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ext4: Calculate and verify checksums of extended attribute blocks
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Calculate and verify the checksums of extended attribute blocks.  This
only applies to separate EA blocks that are pointed to by
inode->i_file_acl (i.e.  external EA blocks); the checksum lives in
the EA header.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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Darrick J. Wong authored and Theodore Ts'o committed Apr 29, 2012
1 parent b0336e8 commit cc8e94f
Showing 1 changed file with 77 additions and 15 deletions.
92 changes: 77 additions & 15 deletions fs/ext4/xattr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,58 @@ const struct xattr_handler *ext4_xattr_handlers[] = {
NULL
};

static __le32 ext4_xattr_block_csum(struct inode *inode,
sector_t block_nr,
struct ext4_xattr_header *hdr)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
__u32 csum, old;

old = hdr->h_checksum;
hdr->h_checksum = 0;
if (le32_to_cpu(hdr->h_refcount) != 1) {
block_nr = cpu_to_le64(block_nr);
csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&block_nr,
sizeof(block_nr));
} else
csum = ei->i_csum_seed;
csum = ext4_chksum(sbi, csum, (__u8 *)hdr,
EXT4_BLOCK_SIZE(inode->i_sb));
hdr->h_checksum = old;
return cpu_to_le32(csum);
}

static int ext4_xattr_block_csum_verify(struct inode *inode,
sector_t block_nr,
struct ext4_xattr_header *hdr)
{
if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
(hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
return 0;
return 1;
}

static void ext4_xattr_block_csum_set(struct inode *inode,
sector_t block_nr,
struct ext4_xattr_header *hdr)
{
if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
return;

hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
}

static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
struct inode *inode,
struct buffer_head *bh)
{
ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
return ext4_handle_dirty_metadata(handle, inode, bh);
}

static inline const struct xattr_handler *
ext4_xattr_handler(int name_index)
{
Expand Down Expand Up @@ -156,12 +208,22 @@ ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
}

static inline int
ext4_xattr_check_block(struct buffer_head *bh)
ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
{
int error;

if (buffer_verified(bh))
return 0;

if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
BHDR(bh)->h_blocks != cpu_to_le32(1))
return -EIO;
return ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
return -EIO;
error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
if (!error)
set_buffer_verified(bh);
return error;
}

static inline int
Expand Down Expand Up @@ -224,7 +286,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
goto cleanup;
ea_bdebug(bh, "b_count=%d, refcount=%d",
atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
if (ext4_xattr_check_block(bh)) {
if (ext4_xattr_check_block(inode, bh)) {
bad_block:
EXT4_ERROR_INODE(inode, "bad block %llu",
EXT4_I(inode)->i_file_acl);
Expand Down Expand Up @@ -369,7 +431,7 @@ ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
goto cleanup;
ea_bdebug(bh, "b_count=%d, refcount=%d",
atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));
if (ext4_xattr_check_block(bh)) {
if (ext4_xattr_check_block(inode, bh)) {
EXT4_ERROR_INODE(inode, "bad block %llu",
EXT4_I(inode)->i_file_acl);
error = -EIO;
Expand Down Expand Up @@ -492,7 +554,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
if (ce)
mb_cache_entry_release(ce);
unlock_buffer(bh);
error = ext4_handle_dirty_metadata(handle, inode, bh);
error = ext4_handle_dirty_xattr_block(handle, inode, bh);
if (IS_SYNC(inode))
ext4_handle_sync(handle);
dquot_free_block(inode, 1);
Expand Down Expand Up @@ -662,7 +724,7 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
atomic_read(&(bs->bh->b_count)),
le32_to_cpu(BHDR(bs->bh)->h_refcount));
if (ext4_xattr_check_block(bs->bh)) {
if (ext4_xattr_check_block(inode, bs->bh)) {
EXT4_ERROR_INODE(inode, "bad block %llu",
EXT4_I(inode)->i_file_acl);
error = -EIO;
Expand Down Expand Up @@ -725,9 +787,9 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
if (error == -EIO)
goto bad_block;
if (!error)
error = ext4_handle_dirty_metadata(handle,
inode,
bs->bh);
error = ext4_handle_dirty_xattr_block(handle,
inode,
bs->bh);
if (error)
goto cleanup;
goto inserted;
Expand Down Expand Up @@ -796,9 +858,9 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
ea_bdebug(new_bh, "reusing; refcount now=%d",
le32_to_cpu(BHDR(new_bh)->h_refcount));
unlock_buffer(new_bh);
error = ext4_handle_dirty_metadata(handle,
inode,
new_bh);
error = ext4_handle_dirty_xattr_block(handle,
inode,
new_bh);
if (error)
goto cleanup_dquot;
}
Expand Down Expand Up @@ -855,8 +917,8 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
set_buffer_uptodate(new_bh);
unlock_buffer(new_bh);
ext4_xattr_cache_insert(new_bh);
error = ext4_handle_dirty_metadata(handle,
inode, new_bh);
error = ext4_handle_dirty_xattr_block(handle,
inode, new_bh);
if (error)
goto cleanup;
}
Expand Down Expand Up @@ -1193,7 +1255,7 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
error = -EIO;
if (!bh)
goto cleanup;
if (ext4_xattr_check_block(bh)) {
if (ext4_xattr_check_block(inode, bh)) {
EXT4_ERROR_INODE(inode, "bad block %llu",
EXT4_I(inode)->i_file_acl);
error = -EIO;
Expand Down

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