xref: /linux/fs/nfsd/vfs.c (revision a4eb44a6435d6d8f9e642407a4a06f65eb90ca04)
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 #include "xdr4.h"
44 #endif /* CONFIG_NFSD_V4 */
45 
46 #include "nfsd.h"
47 #include "vfs.h"
48 #include "filecache.h"
49 #include "trace.h"
50 
51 #define NFSDDBG_FACILITY		NFSDDBG_FILEOP
52 
53 /*
54  * Called from nfsd_lookup and encode_dirent. Check if we have crossed
55  * a mount point.
56  * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
57  *  or nfs_ok having possibly changed *dpp and *expp
58  */
59 int
60 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
61 		        struct svc_export **expp)
62 {
63 	struct svc_export *exp = *expp, *exp2 = NULL;
64 	struct dentry *dentry = *dpp;
65 	struct path path = {.mnt = mntget(exp->ex_path.mnt),
66 			    .dentry = dget(dentry)};
67 	int err = 0;
68 
69 	err = follow_down(&path);
70 	if (err < 0)
71 		goto out;
72 	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
73 	    nfsd_mountpoint(dentry, exp) == 2) {
74 		/* This is only a mountpoint in some other namespace */
75 		path_put(&path);
76 		goto out;
77 	}
78 
79 	exp2 = rqst_exp_get_by_name(rqstp, &path);
80 	if (IS_ERR(exp2)) {
81 		err = PTR_ERR(exp2);
82 		/*
83 		 * We normally allow NFS clients to continue
84 		 * "underneath" a mountpoint that is not exported.
85 		 * The exception is V4ROOT, where no traversal is ever
86 		 * allowed without an explicit export of the new
87 		 * directory.
88 		 */
89 		if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
90 			err = 0;
91 		path_put(&path);
92 		goto out;
93 	}
94 	if (nfsd_v4client(rqstp) ||
95 		(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
96 		/* successfully crossed mount point */
97 		/*
98 		 * This is subtle: path.dentry is *not* on path.mnt
99 		 * at this point.  The only reason we are safe is that
100 		 * original mnt is pinned down by exp, so we should
101 		 * put path *before* putting exp
102 		 */
103 		*dpp = path.dentry;
104 		path.dentry = dentry;
105 		*expp = exp2;
106 		exp2 = exp;
107 	}
108 	path_put(&path);
109 	exp_put(exp2);
110 out:
111 	return err;
112 }
113 
114 static void follow_to_parent(struct path *path)
115 {
116 	struct dentry *dp;
117 
118 	while (path->dentry == path->mnt->mnt_root && follow_up(path))
119 		;
120 	dp = dget_parent(path->dentry);
121 	dput(path->dentry);
122 	path->dentry = dp;
123 }
124 
125 static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
126 {
127 	struct svc_export *exp2;
128 	struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
129 			    .dentry = dget(dparent)};
130 
131 	follow_to_parent(&path);
132 
133 	exp2 = rqst_exp_parent(rqstp, &path);
134 	if (PTR_ERR(exp2) == -ENOENT) {
135 		*dentryp = dget(dparent);
136 	} else if (IS_ERR(exp2)) {
137 		path_put(&path);
138 		return PTR_ERR(exp2);
139 	} else {
140 		*dentryp = dget(path.dentry);
141 		exp_put(*exp);
142 		*exp = exp2;
143 	}
144 	path_put(&path);
145 	return 0;
146 }
147 
148 /*
149  * For nfsd purposes, we treat V4ROOT exports as though there was an
150  * export at *every* directory.
151  * We return:
152  * '1' if this dentry *must* be an export point,
153  * '2' if it might be, if there is really a mount here, and
154  * '0' if there is no chance of an export point here.
155  */
156 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
157 {
158 	if (!d_inode(dentry))
159 		return 0;
160 	if (exp->ex_flags & NFSEXP_V4ROOT)
161 		return 1;
162 	if (nfsd4_is_junction(dentry))
163 		return 1;
164 	if (d_mountpoint(dentry))
165 		/*
166 		 * Might only be a mountpoint in a different namespace,
167 		 * but we need to check.
168 		 */
169 		return 2;
170 	return 0;
171 }
172 
173 __be32
174 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
175 		   const char *name, unsigned int len,
176 		   struct svc_export **exp_ret, struct dentry **dentry_ret)
177 {
178 	struct svc_export	*exp;
179 	struct dentry		*dparent;
180 	struct dentry		*dentry;
181 	int			host_err;
182 
183 	dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
184 
185 	dparent = fhp->fh_dentry;
186 	exp = exp_get(fhp->fh_export);
187 
188 	/* Lookup the name, but don't follow links */
189 	if (isdotent(name, len)) {
190 		if (len==1)
191 			dentry = dget(dparent);
192 		else if (dparent != exp->ex_path.dentry)
193 			dentry = dget_parent(dparent);
194 		else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
195 			dentry = dget(dparent); /* .. == . just like at / */
196 		else {
197 			/* checking mountpoint crossing is very different when stepping up */
198 			host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
199 			if (host_err)
200 				goto out_nfserr;
201 		}
202 	} else {
203 		/*
204 		 * In the nfsd4_open() case, this may be held across
205 		 * subsequent open and delegation acquisition which may
206 		 * need to take the child's i_mutex:
207 		 */
208 		fh_lock_nested(fhp, I_MUTEX_PARENT);
209 		dentry = lookup_one_len(name, dparent, len);
210 		host_err = PTR_ERR(dentry);
211 		if (IS_ERR(dentry))
212 			goto out_nfserr;
213 		if (nfsd_mountpoint(dentry, exp)) {
214 			/*
215 			 * We don't need the i_mutex after all.  It's
216 			 * still possible we could open this (regular
217 			 * files can be mountpoints too), but the
218 			 * i_mutex is just there to prevent renames of
219 			 * something that we might be about to delegate,
220 			 * and a mountpoint won't be renamed:
221 			 */
222 			fh_unlock(fhp);
223 			if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
224 				dput(dentry);
225 				goto out_nfserr;
226 			}
227 		}
228 	}
229 	*dentry_ret = dentry;
230 	*exp_ret = exp;
231 	return 0;
232 
233 out_nfserr:
234 	exp_put(exp);
235 	return nfserrno(host_err);
236 }
237 
238 /*
239  * Look up one component of a pathname.
240  * N.B. After this call _both_ fhp and resfh need an fh_put
241  *
242  * If the lookup would cross a mountpoint, and the mounted filesystem
243  * is exported to the client with NFSEXP_NOHIDE, then the lookup is
244  * accepted as it stands and the mounted directory is
245  * returned. Otherwise the covered directory is returned.
246  * NOTE: this mountpoint crossing is not supported properly by all
247  *   clients and is explicitly disallowed for NFSv3
248  *      NeilBrown <neilb@cse.unsw.edu.au>
249  */
250 __be32
251 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
252 				unsigned int len, struct svc_fh *resfh)
253 {
254 	struct svc_export	*exp;
255 	struct dentry		*dentry;
256 	__be32 err;
257 
258 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
259 	if (err)
260 		return err;
261 	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
262 	if (err)
263 		return err;
264 	err = check_nfsd_access(exp, rqstp);
265 	if (err)
266 		goto out;
267 	/*
268 	 * Note: we compose the file handle now, but as the
269 	 * dentry may be negative, it may need to be updated.
270 	 */
271 	err = fh_compose(resfh, exp, dentry, fhp);
272 	if (!err && d_really_is_negative(dentry))
273 		err = nfserr_noent;
274 out:
275 	dput(dentry);
276 	exp_put(exp);
277 	return err;
278 }
279 
280 /*
281  * Commit metadata changes to stable storage.
282  */
283 static int
284 commit_inode_metadata(struct inode *inode)
285 {
286 	const struct export_operations *export_ops = inode->i_sb->s_export_op;
287 
288 	if (export_ops->commit_metadata)
289 		return export_ops->commit_metadata(inode);
290 	return sync_inode_metadata(inode, 1);
291 }
292 
293 static int
294 commit_metadata(struct svc_fh *fhp)
295 {
296 	struct inode *inode = d_inode(fhp->fh_dentry);
297 
298 	if (!EX_ISSYNC(fhp->fh_export))
299 		return 0;
300 	return commit_inode_metadata(inode);
301 }
302 
303 /*
304  * Go over the attributes and take care of the small differences between
305  * NFS semantics and what Linux expects.
306  */
307 static void
308 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
309 {
310 	/* sanitize the mode change */
311 	if (iap->ia_valid & ATTR_MODE) {
312 		iap->ia_mode &= S_IALLUGO;
313 		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
314 	}
315 
316 	/* Revoke setuid/setgid on chown */
317 	if (!S_ISDIR(inode->i_mode) &&
318 	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
319 		iap->ia_valid |= ATTR_KILL_PRIV;
320 		if (iap->ia_valid & ATTR_MODE) {
321 			/* we're setting mode too, just clear the s*id bits */
322 			iap->ia_mode &= ~S_ISUID;
323 			if (iap->ia_mode & S_IXGRP)
324 				iap->ia_mode &= ~S_ISGID;
325 		} else {
326 			/* set ATTR_KILL_* bits and let VFS handle it */
327 			iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
328 		}
329 	}
330 }
331 
332 static __be32
333 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
334 		struct iattr *iap)
335 {
336 	struct inode *inode = d_inode(fhp->fh_dentry);
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 	return nfserrno(get_write_access(inode));
347 }
348 
349 /*
350  * Set various file attributes.  After this call fhp needs an fh_put.
