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    Subject[PATCH 10/23] ext4: Calculate and verify checksums for htree nodes
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    Date
    Calculate and verify the checksum for directory index tree (htree) node blocks.
    The checksum is stored in the last 4 bytes of the htree block and requires the
    dx_entry array to stop 1 dx_entry short of the end of the block.

    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---
    fs/ext4/namei.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
    1 files changed, 156 insertions(+), 4 deletions(-)


    diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
    index e62e517..064ae7c 100644
    --- a/fs/ext4/namei.c
    +++ b/fs/ext4/namei.c
    @@ -188,6 +188,121 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
    static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
    struct inode *inode);

    +/* checksumming functions */
    +static struct dx_countlimit *get_dx_countlimit(struct inode *inode,
    + struct ext4_dir_entry *dirent,
    + int *offset)
    +{
    + struct ext4_dir_entry *dp;
    + struct dx_root_info *root;
    + int count_offset;
    +
    + if (le16_to_cpu(dirent->rec_len) == EXT4_BLOCK_SIZE(inode->i_sb))
    + count_offset = 8;
    + else if (le16_to_cpu(dirent->rec_len) == 12) {
    + dp = (struct ext4_dir_entry *)(((void *)dirent) + 12);
    + if (le16_to_cpu(dp->rec_len) !=
    + EXT4_BLOCK_SIZE(inode->i_sb) - 12)
    + return NULL;
    + root = (struct dx_root_info *)(((void *)dp + 12));
    + if (root->reserved_zero ||
    + root->info_length != sizeof(struct dx_root_info))
    + return NULL;
    + count_offset = 32;
    + } else
    + return NULL;
    +
    + if (offset)
    + *offset = count_offset;
    + return (struct dx_countlimit *)(((void *)dirent) + count_offset);
    +}
    +
    +static __le32 ext4_dx_csum(struct inode *inode, struct ext4_dir_entry *dirent,
    + int count_offset, int count, struct dx_tail *t)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
    + struct ext4_inode_info *ei = EXT4_I(inode);
    + __u32 csum, old_csum;
    + int size;
    +
    + size = count_offset + (count * sizeof(struct dx_entry));
    + old_csum = t->dt_checksum;
    + t->dt_checksum = 0;
    + csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)dirent, size);
    + csum = ext4_chksum(sbi, csum, (__u8 *)t, sizeof(struct dx_tail));
    + t->dt_checksum = old_csum;
    +
    + return cpu_to_le32(csum);
    +}
    +
    +static int ext4_dx_csum_verify(struct inode *inode,
    + struct ext4_dir_entry *dirent)
    +{
    + struct dx_countlimit *c;
    + struct dx_tail *t;
    + int count_offset, limit, count;
    +
    + if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
    + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
    + return 1;
    +
    + c = get_dx_countlimit(inode, dirent, &count_offset);
    + if (!c) {
    + EXT4_ERROR_INODE(inode, "dir seems corrupt? Run e2fsck -D.");
    + return 1;
    + }
    + limit = le16_to_cpu(c->limit);
    + count = le16_to_cpu(c->count);
    + if (count_offset + (limit * sizeof(struct dx_entry)) >
    + EXT4_BLOCK_SIZE(inode->i_sb) - sizeof(struct dx_tail)) {
    + EXT4_ERROR_INODE(inode, "metadata_csum set but no space for "
    + "tree checksum found. Run e2fsck -D.");
    + return 1;
    + }
    + t = (struct dx_tail *)(((struct dx_entry *)c) + limit);
    +
    + if (t->dt_checksum != ext4_dx_csum(inode, dirent, count_offset,
    + count, t))
    + return 0;
    + return 1;
    +}
    +
    +static void ext4_dx_csum_set(struct inode *inode, struct ext4_dir_entry *dirent)
    +{
    + struct dx_countlimit *c;
    + struct dx_tail *t;
    + int count_offset, limit, count;
    +
    + if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
    + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
    + return;
    +
    + c = get_dx_countlimit(inode, dirent, &count_offset);
    + if (!c) {
    + EXT4_ERROR_INODE(inode, "dir seems corrupt? Run e2fsck -D.");
    + return;
    + }
    + limit = le16_to_cpu(c->limit);
    + count = le16_to_cpu(c->count);
    + if (count_offset + (limit * sizeof(struct dx_entry)) >
    + EXT4_BLOCK_SIZE(inode->i_sb) - sizeof(struct dx_tail)) {
    + EXT4_ERROR_INODE(inode, "metadata_csum set but no space for "
    + "tree checksum. Run e2fsck -D.");
    + return;
    + }
    + t = (struct dx_tail *)(((struct dx_entry *)c) + limit);
    +
    + t->dt_checksum = ext4_dx_csum(inode, dirent, count_offset, count, t);
    +}
    +
    +static inline int ext4_handle_dirty_dx_node(handle_t *handle,
    + struct inode *inode,
    + struct buffer_head *bh)
    +{
    + ext4_dx_csum_set(inode, (struct ext4_dir_entry *)bh->b_data);
    + return ext4_handle_dirty_metadata(handle, inode, bh);
    +}
    +
    /*
    * p is at least 6 bytes before the end of page
    */
    @@ -247,12 +362,20 @@ static inline unsigned dx_root_limit(struct inode *dir, unsigned infosize)
    {
    unsigned entry_space = dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(1) -
    EXT4_DIR_REC_LEN(2) - infosize;
    +
    + if (EXT4_HAS_RO_COMPAT_FEATURE(dir->i_sb,
    + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
    + entry_space -= sizeof(struct dx_tail);
    return entry_space / sizeof(struct dx_entry);
    }

