linux/fs/hfsplus/extents.c
Jouni Roivas c3187cf322 hfsplus: prevent corruption in shrinking truncate
I believe there are some issues introduced by commit 31651c6071
("hfsplus: avoid deadlock on file truncation")

HFS+ has extent records which always contains 8 extents.  In case the
first extent record in catalog file gets full, new ones are allocated from
extents overflow file.

In case shrinking truncate happens to middle of an extent record which
locates in extents overflow file, the logic in hfsplus_file_truncate() was
changed so that call to hfs_brec_remove() is not guarded any more.

Right action would be just freeing the extents that exceed the new size
inside extent record by calling hfsplus_free_extents(), and then check if
the whole extent record should be removed.  However since the guard
(blk_cnt > start) is now after the call to hfs_brec_remove(), this has
unfortunate effect that the last matching extent record is removed
unconditionally.

To reproduce this issue, create a file which has at least 10 extents, and
then perform shrinking truncate into middle of the last extent record, so
that the number of remaining extents is not under or divisible by 8.  This
causes the last extent record (8 extents) to be removed totally instead of
truncating into middle of it.  Thus this causes corruption, and lost data.

Fix for this is simply checking if the new truncated end is below the
start of this extent record, making it safe to remove the full extent
record.  However call to hfs_brec_remove() can't be moved to it's previous
place since we're dropping ->tree_lock and it can cause a race condition
and the cached info being invalidated possibly corrupting the node data.

Another issue is related to this one.  When entering into the block
(blk_cnt > start) we are not holding the ->tree_lock.  We break out from
the loop not holding the lock, but hfs_find_exit() does unlock it.  Not
sure if it's possible for someone else to take the lock under our feet,
but it can cause hard to debug errors and premature unlocking.  Even if
there's no real risk of it, the locking should still always be kept in
balance.  Thus taking the lock now just before the check.

Link: https://lkml.kernel.org/r/20210429165139.3082828-1-jouni.roivas@tuxera.com
Fixes: 31651c6071 ("hfsplus: avoid deadlock on file truncation")
Signed-off-by: Jouni Roivas <jouni.roivas@tuxera.com>
Reviewed-by: Anton Altaparmakov <anton@tuxera.com>
Cc: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Cc: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-14 19:41:32 -07:00

629 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/hfsplus/extents.c
*
* Copyright (C) 2001
* Brad Boyer (flar@allandria.com)
* (C) 2003 Ardis Technologies <roman@ardistech.com>
*
* Handling of Extents both in catalog and extents overflow trees
*/
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include "hfsplus_fs.h"
#include "hfsplus_raw.h"
/* Compare two extents keys, returns 0 on same, pos/neg for difference */
int hfsplus_ext_cmp_key(const hfsplus_btree_key *k1,
const hfsplus_btree_key *k2)
{
__be32 k1id, k2id;
__be32 k1s, k2s;
k1id = k1->ext.cnid;
k2id = k2->ext.cnid;
if (k1id != k2id)
return be32_to_cpu(k1id) < be32_to_cpu(k2id) ? -1 : 1;
if (k1->ext.fork_type != k2->ext.fork_type)
return k1->ext.fork_type < k2->ext.fork_type ? -1 : 1;
k1s = k1->ext.start_block;
k2s = k2->ext.start_block;
if (k1s == k2s)
return 0;
return be32_to_cpu(k1s) < be32_to_cpu(k2s) ? -1 : 1;
}
static void hfsplus_ext_build_key(hfsplus_btree_key *key, u32 cnid,
u32 block, u8 type)
{
key->key_len = cpu_to_be16(HFSPLUS_EXT_KEYLEN - 2);
key->ext.cnid = cpu_to_be32(cnid);
key->ext.start_block = cpu_to_be32(block);
key->ext.fork_type = type;
key->ext.pad = 0;
}
static u32 hfsplus_ext_find_block(struct hfsplus_extent *ext, u32 off)
{
int i;
u32 count;
for (i = 0; i < 8; ext++, i++) {
count = be32_to_cpu(ext->block_count);
if (off < count)
return be32_to_cpu(ext->start_block) + off;
off -= count;
}
/* panic? */
return 0;
}
static int hfsplus_ext_block_count(struct hfsplus_extent *ext)
{
int i;
u32 count = 0;
for (i = 0; i < 8; ext++, i++)
count += be32_to_cpu(ext->block_count);
return count;
}
static u32 hfsplus_ext_lastblock(struct hfsplus_extent *ext)
{
int i;
ext += 7;
for (i = 0; i < 7; ext--, i++)
if (ext->block_count)
break;
return be32_to_cpu(ext->start_block) + be32_to_cpu(ext->block_count);
}
static int __hfsplus_ext_write_extent(struct inode *inode,
struct hfs_find_data *fd)
{
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
int res;
WARN_ON(!mutex_is_locked(&hip->extents_lock));
hfsplus_ext_build_key(fd->search_key, inode->i_ino, hip->cached_start,
HFSPLUS_IS_RSRC(inode) ?
