xref: /openbmc/linux/fs/nfsd/vfs.c (revision 2010776f)
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/slab.h>
30 #include <linux/uaccess.h>
31 #include <linux/exportfs.h>
32 #include <linux/writeback.h>
33 #include <linux/security.h>
34 
35 #ifdef CONFIG_NFSD_V3
36 #include "xdr3.h"
37 #endif /* CONFIG_NFSD_V3 */
38 
39 #ifdef CONFIG_NFSD_V4
40 #include "../internal.h"
41 #include "acl.h"
42 #include "idmap.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  * Called from nfsd_lookup and encode_dirent. Check if we have crossed
54  * a mount point.
55  * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
56  *  or nfs_ok having possibly changed *dpp and *expp
57  */
58 int
59 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
60 		        struct svc_export **expp)
61 {
62 	struct svc_export *exp = *expp, *exp2 = NULL;
63 	struct dentry *dentry = *dpp;
64 	struct path path = {.mnt = mntget(exp->ex_path.mnt),
65 			    .dentry = dget(dentry)};
66 	int err = 0;
67 
68 	err = follow_down(&path);
69 	if (err < 0)
70 		goto out;
71 	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
72 	    nfsd_mountpoint(dentry, exp) == 2) {
73 		/* This is only a mountpoint in some other namespace */
74 		path_put(&path);
75 		goto out;
76 	}
77 
78 	exp2 = rqst_exp_get_by_name(rqstp, &path);
79 	if (IS_ERR(exp2)) {
80 		err = PTR_ERR(exp2);
81 		/*
82 		 * We normally allow NFS clients to continue
83 		 * "underneath" a mountpoint that is not exported.
84 		 * The exception is V4ROOT, where no traversal is ever
85 		 * allowed without an explicit export of the new
86 		 * directory.
87 		 */
88 		if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
89 			err = 0;
90 		path_put(&path);
91 		goto out;
92 	}
93 	if (nfsd_v4client(rqstp) ||
94 		(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
95 		/* successfully crossed mount point */
96 		/*
97 		 * This is subtle: path.dentry is *not* on path.mnt
98 		 * at this point.  The only reason we are safe is that
99 		 * original mnt is pinned down by exp, so we should
100 		 * put path *before* putting exp
101 		 */
102 		*dpp = path.dentry;
103 		path.dentry = dentry;
104 		*expp = exp2;
105 		exp2 = exp;
106 	}
107 	path_put(&path);
108 	exp_put(exp2);
109 out:
110 	return err;
111 }
112 
113 static void follow_to_parent(struct path *path)
114 {
115 	struct dentry *dp;
116 
117 	while (path->dentry == path->mnt->mnt_root && follow_up(path))
118 		;
119 	dp = dget_parent(path->dentry);
120 	dput(path->dentry);
121 	path->dentry = dp;
122 }
123 
124 static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
125 {
126 	struct svc_export *exp2;
127 	struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
128 			    .dentry = dget(dparent)};
129 
130 	follow_to_parent(&path);
131 
132 	exp2 = rqst_exp_parent(rqstp, &path);
133 	if (PTR_ERR(exp2) == -ENOENT) {
134 		*dentryp = dget(dparent);
135 	} else if (IS_ERR(exp2)) {
136 		path_put(&path);
137 		return PTR_ERR(exp2);
138 	} else {
139 		*dentryp = dget(path.dentry);
140 		exp_put(*exp);
141 		*exp = exp2;
142 	}
143 	path_put(&path);
144 	return 0;
145 }
146 
147 /*
148  * For nfsd purposes, we treat V4ROOT exports as though there was an
149  * export at *every* directory.
150  * We return:
151  * '1' if this dentry *must* be an export point,
152  * '2' if it might be, if there is really a mount here, and
153  * '0' if there is no chance of an export point here.
154  */
155 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
156 {
157 	if (!d_inode(dentry))
158 		return 0;
159 	if (exp->ex_flags & NFSEXP_V4ROOT)
160 		return 1;
161 	if (nfsd4_is_junction(dentry))
162 		return 1;
163 	if (d_mountpoint(dentry))
164 		/*
165 		 * Might only be a mountpoint in a different namespace,
166 		 * but we need to check.
167 		 */
168 		return 2;
169 	return 0;
170 }
171 
172 __be32
173 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
174 		   const char *name, unsigned int len,
175 		   struct svc_export **exp_ret, struct dentry **dentry_ret)
176 {
177 	struct svc_export	*exp;
178 	struct dentry		*dparent;
179 	struct dentry		*dentry;
180 	int			host_err;
181 
182 	dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
183 
184 	dparent = fhp->fh_dentry;
185 	exp = exp_get(fhp->fh_export);
186 
187 	/* Lookup the name, but don't follow links */
188 	if (isdotent(name, len)) {
189 		if (len==1)
190 			dentry = dget(dparent);
191 		else if (dparent != exp->ex_path.dentry)
192 			dentry = dget_parent(dparent);
193 		else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
194 			dentry = dget(dparent); /* .. == . just like at / */
195 		else {
196 			/* checking mountpoint crossing is very different when stepping up */
197 			host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
198 			if (host_err)
199 				goto out_nfserr;
200 		}
201 	} else {
202 		/*
203 		 * In the nfsd4_open() case, this may be held across
204 		 * subsequent open and delegation acquisition which may
205 		 * need to take the child's i_mutex:
206 		 */
207 		fh_lock_nested(fhp, I_MUTEX_PARENT);
208 		dentry = lookup_one_len(name, dparent, len);
209 		host_err = PTR_ERR(dentry);
210 		if (IS_ERR(dentry))
211 			goto out_nfserr;
212 		if (nfsd_mountpoint(dentry, exp)) {
213 			/*
214 			 * We don't need the i_mutex after all.  It's
215 			 * still possible we could open this (regular
216 			 * files can be mountpoints too), but the
217 			 * i_mutex is just there to prevent renames of
218 			 * something that we might be about to delegate,
219 			 * and a mountpoint won't be renamed:
220 			 */
221 			fh_unlock(fhp);
222 			if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
223 				dput(dentry);
224 				goto out_nfserr;
225 			}
226 		}
227 	}
228 	*dentry_ret = dentry;
229 	*exp_ret = exp;
230 	return 0;
231 
232 out_nfserr:
233 	exp_put(exp);
234 	return nfserrno(host_err);
235 }
236 
237 /*
238  * Look up one component of a pathname.
239  * N.B. After this call _both_ fhp and resfh need an fh_put
240  *
241  * If the lookup would cross a mountpoint, and the mounted filesystem
242  * is exported to the client with NFSEXP_NOHIDE, then the lookup is
243  * accepted as it stands and the mounted directory is
244  * returned. Otherwise the covered directory is returned.
245  * NOTE: this mountpoint crossing is not supported properly by all
246  *   clients and is explicitly disallowed for NFSv3
247  */
248 __be32
249 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
250 				unsigned int len, struct svc_fh *resfh)
251 {
252 	struct svc_export	*exp;
253 	struct dentry		*dentry;
254 	__be32 err;
255 
256 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
257 	if (err)
258 		return err;
259 	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
260 	if (err)
261 		return err;
262 	err = check_nfsd_access(exp, rqstp);
263 	if (err)
264 		goto out;
265 	/*
266 	 * Note: we compose the file handle now, but as the
267 	 * dentry may be negative, it may need to be updated.
268 	 */
269 	err = fh_compose(resfh, exp, dentry, fhp);
270 	if (!err && d_really_is_negative(dentry))
271 		err = nfserr_noent;
272 out:
273 	dput(dentry);
274 	exp_put(exp);
275 	return err;
276 }
277 
278 /*
279  * Commit metadata changes to stable storage.
280  */
281 static int
282 commit_inode_metadata(struct inode *inode)
283 {
284 	const struct export_operations *export_ops = inode->i_sb->s_export_op;
285 
286 	if (export_ops->commit_metadata)
287 		return export_ops->commit_metadata(inode);
288 	return sync_inode_metadata(inode, 1);
289 }
290 
291 static int
292 commit_metadata(struct svc_fh *fhp)
293 {
294 	struct inode *inode = d_inode(fhp->fh_dentry);
295 
296 	if (!EX_ISSYNC(fhp->fh_export))
297 		return 0;
298 	return commit_inode_metadata(inode);
299 }
300 
301 /*
302  * Go over the attributes and take care of the small differences between
303  * NFS semantics and what Linux expects.
