xref: /linux/fs/nfsd/vfs.c (revision aaa44952bbd1d4db14a4d676bf9595bb5db7e7b0)
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  *      NeilBrown <neilb@cse.unsw.edu.au>
248  */
249 __be32
250 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
251 				unsigned int len, struct svc_fh *resfh)
252 {
253 	struct svc_export	*exp;
254 	struct dentry		*dentry;
255 	__be32 err;
256 
257 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
258 	if (err)
259 		return err;
260 	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
261 	if (err)
262 		return err;
263 	err = check_nfsd_access(exp, rqstp);
264 	if (err)
265 		goto out;
266 	/*
267 	 * Note: we compose the file handle now, but as the
268 	 * dentry may be negative, it may need to be updated.
269 	 */
270 	err = fh_compose(resfh, exp, dentry, fhp);
271 	if (!err && d_really_is_negative(dentry))
272 		err = nfserr_noent;
273 out:
274 	dput(dentry);
275 	exp_put(exp);
276 	return err;
277 }
278 
279 /*
280  * Commit metadata changes to stable storage.
281  */
282 static int
283 commit_inode_metadata(struct inode *inode)
284 {
285 	const struct export_operations *export_ops = inode->i_sb->s_export_op;
286 
287 	if (export_ops->commit_metadata)
288 		return export_ops->commit_metadata(inode);
289 	return sync_inode_metadata(inode, 1);
290 }
291 
292 static int
293 commit_metadata(struct svc_fh *fhp)
294 {
295 	struct inode *inode = d_inode(fhp->fh_dentry);
296 
297 	if (!EX_ISSYNC(fhp->fh_export))
298 		return 0;
299 	return commit_inode_metadata(inode);
300 }
301 
302 /*
303  * Go over the attributes and take care of the small differences between
304  * NFS semantics and what Linux expects.
305  */
306 static void
307 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
308 {
309 	/* sanitize the mode change */
310 	if (iap->ia_valid & ATTR_MODE) {
311 		iap->ia_mode &= S_IALLUGO;
312 		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
313 	}
314 
315 	/* Revoke setuid/setgid on chown */
316 	if (!S_ISDIR(inode->i_mode) &&
317 	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
318 		iap->ia_valid |= ATTR_KILL_PRIV;
319 		if (iap->ia_valid & ATTR_MODE) {
320 			/* we're setting mode too, just clear the s*id bits */
321 			iap->ia_mode &= ~S_ISUID;
322 			if (iap->ia_mode & S_IXGRP)
323 				iap->ia_mode &= ~S_ISGID;
324 		} else {
325 			/* set ATTR_KILL_* bits and let VFS handle it */
326 			iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
327 		}
328 	}
329 }
330 
331 static __be32
332 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
333 		struct iattr *iap)
334 {
335 	struct inode *inode = d_inode(fhp->fh_dentry);
336 	int host_err;
337 
338 	if (iap->ia_size < inode->i_size) {
339 		__be32 err;
340 
341 		err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
342 				NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
343 		if (err)
344 			return err;
345 	}
346 
347 	host_err = get_write_access(inode);
348 	if (host_err)
349 		goto out_nfserrno;
350 
351 	host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
352 	if (host_err)
353 		goto out_put_write_access;
354 	return 0;
355 
356 out_put_write_access:
357 	put_write_access(inode);
358 out_nfserrno:
359 	return nfserrno(host_err);
360 }
361 
362 /*
363  * Set various file attributes.  After this call fhp needs an fh_put.
364  */
365 __be32
366 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
367 	     int check_guard, time64_t guardtime)
368 {
369 	struct dentry	*dentry;
370 	struct inode	*inode;
371 	int		accmode = NFSD_MAY_SATTR;
372 	umode_t		ftype = 0;
373 	__be32		err;
374 	int		host_err;
375 	bool		get_write_count;
376 	bool		size_change = (iap->ia_valid & ATTR_SIZE);
377 
378 	if (iap->ia_valid & ATTR_SIZE) {
379 		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
380 		ftype = S_IFREG;
381 	}
382 
383 	/*
384 	 * If utimes(2) and friends are called with times not NULL, we should
385 	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
386 	 * will return EACCES, when the caller's effective UID does not match
387 	 * the owner of the file, and the caller is not privileged. In this
388 	 * situation, we should return EPERM(notify_change will return this).
389 	 */
390 	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
391 		accmode |= NFSD_MAY_OWNER_OVERRIDE;
392 		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
393 			accmode |= NFSD_MAY_WRITE;
394 	}
395 
396 	/* Callers that do fh_verify should do the fh_want_write: */
397 	get_write_count = !fhp->fh_dentry;
398 
399 	/* Get inode */
400 	err = fh_verify(rqstp, fhp, ftype, accmode);
401 	if (err)
402 		return err;
403 	if (get_write_count) {
404 		host_err = fh_want_write(fhp);
405 		if (host_err)
406 			goto out;
407 	}
408 
409 	dentry = fhp->fh_dentry;
410 	inode = d_inode(dentry);
411 
412 	/* Ignore any mode updates on symlinks */
413 	if (S_ISLNK(inode->i_mode))
414 		iap->ia_valid &= ~ATTR_MODE;
415 
416 	if (!iap->ia_valid)
417 		return 0;
418 
419 	nfsd_sanitize_attrs(inode, iap);
420 
421 	if (check_guard && guardtime != inode->i_ctime.tv_sec)
422 		return nfserr_notsync;
423 
424 	/*
425 	 * The size case is special, it changes the file in addition to the
426 	 * attributes, and file systems don't expect it to be mixed with
427 	 * "random" attribute changes.  We thus split out the size change
428 	 * into a separate call to ->setattr, and do the rest as a separate
429 	 * setattr call.
430 	 */
431 	if (size_change) {
432 		err = nfsd_get_write_access(rqstp, fhp, iap);
433 		if (err)
434 			return err;
435 	}
436 
437 	fh_lock(fhp);
438 	if (size_change) {
439 		/*
440 		 * RFC5661, Section 18.30.4:
441 		 *   Changing the size of a file with SETATTR indirectly
442 		 *   changes the time_modify and change attributes.
443 		 *
444 		 * (and similar for the older RFCs)
445 		 */
446 		struct iattr size_attr = {
447 			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
448 			.ia_size	= iap->ia_size,
449 		};
450 
451 		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
452 		if (host_err)
453 			goto out_unlock;
454 		iap->ia_valid &= ~ATTR_SIZE;
455 
456 		/*
457 		 * Avoid the additional setattr call below if the only other
458 		 * attribute that the client sends is the mtime, as we update
459 		 * it as part of the size change above.
460 		 */
461 		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
462 			goto out_unlock;
463 	}
464 
465 	iap->ia_valid |= ATTR_CTIME;
466 	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
467 
468 out_unlock:
469 	fh_unlock(fhp);
470 	if (size_change)
471 		put_write_access(inode);
472 out:
473 	if (!host_err)
474 		host_err = commit_metadata(fhp);
475 	return nfserrno(host_err);
476 }
477 
478 #if defined(CONFIG_NFSD_V4)
479 /*
480  * NFS junction information is stored in an extended attribute.
481  */
482 #define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
483 
484 /**
485  * nfsd4_is_junction - Test if an object could be an NFS junction
486  *
487  * @dentry: object to test
488  *
489  * Returns 1 if "dentry" appears to contain NFS junction information.
490  * Otherwise 0 is returned.
