1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * File operations used by nfsd. Some of these have been ripped from
4  * other parts of the kernel because they weren't exported, others
5  * are partial duplicates with added or changed functionality.
6  *
7  * Note that several functions dget() the dentry upon which they want
8  * to act, most notably those that create directory entries. Response
9  * dentry's are dput()'d if necessary in the release callback.
10  * So if you notice code paths that apparently fail to dput() the
11  * dentry, don't worry--they have been taken care of.
12  *
13  * Copyright (C) 1995-1999 Olaf Kirch <okir@monad.swb.de>
14  * Zerocpy NFS support (C) 2002 Hirokazu Takahashi <taka@valinux.co.jp>
15  */
16 
17 #include <linux/fs.h>
18 #include <linux/file.h>
19 #include <linux/splice.h>
20 #include <linux/falloc.h>
21 #include <linux/fcntl.h>
22 #include <linux/namei.h>
23 #include <linux/delay.h>
24 #include <linux/fsnotify.h>
25 #include <linux/posix_acl_xattr.h>
26 #include <linux/xattr.h>
27 #include <linux/jhash.h>
28 #include <linux/ima.h>
29 #include <linux/pagemap.h>
30 #include <linux/slab.h>
31 #include <linux/uaccess.h>
32 #include <linux/exportfs.h>
33 #include <linux/writeback.h>
34 #include <linux/security.h>
35 
36 #include "xdr3.h"
37 
38 #ifdef CONFIG_NFSD_V4
39 #include "../internal.h"
40 #include "acl.h"
41 #include "idmap.h"
42 #include "xdr4.h"
43 #endif /* CONFIG_NFSD_V4 */
44 
45 #include "nfsd.h"
46 #include "vfs.h"
47 #include "filecache.h"
48 #include "trace.h"
49 
50 #define NFSDDBG_FACILITY		NFSDDBG_FILEOP
51 
52 /**
53  * nfserrno - Map Linux errnos to NFS errnos
54  * @errno: POSIX(-ish) error code to be mapped
55  *
56  * Returns the appropriate (net-endian) nfserr_* (or nfs_ok if errno is 0). If
57  * it's an error we don't expect, log it once and return nfserr_io.
58  */
59 __be32
nfserrno(int errno)60 nfserrno (int errno)
61 {
62 	static struct {
63 		__be32	nfserr;
64 		int	syserr;
65 	} nfs_errtbl[] = {
66 		{ nfs_ok, 0 },
67 		{ nfserr_perm, -EPERM },
68 		{ nfserr_noent, -ENOENT },
69 		{ nfserr_io, -EIO },
70 		{ nfserr_nxio, -ENXIO },
71 		{ nfserr_fbig, -E2BIG },
72 		{ nfserr_stale, -EBADF },
73 		{ nfserr_acces, -EACCES },
74 		{ nfserr_exist, -EEXIST },
75 		{ nfserr_xdev, -EXDEV },
76 		{ nfserr_mlink, -EMLINK },
77 		{ nfserr_nodev, -ENODEV },
78 		{ nfserr_notdir, -ENOTDIR },
79 		{ nfserr_isdir, -EISDIR },
80 		{ nfserr_inval, -EINVAL },
81 		{ nfserr_fbig, -EFBIG },
82 		{ nfserr_nospc, -ENOSPC },
83 		{ nfserr_rofs, -EROFS },
84 		{ nfserr_mlink, -EMLINK },
85 		{ nfserr_nametoolong, -ENAMETOOLONG },
86 		{ nfserr_notempty, -ENOTEMPTY },
87 		{ nfserr_dquot, -EDQUOT },
88 		{ nfserr_stale, -ESTALE },
89 		{ nfserr_jukebox, -ETIMEDOUT },
90 		{ nfserr_jukebox, -ERESTARTSYS },
91 		{ nfserr_jukebox, -EAGAIN },
92 		{ nfserr_jukebox, -EWOULDBLOCK },
93 		{ nfserr_jukebox, -ENOMEM },
94 		{ nfserr_io, -ETXTBSY },
95 		{ nfserr_notsupp, -EOPNOTSUPP },
96 		{ nfserr_toosmall, -ETOOSMALL },
97 		{ nfserr_serverfault, -ESERVERFAULT },
98 		{ nfserr_serverfault, -ENFILE },
99 		{ nfserr_io, -EREMOTEIO },
100 		{ nfserr_stale, -EOPENSTALE },
101 		{ nfserr_io, -EUCLEAN },
102 		{ nfserr_perm, -ENOKEY },
103 		{ nfserr_no_grace, -ENOGRACE},
104 	};
105 	int	i;
106 
107 	for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
108 		if (nfs_errtbl[i].syserr == errno)
109 			return nfs_errtbl[i].nfserr;
110 	}
111 	WARN_ONCE(1, "nfsd: non-standard errno: %d\n", errno);
112 	return nfserr_io;
113 }
114 
115 /*
116  * Called from nfsd_lookup and encode_dirent. Check if we have crossed
117  * a mount point.
118  * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
119  *  or nfs_ok having possibly changed *dpp and *expp
120  */
121 int
nfsd_cross_mnt(struct svc_rqst * rqstp,struct dentry ** dpp,struct svc_export ** expp)122 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
123 		        struct svc_export **expp)
124 {
125 	struct svc_export *exp = *expp, *exp2 = NULL;
126 	struct dentry *dentry = *dpp;
127 	struct path path = {.mnt = mntget(exp->ex_path.mnt),
128 			    .dentry = dget(dentry)};
129 	unsigned int follow_flags = 0;
130 	int err = 0;
131 
132 	if (exp->ex_flags & NFSEXP_CROSSMOUNT)
133 		follow_flags = LOOKUP_AUTOMOUNT;
134 
135 	err = follow_down(&path, follow_flags);
136 	if (err < 0)
137 		goto out;
138 	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
139 	    nfsd_mountpoint(dentry, exp) == 2) {
140 		/* This is only a mountpoint in some other namespace */
141 		path_put(&path);
142 		goto out;
143 	}
144 
145 	exp2 = rqst_exp_get_by_name(rqstp, &path);
146 	if (IS_ERR(exp2)) {
147 		err = PTR_ERR(exp2);
148 		/*
149 		 * We normally allow NFS clients to continue
150 		 * "underneath" a mountpoint that is not exported.
151 		 * The exception is V4ROOT, where no traversal is ever
152 		 * allowed without an explicit export of the new
153 		 * directory.
154 		 */
155 		if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
156 			err = 0;
157 		path_put(&path);
158 		goto out;
159 	}
160 	if (nfsd_v4client(rqstp) ||
161 		(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
162 		/* successfully crossed mount point */
163 		/*
164 		 * This is subtle: path.dentry is *not* on path.mnt
165 		 * at this point.  The only reason we are safe is that
166 		 * original mnt is pinned down by exp, so we should
167 		 * put path *before* putting exp
168 		 */
169 		*dpp = path.dentry;
170 		path.dentry = dentry;
171 		*expp = exp2;
172 		exp2 = exp;
173 	}
174 	path_put(&path);
175 	exp_put(exp2);
176 out:
177 	return err;
178 }
179 
follow_to_parent(struct path * path)180 static void follow_to_parent(struct path *path)
181 {
182 	struct dentry *dp;
183 
184 	while (path->dentry == path->mnt->mnt_root && follow_up(path))
185 		;
186 	dp = dget_parent(path->dentry);
187 	dput(path->dentry);
188 	path->dentry = dp;
189 }
190 
nfsd_lookup_parent(struct svc_rqst * rqstp,struct dentry * dparent,struct svc_export ** exp,struct dentry ** dentryp)191 static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
192 {
193 	struct svc_export *exp2;
194 	struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
195 			    .dentry = dget(dparent)};
196 
197 	follow_to_parent(&path);
198 
199 	exp2 = rqst_exp_parent(rqstp, &path);
200 	if (PTR_ERR(exp2) == -ENOENT) {
201 		*dentryp = dget(dparent);
202 	} else if (IS_ERR(exp2)) {
203 		path_put(&path);
204 		return PTR_ERR(exp2);
205 	} else {
206 		*dentryp = dget(path.dentry);
207 		exp_put(*exp);
208 		*exp = exp2;
209 	}
210 	path_put(&path);
211 	return 0;
212 }
213 
214 /*
215  * For nfsd purposes, we treat V4ROOT exports as though there was an
216  * export at *every* directory.
217  * We return:
218  * '1' if this dentry *must* be an export point,
219  * '2' if it might be, if there is really a mount here, and
220  * '0' if there is no chance of an export point here.
221  */
nfsd_mountpoint(struct dentry * dentry,struct svc_export * exp)222 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
223 {
224 	if (!d_inode(dentry))
225 		return 0;
226 	if (exp->ex_flags & NFSEXP_V4ROOT)
227 		return 1;
228 	if (nfsd4_is_junction(dentry))
229 		return 1;
230 	if (d_managed(dentry))
231 		/*
232 		 * Might only be a mountpoint in a different namespace,
233 		 * but we need to check.
234 		 */
235 		return 2;
236 	return 0;
237 }
238 
239 __be32
nfsd_lookup_dentry(struct svc_rqst * rqstp,struct svc_fh * fhp,const char * name,unsigned int len,struct svc_export ** exp_ret,struct dentry ** dentry_ret)240 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
241 		   const char *name, unsigned int len,
242 		   struct svc_export **exp_ret, struct dentry **dentry_ret)
243 {
244 	struct svc_export	*exp;
245 	struct dentry		*dparent;
246 	struct dentry		*dentry;
247 	int			host_err;
248 
249 	dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
250 
251 	dparent = fhp->fh_dentry;
252 	exp = exp_get(fhp->fh_export);
253 
254 	/* Lookup the name, but don't follow links */
255 	if (isdotent(name, len)) {
256 		if (len==1)
257 			dentry = dget(dparent);
258 		else if (dparent != exp->ex_path.dentry)
259 			dentry = dget_parent(dparent);
260 		else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
261 			dentry = dget(dparent); /* .. == . just like at / */
262 		else {
263 			/* checking mountpoint crossing is very different when stepping up */
264 			host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
265 			if (host_err)
266 				goto out_nfserr;
267 		}
268 	} else {
269 		dentry = lookup_one_len_unlocked(name, dparent, len);
270 		host_err = PTR_ERR(dentry);
271 		if (IS_ERR(dentry))
272 			goto out_nfserr;
273 		if (nfsd_mountpoint(dentry, exp)) {
274 			host_err = nfsd_cross_mnt(rqstp, &dentry, &exp);
275 			if (host_err) {
276 				dput(dentry);
277 				goto out_nfserr;
278 			}
279 		}
280 	}
281 	*dentry_ret = dentry;
282 	*exp_ret = exp;
283 	return 0;
284 
285 out_nfserr:
286 	exp_put(exp);
287 	return nfserrno(host_err);
288 }
289 
290 /**
291  * nfsd_lookup - look up a single path component for nfsd
292  *
293  * @rqstp:   the request context
294  * @fhp:     the file handle of the directory
295  * @name:    the component name, or %NULL to look up parent
296  * @len:     length of name to examine
297  * @resfh:   pointer to pre-initialised filehandle to hold result.