304  */
305 static void
306 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
307 {
308 	/* sanitize the mode change */
309 	if (iap->ia_valid & ATTR_MODE) {
310 		iap->ia_mode &= S_IALLUGO;
311 		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
312 	}
313 
314 	/* Revoke setuid/setgid on chown */
315 	if (!S_ISDIR(inode->i_mode) &&
316 	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
317 		iap->ia_valid |= ATTR_KILL_PRIV;
318 		if (iap->ia_valid & ATTR_MODE) {
319 			/* we're setting mode too, just clear the s*id bits */
320 			iap->ia_mode &= ~S_ISUID;
321 			if (iap->ia_mode & S_IXGRP)
322 				iap->ia_mode &= ~S_ISGID;
323 		} else {
324 			/* set ATTR_KILL_* bits and let VFS handle it */
325 			iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
326 		}
327 	}
328 }
329 
330 static __be32
331 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
332 		struct iattr *iap)
333 {
334 	struct inode *inode = d_inode(fhp->fh_dentry);
335 
336 	if (iap->ia_size < inode->i_size) {
337 		__be32 err;
338 
339 		err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
340 				NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
341 		if (err)
342 			return err;
343 	}
344 	return nfserrno(get_write_access(inode));
345 }
346 
347 /*
348  * Set various file attributes.  After this call fhp needs an fh_put.
349  */
350 __be32
351 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
352 	     int check_guard, time64_t guardtime)
353 {
354 	struct dentry	*dentry;
355 	struct inode	*inode;
356 	int		accmode = NFSD_MAY_SATTR;
357 	umode_t		ftype = 0;
358 	__be32		err;
359 	int		host_err;
360 	bool		get_write_count;
361 	bool		size_change = (iap->ia_valid & ATTR_SIZE);
362 
363 	if (iap->ia_valid & ATTR_SIZE) {
364 		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
365 		ftype = S_IFREG;
366 	}
367 
368 	/*
369 	 * If utimes(2) and friends are called with times not NULL, we should
370 	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
371 	 * will return EACCES, when the caller's effective UID does not match
372 	 * the owner of the file, and the caller is not privileged. In this
373 	 * situation, we should return EPERM(notify_change will return this).
374 	 */
375 	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
376 		accmode |= NFSD_MAY_OWNER_OVERRIDE;
377 		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
378 			accmode |= NFSD_MAY_WRITE;
379 	}
380 
381 	/* Callers that do fh_verify should do the fh_want_write: */
382 	get_write_count = !fhp->fh_dentry;
383 
384 	/* Get inode */
385 	err = fh_verify(rqstp, fhp, ftype, accmode);
386 	if (err)
387 		return err;
388 	if (get_write_count) {
389 		host_err = fh_want_write(fhp);
390 		if (host_err)
391 			goto out;
392 	}
393 
394 	dentry = fhp->fh_dentry;
395 	inode = d_inode(dentry);
396 
397 	/* Ignore any mode updates on symlinks */
398 	if (S_ISLNK(inode->i_mode))
399 		iap->ia_valid &= ~ATTR_MODE;
400 
401 	if (!iap->ia_valid)
402 		return 0;
403 
404 	nfsd_sanitize_attrs(inode, iap);
405 
406 	if (check_guard && guardtime != inode->i_ctime.tv_sec)
407 		return nfserr_notsync;
408 
409 	/*
410 	 * The size case is special, it changes the file in addition to the
411 	 * attributes, and file systems don't expect it to be mixed with
412 	 * "random" attribute changes.  We thus split out the size change
413 	 * into a separate call to ->setattr, and do the rest as a separate
414 	 * setattr call.
415 	 */
416 	if (size_change) {
417 		err = nfsd_get_write_access(rqstp, fhp, iap);
418 		if (err)
419 			return err;
420 	}
421 
422 	fh_lock(fhp);
423 	if (size_change) {
424 		/*
425 		 * RFC5661, Section 18.30.4:
426 		 *   Changing the size of a file with SETATTR indirectly
427 		 *   changes the time_modify and change attributes.
428 		 *
429 		 * (and similar for the older RFCs)
430 		 */
431 		struct iattr size_attr = {
432 			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
433 			.ia_size	= iap->ia_size,
434 		};
435 
436 		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
437 		if (host_err)
438 			goto out_unlock;
439 		iap->ia_valid &= ~ATTR_SIZE;
440 
441 		/*
442 		 * Avoid the additional setattr call below if the only other
443 		 * attribute that the client sends is the mtime, as we update
444 		 * it as part of the size change above.
445 		 */
446 		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
447 			goto out_unlock;
448 	}
449 
450 	iap->ia_valid |= ATTR_CTIME;
451 	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
452 
453 out_unlock:
454 	fh_unlock(fhp);
455 	if (size_change)
456 		put_write_access(inode);
457 out:
458 	if (!host_err)
459 		host_err = commit_metadata(fhp);
460 	return nfserrno(host_err);
461 }
462 
463 #if defined(CONFIG_NFSD_V4)
464 /*
465  * NFS junction information is stored in an extended attribute.
466  */
467 #define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
468 
469 /**
470  * nfsd4_is_junction - Test if an object could be an NFS junction
471  *
472  * @dentry: object to test
473  *
474  * Returns 1 if "dentry" appears to contain NFS junction information.
475  * Otherwise 0 is returned.
476  */
477 int nfsd4_is_junction(struct dentry *dentry)
478 {
479 	struct inode *inode = d_inode(dentry);
480 
481 	if (inode == NULL)
482 		return 0;
483 	if (inode->i_mode & S_IXUGO)
484 		return 0;
485 	if (!(inode->i_mode & S_ISVTX))
486 		return 0;
487 	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
488 			 NULL, 0) <= 0)
489 		return 0;
490 	return 1;
491 }
492 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
493 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
494 		struct xdr_netobj *label)
495 {
496 	__be32 error;
497 	int host_error;
498 	struct dentry *dentry;
499 
500 	error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
501 	if (error)
502 		return error;
503 
504 	dentry = fhp->fh_dentry;
505 
506 	inode_lock(d_inode(dentry));
507 	host_error = security_inode_setsecctx(dentry, label->data, label->len);
508 	inode_unlock(d_inode(dentry));
509 	return nfserrno(host_error);
510 }
511 #else
512 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
513 		struct xdr_netobj *label)
514 {
515 	return nfserr_notsupp;
516 }
517 #endif
518 
519 __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos,
520 		struct nfsd_file *nf_dst, u64 dst_pos, u64 count, bool sync)
521 {
522 	struct file *src = nf_src->nf_file;
523 	struct file *dst = nf_dst->nf_file;
524 	loff_t cloned;
525 	__be32 ret = 0;
526 
527 	down_write(&nf_dst->nf_rwsem);
528 	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
529 	if (cloned < 0) {
530 		ret = nfserrno(cloned);
531 		goto out_err;
532 	}
533 	if (count && cloned != count) {
534 		ret = nfserrno(-EINVAL);
535 		goto out_err;
536 	}
537 	if (sync) {
538 		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
539 		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
540 
541 		if (!status)
542 			status = commit_inode_metadata(file_inode(src));
543 		if (status < 0) {
544 			nfsd_reset_boot_verifier(net_generic(nf_dst->nf_net,
545 						 nfsd_net_id));
546 			ret = nfserrno(status);
547 		}
548 	}
549 out_err:
550 	up_write(&nf_dst->nf_rwsem);
551 	return ret;
552 }
553 
554 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
555 			     u64 dst_pos, u64 count)
556 {
557 
558 	/*
559 	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
560 	 * thread and client rpc slot.  The choice of 4MB is somewhat
561 	 * arbitrary.  We might instead base this on r/wsize, or make it
562 	 * tunable, or use a time instead of a byte limit, or implement
563 	 * asynchronous copy.  In theory a client could also recognize a
564 	 * limit like this and pipeline multiple COPY requests.