    static inline unsigned dx_node_limit(struct inode *dir)
    {
    unsigned entry_space = dir->i_sb->s_blocksize - EXT4_DIR_REC_LEN(0);
    +
    + if (EXT4_HAS_RO_COMPAT_FEATURE(dir->i_sb,
    + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
    + entry_space -= sizeof(struct dx_tail);
    return entry_space / sizeof(struct dx_entry);
    }

    @@ -398,6 +521,15 @@ dx_probe(const struct qstr *d_name, struct inode *dir,
    goto fail;
    }

    + if (!buffer_verified(bh) &&
    + !ext4_dx_csum_verify(dir, (struct ext4_dir_entry *)bh->b_data)) {
    + ext4_warning(dir->i_sb, "Root failed checksum");
    + brelse(bh);
    + *err = ERR_BAD_DX_DIR;
    + goto fail;
    + }
    + set_buffer_verified(bh);
    +
    entries = (struct dx_entry *) (((char *)&root->info) +
    root->info.info_length);

    @@ -458,6 +590,17 @@ dx_probe(const struct qstr *d_name, struct inode *dir,
    if (!(bh = ext4_bread (NULL,dir, dx_get_block(at), 0, err)))
    goto fail2;
    at = entries = ((struct dx_node *) bh->b_data)->entries;
    +
    + if (!buffer_verified(bh) &&
    + !ext4_dx_csum_verify(dir,
    + (struct ext4_dir_entry *)bh->b_data)) {
    + ext4_warning(dir->i_sb, "Node failed checksum");
    + brelse(bh);
    + *err = ERR_BAD_DX_DIR;
    + goto fail;
    + }
    + set_buffer_verified(bh);
    +
    if (dx_get_limit(entries) != dx_node_limit (dir)) {
    ext4_warning(dir->i_sb,
    "dx entry: limit != node limit");
    @@ -557,6 +700,15 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash,
    if (!(bh = ext4_bread(NULL, dir, dx_get_block(p->at),
    0, &err)))
    return err; /* Failure */
    +
    + if (!buffer_verified(bh) &&
    + !ext4_dx_csum_verify(dir,
    + (struct ext4_dir_entry *)bh->b_data)) {
    + ext4_warning(dir->i_sb, "Node failed checksum");
    + return -EIO;
    + }
    + set_buffer_verified(bh);
    +
    p++;
    brelse(p->bh);
    p->bh = bh;
    @@ -1232,7 +1384,7 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
    err = ext4_handle_dirty_metadata(handle, dir, bh2);
    if (err)
    goto journal_error;
    - err = ext4_handle_dirty_metadata(handle, dir, frame->bh);
    + err = ext4_handle_dirty_dx_node(handle, dir, frame->bh);
    if (err)
    goto journal_error;
    brelse(bh2);
    @@ -1419,7 +1571,7 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
    frame->bh = bh;
    bh = bh2;

    - ext4_handle_dirty_metadata(handle, dir, frame->bh);
    + ext4_handle_dirty_dx_node(handle, dir, frame->bh);
    ext4_handle_dirty_metadata(handle, dir, bh);

    de = do_split(handle,dir, &bh, frame, &hinfo, &retval);
    @@ -1594,7 +1746,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
    dxtrace(dx_show_index("node", frames[1].entries));
    dxtrace(dx_show_index("node",
    ((struct dx_node *) bh2->b_data)->entries));
    - err = ext4_handle_dirty_metadata(handle, dir, bh2);
    + err = ext4_handle_dirty_dx_node(handle, dir, bh2);
    if (err)
    goto journal_error;
    brelse (bh2);
    @@ -1620,7 +1772,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
    if (err)
    goto journal_error;
    }
    - err = ext4_handle_dirty_metadata(handle, dir, frames[0].bh);
    + err = ext4_handle_dirty_dx_node(handle, dir, frames[0].bh);
    if (err) {
    ext4_std_error(inode->i_sb, err);
    goto cleanup;


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      Last update: 2012-03-06 21:53    [W:0.058 / U:60.984 seconds]
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