298  *
299  * Look up one component of a pathname.
300  * N.B. After this call _both_ fhp and resfh need an fh_put
301  *
302  * If the lookup would cross a mountpoint, and the mounted filesystem
303  * is exported to the client with NFSEXP_NOHIDE, then the lookup is
304  * accepted as it stands and the mounted directory is
305  * returned. Otherwise the covered directory is returned.
306  * NOTE: this mountpoint crossing is not supported properly by all
307  *   clients and is explicitly disallowed for NFSv3
308  *
309  */
310 __be32
nfsd_lookup(struct svc_rqst * rqstp,struct svc_fh * fhp,const char * name,unsigned int len,struct svc_fh * resfh)311 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
312 	    unsigned int len, struct svc_fh *resfh)
313 {
314 	struct svc_export	*exp;
315 	struct dentry		*dentry;
316 	__be32 err;
317 
318 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
319 	if (err)
320 		return err;
321 	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
322 	if (err)
323 		return err;
324 	err = check_nfsd_access(exp, rqstp);
325 	if (err)
326 		goto out;
327 	/*
328 	 * Note: we compose the file handle now, but as the
329 	 * dentry may be negative, it may need to be updated.
330 	 */
331 	err = fh_compose(resfh, exp, dentry, fhp);
332 	if (!err && d_really_is_negative(dentry))
333 		err = nfserr_noent;
334 out:
335 	dput(dentry);
336 	exp_put(exp);
337 	return err;
338 }
339 
340 /*
341  * Commit metadata changes to stable storage.
342  */
343 static int
commit_inode_metadata(struct inode * inode)344 commit_inode_metadata(struct inode *inode)
345 {
346 	const struct export_operations *export_ops = inode->i_sb->s_export_op;
347 
348 	if (export_ops->commit_metadata)
349 		return export_ops->commit_metadata(inode);
350 	return sync_inode_metadata(inode, 1);
351 }
352 
353 static int
commit_metadata(struct svc_fh * fhp)354 commit_metadata(struct svc_fh *fhp)
355 {
356 	struct inode *inode = d_inode(fhp->fh_dentry);
357 
358 	if (!EX_ISSYNC(fhp->fh_export))
359 		return 0;
360 	return commit_inode_metadata(inode);
361 }
362 
363 /*
364  * Go over the attributes and take care of the small differences between
365  * NFS semantics and what Linux expects.
366  */
367 static void
nfsd_sanitize_attrs(struct inode * inode,struct iattr * iap)368 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
369 {
370 	/* Ignore mode updates on symlinks */
371 	if (S_ISLNK(inode->i_mode))
372 		iap->ia_valid &= ~ATTR_MODE;
373 
374 	/* sanitize the mode change */
375 	if (iap->ia_valid & ATTR_MODE) {
376 		iap->ia_mode &= S_IALLUGO;
377 		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
378 	}
379 
380 	/* Revoke setuid/setgid on chown */
381 	if (!S_ISDIR(inode->i_mode) &&
382 	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
383 		iap->ia_valid |= ATTR_KILL_PRIV;
384 		if (iap->ia_valid & ATTR_MODE) {
385 			/* we're setting mode too, just clear the s*id bits */
386 			iap->ia_mode &= ~S_ISUID;
387 			if (iap->ia_mode & S_IXGRP)
388 				iap->ia_mode &= ~S_ISGID;
389 		} else {
390 			/* set ATTR_KILL_* bits and let VFS handle it */
391 			iap->ia_valid |= ATTR_KILL_SUID;
392 			iap->ia_valid |=
393 				setattr_should_drop_sgid(&nop_mnt_idmap, inode);
394 		}
395 	}
396 }
397 
398 static __be32
nfsd_get_write_access(struct svc_rqst * rqstp,struct svc_fh * fhp,struct iattr * iap)399 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
400 		struct iattr *iap)
401 {
402 	struct inode *inode = d_inode(fhp->fh_dentry);
403 
404 	if (iap->ia_size < inode->i_size) {
405 		__be32 err;
406 
407 		err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
408 				NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
409 		if (err)
410 			return err;
411 	}
412 	return nfserrno(get_write_access(inode));
413 }
414 
__nfsd_setattr(struct dentry * dentry,struct iattr * iap)415 static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
416 {
417 	int host_err;
418 
419 	if (iap->ia_valid & ATTR_SIZE) {
420 		/*
421 		 * RFC5661, Section 18.30.4:
422 		 *   Changing the size of a file with SETATTR indirectly
423 		 *   changes the time_modify and change attributes.
424 		 *
425 		 * (and similar for the older RFCs)
426 		 */
427 		struct iattr size_attr = {
428 			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
429 			.ia_size	= iap->ia_size,
430 		};
431 
432 		if (iap->ia_size < 0)
433 			return -EFBIG;
434 
435 		host_err = notify_change(&nop_mnt_idmap, dentry, &size_attr, NULL);
436 		if (host_err)
437 			return host_err;
438 		iap->ia_valid &= ~ATTR_SIZE;
439 
440 		/*
441 		 * Avoid the additional setattr call below if the only other
442 		 * attribute that the client sends is the mtime, as we update
443 		 * it as part of the size change above.
444 		 */
445 		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
446 			return 0;
447 	}
448 
449 	if (!iap->ia_valid)
450 		return 0;
451 
452 	iap->ia_valid |= ATTR_CTIME;
453 	return notify_change(&nop_mnt_idmap, dentry, iap, NULL);
454 }
455 
456 /**
457  * nfsd_setattr - Set various file attributes.
458  * @rqstp: controlling RPC transaction
459  * @fhp: filehandle of target
460  * @attr: attributes to set
461  * @check_guard: set to 1 if guardtime is a valid timestamp
462  * @guardtime: do not act if ctime.tv_sec does not match this timestamp
463  *
464  * This call may adjust the contents of @attr (in particular, this
465  * call may change the bits in the na_iattr.ia_valid field).
466  *
467  * Returns nfs_ok on success, otherwise an NFS status code is
468  * returned. Caller must release @fhp by calling fh_put in either
469  * case.
470  */
471 __be32
nfsd_setattr(struct svc_rqst * rqstp,struct svc_fh * fhp,struct nfsd_attrs * attr,int check_guard,time64_t guardtime)472 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
473 	     struct nfsd_attrs *attr,
474 	     int check_guard, time64_t guardtime)
475 {
476 	struct dentry	*dentry;
477 	struct inode	*inode;
478 	struct iattr	*iap = attr->na_iattr;
479 	int		accmode = NFSD_MAY_SATTR;
480 	umode_t		ftype = 0;
481 	__be32		err;
482 	int		host_err;
483 	bool		get_write_count;
484 	bool		size_change = (iap->ia_valid & ATTR_SIZE);
485 	int		retries;
486 
487 	if (iap->ia_valid & ATTR_SIZE) {
488 		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
489 		ftype = S_IFREG;
490 	}
491 
492 	/*
493 	 * If utimes(2) and friends are called with times not NULL, we should
494 	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
495 	 * will return EACCES, when the caller's effective UID does not match
496 	 * the owner of the file, and the caller is not privileged. In this
497 	 * situation, we should return EPERM(notify_change will return this).
498 	 */
499 	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
500 		accmode |= NFSD_MAY_OWNER_OVERRIDE;
501 		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
502 			accmode |= NFSD_MAY_WRITE;
503 	}
504 
505 	/* Callers that do fh_verify should do the fh_want_write: */
506 	get_write_count = !fhp->fh_dentry;
507 
508 	/* Get inode */
509 	err = fh_verify(rqstp, fhp, ftype, accmode);
510 	if (err)
511 		return err;
512 	if (get_write_count) {
513 		host_err = fh_want_write(fhp);
514 		if (host_err)
515 			goto out;
516 	}
517 
518 	dentry = fhp->fh_dentry;
519 	inode = d_inode(dentry);
520 
521 	nfsd_sanitize_attrs(inode, iap);
522 
523 	if (check_guard && guardtime != inode_get_ctime(inode).tv_sec)
524 		return nfserr_notsync;
525 
526 	/*
527 	 * The size case is special, it changes the file in addition to the
528 	 * attributes, and file systems don't expect it to be mixed with
529 	 * "random" attribute changes.  We thus split out the size change
530 	 * into a separate call to ->setattr, and do the rest as a separate
531 	 * setattr call.
532 	 */
533 	if (size_change) {
534 		err = nfsd_get_write_access(rqstp, fhp, iap);
535 		if (err)
536 			return err;
537 	}
538 
539 	inode_lock(inode);
540 	for (retries = 1;;) {
541 		struct iattr attrs;
542 
543 		/*
544 		 * notify_change() can alter its iattr argument, making
545 		 * @iap unsuitable for submission multiple times. Make a
546 		 * copy for every loop iteration.
547 		 */
548 		attrs = *iap;
549 		host_err = __nfsd_setattr(dentry, &attrs);
550 		if (host_err != -EAGAIN || !retries--)
551 			break;
552 		if (!nfsd_wait_for_delegreturn(rqstp, inode))
553 			break;
554 	}
555 	if (attr->na_seclabel && attr->na_seclabel->len)
556 		attr->na_labelerr = security_inode_setsecctx(dentry,
557 			attr->na_seclabel->data, attr->na_seclabel->len);
558 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
559 		attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
560 						dentry, ACL_TYPE_ACCESS,
561 						attr->na_pacl);
562 	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
563 	    !attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
564 		attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
565 						dentry, ACL_TYPE_DEFAULT,
566 						attr->na_dpacl);
567 	inode_unlock(inode);
568 	if (size_change)
569 		put_write_access(inode);
570 out:
571 	if (!host_err)
572 		host_err = commit_metadata(fhp);
573 	return nfserrno(host_err);
574 }
575 
576 #if defined(CONFIG_NFSD_V4)
577 /*
578  * NFS junction information is stored in an extended attribute.
579  */
580 #define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
581 
582 /**
583  * nfsd4_is_junction - Test if an object could be an NFS junction
584  *
585  * @dentry: object to test
586  *
587  * Returns 1 if "dentry" appears to contain NFS junction information.
588  * Otherwise 0 is returned.
