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/pagemap.h>
  30#include <linux/slab.h>
  31#include <linux/uaccess.h>
  32#include <linux/exportfs.h>
  33#include <linux/writeback.h>
  34#include <linux/security.h>
  35
  36#include "xdr3.h"
  37
  38#ifdef CONFIG_NFSD_V4
  39#include "../internal.h"
  40#include "acl.h"
  41#include "idmap.h"
  42#include "xdr4.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 * nfserrno - Map Linux errnos to NFS errnos
  54 * @errno: POSIX(-ish) error code to be mapped
  55 *
  56 * Returns the appropriate (net-endian) nfserr_* (or nfs_ok if errno is 0). If
  57 * it's an error we don't expect, log it once and return nfserr_io.
  58 */
  59__be32
  60nfserrno (int errno)
  61{
  62	static struct {
  63		__be32	nfserr;
  64		int	syserr;
  65	} nfs_errtbl[] = {
  66		{ nfs_ok, 0 },
  67		{ nfserr_perm, -EPERM },
  68		{ nfserr_noent, -ENOENT },
  69		{ nfserr_io, -EIO },
  70		{ nfserr_nxio, -ENXIO },
  71		{ nfserr_fbig, -E2BIG },
  72		{ nfserr_stale, -EBADF },
  73		{ nfserr_acces, -EACCES },
  74		{ nfserr_exist, -EEXIST },
  75		{ nfserr_xdev, -EXDEV },
  76		{ nfserr_mlink, -EMLINK },
  77		{ nfserr_nodev, -ENODEV },
  78		{ nfserr_notdir, -ENOTDIR },
  79		{ nfserr_isdir, -EISDIR },
  80		{ nfserr_inval, -EINVAL },
  81		{ nfserr_fbig, -EFBIG },
  82		{ nfserr_nospc, -ENOSPC },
  83		{ nfserr_rofs, -EROFS },
  84		{ nfserr_mlink, -EMLINK },
  85		{ nfserr_nametoolong, -ENAMETOOLONG },
  86		{ nfserr_notempty, -ENOTEMPTY },
  87		{ nfserr_dquot, -EDQUOT },
  88		{ nfserr_stale, -ESTALE },
  89		{ nfserr_jukebox, -ETIMEDOUT },
  90		{ nfserr_jukebox, -ERESTARTSYS },
  91		{ nfserr_jukebox, -EAGAIN },
  92		{ nfserr_jukebox, -EWOULDBLOCK },
  93		{ nfserr_jukebox, -ENOMEM },
  94		{ nfserr_io, -ETXTBSY },
  95		{ nfserr_notsupp, -EOPNOTSUPP },
  96		{ nfserr_toosmall, -ETOOSMALL },
  97		{ nfserr_serverfault, -ESERVERFAULT },
  98		{ nfserr_serverfault, -ENFILE },
  99		{ nfserr_io, -EREMOTEIO },
 100		{ nfserr_stale, -EOPENSTALE },
 101		{ nfserr_io, -EUCLEAN },
 102		{ nfserr_perm, -ENOKEY },
 103		{ nfserr_no_grace, -ENOGRACE},
 104	};
 105	int	i;
 106
 107	for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
 108		if (nfs_errtbl[i].syserr == errno)
 109			return nfs_errtbl[i].nfserr;
 110	}
 111	WARN_ONCE(1, "nfsd: non-standard errno: %d\n", errno);
 112	return nfserr_io;
 113}
 114
 115/* 
 116 * Called from nfsd_lookup and encode_dirent. Check if we have crossed 
 117 * a mount point.
 118 * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
 119 *  or nfs_ok having possibly changed *dpp and *expp
 120 */
 121int
 122nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, 
 123		        struct svc_export **expp)
 124{
 125	struct svc_export *exp = *expp, *exp2 = NULL;
 126	struct dentry *dentry = *dpp;
 127	struct path path = {.mnt = mntget(exp->ex_path.mnt),
 128			    .dentry = dget(dentry)};
 129	int err = 0;
 130
 131	err = follow_down(&path);
 132	if (err < 0)
 133		goto out;
 134	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
 135	    nfsd_mountpoint(dentry, exp) == 2) {
 136		/* This is only a mountpoint in some other namespace */
 137		path_put(&path);
 138		goto out;
 139	}
 140
 141	exp2 = rqst_exp_get_by_name(rqstp, &path);
 142	if (IS_ERR(exp2)) {
 143		err = PTR_ERR(exp2);
 144		/*
 145		 * We normally allow NFS clients to continue
 146		 * "underneath" a mountpoint that is not exported.
 147		 * The exception is V4ROOT, where no traversal is ever
 148		 * allowed without an explicit export of the new
 149		 * directory.
 150		 */
 151		if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
 152			err = 0;
 153		path_put(&path);
 154		goto out;
 155	}
 156	if (nfsd_v4client(rqstp) ||
 157		(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
 158		/* successfully crossed mount point */
 159		/*
 160		 * This is subtle: path.dentry is *not* on path.mnt
 161		 * at this point.  The only reason we are safe is that
 162		 * original mnt is pinned down by exp, so we should
 163		 * put path *before* putting exp
 164		 */
 165		*dpp = path.dentry;
 166		path.dentry = dentry;
 167		*expp = exp2;
 168		exp2 = exp;
 169	}
 170	path_put(&path);
 171	exp_put(exp2);
 172out:
 173	return err;
 174}
 175
 176static void follow_to_parent(struct path *path)
 177{
 178	struct dentry *dp;
 179
 180	while (path->dentry == path->mnt->mnt_root && follow_up(path))
 181		;
 182	dp = dget_parent(path->dentry);
 183	dput(path->dentry);
 184	path->dentry = dp;
 185}
 186
 187static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
 188{
 189	struct svc_export *exp2;
 190	struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
 191			    .dentry = dget(dparent)};
 192
 193	follow_to_parent(&path);
 194
 195	exp2 = rqst_exp_parent(rqstp, &path);
 196	if (PTR_ERR(exp2) == -ENOENT) {
 197		*dentryp = dget(dparent);
 198	} else if (IS_ERR(exp2)) {
 199		path_put(&path);
 200		return PTR_ERR(exp2);
 201	} else {
 202		*dentryp = dget(path.dentry);
 203		exp_put(*exp);
 204		*exp = exp2;
 205	}
 206	path_put(&path);
 207	return 0;
 208}
 209
 210/*
 211 * For nfsd purposes, we treat V4ROOT exports as though there was an
 212 * export at *every* directory.
 213 * We return:
 214 * '1' if this dentry *must* be an export point,
 215 * '2' if it might be, if there is really a mount here, and
 216 * '0' if there is no chance of an export point here.
 217 */
 218int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
 219{
 220	if (!d_inode(dentry))
 221		return 0;
 222	if (exp->ex_flags & NFSEXP_V4ROOT)
 223		return 1;
 224	if (nfsd4_is_junction(dentry))
 225		return 1;
 226	if (d_mountpoint(dentry))
 227		/*
 228		 * Might only be a mountpoint in a different namespace,
 229		 * but we need to check.
 230		 */
 231		return 2;
 232	return 0;
 233}
 234
 235__be32
 236nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
 237		   const char *name, unsigned int len,
 238		   struct svc_export **exp_ret, struct dentry **dentry_ret)
 239{
 240	struct svc_export	*exp;
 241	struct dentry		*dparent;
 242	struct dentry		*dentry;
 243	int			host_err;
 244
 245	dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
 246
 247	dparent = fhp->fh_dentry;
 248	exp = exp_get(fhp->fh_export);
 249
 250	/* Lookup the name, but don't follow links */
 251	if (isdotent(name, len)) {
 252		if (len==1)
 253			dentry = dget(dparent);
 254		else if (dparent != exp->ex_path.dentry)
 255			dentry = dget_parent(dparent);
 256		else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
 257			dentry = dget(dparent); /* .. == . just like at / */
 258		else {
 259			/* checking mountpoint crossing is very different when stepping up */
 260			host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
 261			if (host_err)
 262				goto out_nfserr;
 263		}
 264	} else {
 265		dentry = lookup_one_len_unlocked(name, dparent, len);
 266		host_err = PTR_ERR(dentry);
 267		if (IS_ERR(dentry))
 268			goto out_nfserr;
 269		if (nfsd_mountpoint(dentry, exp)) {
 270			host_err = nfsd_cross_mnt(rqstp, &dentry, &exp);
 271			if (host_err) {
 272				dput(dentry);
 273				goto out_nfserr;
 274			}
 275		}
 276	}
 277	*dentry_ret = dentry;
 278	*exp_ret = exp;
 279	return 0;
 280
 281out_nfserr:
 282	exp_put(exp);
 283	return nfserrno(host_err);
 284}
 285
 286/**
 287 * nfsd_lookup - look up a single path component for nfsd
 288 *
 289 * @rqstp:   the request context
 290 * @fhp:     the file handle of the directory
 291 * @name:    the component name, or %NULL to look up parent
 292 * @len:     length of name to examine
 293 * @resfh:   pointer to pre-initialised filehandle to hold result.
 294 *
 295 * Look up one component of a pathname.