565 	 */
566 	count = min_t(u64, count, 1 << 22);
567 	return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
568 }
569 
570 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
571 			   struct file *file, loff_t offset, loff_t len,
572 			   int flags)
573 {
574 	int error;
575 
576 	if (!S_ISREG(file_inode(file)->i_mode))
577 		return nfserr_inval;
578 
579 	error = vfs_fallocate(file, flags, offset, len);
580 	if (!error)
581 		error = commit_metadata(fhp);
582 
583 	return nfserrno(error);
584 }
585 #endif /* defined(CONFIG_NFSD_V4) */
586 
587 #ifdef CONFIG_NFSD_V3
588 /*
589  * Check server access rights to a file system object
590  */
591 struct accessmap {
592 	u32		access;
593 	int		how;
594 };
595 static struct accessmap	nfs3_regaccess[] = {
596     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
597     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
598     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
599     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
600 
601 #ifdef CONFIG_NFSD_V4
602     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
603     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
604     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
605 #endif
606 
607     {	0,			0				}
608 };
609 
610 static struct accessmap	nfs3_diraccess[] = {
611     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
612     {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
613     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
614     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
615     {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
616 
617 #ifdef CONFIG_NFSD_V4
618     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
619     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
620     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
621 #endif
622 
623     {	0,			0				}
624 };
625 
626 static struct accessmap	nfs3_anyaccess[] = {
627 	/* Some clients - Solaris 2.6 at least, make an access call
628 	 * to the server to check for access for things like /dev/null
629 	 * (which really, the server doesn't care about).  So
630 	 * We provide simple access checking for them, looking
631 	 * mainly at mode bits, and we make sure to ignore read-only
632 	 * filesystem checks
633 	 */
634     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
635     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
636     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
637     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
638 
639     {	0,			0				}
640 };
641 
642 __be32
643 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
644 {
645 	struct accessmap	*map;
646 	struct svc_export	*export;
647 	struct dentry		*dentry;
648 	u32			query, result = 0, sresult = 0;
649 	__be32			error;
650 
651 	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
652 	if (error)
653 		goto out;
654 
655 	export = fhp->fh_export;
656 	dentry = fhp->fh_dentry;
657 
658 	if (d_is_reg(dentry))
659 		map = nfs3_regaccess;
660 	else if (d_is_dir(dentry))
661 		map = nfs3_diraccess;
662 	else
663 		map = nfs3_anyaccess;
664 
665 
666 	query = *access;
667 	for  (; map->access; map++) {
668 		if (map->access & query) {
669 			__be32 err2;
670 
671 			sresult |= map->access;
672 
673 			err2 = nfsd_permission(rqstp, export, dentry, map->how);
674 			switch (err2) {
675 			case nfs_ok:
676 				result |= map->access;
677 				break;
678 
679 			/* the following error codes just mean the access was not allowed,
680 			 * rather than an error occurred */
681 			case nfserr_rofs:
682 			case nfserr_acces:
683 			case nfserr_perm:
684 				/* simply don't "or" in the access bit. */
685 				break;
686 			default:
687 				error = err2;
688 				goto out;
689 			}
690 		}
691 	}
692 	*access = result;
693 	if (supported)
694 		*supported = sresult;
695 
696  out:
697 	return error;
698 }
699 #endif /* CONFIG_NFSD_V3 */
700 
701 int nfsd_open_break_lease(struct inode *inode, int access)
702 {
703 	unsigned int mode;
704 
705 	if (access & NFSD_MAY_NOT_BREAK_LEASE)
706 		return 0;
707 	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
708 	return break_lease(inode, mode | O_NONBLOCK);
709 }
710 
711 /*
712  * Open an existing file or directory.
713  * The may_flags argument indicates the type of open (read/write/lock)
714  * and additional flags.
715  * N.B. After this call fhp needs an fh_put
716  */
717 static __be32
718 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
719 			int may_flags, struct file **filp)
720 {
721 	struct path	path;
722 	struct inode	*inode;
723 	struct file	*file;
724 	int		flags = O_RDONLY|O_LARGEFILE;
725 	__be32		err;
726 	int		host_err = 0;
727 
728 	path.mnt = fhp->fh_export->ex_path.mnt;
729 	path.dentry = fhp->fh_dentry;
730 	inode = d_inode(path.dentry);
731 
732 	/* Disallow write access to files with the append-only bit set
733 	 * or any access when mandatory locking enabled
734 	 */
735 	err = nfserr_perm;
736 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
737 		goto out;
738 
739 	if (!inode->i_fop)
740 		goto out;
741 
742 	host_err = nfsd_open_break_lease(inode, may_flags);
743 	if (host_err) /* NOMEM or WOULDBLOCK */
744 		goto out_nfserr;
745 
746 	if (may_flags & NFSD_MAY_WRITE) {
747 		if (may_flags & NFSD_MAY_READ)
748 			flags = O_RDWR|O_LARGEFILE;
749 		else
750 			flags = O_WRONLY|O_LARGEFILE;
751 	}
752 
753 	file = dentry_open(&path, flags, current_cred());
754 	if (IS_ERR(file)) {
755 		host_err = PTR_ERR(file);
756 		goto out_nfserr;
757 	}
758 
759 	host_err = ima_file_check(file, may_flags);
760 	if (host_err) {
761 		fput(file);
762 		goto out_nfserr;
763 	}
764 
765 	if (may_flags & NFSD_MAY_64BIT_COOKIE)
766 		file->f_mode |= FMODE_64BITHASH;
767 	else
768 		file->f_mode |= FMODE_32BITHASH;
769 
770 	*filp = file;
771 out_nfserr:
772 	err = nfserrno(host_err);
773 out:
774 	return err;
775 }
776 
777 __be32
778 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
779 		int may_flags, struct file **filp)
780 {
781 	__be32 err;
782 
783 	validate_process_creds();
784 	/*
785 	 * If we get here, then the client has already done an "open",
786 	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
787 	 * in case a chmod has now revoked permission.
788 	 *
789 	 * Arguably we should also allow the owner override for
790 	 * directories, but we never have and it doesn't seem to have
791 	 * caused anyone a problem.  If we were to change this, note
792 	 * also that our filldir callbacks would need a variant of
793 	 * lookup_one_len that doesn't check permissions.
794 	 */
795 	if (type == S_IFREG)
796 		may_flags |= NFSD_MAY_OWNER_OVERRIDE;
797 	err = fh_verify(rqstp, fhp, type, may_flags);
798 	if (!err)
799 		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
800 	validate_process_creds();
801 	return err;
802 }
803 
804 __be32
805 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
806 		int may_flags, struct file **filp)
807 {
808 	__be32 err;
809 
810 	validate_process_creds();
811 	err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
812 	validate_process_creds();
813 	return err;
814 }
815 
816 /*
817  * Grab and keep cached pages associated with a file in the svc_rqst
818  * so that they can be passed to the network sendmsg/sendpage routines
819  * directly. They will be released after the sending has completed.
820  */
821 static int
822 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
823 		  struct splice_desc *sd)
824 {
825 	struct svc_rqst *rqstp = sd->u.data;
826 	struct page **pp = rqstp->rq_next_page;
827 	struct page *page = buf->page;
828 
829 	if (rqstp->rq_res.page_len == 0) {
830 		svc_rqst_replace_page(rqstp, page);
831 		rqstp->rq_res.page_base = buf->offset;
832 	} else if (page != pp[-1]) {
833 		svc_rqst_replace_page(rqstp, page);
834 	}
835 	rqstp->rq_res.page_len += sd->len;
836 
837 	return sd->len;
838 }
839 
840 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
841 				    struct splice_desc *sd)
842 {
843 	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
844 }
845 
846 static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
847 		size_t expected)
848 {
849 	if (expected != 0 && len == 0)
850 		return 1;
851 	if (offset+len >= i_size_read(file_inode(file)))
852 		return 1;
853 	return 0;
854 }
855 
856 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
857 			       struct file *file, loff_t offset,
858 			       unsigned long *count, u32 *eof, ssize_t host_err)
859 {
860 	if (host_err >= 0) {
861 		nfsd_stats_io_read_add(fhp->fh_export, host_err);
862 		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
863 		*count = host_err;
864 		fsnotify_access(file);
865 		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
866 		return 0;
867 	} else {
868 		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
869 		return nfserrno(host_err);
870 	}
871 }
872 
873 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
874 			struct file *file, loff_t offset, unsigned long *count,
875 			u32 *eof)
876 {
877 	struct splice_desc sd = {
878 		.len		= 0,
879 		.total_len	= *count,
880 		.pos		= offset,
881 		.u.data		= rqstp,
882 	};
883 	ssize_t host_err;
884 
885 	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
886 	rqstp->rq_next_page = rqstp->rq_respages + 1;
887 	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
888 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
889 }
890 
891 __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
892 		  struct file *file, loff_t offset,
893 		  struct kvec *vec, int vlen, unsigned long *count,
894 		  u32 *eof)
895 {
896 	struct iov_iter iter;
897 	loff_t ppos = offset;
898 	ssize_t host_err;
899 
900 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
901 	iov_iter_kvec(&iter, READ, vec, vlen, *count);
902 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
903 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
904 }
905 
906 /*
907  * Gathered writes: If another process is currently writing to the file,
908  * there's a high chance this is another nfsd (triggered by a bulk write
909  * from a client's biod). Rather than syncing the file with each write
910  * request, we sleep for 10 msec.
911  *
912  * I don't know if this roughly approximates C. Juszak's idea of
913  * gathered writes, but it's a nice and simple solution (IMHO), and it
914  * seems to work:-)
915  *
916  * Note: we do this only in the NFSv2 case, since v3 and higher have a
917  * better tool (separate unstable writes and commits) for solving this
918  * problem.