589  */
nfsd4_is_junction(struct dentry * dentry)590 int nfsd4_is_junction(struct dentry *dentry)
591 {
592 	struct inode *inode = d_inode(dentry);
593 
594 	if (inode == NULL)
595 		return 0;
596 	if (inode->i_mode & S_IXUGO)
597 		return 0;
598 	if (!(inode->i_mode & S_ISVTX))
599 		return 0;
600 	if (vfs_getxattr(&nop_mnt_idmap, dentry, NFSD_JUNCTION_XATTR_NAME,
601 			 NULL, 0) <= 0)
602 		return 0;
603 	return 1;
604 }
605 
nfsd4_get_cstate(struct svc_rqst * rqstp)606 static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
607 {
608 	return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
609 }
610 
nfsd4_clone_file_range(struct svc_rqst * rqstp,struct nfsd_file * nf_src,u64 src_pos,struct nfsd_file * nf_dst,u64 dst_pos,u64 count,bool sync)611 __be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
612 		struct nfsd_file *nf_src, u64 src_pos,
613 		struct nfsd_file *nf_dst, u64 dst_pos,
614 		u64 count, bool sync)
615 {
616 	struct file *src = nf_src->nf_file;
617 	struct file *dst = nf_dst->nf_file;
618 	errseq_t since;
619 	loff_t cloned;
620 	__be32 ret = 0;
621 
622 	since = READ_ONCE(dst->f_wb_err);
623 	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
624 	if (cloned < 0) {
625 		ret = nfserrno(cloned);
626 		goto out_err;
627 	}
628 	if (count && cloned != count) {
629 		ret = nfserrno(-EINVAL);
630 		goto out_err;
631 	}
632 	if (sync) {
633 		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
634 		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
635 
636 		if (!status)
637 			status = filemap_check_wb_err(dst->f_mapping, since);
638 		if (!status)
639 			status = commit_inode_metadata(file_inode(src));
640 		if (status < 0) {
641 			struct nfsd_net *nn = net_generic(nf_dst->nf_net,
642 							  nfsd_net_id);
643 
644 			trace_nfsd_clone_file_range_err(rqstp,
645 					&nfsd4_get_cstate(rqstp)->save_fh,
646 					src_pos,
647 					&nfsd4_get_cstate(rqstp)->current_fh,
648 					dst_pos,
649 					count, status);
650 			nfsd_reset_write_verifier(nn);
651 			trace_nfsd_writeverf_reset(nn, rqstp, status);
652 			ret = nfserrno(status);
653 		}
654 	}
655 out_err:
656 	return ret;
657 }
658 
nfsd_copy_file_range(struct file * src,u64 src_pos,struct file * dst,u64 dst_pos,u64 count)659 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
660 			     u64 dst_pos, u64 count)
661 {
662 	ssize_t ret;
663 
664 	/*
665 	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
666 	 * thread and client rpc slot.  The choice of 4MB is somewhat
667 	 * arbitrary.  We might instead base this on r/wsize, or make it
668 	 * tunable, or use a time instead of a byte limit, or implement
669 	 * asynchronous copy.  In theory a client could also recognize a
670 	 * limit like this and pipeline multiple COPY requests.
671 	 */
672 	count = min_t(u64, count, 1 << 22);
673 	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
674 
675 	if (ret == -EOPNOTSUPP || ret == -EXDEV)
676 		ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,
677 					  COPY_FILE_SPLICE);
678 	return ret;
679 }
680 
nfsd4_vfs_fallocate(struct svc_rqst * rqstp,struct svc_fh * fhp,struct file * file,loff_t offset,loff_t len,int flags)681 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
682 			   struct file *file, loff_t offset, loff_t len,
683 			   int flags)
684 {
685 	int error;
686 
687 	if (!S_ISREG(file_inode(file)->i_mode))
688 		return nfserr_inval;
689 
690 	error = vfs_fallocate(file, flags, offset, len);
691 	if (!error)
692 		error = commit_metadata(fhp);
693 
694 	return nfserrno(error);
695 }
696 #endif /* defined(CONFIG_NFSD_V4) */
697 
698 /*
699  * Check server access rights to a file system object
700  */
701 struct accessmap {
702 	u32		access;
703 	int		how;
704 };
705 static struct accessmap	nfs3_regaccess[] = {
706     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
707     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
708     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
709     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
710 
711 #ifdef CONFIG_NFSD_V4
712     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
713     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
714     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
715 #endif
716 
717     {	0,			0				}
718 };
719 
720 static struct accessmap	nfs3_diraccess[] = {
721     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
722     {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
723     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
724     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
725     {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
726 
727 #ifdef CONFIG_NFSD_V4
728     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
729     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
730     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
731 #endif
732 
733     {	0,			0				}
734 };
735 
736 static struct accessmap	nfs3_anyaccess[] = {
737 	/* Some clients - Solaris 2.6 at least, make an access call
738 	 * to the server to check for access for things like /dev/null
739 	 * (which really, the server doesn't care about).  So
740 	 * We provide simple access checking for them, looking
741 	 * mainly at mode bits, and we make sure to ignore read-only
742 	 * filesystem checks
743 	 */
744     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
745     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
746     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
747     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
748 
749     {	0,			0				}
750 };
751 
752 __be32
nfsd_access(struct svc_rqst * rqstp,struct svc_fh * fhp,u32 * access,u32 * supported)753 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
754 {
755 	struct accessmap	*map;
756 	struct svc_export	*export;
757 	struct dentry		*dentry;
758 	u32			query, result = 0, sresult = 0;
759 	__be32			error;
760 
761 	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
762 	if (error)
763 		goto out;
764 
765 	export = fhp->fh_export;
766 	dentry = fhp->fh_dentry;
767 
768 	if (d_is_reg(dentry))
769 		map = nfs3_regaccess;
770 	else if (d_is_dir(dentry))
771 		map = nfs3_diraccess;
772 	else
773 		map = nfs3_anyaccess;
774 
775 
776 	query = *access;
777 	for  (; map->access; map++) {
778 		if (map->access & query) {
779 			__be32 err2;
780 
781 			sresult |= map->access;
782 
783 			err2 = nfsd_permission(rqstp, export, dentry, map->how);
784 			switch (err2) {
785 			case nfs_ok:
786 				result |= map->access;
787 				break;
788 
789 			/* the following error codes just mean the access was not allowed,
790 			 * rather than an error occurred */
791 			case nfserr_rofs:
792 			case nfserr_acces:
793 			case nfserr_perm:
794 				/* simply don't "or" in the access bit. */
795 				break;
796 			default:
797 				error = err2;
798 				goto out;
799 			}
800 		}
801 	}
802 	*access = result;
803 	if (supported)
804 		*supported = sresult;
805 
806  out:
807 	return error;
808 }
809 
nfsd_open_break_lease(struct inode * inode,int access)810 int nfsd_open_break_lease(struct inode *inode, int access)
811 {
812 	unsigned int mode;
813 
814 	if (access & NFSD_MAY_NOT_BREAK_LEASE)
815 		return 0;
816 	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
817 	return break_lease(inode, mode | O_NONBLOCK);
818 }
819 
820 /*
821  * Open an existing file or directory.
822  * The may_flags argument indicates the type of open (read/write/lock)
823  * and additional flags.
824  * N.B. After this call fhp needs an fh_put
825  */
826 static int
__nfsd_open(struct svc_rqst * rqstp,struct svc_fh * fhp,umode_t type,int may_flags,struct file ** filp)827 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
828 			int may_flags, struct file **filp)
829 {
830 	struct path	path;
831 	struct inode	*inode;
832 	struct file	*file;
833 	int		flags = O_RDONLY|O_LARGEFILE;
834 	int		host_err = -EPERM;
835 
836 	path.mnt = fhp->fh_export->ex_path.mnt;
837 	path.dentry = fhp->fh_dentry;
838 	inode = d_inode(path.dentry);
839 
840 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
841 		goto out;
842 
843 	if (!inode->i_fop)
844 		goto out;
845 
846 	host_err = nfsd_open_break_lease(inode, may_flags);
847 	if (host_err) /* NOMEM or WOULDBLOCK */
848 		goto out;
849 
850 	if (may_flags & NFSD_MAY_WRITE) {
851 		if (may_flags & NFSD_MAY_READ)
852 			flags = O_RDWR|O_LARGEFILE;
853 		else
854 			flags = O_WRONLY|O_LARGEFILE;
855 	}
856 
857 	file = dentry_open(&path, flags, current_cred());
858 	if (IS_ERR(file)) {
859 		host_err = PTR_ERR(file);
860 		goto out;
861 	}
862 
863 	host_err = ima_file_check(file, may_flags);
864 	if (host_err) {
865 		fput(file);
866 		goto out;
867 	}
868 
869 	if (may_flags & NFSD_MAY_64BIT_COOKIE)
870 		file->f_mode |= FMODE_64BITHASH;
871 	else
872 		file->f_mode |= FMODE_32BITHASH;
873 
874 	*filp = file;
875 out:
876 	return host_err;
877 }
878 
879 __be32
nfsd_open(struct svc_rqst * rqstp,struct svc_fh * fhp,umode_t type,int may_flags,struct file ** filp)880 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
881 		int may_flags, struct file **filp)
882 {
883 	__be32 err;
884 	int host_err;
885 	bool retried = false;
886 
887 	/*
888 	 * If we get here, then the client has already done an "open",
889 	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
890 	 * in case a chmod has now revoked permission.
891 	 *
892 	 * Arguably we should also allow the owner override for
893 	 * directories, but we never have and it doesn't seem to have
894 	 * caused anyone a problem.  If we were to change this, note
895 	 * also that our filldir callbacks would need a variant of
896 	 * lookup_one_len that doesn't check permissions.
897 	 */
898 	if (type == S_IFREG)
899 		may_flags |= NFSD_MAY_OWNER_OVERRIDE;
900 retry:
901 	err = fh_verify(rqstp, fhp, type, may_flags);
902 	if (!err) {
903 		host_err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
904 		if (host_err == -EOPENSTALE && !retried) {
905 			retried = true;
906 			fh_put(fhp);
907 			goto retry;
908 		}
909 		err = nfserrno(host_err);
910 	}
911 	return err;
912 }
913 
914 /**
915  * nfsd_open_verified - Open a regular file for the filecache
916  * @rqstp: RPC request
917  * @fhp: NFS filehandle of the file to open
918  * @may_flags: internal permission flags
919  * @filp: OUT: open "struct file *"
920  *
921  * Returns zero on success, or a negative errno value.
922  */
923 int
nfsd_open_verified(struct svc_rqst * rqstp,struct svc_fh * fhp,int may_flags,struct file ** filp)924 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
925 		   struct file **filp)
926 {
927 	return __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
928 }
929 
930 /*
931  * Grab and keep cached pages associated with a file in the svc_rqst
932  * so that they can be passed to the network sendmsg routines
933  * directly. They will be released after the sending has completed.