 296 * N.B. After this call _both_ fhp and resfh need an fh_put
 297 *
 298 * If the lookup would cross a mountpoint, and the mounted filesystem
 299 * is exported to the client with NFSEXP_NOHIDE, then the lookup is
 300 * accepted as it stands and the mounted directory is
 301 * returned. Otherwise the covered directory is returned.
 302 * NOTE: this mountpoint crossing is not supported properly by all
 303 *   clients and is explicitly disallowed for NFSv3
 304 *
 305 */
 306__be32
 307nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
 308	    unsigned int len, struct svc_fh *resfh)
 309{
 310	struct svc_export	*exp;
 311	struct dentry		*dentry;
 312	__be32 err;
 313
 314	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
 315	if (err)
 316		return err;
 317	err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
 318	if (err)
 319		return err;
 320	err = check_nfsd_access(exp, rqstp);
 321	if (err)
 322		goto out;
 323	/*
 324	 * Note: we compose the file handle now, but as the
 325	 * dentry may be negative, it may need to be updated.
 326	 */
 327	err = fh_compose(resfh, exp, dentry, fhp);
 328	if (!err && d_really_is_negative(dentry))
 329		err = nfserr_noent;
 330out:
 331	dput(dentry);
 332	exp_put(exp);
 333	return err;
 334}
 335
 336/*
 337 * Commit metadata changes to stable storage.
 338 */
 339static int
 340commit_inode_metadata(struct inode *inode)
 341{
 342	const struct export_operations *export_ops = inode->i_sb->s_export_op;
 343
 344	if (export_ops->commit_metadata)
 345		return export_ops->commit_metadata(inode);
 346	return sync_inode_metadata(inode, 1);
 347}
 348
 349static int
 350commit_metadata(struct svc_fh *fhp)
 351{
 352	struct inode *inode = d_inode(fhp->fh_dentry);
 353
 354	if (!EX_ISSYNC(fhp->fh_export))
 355		return 0;
 356	return commit_inode_metadata(inode);
 357}
 358
 359/*
 360 * Go over the attributes and take care of the small differences between
 361 * NFS semantics and what Linux expects.
 362 */
 363static void
 364nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
 365{
 366	/* Ignore mode updates on symlinks */
 367	if (S_ISLNK(inode->i_mode))
 368		iap->ia_valid &= ~ATTR_MODE;
 369
 370	/* sanitize the mode change */
 371	if (iap->ia_valid & ATTR_MODE) {
 372		iap->ia_mode &= S_IALLUGO;
 373		iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
 374	}
 375
 376	/* Revoke setuid/setgid on chown */
 377	if (!S_ISDIR(inode->i_mode) &&
 378	    ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
 379		iap->ia_valid |= ATTR_KILL_PRIV;
 380		if (iap->ia_valid & ATTR_MODE) {
 381			/* we're setting mode too, just clear the s*id bits */
 382			iap->ia_mode &= ~S_ISUID;
 383			if (iap->ia_mode & S_IXGRP)
 384				iap->ia_mode &= ~S_ISGID;
 385		} else {
 386			/* set ATTR_KILL_* bits and let VFS handle it */
 387			iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
 388		}
 389	}
 390}
 391
 392static __be32
 393nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
 394		struct iattr *iap)
 395{
 396	struct inode *inode = d_inode(fhp->fh_dentry);
 397
 398	if (iap->ia_size < inode->i_size) {
 399		__be32 err;
 400
 401		err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
 402				NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
 403		if (err)
 404			return err;
 405	}
 406	return nfserrno(get_write_access(inode));
 407}
 408
 409static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
 410{
 411	int host_err;
 412
 413	if (iap->ia_valid & ATTR_SIZE) {
 414		/*
 415		 * RFC5661, Section 18.30.4:
 416		 *   Changing the size of a file with SETATTR indirectly
 417		 *   changes the time_modify and change attributes.
 418		 *
 419		 * (and similar for the older RFCs)
 420		 */
 421		struct iattr size_attr = {
 422			.ia_valid	= ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
 423			.ia_size	= iap->ia_size,
 424		};
 425
 426		if (iap->ia_size < 0)
 427			return -EFBIG;
 428
 429		host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
 430		if (host_err)
 431			return host_err;
 432		iap->ia_valid &= ~ATTR_SIZE;
 433
 434		/*
 435		 * Avoid the additional setattr call below if the only other
 436		 * attribute that the client sends is the mtime, as we update
 437		 * it as part of the size change above.
 438		 */
 439		if ((iap->ia_valid & ~ATTR_MTIME) == 0)
 440			return 0;
 441	}
 442
 443	if (!iap->ia_valid)
 444		return 0;
 445
 446	iap->ia_valid |= ATTR_CTIME;
 447	return notify_change(&init_user_ns, dentry, iap, NULL);
 448}
 449
 450/**
 451 * nfsd_setattr - Set various file attributes.
 452 * @rqstp: controlling RPC transaction
 453 * @fhp: filehandle of target
 454 * @attr: attributes to set
 455 * @check_guard: set to 1 if guardtime is a valid timestamp
 456 * @guardtime: do not act if ctime.tv_sec does not match this timestamp
 457 *
 458 * This call may adjust the contents of @attr (in particular, this
 459 * call may change the bits in the na_iattr.ia_valid field).
 460 *
 461 * Returns nfs_ok on success, otherwise an NFS status code is
 462 * returned. Caller must release @fhp by calling fh_put in either
 463 * case.
 464 */
 465__be32
 466nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 467	     struct nfsd_attrs *attr,
 468	     int check_guard, time64_t guardtime)
 469{
 470	struct dentry	*dentry;
 471	struct inode	*inode;
 472	struct iattr	*iap = attr->na_iattr;
 473	int		accmode = NFSD_MAY_SATTR;
 474	umode_t		ftype = 0;
 475	__be32		err;
 476	int		host_err;
 477	bool		get_write_count;
 478	bool		size_change = (iap->ia_valid & ATTR_SIZE);
 479	int		retries;
 480
 481	if (iap->ia_valid & ATTR_SIZE) {
 482		accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
 483		ftype = S_IFREG;
 484	}
 485
 486	/*
 487	 * If utimes(2) and friends are called with times not NULL, we should
 488	 * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
 489	 * will return EACCES, when the caller's effective UID does not match
 490	 * the owner of the file, and the caller is not privileged. In this
 491	 * situation, we should return EPERM(notify_change will return this).
 492	 */
 493	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
 494		accmode |= NFSD_MAY_OWNER_OVERRIDE;
 495		if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
 496			accmode |= NFSD_MAY_WRITE;
 497	}
 498
 499	/* Callers that do fh_verify should do the fh_want_write: */
 500	get_write_count = !fhp->fh_dentry;
 501
 502	/* Get inode */
 503	err = fh_verify(rqstp, fhp, ftype, accmode);
 504	if (err)
 505		return err;
 506	if (get_write_count) {
 507		host_err = fh_want_write(fhp);
 508		if (host_err)
 509			goto out;
 510	}
 511
 512	dentry = fhp->fh_dentry;
 513	inode = d_inode(dentry);
 514
 515	nfsd_sanitize_attrs(inode, iap);
 516
 517	if (check_guard && guardtime != inode->i_ctime.tv_sec)
 518		return nfserr_notsync;
 519
 520	/*
 521	 * The size case is special, it changes the file in addition to the
 522	 * attributes, and file systems don't expect it to be mixed with
 523	 * "random" attribute changes.  We thus split out the size change
 524	 * into a separate call to ->setattr, and do the rest as a separate
 525	 * setattr call.
 526	 */
 527	if (size_change) {
 528		err = nfsd_get_write_access(rqstp, fhp, iap);
 529		if (err)
 530			return err;
 531	}
 532
 533	inode_lock(inode);
 534	for (retries = 1;;) {
 535		host_err = __nfsd_setattr(dentry, iap);
 536		if (host_err != -EAGAIN || !retries--)
 537			break;
 538		if (!nfsd_wait_for_delegreturn(rqstp, inode))
 539			break;
 540	}
 541	if (attr->na_seclabel && attr->na_seclabel->len)
 542		attr->na_labelerr = security_inode_setsecctx(dentry,
 543			attr->na_seclabel->data, attr->na_seclabel->len);
 544	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
 545		attr->na_aclerr = set_posix_acl(&init_user_ns,
 546						dentry, ACL_TYPE_ACCESS,
 547						attr->na_pacl);
 548	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
 549	    !attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
 550		attr->na_aclerr = set_posix_acl(&init_user_ns,
 551						dentry, ACL_TYPE_DEFAULT,
 552						attr->na_dpacl);
 553	inode_unlock(inode);
 554	if (size_change)
 555		put_write_access(inode);
 556out:
 557	if (!host_err)
 558		host_err = commit_metadata(fhp);
 559	return nfserrno(host_err);
 560}
 561
 562#if defined(CONFIG_NFSD_V4)
 563/*
 564 * NFS junction information is stored in an extended attribute.
 565 */
 566#define NFSD_JUNCTION_XATTR_NAME	XATTR_TRUSTED_PREFIX "junction.nfs"
 567
 568/**
 569 * nfsd4_is_junction - Test if an object could be an NFS junction
 570 *
 571 * @dentry: object to test
 572 *
 573 * Returns 1 if "dentry" appears to contain NFS junction information.