491  */
492 int nfsd4_is_junction(struct dentry *dentry)
493 {
494 	struct inode *inode = d_inode(dentry);
495 
496 	if (inode == NULL)
497 		return 0;
498 	if (inode->i_mode & S_IXUGO)
499 		return 0;
500 	if (!(inode->i_mode & S_ISVTX))
501 		return 0;
502 	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
503 			 NULL, 0) <= 0)
504 		return 0;
505 	return 1;
506 }
507 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
508 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
509 		struct xdr_netobj *label)
510 {
511 	__be32 error;
512 	int host_error;
513 	struct dentry *dentry;
514 
515 	error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
516 	if (error)
517 		return error;
518 
519 	dentry = fhp->fh_dentry;
520 
521 	inode_lock(d_inode(dentry));
522 	host_error = security_inode_setsecctx(dentry, label->data, label->len);
523 	inode_unlock(d_inode(dentry));
524 	return nfserrno(host_error);
525 }
526 #else
527 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
528 		struct xdr_netobj *label)
529 {
530 	return nfserr_notsupp;
531 }
532 #endif
533 
534 __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos,
535 		struct nfsd_file *nf_dst, u64 dst_pos, u64 count, bool sync)
536 {
537 	struct file *src = nf_src->nf_file;
538 	struct file *dst = nf_dst->nf_file;
539 	loff_t cloned;
540 	__be32 ret = 0;
541 
542 	down_write(&nf_dst->nf_rwsem);
543 	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
544 	if (cloned < 0) {
545 		ret = nfserrno(cloned);
546 		goto out_err;
547 	}
548 	if (count && cloned != count) {
549 		ret = nfserrno(-EINVAL);
550 		goto out_err;
551 	}
552 	if (sync) {
553 		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
554 		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
555 
556 		if (!status)
557 			status = commit_inode_metadata(file_inode(src));
558 		if (status < 0) {
559 			nfsd_reset_boot_verifier(net_generic(nf_dst->nf_net,
560 						 nfsd_net_id));
561 			ret = nfserrno(status);
562 		}
563 	}
564 out_err:
565 	up_write(&nf_dst->nf_rwsem);
566 	return ret;
567 }
568 
569 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
570 			     u64 dst_pos, u64 count)
571 {
572 
573 	/*
574 	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
575 	 * thread and client rpc slot.  The choice of 4MB is somewhat
576 	 * arbitrary.  We might instead base this on r/wsize, or make it
577 	 * tunable, or use a time instead of a byte limit, or implement
578 	 * asynchronous copy.  In theory a client could also recognize a
579 	 * limit like this and pipeline multiple COPY requests.
580 	 */
581 	count = min_t(u64, count, 1 << 22);
582 	return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
583 }
584 
585 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
586 			   struct file *file, loff_t offset, loff_t len,
587 			   int flags)
588 {
589 	int error;
590 
591 	if (!S_ISREG(file_inode(file)->i_mode))
592 		return nfserr_inval;
593 
594 	error = vfs_fallocate(file, flags, offset, len);
595 	if (!error)
596 		error = commit_metadata(fhp);
597 
598 	return nfserrno(error);
599 }
600 #endif /* defined(CONFIG_NFSD_V4) */
601 
602 #ifdef CONFIG_NFSD_V3
603 /*
604  * Check server access rights to a file system object
605  */
606 struct accessmap {
607 	u32		access;
608 	int		how;
609 };
610 static struct accessmap	nfs3_regaccess[] = {
611     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
612     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
613     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
614     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
615 
616 #ifdef CONFIG_NFSD_V4
617     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
618     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
619     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
620 #endif
621 
622     {	0,			0				}
623 };
624 
625 static struct accessmap	nfs3_diraccess[] = {
626     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
627     {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
628     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
629     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
630     {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
631 
632 #ifdef CONFIG_NFSD_V4
633     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
634     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
635     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
636 #endif
637 
638     {	0,			0				}
639 };
640 
641 static struct accessmap	nfs3_anyaccess[] = {
642 	/* Some clients - Solaris 2.6 at least, make an access call
643 	 * to the server to check for access for things like /dev/null
644 	 * (which really, the server doesn't care about).  So
645 	 * We provide simple access checking for them, looking
646 	 * mainly at mode bits, and we make sure to ignore read-only
647 	 * filesystem checks
648 	 */
649     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
650     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
651     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
652     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
653 
654     {	0,			0				}
655 };
656 
657 __be32
658 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
659 {
660 	struct accessmap	*map;
661 	struct svc_export	*export;
662 	struct dentry		*dentry;
663 	u32			query, result = 0, sresult = 0;
664 	__be32			error;
665 
666 	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
667 	if (error)
668 		goto out;
669 
670 	export = fhp->fh_export;
671 	dentry = fhp->fh_dentry;
672 
673 	if (d_is_reg(dentry))
674 		map = nfs3_regaccess;
675 	else if (d_is_dir(dentry))
676 		map = nfs3_diraccess;
677 	else
678 		map = nfs3_anyaccess;
679 
680 
681 	query = *access;
682 	for  (; map->access; map++) {
683 		if (map->access & query) {
684 			__be32 err2;
685 
686 			sresult |= map->access;
687 
688 			err2 = nfsd_permission(rqstp, export, dentry, map->how);
689 			switch (err2) {
690 			case nfs_ok:
691 				result |= map->access;
692 				break;
693 
694 			/* the following error codes just mean the access was not allowed,
695 			 * rather than an error occurred */
696 			case nfserr_rofs:
697 			case nfserr_acces:
698 			case nfserr_perm:
699 				/* simply don't "or" in the access bit. */
700 				break;
701 			default:
702 				error = err2;
703 				goto out;
704 			}
705 		}
706 	}
707 	*access = result;
708 	if (supported)
709 		*supported = sresult;
710 
711  out:
712 	return error;
713 }
714 #endif /* CONFIG_NFSD_V3 */
715 
716 int nfsd_open_break_lease(struct inode *inode, int access)
717 {
718 	unsigned int mode;
719 
720 	if (access & NFSD_MAY_NOT_BREAK_LEASE)
721 		return 0;
722 	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
723 	return break_lease(inode, mode | O_NONBLOCK);
724 }
725 
726 /*
727  * Open an existing file or directory.
728  * The may_flags argument indicates the type of open (read/write/lock)
729  * and additional flags.
730  * N.B. After this call fhp needs an fh_put
731  */
732 static __be32
733 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
734 			int may_flags, struct file **filp)
735 {
736 	struct path	path;
737 	struct inode	*inode;
738 	struct file	*file;
739 	int		flags = O_RDONLY|O_LARGEFILE;
740 	__be32		err;
741 	int		host_err = 0;
742 
743 	path.mnt = fhp->fh_export->ex_path.mnt;
744 	path.dentry = fhp->fh_dentry;
745 	inode = d_inode(path.dentry);
746 
747 	/* Disallow write access to files with the append-only bit set
748 	 * or any access when mandatory locking enabled
749 	 */
750 	err = nfserr_perm;
751 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
752 		goto out;
753 	/*
754 	 * We must ignore files (but only files) which might have mandatory
755 	 * locks on them because there is no way to know if the accesser has
756 	 * the lock.
757 	 */
758 	if (S_ISREG((inode)->i_mode) && mandatory_lock(inode))
759 		goto out;
760 
761 	if (!inode->i_fop)
762 		goto out;
763 
764 	host_err = nfsd_open_break_lease(inode, may_flags);
765 	if (host_err) /* NOMEM or WOULDBLOCK */
766 		goto out_nfserr;
767 
768 	if (may_flags & NFSD_MAY_WRITE) {
769 		if (may_flags & NFSD_MAY_READ)
770 			flags = O_RDWR|O_LARGEFILE;
771 		else
772 			flags = O_WRONLY|O_LARGEFILE;
773 	}
774 
775 	file = dentry_open(&path, flags, current_cred());
776 	if (IS_ERR(file)) {
777 		host_err = PTR_ERR(file);
778 		goto out_nfserr;
779 	}
780 
781 	host_err = ima_file_check(file, may_flags);
782 	if (host_err) {
783 		fput(file);
784 		goto out_nfserr;
785 	}
786 
787 	if (may_flags & NFSD_MAY_64BIT_COOKIE)
788 		file->f_mode |= FMODE_64BITHASH;
789 	else
790 		file->f_mode |= FMODE_32BITHASH;
791 
792 	*filp = file;
793 out_nfserr:
794 	err = nfserrno(host_err);
795 out:
796 	return err;
797 }
798 
799 __be32
800 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
801 		int may_flags, struct file **filp)
802 {
803 	__be32 err;
804 
805 	validate_process_creds();
806 	/*
807 	 * If we get here, then the client has already done an "open",
808 	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
809 	 * in case a chmod has now revoked permission.