HFSPLUS_TYPE_RSRC : HFSPLUS_TYPE_DATA);
res = hfs_brec_find(fd, hfs_find_rec_by_key);
if (hip->extent_state & HFSPLUS_EXT_NEW) {
if (res != -ENOENT)
return res;
/* Fail early and avoid ENOSPC during the btree operation */
res = hfs_bmap_reserve(fd->tree, fd->tree->depth + 1);
if (res)
return res;
hfs_brec_insert(fd, hip->cached_extents,
sizeof(hfsplus_extent_rec));
hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
} else {
if (res)
return res;
hfs_bnode_write(fd->bnode, hip->cached_extents,
fd->entryoffset, fd->entrylength);
hip->extent_state &= ~HFSPLUS_EXT_DIRTY;
}
/*
* We can't just use hfsplus_mark_inode_dirty here, because we
* also get called from hfsplus_write_inode, which should not
* redirty the inode. Instead the callers have to be careful
* to explicily mark the inode dirty, too.
*/
set_bit(HFSPLUS_I_EXT_DIRTY, &hip->flags);
return 0;
}
static int hfsplus_ext_write_extent_locked(struct inode *inode)
{
int res = 0;
if (HFSPLUS_I(inode)->extent_state & HFSPLUS_EXT_DIRTY) {
struct hfs_find_data fd;
res = hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
if (res)
return res;
res = __hfsplus_ext_write_extent(inode, &fd);
hfs_find_exit(&fd);
}
return res;
}
int hfsplus_ext_write_extent(struct inode *inode)
{
int res;
mutex_lock(&HFSPLUS_I(inode)->extents_lock);
res = hfsplus_ext_write_extent_locked(inode);
mutex_unlock(&HFSPLUS_I(inode)->extents_lock);
return res;
}
static inline int __hfsplus_ext_read_extent(struct hfs_find_data *fd,
struct hfsplus_extent *extent,
u32 cnid, u32 block, u8 type)
{
int res;
hfsplus_ext_build_key(fd->search_key, cnid, block, type);
fd->key->ext.cnid = 0;
res = hfs_brec_find(fd, hfs_find_rec_by_key);
if (res && res != -ENOENT)
return res;
if (fd->key->ext.cnid != fd->search_key->ext.cnid ||
fd->key->ext.fork_type != fd->search_key->ext.fork_type)
return -ENOENT;
if (fd->entrylength != sizeof(hfsplus_extent_rec))
return -EIO;
hfs_bnode_read(fd->bnode, extent, fd->entryoffset,
sizeof(hfsplus_extent_rec));
return 0;
}
static inline int __hfsplus_ext_cache_extent(struct hfs_find_data *fd,
struct inode *inode, u32 block)
{
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
int res;
WARN_ON(!mutex_is_locked(&hip->extents_lock));
if (hip->extent_state & HFSPLUS_EXT_DIRTY) {
res = __hfsplus_ext_write_extent(inode, fd);
if (res)
return res;
}
res = __hfsplus_ext_read_extent(fd, hip->cached_extents, inode->i_ino,
block, HFSPLUS_IS_RSRC(inode) ?
