From dbe89444042ab6540bc304343cfdcbc8b95d003d Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Sun, 29 Apr 2012 18:39:10 -0400 Subject: [PATCH] ext4: Calculate and verify checksums for htree nodes 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 Signed-off-by: "Theodore Ts'o" --- fs/ext4/namei.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 156 insertions(+), 4 deletions(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 625125172d0..f8efedde759 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; -- 2.20.1