810 	 *
811 	 * Arguably we should also allow the owner override for
812 	 * directories, but we never have and it doesn't seem to have
813 	 * caused anyone a problem.  If we were to change this, note
814 	 * also that our filldir callbacks would need a variant of
815 	 * lookup_one_len that doesn't check permissions.
816 	 */
817 	if (type == S_IFREG)
818 		may_flags |= NFSD_MAY_OWNER_OVERRIDE;
819 	err = fh_verify(rqstp, fhp, type, may_flags);
820 	if (!err)
821 		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
822 	validate_process_creds();
823 	return err;
824 }
825 
826 __be32
827 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
828 		int may_flags, struct file **filp)
829 {
830 	__be32 err;
831 
832 	validate_process_creds();
833 	err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
834 	validate_process_creds();
835 	return err;
836 }
837 
838 /*
839  * Grab and keep cached pages associated with a file in the svc_rqst
840  * so that they can be passed to the network sendmsg/sendpage routines
841  * directly. They will be released after the sending has completed.
842  */
843 static int
844 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
845 		  struct splice_desc *sd)
846 {
847 	struct svc_rqst *rqstp = sd->u.data;
848 	struct page **pp = rqstp->rq_next_page;
849 	struct page *page = buf->page;
850 	size_t size;
851 
852 	size = sd->len;
853 
854 	if (rqstp->rq_res.page_len == 0) {
855 		get_page(page);
856 		put_page(*rqstp->rq_next_page);
857 		*(rqstp->rq_next_page++) = page;
858 		rqstp->rq_res.page_base = buf->offset;
859 		rqstp->rq_res.page_len = size;
860 	} else if (page != pp[-1]) {
861 		get_page(page);
862 		if (*rqstp->rq_next_page)
863 			put_page(*rqstp->rq_next_page);
864 		*(rqstp->rq_next_page++) = page;
865 		rqstp->rq_res.page_len += size;
866 	} else
867 		rqstp->rq_res.page_len += size;
868 
869 	return size;
870 }
871 
872 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
873 				    struct splice_desc *sd)
874 {
875 	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
876 }
877 
878 static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
879 		size_t expected)
880 {
881 	if (expected != 0 && len == 0)
882 		return 1;
883 	if (offset+len >= i_size_read(file_inode(file)))
884 		return 1;
885 	return 0;
886 }
887 
888 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
889 			       struct file *file, loff_t offset,
890 			       unsigned long *count, u32 *eof, ssize_t host_err)
891 {
892 	if (host_err >= 0) {
893 		nfsd_stats_io_read_add(fhp->fh_export, host_err);
894 		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
895 		*count = host_err;
896 		fsnotify_access(file);
897 		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
898 		return 0;
899 	} else {
900 		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
901 		return nfserrno(host_err);
902 	}
903 }
904 
905 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
906 			struct file *file, loff_t offset, unsigned long *count,
907 			u32 *eof)
908 {
909 	struct splice_desc sd = {
910 		.len		= 0,
911 		.total_len	= *count,
912 		.pos		= offset,
913 		.u.data		= rqstp,
914 	};
915 	ssize_t host_err;
916 
917 	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
918 	rqstp->rq_next_page = rqstp->rq_respages + 1;
919 	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
920 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
921 }
922 
923 __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
924 		  struct file *file, loff_t offset,
925 		  struct kvec *vec, int vlen, unsigned long *count,
926 		  u32 *eof)
927 {
928 	struct iov_iter iter;
929 	loff_t ppos = offset;
930 	ssize_t host_err;
931 
932 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
933 	iov_iter_kvec(&iter, READ, vec, vlen, *count);
934 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
935 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
936 }
937 
938 /*
939  * Gathered writes: If another process is currently writing to the file,
940  * there's a high chance this is another nfsd (triggered by a bulk write
941  * from a client's biod). Rather than syncing the file with each write
942  * request, we sleep for 10 msec.
943  *
944  * I don't know if this roughly approximates C. Juszak's idea of
945  * gathered writes, but it's a nice and simple solution (IMHO), and it
946  * seems to work:-)
947  *
948  * Note: we do this only in the NFSv2 case, since v3 and higher have a
949  * better tool (separate unstable writes and commits) for solving this
950  * problem.
951  */
952 static int wait_for_concurrent_writes(struct file *file)
953 {
954 	struct inode *inode = file_inode(file);
955 	static ino_t last_ino;
956 	static dev_t last_dev;
957 	int err = 0;
958 
959 	if (atomic_read(&inode->i_writecount) > 1
960 	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
961 		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
962 		msleep(10);
963 		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
964 	}
965 
966 	if (inode->i_state & I_DIRTY) {
967 		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
968 		err = vfs_fsync(file, 0);
969 	}
970 	last_ino = inode->i_ino;
971 	last_dev = inode->i_sb->s_dev;
972 	return err;
973 }
974 
975 __be32
976 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
977 				loff_t offset, struct kvec *vec, int vlen,
978 				unsigned long *cnt, int stable,
979 				__be32 *verf)
980 {
981 	struct file		*file = nf->nf_file;
982 	struct super_block	*sb = file_inode(file)->i_sb;
983 	struct svc_export	*exp;
984 	struct iov_iter		iter;
985 	__be32			nfserr;
986 	int			host_err;
987 	int			use_wgather;
988 	loff_t			pos = offset;
989 	unsigned long		exp_op_flags = 0;
990 	unsigned int		pflags = current->flags;
991 	rwf_t			flags = 0;
992 	bool			restore_flags = false;
993 
994 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
995 
996 	if (sb->s_export_op)
997 		exp_op_flags = sb->s_export_op->flags;
998 
999 	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
1000 	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1001 		/*
1002 		 * We want throttling in balance_dirty_pages()
1003 		 * and shrink_inactive_list() to only consider
1004 		 * the backingdev we are writing to, so that nfs to
1005 		 * localhost doesn't cause nfsd to lock up due to all
1006 		 * the client's dirty pages or its congested queue.
1007 		 */
1008 		current->flags |= PF_LOCAL_THROTTLE;
1009 		restore_flags = true;
1010 	}
1011 
1012 	exp = fhp->fh_export;
1013 	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1014 
1015 	if (!EX_ISSYNC(exp))
1016 		stable = NFS_UNSTABLE;
1017 
1018 	if (stable && !use_wgather)
1019 		flags |= RWF_SYNC;
1020 
1021 	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
1022 	if (flags & RWF_SYNC) {
1023 		down_write(&nf->nf_rwsem);
1024 		host_err = vfs_iter_write(file, &iter, &pos, flags);
1025 		if (host_err < 0)
1026 			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1027 						 nfsd_net_id));
1028 		up_write(&nf->nf_rwsem);
1029 	} else {
1030 		down_read(&nf->nf_rwsem);
1031 		if (verf)
1032 			nfsd_copy_boot_verifier(verf,
1033 					net_generic(SVC_NET(rqstp),
1034 					nfsd_net_id));
1035 		host_err = vfs_iter_write(file, &iter, &pos, flags);
1036 		up_read(&nf->nf_rwsem);
1037 	}
1038 	if (host_err < 0) {
1039 		nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1040 					 nfsd_net_id));
1041 		goto out_nfserr;
1042 	}
1043 	*cnt = host_err;
1044 	nfsd_stats_io_write_add(exp, *cnt);
1045 	fsnotify_modify(file);
1046 
1047 	if (stable && use_wgather) {
1048 		host_err = wait_for_concurrent_writes(file);
1049 		if (host_err < 0)
1050 			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1051 						 nfsd_net_id));
1052 	}
1053 
1054 out_nfserr:
1055 	if (host_err >= 0) {
1056 		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1057 		nfserr = nfs_ok;
1058 	} else {
1059 		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1060 		nfserr = nfserrno(host_err);
1061 	}
1062 	if (restore_flags)
1063 		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1064 	return nfserr;
1065 }
1066 
1067 /*
1068  * Read data from a file. count must contain the requested read count
1069  * on entry. On return, *count contains the number of bytes actually read.
