1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * linux/fs/reiserfs/xattr.c
   4 *
   5 * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com>
   6 *
   7 */
   8
   9/*
  10 * In order to implement EA/ACLs in a clean, backwards compatible manner,
  11 * they are implemented as files in a "private" directory.
  12 * Each EA is in it's own file, with the directory layout like so (/ is assumed
  13 * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory,
  14 * directories named using the capital-hex form of the objectid and
  15 * generation number are used. Inside each directory are individual files
  16 * named with the name of the extended attribute.
  17 *
  18 * So, for objectid 12648430, we could have:
  19 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access
  20 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default
  21 * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type
  22 * .. or similar.
  23 *
  24 * The file contents are the text of the EA. The size is known based on the
  25 * stat data describing the file.
  26 *
  27 * In the case of system.posix_acl_access and system.posix_acl_default, since
  28 * these are special cases for filesystem ACLs, they are interpreted by the
  29 * kernel, in addition, they are negatively and positively cached and attached
  30 * to the inode so that unnecessary lookups are avoided.
  31 *
  32 * Locking works like so:
  33 * Directory components (xattr root, xattr dir) are protectd by their i_mutex.
  34 * The xattrs themselves are protected by the xattr_sem.
  35 */
  36
  37#include "reiserfs.h"
  38#include <linux/capability.h>
  39#include <linux/dcache.h>
  40#include <linux/namei.h>
  41#include <linux/errno.h>
  42#include <linux/gfp.h>
  43#include <linux/fs.h>
  44#include <linux/file.h>
  45#include <linux/pagemap.h>
  46#include <linux/xattr.h>
  47#include "xattr.h"
  48#include "acl.h"
  49#include <linux/uaccess.h>
  50#include <net/checksum.h>
  51#include <linux/stat.h>
  52#include <linux/quotaops.h>
  53#include <linux/security.h>
  54#include <linux/posix_acl_xattr.h>
  55
  56#define PRIVROOT_NAME ".reiserfs_priv"
  57#define XAROOT_NAME   "xattrs"
  58
  59
  60/*
  61 * Helpers for inode ops. We do this so that we don't have all the VFS
  62 * overhead and also for proper i_mutex annotation.
  63 * dir->i_mutex must be held for all of them.
  64 */
  65#ifdef CONFIG_REISERFS_FS_XATTR
  66static int xattr_create(struct inode *dir, struct dentry *dentry, int mode)
  67{
  68	BUG_ON(!inode_is_locked(dir));
  69	return dir->i_op->create(&init_user_ns, dir, dentry, mode, true);
  70}
  71#endif
  72
  73static int xattr_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
  74{
  75	BUG_ON(!inode_is_locked(dir));
  76	return dir->i_op->mkdir(&init_user_ns, dir, dentry, mode);
  77}
  78
  79/*
  80 * We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr
  81 * mutation ops aren't called during rename or splace, which are the
  82 * only other users of I_MUTEX_CHILD. It violates the ordering, but that's
  83 * better than allocating another subclass just for this code.
  84 */
  85static int xattr_unlink(struct inode *dir, struct dentry *dentry)
  86{
  87	int error;
  88
  89	BUG_ON(!inode_is_locked(dir));
  90
  91	inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
  92	error = dir->i_op->unlink(dir, dentry);
  93	inode_unlock(d_inode(dentry));
  94
  95	if (!error)
  96		d_delete(dentry);
  97	return error;
  98}
  99
 100static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
 101{
 102	int error;
 103
 104	BUG_ON(!inode_is_locked(dir));
 105
 106	inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
 107	error = dir->i_op->rmdir(dir, dentry);
 108	if (!error)
 109		d_inode(dentry)->i_flags |= S_DEAD;
 110	inode_unlock(d_inode(dentry));
 111	if (!error)
 112		d_delete(dentry);
 113
 114	return error;
 115}
 116
 117#define xattr_may_create(flags)	(!flags || flags & XATTR_CREATE)
 118
 119static struct dentry *open_xa_root(struct super_block *sb, int flags)
 120{
 121	struct dentry *privroot = REISERFS_SB(sb)->priv_root;
 122	struct dentry *xaroot;
 123
 124	if (d_really_is_negative(privroot))
 125		return ERR_PTR(-EOPNOTSUPP);
 126
 127	inode_lock_nested(d_inode(privroot), I_MUTEX_XATTR);
 128
 129	xaroot = dget(REISERFS_SB(sb)->xattr_root);
 130	if (!xaroot)
 131		xaroot = ERR_PTR(-EOPNOTSUPP);
