vfs.c revision ea49dc79
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 */
58int
59nfsd_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);
109out:
110	return err;
111}
112
113static 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
124static 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 */
155int 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
173nfsd_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
232out_nfserr:
233	exp_put(exp);
234	return nfserrno(host_err);
235}
236
237/*
238 * Look up one component of a pathname.
239 * N.B. After this call _both_ fhp and resfh need an fh_put
240 *
241 * If the lookup would cross a mountpoint, and the mounted filesystem
242 * is exported to the client with NFSEXP_NOHIDE, then the lookup is
243 * accepted as it stands and the mounted directory is
244 * returned. Otherwise the covered directory is returned.
245 * NOTE: this mountpoint crossing is not supported properly by all
246 *   clients and is explicitly disallowed for NFSv3
247 */
248__be32
249nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
250				unsigned int len, struct svc_fh *resfh)
251{
252	struct svc_export	*exp;
253	struct dentry		*dentry;
254	__be32 err;
255
256	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
257	if (err)
258		return err;
259	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
260	if (err)
261		return err;
262	err = check_nfsd_access(exp, rqstp);
263	if (err)
264		goto out;
265	/*
266	 * Note: we compose the file handle now, but as the
267	 * dentry may be negative, it may need to be updated.
268	 */
269	err = fh_compose(resfh, exp, dentry, fhp);
270	if (!err && d_really_is_negative(dentry))
271		err = nfserr_noent;
272out:
273	dput(dentry);
274	exp_put(exp);
275	return err;
276}
277
278/*
279 * Commit metadata changes to stable storage.
280 */
281static int
282commit_inode_metadata(struct inode *inode)
283{
284	const struct export_operations *export_ops = inode->i_sb->s_export_op;
285
286	if (export_ops->commit_metadata)
287		return export_ops->commit_metadata(inode);
288	return sync_inode_metadata(inode, 1);
289}
290
291static int
292commit_metadata(struct svc_fh *fhp)
293{
294	struct inode *inode = d_inode(fhp->fh_dentry);
295
296	if (!EX_ISSYNC(fhp->fh_export))
297		return 0;
298	return commit_inode_metadata(inode);
299}
300
301/*
302 * Go over the attributes and take care of the small differences between
303 * NFS semantics and what Linux expects.
304 */
305static void
306nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
307{
308	/* sanitize the mode change */
309	if (iap->ia_valid & ATTR_MODE) {
310		iap->ia_mode &= S_IALLUGO;
311		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
312	}
313
314	/* Revoke setuid/setgid on chown */
315	if (!S_ISDIR(inode->i_mode) &&
316	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
317		iap->ia_valid |= ATTR_KILL_PRIV;
318		if (iap->ia_valid & ATTR_MODE) {
319			/* we're setting mode too, just clear the s*id bits */
320			iap->ia_mode &= ~S_ISUID;
321			if (iap->ia_mode & S_IXGRP)
322				iap->ia_mode &= ~S_ISGID;
323		} else {
324			/* set ATTR_KILL_* bits and let VFS handle it */
325			iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
326		}
327	}
328}
329
330static __be32
331nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
332		struct iattr *iap)
333{
334	struct inode *inode = d_inode(fhp->fh_dentry);
335	int host_err;
336
337	if (iap->ia_size < inode->i_size) {
338		__be32 err;
339
340		err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
341				NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
342		if (err)
343			return err;
344	}
345
346	host_err = get_write_access(inode);
347	if (host_err)
348		goto out_nfserrno;
349
350	host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
351	if (host_err)
352		goto out_put_write_access;
353	return 0;
354
355out_put_write_access:
356	put_write_access(inode);
357out_nfserrno:
358	return nfserrno(host_err);
359}
360
361/*
362 * Set various file attributes.  After this call fhp needs an fh_put.
363 */
364__be32
365nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
366	     int check_guard, time64_t guardtime)
367{
368	struct dentry	*dentry;
369	struct inode	*inode;
370	int		accmode = NFSD_MAY_SATTR;
371	umode_t		ftype = 0;
372	__be32		err;
373	int		host_err;
374	bool		get_write_count;
375	bool		size_change = (iap->ia_valid & ATTR_SIZE);
376
377	if (iap->ia_valid & ATTR_SIZE) {
378		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
379		ftype = S_IFREG;
380	}
381
382	/*
383	 * If utimes(2) and friends are called with times not NULL, we should
384	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
385	 * will return EACCES, when the caller's effective UID does not match
386	 * the owner of the file, and the caller is not privileged. In this
387	 * situation, we should return EPERM(notify_change will return this).
388	 */
389	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
390		accmode |= NFSD_MAY_OWNER_OVERRIDE;
391		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
392			accmode |= NFSD_MAY_WRITE;
393	}
394
395	/* Callers that do fh_verify should do the fh_want_write: */
396	get_write_count = !fhp->fh_dentry;
397
398	/* Get inode */
399	err = fh_verify(rqstp, fhp, ftype, accmode);
400	if (err)
401		return err;
402	if (get_write_count) {
403		host_err = fh_want_write(fhp);
404		if (host_err)
405			goto out;
406	}
407
408	dentry = fhp->fh_dentry;
409	inode = d_inode(dentry);
410
411	/* Ignore any mode updates on symlinks */
412	if (S_ISLNK(inode->i_mode))
413		iap->ia_valid &= ~ATTR_MODE;
414
415	if (!iap->ia_valid)
416		return 0;
417
418	nfsd_sanitize_attrs(inode, iap);
419
420	if (check_guard && guardtime != inode->i_ctime.tv_sec)
421		return nfserr_notsync;
422
423	/*
424	 * The size case is special, it changes the file in addition to the
425	 * attributes, and file systems don't expect it to be mixed with
426	 * "random" attribute changes.  We thus split out the size change
427	 * into a separate call to ->setattr, and do the rest as a separate
428	 * setattr call.
429	 */
430	if (size_change) {
431		err = nfsd_get_write_access(rqstp, fhp, iap);
432		if (err)
433			return err;
434	}
435
436	fh_lock(fhp);
437	if (size_change) {
438		/*
439		 * RFC5661, Section 18.30.4:
440		 *   Changing the size of a file with SETATTR indirectly
441		 *   changes the time_modify and change attributes.
442		 *
443		 * (and similar for the older RFCs)
444		 */
445		struct iattr size_attr = {
446			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
447			.ia_size	= iap->ia_size,
448		};
449
450		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
451		if (host_err)
452			goto out_unlock;
453		iap->ia_valid &= ~ATTR_SIZE;
454
455		/*
456		 * Avoid the additional setattr call below if the only other
457		 * attribute that the client sends is the mtime, as we update
458		 * it as part of the size change above.
459		 */
460		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
461			goto out_unlock;
462	}
463
464	iap->ia_valid |= ATTR_CTIME;
465	host_err = notify_change(&init_user_ns, dentry, iap, NULL);
466
467out_unlock:
468	fh_unlock(fhp);
469	if (size_change)
470		put_write_access(inode);
471out:
472	if (!host_err)
473		host_err = commit_metadata(fhp);
474	return nfserrno(host_err);
475}
476
477#if defined(CONFIG_NFSD_V4)
478/*
479 * NFS junction information is stored in an extended attribute.
480 */
481#define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
482
483/**
484 * nfsd4_is_junction - Test if an object could be an NFS junction
485 *
486 * @dentry: object to test
487 *
488 * Returns 1 if "dentry" appears to contain NFS junction information.
489 * Otherwise 0 is returned.