919  */
920 static int wait_for_concurrent_writes(struct file *file)
921 {
922 	struct inode *inode = file_inode(file);
923 	static ino_t last_ino;
924 	static dev_t last_dev;
925 	int err = 0;
926 
927 	if (atomic_read(&inode->i_writecount) > 1
928 	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
929 		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
930 		msleep(10);
931 		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
932 	}
933 
934 	if (inode->i_state & I_DIRTY) {
935 		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
936 		err = vfs_fsync(file, 0);
937 	}
938 	last_ino = inode->i_ino;
939 	last_dev = inode->i_sb->s_dev;
940 	return err;
941 }
942 
943 __be32
944 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
945 				loff_t offset, struct kvec *vec, int vlen,
946 				unsigned long *cnt, int stable,
947 				__be32 *verf)
948 {
949 	struct file		*file = nf->nf_file;
950 	struct super_block	*sb = file_inode(file)->i_sb;
951 	struct svc_export	*exp;
952 	struct iov_iter		iter;
953 	__be32			nfserr;
954 	int			host_err;
955 	int			use_wgather;
956 	loff_t			pos = offset;
957 	unsigned long		exp_op_flags = 0;
958 	unsigned int		pflags = current->flags;
959 	rwf_t			flags = 0;
960 	bool			restore_flags = false;
961 
962 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
963 
964 	if (sb->s_export_op)
965 		exp_op_flags = sb->s_export_op->flags;
966 
967 	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
968 	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
969 		/*
970 		 * We want throttling in balance_dirty_pages()
971 		 * and shrink_inactive_list() to only consider
972 		 * the backingdev we are writing to, so that nfs to
973 		 * localhost doesn't cause nfsd to lock up due to all
974 		 * the client's dirty pages or its congested queue.
975 		 */
976 		current->flags |= PF_LOCAL_THROTTLE;
977 		restore_flags = true;
978 	}
979 
980 	exp = fhp->fh_export;
981 	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
982 
983 	if (!EX_ISSYNC(exp))
984 		stable = NFS_UNSTABLE;
985 
986 	if (stable && !use_wgather)
987 		flags |= RWF_SYNC;
988 
989 	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
990 	if (flags & RWF_SYNC) {
991 		down_write(&nf->nf_rwsem);
992 		host_err = vfs_iter_write(file, &iter, &pos, flags);
993 		if (host_err < 0)
994 			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
995 						 nfsd_net_id));
996 		up_write(&nf->nf_rwsem);
997 	} else {
998 		down_read(&nf->nf_rwsem);
999 		if (verf)
1000 			nfsd_copy_boot_verifier(verf,
1001 					net_generic(SVC_NET(rqstp),
1002 					nfsd_net_id));
1003 		host_err = vfs_iter_write(file, &iter, &pos, flags);
1004 		up_read(&nf->nf_rwsem);
1005 	}
1006 	if (host_err < 0) {
1007 		nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1008 					 nfsd_net_id));
1009 		goto out_nfserr;
1010 	}
1011 	*cnt = host_err;
1012 	nfsd_stats_io_write_add(exp, *cnt);
1013 	fsnotify_modify(file);
1014 
1015 	if (stable && use_wgather) {
1016 		host_err = wait_for_concurrent_writes(file);
1017 		if (host_err < 0)
1018 			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1019 						 nfsd_net_id));
1020 	}
1021 
1022 out_nfserr:
1023 	if (host_err >= 0) {
1024 		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1025 		nfserr = nfs_ok;
1026 	} else {
1027 		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1028 		nfserr = nfserrno(host_err);
1029 	}
1030 	if (restore_flags)
1031 		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1032 	return nfserr;
1033 }
1034 
1035 /*
1036  * Read data from a file. count must contain the requested read count
1037  * on entry. On return, *count contains the number of bytes actually read.
1038  * N.B. After this call fhp needs an fh_put
1039  */
1040 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1041 	loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
1042 	u32 *eof)
1043 {
1044 	struct nfsd_file	*nf;
1045 	struct file *file;
1046 	__be32 err;
1047 
1048 	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1049 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
1050 	if (err)
1051 		return err;
1052 
1053 	file = nf->nf_file;
1054 	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1055 		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1056 	else
1057 		err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
1058 
1059 	nfsd_file_put(nf);
1060 
1061 	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1062 
1063 	return err;
1064 }
1065 
1066 /*
1067  * Write data to a file.
1068  * The stable flag requests synchronous writes.
1069  * N.B. After this call fhp needs an fh_put
1070  */
1071 __be32
1072 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1073 	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1074 	   __be32 *verf)
1075 {
1076 	struct nfsd_file *nf;
1077 	__be32 err;
1078 
1079 	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1080 
1081 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1082 	if (err)
1083 		goto out;
1084 
1085 	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1086 			vlen, cnt, stable, verf);
1087 	nfsd_file_put(nf);
1088 out:
1089 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1090 	return err;
1091 }
1092 
1093 #ifdef CONFIG_NFSD_V3
1094 static int
1095 nfsd_filemap_write_and_wait_range(struct nfsd_file *nf, loff_t offset,
1096 				  loff_t end)
1097 {
1098 	struct address_space *mapping = nf->nf_file->f_mapping;
1099 	int ret = filemap_fdatawrite_range(mapping, offset, end);
1100 
1101 	if (ret)
1102 		return ret;
1103 	filemap_fdatawait_range_keep_errors(mapping, offset, end);
1104 	return 0;
1105 }
1106 
1107 /*
1108  * Commit all pending writes to stable storage.
1109  *
1110  * Note: we only guarantee that data that lies within the range specified
1111  * by the 'offset' and 'count' parameters will be synced.
1112  *
1113  * Unfortunately we cannot lock the file to make sure we return full WCC
1114  * data to the client, as locking happens lower down in the filesystem.
1115  */
1116 __be32
1117 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
1118                loff_t offset, unsigned long count, __be32 *verf)
1119 {
1120 	struct nfsd_file	*nf;
1121 	loff_t			end = LLONG_MAX;
1122 	__be32			err = nfserr_inval;
1123 
1124 	if (offset < 0)
1125 		goto out;
1126 	if (count != 0) {
1127 		end = offset + (loff_t)count - 1;
1128 		if (end < offset)
1129 			goto out;
1130 	}
1131 
1132 	err = nfsd_file_acquire(rqstp, fhp,
1133 			NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
1134 	if (err)
1135 		goto out;
1136 	if (EX_ISSYNC(fhp->fh_export)) {
1137 		int err2 = nfsd_filemap_write_and_wait_range(nf, offset, end);
1138 
1139 		down_write(&nf->nf_rwsem);
1140 		if (!err2)
1141 			err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
1142 		switch (err2) {
1143 		case 0:
1144 			nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1145 						nfsd_net_id));
1146 			break;
1147 		case -EINVAL:
1148 			err = nfserr_notsupp;
1149 			break;
1150 		default:
1151 			err = nfserrno(err2);
1152 			nfsd_reset_boot_verifier(net_generic(nf->nf_net,
1153 						 nfsd_net_id));
1154 		}
1155 		up_write(&nf->nf_rwsem);
1156 	} else
1157 		nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1158 					nfsd_net_id));
1159 
1160 	nfsd_file_put(nf);
1161 out:
1162 	return err;
1163 }
1164 #endif /* CONFIG_NFSD_V3 */
1165 
1166 static __be32
1167 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *resfhp,
1168 			struct iattr *iap)
1169 {
1170 	/*
1171 	 * Mode has already been set earlier in create:
1172 	 */
1173 	iap->ia_valid &= ~ATTR_MODE;
1174 	/*
1175 	 * Setting uid/gid works only for root.  Irix appears to
1176 	 * send along the gid on create when it tries to implement
1177 	 * setgid directories via NFS:
1178 	 */
1179 	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1180 		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1181 	if (iap->ia_valid)
1182 		return nfsd_setattr(rqstp, resfhp, iap, 0, (time64_t)0);
1183 	/* Callers expect file metadata to be committed here */
1184 	return nfserrno(commit_metadata(resfhp));
1185 }
1186 
1187 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1188  * setting size to 0 may fail for some specific file systems by the permission
1189  * checking which requires WRITE permission but the mode is 000.
1190  * we ignore the resizing(to 0) on the just new created file, since the size is
1191  * 0 after file created.
1192  *
1193  * call this only after vfs_create() is called.