 574 * Otherwise 0 is returned.
 575 */
 576int nfsd4_is_junction(struct dentry *dentry)
 577{
 578	struct inode *inode = d_inode(dentry);
 579
 580	if (inode == NULL)
 581		return 0;
 582	if (inode->i_mode & S_IXUGO)
 583		return 0;
 584	if (!(inode->i_mode & S_ISVTX))
 585		return 0;
 586	if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
 587			 NULL, 0) <= 0)
 588		return 0;
 589	return 1;
 590}
 591
 592static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
 593{
 594	return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
 595}
 596
 597__be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
 598		struct nfsd_file *nf_src, u64 src_pos,
 599		struct nfsd_file *nf_dst, u64 dst_pos,
 600		u64 count, bool sync)
 601{
 602	struct file *src = nf_src->nf_file;
 603	struct file *dst = nf_dst->nf_file;
 604	errseq_t since;
 605	loff_t cloned;
 606	__be32 ret = 0;
 607
 608	since = READ_ONCE(dst->f_wb_err);
 609	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
 610	if (cloned < 0) {
 611		ret = nfserrno(cloned);
 612		goto out_err;
 613	}
 614	if (count && cloned != count) {
 615		ret = nfserrno(-EINVAL);
 616		goto out_err;
 617	}
 618	if (sync) {
 619		loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
 620		int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
 621
 622		if (!status)
 623			status = filemap_check_wb_err(dst->f_mapping, since);
 624		if (!status)
 625			status = commit_inode_metadata(file_inode(src));
 626		if (status < 0) {
 627			struct nfsd_net *nn = net_generic(nf_dst->nf_net,
 628							  nfsd_net_id);
 629
 630			trace_nfsd_clone_file_range_err(rqstp,
 631					&nfsd4_get_cstate(rqstp)->save_fh,
 632					src_pos,
 633					&nfsd4_get_cstate(rqstp)->current_fh,
 634					dst_pos,
 635					count, status);
 636			nfsd_reset_write_verifier(nn);
 637			trace_nfsd_writeverf_reset(nn, rqstp, status);
 638			ret = nfserrno(status);
 639		}
 640	}
 641out_err:
 642	return ret;
 643}
 644
 645ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
 646			     u64 dst_pos, u64 count)
 647{
 648	ssize_t ret;
 649
 650	/*
 651	 * Limit copy to 4MB to prevent indefinitely blocking an nfsd
 652	 * thread and client rpc slot.  The choice of 4MB is somewhat
 653	 * arbitrary.  We might instead base this on r/wsize, or make it
 654	 * tunable, or use a time instead of a byte limit, or implement
 655	 * asynchronous copy.  In theory a client could also recognize a
 656	 * limit like this and pipeline multiple COPY requests.
 657	 */
 658	count = min_t(u64, count, 1 << 22);
 659	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
 660
 661	if (ret == -EOPNOTSUPP || ret == -EXDEV)
 662		ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,
 663					  COPY_FILE_SPLICE);
 664	return ret;
 665}
 666
 667__be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
 668			   struct file *file, loff_t offset, loff_t len,
 669			   int flags)
 670{
 671	int error;
 672
 673	if (!S_ISREG(file_inode(file)->i_mode))
 674		return nfserr_inval;
 675
 676	error = vfs_fallocate(file, flags, offset, len);
 677	if (!error)
 678		error = commit_metadata(fhp);
 679
 680	return nfserrno(error);
 681}
 682#endif /* defined(CONFIG_NFSD_V4) */
 683
 684/*
 685 * Check server access rights to a file system object
 686 */
 687struct accessmap {
 688	u32		access;
 689	int		how;
 690};
 691static struct accessmap	nfs3_regaccess[] = {
 692    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
 693    {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
 694    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_TRUNC	},
 695    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE			},
 696
 697#ifdef CONFIG_NFSD_V4
 698    {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
 699    {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
 700    {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
 701#endif
 702
 703    {	0,			0				}
 704};
 705
 706static struct accessmap	nfs3_diraccess[] = {
 707    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
 708    {	NFS3_ACCESS_LOOKUP,	NFSD_MAY_EXEC			},
 709    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
 710    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_EXEC|NFSD_MAY_WRITE	},
 711    {	NFS3_ACCESS_DELETE,	NFSD_MAY_REMOVE			},
 712
 713#ifdef CONFIG_NFSD_V4
 714    {	NFS4_ACCESS_XAREAD,	NFSD_MAY_READ			},
 715    {	NFS4_ACCESS_XAWRITE,	NFSD_MAY_WRITE			},
 716    {	NFS4_ACCESS_XALIST,	NFSD_MAY_READ			},
 717#endif
 718
 719    {	0,			0				}
 720};
 721
 722static struct accessmap	nfs3_anyaccess[] = {
 723	/* Some clients - Solaris 2.6 at least, make an access call
 724	 * to the server to check for access for things like /dev/null
 725	 * (which really, the server doesn't care about).  So
 726	 * We provide simple access checking for them, looking
 727	 * mainly at mode bits, and we make sure to ignore read-only
 728	 * filesystem checks
 729	 */
 730    {	NFS3_ACCESS_READ,	NFSD_MAY_READ			},
 731    {	NFS3_ACCESS_EXECUTE,	NFSD_MAY_EXEC			},
 732    {	NFS3_ACCESS_MODIFY,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
 733    {	NFS3_ACCESS_EXTEND,	NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS	},
 734
 735    {	0,			0				}
 736};
 737
 738__be32
 739nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
 740{
 741	struct accessmap	*map;
 742	struct svc_export	*export;
 743	struct dentry		*dentry;
 744	u32			query, result = 0, sresult = 0;
 745	__be32			error;
 746
 747	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
 748	if (error)
 749		goto out;
 750
 751	export = fhp->fh_export;
 752	dentry = fhp->fh_dentry;
 753
 754	if (d_is_reg(dentry))
 755		map = nfs3_regaccess;
 756	else if (d_is_dir(dentry))
 757		map = nfs3_diraccess;
 758	else
 759		map = nfs3_anyaccess;
 760
 761
 762	query = *access;
 763	for  (; map->access; map++) {
 764		if (map->access & query) {
 765			__be32 err2;
 766
 767			sresult |= map->access;
 768
 769			err2 = nfsd_permission(rqstp, export, dentry, map->how);
 770			switch (err2) {
 771			case nfs_ok:
 772				result |= map->access;
 773				break;
 774				
 775			/* the following error codes just mean the access was not allowed,
 776			 * rather than an error occurred */
 777			case nfserr_rofs:
 778			case nfserr_acces:
 779			case nfserr_perm:
 780				/* simply don't "or" in the access bit. */
 781				break;
 782			default:
 783				error = err2;
 784				goto out;
 785			}
 786		}
 787	}
 788	*access = result;
 789	if (supported)
 790		*supported = sresult;
 791
 792 out:
 793	return error;
 794}
 795
 796int nfsd_open_break_lease(struct inode *inode, int access)
 797{
 798	unsigned int mode;
 799
 800	if (access & NFSD_MAY_NOT_BREAK_LEASE)
 801		return 0;
 802	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
 803	return break_lease(inode, mode | O_NONBLOCK);
 804}
 805
 806/*
 807 * Open an existing file or directory.
 808 * The may_flags argument indicates the type of open (read/write/lock)
 809 * and additional flags.
 810 * N.B. After this call fhp needs an fh_put
 811 */
 812static __be32
 813__nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 814			int may_flags, struct file **filp)
 815{
 816	struct path	path;
 817	struct inode	*inode;
 818	struct file	*file;
 819	int		flags = O_RDONLY|O_LARGEFILE;
 820	__be32		err;
 821	int		host_err = 0;
 822
 823	path.mnt = fhp->fh_export->ex_path.mnt;
 824	path.dentry = fhp->fh_dentry;
 825	inode = d_inode(path.dentry);
 826
 827	err = nfserr_perm;
 828	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
 829		goto out;
 830
 831	if (!inode->i_fop)
 832		goto out;
 833
 834	host_err = nfsd_open_break_lease(inode, may_flags);
 835	if (host_err) /* NOMEM or WOULDBLOCK */
 836		goto out_nfserr;
 837
 838	if (may_flags & NFSD_MAY_WRITE) {
 839		if (may_flags & NFSD_MAY_READ)
 840			flags = O_RDWR|O_LARGEFILE;
 841		else
 842			flags = O_WRONLY|O_LARGEFILE;
 843	}
 844
 845	file = dentry_open(&path, flags, current_cred());
 846	if (IS_ERR(file)) {
 847		host_err = PTR_ERR(file);
 848		goto out_nfserr;
 849	}
 850
 851	host_err = ima_file_check(file, may_flags);
 852	if (host_err) {
 853		fput(file);
 854		goto out_nfserr;
 855	}
 856
 857	if (may_flags & NFSD_MAY_64BIT_COOKIE)
 858		file->f_mode |= FMODE_64BITHASH;
 859	else
 860		file->f_mode |= FMODE_32BITHASH;
 861
 862	*filp = file;
 863out_nfserr:
 864	err = nfserrno(host_err);
 865out:
 866	return err;
 867}
 868
 869__be32
 870nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
 871		int may_flags, struct file **filp)
 872{
 873	__be32 err;
 874	bool retried = false;
 875
 876	validate_process_creds();
 877	/*
 878	 * If we get here, then the client has already done an "open",
 879	 * and (hopefully) checked permission - so allow OWNER_OVERRIDE
 880	 * in case a chmod has now revoked permission.