 132	else if (d_really_is_negative(xaroot)) {
 133		int err = -ENODATA;
 134
 135		if (xattr_may_create(flags))
 136			err = xattr_mkdir(d_inode(privroot), xaroot, 0700);
 137		if (err) {
 138			dput(xaroot);
 139			xaroot = ERR_PTR(err);
 140		}
 141	}
 142
 143	inode_unlock(d_inode(privroot));
 144	return xaroot;
 145}
 146
 147static struct dentry *open_xa_dir(const struct inode *inode, int flags)
 148{
 149	struct dentry *xaroot, *xadir;
 150	char namebuf[17];
 151
 152	xaroot = open_xa_root(inode->i_sb, flags);
 153	if (IS_ERR(xaroot))
 154		return xaroot;
 155
 156	snprintf(namebuf, sizeof(namebuf), "%X.%X",
 157		 le32_to_cpu(INODE_PKEY(inode)->k_objectid),
 158		 inode->i_generation);
 159
 160	inode_lock_nested(d_inode(xaroot), I_MUTEX_XATTR);
 161
 162	xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
 163	if (!IS_ERR(xadir) && d_really_is_negative(xadir)) {
 164		int err = -ENODATA;
 165
 166		if (xattr_may_create(flags))
 167			err = xattr_mkdir(d_inode(xaroot), xadir, 0700);
 168		if (err) {
 169			dput(xadir);
 170			xadir = ERR_PTR(err);
 171		}
 172	}
 173
 174	inode_unlock(d_inode(xaroot));
 175	dput(xaroot);
 176	return xadir;
 177}
 178
 179/*
 180 * The following are side effects of other operations that aren't explicitly
 181 * modifying extended attributes. This includes operations such as permissions
 182 * or ownership changes, object deletions, etc.
 183 */
 184struct reiserfs_dentry_buf {
 185	struct dir_context ctx;
 186	struct dentry *xadir;
 187	int count;
 188	int err;
 189	struct dentry *dentries[8];
 190};
 191
 192static bool
 193fill_with_dentries(struct dir_context *ctx, const char *name, int namelen,
 194		   loff_t offset, u64 ino, unsigned int d_type)
 195{
 196	struct reiserfs_dentry_buf *dbuf =
 197		container_of(ctx, struct reiserfs_dentry_buf, ctx);
 198	struct dentry *dentry;
 199
 200	WARN_ON_ONCE(!inode_is_locked(d_inode(dbuf->xadir)));
 201
 202	if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
 203		return false;
 204
 205	if (name[0] == '.' && (namelen < 2 ||
 206			       (namelen == 2 && name[1] == '.')))
 207		return true;
 208
 209	dentry = lookup_one_len(name, dbuf->xadir, namelen);
 210	if (IS_ERR(dentry)) {
 211		dbuf->err = PTR_ERR(dentry);
 212		return false;
 213	} else if (d_really_is_negative(dentry)) {
 214		/* A directory entry exists, but no file? */
 215		reiserfs_error(dentry->d_sb, "xattr-20003",
 216			       "Corrupted directory: xattr %pd listed but "
 217			       "not found for file %pd.\n",
 218			       dentry, dbuf->xadir);
 219		dput(dentry);
 220		dbuf->err = -EIO;
 221		return false;
 222	}
 223
 224	dbuf->dentries[dbuf->count++] = dentry;
 225	return true;
 226}
 227
 228static void
 229cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
 230{
 231	int i;
 232
 233	for (i = 0; i < buf->count; i++)
 234		if (buf->dentries[i])
 235			dput(buf->dentries[i]);
 236}
 237
 238static int reiserfs_for_each_xattr(struct inode *inode,
 239				   int (*action)(struct dentry *, void *),
 240				   void *data)
 241{
 242	struct dentry *dir;
 243	int i, err = 0;
 244	struct reiserfs_dentry_buf buf = {
 245		.ctx.actor = fill_with_dentries,
 246	};
 247
 248	/* Skip out, an xattr has no xattrs associated with it */
 249	if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
 250		return 0;
 251
 252	dir = open_xa_dir(inode, XATTR_REPLACE);
 253	if (IS_ERR(dir)) {
 254		err = PTR_ERR(dir);
 255		goto out;
 256	} else if (d_really_is_negative(dir)) {
 257		err = 0;
 258		goto out_dir;
 259	}
 260
 261	inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
 262
 263	buf.xadir = dir;
 264	while (1) {
 265		err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
 266		if (err)
 267			break;
 268		if (buf.err) {
 269			err = buf.err;
 270			break;
 271		}
 272		if (!buf.count)
 273			break;
 274		for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) {
 275			struct dentry *dentry = buf.dentries[i];
 276
 277			if (!d_is_dir(dentry))
 278				err = action(dentry, data);
 279
 280			dput(dentry);
 281			buf.dentries[i] = NULL;
 282		}
 283		if (err)
 284			break;
 285		buf.count = 0;
 286	}
 287	inode_unlock(d_inode(dir));
 288
 289	cleanup_dentry_buf(&buf);
 290
 291	if (!err) {
 292		/*
 293		 * We start a transaction here to avoid a ABBA situation
 294		 * between the xattr root's i_mutex and the journal lock.
