[PATCH 3.16 040/245] btrfs: Add sanity check for EXTENT_DATA when reading out leaf

Ben Hutchings
2020-04-23T23:24:03Z

From: Qu Wenruo <quwenruo.btrfs@gmx.com>

commit 40c3c40947324d9f40bf47830c92c59a9bbadf4a upstream.

Add extra checks for item with EXTENT_DATA type. This checks the
following thing:

0) Key offset
All key offsets must be aligned to sectorsize.
Inline extent must have 0 for key offset.

1) Item size
Uncompressed inline file extent size must match item size.
(Compressed inline file extent has no information about its on-disk size.)
Regular/preallocated file extent size must be a fixed value.

2) Every member of regular file extent item
Including alignment for bytenr and offset, possible value for
compression/encryption/type.

3) Type/compression/encode must be one of the valid values.

This should be the most comprehensive and strict check in the context
of btrfs_item for EXTENT_DATA.

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ switch to BTRFS_FILE_EXTENT_TYPES, similar to what
BTRFS_COMPRESS_TYPES does ]
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 4.4:
- Use root->sectorsize instead of root->fs_info->sectorsize
- Adjust filename]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/ctree.h | 1 +
fs/btrfs/disk-io.c | 103 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+)

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -874,6 +874,7 @@ struct btrfs_balance_item {
#define BTRFS_FILE_EXTENT_INLINE 0
#define BTRFS_FILE_EXTENT_REG 1
#define BTRFS_FILE_EXTENT_PREALLOC 2
+#define BTRFS_FILE_EXTENT_TYPES 2

struct btrfs_file_extent_item {
/*
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -513,6 +513,100 @@ static int check_tree_block_fsid(struct
btrfs_header_level(eb) == 0 ? "leaf" : "node",\
reason, btrfs_header_bytenr(eb), root->objectid, slot)

+static int check_extent_data_item(struct btrfs_root *root,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ struct btrfs_file_extent_item *fi;
+ u32 sectorsize = root->sectorsize;
+ u32 item_size = btrfs_item_size_nr(leaf, slot);
+
+ if (!IS_ALIGNED(key->offset, sectorsize)) {
+ CORRUPT("unaligned key offset for file extent",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+
+ if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
+ CORRUPT("invalid file extent type", leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /*
+ * Support for new compression/encrption must introduce incompat flag,
+ * and must be caught in open_ctree().
+ */
+ if (btrfs_file_extent_compression(leaf, fi) > BTRFS_COMPRESS_TYPES) {
+ CORRUPT("invalid file extent compression", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (btrfs_file_extent_encryption(leaf, fi)) {
+ CORRUPT("invalid file extent encryption", leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
+ /* Inline extent must have 0 as key offset */
+ if (key->offset) {
+ CORRUPT("inline extent has non-zero key offset",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ /* Compressed inline extent has no on-disk size, skip it */
+ if (btrfs_file_extent_compression(leaf, fi) !=
+ BTRFS_COMPRESS_NONE)
+ return 0;
+
+ /* Uncompressed inline extent size must match item size */
+ if (item_size != BTRFS_FILE_EXTENT_INLINE_DATA_START +
+ btrfs_file_extent_ram_bytes(leaf, fi)) {
+ CORRUPT("plaintext inline extent has invalid size",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+ return 0;
+ }
+
+ /* Regular or preallocated extent has fixed item size */
+ if (item_size != sizeof(*fi)) {
+ CORRUPT(
+ "regluar or preallocated extent data item size is invalid",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+ if (!IS_ALIGNED(btrfs_file_extent_ram_bytes(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_disk_bytenr(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_disk_num_bytes(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_offset(leaf, fi), sectorsize) ||
+ !IS_ALIGNED(btrfs_file_extent_num_bytes(leaf, fi), sectorsize)) {
+ CORRUPT(
+ "regular or preallocated extent data item has unaligned value",
+ leaf, root, slot);
+ return -EUCLEAN;
+ }
+
+ return 0;
+}
+
+/*
+ * Common point to switch the item-specific validation.
+ */
+static int check_leaf_item(struct btrfs_root *root,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ int ret = 0;
+
+ switch (key->type) {
+ case BTRFS_EXTENT_DATA_KEY:
+ ret = check_extent_data_item(root, leaf, key, slot);
+ break;
+ }
+ return ret;
+}
+
static noinline int check_leaf(struct btrfs_root *root,
struct extent_buffer *leaf)
{
@@ -568,9 +662,13 @@ static noinline int check_leaf(struct bt
* 1) key order
* 2) item offset and size
* No overlap, no hole, all inside the leaf.
+ * 3) item content
+ * If possible, do comprehensive sanity check.
+ * NOTE: All checks must only rely on the item data itself.
*/
for (slot = 0; slot < nritems; slot++) {
u32 item_end_expected;
+ int ret;

btrfs_item_key_to_cpu(leaf, &key, slot);

@@ -613,6 +711,11 @@ static noinline int check_leaf(struct bt
return -EUCLEAN;
}

+ /* Check if the item size and content meet other criteria */
+ ret = check_leaf_item(root, leaf, &key, slot);
+ if (ret < 0)
+ return ret;
+
prev_key.objectid = key.objectid;
prev_key.type = key.type;
prev_key.offset = key.offset;