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