1070  * N.B. After this call fhp needs an fh_put
1071  */
1072 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1073 	loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
1074 	u32 *eof)
1075 {
1076 	struct nfsd_file	*nf;
1077 	struct file *file;
1078 	__be32 err;
1079 
1080 	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1081 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
1082 	if (err)
1083 		return err;
1084 
1085 	file = nf->nf_file;
1086 	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1087 		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1088 	else
1089 		err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
1090 
1091 	nfsd_file_put(nf);
1092 
1093 	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1094 
1095 	return err;
1096 }
1097 
1098 /*
1099  * Write data to a file.
1100  * The stable flag requests synchronous writes.
1101  * N.B. After this call fhp needs an fh_put
1102  */
1103 __be32
1104 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1105 	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1106 	   __be32 *verf)
1107 {
1108 	struct nfsd_file *nf;
1109 	__be32 err;
1110 
1111 	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1112 
1113 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1114 	if (err)
1115 		goto out;
1116 
1117 	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1118 			vlen, cnt, stable, verf);
1119 	nfsd_file_put(nf);
1120 out:
1121 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1122 	return err;
1123 }
1124 
1125 #ifdef CONFIG_NFSD_V3
1126 /*
1127  * Commit all pending writes to stable storage.
1128  *
1129  * Note: we only guarantee that data that lies within the range specified
1130  * by the 'offset' and 'count' parameters will be synced.
1131  *
1132  * Unfortunately we cannot lock the file to make sure we return full WCC
1133  * data to the client, as locking happens lower down in the filesystem.
1134  */
1135 __be32
1136 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
1137                loff_t offset, unsigned long count, __be32 *verf)
1138 {
1139 	struct nfsd_file	*nf;
1140 	loff_t			end = LLONG_MAX;
1141 	__be32			err = nfserr_inval;
1142 
1143 	if (offset < 0)
1144 		goto out;
1145 	if (count != 0) {
1146 		end = offset + (loff_t)count - 1;
1147 		if (end < offset)
1148 			goto out;
1149 	}
1150 
1151 	err = nfsd_file_acquire(rqstp, fhp,
1152 			NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
1153 	if (err)
1154 		goto out;
1155 	if (EX_ISSYNC(fhp->fh_export)) {
1156 		int err2;
1157 
1158 		down_write(&nf->nf_rwsem);
1159 		err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
1160 		switch (err2) {
1161 		case 0:
1162 			nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1163 						nfsd_net_id));
1164 			break;
1165 		case -EINVAL:
1166 			err = nfserr_notsupp;
1167 			break;
1168 		default:
1169 			err = nfserrno(err2);
1170 			nfsd_reset_boot_verifier(net_generic(nf->nf_net,
1171 						 nfsd_net_id));
1172 		}
1173 		up_write(&nf->nf_rwsem);
1174 	} else
1175 		nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1176 					nfsd_net_id));
1177 
1178 	nfsd_file_put(nf);
1179 out:
1180 	return err;
1181 }
1182 #endif /* CONFIG_NFSD_V3 */
1183 
1184 static __be32
1185 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *resfhp,
1186 			struct iattr *iap)
1187 {
1188 	/*
1189 	 * Mode has already been set earlier in create:
1190 	 */
1191 	iap->ia_valid &= ~ATTR_MODE;
1192 	/*
1193 	 * Setting uid/gid works only for root.  Irix appears to
1194 	 * send along the gid on create when it tries to implement
1195 	 * setgid directories via NFS:
1196 	 */
1197 	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1198 		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1199 	if (iap->ia_valid)
1200 		return nfsd_setattr(rqstp, resfhp, iap, 0, (time64_t)0);
1201 	/* Callers expect file metadata to be committed here */
1202 	return nfserrno(commit_metadata(resfhp));
1203 }
1204 
1205 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1206  * setting size to 0 may fail for some specific file systems by the permission
1207  * checking which requires WRITE permission but the mode is 000.
1208  * we ignore the resizing(to 0) on the just new created file, since the size is
1209  * 0 after file created.
1210  *
1211  * call this only after vfs_create() is called.
1212  * */
1213 static void
1214 nfsd_check_ignore_resizing(struct iattr *iap)
1215 {
1216 	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1217 		iap->ia_valid &= ~ATTR_SIZE;
1218 }
1219 
1220 /* The parent directory should already be locked: */
1221 __be32
1222 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1223 		char *fname, int flen, struct iattr *iap,
1224 		int type, dev_t rdev, struct svc_fh *resfhp)
1225 {
1226 	struct dentry	*dentry, *dchild;
1227 	struct inode	*dirp;
1228 	__be32		err;
1229 	__be32		err2;
1230 	int		host_err;
1231 
1232 	dentry = fhp->fh_dentry;
1233 	dirp = d_inode(dentry);
1234 
1235 	dchild = dget(resfhp->fh_dentry);
1236 	if (!fhp->fh_locked) {
1237 		WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
1238 				dentry);
1239 		err = nfserr_io;
1240 		goto out;
1241 	}
1242 
1243 	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1244 	if (err)
1245 		goto out;
1246 
1247 	if (!(iap->ia_valid & ATTR_MODE))
1248 		iap->ia_mode = 0;
1249 	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1250 
1251 	if (!IS_POSIXACL(dirp))
1252 		iap->ia_mode &= ~current_umask();
1253 
1254 	err = 0;
1255 	host_err = 0;
1256 	switch (type) {
1257 	case S_IFREG:
1258 		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1259 		if (!host_err)
1260 			nfsd_check_ignore_resizing(iap);
1261 		break;
1262 	case S_IFDIR:
1263 		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
1264 		if (!host_err && unlikely(d_unhashed(dchild))) {
1265 			struct dentry *d;
1266 			d = lookup_one_len(dchild->d_name.name,
1267 					   dchild->d_parent,
1268 					   dchild->d_name.len);
1269 			if (IS_ERR(d)) {
1270 				host_err = PTR_ERR(d);
1271 				break;
1272 			}
1273 			if (unlikely(d_is_negative(d))) {
1274 				dput(d);
1275 				err = nfserr_serverfault;
1276 				goto out;
1277 			}
1278 			dput(resfhp->fh_dentry);
1279 			resfhp->fh_dentry = dget(d);
1280 			err = fh_update(resfhp);
1281 			dput(dchild);
1282 			dchild = d;
1283 			if (err)
1284 				goto out;
1285 		}
1286 		break;
1287 	case S_IFCHR:
1288 	case S_IFBLK:
1289 	case S_IFIFO:
1290 	case S_IFSOCK:
1291 		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
1292 				     iap->ia_mode, rdev);
1293 		break;
1294 	default:
1295 		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1296 		       type);
1297 		host_err = -EINVAL;
1298 	}
1299 	if (host_err < 0)
1300 		goto out_nfserr;
1301 
1302 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1303 
1304 	/*
1305 	 * nfsd_create_setattr already committed the child.  Transactional
1306 	 * filesystems had a chance to commit changes for both parent and
1307 	 * child simultaneously making the following commit_metadata a
1308 	 * noop.
1309 	 */
1310 	err2 = nfserrno(commit_metadata(fhp));
1311 	if (err2)
1312 		err = err2;
1313 	/*
1314 	 * Update the file handle to get the new inode info.
1315 	 */
1316 	if (!err)
1317 		err = fh_update(resfhp);
1318 out:
1319 	dput(dchild);
1320 	return err;
1321 
1322 out_nfserr:
1323 	err = nfserrno(host_err);
1324 	goto out;
1325 }
1326 
1327 /*
1328  * Create a filesystem object (regular, directory, special).
1329  * Note that the parent directory is left locked.
1330  *
1331  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1332  */
1333 __be32
1334 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1335 		char *fname, int flen, struct iattr *iap,
1336 		int type, dev_t rdev, struct svc_fh *resfhp)
1337 {
1338 	struct dentry	*dentry, *dchild = NULL;
1339 	__be32		err;
1340 	int		host_err;
1341 
1342 	if (isdotent(fname, flen))
1343 		return nfserr_exist;
1344 
1345 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1346 	if (err)
1347 		return err;
1348 
1349 	dentry = fhp->fh_dentry;
1350 
1351 	host_err = fh_want_write(fhp);
1352 	if (host_err)
1353 		return nfserrno(host_err);
1354 
1355 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1356 	dchild = lookup_one_len(fname, dentry, flen);
1357 	host_err = PTR_ERR(dchild);
1358 	if (IS_ERR(dchild))
1359 		return nfserrno(host_err);
1360 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1361 	/*
1362 	 * We unconditionally drop our ref to dchild as fh_compose will have
1363 	 * already grabbed its own ref for it.