351  */
352 __be32
353 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
354 	     int check_guard, time64_t guardtime)
355 {
356 	struct dentry	*dentry;
357 	struct inode	*inode;
358 	int		accmode = NFSD_MAY_SATTR;
359 	umode_t		ftype = 0;
360 	__be32		err;
361 	int		host_err;
362 	bool		get_write_count;
363 	bool		size_change = (iap->ia_valid & ATTR_SIZE);
364 
365 	if (iap->ia_valid & ATTR_SIZE) {
366 		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
367 		ftype = S_IFREG;
368 	}
369 
370 	/*
371 	 * If utimes(2) and friends are called with times not NULL, we should
372 	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
373 	 * will return EACCES, when the caller's effective UID does not match
374 	 * the owner of the file, and the caller is not privileged. In this
375 	 * situation, we should return EPERM(notify_change will return this).
376 	 */
377 	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
378 		accmode |= NFSD_MAY_OWNER_OVERRIDE;
379 		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
380 			accmode |= NFSD_MAY_WRITE;
381 	}
382 
383 	/* Callers that do fh_verify should do the fh_want_write: */
384 	get_write_count = !fhp->fh_dentry;
385 
386 	/* Get inode */
387 	err = fh_verify(rqstp, fhp, ftype, accmode);
388 	if (err)
389 		return err;
390 	if (get_write_count) {
391 		host_err = fh_want_write(fhp);
392 		if (host_err)
393 			goto out;
394 	}
395 
396 	dentry = fhp->fh_dentry;
397 	inode = d_inode(dentry);
398 
399 	/* Ignore any mode updates on symlinks */
400 	if (S_ISLNK(inode->i_mode))
401 		iap->ia_valid &= ~ATTR_MODE;
402 
403 	if (!iap->ia_valid)
404 		return 0;
405 
406 	nfsd_sanitize_attrs(inode, iap);
407 
408 	if (check_guard && guardtime != inode->i_ctime.tv_sec)
409 		return nfserr_notsync;
410 
411 	/*
412 	 * The size case is special, it changes the file in addition to the
413 	 * attributes, and file systems don't expect it to be mixed with
414 	 * "random" attribute changes.  We thus split out the size change
415 	 * into a separate call to ->setattr, and do the rest as a separate
416 	 * setattr call.
417 	 */
418 	if (size_change) {
419 		err = nfsd_get_write_access(rqstp, fhp, iap);
420 		if (err)
421 			return err;
422 	}
423 
424 	fh_lock(fhp);
425 	if (size_change) {
426 		/*
427 		 * RFC5661, Section 18.30.4:
428 		 *   Changing the size of a file with SETATTR indirectly
429 		 *   changes the time_modify and change attributes.
430 		 *
431 		 * (and similar for the older RFCs)
432 		 */
433 		struct iattr size_attr = {
434 			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
435 			.ia_size	= iap->ia_size,
436 		};
437 
438 		host_err = -EFBIG;
439 		if (iap->ia_size < 0)
440 			goto out_unlock;
441 
442 		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
443 		if (host_err)
444 			goto out_unlock;
445 		iap->ia_valid &= ~ATTR_SIZE;
446 
447 		/*
448 		 * Avoid the additional setattr call below if the only other
449 		 * attribute that the client sends is the mtime, as we update
450 		 * it as part of the size change above.
451 		 */
452 		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
453 			goto out_unlock;
454 	}
455 
456 	iap->ia_valid |= ATTR_CTIME;
457 	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
458 
459 out_unlock:
460 	fh_unlock(fhp);
461 	if (size_change)
462 		put_write_access(inode);
463 out:
464 	if (!host_err)
465 		host_err = commit_metadata(fhp);
466 	return nfserrno(host_err);
467 }
468 
469 #if defined(CONFIG_NFSD_V4)
470 /*
471  * NFS junction information is stored in an extended attribute.
472  */
473 #define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
474 
475 /**
476  * nfsd4_is_junction - Test if an object could be an NFS junction
477  *
478  * @dentry: object to test
479  *
480  * Returns 1 if "dentry" appears to contain NFS junction information.
481  * Otherwise 0 is returned.
482  */
483 int nfsd4_is_junction(struct dentry *dentry)
484 {
485 	struct inode *inode = d_inode(dentry);
486 
487 	if (inode == NULL)
488 		return 0;
489 	if (inode->i_mode & S_IXUGO)
490 		return 0;
491 	if (!(inode->i_mode & S_ISVTX))
492 		return 0;
493 	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
494 			 NULL, 0) <= 0)
495 		return 0;
496 	return 1;
497 }
498 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
499 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
500 		struct xdr_netobj *label)
501 {
502 	__be32 error;
503 	int host_error;
504 	struct dentry *dentry;
505 
506 	error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
507 	if (error)
508 		return error;
509 
510 	dentry = fhp->fh_dentry;
511 
512 	inode_lock(d_inode(dentry));
513 	host_error = security_inode_setsecctx(dentry, label->data, label->len);
514 	inode_unlock(d_inode(dentry));
515 	return nfserrno(host_error);
516 }
517 #else
518 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
519 		struct xdr_netobj *label)
520 {
521 	return nfserr_notsupp;
522 }
523 #endif
524 
525 static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
526 {
527 	return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
528 }
529 
530 __be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
531 		struct nfsd_file *nf_src, u64 src_pos,
532 		struct nfsd_file *nf_dst, u64 dst_pos,
533 		u64 count, bool sync)
534 {
535 	struct file *src = nf_src->nf_file;
536 	struct file *dst = nf_dst->nf_file;
537 	errseq_t since;
538 	loff_t cloned;
539 	__be32 ret = 0;
540 
541 	since = READ_ONCE(dst->f_wb_err);
542 	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
543 	if (cloned < 0) {
544 		ret = nfserrno(cloned);
545 		goto out_err;
546 	}
547 	if (count && cloned != count) {
548 		ret = nfserrno(-EINVAL);
549 		goto out_err;
550 	}
551 	if (sync) {
552 		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
553 		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
554 
555 		if (!status)
556 			status = filemap_check_wb_err(dst->f_mapping, since);
557 		if (!status)
558 			status = commit_inode_metadata(file_inode(src));
559 		if (status < 0) {
560 			struct nfsd_net *nn = net_generic(nf_dst->nf_net,
561 							  nfsd_net_id);
562 
563 			trace_nfsd_clone_file_range_err(rqstp,
564 					&nfsd4_get_cstate(rqstp)->save_fh,
565 					src_pos,
566 					&nfsd4_get_cstate(rqstp)->current_fh,
567 					dst_pos,
568 					count, status);
569 			nfsd_reset_write_verifier(nn);
570 			trace_nfsd_writeverf_reset(nn, rqstp, status);
571 			ret = nfserrno(status);
572 		}
573 	}
574 out_err:
575 	return ret;
576 }
577 
578 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
579 			     u64 dst_pos, u64 count)
580 {
581 
582 	/*
583 	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
584 	 * thread and client rpc slot.  The choice of 4MB is somewhat
585 	 * arbitrary.  We might instead base this on r/wsize, or make it
586 	 * tunable, or use a time instead of a byte limit, or implement
587 	 * asynchronous copy.  In theory a client could also recognize a
588 	 * limit like this and pipeline multiple COPY requests.