 295		 * This doesn't incur much additional overhead since the
 296		 * new transaction will just nest inside the
 297		 * outer transaction.
 298		 */
 299		int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
 300			     4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
 301		struct reiserfs_transaction_handle th;
 302
 303		reiserfs_write_lock(inode->i_sb);
 304		err = journal_begin(&th, inode->i_sb, blocks);
 305		reiserfs_write_unlock(inode->i_sb);
 306		if (!err) {
 307			int jerror;
 308
 309			inode_lock_nested(d_inode(dir->d_parent),
 310					  I_MUTEX_XATTR);
 311			err = action(dir, data);
 312			reiserfs_write_lock(inode->i_sb);
 313			jerror = journal_end(&th);
 314			reiserfs_write_unlock(inode->i_sb);
 315			inode_unlock(d_inode(dir->d_parent));
 316			err = jerror ?: err;
 317		}
 318	}
 319out_dir:
 320	dput(dir);
 321out:
 322	/*
 323	 * -ENODATA: this object doesn't have any xattrs
 324	 * -EOPNOTSUPP: this file system doesn't have xattrs enabled on disk.
 325	 * Neither are errors
 326	 */
 327	if (err == -ENODATA || err == -EOPNOTSUPP)
 328		err = 0;
 329	return err;
 330}
 331
 332static int delete_one_xattr(struct dentry *dentry, void *data)
 333{
 334	struct inode *dir = d_inode(dentry->d_parent);
 335
 336	/* This is the xattr dir, handle specially. */
 337	if (d_is_dir(dentry))
 338		return xattr_rmdir(dir, dentry);
 339
 340	return xattr_unlink(dir, dentry);
 341}
 342
 343static int chown_one_xattr(struct dentry *dentry, void *data)
 344{
 345	struct iattr *attrs = data;
 346	int ia_valid = attrs->ia_valid;
 347	int err;
 348
 349	/*
 350	 * We only want the ownership bits. Otherwise, we'll do
 351	 * things like change a directory to a regular file if
 352	 * ATTR_MODE is set.
 353	 */
 354	attrs->ia_valid &= (ATTR_UID|ATTR_GID);
 355	err = reiserfs_setattr(&init_user_ns, dentry, attrs);
 356	attrs->ia_valid = ia_valid;
 357
 358	return err;
 359}
 360
 361/* No i_mutex, but the inode is unconnected. */
 362int reiserfs_delete_xattrs(struct inode *inode)
 363{
 364	int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
 365
 366	if (err)
 367		reiserfs_warning(inode->i_sb, "jdm-20004",
 368				 "Couldn't delete all xattrs (%d)\n", err);
 369	return err;
 370}
 371
 372/* inode->i_mutex: down */
 373int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
 374{
 375	int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
 376
 377	if (err)
 378		reiserfs_warning(inode->i_sb, "jdm-20007",
 379				 "Couldn't chown all xattrs (%d)\n", err);
 380	return err;
 381}
 382
 383#ifdef CONFIG_REISERFS_FS_XATTR
 384/*
 385 * Returns a dentry corresponding to a specific extended attribute file
 386 * for the inode. If flags allow, the file is created. Otherwise, a
 387 * valid or negative dentry, or an error is returned.