490 */
491int nfsd4_is_junction(struct dentry *dentry)
492{
493	struct inode *inode = d_inode(dentry);
494
495	if (inode == NULL)
496		return 0;
497	if (inode->i_mode & S_IXUGO)
498		return 0;
499	if (!(inode->i_mode & S_ISVTX))
500		return 0;
501	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
502			 NULL, 0) <= 0)
503		return 0;
504	return 1;
505}
506#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
507__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
508		struct xdr_netobj *label)
509{
510	__be32 error;
511	int host_error;
512	struct dentry *dentry;
513
514	error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
515	if (error)
516		return error;
517
518	dentry = fhp->fh_dentry;
519
520	inode_lock(d_inode(dentry));
521	host_error = security_inode_setsecctx(dentry, label->data, label->len);
522	inode_unlock(d_inode(dentry));
523	return nfserrno(host_error);
524}
525#else
526__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
527		struct xdr_netobj *label)
528{
529	return nfserr_notsupp;
530}
531#endif
532
533__be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos,
534		struct nfsd_file *nf_dst, u64 dst_pos, u64 count, bool sync)
535{
536	struct file *src = nf_src->nf_file;
537	struct file *dst = nf_dst->nf_file;
538	loff_t cloned;
539	__be32 ret = 0;
540
541	down_write(&nf_dst->nf_rwsem);
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 = commit_inode_metadata(file_inode(src));
557		if (status < 0) {
558			nfsd_reset_boot_verifier(net_generic(nf_dst->nf_net,
559						 nfsd_net_id));
560			ret = nfserrno(status);
561		}
562	}
563out_err:
564	up_write(&nf_dst->nf_rwsem);
565	return ret;
566}
567
568ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
569			     u64 dst_pos, u64 count)
570{
571
572	/*
573	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
574	 * thread and client rpc slot.  The choice of 4MB is somewhat
575	 * arbitrary.  We might instead base this on r/wsize, or make it
576	 * tunable, or use a time instead of a byte limit, or implement
577	 * asynchronous copy.  In theory a client could also recognize a
578	 * limit like this and pipeline multiple COPY requests.
579	 */
580	count = min_t(u64, count, 1 << 22);
581	return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
582}
583
584__be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
585			   struct file *file, loff_t offset, loff_t len,
586			   int flags)
587{
588	int error;
589
590	if (!S_ISREG(file_inode(file)->i_mode))
591		return nfserr_inval;
592
593	error = vfs_fallocate(file, flags, offset, len);
594	if (!error)
595		error = commit_metadata(fhp);
596
597	return nfserrno(error);
598}
599#endif /* defined(CONFIG_NFSD_V4) */
600
601#ifdef CONFIG_NFSD_V3
602/*
603 * Check server access rights to a file system object
604 */
605struct accessmap {
606	u32		access;
607	int		how;
608};
609static struct accessmap	nfs3_regaccess[] = {
610    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
611    {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
612    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
613    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
614
615#ifdef CONFIG_NFSD_V4
616    {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
617    {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
618    {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
619#endif
620
621    {	0,			0				}
622};
623
624static struct accessmap	nfs3_diraccess[] = {
625    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
626    {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
627    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
628    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
629    {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
630
631#ifdef CONFIG_NFSD_V4
632    {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
633    {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
634    {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
635#endif
636
637    {	0,			0				}
638};
639
640static struct accessmap	nfs3_anyaccess[] = {
641	/* Some clients - Solaris 2.6 at least, make an access call
642	 * to the server to check for access for things like /dev/null
643	 * (which really, the server doesn't care about).  So
644	 * We provide simple access checking for them, looking
645	 * mainly at mode bits, and we make sure to ignore read-only
646	 * filesystem checks
647	 */
648    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
649    {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
650    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
651    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
652
653    {	0,			0				}
654};
655
656__be32
657nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
658{
659	struct accessmap	*map;
660	struct svc_export	*export;
661	struct dentry		*dentry;
662	u32			query, result = 0, sresult = 0;
663	__be32			error;
664
665	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
666	if (error)
667		goto out;
668
669	export = fhp->fh_export;
670	dentry = fhp->fh_dentry;
671
672	if (d_is_reg(dentry))
673		map = nfs3_regaccess;
674	else if (d_is_dir(dentry))
675		map = nfs3_diraccess;
676	else
677		map = nfs3_anyaccess;
678
679
680	query = *access;
681	for  (; map->access; map++) {
682		if (map->access & query) {
683			__be32 err2;
684
685			sresult |= map->access;
686
687			err2 = nfsd_permission(rqstp, export, dentry, map->how);
688			switch (err2) {
689			case nfs_ok:
690				result |= map->access;
691				break;
692
693			/* the following error codes just mean the access was not allowed,
694			 * rather than an error occurred */
695			case nfserr_rofs:
696			case nfserr_acces:
697			case nfserr_perm:
698				/* simply don't "or" in the access bit. */
699				break;
700			default:
701				error = err2;
702				goto out;
703			}
704		}
705	}
706	*access = result;
707	if (supported)
708		*supported = sresult;
709
710 out:
711	return error;
712}
713#endif /* CONFIG_NFSD_V3 */
714
715int nfsd_open_break_lease(struct inode *inode, int access)
716{
717	unsigned int mode;
718
719	if (access & NFSD_MAY_NOT_BREAK_LEASE)
720		return 0;
721	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
722	return break_lease(inode, mode | O_NONBLOCK);
723}
724
725/*
726 * Open an existing file or directory.
727 * The may_flags argument indicates the type of open (read/write/lock)
728 * and additional flags.
729 * N.B. After this call fhp needs an fh_put
730 */
731static __be32
732__nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
733			int may_flags, struct file **filp)
734{
735	struct path	path;
736	struct inode	*inode;
737	struct file	*file;
738	int		flags = O_RDONLY|O_LARGEFILE;
739	__be32		err;
740	int		host_err = 0;
741
742	path.mnt = fhp->fh_export->ex_path.mnt;
743	path.dentry = fhp->fh_dentry;
744	inode = d_inode(path.dentry);
745
746	/* Disallow write access to files with the append-only bit set
747	 * or any access when mandatory locking enabled
748	 */
749	err = nfserr_perm;
750	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
751		goto out;
752	/*
753	 * We must ignore files (but only files) which might have mandatory
754	 * locks on them because there is no way to know if the accesser has
755	 * the lock.
756	 */
757	if (S_ISREG((inode)->i_mode) && mandatory_lock(inode))
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;
792out_nfserr:
793	err = nfserrno(host_err);
794out:
795	return err;
796}
797
798__be32
799nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
800		int may_flags, struct file **filp)
801{
802	__be32 err;
803
804	validate_process_creds();
805	/*
806	 * If we get here, then the client has already done an "open",
807	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
808	 * in case a chmod has now revoked permission.
809	 *
810	 * Arguably we should also allow the owner override for
811	 * directories, but we never have and it doesn't seem to have
812	 * caused anyone a problem.  If we were to change this, note
813	 * also that our filldir callbacks would need a variant of
814	 * lookup_one_len that doesn't check permissions.
815	 */
816	if (type == S_IFREG)
817		may_flags |= NFSD_MAY_OWNER_OVERRIDE;
818	err = fh_verify(rqstp, fhp, type, may_flags);
819	if (!err)
820		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
821	validate_process_creds();
822	return err;
823}
824
825__be32
826nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
827		int may_flags, struct file **filp)
828{
829	__be32 err;
830
831	validate_process_creds();
832	err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
833	validate_process_creds();
834	return err;
835}
836
837/*
838 * Grab and keep cached pages associated with a file in the svc_rqst
839 * so that they can be passed to the network sendmsg/sendpage routines
840 * directly. They will be released after the sending has completed.