589 	 */
590 	count = min_t(u64, count, 1 << 22);
591 	return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
592 }
593 
594 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
595 			   struct file *file, loff_t offset, loff_t len,
596 			   int flags)
597 {
598 	int error;
599 
600 	if (!S_ISREG(file_inode(file)->i_mode))
601 		return nfserr_inval;
602 
603 	error = vfs_fallocate(file, flags, offset, len);
604 	if (!error)
605 		error = commit_metadata(fhp);
606 
607 	return nfserrno(error);
608 }
609 #endif /* defined(CONFIG_NFSD_V4) */
610 
611 #ifdef CONFIG_NFSD_V3
612 /*
613  * Check server access rights to a file system object
614  */
615 struct accessmap {
616 	u32		access;
617 	int		how;
618 };
619 static struct accessmap	nfs3_regaccess[] = {
620     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
621     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
622     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
623     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
624 
625 #ifdef CONFIG_NFSD_V4
626     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
627     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
628     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
629 #endif
630 
631     {	0,			0				}
632 };
633 
634 static struct accessmap	nfs3_diraccess[] = {
635     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
636     {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
637     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
638     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
639     {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
640 
641 #ifdef CONFIG_NFSD_V4
642     {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
643     {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
644     {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
645 #endif
646 
647     {	0,			0				}
648 };
649 
650 static struct accessmap	nfs3_anyaccess[] = {
651 	/* Some clients - Solaris 2.6 at least, make an access call
652 	 * to the server to check for access for things like /dev/null
653 	 * (which really, the server doesn't care about).  So
654 	 * We provide simple access checking for them, looking
655 	 * mainly at mode bits, and we make sure to ignore read-only
656 	 * filesystem checks
657 	 */
658     {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
659     {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
660     {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
661     {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
662 
663     {	0,			0				}
664 };
665 
666 __be32
667 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
668 {
669 	struct accessmap	*map;
670 	struct svc_export	*export;
671 	struct dentry		*dentry;
672 	u32			query, result = 0, sresult = 0;
673 	__be32			error;
674 
675 	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
676 	if (error)
677 		goto out;
678 
679 	export = fhp->fh_export;
680 	dentry = fhp->fh_dentry;
681 
682 	if (d_is_reg(dentry))
683 		map = nfs3_regaccess;
684 	else if (d_is_dir(dentry))
685 		map = nfs3_diraccess;
686 	else
687 		map = nfs3_anyaccess;
688 
689 
690 	query = *access;
691 	for  (; map->access; map++) {
692 		if (map->access & query) {
693 			__be32 err2;
694 
695 			sresult |= map->access;
696 
697 			err2 = nfsd_permission(rqstp, export, dentry, map->how);
698 			switch (err2) {
699 			case nfs_ok:
700 				result |= map->access;
701 				break;
702 
703 			/* the following error codes just mean the access was not allowed,
704 			 * rather than an error occurred */
705 			case nfserr_rofs:
706 			case nfserr_acces:
707 			case nfserr_perm:
708 				/* simply don't "or" in the access bit. */
709 				break;
710 			default:
711 				error = err2;
712 				goto out;
713 			}
714 		}
715 	}
716 	*access = result;
717 	if (supported)
718 		*supported = sresult;
719 
720  out:
721 	return error;
722 }
723 #endif /* CONFIG_NFSD_V3 */
724 
725 int nfsd_open_break_lease(struct inode *inode, int access)
726 {
727 	unsigned int mode;
728 
729 	if (access & NFSD_MAY_NOT_BREAK_LEASE)
730 		return 0;
731 	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
732 	return break_lease(inode, mode | O_NONBLOCK);
733 }
734 
735 /*
736  * Open an existing file or directory.
737  * The may_flags argument indicates the type of open (read/write/lock)
738  * and additional flags.
739  * N.B. After this call fhp needs an fh_put
740  */
741 static __be32
742 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
743 			int may_flags, struct file **filp)
744 {
745 	struct path	path;
746 	struct inode	*inode;
747 	struct file	*file;
748 	int		flags = O_RDONLY|O_LARGEFILE;
749 	__be32		err;
750 	int		host_err = 0;
751 
752 	path.mnt = fhp->fh_export->ex_path.mnt;
753 	path.dentry = fhp->fh_dentry;
754 	inode = d_inode(path.dentry);
755 
756 	err = nfserr_perm;
757 	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
758 		goto out;
759 
760 	if (!inode->i_fop)
761 		goto out;
762 
763 	host_err = nfsd_open_break_lease(inode, may_flags);
764 	if (host_err) /* NOMEM or WOULDBLOCK */
765 		goto out_nfserr;
766 
767 	if (may_flags & NFSD_MAY_WRITE) {
768 		if (may_flags & NFSD_MAY_READ)
769 			flags = O_RDWR|O_LARGEFILE;
770 		else
771 			flags = O_WRONLY|O_LARGEFILE;
772 	}
773 
774 	file = dentry_open(&path, flags, current_cred());
775 	if (IS_ERR(file)) {
776 		host_err = PTR_ERR(file);
777 		goto out_nfserr;
778 	}
779 
780 	host_err = ima_file_check(file, may_flags);
781 	if (host_err) {
782 		fput(file);
783 		goto out_nfserr;
784 	}
785 
786 	if (may_flags & NFSD_MAY_64BIT_COOKIE)
787 		file->f_mode |= FMODE_64BITHASH;
788 	else
789 		file->f_mode |= FMODE_32BITHASH;
790 
791 	*filp = file;
792 out_nfserr:
793 	err = nfserrno(host_err);
794 out:
795 	return err;
796 }
797 
798 __be32
799 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
800 		int may_flags, struct file **filp)
801 {
802 	__be32 err;
803 	bool retried = false;
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 retry:
820 	err = fh_verify(rqstp, fhp, type, may_flags);
821 	if (!err) {
822 		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
823 		if (err == nfserr_stale && !retried) {
824 			retried = true;
825 			fh_put(fhp);
826 			goto retry;
827 		}
828 	}
829 	validate_process_creds();
830 	return err;
831 }
832 
833 __be32
834 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
835 		int may_flags, struct file **filp)
836 {
837 	__be32 err;
838 
839 	validate_process_creds();
840 	err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
841 	validate_process_creds();
842 	return err;
843 }
844 
845 /*
846  * Grab and keep cached pages associated with a file in the svc_rqst
847  * so that they can be passed to the network sendmsg/sendpage routines
848  * directly. They will be released after the sending has completed.
849  */
850 static int
851 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
852 		  struct splice_desc *sd)
853 {
854 	struct svc_rqst *rqstp = sd->u.data;
855 	struct page **pp = rqstp->rq_next_page;
856 	struct page *page = buf->page;
857 
858 	if (rqstp->rq_res.page_len == 0) {
859 		svc_rqst_replace_page(rqstp, page);
860 		rqstp->rq_res.page_base = buf->offset;
861 	} else if (page != pp[-1]) {
862 		svc_rqst_replace_page(rqstp, page);
863 	}
864 	rqstp->rq_res.page_len += sd->len;
865 
866 	return sd->len;
867 }
868 
869 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
870 				    struct splice_desc *sd)
871 {
872 	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
873 }
874 
875 static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
876 		size_t expected)
877 {
878 	if (expected != 0 && len == 0)
879 		return 1;
880 	if (offset+len >= i_size_read(file_inode(file)))
881 		return 1;
882 	return 0;
883 }
884 
885 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
886 			       struct file *file, loff_t offset,
887 			       unsigned long *count, u32 *eof, ssize_t host_err)
888 {
889 	if (host_err >= 0) {
890 		nfsd_stats_io_read_add(fhp->fh_export, host_err);
891 		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
892 		*count = host_err;
893 		fsnotify_access(file);
894 		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
895 		return 0;
896 	} else {
897 		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
898 		return nfserrno(host_err);
899 	}
900 }
901 
902 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
903 			struct file *file, loff_t offset, unsigned long *count,
904 			u32 *eof)
905 {
906 	struct splice_desc sd = {
907 		.len		= 0,
908 		.total_len	= *count,
909 		.pos		= offset,
910 		.u.data		= rqstp,
911 	};
912 	ssize_t host_err;
913 
914 	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
915 	rqstp->rq_next_page = rqstp->rq_respages + 1;
916 	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
917 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
918 }
919 
920 __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
921 		  struct file *file, loff_t offset,
922 		  struct kvec *vec, int vlen, unsigned long *count,
923 		  u32 *eof)
924 {
925 	struct iov_iter iter;
926 	loff_t ppos = offset;
927 	ssize_t host_err;
928 
929 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
930 	iov_iter_kvec(&iter, READ, vec, vlen, *count);
931 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
932 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
933 }
934 
935 /*
936  * Gathered writes: If another process is currently writing to the file,
937  * there's a high chance this is another nfsd (triggered by a bulk write
938  * from a client's biod). Rather than syncing the file with each write
939  * request, we sleep for 10 msec.
940  *
941  * I don't know if this roughly approximates C. Juszak's idea of
942  * gathered writes, but it's a nice and simple solution (IMHO), and it
943  * seems to work:-)
944  *
945  * Note: we do this only in the NFSv2 case, since v3 and higher have a
946  * better tool (separate unstable writes and commits) for solving this
947  * problem.
948  */
949 static int wait_for_concurrent_writes(struct file *file)
950 {
951 	struct inode *inode = file_inode(file);
952 	static ino_t last_ino;
953 	static dev_t last_dev;
954 	int err = 0;
955 
956 	if (atomic_read(&inode->i_writecount) > 1
957 	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
958 		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
959 		msleep(10);
960 		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
961 	}
962 
963 	if (inode->i_state & I_DIRTY) {
964 		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
965 		err = vfs_fsync(file, 0);
966 	}
967 	last_ino = inode->i_ino;
968 	last_dev = inode->i_sb->s_dev;
969 	return err;
970 }
971 
972 __be32
973 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
974 				loff_t offset, struct kvec *vec, int vlen,
975 				unsigned long *cnt, int stable,
976 				__be32 *verf)
977 {
978 	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
979 	struct file		*file = nf->nf_file;
980 	struct super_block	*sb = file_inode(file)->i_sb;
981 	struct svc_export	*exp;
982 	struct iov_iter		iter;
983 	errseq_t		since;
984 	__be32			nfserr;
985 	int			host_err;
986 	int			use_wgather;
987 	loff_t			pos = offset;
988 	unsigned long		exp_op_flags = 0;
989 	unsigned int		pflags = current->flags;
990 	rwf_t			flags = 0;
991 	bool			restore_flags = false;
992 
993 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
994 
995 	if (sb->s_export_op)
996 		exp_op_flags = sb->s_export_op->flags;
997 
998 	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
999 	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1000 		/*
1001 		 * We want throttling in balance_dirty_pages()
1002 		 * and shrink_inactive_list() to only consider
1003 		 * the backingdev we are writing to, so that nfs to
1004 		 * localhost doesn't cause nfsd to lock up due to all
1005 		 * the client's dirty pages or its congested queue.