1364 	 */
1365 	dput(dchild);
1366 	if (err)
1367 		return err;
1368 	return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
1369 					rdev, resfhp);
1370 }
1371 
1372 #ifdef CONFIG_NFSD_V3
1373 
1374 /*
1375  * NFSv3 and NFSv4 version of nfsd_create
1376  */
1377 __be32
1378 do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1379 		char *fname, int flen, struct iattr *iap,
1380 		struct svc_fh *resfhp, int createmode, u32 *verifier,
1381 	        bool *truncp, bool *created)
1382 {
1383 	struct dentry	*dentry, *dchild = NULL;
1384 	struct inode	*dirp;
1385 	__be32		err;
1386 	int		host_err;
1387 	__u32		v_mtime=0, v_atime=0;
1388 
1389 	err = nfserr_perm;
1390 	if (!flen)
1391 		goto out;
1392 	err = nfserr_exist;
1393 	if (isdotent(fname, flen))
1394 		goto out;
1395 	if (!(iap->ia_valid & ATTR_MODE))
1396 		iap->ia_mode = 0;
1397 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
1398 	if (err)
1399 		goto out;
1400 
1401 	dentry = fhp->fh_dentry;
1402 	dirp = d_inode(dentry);
1403 
1404 	host_err = fh_want_write(fhp);
1405 	if (host_err)
1406 		goto out_nfserr;
1407 
1408 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1409 
1410 	/*
1411 	 * Compose the response file handle.
1412 	 */
1413 	dchild = lookup_one_len(fname, dentry, flen);
1414 	host_err = PTR_ERR(dchild);
1415 	if (IS_ERR(dchild))
1416 		goto out_nfserr;
1417 
1418 	/* If file doesn't exist, check for permissions to create one */
1419 	if (d_really_is_negative(dchild)) {
1420 		err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1421 		if (err)
1422 			goto out;
1423 	}
1424 
1425 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1426 	if (err)
1427 		goto out;
1428 
1429 	if (nfsd_create_is_exclusive(createmode)) {
1430 		/* solaris7 gets confused (bugid 4218508) if these have
1431 		 * the high bit set, so just clear the high bits. If this is
1432 		 * ever changed to use different attrs for storing the
1433 		 * verifier, then do_open_lookup() will also need to be fixed
1434 		 * accordingly.
1435 		 */
1436 		v_mtime = verifier[0]&0x7fffffff;
1437 		v_atime = verifier[1]&0x7fffffff;
1438 	}
1439 
1440 	if (d_really_is_positive(dchild)) {
1441 		err = 0;
1442 
1443 		switch (createmode) {
1444 		case NFS3_CREATE_UNCHECKED:
1445 			if (! d_is_reg(dchild))
1446 				goto out;
1447 			else if (truncp) {
1448 				/* in nfsv4, we need to treat this case a little
1449 				 * differently.  we don't want to truncate the
1450 				 * file now; this would be wrong if the OPEN
1451 				 * fails for some other reason.  furthermore,
1452 				 * if the size is nonzero, we should ignore it
1453 				 * according to spec!
1454 				 */
1455 				*truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
1456 			}
1457 			else {
1458 				iap->ia_valid &= ATTR_SIZE;
1459 				goto set_attr;
1460 			}
1461 			break;
1462 		case NFS3_CREATE_EXCLUSIVE:
1463 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1464 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1465 			    && d_inode(dchild)->i_size  == 0 ) {
1466 				if (created)
1467 					*created = true;
1468 				break;
1469 			}
1470 			fallthrough;
1471 		case NFS4_CREATE_EXCLUSIVE4_1:
1472 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1473 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1474 			    && d_inode(dchild)->i_size  == 0 ) {
1475 				if (created)
1476 					*created = true;
1477 				goto set_attr;
1478 			}
1479 			fallthrough;
1480 		case NFS3_CREATE_GUARDED:
1481 			err = nfserr_exist;
1482 		}
1483 		fh_drop_write(fhp);
1484 		goto out;
1485 	}
1486 
1487 	if (!IS_POSIXACL(dirp))
1488 		iap->ia_mode &= ~current_umask();
1489 
1490 	host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1491 	if (host_err < 0) {
1492 		fh_drop_write(fhp);
1493 		goto out_nfserr;
1494 	}
1495 	if (created)
1496 		*created = true;
1497 
1498 	nfsd_check_ignore_resizing(iap);
1499 
1500 	if (nfsd_create_is_exclusive(createmode)) {
1501 		/* Cram the verifier into atime/mtime */
1502 		iap->ia_valid = ATTR_MTIME|ATTR_ATIME
1503 			| ATTR_MTIME_SET|ATTR_ATIME_SET;
1504 		/* XXX someone who knows this better please fix it for nsec */
1505 		iap->ia_mtime.tv_sec = v_mtime;
1506 		iap->ia_atime.tv_sec = v_atime;
1507 		iap->ia_mtime.tv_nsec = 0;
1508 		iap->ia_atime.tv_nsec = 0;
1509 	}
1510 
1511  set_attr:
1512 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1513 
1514 	/*
1515 	 * nfsd_create_setattr already committed the child
1516 	 * (and possibly also the parent).
1517 	 */
1518 	if (!err)
1519 		err = nfserrno(commit_metadata(fhp));
1520 
1521 	/*
1522 	 * Update the filehandle to get the new inode info.
1523 	 */
1524 	if (!err)
1525 		err = fh_update(resfhp);
1526 
1527  out:
1528 	fh_unlock(fhp);
1529 	if (dchild && !IS_ERR(dchild))
1530 		dput(dchild);
1531 	fh_drop_write(fhp);
1532  	return err;
1533 
1534  out_nfserr:
1535 	err = nfserrno(host_err);
1536 	goto out;
1537 }
1538 #endif /* CONFIG_NFSD_V3 */
1539 
1540 /*
1541  * Read a symlink. On entry, *lenp must contain the maximum path length that
1542  * fits into the buffer. On return, it contains the true length.