1194  * */
1195 static void
1196 nfsd_check_ignore_resizing(struct iattr *iap)
1197 {
1198 	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1199 		iap->ia_valid &= ~ATTR_SIZE;
1200 }
1201 
1202 /* The parent directory should already be locked: */
1203 __be32
1204 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1205 		char *fname, int flen, struct iattr *iap,
1206 		int type, dev_t rdev, struct svc_fh *resfhp)
1207 {
1208 	struct dentry	*dentry, *dchild;
1209 	struct inode	*dirp;
1210 	__be32		err;
1211 	__be32		err2;
1212 	int		host_err;
1213 
1214 	dentry = fhp->fh_dentry;
1215 	dirp = d_inode(dentry);
1216 
1217 	dchild = dget(resfhp->fh_dentry);
1218 	if (!fhp->fh_locked) {
1219 		WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
1220 				dentry);
1221 		err = nfserr_io;
1222 		goto out;
1223 	}
1224 
1225 	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1226 	if (err)
1227 		goto out;
1228 
1229 	if (!(iap->ia_valid & ATTR_MODE))
1230 		iap->ia_mode = 0;
1231 	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1232 
1233 	if (!IS_POSIXACL(dirp))
1234 		iap->ia_mode &= ~current_umask();
1235 
1236 	err = 0;
1237 	host_err = 0;
1238 	switch (type) {
1239 	case S_IFREG:
1240 		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1241 		if (!host_err)
1242 			nfsd_check_ignore_resizing(iap);
1243 		break;
1244 	case S_IFDIR:
1245 		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
1246 		if (!host_err && unlikely(d_unhashed(dchild))) {
1247 			struct dentry *d;
1248 			d = lookup_one_len(dchild->d_name.name,
1249 					   dchild->d_parent,
1250 					   dchild->d_name.len);
1251 			if (IS_ERR(d)) {
1252 				host_err = PTR_ERR(d);
1253 				break;
1254 			}
1255 			if (unlikely(d_is_negative(d))) {
1256 				dput(d);
1257 				err = nfserr_serverfault;
1258 				goto out;
1259 			}
1260 			dput(resfhp->fh_dentry);
1261 			resfhp->fh_dentry = dget(d);
1262 			err = fh_update(resfhp);
1263 			dput(dchild);
1264 			dchild = d;
1265 			if (err)
1266 				goto out;
1267 		}
1268 		break;
1269 	case S_IFCHR:
1270 	case S_IFBLK:
1271 	case S_IFIFO:
1272 	case S_IFSOCK:
1273 		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
1274 				     iap->ia_mode, rdev);
1275 		break;
1276 	default:
1277 		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1278 		       type);
1279 		host_err = -EINVAL;
1280 	}
1281 	if (host_err < 0)
1282 		goto out_nfserr;
1283 
1284 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1285 
1286 	/*
1287 	 * nfsd_create_setattr already committed the child.  Transactional
1288 	 * filesystems had a chance to commit changes for both parent and
1289 	 * child simultaneously making the following commit_metadata a
1290 	 * noop.
1291 	 */
1292 	err2 = nfserrno(commit_metadata(fhp));
1293 	if (err2)
1294 		err = err2;
1295 	/*
1296 	 * Update the file handle to get the new inode info.
1297 	 */
1298 	if (!err)
1299 		err = fh_update(resfhp);
1300 out:
1301 	dput(dchild);
1302 	return err;
1303 
1304 out_nfserr:
1305 	err = nfserrno(host_err);
1306 	goto out;
1307 }
1308 
1309 /*
1310  * Create a filesystem object (regular, directory, special).
1311  * Note that the parent directory is left locked.
1312  *
1313  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1314  */
1315 __be32
1316 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1317 		char *fname, int flen, struct iattr *iap,
1318 		int type, dev_t rdev, struct svc_fh *resfhp)
1319 {
1320 	struct dentry	*dentry, *dchild = NULL;
1321 	__be32		err;
1322 	int		host_err;
1323 
1324 	if (isdotent(fname, flen))
1325 		return nfserr_exist;
1326 
1327 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1328 	if (err)
1329 		return err;
1330 
1331 	dentry = fhp->fh_dentry;
1332 
1333 	host_err = fh_want_write(fhp);
1334 	if (host_err)
1335 		return nfserrno(host_err);
1336 
1337 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1338 	dchild = lookup_one_len(fname, dentry, flen);
1339 	host_err = PTR_ERR(dchild);
1340 	if (IS_ERR(dchild))
1341 		return nfserrno(host_err);
1342 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1343 	/*
1344 	 * We unconditionally drop our ref to dchild as fh_compose will have
1345 	 * already grabbed its own ref for it.
1346 	 */
1347 	dput(dchild);
1348 	if (err)
1349 		return err;
1350 	return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
1351 					rdev, resfhp);
1352 }
1353 
1354 #ifdef CONFIG_NFSD_V3
1355 
1356 /*
1357  * NFSv3 and NFSv4 version of nfsd_create
1358  */
1359 __be32
1360 do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1361 		char *fname, int flen, struct iattr *iap,
1362 		struct svc_fh *resfhp, int createmode, u32 *verifier,
1363 	        bool *truncp, bool *created)
1364 {
1365 	struct dentry	*dentry, *dchild = NULL;
1366 	struct inode	*dirp;
1367 	__be32		err;
1368 	int		host_err;
1369 	__u32		v_mtime=0, v_atime=0;
1370 
1371 	err = nfserr_perm;
1372 	if (!flen)
1373 		goto out;
1374 	err = nfserr_exist;
1375 	if (isdotent(fname, flen))
1376 		goto out;
1377 	if (!(iap->ia_valid & ATTR_MODE))
1378 		iap->ia_mode = 0;
1379 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
1380 	if (err)
1381 		goto out;
1382 
1383 	dentry = fhp->fh_dentry;
1384 	dirp = d_inode(dentry);
1385 
1386 	host_err = fh_want_write(fhp);
1387 	if (host_err)
1388 		goto out_nfserr;
1389 
1390 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1391 
1392 	/*
1393 	 * Compose the response file handle.
1394 	 */
1395 	dchild = lookup_one_len(fname, dentry, flen);
1396 	host_err = PTR_ERR(dchild);
1397 	if (IS_ERR(dchild))
1398 		goto out_nfserr;
1399 
1400 	/* If file doesn't exist, check for permissions to create one */
1401 	if (d_really_is_negative(dchild)) {
1402 		err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1403 		if (err)
1404 			goto out;
1405 	}
1406 
1407 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1408 	if (err)
1409 		goto out;
1410 
1411 	if (nfsd_create_is_exclusive(createmode)) {
1412 		/* solaris7 gets confused (bugid 4218508) if these have
1413 		 * the high bit set, so just clear the high bits. If this is
1414 		 * ever changed to use different attrs for storing the
1415 		 * verifier, then do_open_lookup() will also need to be fixed
1416 		 * accordingly.
1417 		 */
1418 		v_mtime = verifier[0]&0x7fffffff;
1419 		v_atime = verifier[1]&0x7fffffff;
1420 	}
1421 
1422 	if (d_really_is_positive(dchild)) {
1423 		err = 0;
1424 
1425 		switch (createmode) {
1426 		case NFS3_CREATE_UNCHECKED:
1427 			if (! d_is_reg(dchild))
1428 				goto out;
1429 			else if (truncp) {
1430 				/* in nfsv4, we need to treat this case a little
1431 				 * differently.  we don't want to truncate the
1432 				 * file now; this would be wrong if the OPEN
1433 				 * fails for some other reason.  furthermore,
1434 				 * if the size is nonzero, we should ignore it
1435 				 * according to spec!
1436 				 */
1437 				*truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
1438 			}
1439 			else {
1440 				iap->ia_valid &= ATTR_SIZE;
1441 				goto set_attr;
1442 			}
1443 			break;
1444 		case NFS3_CREATE_EXCLUSIVE:
1445 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1446 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1447 			    && d_inode(dchild)->i_size  == 0 ) {
1448 				if (created)
1449 					*created = true;
1450 				break;
1451 			}
1452 			fallthrough;
1453 		case NFS4_CREATE_EXCLUSIVE4_1:
1454 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1455 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1456 			    && d_inode(dchild)->i_size  == 0 ) {
1457 				if (created)
1458 					*created = true;
1459 				goto set_attr;
1460 			}
1461 			fallthrough;
1462 		case NFS3_CREATE_GUARDED:
1463 			err = nfserr_exist;
1464 		}
1465 		fh_drop_write(fhp);
1466 		goto out;
1467 	}
1468 
1469 	if (!IS_POSIXACL(dirp))
1470 		iap->ia_mode &= ~current_umask();
1471 
1472 	host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1473 	if (host_err < 0) {
1474 		fh_drop_write(fhp);
1475 		goto out_nfserr;
1476 	}
1477 	if (created)
1478 		*created = true;
1479 
1480 	nfsd_check_ignore_resizing(iap);
1481 
1482 	if (nfsd_create_is_exclusive(createmode)) {
1483 		/* Cram the verifier into atime/mtime */
1484 		iap->ia_valid = ATTR_MTIME|ATTR_ATIME
1485 			| ATTR_MTIME_SET|ATTR_ATIME_SET;
1486 		/* XXX someone who knows this better please fix it for nsec */
1487 		iap->ia_mtime.tv_sec = v_mtime;
1488 		iap->ia_atime.tv_sec = v_atime;
1489 		iap->ia_mtime.tv_nsec = 0;
1490 		iap->ia_atime.tv_nsec = 0;
1491 	}
1492 
1493  set_attr:
1494 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1495 
1496 	/*
1497 	 * nfsd_create_setattr already committed the child
1498 	 * (and possibly also the parent).
1499 	 */
1500 	if (!err)
1501 		err = nfserrno(commit_metadata(fhp));
1502 
1503 	/*
1504 	 * Update the filehandle to get the new inode info.
1505 	 */
1506 	if (!err)
1507 		err = fh_update(resfhp);
1508 
1509  out:
1510 	fh_unlock(fhp);
1511 	if (dchild && !IS_ERR(dchild))
1512 		dput(dchild);
1513 	fh_drop_write(fhp);
1514  	return err;
1515 
1516  out_nfserr:
1517 	err = nfserrno(host_err);
1518 	goto out;
1519 }
1520 #endif /* CONFIG_NFSD_V3 */
1521 
1522 /*
1523  * Read a symlink. On entry, *lenp must contain the maximum path length that
1524  * fits into the buffer. On return, it contains the true length.