934  *
935  * Return values: Number of bytes consumed, or -EIO if there are no
936  * remaining pages in rqstp->rq_pages.
937  */
938 static int
nfsd_splice_actor(struct pipe_inode_info * pipe,struct pipe_buffer * buf,struct splice_desc * sd)939 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
940 		  struct splice_desc *sd)
941 {
942 	struct svc_rqst *rqstp = sd->u.data;
943 	struct page *page = buf->page;	// may be a compound one
944 	unsigned offset = buf->offset;
945 	struct page *last_page;
946 
947 	last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
948 	for (page += offset / PAGE_SIZE; page <= last_page; page++) {
949 		/*
950 		 * Skip page replacement when extending the contents of the
951 		 * current page.  But note that we may get two zero_pages in a
952 		 * row from shmem.
953 		 */
954 		if (page == *(rqstp->rq_next_page - 1) &&
955 		    offset_in_page(rqstp->rq_res.page_base +
956 				   rqstp->rq_res.page_len))
957 			continue;
958 		if (unlikely(!svc_rqst_replace_page(rqstp, page)))
959 			return -EIO;
960 	}
961 	if (rqstp->rq_res.page_len == 0)	// first call
962 		rqstp->rq_res.page_base = offset % PAGE_SIZE;
963 	rqstp->rq_res.page_len += sd->len;
964 	return sd->len;
965 }
966 
nfsd_direct_splice_actor(struct pipe_inode_info * pipe,struct splice_desc * sd)967 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
968 				    struct splice_desc *sd)
969 {
970 	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
971 }
972 
nfsd_eof_on_read(struct file * file,loff_t offset,ssize_t len,size_t expected)973 static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
974 		size_t expected)
975 {
976 	if (expected != 0 && len == 0)
977 		return 1;
978 	if (offset+len >= i_size_read(file_inode(file)))
979 		return 1;
980 	return 0;
981 }
982 
nfsd_finish_read(struct svc_rqst * rqstp,struct svc_fh * fhp,struct file * file,loff_t offset,unsigned long * count,u32 * eof,ssize_t host_err)983 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
984 			       struct file *file, loff_t offset,
985 			       unsigned long *count, u32 *eof, ssize_t host_err)
986 {
987 	if (host_err >= 0) {
988 		nfsd_stats_io_read_add(fhp->fh_export, host_err);
989 		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
990 		*count = host_err;
991 		fsnotify_access(file);
992 		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
993 		return 0;
994 	} else {
995 		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
996 		return nfserrno(host_err);
997 	}
998 }
999 
1000 /**
1001  * nfsd_splice_read - Perform a VFS read using a splice pipe
1002  * @rqstp: RPC transaction context
1003  * @fhp: file handle of file to be read
1004  * @file: opened struct file of file to be read
1005  * @offset: starting byte offset
1006  * @count: IN: requested number of bytes; OUT: number of bytes read
1007  * @eof: OUT: set non-zero if operation reached the end of the file
1008  *
1009  * Returns nfs_ok on success, otherwise an nfserr stat value is
1010  * returned.
1011  */
nfsd_splice_read(struct svc_rqst * rqstp,struct svc_fh * fhp,struct file * file,loff_t offset,unsigned long * count,u32 * eof)1012 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1013 			struct file *file, loff_t offset, unsigned long *count,
1014 			u32 *eof)
1015 {
1016 	struct splice_desc sd = {
1017 		.len		= 0,
1018 		.total_len	= *count,
1019 		.pos		= offset,
1020 		.u.data		= rqstp,
1021 	};
1022 	ssize_t host_err;
1023 
1024 	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
1025 	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
1026 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1027 }
1028 
1029 /**
1030  * nfsd_iter_read - Perform a VFS read using an iterator
1031  * @rqstp: RPC transaction context
1032  * @fhp: file handle of file to be read
1033  * @file: opened struct file of file to be read
1034  * @offset: starting byte offset
1035  * @count: IN: requested number of bytes; OUT: number of bytes read
1036  * @base: offset in first page of read buffer
1037  * @eof: OUT: set non-zero if operation reached the end of the file
1038  *
1039  * Some filesystems or situations cannot use nfsd_splice_read. This
1040  * function is the slightly less-performant fallback for those cases.
1041  *
1042  * Returns nfs_ok on success, otherwise an nfserr stat value is
1043  * returned.
1044  */
nfsd_iter_read(struct svc_rqst * rqstp,struct svc_fh * fhp,struct file * file,loff_t offset,unsigned long * count,unsigned int base,u32 * eof)1045 __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1046 		      struct file *file, loff_t offset, unsigned long *count,
1047 		      unsigned int base, u32 *eof)
1048 {
1049 	unsigned long v, total;
1050 	struct iov_iter iter;
1051 	loff_t ppos = offset;
1052 	struct page *page;
1053 	ssize_t host_err;
1054 
1055 	v = 0;
1056 	total = *count;
1057 	while (total) {
1058 		page = *(rqstp->rq_next_page++);
1059 		rqstp->rq_vec[v].iov_base = page_address(page) + base;
1060 		rqstp->rq_vec[v].iov_len = min_t(size_t, total, PAGE_SIZE - base);
1061 		total -= rqstp->rq_vec[v].iov_len;
1062 		++v;
1063 		base = 0;
1064 	}
1065 	WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_vec));
1066 
1067 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
1068 	iov_iter_kvec(&iter, ITER_DEST, rqstp->rq_vec, v, *count);
1069 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
1070 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1071 }
1072 
1073 /*
1074  * Gathered writes: If another process is currently writing to the file,
1075  * there's a high chance this is another nfsd (triggered by a bulk write
1076  * from a client's biod). Rather than syncing the file with each write
1077  * request, we sleep for 10 msec.
1078  *
1079  * I don't know if this roughly approximates C. Juszak's idea of
1080  * gathered writes, but it's a nice and simple solution (IMHO), and it
1081  * seems to work:-)
1082  *
1083  * Note: we do this only in the NFSv2 case, since v3 and higher have a
1084  * better tool (separate unstable writes and commits) for solving this
1085  * problem.
1086  */
wait_for_concurrent_writes(struct file * file)1087 static int wait_for_concurrent_writes(struct file *file)
1088 {
1089 	struct inode *inode = file_inode(file);
1090 	static ino_t last_ino;
1091 	static dev_t last_dev;
1092 	int err = 0;
1093 
1094 	if (atomic_read(&inode->i_writecount) > 1
1095 	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
1096 		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
1097 		msleep(10);
1098 		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
1099 	}
1100 
1101 	if (inode->i_state & I_DIRTY) {
1102 		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
1103 		err = vfs_fsync(file, 0);
1104 	}
1105 	last_ino = inode->i_ino;
1106 	last_dev = inode->i_sb->s_dev;
1107 	return err;
1108 }
1109 
1110 __be32
nfsd_vfs_write(struct svc_rqst * rqstp,struct svc_fh * fhp,struct nfsd_file * nf,loff_t offset,struct kvec * vec,int vlen,unsigned long * cnt,int stable,__be32 * verf)1111 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1112 				loff_t offset, struct kvec *vec, int vlen,
1113 				unsigned long *cnt, int stable,
1114 				__be32 *verf)
1115 {
1116 	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
1117 	struct file		*file = nf->nf_file;
1118 	struct super_block	*sb = file_inode(file)->i_sb;
1119 	struct svc_export	*exp;
1120 	struct iov_iter		iter;
1121 	errseq_t		since;
1122 	__be32			nfserr;
1123 	int			host_err;
1124 	int			use_wgather;
1125 	loff_t			pos = offset;
1126 	unsigned long		exp_op_flags = 0;
1127 	unsigned int		pflags = current->flags;
1128 	rwf_t			flags = 0;
1129 	bool			restore_flags = false;
1130 
1131 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
1132 
1133 	if (sb->s_export_op)
1134 		exp_op_flags = sb->s_export_op->flags;
1135 
1136 	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
1137 	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1138 		/*
1139 		 * We want throttling in balance_dirty_pages()
1140 		 * and shrink_inactive_list() to only consider
1141 		 * the backingdev we are writing to, so that nfs to
1142 		 * localhost doesn't cause nfsd to lock up due to all
1143 		 * the client's dirty pages or its congested queue.
1144 		 */
1145 		current->flags |= PF_LOCAL_THROTTLE;
1146 		restore_flags = true;
1147 	}
1148 
1149 	exp = fhp->fh_export;
1150 	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1151 
1152 	if (!EX_ISSYNC(exp))
1153 		stable = NFS_UNSTABLE;
1154 
1155 	if (stable && !use_wgather)
1156 		flags |= RWF_SYNC;
1157 
1158 	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
1159 	since = READ_ONCE(file->f_wb_err);
1160 	if (verf)
1161 		nfsd_copy_write_verifier(verf, nn);
1162 	file_start_write(file);
1163 	host_err = vfs_iter_write(file, &iter, &pos, flags);
1164 	file_end_write(file);
1165 	if (host_err < 0) {
1166 		nfsd_reset_write_verifier(nn);
1167 		trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1168 		goto out_nfserr;
1169 	}
1170 	*cnt = host_err;
1171 	nfsd_stats_io_write_add(exp, *cnt);
1172 	fsnotify_modify(file);
1173 	host_err = filemap_check_wb_err(file->f_mapping, since);
1174 	if (host_err < 0)
1175 		goto out_nfserr;
1176 
1177 	if (stable && use_wgather) {
1178 		host_err = wait_for_concurrent_writes(file);
1179 		if (host_err < 0) {
1180 			nfsd_reset_write_verifier(nn);
1181 			trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1182 		}
1183 	}
1184 
1185 out_nfserr:
1186 	if (host_err >= 0) {
1187 		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1188 		nfserr = nfs_ok;
1189 	} else {
1190 		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1191 		nfserr = nfserrno(host_err);
1192 	}
1193 	if (restore_flags)
1194 		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1195 	return nfserr;
1196 }
1197 
1198 /**
1199  * nfsd_read - Read data from a file
1200  * @rqstp: RPC transaction context
1201  * @fhp: file handle of file to be read
1202  * @offset: starting byte offset
1203  * @count: IN: requested number of bytes; OUT: number of bytes read
1204  * @eof: OUT: set non-zero if operation reached the end of the file
1205  *
1206  * The caller must verify that there is enough space in @rqstp.rq_res
1207  * to perform this operation.
1208  *
1209  * N.B. After this call fhp needs an fh_put
1210  *
1211  * Returns nfs_ok on success, otherwise an nfserr stat value is
1212  * returned.