1543  * N.B. After this call fhp needs an fh_put
1544  */
1545 __be32
1546 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1547 {
1548 	__be32		err;
1549 	const char *link;
1550 	struct path path;
1551 	DEFINE_DELAYED_CALL(done);
1552 	int len;
1553 
1554 	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1555 	if (unlikely(err))
1556 		return err;
1557 
1558 	path.mnt = fhp->fh_export->ex_path.mnt;
1559 	path.dentry = fhp->fh_dentry;
1560 
1561 	if (unlikely(!d_is_symlink(path.dentry)))
1562 		return nfserr_inval;
1563 
1564 	touch_atime(&path);
1565 
1566 	link = vfs_get_link(path.dentry, &done);
1567 	if (IS_ERR(link))
1568 		return nfserrno(PTR_ERR(link));
1569 
1570 	len = strlen(link);
1571 	if (len < *lenp)
1572 		*lenp = len;
1573 	memcpy(buf, link, *lenp);
1574 	do_delayed_call(&done);
1575 	return 0;
1576 }
1577 
1578 /*
1579  * Create a symlink and look up its inode
1580  * N.B. After this call _both_ fhp and resfhp need an fh_put
1581  */
1582 __be32
1583 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1584 				char *fname, int flen,
1585 				char *path,
1586 				struct svc_fh *resfhp)
1587 {
1588 	struct dentry	*dentry, *dnew;
1589 	__be32		err, cerr;
1590 	int		host_err;
1591 
1592 	err = nfserr_noent;
1593 	if (!flen || path[0] == '\0')
1594 		goto out;
1595 	err = nfserr_exist;
1596 	if (isdotent(fname, flen))
1597 		goto out;
1598 
1599 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1600 	if (err)
1601 		goto out;
1602 
1603 	host_err = fh_want_write(fhp);
1604 	if (host_err)
1605 		goto out_nfserr;
1606 
1607 	fh_lock(fhp);
1608 	dentry = fhp->fh_dentry;
1609 	dnew = lookup_one_len(fname, dentry, flen);
1610 	host_err = PTR_ERR(dnew);
1611 	if (IS_ERR(dnew))
1612 		goto out_nfserr;
1613 
1614 	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
1615 	err = nfserrno(host_err);
1616 	if (!err)
1617 		err = nfserrno(commit_metadata(fhp));
1618 	fh_unlock(fhp);
1619 
1620 	fh_drop_write(fhp);
1621 
1622 	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1623 	dput(dnew);
1624 	if (err==0) err = cerr;
1625 out:
1626 	return err;
1627 
1628 out_nfserr:
1629 	err = nfserrno(host_err);
1630 	goto out;
1631 }
1632 
1633 /*
1634  * Create a hardlink
1635  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1636  */
1637 __be32
1638 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1639 				char *name, int len, struct svc_fh *tfhp)
1640 {
1641 	struct dentry	*ddir, *dnew, *dold;
1642 	struct inode	*dirp;
1643 	__be32		err;
1644 	int		host_err;
1645 
1646 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1647 	if (err)
1648 		goto out;
1649 	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1650 	if (err)
1651 		goto out;
1652 	err = nfserr_isdir;
1653 	if (d_is_dir(tfhp->fh_dentry))
1654 		goto out;
1655 	err = nfserr_perm;
1656 	if (!len)
1657 		goto out;
1658 	err = nfserr_exist;
1659 	if (isdotent(name, len))
1660 		goto out;
1661 
1662 	host_err = fh_want_write(tfhp);
1663 	if (host_err) {
1664 		err = nfserrno(host_err);
1665 		goto out;
1666 	}
1667 
1668 	fh_lock_nested(ffhp, I_MUTEX_PARENT);
1669 	ddir = ffhp->fh_dentry;
1670 	dirp = d_inode(ddir);
1671 
1672 	dnew = lookup_one_len(name, ddir, len);
1673 	host_err = PTR_ERR(dnew);
1674 	if (IS_ERR(dnew))
1675 		goto out_nfserr;
1676 
1677 	dold = tfhp->fh_dentry;
1678 
1679 	err = nfserr_noent;
1680 	if (d_really_is_negative(dold))
1681 		goto out_dput;
1682 	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
1683 	if (!host_err) {
1684 		err = nfserrno(commit_metadata(ffhp));
1685 		if (!err)
1686 			err = nfserrno(commit_metadata(tfhp));
1687 	} else {
1688 		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1689 			err = nfserr_acces;
1690 		else
1691 			err = nfserrno(host_err);
1692 	}
1693 out_dput:
1694 	dput(dnew);
1695 out_unlock:
1696 	fh_unlock(ffhp);
1697 	fh_drop_write(tfhp);
1698 out:
1699 	return err;
1700 
1701 out_nfserr:
1702 	err = nfserrno(host_err);
1703 	goto out_unlock;
1704 }
1705 
1706 static void
1707 nfsd_close_cached_files(struct dentry *dentry)
1708 {
1709 	struct inode *inode = d_inode(dentry);
1710 
1711 	if (inode && S_ISREG(inode->i_mode))
1712 		nfsd_file_close_inode_sync(inode);
1713 }
1714 
1715 static bool
1716 nfsd_has_cached_files(struct dentry *dentry)
1717 {
1718 	bool		ret = false;
1719 	struct inode *inode = d_inode(dentry);
1720 
1721 	if (inode && S_ISREG(inode->i_mode))
1722 		ret = nfsd_file_is_cached(inode);
1723 	return ret;
1724 }
1725 
1726 /*
1727  * Rename a file
1728  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1729  */
1730 __be32
1731 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1732 			    struct svc_fh *tfhp, char *tname, int tlen)
1733 {
1734 	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1735 	struct inode	*fdir, *tdir;
1736 	__be32		err;
1737 	int		host_err;
1738 	bool		close_cached = false;
1739 
1740 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1741 	if (err)
1742 		goto out;
1743 	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1744 	if (err)
1745 		goto out;
1746 
1747 	fdentry = ffhp->fh_dentry;
1748 	fdir = d_inode(fdentry);
1749 
1750 	tdentry = tfhp->fh_dentry;
1751 	tdir = d_inode(tdentry);
1752 
1753 	err = nfserr_perm;
1754 	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1755 		goto out;
1756 
1757 retry:
1758 	host_err = fh_want_write(ffhp);
1759 	if (host_err) {
1760 		err = nfserrno(host_err);
1761 		goto out;
1762 	}
1763 
1764 	/* cannot use fh_lock as we need deadlock protective ordering
1765 	 * so do it by hand */
1766 	trap = lock_rename(tdentry, fdentry);
1767 	ffhp->fh_locked = tfhp->fh_locked = true;
1768 	fill_pre_wcc(ffhp);
1769 	fill_pre_wcc(tfhp);
1770 
1771 	odentry = lookup_one_len(fname, fdentry, flen);
1772 	host_err = PTR_ERR(odentry);
1773 	if (IS_ERR(odentry))
1774 		goto out_nfserr;
1775 
1776 	host_err = -ENOENT;
1777 	if (d_really_is_negative(odentry))
1778 		goto out_dput_old;
1779 	host_err = -EINVAL;
1780 	if (odentry == trap)
1781 		goto out_dput_old;
1782 
1783 	ndentry = lookup_one_len(tname, tdentry, tlen);
1784 	host_err = PTR_ERR(ndentry);
1785 	if (IS_ERR(ndentry))
1786 		goto out_dput_old;
1787 	host_err = -ENOTEMPTY;
1788 	if (ndentry == trap)
1789 		goto out_dput_new;
1790 
1791 	host_err = -EXDEV;
1792 	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1793 		goto out_dput_new;
1794 	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1795 		goto out_dput_new;
1796 
1797 	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1798 	    nfsd_has_cached_files(ndentry)) {
1799 		close_cached = true;
1800 		goto out_dput_old;
1801 	} else {
1802 		struct renamedata rd = {
1803 			.old_mnt_userns	= &init_user_ns,
1804 			.old_dir	= fdir,
1805 			.old_dentry	= odentry,
1806 			.new_mnt_userns	= &init_user_ns,
1807 			.new_dir	= tdir,
1808 			.new_dentry	= ndentry,
1809 		};
1810 		host_err = vfs_rename(&rd);
1811 		if (!host_err) {
1812 			host_err = commit_metadata(tfhp);
1813 			if (!host_err)
1814 				host_err = commit_metadata(ffhp);
1815 		}
1816 	}
1817  out_dput_new:
1818 	dput(ndentry);
1819  out_dput_old:
1820 	dput(odentry);
1821  out_nfserr:
1822 	err = nfserrno(host_err);
1823 	/*
1824 	 * We cannot rely on fh_unlock on the two filehandles,
1825 	 * as that would do the wrong thing if the two directories
1826 	 * were the same, so again we do it by hand.
1827 	 */
1828 	if (!close_cached) {
1829 		fill_post_wcc(ffhp);
1830 		fill_post_wcc(tfhp);
1831 	}
1832 	unlock_rename(tdentry, fdentry);
1833 	ffhp->fh_locked = tfhp->fh_locked = false;
1834 	fh_drop_write(ffhp);
1835 
1836 	/*
1837 	 * If the target dentry has cached open files, then we need to try to
1838 	 * close them prior to doing the rename. Flushing delayed fput
1839 	 * shouldn't be done with locks held however, so we delay it until this
1840 	 * point and then reattempt the whole shebang.