841 */
842static int
843nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
844		  struct splice_desc *sd)
845{
846	struct svc_rqst *rqstp = sd->u.data;
847	struct page **pp = rqstp->rq_next_page;
848	struct page *page = buf->page;
849
850	if (rqstp->rq_res.page_len == 0) {
851		svc_rqst_replace_page(rqstp, page);
852		rqstp->rq_res.page_base = buf->offset;
853	} else if (page != pp[-1]) {
854		svc_rqst_replace_page(rqstp, page);
855	}
856	rqstp->rq_res.page_len += sd->len;
857
858	return sd->len;
859}
860
861static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
862				    struct splice_desc *sd)
863{
864	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
865}
866
867static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
868		size_t expected)
869{
870	if (expected != 0 && len == 0)
871		return 1;
872	if (offset+len >= i_size_read(file_inode(file)))
873		return 1;
874	return 0;
875}
876
877static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
878			       struct file *file, loff_t offset,
879			       unsigned long *count, u32 *eof, ssize_t host_err)
880{
881	if (host_err >= 0) {
882		nfsd_stats_io_read_add(fhp->fh_export, host_err);
883		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
884		*count = host_err;
885		fsnotify_access(file);
886		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
887		return 0;
888	} else {
889		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
890		return nfserrno(host_err);
891	}
892}
893
894__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
895			struct file *file, loff_t offset, unsigned long *count,
896			u32 *eof)
897{
898	struct splice_desc sd = {
899		.len		= 0,
900		.total_len	= *count,
901		.pos		= offset,
902		.u.data		= rqstp,
903	};
904	ssize_t host_err;
905
906	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
907	rqstp->rq_next_page = rqstp->rq_respages + 1;
908	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
909	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
910}
911
912__be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
913		  struct file *file, loff_t offset,
914		  struct kvec *vec, int vlen, unsigned long *count,
915		  u32 *eof)
916{
917	struct iov_iter iter;
918	loff_t ppos = offset;
919	ssize_t host_err;
920
921	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
922	iov_iter_kvec(&iter, READ, vec, vlen, *count);
923	host_err = vfs_iter_read(file, &iter, &ppos, 0);
924	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
925}
926
927/*
928 * Gathered writes: If another process is currently writing to the file,
929 * there's a high chance this is another nfsd (triggered by a bulk write
930 * from a client's biod). Rather than syncing the file with each write
931 * request, we sleep for 10 msec.
932 *
933 * I don't know if this roughly approximates C. Juszak's idea of
934 * gathered writes, but it's a nice and simple solution (IMHO), and it
935 * seems to work:-)
936 *
937 * Note: we do this only in the NFSv2 case, since v3 and higher have a
938 * better tool (separate unstable writes and commits) for solving this
939 * problem.
940 */
941static int wait_for_concurrent_writes(struct file *file)
942{
943	struct inode *inode = file_inode(file);
944	static ino_t last_ino;
945	static dev_t last_dev;
946	int err = 0;
947
948	if (atomic_read(&inode->i_writecount) > 1
949	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
950		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
951		msleep(10);
952		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
953	}
954
955	if (inode->i_state & I_DIRTY) {
956		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
957		err = vfs_fsync(file, 0);
958	}
959	last_ino = inode->i_ino;
960	last_dev = inode->i_sb->s_dev;
961	return err;
962}
963
964__be32
965nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
966				loff_t offset, struct kvec *vec, int vlen,
967				unsigned long *cnt, int stable,
968				__be32 *verf)
969{
970	struct file		*file = nf->nf_file;
971	struct super_block	*sb = file_inode(file)->i_sb;
972	struct svc_export	*exp;
973	struct iov_iter		iter;
974	__be32			nfserr;
975	int			host_err;
976	int			use_wgather;
977	loff_t			pos = offset;
978	unsigned long		exp_op_flags = 0;
979	unsigned int		pflags = current->flags;
980	rwf_t			flags = 0;
981	bool			restore_flags = false;
982
983	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
984
985	if (sb->s_export_op)
986		exp_op_flags = sb->s_export_op->flags;
987
988	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
989	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
990		/*
991		 * We want throttling in balance_dirty_pages()
992		 * and shrink_inactive_list() to only consider
993		 * the backingdev we are writing to, so that nfs to
994		 * localhost doesn't cause nfsd to lock up due to all
995		 * the client's dirty pages or its congested queue.
996		 */
997		current->flags |= PF_LOCAL_THROTTLE;
998		restore_flags = true;
999	}
1000
1001	exp = fhp->fh_export;
1002	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1003
1004	if (!EX_ISSYNC(exp))
1005		stable = NFS_UNSTABLE;
1006
1007	if (stable && !use_wgather)
1008		flags |= RWF_SYNC;
1009
1010	iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
1011	if (flags & RWF_SYNC) {
1012		down_write(&nf->nf_rwsem);
1013		host_err = vfs_iter_write(file, &iter, &pos, flags);
1014		if (host_err < 0)
1015			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1016						 nfsd_net_id));
1017		up_write(&nf->nf_rwsem);
1018	} else {
1019		down_read(&nf->nf_rwsem);
1020		if (verf)
1021			nfsd_copy_boot_verifier(verf,
1022					net_generic(SVC_NET(rqstp),
1023					nfsd_net_id));
1024		host_err = vfs_iter_write(file, &iter, &pos, flags);
1025		up_read(&nf->nf_rwsem);
1026	}
1027	if (host_err < 0) {
1028		nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1029					 nfsd_net_id));
1030		goto out_nfserr;
1031	}
1032	*cnt = host_err;
1033	nfsd_stats_io_write_add(exp, *cnt);
1034	fsnotify_modify(file);
1035
1036	if (stable && use_wgather) {
1037		host_err = wait_for_concurrent_writes(file);
1038		if (host_err < 0)
1039			nfsd_reset_boot_verifier(net_generic(SVC_NET(rqstp),
1040						 nfsd_net_id));
1041	}
1042
1043out_nfserr:
1044	if (host_err >= 0) {
1045		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1046		nfserr = nfs_ok;
1047	} else {
1048		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1049		nfserr = nfserrno(host_err);
1050	}
1051	if (restore_flags)
1052		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1053	return nfserr;
1054}
1055
1056/*
1057 * Read data from a file. count must contain the requested read count
1058 * on entry. On return, *count contains the number of bytes actually read.
1059 * N.B. After this call fhp needs an fh_put
1060 */
1061__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1062	loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
1063	u32 *eof)
1064{
1065	struct nfsd_file	*nf;
1066	struct file *file;
1067	__be32 err;
1068
1069	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1070	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
1071	if (err)
1072		return err;
1073
1074	file = nf->nf_file;
1075	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1076		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1077	else
1078		err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
1079
1080	nfsd_file_put(nf);
1081
1082	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1083
1084	return err;
1085}
1086
1087/*
1088 * Write data to a file.
1089 * The stable flag requests synchronous writes.
1090 * N.B. After this call fhp needs an fh_put
1091 */
1092__be32
1093nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1094	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1095	   __be32 *verf)
1096{
1097	struct nfsd_file *nf;
1098	__be32 err;
1099
1100	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1101
1102	err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1103	if (err)
1104		goto out;
1105
1106	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1107			vlen, cnt, stable, verf);
1108	nfsd_file_put(nf);
1109out:
1110	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1111	return err;
1112}
1113
1114#ifdef CONFIG_NFSD_V3
1115static int
1116nfsd_filemap_write_and_wait_range(struct nfsd_file *nf, loff_t offset,
1117				  loff_t end)
1118{
1119	struct address_space *mapping = nf->nf_file->f_mapping;
1120	int ret = filemap_fdatawrite_range(mapping, offset, end);
1121
1122	if (ret)
1123		return ret;
1124	filemap_fdatawait_range_keep_errors(mapping, offset, end);
1125	return 0;
1126}
1127
1128/*
1129 * Commit all pending writes to stable storage.