 881	 *
 882	 * Arguably we should also allow the owner override for
 883	 * directories, but we never have and it doesn't seem to have
 884	 * caused anyone a problem.  If we were to change this, note
 885	 * also that our filldir callbacks would need a variant of
 886	 * lookup_one_len that doesn't check permissions.
 887	 */
 888	if (type == S_IFREG)
 889		may_flags |= NFSD_MAY_OWNER_OVERRIDE;
 890retry:
 891	err = fh_verify(rqstp, fhp, type, may_flags);
 892	if (!err) {
 893		err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
 894		if (err == nfserr_stale && !retried) {
 895			retried = true;
 896			fh_put(fhp);
 897			goto retry;
 898		}
 899	}
 900	validate_process_creds();
 901	return err;
 902}
 903
 904/**
 905 * nfsd_open_verified - Open a regular file for the filecache
 906 * @rqstp: RPC request
 907 * @fhp: NFS filehandle of the file to open
 908 * @may_flags: internal permission flags
 909 * @filp: OUT: open "struct file *"
 910 *
 911 * Returns an nfsstat value in network byte order.
 912 */
 913__be32
 914nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
 915		   struct file **filp)
 916{
 917	__be32 err;
 918
 919	validate_process_creds();
 920	err = __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
 921	validate_process_creds();
 922	return err;
 923}
 924
 925/*
 926 * Grab and keep cached pages associated with a file in the svc_rqst
 927 * so that they can be passed to the network sendmsg/sendpage routines
 928 * directly. They will be released after the sending has completed.
 929 */
 930static int
 931nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 932		  struct splice_desc *sd)
 933{
 934	struct svc_rqst *rqstp = sd->u.data;
 935	struct page *page = buf->page;	// may be a compound one
 936	unsigned offset = buf->offset;
 937	struct page *last_page;
 938
 939	last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
 940	for (page += offset / PAGE_SIZE; page <= last_page; page++)
 941		svc_rqst_replace_page(rqstp, page);
 942	if (rqstp->rq_res.page_len == 0)	// first call
 943		rqstp->rq_res.page_base = offset % PAGE_SIZE;
 944	rqstp->rq_res.page_len += sd->len;
 945	return sd->len;
 946}
 947
 948static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
 949				    struct splice_desc *sd)
 950{
 951	return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
 952}
 953
 954static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
 955		size_t expected)
 956{
 957	if (expected != 0 && len == 0)
 958		return 1;
 959	if (offset+len >= i_size_read(file_inode(file)))
 960		return 1;
 961	return 0;
 962}
 963
 964static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 965			       struct file *file, loff_t offset,
 966			       unsigned long *count, u32 *eof, ssize_t host_err)
 967{
 968	if (host_err >= 0) {
 969		nfsd_stats_io_read_add(fhp->fh_export, host_err);
 970		*eof = nfsd_eof_on_read(file, offset, host_err, *count);
 971		*count = host_err;
 972		fsnotify_access(file);
 973		trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
 974		return 0;
 975	} else {
 976		trace_nfsd_read_err(rqstp, fhp, offset, host_err);
 977		return nfserrno(host_err);
 978	}
 979}
 980
 981__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 982			struct file *file, loff_t offset, unsigned long *count,
 983			u32 *eof)
 984{
 985	struct splice_desc sd = {
 986		.len		= 0,
 987		.total_len	= *count,
 988		.pos		= offset,
 989		.u.data		= rqstp,
 990	};
 991	ssize_t host_err;
 992
 993	trace_nfsd_read_splice(rqstp, fhp, offset, *count);
 994	rqstp->rq_next_page = rqstp->rq_respages + 1;
 995	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
 996	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 997}
 998
 999__be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
1000		  struct file *file, loff_t offset,
1001		  struct kvec *vec, int vlen, unsigned long *count,
1002		  u32 *eof)
1003{
1004	struct iov_iter iter;
1005	loff_t ppos = offset;
1006	ssize_t host_err;
1007
1008	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
1009	iov_iter_kvec(&iter, ITER_DEST, vec, vlen, *count);
1010	host_err = vfs_iter_read(file, &iter, &ppos, 0);
1011	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1012}
1013
1014/*
1015 * Gathered writes: If another process is currently writing to the file,
1016 * there's a high chance this is another nfsd (triggered by a bulk write
1017 * from a client's biod). Rather than syncing the file with each write
1018 * request, we sleep for 10 msec.
1019 *
1020 * I don't know if this roughly approximates C. Juszak's idea of
1021 * gathered writes, but it's a nice and simple solution (IMHO), and it
1022 * seems to work:-)
1023 *
1024 * Note: we do this only in the NFSv2 case, since v3 and higher have a
1025 * better tool (separate unstable writes and commits) for solving this
1026 * problem.
1027 */
1028static int wait_for_concurrent_writes(struct file *file)
1029{
1030	struct inode *inode = file_inode(file);
1031	static ino_t last_ino;
1032	static dev_t last_dev;
1033	int err = 0;
1034
1035	if (atomic_read(&inode->i_writecount) > 1
1036	    || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
1037		dprintk("nfsd: write defer %d\n", task_pid_nr(current));
1038		msleep(10);
1039		dprintk("nfsd: write resume %d\n", task_pid_nr(current));
1040	}
1041
1042	if (inode->i_state & I_DIRTY) {
1043		dprintk("nfsd: write sync %d\n", task_pid_nr(current));
1044		err = vfs_fsync(file, 0);
1045	}
1046	last_ino = inode->i_ino;
1047	last_dev = inode->i_sb->s_dev;
1048	return err;
1049}
1050
1051__be32
1052nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1053				loff_t offset, struct kvec *vec, int vlen,
1054				unsigned long *cnt, int stable,
1055				__be32 *verf)
1056{
1057	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
1058	struct file		*file = nf->nf_file;
1059	struct super_block	*sb = file_inode(file)->i_sb;
1060	struct svc_export	*exp;
1061	struct iov_iter		iter;
1062	errseq_t		since;
1063	__be32			nfserr;
1064	int			host_err;
1065	int			use_wgather;
1066	loff_t			pos = offset;
1067	unsigned long		exp_op_flags = 0;
1068	unsigned int		pflags = current->flags;
1069	rwf_t			flags = 0;
1070	bool			restore_flags = false;
1071
1072	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
1073
1074	if (sb->s_export_op)
1075		exp_op_flags = sb->s_export_op->flags;
1076
1077	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
1078	    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1079		/*
1080		 * We want throttling in balance_dirty_pages()
1081		 * and shrink_inactive_list() to only consider
1082		 * the backingdev we are writing to, so that nfs to
1083		 * localhost doesn't cause nfsd to lock up due to all
1084		 * the client's dirty pages or its congested queue.
1085		 */
1086		current->flags |= PF_LOCAL_THROTTLE;
1087		restore_flags = true;
1088	}
1089
1090	exp = fhp->fh_export;
1091	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1092
1093	if (!EX_ISSYNC(exp))
1094		stable = NFS_UNSTABLE;
1095
1096	if (stable && !use_wgather)
1097		flags |= RWF_SYNC;
1098
1099	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
1100	since = READ_ONCE(file->f_wb_err);
1101	if (verf)
1102		nfsd_copy_write_verifier(verf, nn);
1103	host_err = vfs_iter_write(file, &iter, &pos, flags);
1104	if (host_err < 0) {
1105		nfsd_reset_write_verifier(nn);
1106		trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1107		goto out_nfserr;
1108	}
1109	*cnt = host_err;
1110	nfsd_stats_io_write_add(exp, *cnt);
1111	fsnotify_modify(file);
1112	host_err = filemap_check_wb_err(file->f_mapping, since);
1113	if (host_err < 0)
1114		goto out_nfserr;
1115
1116	if (stable && use_wgather) {
1117		host_err = wait_for_concurrent_writes(file);
1118		if (host_err < 0) {
1119			nfsd_reset_write_verifier(nn);
1120			trace_nfsd_writeverf_reset(nn, rqstp, host_err);
1121		}
1122	}
1123
1124out_nfserr:
1125	if (host_err >= 0) {
1126		trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1127		nfserr = nfs_ok;
1128	} else {
1129		trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1130		nfserr = nfserrno(host_err);
1131	}
1132	if (restore_flags)
1133		current_restore_flags(pflags, PF_LOCAL_THROTTLE);
1134	return nfserr;
1135}
1136
1137/*
1138 * Read data from a file. count must contain the requested read count
1139 * on entry. On return, *count contains the number of bytes actually read.