 388 */
 389static struct dentry *xattr_lookup(struct inode *inode, const char *name,
 390				    int flags)
 391{
 392	struct dentry *xadir, *xafile;
 393	int err = 0;
 394
 395	xadir = open_xa_dir(inode, flags);
 396	if (IS_ERR(xadir))
 397		return ERR_CAST(xadir);
 398
 399	inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
 400	xafile = lookup_one_len(name, xadir, strlen(name));
 401	if (IS_ERR(xafile)) {
 402		err = PTR_ERR(xafile);
 403		goto out;
 404	}
 405
 406	if (d_really_is_positive(xafile) && (flags & XATTR_CREATE))
 407		err = -EEXIST;
 408
 409	if (d_really_is_negative(xafile)) {
 410		err = -ENODATA;
 411		if (xattr_may_create(flags))
 412			err = xattr_create(d_inode(xadir), xafile,
 413					      0700|S_IFREG);
 414	}
 415
 416	if (err)
 417		dput(xafile);
 418out:
 419	inode_unlock(d_inode(xadir));
 420	dput(xadir);
 421	if (err)
 422		return ERR_PTR(err);
 423	return xafile;
 424}
 425
 426/* Internal operations on file data */
 427static inline void reiserfs_put_page(struct page *page)
 428{
 429	kunmap(page);
 430	put_page(page);
 431}
 432
 433static struct page *reiserfs_get_page(struct inode *dir, size_t n)
 434{
 435	struct address_space *mapping = dir->i_mapping;
 436	struct page *page;
 437	/*
 438	 * We can deadlock if we try to free dentries,
 439	 * and an unlink/rmdir has just occurred - GFP_NOFS avoids this
 440	 */
 441	mapping_set_gfp_mask(mapping, GFP_NOFS);
 442	page = read_mapping_page(mapping, n >> PAGE_SHIFT, NULL);
 443	if (!IS_ERR(page))
 444		kmap(page);
 
 
 
 445	return page;
 
 
 
 
 446}
 447
 448static inline __u32 xattr_hash(const char *msg, int len)
 449{
 450	/*
 451	 * csum_partial() gives different results for little-endian and
 452	 * big endian hosts. Images created on little-endian hosts and
 453	 * mounted on big-endian hosts(and vice versa) will see csum mismatches
 454	 * when trying to fetch xattrs. Treating the hash as __wsum_t would
 455	 * lower the frequency of mismatch.  This is an endianness bug in
 456	 * reiserfs.  The return statement would result in a sparse warning. Do
 457	 * not fix the sparse warning so as to not hide a reminder of the bug.
 458	 */
 459	return csum_partial(msg, len, 0);
 460}
 461
 462int reiserfs_commit_write(struct file *f, struct page *page,
 463			  unsigned from, unsigned to);
 464
 465static void update_ctime(struct inode *inode)
 466{
 467	struct timespec64 now = current_time(inode);
 468
 469	if (inode_unhashed(inode) || !inode->i_nlink ||
 470	    timespec64_equal(&inode->i_ctime, &now))
 471		return;
 472
 473	inode->i_ctime = current_time(inode);
 474	mark_inode_dirty(inode);
 475}
 476
 477static int lookup_and_delete_xattr(struct inode *inode, const char *name)
 478{
 479	int err = 0;
 480	struct dentry *dentry, *xadir;
 481
 482	xadir = open_xa_dir(inode, XATTR_REPLACE);
 483	if (IS_ERR(xadir))
 484		return PTR_ERR(xadir);
 485
 486	inode_lock_nested(d_inode(xadir), I_MUTEX_XATTR);
 487	dentry = lookup_one_len(name, xadir, strlen(name));
 488	if (IS_ERR(dentry)) {
 489		err = PTR_ERR(dentry);
 490		goto out_dput;
 491	}
 492
 493	if (d_really_is_positive(dentry)) {
 494		err = xattr_unlink(d_inode(xadir), dentry);
 495		update_ctime(inode);
 496	}
 497
 498	dput(dentry);
 499out_dput:
 500	inode_unlock(d_inode(xadir));
 501	dput(xadir);
 502	return err;
 503}
 504
 505
 506/* Generic extended attribute operations that can be used by xa plugins */
 507
 508/*
 509 * inode->i_mutex: down
 510 */
 511int
 512reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
 513			  struct inode *inode, const char *name,
 514			  const void *buffer, size_t buffer_size, int flags)
 515{
 516	int err = 0;
 517	struct dentry *dentry;
 518	struct page *page;
 519	char *data;
 520	size_t file_pos = 0;
 521	size_t buffer_pos = 0;
 522	size_t new_size;
 523	__u32 xahash = 0;
 524
 525	if (get_inode_sd_version(inode) == STAT_DATA_V1)
 526		return -EOPNOTSUPP;
 527
 528	if (!buffer) {
 529		err = lookup_and_delete_xattr(inode, name);
 530		return err;
 531	}
 532
