Verify and calculate extent tree block checksums when processing filesystems.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
lib/ext2fs/csum.c | 75 +++++++++++++++++++++++++++++++++++++++++++++
lib/ext2fs/ext2fs.h | 6 ++++
lib/ext2fs/ext3_extents.h | 11 +++++++
lib/ext2fs/extent.c | 21 +++++++++++++
4 files changed, 113 insertions(+), 0 deletions(-)
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 524d0e5..7f2d5af 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -30,6 +30,81 @@
#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 ncrc;
+ errcode_t retval = 0;
+
+ size = EXT3_EXTENT_TAIL_OFFSET(eh) + offsetof(struct ext3_extent_tail,
+ et_checksum);
+
+ inum = ext2fs_cpu_to_le32(inum);
+ ncrc = ext2fs_crc32c_le(~0, fs->super->s_uuid,
+ sizeof(fs->super->s_uuid));
+ ncrc = ext2fs_crc32c_le(ncrc, (unsigned char *)&inum, sizeof(inum));
+ ncrc = ext2fs_crc32c_le(ncrc, (unsigned char *)eh, size);
+ *crc = ncrc;
+
+ return retval;
+}
+
+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;
+}
+
static __u32 ext2fs_bitmap_csum(ext2_filsys fs, dgrp_t group, char *bitmap,
int size)
{
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 3b514a7..bf2a9e0 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -929,6 +929,12 @@ 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/ext3_extents.h b/lib/ext2fs/ext3_extents.h
index 88fabc9..99a4f47 100644
--- a/lib/ext2fs/ext3_extents.h
+++ b/lib/ext2fs/ext3_extents.h
@@ -19,6 +19,17 @@
*/
/*
+ * This is extent tail on-disk structure.
+ * All other extent structures are 12 bytes long. It turns out that
+ * block_size % 12 >= 4 for all valid block sizes (1k, 2k, 4k).
+ * Therefore, this tail structure can be crammed into the end of the block
+ * without having to rebalance the tree.
+ */
+struct ext3_extent_tail {
+ __u32 et_checksum; /* crc32c(uuid+inum+extent_block) */
+};
+
+/*
* this is extent on-disk structure
* it's used at the bottom of the tree
*/
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index eb096d6..9cb5984 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_HEADER_BAD;
+ }
+
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);
--
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