1140 * N.B. After this call fhp needs an fh_put
1141 */
1142__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1143	loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
1144	u32 *eof)
1145{
1146	struct nfsd_file	*nf;
1147	struct file *file;
1148	__be32 err;
1149
1150	trace_nfsd_read_start(rqstp, fhp, offset, *count);
1151	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, &nf);
1152	if (err)
1153		return err;
1154
1155	file = nf->nf_file;
1156	if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1157		err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1158	else
1159		err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
1160
1161	nfsd_file_put(nf);
1162
1163	trace_nfsd_read_done(rqstp, fhp, offset, *count);
1164
1165	return err;
1166}
1167
1168/*
1169 * Write data to a file.
1170 * The stable flag requests synchronous writes.
1171 * N.B. After this call fhp needs an fh_put
1172 */
1173__be32
1174nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1175	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1176	   __be32 *verf)
1177{
1178	struct nfsd_file *nf;
1179	__be32 err;
1180
1181	trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1182
1183	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, &nf);
1184	if (err)
1185		goto out;
1186
1187	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1188			vlen, cnt, stable, verf);
1189	nfsd_file_put(nf);
1190out:
1191	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1192	return err;
1193}
1194
1195/**
1196 * nfsd_commit - Commit pending writes to stable storage
1197 * @rqstp: RPC request being processed
1198 * @fhp: NFS filehandle
1199 * @nf: target file
1200 * @offset: raw offset from beginning of file
1201 * @count: raw count of bytes to sync
1202 * @verf: filled in with the server's current write verifier
1203 *
1204 * Note: we guarantee that data that lies within the range specified
1205 * by the 'offset' and 'count' parameters will be synced. The server
1206 * is permitted to sync data that lies outside this range at the
1207 * same time.
1208 *
1209 * Unfortunately we cannot lock the file to make sure we return full WCC
1210 * data to the client, as locking happens lower down in the filesystem.
1211 *
1212 * Return values:
1213 *   An nfsstat value in network byte order.
1214 */
1215__be32
1216nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1217	    u64 offset, u32 count, __be32 *verf)
1218{
1219	__be32			err = nfs_ok;
1220	u64			maxbytes;
1221	loff_t			start, end;
1222	struct nfsd_net		*nn;
1223
1224	/*
1225	 * Convert the client-provided (offset, count) range to a
1226	 * (start, end) range. If the client-provided range falls
1227	 * outside the maximum file size of the underlying FS,
1228	 * clamp the sync range appropriately.
1229	 */
1230	start = 0;
1231	end = LLONG_MAX;
1232	maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
1233	if (offset < maxbytes) {
1234		start = offset;
1235		if (count && (offset + count - 1 < maxbytes))
1236			end = offset + count - 1;
1237	}
1238
1239	nn = net_generic(nf->nf_net, nfsd_net_id);
1240	if (EX_ISSYNC(fhp->fh_export)) {
1241		errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
1242		int err2;
1243
1244		err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
1245		switch (err2) {
1246		case 0:
1247			nfsd_copy_write_verifier(verf, nn);
1248			err2 = filemap_check_wb_err(nf->nf_file->f_mapping,
1249						    since);
1250			err = nfserrno(err2);
1251			break;
1252		case -EINVAL:
1253			err = nfserr_notsupp;
1254			break;
1255		default:
1256			nfsd_reset_write_verifier(nn);
1257			trace_nfsd_writeverf_reset(nn, rqstp, err2);
1258			err = nfserrno(err2);
1259		}
1260	} else
1261		nfsd_copy_write_verifier(verf, nn);
1262
1263	return err;
1264}
1265
1266/**
1267 * nfsd_create_setattr - Set a created file's attributes
1268 * @rqstp: RPC transaction being executed
1269 * @fhp: NFS filehandle of parent directory
1270 * @resfhp: NFS filehandle of new object
1271 * @attrs: requested attributes of new object
1272 *
1273 * Returns nfs_ok on success, or an nfsstat in network byte order.
1274 */
1275__be32
1276nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
1277		    struct svc_fh *resfhp, struct nfsd_attrs *attrs)
1278{
1279	struct iattr *iap = attrs->na_iattr;
1280	__be32 status;
1281
1282	/*
1283	 * Mode has already been set by file creation.
1284	 */
1285	iap->ia_valid &= ~ATTR_MODE;
1286
1287	/*
1288	 * Setting uid/gid works only for root.  Irix appears to
1289	 * send along the gid on create when it tries to implement
1290	 * setgid directories via NFS:
1291	 */
1292	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1293		iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1294
1295	/*
1296	 * Callers expect new file metadata to be committed even
1297	 * if the attributes have not changed.
1298	 */
1299	if (iap->ia_valid)
1300		status = nfsd_setattr(rqstp, resfhp, attrs, 0, (time64_t)0);
1301	else
1302		status = nfserrno(commit_metadata(resfhp));
1303
1304	/*
1305	 * Transactional filesystems had a chance to commit changes
1306	 * for both parent and child simultaneously making the
1307	 * following commit_metadata a noop in many cases.
1308	 */
1309	if (!status)
1310		status = nfserrno(commit_metadata(fhp));
1311
1312	/*
1313	 * Update the new filehandle to pick up the new attributes.
1314	 */
1315	if (!status)
1316		status = fh_update(resfhp);
1317
1318	return status;
1319}
1320
1321/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1322 * setting size to 0 may fail for some specific file systems by the permission
1323 * checking which requires WRITE permission but the mode is 000.
1324 * we ignore the resizing(to 0) on the just new created file, since the size is
1325 * 0 after file created.
1326 *
1327 * call this only after vfs_create() is called.
1328 * */
1329static void
1330nfsd_check_ignore_resizing(struct iattr *iap)
1331{
1332	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1333		iap->ia_valid &= ~ATTR_SIZE;
1334}
1335
1336/* The parent directory should already be locked: */
1337__be32
1338nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1339		   struct nfsd_attrs *attrs,
1340		   int type, dev_t rdev, struct svc_fh *resfhp)
1341{
1342	struct dentry	*dentry, *dchild;
1343	struct inode	*dirp;
1344	struct iattr	*iap = attrs->na_iattr;
1345	__be32		err;
1346	int		host_err;
1347
1348	dentry = fhp->fh_dentry;
1349	dirp = d_inode(dentry);
1350
1351	dchild = dget(resfhp->fh_dentry);
1352	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1353	if (err)
1354		goto out;
1355
1356	if (!(iap->ia_valid & ATTR_MODE))
1357		iap->ia_mode = 0;
1358	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1359
1360	if (!IS_POSIXACL(dirp))
1361		iap->ia_mode &= ~current_umask();
1362
1363	err = 0;
1364	switch (type) {
1365	case S_IFREG:
1366		host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
1367		if (!host_err)
1368			nfsd_check_ignore_resizing(iap);
1369		break;
1370	case S_IFDIR:
1371		host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
1372		if (!host_err && unlikely(d_unhashed(dchild))) {
1373			struct dentry *d;
1374			d = lookup_one_len(dchild->d_name.name,
1375					   dchild->d_parent,
1376					   dchild->d_name.len);
1377			if (IS_ERR(d)) {
1378				host_err = PTR_ERR(d);
1379				break;
1380			}
1381			if (unlikely(d_is_negative(d))) {
1382				dput(d);
1383				err = nfserr_serverfault;
1384				goto out;
1385			}
1386			dput(resfhp->fh_dentry);
1387			resfhp->fh_dentry = dget(d);
1388			err = fh_update(resfhp);
1389			dput(dchild);
1390			dchild = d;
1391			if (err)
1392				goto out;
1393		}
1394		break;
1395	case S_IFCHR:
1396	case S_IFBLK:
1397	case S_IFIFO:
1398	case S_IFSOCK:
1399		host_err = vfs_mknod(&init_user_ns, dirp, dchild,
1400				     iap->ia_mode, rdev);
1401		break;
1402	default:
1403		printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1404		       type);
1405		host_err = -EINVAL;
1406	}
1407	if (host_err < 0)
1408		goto out_nfserr;
1409
1410	err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1411
1412out:
1413	dput(dchild);
1414	return err;
1415
1416out_nfserr:
1417	err = nfserrno(host_err);
1418	goto out;
1419}
1420
1421/*
1422 * Create a filesystem object (regular, directory, special).
1423 * Note that the parent directory is left locked.
1424 *
1425 * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1426 */
1427__be32
1428nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1429	    char *fname, int flen, struct nfsd_attrs *attrs,
1430	    int type, dev_t rdev, struct svc_fh *resfhp)
1431{
1432	struct dentry	*dentry, *dchild = NULL;
1433	__be32		err;
1434	int		host_err;
1435
1436	if (isdotent(fname, flen))
1437		return nfserr_exist;
1438
1439	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1440	if (err)
1441		return err;
1442
1443	dentry = fhp->fh_dentry;
1444
1445	host_err = fh_want_write(fhp);
1446	if (host_err)
1447		return nfserrno(host_err);
1448
1449	inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
1450	dchild = lookup_one_len(fname, dentry, flen);
1451	host_err = PTR_ERR(dchild);
1452	if (IS_ERR(dchild)) {
1453		err = nfserrno(host_err);
1454		goto out_unlock;
1455	}
1456	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1457	/*
1458	 * We unconditionally drop our ref to dchild as fh_compose will have
1459	 * already grabbed its own ref for it.