1525  * N.B. After this call fhp needs an fh_put
1526  */
1527 __be32
1528 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1529 {
1530 	__be32		err;
1531 	const char *link;
1532 	struct path path;
1533 	DEFINE_DELAYED_CALL(done);
1534 	int len;
1535 
1536 	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1537 	if (unlikely(err))
1538 		return err;
1539 
1540 	path.mnt = fhp->fh_export->ex_path.mnt;
1541 	path.dentry = fhp->fh_dentry;
1542 
1543 	if (unlikely(!d_is_symlink(path.dentry)))
1544 		return nfserr_inval;
1545 
1546 	touch_atime(&path);
1547 
1548 	link = vfs_get_link(path.dentry, &done);
1549 	if (IS_ERR(link))
1550 		return nfserrno(PTR_ERR(link));
1551 
1552 	len = strlen(link);
1553 	if (len < *lenp)
1554 		*lenp = len;
1555 	memcpy(buf, link, *lenp);
1556 	do_delayed_call(&done);
1557 	return 0;
1558 }
1559 
1560 /*
1561  * Create a symlink and look up its inode
1562  * N.B. After this call _both_ fhp and resfhp need an fh_put
1563  */
1564 __be32
1565 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1566 				char *fname, int flen,
1567 				char *path,
1568 				struct svc_fh *resfhp)
1569 {
1570 	struct dentry	*dentry, *dnew;
1571 	__be32		err, cerr;
1572 	int		host_err;
1573 
1574 	err = nfserr_noent;
1575 	if (!flen || path[0] == '\0')
1576 		goto out;
1577 	err = nfserr_exist;
1578 	if (isdotent(fname, flen))
1579 		goto out;
1580 
1581 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1582 	if (err)
1583 		goto out;
1584 
1585 	host_err = fh_want_write(fhp);
1586 	if (host_err)
1587 		goto out_nfserr;
1588 
1589 	fh_lock(fhp);
1590 	dentry = fhp->fh_dentry;
1591 	dnew = lookup_one_len(fname, dentry, flen);
1592 	host_err = PTR_ERR(dnew);
1593 	if (IS_ERR(dnew))
1594 		goto out_nfserr;
1595 
1596 	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
1597 	err = nfserrno(host_err);
1598 	fh_unlock(fhp);
1599 	if (!err)
1600 		err = nfserrno(commit_metadata(fhp));
1601 
1602 	fh_drop_write(fhp);
1603 
1604 	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1605 	dput(dnew);
1606 	if (err==0) err = cerr;
1607 out:
1608 	return err;
1609 
1610 out_nfserr:
1611 	err = nfserrno(host_err);
1612 	goto out;
1613 }
1614 
1615 /*
1616  * Create a hardlink
1617  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1618  */
1619 __be32
1620 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1621 				char *name, int len, struct svc_fh *tfhp)
1622 {
1623 	struct dentry	*ddir, *dnew, *dold;
1624 	struct inode	*dirp;
1625 	__be32		err;
1626 	int		host_err;
1627 
1628 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1629 	if (err)
1630 		goto out;
1631 	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1632 	if (err)
1633 		goto out;
1634 	err = nfserr_isdir;
1635 	if (d_is_dir(tfhp->fh_dentry))
1636 		goto out;
1637 	err = nfserr_perm;
1638 	if (!len)
1639 		goto out;
1640 	err = nfserr_exist;
1641 	if (isdotent(name, len))
1642 		goto out;
1643 
1644 	host_err = fh_want_write(tfhp);
1645 	if (host_err) {
1646 		err = nfserrno(host_err);
1647 		goto out;
1648 	}
1649 
1650 	fh_lock_nested(ffhp, I_MUTEX_PARENT);
1651 	ddir = ffhp->fh_dentry;
1652 	dirp = d_inode(ddir);
1653 
1654 	dnew = lookup_one_len(name, ddir, len);
1655 	host_err = PTR_ERR(dnew);
1656 	if (IS_ERR(dnew))
1657 		goto out_nfserr;
1658 
1659 	dold = tfhp->fh_dentry;
1660 
1661 	err = nfserr_noent;
1662 	if (d_really_is_negative(dold))
1663 		goto out_dput;
1664 	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
1665 	fh_unlock(ffhp);
1666 	if (!host_err) {
1667 		err = nfserrno(commit_metadata(ffhp));
1668 		if (!err)
1669 			err = nfserrno(commit_metadata(tfhp));
1670 	} else {
1671 		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1672 			err = nfserr_acces;
1673 		else
1674 			err = nfserrno(host_err);
1675 	}
1676 out_dput:
1677 	dput(dnew);
1678 out_unlock:
1679 	fh_unlock(ffhp);
1680 	fh_drop_write(tfhp);
1681 out:
1682 	return err;
1683 
1684 out_nfserr:
1685 	err = nfserrno(host_err);
1686 	goto out_unlock;
1687 }
1688 
1689 static void
1690 nfsd_close_cached_files(struct dentry *dentry)
1691 {
1692 	struct inode *inode = d_inode(dentry);
1693 
1694 	if (inode && S_ISREG(inode->i_mode))
1695 		nfsd_file_close_inode_sync(inode);
1696 }
1697 
1698 static bool
1699 nfsd_has_cached_files(struct dentry *dentry)
1700 {
1701 	bool		ret = false;
1702 	struct inode *inode = d_inode(dentry);
1703 
1704 	if (inode && S_ISREG(inode->i_mode))
1705 		ret = nfsd_file_is_cached(inode);
1706 	return ret;
1707 }
1708 
1709 /*
1710  * Rename a file
1711  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1712  */
1713 __be32
1714 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1715 			    struct svc_fh *tfhp, char *tname, int tlen)
1716 {
1717 	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1718 	struct inode	*fdir, *tdir;
1719 	__be32		err;
1720 	int		host_err;
1721 	bool		close_cached = false;
1722 
1723 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1724 	if (err)
1725 		goto out;
1726 	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1727 	if (err)
1728 		goto out;
1729 
1730 	fdentry = ffhp->fh_dentry;
1731 	fdir = d_inode(fdentry);
1732 
1733 	tdentry = tfhp->fh_dentry;
1734 	tdir = d_inode(tdentry);
1735 
1736 	err = nfserr_perm;
1737 	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1738 		goto out;
1739 
1740 retry:
1741 	host_err = fh_want_write(ffhp);
1742 	if (host_err) {
1743 		err = nfserrno(host_err);
1744 		goto out;
1745 	}
1746 
1747 	/* cannot use fh_lock as we need deadlock protective ordering
1748 	 * so do it by hand */
1749 	trap = lock_rename(tdentry, fdentry);
1750 	ffhp->fh_locked = tfhp->fh_locked = true;
1751 	fill_pre_wcc(ffhp);
1752 	fill_pre_wcc(tfhp);
1753 
1754 	odentry = lookup_one_len(fname, fdentry, flen);
1755 	host_err = PTR_ERR(odentry);
1756 	if (IS_ERR(odentry))
1757 		goto out_nfserr;
1758 
1759 	host_err = -ENOENT;
1760 	if (d_really_is_negative(odentry))
1761 		goto out_dput_old;
1762 	host_err = -EINVAL;
1763 	if (odentry == trap)
1764 		goto out_dput_old;
1765 
1766 	ndentry = lookup_one_len(tname, tdentry, tlen);
1767 	host_err = PTR_ERR(ndentry);
1768 	if (IS_ERR(ndentry))
1769 		goto out_dput_old;
1770 	host_err = -ENOTEMPTY;
1771 	if (ndentry == trap)
1772 		goto out_dput_new;
1773 
1774 	host_err = -EXDEV;
1775 	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1776 		goto out_dput_new;
1777 	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1778 		goto out_dput_new;
1779 
1780 	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1781 	    nfsd_has_cached_files(ndentry)) {
1782 		close_cached = true;
1783 		goto out_dput_old;
1784 	} else {
1785 		struct renamedata rd = {
1786 			.old_mnt_userns	= &init_user_ns,
1787 			.old_dir	= fdir,
1788 			.old_dentry	= odentry,
1789 			.new_mnt_userns	= &init_user_ns,
1790 			.new_dir	= tdir,
1791 			.new_dentry	= ndentry,
1792 		};
1793 		host_err = vfs_rename(&rd);
1794 		if (!host_err) {
1795 			host_err = commit_metadata(tfhp);
1796 			if (!host_err)
1797 				host_err = commit_metadata(ffhp);
1798 		}
1799 	}
1800  out_dput_new:
1801 	dput(ndentry);
1802  out_dput_old:
1803 	dput(odentry);
1804  out_nfserr:
1805 	err = nfserrno(host_err);
1806 	/*
1807 	 * We cannot rely on fh_unlock on the two filehandles,
1808 	 * as that would do the wrong thing if the two directories
1809 	 * were the same, so again we do it by hand.