 533	dentry = xattr_lookup(inode, name, flags);
 534	if (IS_ERR(dentry))
 535		return PTR_ERR(dentry);
 536
 537	down_write(&REISERFS_I(inode)->i_xattr_sem);
 538
 539	xahash = xattr_hash(buffer, buffer_size);
 540	while (buffer_pos < buffer_size || buffer_pos == 0) {
 541		size_t chunk;
 542		size_t skip = 0;
 543		size_t page_offset = (file_pos & (PAGE_SIZE - 1));
 544
 545		if (buffer_size - buffer_pos > PAGE_SIZE)
 546			chunk = PAGE_SIZE;
 547		else
 548			chunk = buffer_size - buffer_pos;
 549
 550		page = reiserfs_get_page(d_inode(dentry), file_pos);
 551		if (IS_ERR(page)) {
 552			err = PTR_ERR(page);
 553			goto out_unlock;
 554		}
 555
 556		lock_page(page);
 557		data = page_address(page);
 558
 559		if (file_pos == 0) {
 560			struct reiserfs_xattr_header *rxh;
 561
 562			skip = file_pos = sizeof(struct reiserfs_xattr_header);
 563			if (chunk + skip > PAGE_SIZE)
 564				chunk = PAGE_SIZE - skip;
 565			rxh = (struct reiserfs_xattr_header *)data;
 566			rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
 567			rxh->h_hash = cpu_to_le32(xahash);
 568		}
 569
 570		reiserfs_write_lock(inode->i_sb);
 571		err = __reiserfs_write_begin(page, page_offset, chunk + skip);
 572		if (!err) {
 573			if (buffer)
 574				memcpy(data + skip, buffer + buffer_pos, chunk);
 575			err = reiserfs_commit_write(NULL, page, page_offset,
 576						    page_offset + chunk +
 577						    skip);
 578		}
 579		reiserfs_write_unlock(inode->i_sb);
 580		unlock_page(page);
 581		reiserfs_put_page(page);
 582		buffer_pos += chunk;
 583		file_pos += chunk;
 584		skip = 0;
 585		if (err || buffer_size == 0 || !buffer)
 586			break;
 587	}
 588
 589	new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
 590	if (!err && new_size < i_size_read(d_inode(dentry))) {
 591		struct iattr newattrs = {
 592			.ia_ctime = current_time(inode),
 593			.ia_size = new_size,
 594			.ia_valid = ATTR_SIZE | ATTR_CTIME,
 595		};
 596
 597		inode_lock_nested(d_inode(dentry), I_MUTEX_XATTR);
 598		inode_dio_wait(d_inode(dentry));
 599
 600		err = reiserfs_setattr(&init_user_ns, dentry, &newattrs);
 601		inode_unlock(d_inode(dentry));
 602	} else
 603		update_ctime(inode);
 604out_unlock:
 605	up_write(&REISERFS_I(inode)->i_xattr_sem);
 606	dput(dentry);
 607	return err;
 608}
 609
 610/* We need to start a transaction to maintain lock ordering */
 611int reiserfs_xattr_set(struct inode *inode, const char *name,
 612		       const void *buffer, size_t buffer_size, int flags)
 613{
 614
 615	struct reiserfs_transaction_handle th;
 616	int error, error2;
 617	size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
 618
 619	/* Check before we start a transaction and then do nothing. */
 620	if (!d_really_is_positive(REISERFS_SB(inode->i_sb)->priv_root))
 621		return -EOPNOTSUPP;
 622
 623	if (!(flags & XATTR_REPLACE))
 624		jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
 625
 626	reiserfs_write_lock(inode->i_sb);
 627	error = journal_begin(&th, inode->i_sb, jbegin_count);
 628	reiserfs_write_unlock(inode->i_sb);
 629	if (error) {
 630		return error;
 631	}
 632
 633	error = reiserfs_xattr_set_handle(&th, inode, name,
 634					  buffer, buffer_size, flags);
 635
 636	reiserfs_write_lock(inode->i_sb);
 637	error2 = journal_end(&th);
 638	reiserfs_write_unlock(inode->i_sb);
 639	if (error == 0)
 640		error = error2;
 641
 642	return error;
 643}
 644
 645/*
 646 * inode->i_mutex: down
 647 */
 648int
 649reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
 650		   size_t buffer_size)
 651{
 652	ssize_t err = 0;
 653	struct dentry *dentry;
 654	size_t isize;
 655	size_t file_pos = 0;
 656	size_t buffer_pos = 0;
 657	struct page *page;
 658	__u32 hash = 0;
 659
 660	if (name == NULL)
 661		return -EINVAL;
 662
 663	/*
 664	 * We can't have xattrs attached to v1 items since they don't have
 665	 * generation numbers
 666	 */
 667	if (get_inode_sd_version(inode) == STAT_DATA_V1)
 668		return -EOPNOTSUPP;
 669
 670	/*
 671	 * priv_root needn't be initialized during mount so allow initial
 672	 * lookups to succeed.
