From: Liu Bo <bo.li.liu@oracle.com>
Date: Fri, 18 Aug 2017 15:15:18 -0600
Subject: Btrfs: add a helper to retrive extent inline ref type
Git-commit: 167ce953ca55bdee20fe56c3c0fa51002435f745
Patch-mainline: v4.14-rc1
References: bsc#1149325

An invalid value of extent inline ref type may be read from a
malicious image which may force btrfs to crash.

This adds a helper which does sanity check for the ref type, so we can
know if it's sane, return he type, otherwise return an error.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minimal tweak const types, causing warnings due to other cleanup patches ]
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 fs/btrfs/ctree.h       |   11 +++++++++++
 fs/btrfs/extent-tree.c |   37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2587,6 +2587,17 @@ static inline gfp_t btrfs_alloc_write_ma
 
 /* extent-tree.c */
 
+enum btrfs_inline_ref_type {
+	BTRFS_REF_TYPE_INVALID =	 0,
+	BTRFS_REF_TYPE_BLOCK =		 1,
+	BTRFS_REF_TYPE_DATA =		 2,
+	BTRFS_REF_TYPE_ANY =		 3,
+};
+
+int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
+				     struct btrfs_extent_inline_ref *iref,
+				     enum btrfs_inline_ref_type is_data);
+
 u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes);
 
 static inline u64 btrfs_calc_trans_metadata_size(struct btrfs_fs_info *fs_info,
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1147,6 +1147,43 @@ static int convert_extent_item_v0(struct
 }
 #endif
 
+/*
+ * is_data == BTRFS_REF_TYPE_BLOCK, tree block type is required,
+ * is_data == BTRFS_REF_TYPE_DATA, data type is requried,
+ * is_data == BTRFS_REF_TYPE_ANY, either type is OK.
+ */
+int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
+				     struct btrfs_extent_inline_ref *iref,
+				     enum btrfs_inline_ref_type is_data)
+{
+	int type = btrfs_extent_inline_ref_type(eb, iref);
+
+	if (type == BTRFS_TREE_BLOCK_REF_KEY ||
+	    type == BTRFS_SHARED_BLOCK_REF_KEY ||
+	    type == BTRFS_SHARED_DATA_REF_KEY ||
+	    type == BTRFS_EXTENT_DATA_REF_KEY) {
+		if (is_data == BTRFS_REF_TYPE_BLOCK) {
+			if (type == BTRFS_TREE_BLOCK_REF_KEY ||
+			    type == BTRFS_SHARED_BLOCK_REF_KEY)
+				return type;
+		} else if (is_data == BTRFS_REF_TYPE_DATA) {
+			if (type == BTRFS_EXTENT_DATA_REF_KEY ||
+			    type == BTRFS_SHARED_DATA_REF_KEY)
+				return type;
+		} else {
+			ASSERT(is_data == BTRFS_REF_TYPE_ANY);
+			return type;
+		}
+	}
+
+	btrfs_print_leaf(eb->fs_info, (struct extent_buffer *) eb);
+	btrfs_err(eb->fs_info, "eb %llu invalid extent inline ref type %d",
+		  eb->start, type);
+	WARN_ON(1);
+
+	return BTRFS_REF_TYPE_INVALID;
+}
+
 static u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
 {
 	u32 high_crc = ~(u32)0;