1810 	 */
1811 	if (!close_cached) {
1812 		fill_post_wcc(ffhp);
1813 		fill_post_wcc(tfhp);
1814 	}
1815 	unlock_rename(tdentry, fdentry);
1816 	ffhp->fh_locked = tfhp->fh_locked = false;
1817 	fh_drop_write(ffhp);
1818 
1819 	/*
1820 	 * If the target dentry has cached open files, then we need to try to
1821 	 * close them prior to doing the rename. Flushing delayed fput
1822 	 * shouldn't be done with locks held however, so we delay it until this
1823 	 * point and then reattempt the whole shebang.
1824 	 */
1825 	if (close_cached) {
1826 		close_cached = false;
1827 		nfsd_close_cached_files(ndentry);
1828 		dput(ndentry);
1829 		goto retry;
1830 	}
1831 out:
1832 	return err;
1833 }
1834 
1835 /*
1836  * Unlink a file or directory
1837  * N.B. After this call fhp needs an fh_put
1838  */
1839 __be32
1840 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1841 				char *fname, int flen)
1842 {
1843 	struct dentry	*dentry, *rdentry;
1844 	struct inode	*dirp;
1845 	struct inode	*rinode;
1846 	__be32		err;
1847 	int		host_err;
1848 
1849 	err = nfserr_acces;
1850 	if (!flen || isdotent(fname, flen))
1851 		goto out;
1852 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1853 	if (err)
1854 		goto out;
1855 
1856 	host_err = fh_want_write(fhp);
1857 	if (host_err)
1858 		goto out_nfserr;
1859 
1860 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1861 	dentry = fhp->fh_dentry;
1862 	dirp = d_inode(dentry);
1863 
1864 	rdentry = lookup_one_len(fname, dentry, flen);
1865 	host_err = PTR_ERR(rdentry);
1866 	if (IS_ERR(rdentry))
1867 		goto out_drop_write;
1868 
1869 	if (d_really_is_negative(rdentry)) {
1870 		dput(rdentry);
1871 		host_err = -ENOENT;
1872 		goto out_drop_write;
1873 	}
1874 	rinode = d_inode(rdentry);
1875 	ihold(rinode);
1876 
1877 	if (!type)
1878 		type = d_inode(rdentry)->i_mode & S_IFMT;
1879 
1880 	if (type != S_IFDIR) {
1881 		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1882 			nfsd_close_cached_files(rdentry);
1883 		host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
1884 	} else {
1885 		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
1886 	}
1887 
1888 	fh_unlock(fhp);
1889 	if (!host_err)
1890 		host_err = commit_metadata(fhp);
1891 	dput(rdentry);
1892 	iput(rinode);    /* truncate the inode here */
1893 
1894 out_drop_write:
1895 	fh_drop_write(fhp);
1896 out_nfserr:
1897 	if (host_err == -EBUSY) {
1898 		/* name is mounted-on. There is no perfect
1899 		 * error status.
1900 		 */
1901 		if (nfsd_v4client(rqstp))
1902 			err = nfserr_file_open;
1903 		else
1904 			err = nfserr_acces;
1905 	} else {
1906 		err = nfserrno(host_err);
1907 	}
1908 out:
1909 	return err;
1910 }
1911 
1912 /*
1913  * We do this buffering because we must not call back into the file
1914  * system's ->lookup() method from the filldir callback. That may well
1915  * deadlock a number of file systems.
1916  *
1917  * This is based heavily on the implementation of same in XFS.
1918  */
1919 struct buffered_dirent {
1920 	u64		ino;
1921 	loff_t		offset;
1922 	int		namlen;
1923 	unsigned int	d_type;
1924 	char		name[];
1925 };
1926 
1927 struct readdir_data {
1928 	struct dir_context ctx;
1929 	char		*dirent;
1930 	size_t		used;
1931 	int		full;
1932 };
1933 
1934 static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1935 				 int namlen, loff_t offset, u64 ino,
1936 				 unsigned int d_type)
1937 {
1938 	struct readdir_data *buf =
1939 		container_of(ctx, struct readdir_data, ctx);
1940 	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1941 	unsigned int reclen;
1942 
1943 	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1944 	if (buf->used + reclen > PAGE_SIZE) {
1945 		buf->full = 1;
1946 		return -EINVAL;
1947 	}
1948 
1949 	de->namlen = namlen;
1950 	de->offset = offset;
1951 	de->ino = ino;
1952 	de->d_type = d_type;
1953 	memcpy(de->name, name, namlen);
1954 	buf->used += reclen;
1955 
1956 	return 0;
1957 }
1958 
1959 static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
1960 				    nfsd_filldir_t func, struct readdir_cd *cdp,
1961 				    loff_t *offsetp)
1962 {
1963 	struct buffered_dirent *de;
1964 	int host_err;
1965 	int size;
1966 	loff_t offset;
1967 	struct readdir_data buf = {
1968 		.ctx.actor = nfsd_buffered_filldir,
1969 		.dirent = (void *)__get_free_page(GFP_KERNEL)
1970 	};
1971 
1972 	if (!buf.dirent)
1973 		return nfserrno(-ENOMEM);
1974 
1975 	offset = *offsetp;
1976 
1977 	while (1) {
1978 		unsigned int reclen;
1979 
1980 		cdp->err = nfserr_eof; /* will be cleared on successful read */
1981 		buf.used = 0;
1982 		buf.full = 0;
1983 
1984 		host_err = iterate_dir(file, &buf.ctx);
1985 		if (buf.full)
1986 			host_err = 0;
1987 
1988 		if (host_err < 0)
1989 			break;
1990 
1991 		size = buf.used;
1992 
1993 		if (!size)
1994 			break;
1995 
1996 		de = (struct buffered_dirent *)buf.dirent;
1997 		while (size > 0) {
1998 			offset = de->offset;
1999 
2000 			if (func(cdp, de->name, de->namlen, de->offset,
2001 				 de->ino, de->d_type))
2002 				break;
2003 
2004 			if (cdp->err != nfs_ok)
2005 				break;
2006 
2007 			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
2008 
2009 			reclen = ALIGN(sizeof(*de) + de->namlen,
2010 				       sizeof(u64));
2011 			size -= reclen;
2012 			de = (struct buffered_dirent *)((char *)de + reclen);
2013 		}
2014 		if (size > 0) /* We bailed out early */
2015 			break;
2016 
2017 		offset = vfs_llseek(file, 0, SEEK_CUR);
2018 	}
2019 
2020 	free_page((unsigned long)(buf.dirent));
2021 
2022 	if (host_err)
2023 		return nfserrno(host_err);
2024 
2025 	*offsetp = offset;
2026 	return cdp->err;
2027 }
2028 
2029 /*
2030  * Read entries from a directory.
2031  * The  NFSv3/4 verifier we ignore for now.
2032  */
2033 __be32
2034 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2035 	     struct readdir_cd *cdp, nfsd_filldir_t func)
2036 {
2037 	__be32		err;
2038 	struct file	*file;
2039 	loff_t		offset = *offsetp;
2040 	int             may_flags = NFSD_MAY_READ;
2041 
2042 	/* NFSv2 only supports 32 bit cookies */
2043 	if (rqstp->rq_vers > 2)
2044 		may_flags |= NFSD_MAY_64BIT_COOKIE;
2045 
2046 	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2047 	if (err)
2048 		goto out;
2049 
2050 	offset = vfs_llseek(file, offset, SEEK_SET);
2051 	if (offset < 0) {
2052 		err = nfserrno((int)offset);
2053 		goto out_close;
2054 	}
2055 
2056 	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2057 
2058 	if (err == nfserr_eof || err == nfserr_toosmall)
2059 		err = nfs_ok; /* can still be found in ->err */
2060 out_close:
2061 	fput(file);
2062 out:
2063 	return err;
2064 }
2065 
2066 /*
2067  * Get file system stats
2068  * N.B. After this call fhp needs an fh_put
2069  */
2070 __be32
2071 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2072 {
2073 	__be32 err;
2074 
2075 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2076 	if (!err) {
2077 		struct path path = {
2078 			.mnt	= fhp->fh_export->ex_path.mnt,
2079 			.dentry	= fhp->fh_dentry,
2080 		};
2081 		if (vfs_statfs(&path, stat))
2082 			err = nfserr_io;
2083 	}
2084 	return err;
2085 }
2086 
2087 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2088 {
2089 	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2090 }
2091 
2092 #ifdef CONFIG_NFSD_V4
2093 /*
2094  * Helper function to translate error numbers. In the case of xattr operations,
2095  * some error codes need to be translated outside of the standard translations.
2096  *
2097  * ENODATA needs to be translated to nfserr_noxattr.
2098  * E2BIG to nfserr_xattr2big.