1213  */
nfsd_read(struct svc_rqst * rqstp,struct svc_fh * fhp,loff_t offset,unsigned long * count,u32 * eof)1214 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1215 		 loff_t offset, unsigned long *count, u32 *eof)
1216 {
1217 	struct nfsd_file	*nf;
1218 	struct file *file;
1219 	__be32 err;
1220 
1221 	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1222 	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, &nf);
1223 	if (err)
1224 		return err;
1225 
1226 	file = nf->nf_file;
1227 	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1228 		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1229 	else
1230 		err = nfsd_iter_read(rqstp, fhp, file, offset, count, 0, eof);
1231 
1232 	nfsd_file_put(nf);
1233 	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1234 	return err;
1235 }
1236 
1237 /*
1238  * Write data to a file.
1239  * The stable flag requests synchronous writes.
1240  * N.B. After this call fhp needs an fh_put
1241  */
1242 __be32
nfsd_write(struct svc_rqst * rqstp,struct svc_fh * fhp,loff_t offset,struct kvec * vec,int vlen,unsigned long * cnt,int stable,__be32 * verf)1243 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1244 	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1245 	   __be32 *verf)
1246 {
1247 	struct nfsd_file *nf;
1248 	__be32 err;
1249 
1250 	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1251 
1252 	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1253 	if (err)
1254 		goto out;
1255 
1256 	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1257 			vlen, cnt, stable, verf);
1258 	nfsd_file_put(nf);
1259 out:
1260 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1261 	return err;
1262 }
1263 
1264 /**
1265  * nfsd_commit - Commit pending writes to stable storage
1266  * @rqstp: RPC request being processed
1267  * @fhp: NFS filehandle
1268  * @nf: target file
1269  * @offset: raw offset from beginning of file
1270  * @count: raw count of bytes to sync
1271  * @verf: filled in with the server's current write verifier
1272  *
1273  * Note: we guarantee that data that lies within the range specified
1274  * by the 'offset' and 'count' parameters will be synced. The server
1275  * is permitted to sync data that lies outside this range at the
1276  * same time.
1277  *
1278  * Unfortunately we cannot lock the file to make sure we return full WCC
1279  * data to the client, as locking happens lower down in the filesystem.
1280  *
1281  * Return values:
1282  *   An nfsstat value in network byte order.
1283  */
1284 __be32
nfsd_commit(struct svc_rqst * rqstp,struct svc_fh * fhp,struct nfsd_file * nf,u64 offset,u32 count,__be32 * verf)1285 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1286 	    u64 offset, u32 count, __be32 *verf)
1287 {
1288 	__be32			err = nfs_ok;
1289 	u64			maxbytes;
1290 	loff_t			start, end;
1291 	struct nfsd_net		*nn;
1292 
1293 	/*
1294 	 * Convert the client-provided (offset, count) range to a
1295 	 * (start, end) range. If the client-provided range falls
1296 	 * outside the maximum file size of the underlying FS,
1297 	 * clamp the sync range appropriately.
1298 	 */
1299 	start = 0;
1300 	end = LLONG_MAX;
1301 	maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
1302 	if (offset < maxbytes) {
1303 		start = offset;
1304 		if (count && (offset + count - 1 < maxbytes))
1305 			end = offset + count - 1;
1306 	}
1307 
1308 	nn = net_generic(nf->nf_net, nfsd_net_id);
1309 	if (EX_ISSYNC(fhp->fh_export)) {
1310 		errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
1311 		int err2;
1312 
1313 		err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
1314 		switch (err2) {
1315 		case 0:
1316 			nfsd_copy_write_verifier(verf, nn);
1317 			err2 = filemap_check_wb_err(nf->nf_file->f_mapping,
1318 						    since);
1319 			err = nfserrno(err2);
1320 			break;
1321 		case -EINVAL:
1322 			err = nfserr_notsupp;
1323 			break;
1324 		default:
1325 			nfsd_reset_write_verifier(nn);
1326 			trace_nfsd_writeverf_reset(nn, rqstp, err2);
1327 			err = nfserrno(err2);
1328 		}
1329 	} else
1330 		nfsd_copy_write_verifier(verf, nn);
1331 
1332 	return err;
1333 }
1334 
1335 /**
1336  * nfsd_create_setattr - Set a created file's attributes
1337  * @rqstp: RPC transaction being executed
1338  * @fhp: NFS filehandle of parent directory
1339  * @resfhp: NFS filehandle of new object
1340  * @attrs: requested attributes of new object
1341  *
1342  * Returns nfs_ok on success, or an nfsstat in network byte order.
1343  */
1344 __be32
nfsd_create_setattr(struct svc_rqst * rqstp,struct svc_fh * fhp,struct svc_fh * resfhp,struct nfsd_attrs * attrs)1345 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
1346 		    struct svc_fh *resfhp, struct nfsd_attrs *attrs)
1347 {
1348 	struct iattr *iap = attrs->na_iattr;
1349 	__be32 status;
1350 
1351 	/*
1352 	 * Mode has already been set by file creation.
1353 	 */
1354 	iap->ia_valid &= ~ATTR_MODE;
1355 
1356 	/*
1357 	 * Setting uid/gid works only for root.  Irix appears to
1358 	 * send along the gid on create when it tries to implement
1359 	 * setgid directories via NFS:
1360 	 */
1361 	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1362 		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1363 
1364 	/*
1365 	 * Callers expect new file metadata to be committed even
1366 	 * if the attributes have not changed.
1367 	 */
1368 	if (iap->ia_valid)
1369 		status = nfsd_setattr(rqstp, resfhp, attrs, 0, (time64_t)0);
1370 	else
1371 		status = nfserrno(commit_metadata(resfhp));
1372 
1373 	/*
1374 	 * Transactional filesystems had a chance to commit changes
1375 	 * for both parent and child simultaneously making the
1376 	 * following commit_metadata a noop in many cases.
1377 	 */
1378 	if (!status)
1379 		status = nfserrno(commit_metadata(fhp));
1380 
1381 	/*
1382 	 * Update the new filehandle to pick up the new attributes.
1383 	 */
1384 	if (!status)
1385 		status = fh_update(resfhp);
1386 
1387 	return status;
1388 }
1389 
1390 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1391  * setting size to 0 may fail for some specific file systems by the permission
1392  * checking which requires WRITE permission but the mode is 000.
1393  * we ignore the resizing(to 0) on the just new created file, since the size is
1394  * 0 after file created.
1395  *
1396  * call this only after vfs_create() is called.
1397  * */
1398 static void
nfsd_check_ignore_resizing(struct iattr * iap)1399 nfsd_check_ignore_resizing(struct iattr *iap)
1400 {
1401 	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1402 		iap->ia_valid &= ~ATTR_SIZE;
1403 }
1404 
1405 /* The parent directory should already be locked: */
1406 __be32
nfsd_create_locked(struct svc_rqst * rqstp,struct svc_fh * fhp,struct nfsd_attrs * attrs,int type,dev_t rdev,struct svc_fh * resfhp)1407 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1408 		   struct nfsd_attrs *attrs,
1409 		   int type, dev_t rdev, struct svc_fh *resfhp)
1410 {
1411 	struct dentry	*dentry, *dchild;
1412 	struct inode	*dirp;
1413 	struct iattr	*iap = attrs->na_iattr;
1414 	__be32		err;
1415 	int		host_err;
1416 
1417 	dentry = fhp->fh_dentry;
1418 	dirp = d_inode(dentry);
1419 
1420 	dchild = dget(resfhp->fh_dentry);
1421 	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1422 	if (err)
1423 		goto out;
1424 
1425 	if (!(iap->ia_valid & ATTR_MODE))
1426 		iap->ia_mode = 0;
1427 	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1428 
1429 	if (!IS_POSIXACL(dirp))
1430 		iap->ia_mode &= ~current_umask();
1431 
1432 	err = 0;
1433 	switch (type) {
1434 	case S_IFREG:
1435 		host_err = vfs_create(&nop_mnt_idmap, dirp, dchild,
1436 				      iap->ia_mode, true);
1437 		if (!host_err)
1438 			nfsd_check_ignore_resizing(iap);
1439 		break;
1440 	case S_IFDIR:
1441 		host_err = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode);
1442 		if (!host_err && unlikely(d_unhashed(dchild))) {
1443 			struct dentry *d;
1444 			d = lookup_one_len(dchild->d_name.name,
1445 					   dchild->d_parent,
1446 					   dchild->d_name.len);
1447 			if (IS_ERR(d)) {
1448 				host_err = PTR_ERR(d);
1449 				break;
1450 			}
1451 			if (unlikely(d_is_negative(d))) {
1452 				dput(d);
1453 				err = nfserr_serverfault;
1454 				goto out;
1455 			}
1456 			dput(resfhp->fh_dentry);
1457 			resfhp->fh_dentry = dget(d);
1458 			err = fh_update(resfhp);
1459 			dput(dchild);
1460 			dchild = d;
1461 			if (err)
1462 				goto out;
1463 		}
1464 		break;
1465 	case S_IFCHR:
1466 	case S_IFBLK:
1467 	case S_IFIFO:
1468 	case S_IFSOCK:
1469 		host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
1470 				     iap->ia_mode, rdev);
1471 		break;
1472 	default:
1473 		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1474 		       type);
1475 		host_err = -EINVAL;
1476 	}
1477 	if (host_err < 0)
1478 		goto out_nfserr;
1479 
1480 	err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1481 
1482 out:
1483 	dput(dchild);
1484 	return err;
1485 
1486 out_nfserr:
1487 	err = nfserrno(host_err);
1488 	goto out;
1489 }
1490 
1491 /*
1492  * Create a filesystem object (regular, directory, special).
1493  * Note that the parent directory is left locked.
1494  *
1495  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1496  */
1497 __be32
nfsd_create(struct svc_rqst * rqstp,struct svc_fh * fhp,char * fname,int flen,struct nfsd_attrs * attrs,int type,dev_t rdev,struct svc_fh * resfhp)1498 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1499 	    char *fname, int flen, struct nfsd_attrs *attrs,
1500 	    int type, dev_t rdev, struct svc_fh *resfhp)
1501 {
1502 	struct dentry	*dentry, *dchild = NULL;
1503 	__be32		err;
1504 	int		host_err;
1505 
1506 	if (isdotent(fname, flen))
1507 		return nfserr_exist;
1508 
1509 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1510 	if (err)
1511 		return err;
1512 
1513 	dentry = fhp->fh_dentry;
1514 
1515 	host_err = fh_want_write(fhp);
1516 	if (host_err)
1517 		return nfserrno(host_err);
1518 
1519 	inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
1520 	dchild = lookup_one_len(fname, dentry, flen);
1521 	host_err = PTR_ERR(dchild);
1522 	if (IS_ERR(dchild)) {
1523 		err = nfserrno(host_err);
1524 		goto out_unlock;
1525 	}
1526 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1527 	/*
1528 	 * We unconditionally drop our ref to dchild as fh_compose will have
1529 	 * already grabbed its own ref for it.
