 /* old style filehandle please */
604 memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
605 fhp->fh_handle.fh_size = NFS_FHSIZE;
606 fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
607 fhp->fh_handle.ofh_dev = old_encode_dev(ex_dev);
608 fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
609 fhp->fh_handle.ofh_xino =
610 ino_t_to_u32(d_inode(exp->ex_path.dentry)->i_ino);
611 fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
613 _fh_update_old(dentry, exp, &fhp->fh_handle);
615 fhp->fh_handle.fh_size =
616 key_len(fhp->fh_handle.fh_fsid_type) + 4;
617 fhp->fh_handle.fh_auth_type = 0;
619 mk_fsid(fhp->fh_handle.fh_fsid_type,
620 fhp->fh_handle.fh_fsid,
622 d_inode(exp->ex_path.dentry)->i_ino,
623 exp->ex_fsid, exp->ex_uuid);
626 _fh_update(fhp, exp, dentry);
627 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) {
629 return nfserr_opnotsupp;
637 * Update file handle information after changing a dentry.
638 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
641 fh_update(struct svc_fh *fhp)
643 struct dentry *dentry;
648 dentry = fhp->fh_dentry;
649 if (d_really_is_negative(dentry))
651 if (fhp->fh_handle.fh_version != 1) {
652 _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
654 if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
657 _fh_update(fhp, fhp->fh_export, dentry);
658 if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID)
659 return nfserr_opnotsupp;
663 printk(KERN_ERR "fh_update: fh not verified!\n");
664 return nfserr_serverfault;
666 printk(KERN_ERR "fh_update: %pd2 still negative!\n",
668 return nfserr_serverfault;
672 * Release a file handle.
675 fh_put(struct svc_fh *fhp)
677 struct dentry * dentry = fhp->fh_dentry;
678 struct svc_export * exp = fhp->fh_export;
681 fhp->fh_dentry = NULL;
688 fhp->fh_export = NULL;
690 fhp->fh_no_wcc = false;
695 * Shorthand for dprintk()'s
697 char * SVCFH_fmt(struct svc_fh *fhp)
699 struct knfsd_fh *fh = &fhp->fh_handle;
702 sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
704 fh->fh_base.fh_pad[0],
705 fh->fh_base.fh_pad[1],
706 fh->fh_base.fh_pad[2],
707 fh->fh_base.fh_pad[3],
708 fh->fh_base.fh_pad[4],
709 fh->fh_base.fh_pad[5]);
713 enum fsid_source fsid_source(struct svc_fh *fhp)
715 if (fhp->fh_handle.fh_version != 1)
716 return FSIDSOURCE_DEV;
717 switch(fhp->fh_handle.fh_fsid_type) {
719 case FSID_ENCODE_DEV:
720 case FSID_MAJOR_MINOR:
721 if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV)
722 return FSIDSOURCE_DEV;
725 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
726 return FSIDSOURCE_FSID;
731 /* either a UUID type filehandle, or the filehandle doesn't
734 if (fhp->fh_export->ex_flags & NFSEXP_FSID)
735 return FSIDSOURCE_FSID;
736 if (fhp->fh_export->ex_uuid)
737 return FSIDSOURCE_UUID;
738 return FSIDSOURCE_DEV;