1006 		 */
1007 		current->flags |= PF_LOCAL_THROTTLE;
1008 		restore_flags = true;
1009 	}
1010 
1011 	exp = fhp->fh_export;
1012 	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1013 
1014 	if (!EX_ISSYNC(exp))
1015 		stable = NFS_UNSTABLE;
1016 
1017 	if (stable && !use_wgather)
1018 		flags |= RWF_SYNC;
1019 
1020 	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
1021 	since = READ_ONCE(file->f_wb_err);
1022 	if (verf)
1023 		nfsd_copy_write_verifier(verf, nn);
1024 	host_err = vfs_iter_write(file, &iter, &pos, flags);
1025 	if (host_err < 0) {
1026 		nfsd_reset_write_verifier(nn);
1027 		trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1028 		goto out_nfserr;
1029 	}
1030 	*cnt = host_err;
1031 	nfsd_stats_io_write_add(exp, *cnt);
1032 	fsnotify_modify(file);
1033 	host_err = filemap_check_wb_err(file->f_mapping, since);
1034 	if (host_err < 0)
1035 		goto out_nfserr;
1036 
1037 	if (stable && use_wgather) {
1038 		host_err = wait_for_concurrent_writes(file);
1039 		if (host_err < 0) {
1040 			nfsd_reset_write_verifier(nn);
1041 			trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1042 		}
1043 	}
1044 
1045 out_nfserr:
1046 	if (host_err >= 0) {
1047 		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1048 		nfserr = nfs_ok;
1049 	} else {
1050 		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1051 		nfserr = nfserrno(host_err);
1052 	}
1053 	if (restore_flags)
1054 		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1055 	return nfserr;
1056 }
1057 
1058 /*
1059  * Read data from a file. count must contain the requested read count
1060  * on entry. On return, *count contains the number of bytes actually read.
1061  * N.B. After this call fhp needs an fh_put
1062  */
1063 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1064 	loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
1065 	u32 *eof)
1066 {
1067 	struct nfsd_file	*nf;
1068 	struct file *file;
1069 	__be32 err;
1070 
1071 	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1072 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
1073 	if (err)
1074 		return err;
1075 
1076 	file = nf->nf_file;
1077 	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1078 		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1079 	else
1080 		err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
1081 
1082 	nfsd_file_put(nf);
1083 
1084 	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1085 
1086 	return err;
1087 }
1088 
1089 /*
1090  * Write data to a file.
1091  * The stable flag requests synchronous writes.
1092  * N.B. After this call fhp needs an fh_put
1093  */
1094 __be32
1095 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1096 	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1097 	   __be32 *verf)
1098 {
1099 	struct nfsd_file *nf;
1100 	__be32 err;
1101 
1102 	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1103 
1104 	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1105 	if (err)
1106 		goto out;
1107 
1108 	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1109 			vlen, cnt, stable, verf);
1110 	nfsd_file_put(nf);
1111 out:
1112 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1113 	return err;
1114 }
1115 
1116 #ifdef CONFIG_NFSD_V3
1117 /**
1118  * nfsd_commit - Commit pending writes to stable storage
1119  * @rqstp: RPC request being processed
1120  * @fhp: NFS filehandle
1121  * @offset: raw offset from beginning of file
1122  * @count: raw count of bytes to sync
1123  * @verf: filled in with the server's current write verifier
1124  *
1125  * Note: we guarantee that data that lies within the range specified
1126  * by the 'offset' and 'count' parameters will be synced. The server
1127  * is permitted to sync data that lies outside this range at the
1128  * same time.
1129  *
1130  * Unfortunately we cannot lock the file to make sure we return full WCC
1131  * data to the client, as locking happens lower down in the filesystem.
1132  *
1133  * Return values:
1134  *   An nfsstat value in network byte order.
1135  */
1136 __be32
1137 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, u64 offset,
1138 	    u32 count, __be32 *verf)
1139 {
1140 	u64			maxbytes;
1141 	loff_t			start, end;
1142 	struct nfsd_net		*nn;
1143 	struct nfsd_file	*nf;
1144 	__be32			err;
1145 
1146 	err = nfsd_file_acquire(rqstp, fhp,
1147 			NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
1148 	if (err)
1149 		goto out;
1150 
1151 	/*
1152 	 * Convert the client-provided (offset, count) range to a
1153 	 * (start, end) range. If the client-provided range falls
1154 	 * outside the maximum file size of the underlying FS,
1155 	 * clamp the sync range appropriately.
1156 	 */
1157 	start = 0;
1158 	end = LLONG_MAX;
1159 	maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
1160 	if (offset < maxbytes) {
1161 		start = offset;
1162 		if (count && (offset + count - 1 < maxbytes))
1163 			end = offset + count - 1;
1164 	}
1165 
1166 	nn = net_generic(nf->nf_net, nfsd_net_id);
1167 	if (EX_ISSYNC(fhp->fh_export)) {
1168 		errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
1169 		int err2;
1170 
1171 		err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
1172 		switch (err2) {
1173 		case 0:
1174 			nfsd_copy_write_verifier(verf, nn);
1175 			err2 = filemap_check_wb_err(nf->nf_file->f_mapping,
1176 						    since);
1177 			break;
1178 		case -EINVAL:
1179 			err = nfserr_notsupp;
1180 			break;
1181 		default:
1182 			nfsd_reset_write_verifier(nn);
1183 			trace_nfsd_writeverf_reset(nn, rqstp, err2);
1184 		}
1185 		err = nfserrno(err2);
1186 	} else
1187 		nfsd_copy_write_verifier(verf, nn);
1188 
1189 	nfsd_file_put(nf);
1190 out:
1191 	return err;
1192 }
1193 #endif /* CONFIG_NFSD_V3 */
1194 
1195 static __be32
1196 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *resfhp,
1197 			struct iattr *iap)
1198 {
1199 	/*
1200 	 * Mode has already been set earlier in create:
1201 	 */
1202 	iap->ia_valid &= ~ATTR_MODE;
1203 	/*
1204 	 * Setting uid/gid works only for root.  Irix appears to
1205 	 * send along the gid on create when it tries to implement
1206 	 * setgid directories via NFS:
1207 	 */
1208 	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1209 		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1210 	if (iap->ia_valid)
1211 		return nfsd_setattr(rqstp, resfhp, iap, 0, (time64_t)0);
1212 	/* Callers expect file metadata to be committed here */
1213 	return nfserrno(commit_metadata(resfhp));
1214 }
1215 
1216 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1217  * setting size to 0 may fail for some specific file systems by the permission
1218  * checking which requires WRITE permission but the mode is 000.
1219  * we ignore the resizing(to 0) on the just new created file, since the size is
1220  * 0 after file created.
1221  *
1222  * call this only after vfs_create() is called.