1530 	 */
1531 	dput(dchild);
1532 	if (err)
1533 		goto out_unlock;
1534 	err = fh_fill_pre_attrs(fhp);
1535 	if (err != nfs_ok)
1536 		goto out_unlock;
1537 	err = nfsd_create_locked(rqstp, fhp, attrs, type, rdev, resfhp);
1538 	fh_fill_post_attrs(fhp);
1539 out_unlock:
1540 	inode_unlock(dentry->d_inode);
1541 	return err;
1542 }
1543 
1544 /*
1545  * Read a symlink. On entry, *lenp must contain the maximum path length that
1546  * fits into the buffer. On return, it contains the true length.
1547  * N.B. After this call fhp needs an fh_put
1548  */
1549 __be32
nfsd_readlink(struct svc_rqst * rqstp,struct svc_fh * fhp,char * buf,int * lenp)1550 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1551 {
1552 	__be32		err;
1553 	const char *link;
1554 	struct path path;
1555 	DEFINE_DELAYED_CALL(done);
1556 	int len;
1557 
1558 	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1559 	if (unlikely(err))
1560 		return err;
1561 
1562 	path.mnt = fhp->fh_export->ex_path.mnt;
1563 	path.dentry = fhp->fh_dentry;
1564 
1565 	if (unlikely(!d_is_symlink(path.dentry)))
1566 		return nfserr_inval;
1567 
1568 	touch_atime(&path);
1569 
1570 	link = vfs_get_link(path.dentry, &done);
1571 	if (IS_ERR(link))
1572 		return nfserrno(PTR_ERR(link));
1573 
1574 	len = strlen(link);
1575 	if (len < *lenp)
1576 		*lenp = len;
1577 	memcpy(buf, link, *lenp);
1578 	do_delayed_call(&done);
1579 	return 0;
1580 }
1581 
1582 /**
1583  * nfsd_symlink - Create a symlink and look up its inode
1584  * @rqstp: RPC transaction being executed
1585  * @fhp: NFS filehandle of parent directory
1586  * @fname: filename of the new symlink
1587  * @flen: length of @fname
1588  * @path: content of the new symlink (NUL-terminated)
1589  * @attrs: requested attributes of new object
1590  * @resfhp: NFS filehandle of new object
1591  *
1592  * N.B. After this call _both_ fhp and resfhp need an fh_put
1593  *
1594  * Returns nfs_ok on success, or an nfsstat in network byte order.
1595  */
1596 __be32
nfsd_symlink(struct svc_rqst * rqstp,struct svc_fh * fhp,char * fname,int flen,char * path,struct nfsd_attrs * attrs,struct svc_fh * resfhp)1597 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1598 	     char *fname, int flen,
1599 	     char *path, struct nfsd_attrs *attrs,
1600 	     struct svc_fh *resfhp)
1601 {
1602 	struct dentry	*dentry, *dnew;
1603 	__be32		err, cerr;
1604 	int		host_err;
1605 
1606 	err = nfserr_noent;
1607 	if (!flen || path[0] == '\0')
1608 		goto out;
1609 	err = nfserr_exist;
1610 	if (isdotent(fname, flen))
1611 		goto out;
1612 
1613 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1614 	if (err)
1615 		goto out;
1616 
1617 	host_err = fh_want_write(fhp);
1618 	if (host_err) {
1619 		err = nfserrno(host_err);
1620 		goto out;
1621 	}
1622 
1623 	dentry = fhp->fh_dentry;
1624 	inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
1625 	dnew = lookup_one_len(fname, dentry, flen);
1626 	if (IS_ERR(dnew)) {
1627 		err = nfserrno(PTR_ERR(dnew));
1628 		inode_unlock(dentry->d_inode);
1629 		goto out_drop_write;
1630 	}
1631 	err = fh_fill_pre_attrs(fhp);
1632 	if (err != nfs_ok)
1633 		goto out_unlock;
1634 	host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path);
1635 	err = nfserrno(host_err);
1636 	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1637 	if (!err)
1638 		nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1639 	fh_fill_post_attrs(fhp);
1640 out_unlock:
1641 	inode_unlock(dentry->d_inode);
1642 	if (!err)
1643 		err = nfserrno(commit_metadata(fhp));
1644 	dput(dnew);
1645 	if (err==0) err = cerr;
1646 out_drop_write:
1647 	fh_drop_write(fhp);
1648 out:
1649 	return err;
1650 }
1651 
1652 /*
1653  * Create a hardlink
1654  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1655  */
1656 __be32
nfsd_link(struct svc_rqst * rqstp,struct svc_fh * ffhp,char * name,int len,struct svc_fh * tfhp)1657 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1658 				char *name, int len, struct svc_fh *tfhp)
1659 {
1660 	struct dentry	*ddir, *dnew, *dold;
1661 	struct inode	*dirp;
1662 	__be32		err;
1663 	int		host_err;
1664 
1665 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1666 	if (err)
1667 		goto out;
1668 	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1669 	if (err)
1670 		goto out;
1671 	err = nfserr_isdir;
1672 	if (d_is_dir(tfhp->fh_dentry))
1673 		goto out;
1674 	err = nfserr_perm;
1675 	if (!len)
1676 		goto out;
1677 	err = nfserr_exist;
1678 	if (isdotent(name, len))
1679 		goto out;
1680 
1681 	host_err = fh_want_write(tfhp);
1682 	if (host_err) {
1683 		err = nfserrno(host_err);
1684 		goto out;
1685 	}
1686 
1687 	ddir = ffhp->fh_dentry;
1688 	dirp = d_inode(ddir);
1689 	inode_lock_nested(dirp, I_MUTEX_PARENT);
1690 
1691 	dnew = lookup_one_len(name, ddir, len);
1692 	if (IS_ERR(dnew)) {
1693 		err = nfserrno(PTR_ERR(dnew));
1694 		goto out_unlock;
1695 	}
1696 
1697 	dold = tfhp->fh_dentry;
1698 
1699 	err = nfserr_noent;
1700 	if (d_really_is_negative(dold))
1701 		goto out_dput;
1702 	err = fh_fill_pre_attrs(ffhp);
1703 	if (err != nfs_ok)
1704 		goto out_dput;
1705 	host_err = vfs_link(dold, &nop_mnt_idmap, dirp, dnew, NULL);
1706 	fh_fill_post_attrs(ffhp);
1707 	inode_unlock(dirp);
1708 	if (!host_err) {
1709 		err = nfserrno(commit_metadata(ffhp));
1710 		if (!err)
1711 			err = nfserrno(commit_metadata(tfhp));
1712 	} else {
1713 		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1714 			err = nfserr_acces;
1715 		else
1716 			err = nfserrno(host_err);
1717 	}
1718 	dput(dnew);
1719 out_drop_write:
1720 	fh_drop_write(tfhp);
1721 out:
1722 	return err;
1723 
1724 out_dput:
1725 	dput(dnew);
1726 out_unlock:
1727 	inode_unlock(dirp);
1728 	goto out_drop_write;
1729 }
1730 
1731 static void
nfsd_close_cached_files(struct dentry * dentry)1732 nfsd_close_cached_files(struct dentry *dentry)
1733 {
1734 	struct inode *inode = d_inode(dentry);
1735 
1736 	if (inode && S_ISREG(inode->i_mode))
1737 		nfsd_file_close_inode_sync(inode);
1738 }
1739 
1740 static bool
nfsd_has_cached_files(struct dentry * dentry)1741 nfsd_has_cached_files(struct dentry *dentry)
1742 {
1743 	bool		ret = false;
1744 	struct inode *inode = d_inode(dentry);
1745 
1746 	if (inode && S_ISREG(inode->i_mode))
1747 		ret = nfsd_file_is_cached(inode);
1748 	return ret;
1749 }
1750 
1751 /*
1752  * Rename a file
1753  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1754  */
1755 __be32
nfsd_rename(struct svc_rqst * rqstp,struct svc_fh * ffhp,char * fname,int flen,struct svc_fh * tfhp,char * tname,int tlen)1756 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1757 			    struct svc_fh *tfhp, char *tname, int tlen)
1758 {
1759 	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1760 	struct inode	*fdir, *tdir;
1761 	__be32		err;
1762 	int		host_err;
1763 	bool		close_cached = false;
1764 
1765 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1766 	if (err)
1767 		goto out;
1768 	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1769 	if (err)
1770 		goto out;
1771 
1772 	fdentry = ffhp->fh_dentry;
1773 	fdir = d_inode(fdentry);
1774 
1775 	tdentry = tfhp->fh_dentry;
1776 	tdir = d_inode(tdentry);
1777 
1778 	err = nfserr_perm;
1779 	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1780 		goto out;
1781 
1782 	err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev;
1783 	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1784 		goto out;
1785 	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1786 		goto out;
1787 
1788 retry:
1789 	host_err = fh_want_write(ffhp);
1790 	if (host_err) {
1791 		err = nfserrno(host_err);
1792 		goto out;
1793 	}
1794 
1795 	trap = lock_rename(tdentry, fdentry);
1796 	err = fh_fill_pre_attrs(ffhp);
1797 	if (err != nfs_ok)
1798 		goto out_unlock;
1799 	err = fh_fill_pre_attrs(tfhp);
1800 	if (err != nfs_ok)
1801 		goto out_unlock;
1802 
1803 	odentry = lookup_one_len(fname, fdentry, flen);
1804 	host_err = PTR_ERR(odentry);
1805 	if (IS_ERR(odentry))
1806 		goto out_nfserr;
1807 
1808 	host_err = -ENOENT;
1809 	if (d_really_is_negative(odentry))
1810 		goto out_dput_old;
1811 	host_err = -EINVAL;
1812 	if (odentry == trap)
1813 		goto out_dput_old;
1814 
1815 	ndentry = lookup_one_len(tname, tdentry, tlen);
1816 	host_err = PTR_ERR(ndentry);
1817 	if (IS_ERR(ndentry))
1818 		goto out_dput_old;
1819 	host_err = -ENOTEMPTY;
1820 	if (ndentry == trap)
1821 		goto out_dput_new;
1822 
1823 	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1824 	    nfsd_has_cached_files(ndentry)) {
1825 		close_cached = true;
1826 		goto out_dput_old;
1827 	} else {
1828 		struct renamedata rd = {
1829 			.old_mnt_idmap	= &nop_mnt_idmap,
1830 			.old_dir	= fdir,
1831 			.old_dentry	= odentry,
1832 			.new_mnt_idmap	= &nop_mnt_idmap,
1833 			.new_dir	= tdir,
1834 			.new_dentry	= ndentry,
1835 		};
1836 		int retries;
1837 
1838 		for (retries = 1;;) {
1839 			host_err = vfs_rename(&rd);
1840 			if (host_err != -EAGAIN || !retries--)
1841 				break;
1842 			if (!nfsd_wait_for_delegreturn(rqstp, d_inode(odentry)))
1843 				break;
1844 		}
1845 		if (!host_err) {
1846 			host_err = commit_metadata(tfhp);
1847 			if (!host_err)
1848 				host_err = commit_metadata(ffhp);
1849 		}
1850 	}
1851  out_dput_new:
1852 	dput(ndentry);
1853  out_dput_old:
1854 	dput(odentry);
1855  out_nfserr:
1856 	err = nfserrno(host_err);
1857 
1858 	if (!close_cached) {
1859 		fh_fill_post_attrs(ffhp);
1860 		fh_fill_post_attrs(tfhp);
1861 	}
1862 out_unlock:
1863 	unlock_rename(tdentry, fdentry);
1864 	fh_drop_write(ffhp);
1865 
1866 	/*
1867 	 * If the target dentry has cached open files, then we need to try to
1868 	 * close them prior to doing the rename. Flushing delayed fput
1869 	 * shouldn't be done with locks held however, so we delay it until this
1870 	 * point and then reattempt the whole shebang.