2099  *
2100  * Additionally, vfs_listxattr can return -ERANGE. This means that the
2101  * file has too many extended attributes to retrieve inside an
2102  * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2103  * filesystems will allow the adding of extended attributes until they hit
2104  * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2105  * So, at that point, the attributes are present and valid, but can't
2106  * be retrieved using listxattr, since the upper level xattr code enforces
2107  * the XATTR_LIST_MAX limit.
2108  *
2109  * This bug means that we need to deal with listxattr returning -ERANGE. The
2110  * best mapping is to return TOOSMALL.
2111  */
2112 static __be32
2113 nfsd_xattr_errno(int err)
2114 {
2115 	switch (err) {
2116 	case -ENODATA:
2117 		return nfserr_noxattr;
2118 	case -E2BIG:
2119 		return nfserr_xattr2big;
2120 	case -ERANGE:
2121 		return nfserr_toosmall;
2122 	}
2123 	return nfserrno(err);
2124 }
2125 
2126 /*
2127  * Retrieve the specified user extended attribute. To avoid always
2128  * having to allocate the maximum size (since we are not getting
2129  * a maximum size from the RPC), do a probe + alloc. Hold a reader
2130  * lock on i_rwsem to prevent the extended attribute from changing
2131  * size while we're doing this.
2132  */
2133 __be32
2134 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2135 	      void **bufp, int *lenp)
2136 {
2137 	ssize_t len;
2138 	__be32 err;
2139 	char *buf;
2140 	struct inode *inode;
2141 	struct dentry *dentry;
2142 
2143 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2144 	if (err)
2145 		return err;
2146 
2147 	err = nfs_ok;
2148 	dentry = fhp->fh_dentry;
2149 	inode = d_inode(dentry);
2150 
2151 	inode_lock_shared(inode);
2152 
2153 	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
2154 
2155 	/*
2156 	 * Zero-length attribute, just return.
2157 	 */
2158 	if (len == 0) {
2159 		*bufp = NULL;
2160 		*lenp = 0;
2161 		goto out;
2162 	}
2163 
2164 	if (len < 0) {
2165 		err = nfsd_xattr_errno(len);
2166 		goto out;
2167 	}
2168 
2169 	if (len > *lenp) {
2170 		err = nfserr_toosmall;
2171 		goto out;
2172 	}
2173 
2174 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2175 	if (buf == NULL) {
2176 		err = nfserr_jukebox;
2177 		goto out;
2178 	}
2179 
2180 	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
2181 	if (len <= 0) {
2182 		kvfree(buf);
2183 		buf = NULL;
2184 		err = nfsd_xattr_errno(len);
2185 	}
2186 
2187 	*lenp = len;
2188 	*bufp = buf;
2189 
2190 out:
2191 	inode_unlock_shared(inode);
2192 
2193 	return err;
2194 }
2195 
2196 /*
2197  * Retrieve the xattr names. Since we can't know how many are
2198  * user extended attributes, we must get all attributes here,
2199  * and have the XDR encode filter out the "user." ones.
2200  *
2201  * While this could always just allocate an XATTR_LIST_MAX
2202  * buffer, that's a waste, so do a probe + allocate. To
2203  * avoid any changes between the probe and allocate, wrap
2204  * this in inode_lock.
2205  */
2206 __be32
2207 nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2208 	       int *lenp)
2209 {
2210 	ssize_t len;
2211 	__be32 err;
2212 	char *buf;
2213 	struct inode *inode;
2214 	struct dentry *dentry;
2215 
2216 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2217 	if (err)
2218 		return err;
2219 
2220 	dentry = fhp->fh_dentry;
2221 	inode = d_inode(dentry);
2222 	*lenp = 0;
2223 
2224 	inode_lock_shared(inode);
2225 
2226 	len = vfs_listxattr(dentry, NULL, 0);
2227 	if (len <= 0) {
2228 		err = nfsd_xattr_errno(len);
2229 		goto out;
2230 	}
2231 
2232 	if (len > XATTR_LIST_MAX) {
2233 		err = nfserr_xattr2big;
2234 		goto out;
2235 	}
2236 
2237 	/*
2238 	 * We're holding i_rwsem - use GFP_NOFS.
2239 	 */
2240 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2241 	if (buf == NULL) {
2242 		err = nfserr_jukebox;
2243 		goto out;
2244 	}
2245 
2246 	len = vfs_listxattr(dentry, buf, len);
2247 	if (len <= 0) {
2248 		kvfree(buf);
2249 		err = nfsd_xattr_errno(len);
2250 		goto out;
2251 	}
2252 
2253 	*lenp = len;
2254 	*bufp = buf;
2255 
2256 	err = nfs_ok;
2257 out:
2258 	inode_unlock_shared(inode);
2259 
2260 	return err;
2261 }
2262 
2263 /*
2264  * Removexattr and setxattr need to call fh_lock to both lock the inode
2265  * and set the change attribute. Since the top-level vfs_removexattr
2266  * and vfs_setxattr calls already do their own inode_lock calls, call
2267  * the _locked variant. Pass in a NULL pointer for delegated_inode,
2268  * and let the client deal with NFS4ERR_DELAY (same as with e.g.
2269  * setattr and remove).
2270  */
2271 __be32
2272 nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2273 {
2274 	__be32 err;
2275 	int ret;
2276 
2277 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2278 	if (err)
2279 		return err;
2280 
2281 	ret = fh_want_write(fhp);
2282 	if (ret)
2283 		return nfserrno(ret);
2284 
2285 	fh_lock(fhp);
2286 
2287 	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
2288 				       name, NULL);
2289 
2290 	fh_unlock(fhp);
2291 	fh_drop_write(fhp);
2292 
2293 	return nfsd_xattr_errno(ret);
2294 }
2295 
2296 __be32
2297 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2298 	      void *buf, u32 len, u32 flags)
2299 {
2300 	__be32 err;
2301 	int ret;
2302 
2303 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2304 	if (err)
2305 		return err;
2306 
2307 	ret = fh_want_write(fhp);
2308 	if (ret)
2309 		return nfserrno(ret);
2310 	fh_lock(fhp);
2311 
2312 	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
2313 				    len, flags, NULL);
2314 
2315 	fh_unlock(fhp);
2316 	fh_drop_write(fhp);
2317 
2318 	return nfsd_xattr_errno(ret);
2319 }
2320 #endif
2321 
2322 /*
2323  * Check for a user's access permissions to this inode.
2324  */
2325 __be32
2326 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2327 					struct dentry *dentry, int acc)
2328 {
2329 	struct inode	*inode = d_inode(dentry);
2330 	int		err;
2331 
2332 	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2333 		return 0;
2334 #if 0
2335 	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2336 		acc,
2337 		(acc & NFSD_MAY_READ)?	" read"  : "",
2338 		(acc & NFSD_MAY_WRITE)?	" write" : "",
2339 		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2340 		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2341 		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2342 		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2343 		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2344 		inode->i_mode,
2345 		IS_IMMUTABLE(inode)?	" immut" : "",
2346 		IS_APPEND(inode)?	" append" : "",
2347 		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2348 	dprintk("      owner %d/%d user %d/%d\n",
2349 		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2350 #endif
2351 
2352 	/* Normally we reject any write/sattr etc access on a read-only file
2353 	 * system.  But if it is IRIX doing check on write-access for a
2354 	 * device special file, we ignore rofs.
2355 	 */
2356 	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2357 		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2358 			if (exp_rdonly(rqstp, exp) ||
2359 			    __mnt_is_readonly(exp->ex_path.mnt))
2360 				return nfserr_rofs;
2361 			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2362 				return nfserr_perm;
2363 		}
2364 	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2365 		return nfserr_perm;
2366 
2367 	if (acc & NFSD_MAY_LOCK) {
2368 		/* If we cannot rely on authentication in NLM requests,
2369 		 * just allow locks, otherwise require read permission, or
2370 		 * ownership
2371 		 */
2372 		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2373 			return 0;
2374 		else
2375 			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2376 	}
2377 	/*
2378 	 * The file owner always gets access permission for accesses that
2379 	 * would normally be checked at open time. This is to make
2380 	 * file access work even when the client has done a fchmod(fd, 0).
2381 	 *
2382 	 * However, `cp foo bar' should fail nevertheless when bar is
2383 	 * readonly. A sensible way to do this might be to reject all
2384 	 * attempts to truncate a read-only file, because a creat() call
2385 	 * always implies file truncation.
2386 	 * ... but this isn't really fair.  A process may reasonably call
2387 	 * ftruncate on an open file descriptor on a file with perm 000.
2388 	 * We must trust the client to do permission checking - using "ACCESS"
2389 	 * with NFSv3.
2390 	 */
2391 	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2392 	    uid_eq(inode->i_uid, current_fsuid()))
2393 		return 0;
2394 
2395 	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2396 	err = inode_permission(&init_user_ns, inode,
2397 			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2398 
2399 	/* Allow read access to binaries even when mode 111 */
2400 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2401 	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2402 	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2403 		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
2404 
2405 	return err? nfserrno(err) : 0;
2406 }
2407