 673	 */
 674	if (!REISERFS_SB(inode->i_sb)->priv_root)
 675		return 0;
 676
 677	dentry = xattr_lookup(inode, name, XATTR_REPLACE);
 678	if (IS_ERR(dentry)) {
 679		err = PTR_ERR(dentry);
 680		goto out;
 681	}
 682
 683	down_read(&REISERFS_I(inode)->i_xattr_sem);
 684
 685	isize = i_size_read(d_inode(dentry));
 686
 687	/* Just return the size needed */
 688	if (buffer == NULL) {
 689		err = isize - sizeof(struct reiserfs_xattr_header);
 690		goto out_unlock;
 691	}
 692
 693	if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
 694		err = -ERANGE;
 695		goto out_unlock;
 696	}
 697
 698	while (file_pos < isize) {
 699		size_t chunk;
 700		char *data;
 701		size_t skip = 0;
 702
 703		if (isize - file_pos > PAGE_SIZE)
 704			chunk = PAGE_SIZE;
 705		else
 706			chunk = isize - file_pos;
 707
 708		page = reiserfs_get_page(d_inode(dentry), file_pos);
 709		if (IS_ERR(page)) {
 710			err = PTR_ERR(page);
 711			goto out_unlock;
 712		}
 713
 714		lock_page(page);
 715		data = page_address(page);
 716		if (file_pos == 0) {
 717			struct reiserfs_xattr_header *rxh =
 718			    (struct reiserfs_xattr_header *)data;
 719			skip = file_pos = sizeof(struct reiserfs_xattr_header);
 720			chunk -= skip;
 721			/* Magic doesn't match up.. */
 722			if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
 723				unlock_page(page);
 724				reiserfs_put_page(page);
 725				reiserfs_warning(inode->i_sb, "jdm-20001",
 726						 "Invalid magic for xattr (%s) "
 727						 "associated with %k", name,
 728						 INODE_PKEY(inode));
 729				err = -EIO;
 730				goto out_unlock;
 731			}
 732			hash = le32_to_cpu(rxh->h_hash);
 733		}
 734		memcpy(buffer + buffer_pos, data + skip, chunk);
 735		unlock_page(page);
 736		reiserfs_put_page(page);
 737		file_pos += chunk;
 738		buffer_pos += chunk;
 739		skip = 0;
 740	}
 741	err = isize - sizeof(struct reiserfs_xattr_header);
 742
 743	if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
 744	    hash) {
 745		reiserfs_warning(inode->i_sb, "jdm-20002",
 746				 "Invalid hash for xattr (%s) associated "
 747				 "with %k", name, INODE_PKEY(inode));
 748		err = -EIO;
 749	}
 750
 751out_unlock:
 752	up_read(&REISERFS_I(inode)->i_xattr_sem);
 753	dput(dentry);
 754
 755out:
 756	return err;
 757}
 758
 759/*
 760 * In order to implement different sets of xattr operations for each xattr
 761 * prefix with the generic xattr API, a filesystem should create a
 762 * null-terminated array of struct xattr_handler (one for each prefix) and
 763 * hang a pointer to it off of the s_xattr field of the superblock.
 764 *
 765 * The generic_fooxattr() functions will use this list to dispatch xattr
 766 * operations to the correct xattr_handler.