1871 	 */
1872 	if (close_cached) {
1873 		close_cached = false;
1874 		nfsd_close_cached_files(ndentry);
1875 		dput(ndentry);
1876 		goto retry;
1877 	}
1878 out:
1879 	return err;
1880 }
1881 
1882 /*
1883  * Unlink a file or directory
1884  * N.B. After this call fhp needs an fh_put
1885  */
1886 __be32
nfsd_unlink(struct svc_rqst * rqstp,struct svc_fh * fhp,int type,char * fname,int flen)1887 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1888 				char *fname, int flen)
1889 {
1890 	struct dentry	*dentry, *rdentry;
1891 	struct inode	*dirp;
1892 	struct inode	*rinode;
1893 	__be32		err;
1894 	int		host_err;
1895 
1896 	err = nfserr_acces;
1897 	if (!flen || isdotent(fname, flen))
1898 		goto out;
1899 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1900 	if (err)
1901 		goto out;
1902 
1903 	host_err = fh_want_write(fhp);
1904 	if (host_err)
1905 		goto out_nfserr;
1906 
1907 	dentry = fhp->fh_dentry;
1908 	dirp = d_inode(dentry);
1909 	inode_lock_nested(dirp, I_MUTEX_PARENT);
1910 
1911 	rdentry = lookup_one_len(fname, dentry, flen);
1912 	host_err = PTR_ERR(rdentry);
1913 	if (IS_ERR(rdentry))
1914 		goto out_unlock;
1915 
1916 	if (d_really_is_negative(rdentry)) {
1917 		dput(rdentry);
1918 		host_err = -ENOENT;
1919 		goto out_unlock;
1920 	}
1921 	rinode = d_inode(rdentry);
1922 	err = fh_fill_pre_attrs(fhp);
1923 	if (err != nfs_ok)
1924 		goto out_unlock;
1925 
1926 	ihold(rinode);
1927 	if (!type)
1928 		type = d_inode(rdentry)->i_mode & S_IFMT;
1929 
1930 	if (type != S_IFDIR) {
1931 		int retries;
1932 
1933 		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1934 			nfsd_close_cached_files(rdentry);
1935 
1936 		for (retries = 1;;) {
1937 			host_err = vfs_unlink(&nop_mnt_idmap, dirp, rdentry, NULL);
1938 			if (host_err != -EAGAIN || !retries--)
1939 				break;
1940 			if (!nfsd_wait_for_delegreturn(rqstp, rinode))
1941 				break;
1942 		}
1943 	} else {
1944 		host_err = vfs_rmdir(&nop_mnt_idmap, dirp, rdentry);
1945 	}
1946 	fh_fill_post_attrs(fhp);
1947 
1948 	inode_unlock(dirp);
1949 	if (!host_err)
1950 		host_err = commit_metadata(fhp);
1951 	dput(rdentry);
1952 	iput(rinode);    /* truncate the inode here */
1953 
1954 out_drop_write:
1955 	fh_drop_write(fhp);
1956 out_nfserr:
1957 	if (host_err == -EBUSY) {
1958 		/* name is mounted-on. There is no perfect
1959 		 * error status.
1960 		 */
1961 		if (nfsd_v4client(rqstp))
1962 			err = nfserr_file_open;
1963 		else
1964 			err = nfserr_acces;
1965 	} else {
1966 		err = nfserrno(host_err);
1967 	}
1968 out:
1969 	return err;
1970 out_unlock:
1971 	inode_unlock(dirp);
1972 	goto out_drop_write;
1973 }
1974 
1975 /*
1976  * We do this buffering because we must not call back into the file
1977  * system's ->lookup() method from the filldir callback. That may well
1978  * deadlock a number of file systems.
1979  *
1980  * This is based heavily on the implementation of same in XFS.
1981  */
1982 struct buffered_dirent {
1983 	u64		ino;
1984 	loff_t		offset;
1985 	int		namlen;
1986 	unsigned int	d_type;
1987 	char		name[];
1988 };
1989 
1990 struct readdir_data {
1991 	struct dir_context ctx;
1992 	char		*dirent;
1993 	size_t		used;
1994 	int		full;
1995 };
1996 
nfsd_buffered_filldir(struct dir_context * ctx,const char * name,int namlen,loff_t offset,u64 ino,unsigned int d_type)1997 static bool nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1998 				 int namlen, loff_t offset, u64 ino,
1999 				 unsigned int d_type)
2000 {
2001 	struct readdir_data *buf =
2002 		container_of(ctx, struct readdir_data, ctx);
2003 	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
2004 	unsigned int reclen;
2005 
2006 	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
2007 	if (buf->used + reclen > PAGE_SIZE) {
2008 		buf->full = 1;
2009 		return false;
2010 	}
2011 
2012 	de->namlen = namlen;
2013 	de->offset = offset;
2014 	de->ino = ino;
2015 	de->d_type = d_type;
2016 	memcpy(de->name, name, namlen);
2017 	buf->used += reclen;
2018 
2019 	return true;
2020 }
2021 
nfsd_buffered_readdir(struct file * file,struct svc_fh * fhp,nfsd_filldir_t func,struct readdir_cd * cdp,loff_t * offsetp)2022 static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
2023 				    nfsd_filldir_t func, struct readdir_cd *cdp,
2024 				    loff_t *offsetp)
2025 {
2026 	struct buffered_dirent *de;
2027 	int host_err;
2028 	int size;
2029 	loff_t offset;
2030 	struct readdir_data buf = {
2031 		.ctx.actor = nfsd_buffered_filldir,
2032 		.dirent = (void *)__get_free_page(GFP_KERNEL)
2033 	};
2034 
2035 	if (!buf.dirent)
2036 		return nfserrno(-ENOMEM);
2037 
2038 	offset = *offsetp;
2039 
2040 	while (1) {
2041 		unsigned int reclen;
2042 
2043 		cdp->err = nfserr_eof; /* will be cleared on successful read */
2044 		buf.used = 0;
2045 		buf.full = 0;
2046 
2047 		host_err = iterate_dir(file, &buf.ctx);
2048 		if (buf.full)
2049 			host_err = 0;
2050 
2051 		if (host_err < 0)
2052 			break;
2053 
2054 		size = buf.used;
2055 
2056 		if (!size)
2057 			break;
2058 
2059 		de = (struct buffered_dirent *)buf.dirent;
2060 		while (size > 0) {
2061 			offset = de->offset;
2062 
2063 			if (func(cdp, de->name, de->namlen, de->offset,
2064 				 de->ino, de->d_type))
2065 				break;
2066 
2067 			if (cdp->err != nfs_ok)
2068 				break;
2069 
2070 			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
2071 
2072 			reclen = ALIGN(sizeof(*de) + de->namlen,
2073 				       sizeof(u64));
2074 			size -= reclen;
2075 			de = (struct buffered_dirent *)((char *)de + reclen);
2076 		}
2077 		if (size > 0) /* We bailed out early */
2078 			break;
2079 
2080 		offset = vfs_llseek(file, 0, SEEK_CUR);
2081 	}
2082 
2083 	free_page((unsigned long)(buf.dirent));
2084 
2085 	if (host_err)
2086 		return nfserrno(host_err);
2087 
2088 	*offsetp = offset;
2089 	return cdp->err;
2090 }
2091 
2092 /*
2093  * Read entries from a directory.
2094  * The  NFSv3/4 verifier we ignore for now.
2095  */
2096 __be32
nfsd_readdir(struct svc_rqst * rqstp,struct svc_fh * fhp,loff_t * offsetp,struct readdir_cd * cdp,nfsd_filldir_t func)2097 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2098 	     struct readdir_cd *cdp, nfsd_filldir_t func)
2099 {
2100 	__be32		err;
2101 	struct file	*file;
2102 	loff_t		offset = *offsetp;
2103 	int             may_flags = NFSD_MAY_READ;
2104 
2105 	/* NFSv2 only supports 32 bit cookies */
2106 	if (rqstp->rq_vers > 2)
2107 		may_flags |= NFSD_MAY_64BIT_COOKIE;
2108 
2109 	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2110 	if (err)
2111 		goto out;
2112 
2113 	offset = vfs_llseek(file, offset, SEEK_SET);
2114 	if (offset < 0) {
2115 		err = nfserrno((int)offset);
2116 		goto out_close;
2117 	}
2118 
2119 	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2120 
2121 	if (err == nfserr_eof || err == nfserr_toosmall)
2122 		err = nfs_ok; /* can still be found in ->err */
2123 out_close:
2124 	fput(file);
2125 out:
2126 	return err;
2127 }
2128 
2129 /*
2130  * Get file system stats
2131  * N.B. After this call fhp needs an fh_put
2132  */
2133 __be32
nfsd_statfs(struct svc_rqst * rqstp,struct svc_fh * fhp,struct kstatfs * stat,int access)2134 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2135 {
2136 	__be32 err;
2137 
2138 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2139 	if (!err) {
2140 		struct path path = {
2141 			.mnt	= fhp->fh_export->ex_path.mnt,
2142 			.dentry	= fhp->fh_dentry,
2143 		};
2144 		if (vfs_statfs(&path, stat))
2145 			err = nfserr_io;
2146 	}
2147 	return err;
2148 }
2149 
exp_rdonly(struct svc_rqst * rqstp,struct svc_export * exp)2150 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2151 {
2152 	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2153 }
2154 
2155 #ifdef CONFIG_NFSD_V4
2156 /*
2157  * Helper function to translate error numbers. In the case of xattr operations,
2158  * some error codes need to be translated outside of the standard translations.