1223  * */
1224 static void
1225 nfsd_check_ignore_resizing(struct iattr *iap)
1226 {
1227 	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1228 		iap->ia_valid &= ~ATTR_SIZE;
1229 }
1230 
1231 /* The parent directory should already be locked: */
1232 __be32
1233 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1234 		char *fname, int flen, struct iattr *iap,
1235 		int type, dev_t rdev, struct svc_fh *resfhp)
1236 {
1237 	struct dentry	*dentry, *dchild;
1238 	struct inode	*dirp;
1239 	__be32		err;
1240 	__be32		err2;
1241 	int		host_err;
1242 
1243 	dentry = fhp->fh_dentry;
1244 	dirp = d_inode(dentry);
1245 
1246 	dchild = dget(resfhp->fh_dentry);
1247 	if (!fhp->fh_locked) {
1248 		WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
1249 				dentry);
1250 		err = nfserr_io;
1251 		goto out;
1252 	}
1253 
1254 	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1255 	if (err)
1256 		goto out;
1257 
1258 	if (!(iap->ia_valid & ATTR_MODE))
1259 		iap->ia_mode = 0;
1260 	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1261 
1262 	if (!IS_POSIXACL(dirp))
1263 		iap->ia_mode &= ~current_umask();
1264 
1265 	err = 0;
1266 	host_err = 0;
1267 	switch (type) {
1268 	case S_IFREG:
1269 		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1270 		if (!host_err)
1271 			nfsd_check_ignore_resizing(iap);
1272 		break;
1273 	case S_IFDIR:
1274 		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
1275 		if (!host_err && unlikely(d_unhashed(dchild))) {
1276 			struct dentry *d;
1277 			d = lookup_one_len(dchild->d_name.name,
1278 					   dchild->d_parent,
1279 					   dchild->d_name.len);
1280 			if (IS_ERR(d)) {
1281 				host_err = PTR_ERR(d);
1282 				break;
1283 			}
1284 			if (unlikely(d_is_negative(d))) {
1285 				dput(d);
1286 				err = nfserr_serverfault;
1287 				goto out;
1288 			}
1289 			dput(resfhp->fh_dentry);
1290 			resfhp->fh_dentry = dget(d);
1291 			err = fh_update(resfhp);
1292 			dput(dchild);
1293 			dchild = d;
1294 			if (err)
1295 				goto out;
1296 		}
1297 		break;
1298 	case S_IFCHR:
1299 	case S_IFBLK:
1300 	case S_IFIFO:
1301 	case S_IFSOCK:
1302 		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
1303 				     iap->ia_mode, rdev);
1304 		break;
1305 	default:
1306 		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1307 		       type);
1308 		host_err = -EINVAL;
1309 	}
1310 	if (host_err < 0)
1311 		goto out_nfserr;
1312 
1313 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1314 
1315 	/*
1316 	 * nfsd_create_setattr already committed the child.  Transactional
1317 	 * filesystems had a chance to commit changes for both parent and
1318 	 * child simultaneously making the following commit_metadata a
1319 	 * noop.
1320 	 */
1321 	err2 = nfserrno(commit_metadata(fhp));
1322 	if (err2)
1323 		err = err2;
1324 	/*
1325 	 * Update the file handle to get the new inode info.
1326 	 */
1327 	if (!err)
1328 		err = fh_update(resfhp);
1329 out:
1330 	dput(dchild);
1331 	return err;
1332 
1333 out_nfserr:
1334 	err = nfserrno(host_err);
1335 	goto out;
1336 }
1337 
1338 /*
1339  * Create a filesystem object (regular, directory, special).
1340  * Note that the parent directory is left locked.
1341  *
1342  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1343  */
1344 __be32
1345 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1346 		char *fname, int flen, struct iattr *iap,
1347 		int type, dev_t rdev, struct svc_fh *resfhp)
1348 {
1349 	struct dentry	*dentry, *dchild = NULL;
1350 	__be32		err;
1351 	int		host_err;
1352 
1353 	if (isdotent(fname, flen))
1354 		return nfserr_exist;
1355 
1356 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1357 	if (err)
1358 		return err;
1359 
1360 	dentry = fhp->fh_dentry;
1361 
1362 	host_err = fh_want_write(fhp);
1363 	if (host_err)
1364 		return nfserrno(host_err);
1365 
1366 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1367 	dchild = lookup_one_len(fname, dentry, flen);
1368 	host_err = PTR_ERR(dchild);
1369 	if (IS_ERR(dchild))
1370 		return nfserrno(host_err);
1371 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1372 	/*
1373 	 * We unconditionally drop our ref to dchild as fh_compose will have
1374 	 * already grabbed its own ref for it.
1375 	 */
1376 	dput(dchild);
1377 	if (err)
1378 		return err;
1379 	return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
1380 					rdev, resfhp);
1381 }
1382 
1383 #ifdef CONFIG_NFSD_V3
1384 
1385 /*
1386  * NFSv3 and NFSv4 version of nfsd_create
1387  */
1388 __be32
1389 do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1390 		char *fname, int flen, struct iattr *iap,
1391 		struct svc_fh *resfhp, int createmode, u32 *verifier,
1392 	        bool *truncp, bool *created)
1393 {
1394 	struct dentry	*dentry, *dchild = NULL;
1395 	struct inode	*dirp;
1396 	__be32		err;
1397 	int		host_err;
1398 	__u32		v_mtime=0, v_atime=0;
1399 
1400 	err = nfserr_perm;
1401 	if (!flen)
1402 		goto out;
1403 	err = nfserr_exist;
1404 	if (isdotent(fname, flen))
1405 		goto out;
1406 	if (!(iap->ia_valid & ATTR_MODE))
1407 		iap->ia_mode = 0;
1408 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
1409 	if (err)
1410 		goto out;
1411 
1412 	dentry = fhp->fh_dentry;
1413 	dirp = d_inode(dentry);
1414 
1415 	host_err = fh_want_write(fhp);
1416 	if (host_err)
1417 		goto out_nfserr;
1418 
1419 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1420 
1421 	/*
1422 	 * Compose the response file handle.
1423 	 */
1424 	dchild = lookup_one_len(fname, dentry, flen);
1425 	host_err = PTR_ERR(dchild);
1426 	if (IS_ERR(dchild))
1427 		goto out_nfserr;
1428 
1429 	/* If file doesn't exist, check for permissions to create one */
1430 	if (d_really_is_negative(dchild)) {
1431 		err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1432 		if (err)
1433 			goto out;
1434 	}
1435 
1436 	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1437 	if (err)
1438 		goto out;
1439 
1440 	if (nfsd_create_is_exclusive(createmode)) {
1441 		/* solaris7 gets confused (bugid 4218508) if these have
1442 		 * the high bit set, as do xfs filesystems without the
1443 		 * "bigtime" feature.  So just clear the high bits. If this is
1444 		 * ever changed to use different attrs for storing the
1445 		 * verifier, then do_open_lookup() will also need to be fixed
1446 		 * accordingly.
1447 		 */
1448 		v_mtime = verifier[0]&0x7fffffff;
1449 		v_atime = verifier[1]&0x7fffffff;
1450 	}
1451 
1452 	if (d_really_is_positive(dchild)) {
1453 		err = 0;
1454 
1455 		switch (createmode) {
1456 		case NFS3_CREATE_UNCHECKED:
1457 			if (! d_is_reg(dchild))
1458 				goto out;
1459 			else if (truncp) {
1460 				/* in nfsv4, we need to treat this case a little
1461 				 * differently.  we don't want to truncate the
1462 				 * file now; this would be wrong if the OPEN
1463 				 * fails for some other reason.  furthermore,
1464 				 * if the size is nonzero, we should ignore it
1465 				 * according to spec!
1466 				 */
1467 				*truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
1468 			}
1469 			else {
1470 				iap->ia_valid &= ATTR_SIZE;
1471 				goto set_attr;
1472 			}
1473 			break;
1474 		case NFS3_CREATE_EXCLUSIVE:
1475 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1476 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1477 			    && d_inode(dchild)->i_size  == 0 ) {
1478 				if (created)
1479 					*created = true;
1480 				break;
1481 			}
1482 			fallthrough;
1483 		case NFS4_CREATE_EXCLUSIVE4_1:
1484 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1485 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1486 			    && d_inode(dchild)->i_size  == 0 ) {
1487 				if (created)
1488 					*created = true;
1489 				goto set_attr;
1490 			}
1491 			fallthrough;
1492 		case NFS3_CREATE_GUARDED:
1493 			err = nfserr_exist;
1494 		}
1495 		fh_drop_write(fhp);
1496 		goto out;
1497 	}
1498 
1499 	if (!IS_POSIXACL(dirp))
1500 		iap->ia_mode &= ~current_umask();
1501 
1502 	host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1503 	if (host_err < 0) {
1504 		fh_drop_write(fhp);
1505 		goto out_nfserr;
1506 	}
1507 	if (created)
1508 		*created = true;
1509 
1510 	nfsd_check_ignore_resizing(iap);
1511 
1512 	if (nfsd_create_is_exclusive(createmode)) {
1513 		/* Cram the verifier into atime/mtime */
1514 		iap->ia_valid = ATTR_MTIME|ATTR_ATIME
1515 			| ATTR_MTIME_SET|ATTR_ATIME_SET;
1516 		/* XXX someone who knows this better please fix it for nsec */
1517 		iap->ia_mtime.tv_sec = v_mtime;
1518 		iap->ia_atime.tv_sec = v_atime;
1519 		iap->ia_mtime.tv_nsec = 0;
1520 		iap->ia_atime.tv_nsec = 0;
1521 	}
1522 
1523  set_attr:
1524 	err = nfsd_create_setattr(rqstp, resfhp, iap);
1525 
1526 	/*
1527 	 * nfsd_create_setattr already committed the child
1528 	 * (and possibly also the parent).
1529 	 */
1530 	if (!err)
1531 		err = nfserrno(commit_metadata(fhp));
1532 
1533 	/*
1534 	 * Update the filehandle to get the new inode info.
1535 	 */
1536 	if (!err)
1537 		err = fh_update(resfhp);
1538 
1539  out:
1540 	fh_unlock(fhp);
1541 	if (dchild && !IS_ERR(dchild))
1542 		dput(dchild);
1543 	fh_drop_write(fhp);
1544  	return err;
1545 
1546  out_nfserr:
1547 	err = nfserrno(host_err);
1548 	goto out;
1549 }
1550 #endif /* CONFIG_NFSD_V3 */
1551 
1552 /*
1553  * Read a symlink. On entry, *lenp must contain the maximum path length that
1554  * fits into the buffer. On return, it contains the true length.