1460	 */
1461	dput(dchild);
1462	if (err)
1463		goto out_unlock;
1464	fh_fill_pre_attrs(fhp);
1465	err = nfsd_create_locked(rqstp, fhp, attrs, type, rdev, resfhp);
1466	fh_fill_post_attrs(fhp);
1467out_unlock:
1468	inode_unlock(dentry->d_inode);
1469	return err;
1470}
1471
1472/*
1473 * Read a symlink. On entry, *lenp must contain the maximum path length that
1474 * fits into the buffer. On return, it contains the true length.
1475 * N.B. After this call fhp needs an fh_put
1476 */
1477__be32
1478nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1479{
1480	__be32		err;
1481	const char *link;
1482	struct path path;
1483	DEFINE_DELAYED_CALL(done);
1484	int len;
1485
1486	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1487	if (unlikely(err))
1488		return err;
1489
1490	path.mnt = fhp->fh_export->ex_path.mnt;
1491	path.dentry = fhp->fh_dentry;
1492
1493	if (unlikely(!d_is_symlink(path.dentry)))
1494		return nfserr_inval;
1495
1496	touch_atime(&path);
1497
1498	link = vfs_get_link(path.dentry, &done);
1499	if (IS_ERR(link))
1500		return nfserrno(PTR_ERR(link));
1501
1502	len = strlen(link);
1503	if (len < *lenp)
1504		*lenp = len;
1505	memcpy(buf, link, *lenp);
1506	do_delayed_call(&done);
1507	return 0;
1508}
1509
1510/**
1511 * nfsd_symlink - Create a symlink and look up its inode
1512 * @rqstp: RPC transaction being executed
1513 * @fhp: NFS filehandle of parent directory
1514 * @fname: filename of the new symlink
1515 * @flen: length of @fname
1516 * @path: content of the new symlink (NUL-terminated)
1517 * @attrs: requested attributes of new object
1518 * @resfhp: NFS filehandle of new object
1519 *
1520 * N.B. After this call _both_ fhp and resfhp need an fh_put
1521 *
1522 * Returns nfs_ok on success, or an nfsstat in network byte order.
1523 */
1524__be32
1525nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1526	     char *fname, int flen,
1527	     char *path, struct nfsd_attrs *attrs,
1528	     struct svc_fh *resfhp)
1529{
1530	struct dentry	*dentry, *dnew;
1531	__be32		err, cerr;
1532	int		host_err;
1533
1534	err = nfserr_noent;
1535	if (!flen || path[0] == '\0')
1536		goto out;
1537	err = nfserr_exist;
1538	if (isdotent(fname, flen))
1539		goto out;
1540
1541	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1542	if (err)
1543		goto out;
1544
1545	host_err = fh_want_write(fhp);
1546	if (host_err) {
1547		err = nfserrno(host_err);
1548		goto out;
1549	}
1550
1551	dentry = fhp->fh_dentry;
1552	inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
1553	dnew = lookup_one_len(fname, dentry, flen);
1554	if (IS_ERR(dnew)) {
1555		err = nfserrno(PTR_ERR(dnew));
1556		inode_unlock(dentry->d_inode);
1557		goto out_drop_write;
1558	}
1559	fh_fill_pre_attrs(fhp);
1560	host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
1561	err = nfserrno(host_err);
1562	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1563	if (!err)
1564		nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1565	fh_fill_post_attrs(fhp);
1566	inode_unlock(dentry->d_inode);
1567	if (!err)
1568		err = nfserrno(commit_metadata(fhp));
1569	dput(dnew);
1570	if (err==0) err = cerr;
1571out_drop_write:
1572	fh_drop_write(fhp);
1573out:
1574	return err;
1575}
1576
1577/*
1578 * Create a hardlink
1579 * N.B. After this call _both_ ffhp and tfhp need an fh_put
1580 */
1581__be32
1582nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1583				char *name, int len, struct svc_fh *tfhp)
1584{
1585	struct dentry	*ddir, *dnew, *dold;
1586	struct inode	*dirp;
1587	__be32		err;
1588	int		host_err;
1589
1590	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1591	if (err)
1592		goto out;
1593	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1594	if (err)
1595		goto out;
1596	err = nfserr_isdir;
1597	if (d_is_dir(tfhp->fh_dentry))
1598		goto out;
1599	err = nfserr_perm;
1600	if (!len)
1601		goto out;
1602	err = nfserr_exist;
1603	if (isdotent(name, len))
1604		goto out;
1605
1606	host_err = fh_want_write(tfhp);
1607	if (host_err) {
1608		err = nfserrno(host_err);
1609		goto out;
1610	}
1611
1612	ddir = ffhp->fh_dentry;
1613	dirp = d_inode(ddir);
1614	inode_lock_nested(dirp, I_MUTEX_PARENT);
1615
1616	dnew = lookup_one_len(name, ddir, len);
1617	if (IS_ERR(dnew)) {
1618		err = nfserrno(PTR_ERR(dnew));
1619		goto out_unlock;
1620	}
1621
1622	dold = tfhp->fh_dentry;
1623
1624	err = nfserr_noent;
1625	if (d_really_is_negative(dold))
1626		goto out_dput;
1627	fh_fill_pre_attrs(ffhp);
1628	host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
1629	fh_fill_post_attrs(ffhp);
1630	inode_unlock(dirp);
1631	if (!host_err) {
1632		err = nfserrno(commit_metadata(ffhp));
1633		if (!err)
1634			err = nfserrno(commit_metadata(tfhp));
1635	} else {
1636		if (host_err == -EXDEV && rqstp->rq_vers == 2)
1637			err = nfserr_acces;
1638		else
1639			err = nfserrno(host_err);
1640	}
1641	dput(dnew);
1642out_drop_write:
1643	fh_drop_write(tfhp);
1644out:
1645	return err;
1646
1647out_dput:
1648	dput(dnew);
1649out_unlock:
1650	inode_unlock(dirp);
1651	goto out_drop_write;
1652}
1653
1654static void
1655nfsd_close_cached_files(struct dentry *dentry)
1656{
1657	struct inode *inode = d_inode(dentry);
1658
1659	if (inode && S_ISREG(inode->i_mode))
1660		nfsd_file_close_inode_sync(inode);
1661}
1662
1663static bool
1664nfsd_has_cached_files(struct dentry *dentry)
1665{
1666	bool		ret = false;
1667	struct inode *inode = d_inode(dentry);
1668
1669	if (inode && S_ISREG(inode->i_mode))
1670		ret = nfsd_file_is_cached(inode);
1671	return ret;
1672}
1673
1674/*
1675 * Rename a file
1676 * N.B. After this call _both_ ffhp and tfhp need an fh_put
1677 */
1678__be32
1679nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1680			    struct svc_fh *tfhp, char *tname, int tlen)
1681{
1682	struct dentry	*fdentry, *tdentry, *odentry, *ndentry, *trap;
1683	struct inode	*fdir, *tdir;
1684	__be32		err;
1685	int		host_err;
1686	bool		close_cached = false;
1687
1688	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1689	if (err)
1690		goto out;
1691	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1692	if (err)
1693		goto out;
1694
1695	fdentry = ffhp->fh_dentry;
1696	fdir = d_inode(fdentry);
1697
1698	tdentry = tfhp->fh_dentry;
1699	tdir = d_inode(tdentry);
1700
1701	err = nfserr_perm;
1702	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1703		goto out;
1704
1705retry:
1706	host_err = fh_want_write(ffhp);
1707	if (host_err) {
1708		err = nfserrno(host_err);
1709		goto out;
1710	}
1711
1712	trap = lock_rename(tdentry, fdentry);
1713	fh_fill_pre_attrs(ffhp);
1714	fh_fill_pre_attrs(tfhp);
1715
1716	odentry = lookup_one_len(fname, fdentry, flen);
1717	host_err = PTR_ERR(odentry);
1718	if (IS_ERR(odentry))
1719		goto out_nfserr;
1720
1721	host_err = -ENOENT;
1722	if (d_really_is_negative(odentry))
1723		goto out_dput_old;
1724	host_err = -EINVAL;
1725	if (odentry == trap)
1726		goto out_dput_old;
1727
1728	ndentry = lookup_one_len(tname, tdentry, tlen);
1729	host_err = PTR_ERR(ndentry);
1730	if (IS_ERR(ndentry))
1731		goto out_dput_old;
1732	host_err = -ENOTEMPTY;
1733	if (ndentry == trap)
1734		goto out_dput_new;
1735
1736	host_err = -EXDEV;
1737	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1738		goto out_dput_new;
1739	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1740		goto out_dput_new;
1741
1742	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1743	    nfsd_has_cached_files(ndentry)) {
1744		close_cached = true;
1745		goto out_dput_old;
1746	} else {
1747		struct renamedata rd = {
1748			.old_mnt_userns	= &init_user_ns,
1749			.old_dir	= fdir,
1750			.old_dentry	= odentry,
1751			.new_mnt_userns	= &init_user_ns,
1752			.new_dir	= tdir,
1753			.new_dentry	= ndentry,
1754		};
1755		int retries;
1756
1757		for (retries = 1;;) {
1758			host_err = vfs_rename(&rd);
1759			if (host_err != -EAGAIN || !retries--)
1760				break;
1761			if (!nfsd_wait_for_delegreturn(rqstp, d_inode(odentry)))
1762				break;
1763		}
1764		if (!host_err) {
1765			host_err = commit_metadata(tfhp);
1766			if (!host_err)
1767				host_err = commit_metadata(ffhp);
1768		}
1769	}
1770 out_dput_new:
1771	dput(ndentry);
1772 out_dput_old:
1773	dput(odentry);
1774 out_nfserr:
1775	err = nfserrno(host_err);
1776
1777	if (!close_cached) {
1778		fh_fill_post_attrs(ffhp);
1779		fh_fill_post_attrs(tfhp);
1780	}
1781	unlock_rename(tdentry, fdentry);
1782	fh_drop_write(ffhp);
1783
1784	/*
1785	 * If the target dentry has cached open files, then we need to try to
1786	 * close them prior to doing the rename. Flushing delayed fput
1787	 * shouldn't be done with locks held however, so we delay it until this
1788	 * point and then reattempt the whole shebang.