2159  *
2160  * ENODATA needs to be translated to nfserr_noxattr.
2161  * E2BIG to nfserr_xattr2big.
2162  *
2163  * Additionally, vfs_listxattr can return -ERANGE. This means that the
2164  * file has too many extended attributes to retrieve inside an
2165  * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2166  * filesystems will allow the adding of extended attributes until they hit
2167  * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2168  * So, at that point, the attributes are present and valid, but can't
2169  * be retrieved using listxattr, since the upper level xattr code enforces
2170  * the XATTR_LIST_MAX limit.
2171  *
2172  * This bug means that we need to deal with listxattr returning -ERANGE. The
2173  * best mapping is to return TOOSMALL.
2174  */
2175 static __be32
nfsd_xattr_errno(int err)2176 nfsd_xattr_errno(int err)
2177 {
2178 	switch (err) {
2179 	case -ENODATA:
2180 		return nfserr_noxattr;
2181 	case -E2BIG:
2182 		return nfserr_xattr2big;
2183 	case -ERANGE:
2184 		return nfserr_toosmall;
2185 	}
2186 	return nfserrno(err);
2187 }
2188 
2189 /*
2190  * Retrieve the specified user extended attribute. To avoid always
2191  * having to allocate the maximum size (since we are not getting
2192  * a maximum size from the RPC), do a probe + alloc. Hold a reader
2193  * lock on i_rwsem to prevent the extended attribute from changing
2194  * size while we're doing this.
2195  */
2196 __be32
nfsd_getxattr(struct svc_rqst * rqstp,struct svc_fh * fhp,char * name,void ** bufp,int * lenp)2197 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2198 	      void **bufp, int *lenp)
2199 {
2200 	ssize_t len;
2201 	__be32 err;
2202 	char *buf;
2203 	struct inode *inode;
2204 	struct dentry *dentry;
2205 
2206 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2207 	if (err)
2208 		return err;
2209 
2210 	err = nfs_ok;
2211 	dentry = fhp->fh_dentry;
2212 	inode = d_inode(dentry);
2213 
2214 	inode_lock_shared(inode);
2215 
2216 	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, NULL, 0);
2217 
2218 	/*
2219 	 * Zero-length attribute, just return.
2220 	 */
2221 	if (len == 0) {
2222 		*bufp = NULL;
2223 		*lenp = 0;
2224 		goto out;
2225 	}
2226 
2227 	if (len < 0) {
2228 		err = nfsd_xattr_errno(len);
2229 		goto out;
2230 	}
2231 
2232 	if (len > *lenp) {
2233 		err = nfserr_toosmall;
2234 		goto out;
2235 	}
2236 
2237 	buf = kvmalloc(len, GFP_KERNEL);
2238 	if (buf == NULL) {
2239 		err = nfserr_jukebox;
2240 		goto out;
2241 	}
2242 
2243 	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, buf, len);
2244 	if (len <= 0) {
2245 		kvfree(buf);
2246 		buf = NULL;
2247 		err = nfsd_xattr_errno(len);
2248 	}
2249 
2250 	*lenp = len;
2251 	*bufp = buf;
2252 
2253 out:
2254 	inode_unlock_shared(inode);
2255 
2256 	return err;
2257 }
2258 
2259 /*
2260  * Retrieve the xattr names. Since we can't know how many are
2261  * user extended attributes, we must get all attributes here,
2262  * and have the XDR encode filter out the "user." ones.
2263  *
2264  * While this could always just allocate an XATTR_LIST_MAX
2265  * buffer, that's a waste, so do a probe + allocate. To
2266  * avoid any changes between the probe and allocate, wrap
2267  * this in inode_lock.
2268  */
2269 __be32
nfsd_listxattr(struct svc_rqst * rqstp,struct svc_fh * fhp,char ** bufp,int * lenp)2270 nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2271 	       int *lenp)
2272 {
2273 	ssize_t len;
2274 	__be32 err;
2275 	char *buf;
2276 	struct inode *inode;
2277 	struct dentry *dentry;
2278 
2279 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2280 	if (err)
2281 		return err;
2282 
2283 	dentry = fhp->fh_dentry;
2284 	inode = d_inode(dentry);
2285 	*lenp = 0;
2286 
2287 	inode_lock_shared(inode);
2288 
2289 	len = vfs_listxattr(dentry, NULL, 0);
2290 	if (len <= 0) {
2291 		err = nfsd_xattr_errno(len);
2292 		goto out;
2293 	}
2294 
2295 	if (len > XATTR_LIST_MAX) {
2296 		err = nfserr_xattr2big;
2297 		goto out;
2298 	}
2299 
2300 	buf = kvmalloc(len, GFP_KERNEL);
2301 	if (buf == NULL) {
2302 		err = nfserr_jukebox;
2303 		goto out;
2304 	}
2305 
2306 	len = vfs_listxattr(dentry, buf, len);
2307 	if (len <= 0) {
2308 		kvfree(buf);
2309 		err = nfsd_xattr_errno(len);
2310 		goto out;
2311 	}
2312 
2313 	*lenp = len;
2314 	*bufp = buf;
2315 
2316 	err = nfs_ok;
2317 out:
2318 	inode_unlock_shared(inode);
2319 
2320 	return err;
2321 }
2322 
2323 /**
2324  * nfsd_removexattr - Remove an extended attribute
2325  * @rqstp: RPC transaction being executed
2326  * @fhp: NFS filehandle of object with xattr to remove
2327  * @name: name of xattr to remove (NUL-terminate)
2328  *
2329  * Pass in a NULL pointer for delegated_inode, and let the client deal
2330  * with NFS4ERR_DELAY (same as with e.g. setattr and remove).
2331  *
2332  * Returns nfs_ok on success, or an nfsstat in network byte order.
2333  */
2334 __be32
nfsd_removexattr(struct svc_rqst * rqstp,struct svc_fh * fhp,char * name)2335 nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2336 {
2337 	__be32 err;
2338 	int ret;
2339 
2340 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2341 	if (err)
2342 		return err;
2343 
2344 	ret = fh_want_write(fhp);
2345 	if (ret)
2346 		return nfserrno(ret);
2347 
2348 	inode_lock(fhp->fh_dentry->d_inode);
2349 	err = fh_fill_pre_attrs(fhp);
2350 	if (err != nfs_ok)
2351 		goto out_unlock;
2352 	ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2353 				       name, NULL);
2354 	err = nfsd_xattr_errno(ret);
2355 	fh_fill_post_attrs(fhp);
2356 out_unlock:
2357 	inode_unlock(fhp->fh_dentry->d_inode);
2358 	fh_drop_write(fhp);
2359 
2360 	return err;
2361 }
2362 
2363 __be32
nfsd_setxattr(struct svc_rqst * rqstp,struct svc_fh * fhp,char * name,void * buf,u32 len,u32 flags)2364 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2365 	      void *buf, u32 len, u32 flags)
2366 {
2367 	__be32 err;
2368 	int ret;
2369 
2370 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2371 	if (err)
2372 		return err;
2373 
2374 	ret = fh_want_write(fhp);
2375 	if (ret)
2376 		return nfserrno(ret);
2377 	inode_lock(fhp->fh_dentry->d_inode);
2378 	err = fh_fill_pre_attrs(fhp);
2379 	if (err != nfs_ok)
2380 		goto out_unlock;
2381 	ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2382 				    name, buf, len, flags, NULL);
2383 	fh_fill_post_attrs(fhp);
2384 	err = nfsd_xattr_errno(ret);
2385 out_unlock:
2386 	inode_unlock(fhp->fh_dentry->d_inode);
2387 	fh_drop_write(fhp);
2388 	return err;
2389 }
2390 #endif
2391 
2392 /*
2393  * Check for a user's access permissions to this inode.
2394  */
2395 __be32
nfsd_permission(struct svc_rqst * rqstp,struct svc_export * exp,struct dentry * dentry,int acc)2396 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2397 					struct dentry *dentry, int acc)
2398 {
2399 	struct inode	*inode = d_inode(dentry);
2400 	int		err;
2401 
2402 	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2403 		return 0;
2404 #if 0
2405 	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2406 		acc,
2407 		(acc & NFSD_MAY_READ)?	" read"  : "",
2408 		(acc & NFSD_MAY_WRITE)?	" write" : "",
2409 		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2410 		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2411 		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2412 		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2413 		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2414 		inode->i_mode,
2415 		IS_IMMUTABLE(inode)?	" immut" : "",
2416 		IS_APPEND(inode)?	" append" : "",
2417 		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2418 	dprintk("      owner %d/%d user %d/%d\n",
2419 		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2420 #endif
2421 
2422 	/* Normally we reject any write/sattr etc access on a read-only file
2423 	 * system.  But if it is IRIX doing check on write-access for a
2424 	 * device special file, we ignore rofs.
2425 	 */
2426 	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2427 		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2428 			if (exp_rdonly(rqstp, exp) ||
2429 			    __mnt_is_readonly(exp->ex_path.mnt))
2430 				return nfserr_rofs;
2431 			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2432 				return nfserr_perm;
2433 		}
2434 	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2435 		return nfserr_perm;
2436 
2437 	if (acc & NFSD_MAY_LOCK) {
2438 		/* If we cannot rely on authentication in NLM requests,
2439 		 * just allow locks, otherwise require read permission, or
2440 		 * ownership
2441 		 */
2442 		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2443 			return 0;
2444 		else
2445 			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2446 	}
2447 	/*
2448 	 * The file owner always gets access permission for accesses that
2449 	 * would normally be checked at open time. This is to make
2450 	 * file access work even when the client has done a fchmod(fd, 0).
2451 	 *
2452 	 * However, `cp foo bar' should fail nevertheless when bar is
2453 	 * readonly. A sensible way to do this might be to reject all
2454 	 * attempts to truncate a read-only file, because a creat() call
2455 	 * always implies file truncation.
2456 	 * ... but this isn't really fair.  A process may reasonably call
2457 	 * ftruncate on an open file descriptor on a file with perm 000.
2458 	 * We must trust the client to do permission checking - using "ACCESS"
2459 	 * with NFSv3.
2460 	 */
2461 	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2462 	    uid_eq(inode->i_uid, current_fsuid()))
2463 		return 0;
2464 
2465 	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2466 	err = inode_permission(&nop_mnt_idmap, inode,
2467 			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2468 
2469 	/* Allow read access to binaries even when mode 111 */
2470 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2471 	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2472 	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2473 		err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
2474 
2475 	return err? nfserrno(err) : 0;
2476 }
2477