1555  * N.B. After this call fhp needs an fh_put
1556  */
1557 __be32
1558 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1559 {
1560 	__be32		err;
1561 	const char *link;
1562 	struct path path;
1563 	DEFINE_DELAYED_CALL(done);
1564 	int len;
1565 
1566 	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1567 	if (unlikely(err))
1568 		return err;
1569 
1570 	path.mnt = fhp->fh_export->ex_path.mnt;
1571 	path.dentry = fhp->fh_dentry;
1572 
1573 	if (unlikely(!d_is_symlink(path.dentry)))
1574 		return nfserr_inval;
1575 
1576 	touch_atime(&path);
1577 
1578 	link = vfs_get_link(path.dentry, &done);
1579 	if (IS_ERR(link))
1580 		return nfserrno(PTR_ERR(link));
1581 
1582 	len = strlen(link);
1583 	if (len < *lenp)
1584 		*lenp = len;
1585 	memcpy(buf, link, *lenp);
1586 	do_delayed_call(&done);
1587 	return 0;
1588 }
1589 
1590 /*
1591  * Create a symlink and look up its inode
1592  * N.B. After this call _both_ fhp and resfhp need an fh_put
1593  */
1594 __be32
1595 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1596 				char *fname, int flen,
1597 				char *path,
1598 				struct svc_fh *resfhp)
1599 {
1600 	struct dentry	*dentry, *dnew;
1601 	__be32		err, cerr;
1602 	int		host_err;
1603 
1604 	err = nfserr_noent;
1605 	if (!flen || path[0] == '\0')
1606 		goto out;
1607 	err = nfserr_exist;
1608 	if (isdotent(fname, flen))
1609 		goto out;
1610 
1611 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1612 	if (err)
1613 		goto out;
1614 
1615 	host_err = fh_want_write(fhp);
1616 	if (host_err)
1617 		goto out_nfserr;
1618 
1619 	fh_lock(fhp);
1620 	dentry = fhp->fh_dentry;
1621 	dnew = lookup_one_len(fname, dentry, flen);
1622 	host_err = PTR_ERR(dnew);
1623 	if (IS_ERR(dnew))
1624 		goto out_nfserr;
1625 
1626 	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
1627 	err = nfserrno(host_err);
1628 	fh_unlock(fhp);
1629 	if (!err)
1630 		err = nfserrno(commit_metadata(fhp));
1631 
1632 	fh_drop_write(fhp);
1633 
1634 	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1635 	dput(dnew);
1636 	if (err==0) err = cerr;
1637 out:
1638 	return err;
1639 
1640 out_nfserr:
1641 	err = nfserrno(host_err);
1642 	goto out;
1643 }
1644 
1645 /*
1646  * Create a hardlink
1647  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1648  */
1649 __be32
1650 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1651 				char *name, int len, struct svc_fh *tfhp)
1652 {
1653 	struct dentry	*ddir, *dnew, *dold;
1654 	struct inode	*dirp;
1655 	__be32		err;
1656 	int		host_err;
1657 
1658 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1659 	if (err)
1660 		goto out;
1661 	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1662 	if (err)
1663 		goto out;
1664 	err = nfserr_isdir;
1665 	if (d_is_dir(tfhp->fh_dentry))
1666 		goto out;
1667 	err = nfserr_perm;
1668 	if (!len)
1669 		goto out;
1670 	err = nfserr_exist;
1671 	if (isdotent(name, len))
1672 		goto out;
1673 
1674 	host_err = fh_want_write(tfhp);
1675 	if (host_err) {
1676 		err = nfserrno(host_err);
1677 		goto out;
1678 	}
1679 
1680 	fh_lock_nested(ffhp, I_MUTEX_PARENT);
1681 	ddir = ffhp->fh_dentry;
1682 	dirp = d_inode(ddir);
1683 
1684 	dnew = lookup_one_len(name, ddir, len);
1685 	host_err = PTR_ERR(dnew);
1686 	if (IS_ERR(dnew))
1687 		goto out_nfserr;
1688 
1689 	dold = tfhp->fh_dentry;
1690 
1691 	err = nfserr_noent;
1692 	if (d_really_is_negative(dold))
1693 		goto out_dput;
1694 	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
1695 	fh_unlock(ffhp);
1696 	if (!host_err) {
1697 		err = nfserrno(commit_metadata(ffhp));
1698 		if (!err)
1699 			err = nfserrno(commit_metadata(tfhp));
1700 	} else {
1701 		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1702 			err = nfserr_acces;
1703 		else
1704 			err = nfserrno(host_err);
1705 	}
1706 out_dput:
1707 	dput(dnew);
1708 out_unlock:
1709 	fh_unlock(ffhp);
1710 	fh_drop_write(tfhp);
1711 out:
1712 	return err;
1713 
1714 out_nfserr:
1715 	err = nfserrno(host_err);
1716 	goto out_unlock;
1717 }
1718 
1719 static void
1720 nfsd_close_cached_files(struct dentry *dentry)
1721 {
1722 	struct inode *inode = d_inode(dentry);
1723 
1724 	if (inode && S_ISREG(inode->i_mode))
1725 		nfsd_file_close_inode_sync(inode);
1726 }
1727 
1728 static bool
1729 nfsd_has_cached_files(struct dentry *dentry)
1730 {
1731 	bool		ret = false;
1732 	struct inode *inode = d_inode(dentry);
1733 
1734 	if (inode && S_ISREG(inode->i_mode))
1735 		ret = nfsd_file_is_cached(inode);
1736 	return ret;
1737 }
1738 
1739 /*
1740  * Rename a file
1741  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1742  */
1743 __be32
1744 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1745 			    struct svc_fh *tfhp, char *tname, int tlen)
1746 {
1747 	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1748 	struct inode	*fdir, *tdir;
1749 	__be32		err;
1750 	int		host_err;
1751 	bool		close_cached = false;
1752 
1753 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1754 	if (err)
1755 		goto out;
1756 	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1757 	if (err)
1758 		goto out;
1759 
1760 	fdentry = ffhp->fh_dentry;
1761 	fdir = d_inode(fdentry);
1762 
1763 	tdentry = tfhp->fh_dentry;
1764 	tdir = d_inode(tdentry);
1765 
1766 	err = nfserr_perm;
1767 	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1768 		goto out;
1769 
1770 retry:
1771 	host_err = fh_want_write(ffhp);
1772 	if (host_err) {
1773 		err = nfserrno(host_err);
1774 		goto out;
1775 	}
1776 
1777 	/* cannot use fh_lock as we need deadlock protective ordering
1778 	 * so do it by hand */
1779 	trap = lock_rename(tdentry, fdentry);
1780 	ffhp->fh_locked = tfhp->fh_locked = true;
1781 	fh_fill_pre_attrs(ffhp);
1782 	fh_fill_pre_attrs(tfhp);
1783 
1784 	odentry = lookup_one_len(fname, fdentry, flen);
1785 	host_err = PTR_ERR(odentry);
1786 	if (IS_ERR(odentry))
1787 		goto out_nfserr;
1788 
1789 	host_err = -ENOENT;
1790 	if (d_really_is_negative(odentry))
1791 		goto out_dput_old;
1792 	host_err = -EINVAL;
1793 	if (odentry == trap)
1794 		goto out_dput_old;
1795 
1796 	ndentry = lookup_one_len(tname, tdentry, tlen);
1797 	host_err = PTR_ERR(ndentry);
1798 	if (IS_ERR(ndentry))
1799 		goto out_dput_old;
1800 	host_err = -ENOTEMPTY;
1801 	if (ndentry == trap)
1802 		goto out_dput_new;
1803 
1804 	host_err = -EXDEV;
1805 	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1806 		goto out_dput_new;
1807 	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1808 		goto out_dput_new;
1809 
1810 	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1811 	    nfsd_has_cached_files(ndentry)) {
1812 		close_cached = true;
1813 		goto out_dput_old;
1814 	} else {
1815 		struct renamedata rd = {
1816 			.old_mnt_userns	= &init_user_ns,
1817 			.old_dir	= fdir,
1818 			.old_dentry	= odentry,
1819 			.new_mnt_userns	= &init_user_ns,
1820 			.new_dir	= tdir,
1821 			.new_dentry	= ndentry,
1822 		};
1823 		host_err = vfs_rename(&rd);
1824 		if (!host_err) {
1825 			host_err = commit_metadata(tfhp);
1826 			if (!host_err)
1827 				host_err = commit_metadata(ffhp);
1828 		}
1829 	}
1830  out_dput_new:
1831 	dput(ndentry);
1832  out_dput_old:
1833 	dput(odentry);
1834  out_nfserr:
1835 	err = nfserrno(host_err);
1836 	/*
1837 	 * We cannot rely on fh_unlock on the two filehandles,
1838 	 * as that would do the wrong thing if the two directories
1839 	 * were the same, so again we do it by hand.