1789	 */
1790	if (close_cached) {
1791		close_cached = false;
1792		nfsd_close_cached_files(ndentry);
1793		dput(ndentry);
1794		goto retry;
1795	}
1796out:
1797	return err;
1798}
1799
1800/*
1801 * Unlink a file or directory
1802 * N.B. After this call fhp needs an fh_put
1803 */
1804__be32
1805nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1806				char *fname, int flen)
1807{
1808	struct dentry	*dentry, *rdentry;
1809	struct inode	*dirp;
1810	struct inode	*rinode;
1811	__be32		err;
1812	int		host_err;
1813
1814	err = nfserr_acces;
1815	if (!flen || isdotent(fname, flen))
1816		goto out;
1817	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1818	if (err)
1819		goto out;
1820
1821	host_err = fh_want_write(fhp);
1822	if (host_err)
1823		goto out_nfserr;
1824
1825	dentry = fhp->fh_dentry;
1826	dirp = d_inode(dentry);
1827	inode_lock_nested(dirp, I_MUTEX_PARENT);
1828
1829	rdentry = lookup_one_len(fname, dentry, flen);
1830	host_err = PTR_ERR(rdentry);
1831	if (IS_ERR(rdentry))
1832		goto out_unlock;
1833
1834	if (d_really_is_negative(rdentry)) {
1835		dput(rdentry);
1836		host_err = -ENOENT;
1837		goto out_unlock;
1838	}
1839	rinode = d_inode(rdentry);
1840	ihold(rinode);
1841
1842	if (!type)
1843		type = d_inode(rdentry)->i_mode & S_IFMT;
1844
1845	fh_fill_pre_attrs(fhp);
1846	if (type != S_IFDIR) {
1847		int retries;
1848
1849		if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1850			nfsd_close_cached_files(rdentry);
1851
1852		for (retries = 1;;) {
1853			host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
1854			if (host_err != -EAGAIN || !retries--)
1855				break;
1856			if (!nfsd_wait_for_delegreturn(rqstp, rinode))
1857				break;
1858		}
1859	} else {
1860		host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
1861	}
1862	fh_fill_post_attrs(fhp);
1863
1864	inode_unlock(dirp);
1865	if (!host_err)
1866		host_err = commit_metadata(fhp);
1867	dput(rdentry);
1868	iput(rinode);    /* truncate the inode here */
1869
1870out_drop_write:
1871	fh_drop_write(fhp);
1872out_nfserr:
1873	if (host_err == -EBUSY) {
1874		/* name is mounted-on. There is no perfect
1875		 * error status.
1876		 */
1877		if (nfsd_v4client(rqstp))
1878			err = nfserr_file_open;
1879		else
1880			err = nfserr_acces;
1881	} else {
1882		err = nfserrno(host_err);
1883	}
1884out:
1885	return err;
1886out_unlock:
1887	inode_unlock(dirp);
1888	goto out_drop_write;
1889}
1890
1891/*
1892 * We do this buffering because we must not call back into the file
1893 * system's ->lookup() method from the filldir callback. That may well
1894 * deadlock a number of file systems.
1895 *
1896 * This is based heavily on the implementation of same in XFS.
1897 */
1898struct buffered_dirent {
1899	u64		ino;
1900	loff_t		offset;
1901	int		namlen;
1902	unsigned int	d_type;
1903	char		name[];
1904};
1905
1906struct readdir_data {
1907	struct dir_context ctx;
1908	char		*dirent;
1909	size_t		used;
1910	int		full;
1911};
1912
1913static bool nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1914				 int namlen, loff_t offset, u64 ino,
1915				 unsigned int d_type)
1916{
1917	struct readdir_data *buf =
1918		container_of(ctx, struct readdir_data, ctx);
1919	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1920	unsigned int reclen;
1921
1922	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1923	if (buf->used + reclen > PAGE_SIZE) {
1924		buf->full = 1;
1925		return false;
1926	}
1927
1928	de->namlen = namlen;
1929	de->offset = offset;
1930	de->ino = ino;
1931	de->d_type = d_type;
1932	memcpy(de->name, name, namlen);
1933	buf->used += reclen;
1934
1935	return true;
1936}
1937
1938static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
1939				    nfsd_filldir_t func, struct readdir_cd *cdp,
1940				    loff_t *offsetp)
1941{
1942	struct buffered_dirent *de;
1943	int host_err;
1944	int size;
1945	loff_t offset;
1946	struct readdir_data buf = {
1947		.ctx.actor = nfsd_buffered_filldir,
1948		.dirent = (void *)__get_free_page(GFP_KERNEL)
1949	};
1950
1951	if (!buf.dirent)
1952		return nfserrno(-ENOMEM);
1953
1954	offset = *offsetp;
1955
1956	while (1) {
1957		unsigned int reclen;
1958
1959		cdp->err = nfserr_eof; /* will be cleared on successful read */
1960		buf.used = 0;
1961		buf.full = 0;
1962
1963		host_err = iterate_dir(file, &buf.ctx);
1964		if (buf.full)
1965			host_err = 0;
1966
1967		if (host_err < 0)
1968			break;
1969
1970		size = buf.used;
1971
1972		if (!size)
1973			break;
1974
1975		de = (struct buffered_dirent *)buf.dirent;
1976		while (size > 0) {
1977			offset = de->offset;
1978
1979			if (func(cdp, de->name, de->namlen, de->offset,
1980				 de->ino, de->d_type))
1981				break;
1982
1983			if (cdp->err != nfs_ok)
1984				break;
1985
1986			trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
1987
1988			reclen = ALIGN(sizeof(*de) + de->namlen,
1989				       sizeof(u64));
1990			size -= reclen;
1991			de = (struct buffered_dirent *)((char *)de + reclen);
1992		}
1993		if (size > 0) /* We bailed out early */
1994			break;
1995
1996		offset = vfs_llseek(file, 0, SEEK_CUR);
1997	}
1998
1999	free_page((unsigned long)(buf.dirent));
2000
2001	if (host_err)
2002		return nfserrno(host_err);
2003
2004	*offsetp = offset;
2005	return cdp->err;
2006}
2007
2008/*
2009 * Read entries from a directory.
2010 * The  NFSv3/4 verifier we ignore for now.
2011 */
2012__be32
2013nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp, 
2014	     struct readdir_cd *cdp, nfsd_filldir_t func)
2015{
2016	__be32		err;
2017	struct file	*file;
2018	loff_t		offset = *offsetp;
2019	int             may_flags = NFSD_MAY_READ;
2020
2021	/* NFSv2 only supports 32 bit cookies */
2022	if (rqstp->rq_vers > 2)
2023		may_flags |= NFSD_MAY_64BIT_COOKIE;
2024
2025	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
2026	if (err)
2027		goto out;
2028
2029	offset = vfs_llseek(file, offset, SEEK_SET);
2030	if (offset < 0) {
2031		err = nfserrno((int)offset);
2032		goto out_close;
2033	}
2034
2035	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2036
2037	if (err == nfserr_eof || err == nfserr_toosmall)
2038		err = nfs_ok; /* can still be found in ->err */
2039out_close:
2040	fput(file);
2041out:
2042	return err;
2043}
2044
2045/*
2046 * Get file system stats
2047 * N.B. After this call fhp needs an fh_put
2048 */
2049__be32
2050nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2051{
2052	__be32 err;
2053
2054	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2055	if (!err) {
2056		struct path path = {
2057			.mnt	= fhp->fh_export->ex_path.mnt,
2058			.dentry	= fhp->fh_dentry,
2059		};
2060		if (vfs_statfs(&path, stat))
2061			err = nfserr_io;
2062	}
2063	return err;
2064}
2065
2066static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2067{
2068	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2069}
2070
2071#ifdef CONFIG_NFSD_V4
2072/*
2073 * Helper function to translate error numbers. In the case of xattr operations,
2074 * some error codes need to be translated outside of the standard translations.
2075 *
2076 * ENODATA needs to be translated to nfserr_noxattr.
2077 * E2BIG to nfserr_xattr2big.