1841 	 */
1842 	if (close_cached) {
1843 		close_cached = false;
1844 		nfsd_close_cached_files(ndentry);
1845 		dput(ndentry);
1846 		goto retry;
1847 	}
1848 out:
1849 	return err;
1850 }
1851 
1852 /*
1853  * Unlink a file or directory
1854  * N.B. After this call fhp needs an fh_put
1855  */
1856 __be32
1857 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1858 				char *fname, int flen)
1859 {
1860 	struct dentry	*dentry, *rdentry;
1861 	struct inode	*dirp;
1862 	__be32		err;
1863 	int		host_err;
1864 
1865 	err = nfserr_acces;
1866 	if (!flen || isdotent(fname, flen))
1867 		goto out;
1868 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1869 	if (err)
1870 		goto out;
1871 
1872 	host_err = fh_want_write(fhp);
1873 	if (host_err)
1874 		goto out_nfserr;
1875 
1876 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1877 	dentry = fhp->fh_dentry;
1878 	dirp = d_inode(dentry);
1879 
1880 	rdentry = lookup_one_len(fname, dentry, flen);
1881 	host_err = PTR_ERR(rdentry);
1882 	if (IS_ERR(rdentry))
1883 		goto out_drop_write;
1884 
1885 	if (d_really_is_negative(rdentry)) {
1886 		dput(rdentry);
1887 		host_err = -ENOENT;
1888 		goto out_drop_write;
1889 	}
1890 
1891 	if (!type)
1892 		type = d_inode(rdentry)->i_mode & S_IFMT;
1893 
1894 	if (type != S_IFDIR) {
1895 		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1896 			nfsd_close_cached_files(rdentry);
1897 		host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
1898 	} else {
1899 		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
1900 	}
1901 
1902 	if (!host_err)
1903 		host_err = commit_metadata(fhp);
1904 	dput(rdentry);
1905 
1906 out_drop_write:
1907 	fh_drop_write(fhp);
1908 out_nfserr:
1909 	if (host_err == -EBUSY) {
1910 		/* name is mounted-on. There is no perfect
1911 		 * error status.
1912 		 */
1913 		if (nfsd_v4client(rqstp))
1914 			err = nfserr_file_open;
1915 		else
1916 			err = nfserr_acces;
1917 	} else {
1918 		err = nfserrno(host_err);
1919 	}
1920 out:
1921 	return err;
1922 }
1923 
1924 /*
1925  * We do this buffering because we must not call back into the file
1926  * system's ->lookup() method from the filldir callback. That may well
1927  * deadlock a number of file systems.
1928  *
1929  * This is based heavily on the implementation of same in XFS.
1930  */
1931 struct buffered_dirent {
1932 	u64		ino;
1933 	loff_t		offset;
1934 	int		namlen;
1935 	unsigned int	d_type;
1936 	char		name[];
1937 };
1938 
1939 struct readdir_data {
1940 	struct dir_context ctx;
1941 	char		*dirent;
1942 	size_t		used;
1943 	int		full;
1944 };
1945 
1946 static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1947 				 int namlen, loff_t offset, u64 ino,
1948 				 unsigned int d_type)
1949 {
1950 	struct readdir_data *buf =
1951 		container_of(ctx, struct readdir_data, ctx);
1952 	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1953 	unsigned int reclen;
1954 
1955 	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1956 	if (buf->used + reclen > PAGE_SIZE) {
1957 		buf->full = 1;
1958 		return -EINVAL;
1959 	}
1960 
1961 	de->namlen = namlen;
1962 	de->offset = offset;
1963 	de->ino = ino;
1964 	de->d_type = d_type;
1965 	memcpy(de->name, name, namlen);
1966 	buf->used += reclen;
1967 
1968 	return 0;
1969 }
1970 
1971 static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
1972 				    nfsd_filldir_t func, struct readdir_cd *cdp,
1973 				    loff_t *offsetp)
1974 {
1975 	struct buffered_dirent *de;
1976 	int host_err;
1977 	int size;
1978 	loff_t offset;
1979 	struct readdir_data buf = {
1980 		.ctx.actor = nfsd_buffered_filldir,
1981 		.dirent = (void *)__get_free_page(GFP_KERNEL)
1982 	};
1983 
1984 	if (!buf.dirent)
1985 		return nfserrno(-ENOMEM);
1986 
1987 	offset = *offsetp;
1988 
1989 	while (1) {
1990 		unsigned int reclen;
1991 
1992 		cdp->err = nfserr_eof; /* will be cleared on successful read */
1993 		buf.used = 0;
1994 		buf.full = 0;
1995 
1996 		host_err = iterate_dir(file, &buf.ctx);
1997 		if (buf.full)
1998 			host_err = 0;
1999 
2000 		if (host_err < 0)
2001 			break;
2002 
2003 		size = buf.used;
2004 
2005 		if (!size)
2006 			break;
2007 
2008 		de = (struct buffered_dirent *)buf.dirent;
2009 		while (size > 0) {
2010 			offset = de->offset;
2011 
2012 			if (func(cdp, de->name, de->namlen, de->offset,
2013 				 de->ino, de->d_type))
2014 				break;
2015 
2016 			if (cdp->err != nfs_ok)
2017 				break;
2018 
2019 			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
2020 
2021 			reclen = ALIGN(sizeof(*de) + de->namlen,
2022 				       sizeof(u64));
2023 			size -= reclen;
2024 			de = (struct buffered_dirent *)((char *)de + reclen);
2025 		}
2026 		if (size > 0) /* We bailed out early */
2027 			break;
2028 
2029 		offset = vfs_llseek(file, 0, SEEK_CUR);
2030 	}
2031 
2032 	free_page((unsigned long)(buf.dirent));
2033 
2034 	if (host_err)
2035 		return nfserrno(host_err);
2036 
2037 	*offsetp = offset;
2038 	return cdp->err;
2039 }
2040 
2041 /*
2042  * Read entries from a directory.
2043  * The  NFSv3/4 verifier we ignore for now.
2044  */
2045 __be32
2046 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2047 	     struct readdir_cd *cdp, nfsd_filldir_t func)
2048 {
2049 	__be32		err;
2050 	struct file	*file;
2051 	loff_t		offset = *offsetp;
2052 	int             may_flags = NFSD_MAY_READ;
2053 
2054 	/* NFSv2 only supports 32 bit cookies */
2055 	if (rqstp->rq_vers > 2)
2056 		may_flags |= NFSD_MAY_64BIT_COOKIE;
2057 
2058 	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2059 	if (err)
2060 		goto out;
2061 
2062 	offset = vfs_llseek(file, offset, SEEK_SET);
2063 	if (offset < 0) {
2064 		err = nfserrno((int)offset);
2065 		goto out_close;
2066 	}
2067 
2068 	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2069 
2070 	if (err == nfserr_eof || err == nfserr_toosmall)
2071 		err = nfs_ok; /* can still be found in ->err */
2072 out_close:
2073 	fput(file);
2074 out:
2075 	return err;
2076 }
2077 
2078 /*
2079  * Get file system stats
2080  * N.B. After this call fhp needs an fh_put
2081  */
2082 __be32
2083 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2084 {
2085 	__be32 err;
2086 
2087 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2088 	if (!err) {
2089 		struct path path = {
2090 			.mnt	= fhp->fh_export->ex_path.mnt,
2091 			.dentry	= fhp->fh_dentry,
2092 		};
2093 		if (vfs_statfs(&path, stat))
2094 			err = nfserr_io;
2095 	}
2096 	return err;
2097 }
2098 
2099 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2100 {
2101 	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2102 }
2103 
2104 #ifdef CONFIG_NFSD_V4
2105 /*
2106  * Helper function to translate error numbers. In the case of xattr operations,
2107  * some error codes need to be translated outside of the standard translations.
2108  *
2109  * ENODATA needs to be translated to nfserr_noxattr.
2110  * E2BIG to nfserr_xattr2big.
2111  *
2112  * Additionally, vfs_listxattr can return -ERANGE. This means that the
2113  * file has too many extended attributes to retrieve inside an
2114  * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2115  * filesystems will allow the adding of extended attributes until they hit
2116  * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2117  * So, at that point, the attributes are present and valid, but can't
2118  * be retrieved using listxattr, since the upper level xattr code enforces
2119  * the XATTR_LIST_MAX limit.
2120  *
2121  * This bug means that we need to deal with listxattr returning -ERANGE. The
2122  * best mapping is to return TOOSMALL.
2123  */
2124 static __be32
2125 nfsd_xattr_errno(int err)
2126 {
2127 	switch (err) {
2128 	case -ENODATA:
2129 		return nfserr_noxattr;
2130 	case -E2BIG:
2131 		return nfserr_xattr2big;
2132 	case -ERANGE:
2133 		return nfserr_toosmall;
2134 	}
2135 	return nfserrno(err);
2136 }
2137 
2138 /*
2139  * Retrieve the specified user extended attribute. To avoid always
2140  * having to allocate the maximum size (since we are not getting
2141  * a maximum size from the RPC), do a probe + alloc. Hold a reader
2142  * lock on i_rwsem to prevent the extended attribute from changing
2143  * size while we're doing this.