1840 	 */
1841 	if (!close_cached) {
1842 		fh_fill_post_attrs(ffhp);
1843 		fh_fill_post_attrs(tfhp);
1844 	}
1845 	unlock_rename(tdentry, fdentry);
1846 	ffhp->fh_locked = tfhp->fh_locked = false;
1847 	fh_drop_write(ffhp);
1848 
1849 	/*
1850 	 * If the target dentry has cached open files, then we need to try to
1851 	 * close them prior to doing the rename. Flushing delayed fput
1852 	 * shouldn't be done with locks held however, so we delay it until this
1853 	 * point and then reattempt the whole shebang.
1854 	 */
1855 	if (close_cached) {
1856 		close_cached = false;
1857 		nfsd_close_cached_files(ndentry);
1858 		dput(ndentry);
1859 		goto retry;
1860 	}
1861 out:
1862 	return err;
1863 }
1864 
1865 /*
1866  * Unlink a file or directory
1867  * N.B. After this call fhp needs an fh_put
1868  */
1869 __be32
1870 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1871 				char *fname, int flen)
1872 {
1873 	struct dentry	*dentry, *rdentry;
1874 	struct inode	*dirp;
1875 	struct inode	*rinode;
1876 	__be32		err;
1877 	int		host_err;
1878 
1879 	err = nfserr_acces;
1880 	if (!flen || isdotent(fname, flen))
1881 		goto out;
1882 	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1883 	if (err)
1884 		goto out;
1885 
1886 	host_err = fh_want_write(fhp);
1887 	if (host_err)
1888 		goto out_nfserr;
1889 
1890 	fh_lock_nested(fhp, I_MUTEX_PARENT);
1891 	dentry = fhp->fh_dentry;
1892 	dirp = d_inode(dentry);
1893 
1894 	rdentry = lookup_one_len(fname, dentry, flen);
1895 	host_err = PTR_ERR(rdentry);
1896 	if (IS_ERR(rdentry))
1897 		goto out_drop_write;
1898 
1899 	if (d_really_is_negative(rdentry)) {
1900 		dput(rdentry);
1901 		host_err = -ENOENT;
1902 		goto out_drop_write;
1903 	}
1904 	rinode = d_inode(rdentry);
1905 	ihold(rinode);
1906 
1907 	if (!type)
1908 		type = d_inode(rdentry)->i_mode & S_IFMT;
1909 
1910 	if (type != S_IFDIR) {
1911 		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1912 			nfsd_close_cached_files(rdentry);
1913 		host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
1914 	} else {
1915 		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
1916 	}
1917 
1918 	fh_unlock(fhp);
1919 	if (!host_err)
1920 		host_err = commit_metadata(fhp);
1921 	dput(rdentry);
1922 	iput(rinode);    /* truncate the inode here */
1923 
1924 out_drop_write:
1925 	fh_drop_write(fhp);
1926 out_nfserr:
1927 	if (host_err == -EBUSY) {
1928 		/* name is mounted-on. There is no perfect
1929 		 * error status.
1930 		 */
1931 		if (nfsd_v4client(rqstp))
1932 			err = nfserr_file_open;
1933 		else
1934 			err = nfserr_acces;
1935 	} else {
1936 		err = nfserrno(host_err);
1937 	}
1938 out:
1939 	return err;
1940 }
1941 
1942 /*
1943  * We do this buffering because we must not call back into the file
1944  * system's ->lookup() method from the filldir callback. That may well
1945  * deadlock a number of file systems.
1946  *
1947  * This is based heavily on the implementation of same in XFS.
1948  */
1949 struct buffered_dirent {
1950 	u64		ino;
1951 	loff_t		offset;
1952 	int		namlen;
1953 	unsigned int	d_type;
1954 	char		name[];
1955 };
1956 
1957 struct readdir_data {
1958 	struct dir_context ctx;
1959 	char		*dirent;
1960 	size_t		used;
1961 	int		full;
1962 };
1963 
1964 static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1965 				 int namlen, loff_t offset, u64 ino,
1966 				 unsigned int d_type)
1967 {
1968 	struct readdir_data *buf =
1969 		container_of(ctx, struct readdir_data, ctx);
1970 	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1971 	unsigned int reclen;
1972 
1973 	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1974 	if (buf->used + reclen > PAGE_SIZE) {
1975 		buf->full = 1;
1976 		return -EINVAL;
1977 	}
1978 
1979 	de->namlen = namlen;
1980 	de->offset = offset;
1981 	de->ino = ino;
1982 	de->d_type = d_type;
1983 	memcpy(de->name, name, namlen);
1984 	buf->used += reclen;
1985 
1986 	return 0;
1987 }
1988 
1989 static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
1990 				    nfsd_filldir_t func, struct readdir_cd *cdp,
1991 				    loff_t *offsetp)
1992 {
1993 	struct buffered_dirent *de;
1994 	int host_err;
1995 	int size;
1996 	loff_t offset;
1997 	struct readdir_data buf = {
1998 		.ctx.actor = nfsd_buffered_filldir,
1999 		.dirent = (void *)__get_free_page(GFP_KERNEL)
2000 	};
2001 
2002 	if (!buf.dirent)
2003 		return nfserrno(-ENOMEM);
2004 
2005 	offset = *offsetp;
2006 
2007 	while (1) {
2008 		unsigned int reclen;
2009 
2010 		cdp->err = nfserr_eof; /* will be cleared on successful read */
2011 		buf.used = 0;
2012 		buf.full = 0;
2013 
2014 		host_err = iterate_dir(file, &buf.ctx);
2015 		if (buf.full)
2016 			host_err = 0;
2017 
2018 		if (host_err < 0)
2019 			break;
2020 
2021 		size = buf.used;
2022 
2023 		if (!size)
2024 			break;
2025 
2026 		de = (struct buffered_dirent *)buf.dirent;
2027 		while (size > 0) {
2028 			offset = de->offset;
2029 
2030 			if (func(cdp, de->name, de->namlen, de->offset,
2031 				 de->ino, de->d_type))
2032 				break;
2033 
2034 			if (cdp->err != nfs_ok)
2035 				break;
2036 
2037 			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
2038 
2039 			reclen = ALIGN(sizeof(*de) + de->namlen,
2040 				       sizeof(u64));
2041 			size -= reclen;
2042 			de = (struct buffered_dirent *)((char *)de + reclen);
2043 		}
2044 		if (size > 0) /* We bailed out early */
2045 			break;
2046 
2047 		offset = vfs_llseek(file, 0, SEEK_CUR);
2048 	}
2049 
2050 	free_page((unsigned long)(buf.dirent));
2051 
2052 	if (host_err)
2053 		return nfserrno(host_err);
2054 
2055 	*offsetp = offset;
2056 	return cdp->err;
2057 }
2058 
2059 /*
2060  * Read entries from a directory.
2061  * The  NFSv3/4 verifier we ignore for now.
2062  */
2063 __be32
2064 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2065 	     struct readdir_cd *cdp, nfsd_filldir_t func)
2066 {
2067 	__be32		err;
2068 	struct file	*file;
2069 	loff_t		offset = *offsetp;
2070 	int             may_flags = NFSD_MAY_READ;
2071 
2072 	/* NFSv2 only supports 32 bit cookies */
2073 	if (rqstp->rq_vers > 2)
2074 		may_flags |= NFSD_MAY_64BIT_COOKIE;
2075 
2076 	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2077 	if (err)
2078 		goto out;
2079 
2080 	offset = vfs_llseek(file, offset, SEEK_SET);
2081 	if (offset < 0) {
2082 		err = nfserrno((int)offset);
2083 		goto out_close;
2084 	}
2085 
2086 	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2087 
2088 	if (err == nfserr_eof || err == nfserr_toosmall)
2089 		err = nfs_ok; /* can still be found in ->err */
2090 out_close:
2091 	fput(file);
2092 out:
2093 	return err;
2094 }
2095 
2096 /*
2097  * Get file system stats
2098  * N.B. After this call fhp needs an fh_put
2099  */
2100 __be32
2101 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2102 {
2103 	__be32 err;
2104 
2105 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2106 	if (!err) {
2107 		struct path path = {
2108 			.mnt	= fhp->fh_export->ex_path.mnt,
2109 			.dentry	= fhp->fh_dentry,
2110 		};
2111 		if (vfs_statfs(&path, stat))
2112 			err = nfserr_io;
2113 	}
2114 	return err;
2115 }
2116 
2117 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2118 {
2119 	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2120 }
2121 
2122 #ifdef CONFIG_NFSD_V4
2123 /*
2124  * Helper function to translate error numbers. In the case of xattr operations,
2125  * some error codes need to be translated outside of the standard translations.
2126  *
2127  * ENODATA needs to be translated to nfserr_noxattr.
2128  * E2BIG to nfserr_xattr2big.