HFSPLUS_TYPE_RSRC :
HFSPLUS_TYPE_DATA);
if (!res) {
hip->cached_start = be32_to_cpu(fd->key->ext.start_block);
hip->cached_blocks =
hfsplus_ext_block_count(hip->cached_extents);
} else {
hip->cached_start = hip->cached_blocks = 0;
hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
}
return res;
}
static int hfsplus_ext_read_extent(struct inode *inode, u32 block)
{
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
struct hfs_find_data fd;
int res;
if (block >= hip->cached_start &&
block < hip->cached_start + hip->cached_blocks)
return 0;
res = hfs_find_init(HFSPLUS_SB(inode->i_sb)->ext_tree, &fd);
if (!res) {
res = __hfsplus_ext_cache_extent(&fd, inode, block);
hfs_find_exit(&fd);
}
return res;
}
/* Get a block at iblock for inode, possibly allocating if create */
int hfsplus_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
struct super_block *sb = inode->i_sb;
struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
int res = -EIO;
u32 ablock, dblock, mask;
sector_t sector;
int was_dirty = 0;
/* Convert inode block to disk allocation block */
ablock = iblock >> sbi->fs_shift;
if (iblock >= hip->fs_blocks) {
if (!create)
return 0;
if (iblock > hip->fs_blocks)
return -EIO;
if (ablock >= hip->alloc_blocks) {
res = hfsplus_file_extend(inode, false);
if (res)
return res;
}
} else
create = 0;
if (ablock < hip->first_blocks) {
dblock = hfsplus_ext_find_block(hip->first_extents, ablock);
goto done;
}
if (inode->i_ino == HFSPLUS_EXT_CNID)
return -EIO;
mutex_lock(&hip->extents_lock);
/*
* hfsplus_ext_read_extent will write out a cached extent into
* the extents btree. In that case we may have to mark the inode
* dirty even for a pure read of an extent here.
*/
was_dirty = (hip->extent_state & HFSPLUS_EXT_DIRTY);
res = hfsplus_ext_read_extent(inode, ablock);
if (res) {
mutex_unlock(&hip->extents_lock);
return -EIO;
}
dblock = hfsplus_ext_find_block(hip->cached_extents,
ablock - hip->cached_start);
mutex_unlock(&hip->extents_lock);
done:
hfs_dbg(EXTENT, "get_block(%lu): %llu - %u\n",
inode->i_ino, (long long)iblock, dblock);
mask = (1 << sbi->fs_shift) - 1;
sector = ((sector_t)dblock << sbi->fs_shift) +
sbi->blockoffset + (iblock & mask);
map_bh(bh_result, sb, sector);
if (create) {
set_buffer_new(bh_result);
hip->phys_size += sb->s_blocksize;
hip->fs_blocks++;
inode_add_bytes(inode, sb->s_blocksize);
}
if (create || was_dirty)
mark_inode_dirty(inode);
return 0;
}
static void hfsplus_dump_extent(struct hfsplus_extent *extent)
{
int i;
hfs_dbg(EXTENT, " ");
for (i = 0; i < 8; i++)
hfs_dbg_cont(EXTENT, " %u:%u",
be32_to_cpu(extent[i].start_block),
be32_to_cpu(extent[i].block_count));
hfs_dbg_cont(EXTENT, "\n");
}
static int hfsplus_add_extent(struct hfsplus_extent *extent, u32 offset,
u32 alloc_block, u32 block_count)
{
u32 count, start;
int i;
hfsplus_dump_extent(extent);
for (i = 0; i < 8; extent++, i++) {
count = be32_to_cpu(extent->block_count);
if (offset == count) {
start = be32_to_cpu(extent->start_block);
if (alloc_block != start + count) {
if (++i >= 8)
return -ENOSPC;
extent++;
extent->start_block = cpu_to_be32(alloc_block);
} else
block_count += count;
extent->block_count = cpu_to_be32(block_count);
return 0;
} else if (offset < count)
break;
offset -= count;
}
/* panic? */
return -EIO;
}
static int hfsplus_free_extents(struct super_block *sb,
struct hfsplus_extent *extent,
u32 offset, u32 block_nr)