1130 *
1131 * Note: we only guarantee that data that lies within the range specified
1132 * by the 'offset' and 'count' parameters will be synced.
1133 *
1134 * Unfortunately we cannot lock the file to make sure we return full WCC
1135 * data to the client, as locking happens lower down in the filesystem.
1136 */
1137__be32
1138nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
1139               loff_t offset, unsigned long count, __be32 *verf)
1140{
1141	struct nfsd_file	*nf;
1142	loff_t			end = LLONG_MAX;
1143	__be32			err = nfserr_inval;
1144
1145	if (offset < 0)
1146		goto out;
1147	if (count != 0) {
1148		end = offset + (loff_t)count - 1;
1149		if (end < offset)
1150			goto out;
1151	}
1152
1153	err = nfsd_file_acquire(rqstp, fhp,
1154			NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
1155	if (err)
1156		goto out;
1157	if (EX_ISSYNC(fhp->fh_export)) {
1158		int err2 = nfsd_filemap_write_and_wait_range(nf, offset, end);
1159
1160		down_write(&nf->nf_rwsem);
1161		if (!err2)
1162			err2 = vfs_fsync_range(nf->nf_file, offset, end, 0);
1163		switch (err2) {
1164		case 0:
1165			nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1166						nfsd_net_id));
1167			break;
1168		case -EINVAL:
1169			err = nfserr_notsupp;
1170			break;
1171		default:
1172			err = nfserrno(err2);
1173			nfsd_reset_boot_verifier(net_generic(nf->nf_net,
1174						 nfsd_net_id));
1175		}
1176		up_write(&nf->nf_rwsem);
1177	} else
1178		nfsd_copy_boot_verifier(verf, net_generic(nf->nf_net,
1179					nfsd_net_id));
1180
1181	nfsd_file_put(nf);
1182out:
1183	return err;
1184}
1185#endif /* CONFIG_NFSD_V3 */
1186
1187static __be32
1188nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *resfhp,
1189			struct iattr *iap)
1190{
1191	/*
1192	 * Mode has already been set earlier in create:
1193	 */
1194	iap->ia_valid &= ~ATTR_MODE;
1195	/*
1196	 * Setting uid/gid works only for root.  Irix appears to
1197	 * send along the gid on create when it tries to implement
1198	 * setgid directories via NFS:
1199	 */
1200	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1201		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1202	if (iap->ia_valid)
1203		return nfsd_setattr(rqstp, resfhp, iap, 0, (time64_t)0);
1204	/* Callers expect file metadata to be committed here */
1205	return nfserrno(commit_metadata(resfhp));
1206}
1207
1208/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1209 * setting size to 0 may fail for some specific file systems by the permission
1210 * checking which requires WRITE permission but the mode is 000.
1211 * we ignore the resizing(to 0) on the just new created file, since the size is
1212 * 0 after file created.
1213 *
1214 * call this only after vfs_create() is called.
1215 * */
1216static void
1217nfsd_check_ignore_resizing(struct iattr *iap)
1218{
1219	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1220		iap->ia_valid &= ~ATTR_SIZE;
1221}
1222
1223/* The parent directory should already be locked: */
1224__be32
1225nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1226		char *fname, int flen, struct iattr *iap,
1227		int type, dev_t rdev, struct svc_fh *resfhp)
1228{
1229	struct dentry	*dentry, *dchild;
1230	struct inode	*dirp;
1231	__be32		err;
1232	__be32		err2;
1233	int		host_err;
1234
1235	dentry = fhp->fh_dentry;
1236	dirp = d_inode(dentry);
1237
1238	dchild = dget(resfhp->fh_dentry);
1239	if (!fhp->fh_locked) {
1240		WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
1241				dentry);
1242		err = nfserr_io;
1243		goto out;
1244	}
1245
1246	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1247	if (err)
1248		goto out;
1249
1250	if (!(iap->ia_valid & ATTR_MODE))
1251		iap->ia_mode = 0;
1252	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1253
1254	if (!IS_POSIXACL(dirp))
1255		iap->ia_mode &= ~current_umask();
1256
1257	err = 0;
1258	host_err = 0;
1259	switch (type) {
1260	case S_IFREG:
1261		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1262		if (!host_err)
1263			nfsd_check_ignore_resizing(iap);
1264		break;
1265	case S_IFDIR:
1266		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
1267		if (!host_err && unlikely(d_unhashed(dchild))) {
1268			struct dentry *d;
1269			d = lookup_one_len(dchild->d_name.name,
1270					   dchild->d_parent,
1271					   dchild->d_name.len);
1272			if (IS_ERR(d)) {
1273				host_err = PTR_ERR(d);
1274				break;
1275			}
1276			if (unlikely(d_is_negative(d))) {
1277				dput(d);
1278				err = nfserr_serverfault;
1279				goto out;
1280			}
1281			dput(resfhp->fh_dentry);
1282			resfhp->fh_dentry = dget(d);
1283			err = fh_update(resfhp);
1284			dput(dchild);
1285			dchild = d;
1286			if (err)
1287				goto out;
1288		}
1289		break;
1290	case S_IFCHR:
1291	case S_IFBLK:
1292	case S_IFIFO:
1293	case S_IFSOCK:
1294		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
1295				     iap->ia_mode, rdev);
1296		break;
1297	default:
1298		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1299		       type);
1300		host_err = -EINVAL;
1301	}
1302	if (host_err < 0)
1303		goto out_nfserr;
1304
1305	err = nfsd_create_setattr(rqstp, resfhp, iap);
1306
1307	/*
1308	 * nfsd_create_setattr already committed the child.  Transactional
1309	 * filesystems had a chance to commit changes for both parent and
1310	 * child simultaneously making the following commit_metadata a
1311	 * noop.
1312	 */
1313	err2 = nfserrno(commit_metadata(fhp));
1314	if (err2)
1315		err = err2;
1316	/*
1317	 * Update the file handle to get the new inode info.
1318	 */
1319	if (!err)
1320		err = fh_update(resfhp);
1321out:
1322	dput(dchild);
1323	return err;
1324
1325out_nfserr:
1326	err = nfserrno(host_err);
1327	goto out;
1328}
1329
1330/*
1331 * Create a filesystem object (regular, directory, special).
1332 * Note that the parent directory is left locked.
1333 *
1334 * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1335 */
1336__be32
1337nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1338		char *fname, int flen, struct iattr *iap,
1339		int type, dev_t rdev, struct svc_fh *resfhp)
1340{
1341	struct dentry	*dentry, *dchild = NULL;
1342	__be32		err;
1343	int		host_err;
1344
1345	if (isdotent(fname, flen))
1346		return nfserr_exist;
1347
1348	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1349	if (err)
1350		return err;
1351
1352	dentry = fhp->fh_dentry;
1353
1354	host_err = fh_want_write(fhp);
1355	if (host_err)
1356		return nfserrno(host_err);
1357
1358	fh_lock_nested(fhp, I_MUTEX_PARENT);
1359	dchild = lookup_one_len(fname, dentry, flen);
1360	host_err = PTR_ERR(dchild);
1361	if (IS_ERR(dchild))
1362		return nfserrno(host_err);
1363	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1364	/*
1365	 * We unconditionally drop our ref to dchild as fh_compose will have
1366	 * already grabbed its own ref for it.
