Re: [PATCH 2/2] Btrfs: add valid checks for chunk loading

Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> · Thu, 5 May 2016 09:03:22 +0800

Liu Bo wrote on 2016/05/03 16:36 -0700:
On Tue, May 03, 2016 at 09:12:01AM +0800, Qu Wenruo wrote:


Liu Bo wrote on 2016/05/02 11:15 -0700:
To prevent fuzz filesystem images from panic the whole system,
we need various validation checks to refuse to mount such an image
if btrfs finds any invalid value during loading chunks, including
both sys_array and regular chunks.

Note that these checks may not be sufficient to cover all corner cases,
feel free to add more checks.

Looks good for me.

But would you mind to do extra check on some minor members like owner,
io_align, io_width and sub_stripes?
Since we have a dedicated function now, if not too hard, it's never a bad
idea to check every member for best robust.

OK.


Especially sub_stripes, as it seems to be used by division in
btrfs_rmap_block().

It makes sense to check sub_stripes, but io_align/width are not used at
this moment, I'd leave it for the future.

What do you think?

Thanks,

-liubo


I'm OK if io_align/width is not used yet.
It's just a personal favor.

Adding such check when we really use io_align/width may be a better idea.

Thanks,
Qu


Thanks,
Qu

Reported-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Reported-by: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
fs/btrfs/volumes.c | 84 +++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 68 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index bd0f45f..1075573 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6206,27 +6206,23 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
	return dev;
}

-static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
-			  struct extent_buffer *leaf,
-			  struct btrfs_chunk *chunk)
+/* Return -EIO if any error, otherwise return 0. */
+static int btrfs_check_chunk_valid(struct btrfs_root *root,
+				   struct extent_buffer *leaf,
+				   struct btrfs_chunk *chunk, u64 logical)
{
-	struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
-	struct map_lookup *map;
-	struct extent_map *em;
-	u64 logical;
	u64 length;
	u64 stripe_len;
-	u64 devid;
-	u8 uuid[BTRFS_UUID_SIZE];
-	int num_stripes;
-	int ret;
-	int i;
+	u16 num_stripes;
+	u16 sub_stripes;
+	u64 type;

-	logical = key->offset;
	length = btrfs_chunk_length(leaf, chunk);
	stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
	num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
-	/* Validation check */
+	sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
+	type = btrfs_chunk_type(leaf, chunk);
+
	if (!num_stripes) {
		btrfs_err(root->fs_info, "invalid chunk num_stripes: %u",
			  num_stripes);
@@ -6237,24 +6233,70 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
			  "invalid chunk logical %llu", logical);
		return -EIO;
	}
+	if (btrfs_chunk_sector_size(leaf, chunk) != root->sectorsize) {
+		btrfs_err(root->fs_info, "invalid chunk sectorsize %llu",
+			  (unsigned long long)btrfs_chunk_sector_size(leaf,
+								      chunk));
+		return -EIO;
+	}
	if (!length || !IS_ALIGNED(length, root->sectorsize)) {
		btrfs_err(root->fs_info,
			"invalid chunk length %llu", length);
		return -EIO;
	}
-	if (!is_power_of_2(stripe_len)) {
+	if (stripe_len != BTRFS_STRIPE_LEN) {
		btrfs_err(root->fs_info, "invalid chunk stripe length: %llu",
			  stripe_len);
		return -EIO;
	}
	if (~(BTRFS_BLOCK_GROUP_TYPE_MASK | BTRFS_BLOCK_GROUP_PROFILE_MASK) &
-	    btrfs_chunk_type(leaf, chunk)) {
+	    type) {
		btrfs_err(root->fs_info, "unrecognized chunk type: %llu",
			  ~(BTRFS_BLOCK_GROUP_TYPE_MASK |
			    BTRFS_BLOCK_GROUP_PROFILE_MASK) &
			  btrfs_chunk_type(leaf, chunk));
		return -EIO;
	}
+	if ((type & BTRFS_BLOCK_GROUP_RAID10 && sub_stripes == 0) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID1 && num_stripes < 1) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID5 && num_stripes < 2) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID5 && num_stripes < 3) ||
+	    (type & BTRFS_BLOCK_GROUP_DUP && num_stripes > 2) ||
+	    ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 &&
+	     num_stripes != 1)) {
+		btrfs_err(root->fs_info, "Invalid num_stripes:sub_stripes %u:%u for profile %llu",
+			  num_stripes, sub_stripes,
+			  type & BTRFS_BLOCK_GROUP_PROFILE_MASK);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
+			  struct extent_buffer *leaf,
+			  struct btrfs_chunk *chunk)
+{
+	struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree;
+	struct map_lookup *map;
+	struct extent_map *em;
+	u64 logical;
+	u64 length;
+	u64 stripe_len;
+	u64 devid;
+	u8 uuid[BTRFS_UUID_SIZE];
+	int num_stripes;
+	int ret;
+	int i;
+
+	logical = key->offset;
+	length = btrfs_chunk_length(leaf, chunk);
+	stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
+	num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+	/* Validation check */
+	ret = btrfs_check_chunk_valid(root, leaf, chunk, logical);
+	if (ret)
+		return ret;

	read_lock(&map_tree->map_tree.lock);
	em = lookup_extent_mapping(&map_tree->map_tree, logical, 1);
@@ -6502,6 +6544,7 @@ int btrfs_read_sys_array(struct btrfs_root *root)
	u32 array_size;
	u32 len = 0;
	u32 cur_offset;
+	u64 type;
	struct btrfs_key key;

	ASSERT(BTRFS_SUPER_INFO_SIZE <= root->nodesize);
@@ -6568,6 +6611,15 @@ int btrfs_read_sys_array(struct btrfs_root *root)
				break;
			}

+			type = btrfs_chunk_type(sb, chunk);
+			if ((type & BTRFS_BLOCK_GROUP_SYSTEM) == 0) {
+				printk(KERN_ERR
+	    "BTRFS: invalid chunk type %llu in sys_array at offset %u\n",
+					type, cur_offset);
+				ret = -EIO;
+				break;
+			}
+
			len = btrfs_chunk_item_size(num_stripes);
			if (cur_offset + len > array_size)
				goto out_short_read;



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