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authorDarrick J. Wong <djwong@us.ibm.com>2012-04-30 02:43:10 +0400
committerTheodore Ts'o <tytso@mit.edu>2012-04-30 02:43:10 +0400
commitcc8e94fd126ab2d2e4bcb1b65c7316196f0cec8c (patch)
tree1e9e6fa98d5f7dc2e71f615cb3de556a782d577e /fs/ext4
parentb0336e8d2108e6302aecaadd17c6c0bd686da22d (diff)
downloadlinux-cc8e94fd126ab2d2e4bcb1b65c7316196f0cec8c.tar.xz
ext4: Calculate and verify checksums of extended attribute blocks
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>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/xattr.c92
1 files changed, 77 insertions, 15 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index e88748e55c0f..e56c9ed7d6e3 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -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)
{
@@ -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
@@ -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);
@@ -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;
@@ -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);
@@ -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;
@@ -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;
@@ -796,9 +858,9 @@ inserted:
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;
}
@@ -855,8 +917,8 @@ getblk_failed:
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;
}
@@ -1193,7 +1255,7 @@ retry:
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;