1367	 */
1368	dput(dchild);
1369	if (err)
1370		return err;
1371	return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
1372					rdev, resfhp);
1373}
1374
1375#ifdef CONFIG_NFSD_V3
1376
1377/*
1378 * NFSv3 and NFSv4 version of nfsd_create
1379 */
1380__be32
1381do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1382		char *fname, int flen, struct iattr *iap,
1383		struct svc_fh *resfhp, int createmode, u32 *verifier,
1384	        bool *truncp, bool *created)
1385{
1386	struct dentry	*dentry, *dchild = NULL;
1387	struct inode	*dirp;
1388	__be32		err;
1389	int		host_err;
1390	__u32		v_mtime=0, v_atime=0;
1391
1392	err = nfserr_perm;
1393	if (!flen)
1394		goto out;
1395	err = nfserr_exist;
1396	if (isdotent(fname, flen))
1397		goto out;
1398	if (!(iap->ia_valid & ATTR_MODE))
1399		iap->ia_mode = 0;
1400	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
1401	if (err)
1402		goto out;
1403
1404	dentry = fhp->fh_dentry;
1405	dirp = d_inode(dentry);
1406
1407	host_err = fh_want_write(fhp);
1408	if (host_err)
1409		goto out_nfserr;
1410
1411	fh_lock_nested(fhp, I_MUTEX_PARENT);
1412
1413	/*
1414	 * Compose the response file handle.
1415	 */
1416	dchild = lookup_one_len(fname, dentry, flen);
1417	host_err = PTR_ERR(dchild);
1418	if (IS_ERR(dchild))
1419		goto out_nfserr;
1420
1421	/* If file doesn't exist, check for permissions to create one */
1422	if (d_really_is_negative(dchild)) {
1423		err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1424		if (err)
1425			goto out;
1426	}
1427
1428	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1429	if (err)
1430		goto out;
1431
1432	if (nfsd_create_is_exclusive(createmode)) {
1433		/* solaris7 gets confused (bugid 4218508) if these have
1434		 * the high bit set, so just clear the high bits. If this is
1435		 * ever changed to use different attrs for storing the
1436		 * verifier, then do_open_lookup() will also need to be fixed
1437		 * accordingly.
1438		 */
1439		v_mtime = verifier[0]&0x7fffffff;
1440		v_atime = verifier[1]&0x7fffffff;
1441	}
1442
1443	if (d_really_is_positive(dchild)) {
1444		err = 0;
1445
1446		switch (createmode) {
1447		case NFS3_CREATE_UNCHECKED:
1448			if (! d_is_reg(dchild))
1449				goto out;
1450			else if (truncp) {
1451				/* in nfsv4, we need to treat this case a little
1452				 * differently.  we don't want to truncate the
1453				 * file now; this would be wrong if the OPEN
1454				 * fails for some other reason.  furthermore,
1455				 * if the size is nonzero, we should ignore it
1456				 * according to spec!
1457				 */
1458				*truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
1459			}
1460			else {
1461				iap->ia_valid &= ATTR_SIZE;
1462				goto set_attr;
1463			}
1464			break;
1465		case NFS3_CREATE_EXCLUSIVE:
1466			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1467			    && d_inode(dchild)->i_atime.tv_sec == v_atime
1468			    && d_inode(dchild)->i_size  == 0 ) {
1469				if (created)
1470					*created = true;
1471				break;
1472			}
1473			fallthrough;
1474		case NFS4_CREATE_EXCLUSIVE4_1:
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				goto set_attr;
1481			}
1482			fallthrough;
1483		case NFS3_CREATE_GUARDED:
1484			err = nfserr_exist;
1485		}
1486		fh_drop_write(fhp);
1487		goto out;
1488	}
1489
1490	if (!IS_POSIXACL(dirp))
1491		iap->ia_mode &= ~current_umask();
1492
1493	host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1494	if (host_err < 0) {
1495		fh_drop_write(fhp);
1496		goto out_nfserr;
1497	}
1498	if (created)
1499		*created = true;
1500
1501	nfsd_check_ignore_resizing(iap);
1502
1503	if (nfsd_create_is_exclusive(createmode)) {
1504		/* Cram the verifier into atime/mtime */
1505		iap->ia_valid = ATTR_MTIME|ATTR_ATIME
1506			| ATTR_MTIME_SET|ATTR_ATIME_SET;
1507		/* XXX someone who knows this better please fix it for nsec */
1508		iap->ia_mtime.tv_sec = v_mtime;
1509		iap->ia_atime.tv_sec = v_atime;
1510		iap->ia_mtime.tv_nsec = 0;
1511		iap->ia_atime.tv_nsec = 0;
1512	}
1513
1514 set_attr:
1515	err = nfsd_create_setattr(rqstp, resfhp, iap);
1516
1517	/*
1518	 * nfsd_create_setattr already committed the child
1519	 * (and possibly also the parent).
1520	 */
1521	if (!err)
1522		err = nfserrno(commit_metadata(fhp));
1523
1524	/*
1525	 * Update the filehandle to get the new inode info.
1526	 */
1527	if (!err)
1528		err = fh_update(resfhp);
1529
1530 out:
1531	fh_unlock(fhp);
1532	if (dchild && !IS_ERR(dchild))
1533		dput(dchild);
1534	fh_drop_write(fhp);
1535 	return err;
1536
1537 out_nfserr:
1538	err = nfserrno(host_err);
1539	goto out;
1540}
1541#endif /* CONFIG_NFSD_V3 */
1542
1543/*
1544 * Read a symlink. On entry, *lenp must contain the maximum path length that
1545 * fits into the buffer. On return, it contains the true length.