 767 */
 768#define for_each_xattr_handler(handlers, handler)		\
 769		for ((handler) = *(handlers)++;			\
 770			(handler) != NULL;			\
 771			(handler) = *(handlers)++)
 772
 773/* This is the implementation for the xattr plugin infrastructure */
 774static inline const struct xattr_handler *
 775find_xattr_handler_prefix(const struct xattr_handler **handlers,
 776			   const char *name)
 777{
 778	const struct xattr_handler *xah;
 779
 780	if (!handlers)
 781		return NULL;
 782
 783	for_each_xattr_handler(handlers, xah) {
 784		const char *prefix = xattr_prefix(xah);
 785		if (strncmp(prefix, name, strlen(prefix)) == 0)
 786			break;
 787	}
 788
 789	return xah;
 790}
 791
 792struct listxattr_buf {
 793	struct dir_context ctx;
 794	size_t size;
 795	size_t pos;
 796	char *buf;
 797	struct dentry *dentry;
 798};
 799
 800static bool listxattr_filler(struct dir_context *ctx, const char *name,
 801			    int namelen, loff_t offset, u64 ino,
 802			    unsigned int d_type)
 803{
 804	struct listxattr_buf *b =
 805		container_of(ctx, struct listxattr_buf, ctx);
 806	size_t size;
 807
 808	if (name[0] != '.' ||
 809	    (namelen != 1 && (name[1] != '.' || namelen != 2))) {
 810		const struct xattr_handler *handler;
 811
 812		handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
 813						    name);
 814		if (!handler /* Unsupported xattr name */ ||
 815		    (handler->list && !handler->list(b->dentry)))
 816			return true;
 817		size = namelen + 1;
 818		if (b->buf) {
 819			if (b->pos + size > b->size) {
 820				b->pos = -ERANGE;
 821				return false;
 822			}
 823			memcpy(b->buf + b->pos, name, namelen);
 824			b->buf[b->pos + namelen] = 0;
 825		}
 826		b->pos += size;
 827	}
 828	return true;
 829}
 830
 831/*
 832 * Inode operation listxattr()
 833 *
 834 * We totally ignore the generic listxattr here because it would be stupid
 835 * not to. Since the xattrs are organized in a directory, we can just
 836 * readdir to find them.
 837 */
 838ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
 839{
 840	struct dentry *dir;
 841	int err = 0;
 842	struct listxattr_buf buf = {
 843		.ctx.actor = listxattr_filler,
 844		.dentry = dentry,
 845		.buf = buffer,
 846		.size = buffer ? size : 0,
 847	};
 848
 849	if (d_really_is_negative(dentry))
 850		return -EINVAL;
 851
 852	if (get_inode_sd_version(d_inode(dentry)) == STAT_DATA_V1)
 
 853		return -EOPNOTSUPP;
 854
 855	dir = open_xa_dir(d_inode(dentry), XATTR_REPLACE);
 856	if (IS_ERR(dir)) {
 857		err = PTR_ERR(dir);
 858		if (err == -ENODATA)
 859			err = 0;  /* Not an error if there aren't any xattrs */
 860		goto out;
 861	}
 862
 863	inode_lock_nested(d_inode(dir), I_MUTEX_XATTR);
 864	err = reiserfs_readdir_inode(d_inode(dir), &buf.ctx);
 865	inode_unlock(d_inode(dir));
 866
 867	if (!err)
 868		err = buf.pos;
 869
 870	dput(dir);
 871out:
 872	return err;
 873}
 874
 875static int create_privroot(struct dentry *dentry)
 876{
 877	int err;
 878	struct inode *inode = d_inode(dentry->d_parent);
 879
 880	WARN_ON_ONCE(!inode_is_locked(inode));
 881
 882	err = xattr_mkdir(inode, dentry, 0700);
 883	if (err || d_really_is_negative(dentry)) {
 884		reiserfs_warning(dentry->d_sb, "jdm-20006",
 885				 "xattrs/ACLs enabled and couldn't "
 886				 "find/create .reiserfs_priv. "
 887				 "Failing mount.");
 888		return -EOPNOTSUPP;
 889	}
 890
 891	d_inode(dentry)->i_flags |= S_PRIVATE;
 892	d_inode(dentry)->i_opflags &= ~IOP_XATTR;
 893	reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
 894		      "storage.\n", PRIVROOT_NAME);
 895
 896	return 0;
 897}
 898
 899#else
 900int __init reiserfs_xattr_register_handlers(void) { return 0; }
 901void reiserfs_xattr_unregister_handlers(void) {}
 902static int create_privroot(struct dentry *dentry) { return 0; }
 903#endif
 904
 905/* Actual operations that are exported to VFS-land */
 906const struct xattr_handler *reiserfs_xattr_handlers[] = {
 907#ifdef CONFIG_REISERFS_FS_XATTR
 908	&reiserfs_xattr_user_handler,
 909	&reiserfs_xattr_trusted_handler,
 910#endif
 911#ifdef CONFIG_REISERFS_FS_SECURITY
 912	&reiserfs_xattr_security_handler,
 913#endif
 914#ifdef CONFIG_REISERFS_FS_POSIX_ACL
 915	&posix_acl_access_xattr_handler,
 916	&posix_acl_default_xattr_handler,
 917#endif
 918	NULL
 919};
 920
 921static int xattr_mount_check(struct super_block *s)
 922{
 923	/*
 924	 * We need generation numbers to ensure that the oid mapping is correct
 925	 * v3.5 filesystems don't have them.