2144  */
2145 __be32
2146 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2147 	      void **bufp, int *lenp)
2148 {
2149 	ssize_t len;
2150 	__be32 err;
2151 	char *buf;
2152 	struct inode *inode;
2153 	struct dentry *dentry;
2154 
2155 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2156 	if (err)
2157 		return err;
2158 
2159 	err = nfs_ok;
2160 	dentry = fhp->fh_dentry;
2161 	inode = d_inode(dentry);
2162 
2163 	inode_lock_shared(inode);
2164 
2165 	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
2166 
2167 	/*
2168 	 * Zero-length attribute, just return.
2169 	 */
2170 	if (len == 0) {
2171 		*bufp = NULL;
2172 		*lenp = 0;
2173 		goto out;
2174 	}
2175 
2176 	if (len < 0) {
2177 		err = nfsd_xattr_errno(len);
2178 		goto out;
2179 	}
2180 
2181 	if (len > *lenp) {
2182 		err = nfserr_toosmall;
2183 		goto out;
2184 	}
2185 
2186 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2187 	if (buf == NULL) {
2188 		err = nfserr_jukebox;
2189 		goto out;
2190 	}
2191 
2192 	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
2193 	if (len <= 0) {
2194 		kvfree(buf);
2195 		buf = NULL;
2196 		err = nfsd_xattr_errno(len);
2197 	}
2198 
2199 	*lenp = len;
2200 	*bufp = buf;
2201 
2202 out:
2203 	inode_unlock_shared(inode);
2204 
2205 	return err;
2206 }
2207 
2208 /*
2209  * Retrieve the xattr names. Since we can't know how many are
2210  * user extended attributes, we must get all attributes here,
2211  * and have the XDR encode filter out the "user." ones.
2212  *
2213  * While this could always just allocate an XATTR_LIST_MAX
2214  * buffer, that's a waste, so do a probe + allocate. To
2215  * avoid any changes between the probe and allocate, wrap
2216  * this in inode_lock.
2217  */
2218 __be32
2219 nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2220 	       int *lenp)
2221 {
2222 	ssize_t len;
2223 	__be32 err;
2224 	char *buf;
2225 	struct inode *inode;
2226 	struct dentry *dentry;
2227 
2228 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2229 	if (err)
2230 		return err;
2231 
2232 	dentry = fhp->fh_dentry;
2233 	inode = d_inode(dentry);
2234 	*lenp = 0;
2235 
2236 	inode_lock_shared(inode);
2237 
2238 	len = vfs_listxattr(dentry, NULL, 0);
2239 	if (len <= 0) {
2240 		err = nfsd_xattr_errno(len);
2241 		goto out;
2242 	}
2243 
2244 	if (len > XATTR_LIST_MAX) {
2245 		err = nfserr_xattr2big;
2246 		goto out;
2247 	}
2248 
2249 	/*
2250 	 * We're holding i_rwsem - use GFP_NOFS.
2251 	 */
2252 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2253 	if (buf == NULL) {
2254 		err = nfserr_jukebox;
2255 		goto out;
2256 	}
2257 
2258 	len = vfs_listxattr(dentry, buf, len);
2259 	if (len <= 0) {
2260 		kvfree(buf);
2261 		err = nfsd_xattr_errno(len);
2262 		goto out;
2263 	}
2264 
2265 	*lenp = len;
2266 	*bufp = buf;
2267 
2268 	err = nfs_ok;
2269 out:
2270 	inode_unlock_shared(inode);
2271 
2272 	return err;
2273 }
2274 
2275 /*
2276  * Removexattr and setxattr need to call fh_lock to both lock the inode
2277  * and set the change attribute. Since the top-level vfs_removexattr
2278  * and vfs_setxattr calls already do their own inode_lock calls, call
2279  * the _locked variant. Pass in a NULL pointer for delegated_inode,
2280  * and let the client deal with NFS4ERR_DELAY (same as with e.g.
2281  * setattr and remove).
2282  */
2283 __be32
2284 nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2285 {
2286 	__be32 err;
2287 	int ret;
2288 
2289 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2290 	if (err)
2291 		return err;
2292 
2293 	ret = fh_want_write(fhp);
2294 	if (ret)
2295 		return nfserrno(ret);
2296 
2297 	fh_lock(fhp);
2298 
2299 	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
2300 				       name, NULL);
2301 
2302 	fh_unlock(fhp);
2303 	fh_drop_write(fhp);
2304 
2305 	return nfsd_xattr_errno(ret);
2306 }
2307 
2308 __be32
2309 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2310 	      void *buf, u32 len, u32 flags)
2311 {
2312 	__be32 err;
2313 	int ret;
2314 
2315 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2316 	if (err)
2317 		return err;
2318 
2319 	ret = fh_want_write(fhp);
2320 	if (ret)
2321 		return nfserrno(ret);
2322 	fh_lock(fhp);
2323 
2324 	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
2325 				    len, flags, NULL);
2326 
2327 	fh_unlock(fhp);
2328 	fh_drop_write(fhp);
2329 
2330 	return nfsd_xattr_errno(ret);
2331 }
2332 #endif
2333 
2334 /*
2335  * Check for a user's access permissions to this inode.
2336  */
2337 __be32
2338 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2339 					struct dentry *dentry, int acc)
2340 {
2341 	struct inode	*inode = d_inode(dentry);
2342 	int		err;
2343 
2344 	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2345 		return 0;
2346 #if 0
2347 	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2348 		acc,
2349 		(acc & NFSD_MAY_READ)?	" read"  : "",
2350 		(acc & NFSD_MAY_WRITE)?	" write" : "",
2351 		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2352 		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2353 		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2354 		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2355 		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2356 		inode->i_mode,
2357 		IS_IMMUTABLE(inode)?	" immut" : "",
2358 		IS_APPEND(inode)?	" append" : "",
2359 		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2360 	dprintk("      owner %d/%d user %d/%d\n",
2361 		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2362 #endif
2363 
2364 	/* Normally we reject any write/sattr etc access on a read-only file
2365 	 * system.  But if it is IRIX doing check on write-access for a
2366 	 * device special file, we ignore rofs.
2367 	 */
2368 	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2369 		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2370 			if (exp_rdonly(rqstp, exp) ||
2371 			    __mnt_is_readonly(exp->ex_path.mnt))
2372 				return nfserr_rofs;
2373 			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2374 				return nfserr_perm;
2375 		}
2376 	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2377 		return nfserr_perm;
2378 
2379 	if (acc & NFSD_MAY_LOCK) {
2380 		/* If we cannot rely on authentication in NLM requests,
2381 		 * just allow locks, otherwise require read permission, or
2382 		 * ownership
2383 		 */
2384 		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2385 			return 0;
2386 		else
2387 			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2388 	}
2389 	/*
2390 	 * The file owner always gets access permission for accesses that
2391 	 * would normally be checked at open time. This is to make
2392 	 * file access work even when the client has done a fchmod(fd, 0).
2393 	 *
2394 	 * However, `cp foo bar' should fail nevertheless when bar is
2395 	 * readonly. A sensible way to do this might be to reject all
2396 	 * attempts to truncate a read-only file, because a creat() call
2397 	 * always implies file truncation.
2398 	 * ... but this isn't really fair.  A process may reasonably call
2399 	 * ftruncate on an open file descriptor on a file with perm 000.
2400 	 * We must trust the client to do permission checking - using "ACCESS"
2401 	 * with NFSv3.
2402 	 */
2403 	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2404 	    uid_eq(inode->i_uid, current_fsuid()))
2405 		return 0;
2406 
2407 	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2408 	err = inode_permission(&init_user_ns, inode,
2409 			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2410 
2411 	/* Allow read access to binaries even when mode 111 */
2412 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2413 	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2414 	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2415 		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
2416 
2417 	return err? nfserrno(err) : 0;
2418 }
2419