1546 * N.B. After this call fhp needs an fh_put
1547 */
1548__be32
1549nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1550{
1551	__be32		err;
1552	const char *link;
1553	struct path path;
1554	DEFINE_DELAYED_CALL(done);
1555	int len;
1556
1557	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1558	if (unlikely(err))
1559		return err;
1560
1561	path.mnt = fhp->fh_export->ex_path.mnt;
1562	path.dentry = fhp->fh_dentry;
1563
1564	if (unlikely(!d_is_symlink(path.dentry)))
1565		return nfserr_inval;
1566
1567	touch_atime(&path);
1568
1569	link = vfs_get_link(path.dentry, &done);
1570	if (IS_ERR(link))
1571		return nfserrno(PTR_ERR(link));
1572
1573	len = strlen(link);
1574	if (len < *lenp)
1575		*lenp = len;
1576	memcpy(buf, link, *lenp);
1577	do_delayed_call(&done);
1578	return 0;
1579}
1580
1581/*
1582 * Create a symlink and look up its inode
1583 * N.B. After this call _both_ fhp and resfhp need an fh_put
1584 */
1585__be32
1586nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1587				char *fname, int flen,
1588				char *path,
1589				struct svc_fh *resfhp)
1590{
1591	struct dentry	*dentry, *dnew;
1592	__be32		err, cerr;
1593	int		host_err;
1594
1595	err = nfserr_noent;
1596	if (!flen || path[0] == '\0')
1597		goto out;
1598	err = nfserr_exist;
1599	if (isdotent(fname, flen))
1600		goto out;
1601
1602	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1603	if (err)
1604		goto out;
1605
1606	host_err = fh_want_write(fhp);
1607	if (host_err)
1608		goto out_nfserr;
1609
1610	fh_lock(fhp);
1611	dentry = fhp->fh_dentry;
1612	dnew = lookup_one_len(fname, dentry, flen);
1613	host_err = PTR_ERR(dnew);
1614	if (IS_ERR(dnew))
1615		goto out_nfserr;
1616
1617	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
1618	err = nfserrno(host_err);
1619	fh_unlock(fhp);
1620	if (!err)
1621		err = nfserrno(commit_metadata(fhp));
1622
1623	fh_drop_write(fhp);
1624
1625	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1626	dput(dnew);
1627	if (err==0) err = cerr;
1628out:
1629	return err;
1630
1631out_nfserr:
1632	err = nfserrno(host_err);
1633	goto out;
1634}
1635
1636/*
1637 * Create a hardlink
1638 * N.B. After this call _both_ ffhp and tfhp need an fh_put
1639 */
1640__be32
1641nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1642				char *name, int len, struct svc_fh *tfhp)
1643{
1644	struct dentry	*ddir, *dnew, *dold;
1645	struct inode	*dirp;
1646	__be32		err;
1647	int		host_err;
1648
1649	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1650	if (err)
1651		goto out;
1652	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1653	if (err)
1654		goto out;
1655	err = nfserr_isdir;
1656	if (d_is_dir(tfhp->fh_dentry))
1657		goto out;
1658	err = nfserr_perm;
1659	if (!len)
1660		goto out;
1661	err = nfserr_exist;
1662	if (isdotent(name, len))
1663		goto out;
1664
1665	host_err = fh_want_write(tfhp);
1666	if (host_err) {
1667		err = nfserrno(host_err);
1668		goto out;
1669	}
1670
1671	fh_lock_nested(ffhp, I_MUTEX_PARENT);
1672	ddir = ffhp->fh_dentry;
1673	dirp = d_inode(ddir);
1674
1675	dnew = lookup_one_len(name, ddir, len);
1676	host_err = PTR_ERR(dnew);
1677	if (IS_ERR(dnew))
1678		goto out_nfserr;
1679
1680	dold = tfhp->fh_dentry;
1681
1682	err = nfserr_noent;
1683	if (d_really_is_negative(dold))
1684		goto out_dput;
1685	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
1686	fh_unlock(ffhp);
1687	if (!host_err) {
1688		err = nfserrno(commit_metadata(ffhp));
1689		if (!err)
1690			err = nfserrno(commit_metadata(tfhp));
1691	} else {
1692		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1693			err = nfserr_acces;
1694		else
1695			err = nfserrno(host_err);
1696	}
1697out_dput:
1698	dput(dnew);
1699out_unlock:
1700	fh_unlock(ffhp);
1701	fh_drop_write(tfhp);
1702out:
1703	return err;
1704
1705out_nfserr:
1706	err = nfserrno(host_err);
1707	goto out_unlock;
1708}
1709
1710static void
1711nfsd_close_cached_files(struct dentry *dentry)
1712{
1713	struct inode *inode = d_inode(dentry);
1714
1715	if (inode && S_ISREG(inode->i_mode))
1716		nfsd_file_close_inode_sync(inode);
1717}
1718
1719static bool
1720nfsd_has_cached_files(struct dentry *dentry)
1721{
1722	bool		ret = false;
1723	struct inode *inode = d_inode(dentry);
1724
1725	if (inode && S_ISREG(inode->i_mode))
1726		ret = nfsd_file_is_cached(inode);
1727	return ret;
1728}
1729
1730/*
1731 * Rename a file
1732 * N.B. After this call _both_ ffhp and tfhp need an fh_put
1733 */
1734__be32
1735nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1736			    struct svc_fh *tfhp, char *tname, int tlen)
1737{
1738	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1739	struct inode	*fdir, *tdir;
1740	__be32		err;
1741	int		host_err;
1742	bool		close_cached = false;
1743
1744	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1745	if (err)
1746		goto out;
1747	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1748	if (err)
1749		goto out;
1750
1751	fdentry = ffhp->fh_dentry;
1752	fdir = d_inode(fdentry);
1753
1754	tdentry = tfhp->fh_dentry;
1755	tdir = d_inode(tdentry);
1756
1757	err = nfserr_perm;
1758	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1759		goto out;
1760
1761retry:
1762	host_err = fh_want_write(ffhp);
1763	if (host_err) {
1764		err = nfserrno(host_err);
1765		goto out;
1766	}
1767
1768	/* cannot use fh_lock as we need deadlock protective ordering
1769	 * so do it by hand */
1770	trap = lock_rename(tdentry, fdentry);
1771	ffhp->fh_locked = tfhp->fh_locked = true;
1772	fill_pre_wcc(ffhp);
1773	fill_pre_wcc(tfhp);
1774
1775	odentry = lookup_one_len(fname, fdentry, flen);
1776	host_err = PTR_ERR(odentry);
1777	if (IS_ERR(odentry))
1778		goto out_nfserr;
1779
1780	host_err = -ENOENT;
1781	if (d_really_is_negative(odentry))
1782		goto out_dput_old;
1783	host_err = -EINVAL;
1784	if (odentry == trap)
1785		goto out_dput_old;
1786
1787	ndentry = lookup_one_len(tname, tdentry, tlen);
1788	host_err = PTR_ERR(ndentry);
1789	if (IS_ERR(ndentry))
1790		goto out_dput_old;
1791	host_err = -ENOTEMPTY;
1792	if (ndentry == trap)
1793		goto out_dput_new;
1794
1795	host_err = -EXDEV;
1796	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1797		goto out_dput_new;
1798	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1799		goto out_dput_new;
1800
1801	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1802	    nfsd_has_cached_files(ndentry)) {
1803		close_cached = true;
1804		goto out_dput_old;
1805	} else {
1806		struct renamedata rd = {
1807			.old_mnt_userns	= &init_user_ns,
1808			.old_dir	= fdir,
1809			.old_dentry	= odentry,
1810			.new_mnt_userns	= &init_user_ns,
1811			.new_dir	= tdir,
1812			.new_dentry	= ndentry,
1813		};
1814		host_err = vfs_rename(&rd);
1815		if (!host_err) {
1816			host_err = commit_metadata(tfhp);
1817			if (!host_err)
1818				host_err = commit_metadata(ffhp);
1819		}
1820	}
1821 out_dput_new:
1822	dput(ndentry);
1823 out_dput_old:
1824	dput(odentry);
1825 out_nfserr:
1826	err = nfserrno(host_err);
1827	/*
1828	 * We cannot rely on fh_unlock on the two filehandles,
1829	 * as that would do the wrong thing if the two directories
1830	 * were the same, so again we do it by hand.
1831	 */
1832	if (!close_cached) {
1833		fill_post_wcc(ffhp);
1834		fill_post_wcc(tfhp);
1835	}
1836	unlock_rename(tdentry, fdentry);
1837	ffhp->fh_locked = tfhp->fh_locked = false;
1838	fh_drop_write(ffhp);
1839
1840	/*
1841	 * If the target dentry has cached open files, then we need to try to
1842	 * close them prior to doing the rename. Flushing delayed fput
1843	 * shouldn't be done with locks held however, so we delay it until this
1844	 * point and then reattempt the whole shebang.