 926	 */
 927	if (old_format_only(s)) {
 928		if (reiserfs_xattrs_optional(s)) {
 929			/*
 930			 * Old format filesystem, but optional xattrs have
 931			 * been enabled. Error out.
 932			 */
 933			reiserfs_warning(s, "jdm-2005",
 934					 "xattrs/ACLs not supported "
 935					 "on pre-v3.6 format filesystems. "
 936					 "Failing mount.");
 937			return -EOPNOTSUPP;
 938		}
 939	}
 940
 941	return 0;
 942}
 943
 944int reiserfs_permission(struct user_namespace *mnt_userns, struct inode *inode,
 945			int mask)
 946{
 947	/*
 948	 * We don't do permission checks on the internal objects.
 949	 * Permissions are determined by the "owning" object.
 950	 */
 951	if (IS_PRIVATE(inode))
 952		return 0;
 953
 954	return generic_permission(&init_user_ns, inode, mask);
 955}
 956
 957static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
 958{
 959	return -EPERM;
 960}
 961
 962static const struct dentry_operations xattr_lookup_poison_ops = {
 963	.d_revalidate = xattr_hide_revalidate,
 964};
 965
 966int reiserfs_lookup_privroot(struct super_block *s)
 967{
 968	struct dentry *dentry;
 969	int err = 0;
 970
 971	/* If we don't have the privroot located yet - go find it */
 972	inode_lock(d_inode(s->s_root));
 973	dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
 974				strlen(PRIVROOT_NAME));
 975	if (!IS_ERR(dentry)) {
 976		REISERFS_SB(s)->priv_root = dentry;
 977		d_set_d_op(dentry, &xattr_lookup_poison_ops);
 978		if (d_really_is_positive(dentry)) {
 979			d_inode(dentry)->i_flags |= S_PRIVATE;
 980			d_inode(dentry)->i_opflags &= ~IOP_XATTR;
 981		}
 982	} else
 983		err = PTR_ERR(dentry);
 984	inode_unlock(d_inode(s->s_root));
 985
 986	return err;
 987}
 988
 989/*
 990 * We need to take a copy of the mount flags since things like
 991 * SB_RDONLY don't get set until *after* we're called.
 992 * mount_flags != mount_options
 993 */
 994int reiserfs_xattr_init(struct super_block *s, int mount_flags)
 995{
 996	int err = 0;
 997	struct dentry *privroot = REISERFS_SB(s)->priv_root;
 998
 999	err = xattr_mount_check(s);
1000	if (err)
1001		goto error;
1002
1003	if (d_really_is_negative(privroot) && !(mount_flags & SB_RDONLY)) {
1004		inode_lock(d_inode(s->s_root));
1005		err = create_privroot(REISERFS_SB(s)->priv_root);
1006		inode_unlock(d_inode(s->s_root));
1007	}
1008
1009	if (d_really_is_positive(privroot)) {
 
1010		inode_lock(d_inode(privroot));
1011		if (!REISERFS_SB(s)->xattr_root) {
1012			struct dentry *dentry;
1013
1014			dentry = lookup_one_len(XAROOT_NAME, privroot,
1015						strlen(XAROOT_NAME));
1016			if (!IS_ERR(dentry))
1017				REISERFS_SB(s)->xattr_root = dentry;
1018			else
1019				err = PTR_ERR(dentry);
1020		}
1021		inode_unlock(d_inode(privroot));
1022	}
1023
1024error:
1025	if (err) {
1026		clear_bit(REISERFS_XATTRS_USER, &REISERFS_SB(s)->s_mount_opt);
1027		clear_bit(REISERFS_POSIXACL, &REISERFS_SB(s)->s_mount_opt);
1028	}
1029
1030	/* The super_block SB_POSIXACL must mirror the (no)acl mount option. */
1031	if (reiserfs_posixacl(s))
1032		s->s_flags |= SB_POSIXACL;
1033	else
1034		s->s_flags &= ~SB_POSIXACL;
1035
1036	return err;
1037}