{
u32 count, start;
int i;
int err = 0;
/* Mapping the allocation file may lock the extent tree */
WARN_ON(mutex_is_locked(&HFSPLUS_SB(sb)->ext_tree->tree_lock));
hfsplus_dump_extent(extent);
for (i = 0; i < 8; extent++, i++) {
count = be32_to_cpu(extent->block_count);
if (offset == count)
goto found;
else if (offset < count)
break;
offset -= count;
}
/* panic? */
return -EIO;
found:
for (;;) {
start = be32_to_cpu(extent->start_block);
if (count <= block_nr) {
err = hfsplus_block_free(sb, start, count);
if (err) {
pr_err("can't free extent\n");
hfs_dbg(EXTENT, " start: %u count: %u\n",
start, count);
}
extent->block_count = 0;
extent->start_block = 0;
block_nr -= count;
} else {
count -= block_nr;
err = hfsplus_block_free(sb, start + count, block_nr);
if (err) {
pr_err("can't free extent\n");
hfs_dbg(EXTENT, " start: %u count: %u\n",
start, count);
}
extent->block_count = cpu_to_be32(count);
block_nr = 0;
}
if (!block_nr || !i) {
/*
* Try to free all extents and
* return only last error
*/
return err;
}
i--;
extent--;
count = be32_to_cpu(extent->block_count);
}
}
int hfsplus_free_fork(struct super_block *sb, u32 cnid,
struct hfsplus_fork_raw *fork, int type)
{
struct hfs_find_data fd;
hfsplus_extent_rec ext_entry;
u32 total_blocks, blocks, start;
int res, i;
total_blocks = be32_to_cpu(fork->total_blocks);
if (!total_blocks)
return 0;
blocks = 0;
for (i = 0; i < 8; i++)
blocks += be32_to_cpu(fork->extents[i].block_count);
res = hfsplus_free_extents(sb, fork->extents, blocks, blocks);
if (res)
return res;
if (total_blocks == blocks)
return 0;
res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
if (res)
return res;
do {
res = __hfsplus_ext_read_extent(&fd, ext_entry, cnid,
total_blocks, type);
if (res)
break;
start = be32_to_cpu(fd.key->ext.start_block);
hfs_brec_remove(&fd);
mutex_unlock(&fd.tree->tree_lock);
hfsplus_free_extents(sb, ext_entry, total_blocks - start,
total_blocks);
total_blocks = start;
mutex_lock(&fd.tree->tree_lock);
} while (total_blocks > blocks);
hfs_find_exit(&fd);
return res;
}
int hfsplus_file_extend(struct inode *inode, bool zeroout)
{
struct super_block *sb = inode->i_sb;
struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
u32 start, len, goal;
int res;
if (sbi->alloc_file->i_size * 8 <
sbi->total_blocks - sbi->free_blocks + 8) {
/* extend alloc file */
pr_err("extend alloc file! (%llu,%u,%u)\n",
sbi->alloc_file->i_size * 8,
sbi->total_blocks, sbi->free_blocks);
return -ENOSPC;
}
mutex_lock(&hip->extents_lock);
if (hip->alloc_blocks == hip->first_blocks)
goal = hfsplus_ext_lastblock(hip->first_extents);
else {
res = hfsplus_ext_read_extent(inode, hip->alloc_blocks);
if (res)
goto out;
goal = hfsplus_ext_lastblock(hip->cached_extents);
}
len = hip->clump_blocks;
start = hfsplus_block_allocate(sb, sbi->total_blocks, goal, &len);
if (start >= sbi->total_blocks) {
start = hfsplus_block_allocate(sb, goal, 0, &len);
if (start >= goal) {
res = -ENOSPC;
goto out;
}
}
if (zeroout) {
res = sb_issue_zeroout(sb, start, len, GFP_NOFS);
if (res)
goto out;
}
hfs_dbg(EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);
if (hip->alloc_blocks <= hip->first_blocks) {
if (!hip->first_blocks) {
hfs_dbg(EXTENT, "first extents\n");
/* no extents yet */
hip->first_extents[0].start_block = cpu_to_be32(start);
hip->first_extents[0].block_count = cpu_to_be32(len);
res = 0;
} else {