1845	 */
1846	if (close_cached) {
1847		close_cached = false;
1848		nfsd_close_cached_files(ndentry);
1849		dput(ndentry);
1850		goto retry;
1851	}
1852out:
1853	return err;
1854}
1855
1856/*
1857 * Unlink a file or directory
1858 * N.B. After this call fhp needs an fh_put
1859 */
1860__be32
1861nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1862				char *fname, int flen)
1863{
1864	struct dentry	*dentry, *rdentry;
1865	struct inode	*dirp;
1866	struct inode	*rinode;
1867	__be32		err;
1868	int		host_err;
1869
1870	err = nfserr_acces;
1871	if (!flen || isdotent(fname, flen))
1872		goto out;
1873	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1874	if (err)
1875		goto out;
1876
1877	host_err = fh_want_write(fhp);
1878	if (host_err)
1879		goto out_nfserr;
1880
1881	fh_lock_nested(fhp, I_MUTEX_PARENT);
1882	dentry = fhp->fh_dentry;
1883	dirp = d_inode(dentry);
1884
1885	rdentry = lookup_one_len(fname, dentry, flen);
1886	host_err = PTR_ERR(rdentry);
1887	if (IS_ERR(rdentry))
1888		goto out_drop_write;
1889
1890	if (d_really_is_negative(rdentry)) {
1891		dput(rdentry);
1892		host_err = -ENOENT;
1893		goto out_drop_write;
1894	}
1895	rinode = d_inode(rdentry);
1896	ihold(rinode);
1897
1898	if (!type)
1899		type = d_inode(rdentry)->i_mode & S_IFMT;
1900
1901	if (type != S_IFDIR) {
1902		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1903			nfsd_close_cached_files(rdentry);
1904		host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
1905	} else {
1906		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
1907	}
1908
1909	fh_unlock(fhp);
1910	if (!host_err)
1911		host_err = commit_metadata(fhp);
1912	dput(rdentry);
1913	iput(rinode);    /* truncate the inode here */
1914
1915out_drop_write:
1916	fh_drop_write(fhp);
1917out_nfserr:
1918	if (host_err == -EBUSY) {
1919		/* name is mounted-on. There is no perfect
1920		 * error status.
1921		 */
1922		if (nfsd_v4client(rqstp))
1923			err = nfserr_file_open;
1924		else
1925			err = nfserr_acces;
1926	} else {
1927		err = nfserrno(host_err);
1928	}
1929out:
1930	return err;
1931}
1932
1933/*
1934 * We do this buffering because we must not call back into the file
1935 * system's ->lookup() method from the filldir callback. That may well
1936 * deadlock a number of file systems.
1937 *
1938 * This is based heavily on the implementation of same in XFS.
1939 */
1940struct buffered_dirent {
1941	u64		ino;
1942	loff_t		offset;
1943	int		namlen;
1944	unsigned int	d_type;
1945	char		name[];
1946};
1947
1948struct readdir_data {
1949	struct dir_context ctx;
1950	char		*dirent;
1951	size_t		used;
1952	int		full;
1953};
1954
1955static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1956				 int namlen, loff_t offset, u64 ino,
1957				 unsigned int d_type)
1958{
1959	struct readdir_data *buf =
1960		container_of(ctx, struct readdir_data, ctx);
1961	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1962	unsigned int reclen;
1963
1964	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1965	if (buf->used + reclen > PAGE_SIZE) {
1966		buf->full = 1;
1967		return -EINVAL;
1968	}
1969
1970	de->namlen = namlen;
1971	de->offset = offset;
1972	de->ino = ino;
1973	de->d_type = d_type;
1974	memcpy(de->name, name, namlen);
1975	buf->used += reclen;
1976
1977	return 0;
1978}
1979
1980static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
1981				    nfsd_filldir_t func, struct readdir_cd *cdp,
1982				    loff_t *offsetp)
1983{
1984	struct buffered_dirent *de;
1985	int host_err;
1986	int size;
1987	loff_t offset;
1988	struct readdir_data buf = {
1989		.ctx.actor = nfsd_buffered_filldir,
1990		.dirent = (void *)__get_free_page(GFP_KERNEL)
1991	};
1992
1993	if (!buf.dirent)
1994		return nfserrno(-ENOMEM);
1995
1996	offset = *offsetp;
1997
1998	while (1) {
1999		unsigned int reclen;
2000
2001		cdp->err = nfserr_eof; /* will be cleared on successful read */
2002		buf.used = 0;
2003		buf.full = 0;
2004
2005		host_err = iterate_dir(file, &buf.ctx);
2006		if (buf.full)
2007			host_err = 0;
2008
2009		if (host_err < 0)
2010			break;
2011
2012		size = buf.used;
2013
2014		if (!size)
2015			break;
2016
2017		de = (struct buffered_dirent *)buf.dirent;
2018		while (size > 0) {
2019			offset = de->offset;
2020
2021			if (func(cdp, de->name, de->namlen, de->offset,
2022				 de->ino, de->d_type))
2023				break;
2024
2025			if (cdp->err != nfs_ok)
2026				break;
2027
2028			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
2029
2030			reclen = ALIGN(sizeof(*de) + de->namlen,
2031				       sizeof(u64));
2032			size -= reclen;
2033			de = (struct buffered_dirent *)((char *)de + reclen);
2034		}
2035		if (size > 0) /* We bailed out early */
2036			break;
2037
2038		offset = vfs_llseek(file, 0, SEEK_CUR);
2039	}
2040
2041	free_page((unsigned long)(buf.dirent));
2042
2043	if (host_err)
2044		return nfserrno(host_err);
2045
2046	*offsetp = offset;
2047	return cdp->err;
2048}
2049
2050/*
2051 * Read entries from a directory.
2052 * The  NFSv3/4 verifier we ignore for now.
2053 */
2054__be32
2055nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2056	     struct readdir_cd *cdp, nfsd_filldir_t func)
2057{
2058	__be32		err;
2059	struct file	*file;
2060	loff_t		offset = *offsetp;
2061	int             may_flags = NFSD_MAY_READ;
2062
2063	/* NFSv2 only supports 32 bit cookies */
2064	if (rqstp->rq_vers > 2)
2065		may_flags |= NFSD_MAY_64BIT_COOKIE;
2066
2067	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2068	if (err)
2069		goto out;
2070
2071	offset = vfs_llseek(file, offset, SEEK_SET);
2072	if (offset < 0) {
2073		err = nfserrno((int)offset);
2074		goto out_close;
2075	}
2076
2077	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2078
2079	if (err == nfserr_eof || err == nfserr_toosmall)
2080		err = nfs_ok; /* can still be found in ->err */
2081out_close:
2082	fput(file);
2083out:
2084	return err;
2085}
2086
2087/*
2088 * Get file system stats
2089 * N.B. After this call fhp needs an fh_put
2090 */
2091__be32
2092nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2093{
2094	__be32 err;
2095
2096	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2097	if (!err) {
2098		struct path path = {
2099			.mnt	= fhp->fh_export->ex_path.mnt,
2100			.dentry	= fhp->fh_dentry,
2101		};
2102		if (vfs_statfs(&path, stat))
2103			err = nfserr_io;
2104	}
2105	return err;
2106}
2107
2108static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2109{
2110	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2111}
2112
2113#ifdef CONFIG_NFSD_V4
2114/*
2115 * Helper function to translate error numbers. In the case of xattr operations,
2116 * some error codes need to be translated outside of the standard translations.
2117 *
2118 * ENODATA needs to be translated to nfserr_noxattr.
2119 * E2BIG to nfserr_xattr2big.
2120 *
2121 * Additionally, vfs_listxattr can return -ERANGE. This means that the
2122 * file has too many extended attributes to retrieve inside an
2123 * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2124 * filesystems will allow the adding of extended attributes until they hit
2125 * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2126 * So, at that point, the attributes are present and valid, but can't
2127 * be retrieved using listxattr, since the upper level xattr code enforces
2128 * the XATTR_LIST_MAX limit.
2129 *
2130 * This bug means that we need to deal with listxattr returning -ERANGE. The
2131 * best mapping is to return TOOSMALL.