2129  *
2130  * Additionally, vfs_listxattr can return -ERANGE. This means that the
2131  * file has too many extended attributes to retrieve inside an
2132  * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2133  * filesystems will allow the adding of extended attributes until they hit
2134  * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2135  * So, at that point, the attributes are present and valid, but can't
2136  * be retrieved using listxattr, since the upper level xattr code enforces
2137  * the XATTR_LIST_MAX limit.
2138  *
2139  * This bug means that we need to deal with listxattr returning -ERANGE. The
2140  * best mapping is to return TOOSMALL.
2141  */
2142 static __be32
2143 nfsd_xattr_errno(int err)
2144 {
2145 	switch (err) {
2146 	case -ENODATA:
2147 		return nfserr_noxattr;
2148 	case -E2BIG:
2149 		return nfserr_xattr2big;
2150 	case -ERANGE:
2151 		return nfserr_toosmall;
2152 	}
2153 	return nfserrno(err);
2154 }
2155 
2156 /*
2157  * Retrieve the specified user extended attribute. To avoid always
2158  * having to allocate the maximum size (since we are not getting
2159  * a maximum size from the RPC), do a probe + alloc. Hold a reader
2160  * lock on i_rwsem to prevent the extended attribute from changing
2161  * size while we're doing this.
2162  */
2163 __be32
2164 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2165 	      void **bufp, int *lenp)
2166 {
2167 	ssize_t len;
2168 	__be32 err;
2169 	char *buf;
2170 	struct inode *inode;
2171 	struct dentry *dentry;
2172 
2173 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2174 	if (err)
2175 		return err;
2176 
2177 	err = nfs_ok;
2178 	dentry = fhp->fh_dentry;
2179 	inode = d_inode(dentry);
2180 
2181 	inode_lock_shared(inode);
2182 
2183 	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
2184 
2185 	/*
2186 	 * Zero-length attribute, just return.
2187 	 */
2188 	if (len == 0) {
2189 		*bufp = NULL;
2190 		*lenp = 0;
2191 		goto out;
2192 	}
2193 
2194 	if (len < 0) {
2195 		err = nfsd_xattr_errno(len);
2196 		goto out;
2197 	}
2198 
2199 	if (len > *lenp) {
2200 		err = nfserr_toosmall;
2201 		goto out;
2202 	}
2203 
2204 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2205 	if (buf == NULL) {
2206 		err = nfserr_jukebox;
2207 		goto out;
2208 	}
2209 
2210 	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
2211 	if (len <= 0) {
2212 		kvfree(buf);
2213 		buf = NULL;
2214 		err = nfsd_xattr_errno(len);
2215 	}
2216 
2217 	*lenp = len;
2218 	*bufp = buf;
2219 
2220 out:
2221 	inode_unlock_shared(inode);
2222 
2223 	return err;
2224 }
2225 
2226 /*
2227  * Retrieve the xattr names. Since we can't know how many are
2228  * user extended attributes, we must get all attributes here,
2229  * and have the XDR encode filter out the "user." ones.
2230  *
2231  * While this could always just allocate an XATTR_LIST_MAX
2232  * buffer, that's a waste, so do a probe + allocate. To
2233  * avoid any changes between the probe and allocate, wrap
2234  * this in inode_lock.
2235  */
2236 __be32
2237 nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2238 	       int *lenp)
2239 {
2240 	ssize_t len;
2241 	__be32 err;
2242 	char *buf;
2243 	struct inode *inode;
2244 	struct dentry *dentry;
2245 
2246 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2247 	if (err)
2248 		return err;
2249 
2250 	dentry = fhp->fh_dentry;
2251 	inode = d_inode(dentry);
2252 	*lenp = 0;
2253 
2254 	inode_lock_shared(inode);
2255 
2256 	len = vfs_listxattr(dentry, NULL, 0);
2257 	if (len <= 0) {
2258 		err = nfsd_xattr_errno(len);
2259 		goto out;
2260 	}
2261 
2262 	if (len > XATTR_LIST_MAX) {
2263 		err = nfserr_xattr2big;
2264 		goto out;
2265 	}
2266 
2267 	/*
2268 	 * We're holding i_rwsem - use GFP_NOFS.
2269 	 */
2270 	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2271 	if (buf == NULL) {
2272 		err = nfserr_jukebox;
2273 		goto out;
2274 	}
2275 
2276 	len = vfs_listxattr(dentry, buf, len);
2277 	if (len <= 0) {
2278 		kvfree(buf);
2279 		err = nfsd_xattr_errno(len);
2280 		goto out;
2281 	}
2282 
2283 	*lenp = len;
2284 	*bufp = buf;
2285 
2286 	err = nfs_ok;
2287 out:
2288 	inode_unlock_shared(inode);
2289 
2290 	return err;
2291 }
2292 
2293 /*
2294  * Removexattr and setxattr need to call fh_lock to both lock the inode
2295  * and set the change attribute. Since the top-level vfs_removexattr
2296  * and vfs_setxattr calls already do their own inode_lock calls, call
2297  * the _locked variant. Pass in a NULL pointer for delegated_inode,
2298  * and let the client deal with NFS4ERR_DELAY (same as with e.g.
2299  * setattr and remove).
2300  */
2301 __be32
2302 nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2303 {
2304 	__be32 err;
2305 	int ret;
2306 
2307 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2308 	if (err)
2309 		return err;
2310 
2311 	ret = fh_want_write(fhp);
2312 	if (ret)
2313 		return nfserrno(ret);
2314 
2315 	fh_lock(fhp);
2316 
2317 	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
2318 				       name, NULL);
2319 
2320 	fh_unlock(fhp);
2321 	fh_drop_write(fhp);
2322 
2323 	return nfsd_xattr_errno(ret);
2324 }
2325 
2326 __be32
2327 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2328 	      void *buf, u32 len, u32 flags)
2329 {
2330 	__be32 err;
2331 	int ret;
2332 
2333 	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2334 	if (err)
2335 		return err;
2336 
2337 	ret = fh_want_write(fhp);
2338 	if (ret)
2339 		return nfserrno(ret);
2340 	fh_lock(fhp);
2341 
2342 	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
2343 				    len, flags, NULL);
2344 
2345 	fh_unlock(fhp);
2346 	fh_drop_write(fhp);
2347 
2348 	return nfsd_xattr_errno(ret);
2349 }
2350 #endif
2351 
2352 /*
2353  * Check for a user's access permissions to this inode.
2354  */
2355 __be32
2356 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2357 					struct dentry *dentry, int acc)
2358 {
2359 	struct inode	*inode = d_inode(dentry);
2360 	int		err;
2361 
2362 	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2363 		return 0;
2364 #if 0
2365 	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2366 		acc,
2367 		(acc & NFSD_MAY_READ)?	" read"  : "",
2368 		(acc & NFSD_MAY_WRITE)?	" write" : "",
2369 		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2370 		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2371 		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2372 		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2373 		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2374 		inode->i_mode,
2375 		IS_IMMUTABLE(inode)?	" immut" : "",
2376 		IS_APPEND(inode)?	" append" : "",
2377 		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2378 	dprintk("      owner %d/%d user %d/%d\n",
2379 		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2380 #endif
2381 
2382 	/* Normally we reject any write/sattr etc access on a read-only file
2383 	 * system.  But if it is IRIX doing check on write-access for a
2384 	 * device special file, we ignore rofs.
2385 	 */
2386 	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2387 		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2388 			if (exp_rdonly(rqstp, exp) ||
2389 			    __mnt_is_readonly(exp->ex_path.mnt))
2390 				return nfserr_rofs;
2391 			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2392 				return nfserr_perm;
2393 		}
2394 	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2395 		return nfserr_perm;
2396 
2397 	if (acc & NFSD_MAY_LOCK) {
2398 		/* If we cannot rely on authentication in NLM requests,
2399 		 * just allow locks, otherwise require read permission, or
2400 		 * ownership
2401 		 */
2402 		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2403 			return 0;
2404 		else
2405 			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2406 	}
2407 	/*
2408 	 * The file owner always gets access permission for accesses that
2409 	 * would normally be checked at open time. This is to make
2410 	 * file access work even when the client has done a fchmod(fd, 0).
2411 	 *
2412 	 * However, `cp foo bar' should fail nevertheless when bar is
2413 	 * readonly. A sensible way to do this might be to reject all
2414 	 * attempts to truncate a read-only file, because a creat() call
2415 	 * always implies file truncation.
2416 	 * ... but this isn't really fair.  A process may reasonably call
2417 	 * ftruncate on an open file descriptor on a file with perm 000.
2418 	 * We must trust the client to do permission checking - using "ACCESS"
2419 	 * with NFSv3.
2420 	 */
2421 	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2422 	    uid_eq(inode->i_uid, current_fsuid()))
2423 		return 0;
2424 
2425 	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2426 	err = inode_permission(&init_user_ns, inode,
2427 			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2428 
2429 	/* Allow read access to binaries even when mode 111 */
2430 	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2431 	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2432 	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2433 		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
2434 
2435 	return err? nfserrno(err) : 0;
2436 }
2437