From 41275efeeebe46f68b7e3ffb3beb30ff479a2308 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 30 Jul 2012 19:14:04 -0400 Subject: [PATCH] libext2fs: verify and calculate extent tree block checksums Verify and calculate extent tree block checksums when processing filesystems. Signed-off-by: Darrick J. Wong Signed-off-by: Theodore Ts'o --- lib/ext2fs/csum.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++ lib/ext2fs/ext2_err.et.in | 3 ++ lib/ext2fs/ext2fs.h | 6 ++++ lib/ext2fs/extent.c | 21 +++++++++++++ 4 files changed, 109 insertions(+) diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c index 3918a4a..92345cf 100644 --- a/lib/ext2fs/csum.c +++ b/lib/ext2fs/csum.c @@ -30,6 +30,85 @@ #define STATIC static #endif +#define EXT3_EXTENT_TAIL_OFFSET(hdr) (sizeof(struct ext3_extent_header) + \ + (sizeof(struct ext3_extent) * ext2fs_le16_to_cpu((hdr)->eh_max))) + +static struct ext3_extent_tail *get_extent_tail(struct ext3_extent_header *h) +{ + return (struct ext3_extent_tail *)(((void *)h) + + EXT3_EXTENT_TAIL_OFFSET(h)); +} + +static errcode_t ext2fs_extent_block_csum(ext2_filsys fs, ext2_ino_t inum, + struct ext3_extent_header *eh, + __u32 *crc) +{ + int size; + __u32 gen; + errcode_t retval; + struct ext2_inode inode; + + size = EXT3_EXTENT_TAIL_OFFSET(eh) + offsetof(struct ext3_extent_tail, + et_checksum); + + retval = ext2fs_read_inode(fs, inum, &inode); + if (retval) + return retval; + inum = ext2fs_cpu_to_le32(inum); + gen = ext2fs_cpu_to_le32(inode.i_generation); + *crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum, + sizeof(inum)); + *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen)); + *crc = ext2fs_crc32c_le(*crc, (unsigned char *)eh, size); + + return 0; +} + +int ext2fs_extent_block_csum_verify(ext2_filsys fs, ext2_ino_t inum, + struct ext3_extent_header *eh) +{ + errcode_t retval; + __u32 provided, calculated; + struct ext3_extent_tail *t = get_extent_tail(eh); + + /* + * The extent tree structures are accessed in LE order, so we must + * swap the checksum bytes here. + */ + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return 1; + + provided = ext2fs_le32_to_cpu(t->et_checksum); + retval = ext2fs_extent_block_csum(fs, inum, eh, &calculated); + if (retval) + return 0; + + return provided == calculated; +} + +errcode_t ext2fs_extent_block_csum_set(ext2_filsys fs, ext2_ino_t inum, + struct ext3_extent_header *eh) +{ + errcode_t retval; + __u32 crc; + struct ext3_extent_tail *t = get_extent_tail(eh); + + if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) + return 0; + + /* + * The extent tree structures are accessed in LE order, so we must + * swap the checksum bytes here. + */ + retval = ext2fs_extent_block_csum(fs, inum, eh, &crc); + if (retval) + return retval; + t->et_checksum = ext2fs_cpu_to_le32(crc); + return retval; +} + int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group, char *bitmap, int size) { diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in index 4777eae..b15d8d9 100644 --- a/lib/ext2fs/ext2_err.et.in +++ b/lib/ext2fs/ext2_err.et.in @@ -452,4 +452,7 @@ ec EXT2_ET_INODE_CSUM_INVALID, ec EXT2_ET_INODE_BITMAP_CSUM_INVALID, "Inode bitmap checksum does not match bitmap" +ec EXT2_ET_EXTENT_CSUM_INVALID, + "Extent block checksum does not match extent block" + end diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h index 5f4983f..080232e 100644 --- a/lib/ext2fs/ext2fs.h +++ b/lib/ext2fs/ext2fs.h @@ -943,6 +943,12 @@ extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len); extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len); /* csum.c */ +extern errcode_t ext2fs_extent_block_csum_set(ext2_filsys fs, + ext2_ino_t inum, + struct ext3_extent_header *eh); +extern int ext2fs_extent_block_csum_verify(ext2_filsys fs, + ext2_ino_t inum, + struct ext3_extent_header *eh); extern errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group, char *bitmap, int size); extern int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group, diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c index 8828764..da82a2a 100644 --- a/lib/ext2fs/extent.c +++ b/lib/ext2fs/extent.c @@ -455,6 +455,13 @@ retry: return retval; } + if (!(handle->fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) && + !ext2fs_extent_block_csum_verify(handle->fs, handle->ino, + eh)) { + handle->level--; + return EXT2_ET_EXTENT_CSUM_INVALID; + } + newpath->left = newpath->entries = ext2fs_le16_to_cpu(eh->eh_entries); newpath->max_entries = ext2fs_le16_to_cpu(eh->eh_max); @@ -541,6 +548,7 @@ static errcode_t update_path(ext2_extent_handle_t handle) blk64_t blk; errcode_t retval; struct ext3_extent_idx *ix; + struct ext3_extent_header *eh; if (handle->level == 0) { retval = ext2fs_write_inode(handle->fs, handle->ino, @@ -550,6 +558,14 @@ static errcode_t update_path(ext2_extent_handle_t handle) blk = ext2fs_le32_to_cpu(ix->ei_leaf) + ((__u64) ext2fs_le16_to_cpu(ix->ei_leaf_hi) << 32); + /* then update the checksum */ + eh = (struct ext3_extent_header *) + handle->path[handle->level].buf; + retval = ext2fs_extent_block_csum_set(handle->fs, handle->ino, + eh); + if (retval) + return retval; + retval = io_channel_write_blk64(handle->fs->io, blk, 1, handle->path[handle->level].buf); } @@ -958,6 +974,11 @@ static errcode_t extent_node_split(ext2_extent_handle_t handle) new_node_start = ext2fs_le32_to_cpu(EXT_FIRST_INDEX(neweh)->ei_block); + /* then update the checksum */ + retval = ext2fs_extent_block_csum_set(handle->fs, handle->ino, neweh); + if (retval) + goto done; + /* ...and write the new node block out to disk. */ retval = io_channel_write_blk64(handle->fs->io, new_node_pblk, 1, block_buf); -- 1.8.3.1