2132 */
2133static __be32
2134nfsd_xattr_errno(int err)
2135{
2136	switch (err) {
2137	case -ENODATA:
2138		return nfserr_noxattr;
2139	case -E2BIG:
2140		return nfserr_xattr2big;
2141	case -ERANGE:
2142		return nfserr_toosmall;
2143	}
2144	return nfserrno(err);
2145}
2146
2147/*
2148 * Retrieve the specified user extended attribute. To avoid always
2149 * having to allocate the maximum size (since we are not getting
2150 * a maximum size from the RPC), do a probe + alloc. Hold a reader
2151 * lock on i_rwsem to prevent the extended attribute from changing
2152 * size while we're doing this.
2153 */
2154__be32
2155nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2156	      void **bufp, int *lenp)
2157{
2158	ssize_t len;
2159	__be32 err;
2160	char *buf;
2161	struct inode *inode;
2162	struct dentry *dentry;
2163
2164	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2165	if (err)
2166		return err;
2167
2168	err = nfs_ok;
2169	dentry = fhp->fh_dentry;
2170	inode = d_inode(dentry);
2171
2172	inode_lock_shared(inode);
2173
2174	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
2175
2176	/*
2177	 * Zero-length attribute, just return.
2178	 */
2179	if (len == 0) {
2180		*bufp = NULL;
2181		*lenp = 0;
2182		goto out;
2183	}
2184
2185	if (len < 0) {
2186		err = nfsd_xattr_errno(len);
2187		goto out;
2188	}
2189
2190	if (len > *lenp) {
2191		err = nfserr_toosmall;
2192		goto out;
2193	}
2194
2195	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2196	if (buf == NULL) {
2197		err = nfserr_jukebox;
2198		goto out;
2199	}
2200
2201	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
2202	if (len <= 0) {
2203		kvfree(buf);
2204		buf = NULL;
2205		err = nfsd_xattr_errno(len);
2206	}
2207
2208	*lenp = len;
2209	*bufp = buf;
2210
2211out:
2212	inode_unlock_shared(inode);
2213
2214	return err;
2215}
2216
2217/*
2218 * Retrieve the xattr names. Since we can't know how many are
2219 * user extended attributes, we must get all attributes here,
2220 * and have the XDR encode filter out the "user." ones.
2221 *
2222 * While this could always just allocate an XATTR_LIST_MAX
2223 * buffer, that's a waste, so do a probe + allocate. To
2224 * avoid any changes between the probe and allocate, wrap
2225 * this in inode_lock.
2226 */
2227__be32
2228nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2229	       int *lenp)
2230{
2231	ssize_t len;
2232	__be32 err;
2233	char *buf;
2234	struct inode *inode;
2235	struct dentry *dentry;
2236
2237	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2238	if (err)
2239		return err;
2240
2241	dentry = fhp->fh_dentry;
2242	inode = d_inode(dentry);
2243	*lenp = 0;
2244
2245	inode_lock_shared(inode);
2246
2247	len = vfs_listxattr(dentry, NULL, 0);
2248	if (len <= 0) {
2249		err = nfsd_xattr_errno(len);
2250		goto out;
2251	}
2252
2253	if (len > XATTR_LIST_MAX) {
2254		err = nfserr_xattr2big;
2255		goto out;
2256	}
2257
2258	/*
2259	 * We're holding i_rwsem - use GFP_NOFS.
2260	 */
2261	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2262	if (buf == NULL) {
2263		err = nfserr_jukebox;
2264		goto out;
2265	}
2266
2267	len = vfs_listxattr(dentry, buf, len);
2268	if (len <= 0) {
2269		kvfree(buf);
2270		err = nfsd_xattr_errno(len);
2271		goto out;
2272	}
2273
2274	*lenp = len;
2275	*bufp = buf;
2276
2277	err = nfs_ok;
2278out:
2279	inode_unlock_shared(inode);
2280
2281	return err;
2282}
2283
2284/*
2285 * Removexattr and setxattr need to call fh_lock to both lock the inode
2286 * and set the change attribute. Since the top-level vfs_removexattr
2287 * and vfs_setxattr calls already do their own inode_lock calls, call
2288 * the _locked variant. Pass in a NULL pointer for delegated_inode,
2289 * and let the client deal with NFS4ERR_DELAY (same as with e.g.
2290 * setattr and remove).
2291 */
2292__be32
2293nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2294{
2295	__be32 err;
2296	int ret;
2297
2298	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2299	if (err)
2300		return err;
2301
2302	ret = fh_want_write(fhp);
2303	if (ret)
2304		return nfserrno(ret);
2305
2306	fh_lock(fhp);
2307
2308	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
2309				       name, NULL);
2310
2311	fh_unlock(fhp);
2312	fh_drop_write(fhp);
2313
2314	return nfsd_xattr_errno(ret);
2315}
2316
2317__be32
2318nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2319	      void *buf, u32 len, u32 flags)
2320{
2321	__be32 err;
2322	int ret;
2323
2324	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2325	if (err)
2326		return err;
2327
2328	ret = fh_want_write(fhp);
2329	if (ret)
2330		return nfserrno(ret);
2331	fh_lock(fhp);
2332
2333	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
2334				    len, flags, NULL);
2335
2336	fh_unlock(fhp);
2337	fh_drop_write(fhp);
2338
2339	return nfsd_xattr_errno(ret);
2340}
2341#endif
2342
2343/*
2344 * Check for a user's access permissions to this inode.
2345 */
2346__be32
2347nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2348					struct dentry *dentry, int acc)
2349{
2350	struct inode	*inode = d_inode(dentry);
2351	int		err;
2352
2353	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2354		return 0;
2355#if 0
2356	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2357		acc,
2358		(acc & NFSD_MAY_READ)?	" read"  : "",
2359		(acc & NFSD_MAY_WRITE)?	" write" : "",
2360		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2361		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2362		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2363		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2364		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2365		inode->i_mode,
2366		IS_IMMUTABLE(inode)?	" immut" : "",
2367		IS_APPEND(inode)?	" append" : "",
2368		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2369	dprintk("      owner %d/%d user %d/%d\n",
2370		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2371#endif
2372
2373	/* Normally we reject any write/sattr etc access on a read-only file
2374	 * system.  But if it is IRIX doing check on write-access for a
2375	 * device special file, we ignore rofs.
2376	 */
2377	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2378		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2379			if (exp_rdonly(rqstp, exp) ||
2380			    __mnt_is_readonly(exp->ex_path.mnt))
2381				return nfserr_rofs;
2382			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2383				return nfserr_perm;
2384		}
2385	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2386		return nfserr_perm;
2387
2388	if (acc & NFSD_MAY_LOCK) {
2389		/* If we cannot rely on authentication in NLM requests,
2390		 * just allow locks, otherwise require read permission, or
2391		 * ownership
2392		 */
2393		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2394			return 0;
2395		else
2396			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2397	}
2398	/*
2399	 * The file owner always gets access permission for accesses that
2400	 * would normally be checked at open time. This is to make
2401	 * file access work even when the client has done a fchmod(fd, 0).
2402	 *
2403	 * However, `cp foo bar' should fail nevertheless when bar is
2404	 * readonly. A sensible way to do this might be to reject all
2405	 * attempts to truncate a read-only file, because a creat() call
2406	 * always implies file truncation.
2407	 * ... but this isn't really fair.  A process may reasonably call
2408	 * ftruncate on an open file descriptor on a file with perm 000.
2409	 * We must trust the client to do permission checking - using "ACCESS"
2410	 * with NFSv3.
2411	 */
2412	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2413	    uid_eq(inode->i_uid, current_fsuid()))
2414		return 0;
2415
2416	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2417	err = inode_permission(&init_user_ns, inode,
2418			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2419
2420	/* Allow read access to binaries even when mode 111 */
2421	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2422	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2423	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2424		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
2425
2426	return err? nfserrno(err) : 0;
2427}
2428