/* try to append to extents in inode */
res = hfsplus_add_extent(hip->first_extents,
hip->alloc_blocks,
start, len);
if (res == -ENOSPC)
goto insert_extent;
}
if (!res) {
hfsplus_dump_extent(hip->first_extents);
hip->first_blocks += len;
}
} else {
res = hfsplus_add_extent(hip->cached_extents,
hip->alloc_blocks - hip->cached_start,
start, len);
if (!res) {
hfsplus_dump_extent(hip->cached_extents);
hip->extent_state |= HFSPLUS_EXT_DIRTY;
hip->cached_blocks += len;
} else if (res == -ENOSPC)
goto insert_extent;
}
out:
if (!res) {
hip->alloc_blocks += len;
mutex_unlock(&hip->extents_lock);
hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
return 0;
}
mutex_unlock(&hip->extents_lock);
return res;
insert_extent:
hfs_dbg(EXTENT, "insert new extent\n");
res = hfsplus_ext_write_extent_locked(inode);
if (res)
goto out;
memset(hip->cached_extents, 0, sizeof(hfsplus_extent_rec));
hip->cached_extents[0].start_block = cpu_to_be32(start);
hip->cached_extents[0].block_count = cpu_to_be32(len);
hfsplus_dump_extent(hip->cached_extents);
hip->extent_state |= HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW;
hip->cached_start = hip->alloc_blocks;
hip->cached_blocks = len;
res = 0;
goto out;
}
void hfsplus_file_truncate(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
struct hfs_find_data fd;
u32 alloc_cnt, blk_cnt, start;
int res;
hfs_dbg(INODE, "truncate: %lu, %llu -> %llu\n",
inode->i_ino, (long long)hip->phys_size, inode->i_size);
if (inode->i_size > hip->phys_size) {
struct address_space *mapping = inode->i_mapping;
struct page *page;
void *fsdata;
loff_t size = inode->i_size;
res = pagecache_write_begin(NULL, mapping, size, 0, 0,
&page, &fsdata);
if (res)
return;
res = pagecache_write_end(NULL, mapping, size,
0, 0, page, fsdata);
if (res < 0)
return;
mark_inode_dirty(inode);
return;
} else if (inode->i_size == hip->phys_size)
return;
blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >>
HFSPLUS_SB(sb)->alloc_blksz_shift;
mutex_lock(&hip->extents_lock);
alloc_cnt = hip->alloc_blocks;
if (blk_cnt == alloc_cnt)
goto out_unlock;
res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
if (res) {
mutex_unlock(&hip->extents_lock);
/* XXX: We lack error handling of hfsplus_file_truncate() */
return;
}
while (1) {
if (alloc_cnt == hip->first_blocks) {
mutex_unlock(&fd.tree->tree_lock);
hfsplus_free_extents(sb, hip->first_extents,
alloc_cnt, alloc_cnt - blk_cnt);
hfsplus_dump_extent(hip->first_extents);
hip->first_blocks = blk_cnt;
mutex_lock(&fd.tree->tree_lock);
break;
}
res = __hfsplus_ext_cache_extent(&fd, inode, alloc_cnt);
if (res)
break;
start = hip->cached_start;
if (blk_cnt <= start)
hfs_brec_remove(&fd);
mutex_unlock(&fd.tree->tree_lock);
hfsplus_free_extents(sb, hip->cached_extents,
alloc_cnt - start, alloc_cnt - blk_cnt);
hfsplus_dump_extent(hip->cached_extents);
mutex_lock(&fd.tree->tree_lock);
if (blk_cnt > start) {
hip->extent_state |= HFSPLUS_EXT_DIRTY;
break;
}
alloc_cnt = start;
hip->cached_start = hip->cached_blocks = 0;
hip->extent_state &= ~(HFSPLUS_EXT_DIRTY | HFSPLUS_EXT_NEW);
}
hfs_find_exit(&fd);
hip->alloc_blocks = blk_cnt;
out_unlock:
mutex_unlock(&hip->extents_lock);
hip->phys_size = inode->i_size;
hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >>
sb->s_blocksize_bits;
inode_set_bytes(inode, hip->fs_blocks << sb->s_blocksize_bits);
hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY);
}