2078 *
2079 * Additionally, vfs_listxattr can return -ERANGE. This means that the
2080 * file has too many extended attributes to retrieve inside an
2081 * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2082 * filesystems will allow the adding of extended attributes until they hit
2083 * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2084 * So, at that point, the attributes are present and valid, but can't
2085 * be retrieved using listxattr, since the upper level xattr code enforces
2086 * the XATTR_LIST_MAX limit.
2087 *
2088 * This bug means that we need to deal with listxattr returning -ERANGE. The
2089 * best mapping is to return TOOSMALL.
2090 */
2091static __be32
2092nfsd_xattr_errno(int err)
2093{
2094	switch (err) {
2095	case -ENODATA:
2096		return nfserr_noxattr;
2097	case -E2BIG:
2098		return nfserr_xattr2big;
2099	case -ERANGE:
2100		return nfserr_toosmall;
2101	}
2102	return nfserrno(err);
2103}
2104
2105/*
2106 * Retrieve the specified user extended attribute. To avoid always
2107 * having to allocate the maximum size (since we are not getting
2108 * a maximum size from the RPC), do a probe + alloc. Hold a reader
2109 * lock on i_rwsem to prevent the extended attribute from changing
2110 * size while we're doing this.
2111 */
2112__be32
2113nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2114	      void **bufp, int *lenp)
2115{
2116	ssize_t len;
2117	__be32 err;
2118	char *buf;
2119	struct inode *inode;
2120	struct dentry *dentry;
2121
2122	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2123	if (err)
2124		return err;
2125
2126	err = nfs_ok;
2127	dentry = fhp->fh_dentry;
2128	inode = d_inode(dentry);
2129
2130	inode_lock_shared(inode);
2131
2132	len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
2133
2134	/*
2135	 * Zero-length attribute, just return.
2136	 */
2137	if (len == 0) {
2138		*bufp = NULL;
2139		*lenp = 0;
2140		goto out;
2141	}
2142
2143	if (len < 0) {
2144		err = nfsd_xattr_errno(len);
2145		goto out;
2146	}
2147
2148	if (len > *lenp) {
2149		err = nfserr_toosmall;
2150		goto out;
2151	}
2152
2153	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2154	if (buf == NULL) {
2155		err = nfserr_jukebox;
2156		goto out;
2157	}
2158
2159	len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
2160	if (len <= 0) {
2161		kvfree(buf);
2162		buf = NULL;
2163		err = nfsd_xattr_errno(len);
2164	}
2165
2166	*lenp = len;
2167	*bufp = buf;
2168
2169out:
2170	inode_unlock_shared(inode);
2171
2172	return err;
2173}
2174
2175/*
2176 * Retrieve the xattr names. Since we can't know how many are
2177 * user extended attributes, we must get all attributes here,
2178 * and have the XDR encode filter out the "user." ones.
2179 *
2180 * While this could always just allocate an XATTR_LIST_MAX
2181 * buffer, that's a waste, so do a probe + allocate. To
2182 * avoid any changes between the probe and allocate, wrap
2183 * this in inode_lock.
2184 */
2185__be32
2186nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2187	       int *lenp)
2188{
2189	ssize_t len;
2190	__be32 err;
2191	char *buf;
2192	struct inode *inode;
2193	struct dentry *dentry;
2194
2195	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2196	if (err)
2197		return err;
2198
2199	dentry = fhp->fh_dentry;
2200	inode = d_inode(dentry);
2201	*lenp = 0;
2202
2203	inode_lock_shared(inode);
2204
2205	len = vfs_listxattr(dentry, NULL, 0);
2206	if (len <= 0) {
2207		err = nfsd_xattr_errno(len);
2208		goto out;
2209	}
2210
2211	if (len > XATTR_LIST_MAX) {
2212		err = nfserr_xattr2big;
2213		goto out;
2214	}
2215
2216	/*
2217	 * We're holding i_rwsem - use GFP_NOFS.
2218	 */
2219	buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
2220	if (buf == NULL) {
2221		err = nfserr_jukebox;
2222		goto out;
2223	}
2224
2225	len = vfs_listxattr(dentry, buf, len);
2226	if (len <= 0) {
2227		kvfree(buf);
2228		err = nfsd_xattr_errno(len);
2229		goto out;
2230	}
2231
2232	*lenp = len;
2233	*bufp = buf;
2234
2235	err = nfs_ok;
2236out:
2237	inode_unlock_shared(inode);
2238
2239	return err;
2240}
2241
2242/**
2243 * nfsd_removexattr - Remove an extended attribute
2244 * @rqstp: RPC transaction being executed
2245 * @fhp: NFS filehandle of object with xattr to remove
2246 * @name: name of xattr to remove (NUL-terminate)
2247 *
2248 * Pass in a NULL pointer for delegated_inode, and let the client deal
2249 * with NFS4ERR_DELAY (same as with e.g. setattr and remove).
2250 *
2251 * Returns nfs_ok on success, or an nfsstat in network byte order.
2252 */
2253__be32
2254nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2255{
2256	__be32 err;
2257	int ret;
2258
2259	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2260	if (err)
2261		return err;
2262
2263	ret = fh_want_write(fhp);
2264	if (ret)
2265		return nfserrno(ret);
2266
2267	inode_lock(fhp->fh_dentry->d_inode);
2268	fh_fill_pre_attrs(fhp);
2269
2270	ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
2271				       name, NULL);
2272
2273	fh_fill_post_attrs(fhp);
2274	inode_unlock(fhp->fh_dentry->d_inode);
2275	fh_drop_write(fhp);
2276
2277	return nfsd_xattr_errno(ret);
2278}
2279
2280__be32
2281nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2282	      void *buf, u32 len, u32 flags)
2283{
2284	__be32 err;
2285	int ret;
2286
2287	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2288	if (err)
2289		return err;
2290
2291	ret = fh_want_write(fhp);
2292	if (ret)
2293		return nfserrno(ret);
2294	inode_lock(fhp->fh_dentry->d_inode);
2295	fh_fill_pre_attrs(fhp);
2296
2297	ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
2298				    len, flags, NULL);
2299	fh_fill_post_attrs(fhp);
2300	inode_unlock(fhp->fh_dentry->d_inode);
2301	fh_drop_write(fhp);
2302
2303	return nfsd_xattr_errno(ret);
2304}
2305#endif
2306
2307/*
2308 * Check for a user's access permissions to this inode.
2309 */
2310__be32
2311nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2312					struct dentry *dentry, int acc)
2313{
2314	struct inode	*inode = d_inode(dentry);
2315	int		err;
2316
2317	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2318		return 0;
2319#if 0
2320	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2321		acc,
2322		(acc & NFSD_MAY_READ)?	" read"  : "",
2323		(acc & NFSD_MAY_WRITE)?	" write" : "",
2324		(acc & NFSD_MAY_EXEC)?	" exec"  : "",
2325		(acc & NFSD_MAY_SATTR)?	" sattr" : "",
2326		(acc & NFSD_MAY_TRUNC)?	" trunc" : "",
2327		(acc & NFSD_MAY_LOCK)?	" lock"  : "",
2328		(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2329		inode->i_mode,
2330		IS_IMMUTABLE(inode)?	" immut" : "",
2331		IS_APPEND(inode)?	" append" : "",
2332		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");
2333	dprintk("      owner %d/%d user %d/%d\n",
2334		inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2335#endif
2336
2337	/* Normally we reject any write/sattr etc access on a read-only file
2338	 * system.  But if it is IRIX doing check on write-access for a 
2339	 * device special file, we ignore rofs.
2340	 */
2341	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2342		if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2343			if (exp_rdonly(rqstp, exp) ||
2344			    __mnt_is_readonly(exp->ex_path.mnt))
2345				return nfserr_rofs;
2346			if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2347				return nfserr_perm;
2348		}
2349	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2350		return nfserr_perm;
2351
2352	if (acc & NFSD_MAY_LOCK) {
2353		/* If we cannot rely on authentication in NLM requests,
2354		 * just allow locks, otherwise require read permission, or
2355		 * ownership
2356		 */
2357		if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2358			return 0;
2359		else
2360			acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2361	}
2362	/*
2363	 * The file owner always gets access permission for accesses that
2364	 * would normally be checked at open time. This is to make
2365	 * file access work even when the client has done a fchmod(fd, 0).
2366	 *
2367	 * However, `cp foo bar' should fail nevertheless when bar is
2368	 * readonly. A sensible way to do this might be to reject all
2369	 * attempts to truncate a read-only file, because a creat() call
2370	 * always implies file truncation.
2371	 * ... but this isn't really fair.  A process may reasonably call
2372	 * ftruncate on an open file descriptor on a file with perm 000.
2373	 * We must trust the client to do permission checking - using "ACCESS"
2374	 * with NFSv3.
2375	 */
2376	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2377	    uid_eq(inode->i_uid, current_fsuid()))
2378		return 0;
2379
2380	/* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2381	err = inode_permission(&init_user_ns, inode,
2382			       acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2383
2384	/* Allow read access to binaries even when mode 111 */
2385	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2386	     (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2387	      acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2388		err = inode_permission(&init_user_ns, inode, MAY_EXEC);
2389
2390	return err? nfserrno(err) : 0;
2391}