ocfs2: Wrap xattr block reads in a dedicated function

We weren't consistently checking xattr blocks after we read them.
Most places checked the signature, but none checked xb_blkno or
xb_fs_signature.  Create a toplevel ocfs2_read_xattr_block() that does
the read and the validation.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 70 insertions, 24 deletions

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 3cc8385f9738..ef4aa5482d01 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -314,6 +314,65 @@ static void ocfs2_xattr_bucket_copy_data(struct ocfs2_xattr_bucket *dest,
         }
 }
 
+static int ocfs2_validate_xattr_block(struct super_block *sb,
+                                      struct buffer_head *bh)
+{
+        struct ocfs2_xattr_block *xb =
+                (struct ocfs2_xattr_block *)bh->b_data;
+
+        mlog(0, "Validating xattr block %llu\n",
+             (unsigned long long)bh->b_blocknr);
+
+        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
+                ocfs2_error(sb,
+                            "Extended attribute block #%llu has bad "
+                            "signature %.*s",
+                            (unsigned long long)bh->b_blocknr, 7,
+                            xb->xb_signature);
+                return -EINVAL;
+        }
+
+        if (le64_to_cpu(xb->xb_blkno) != bh->b_blocknr) {
+                ocfs2_error(sb,
+                            "Extended attribute block #%llu has an "
+                            "invalid xb_blkno of %llu",
+                            (unsigned long long)bh->b_blocknr,
+                            (unsigned long long)le64_to_cpu(xb->xb_blkno));
+                return -EINVAL;
+        }
+
+        if (le32_to_cpu(xb->xb_fs_generation) != OCFS2_SB(sb)->fs_generation) {
+                ocfs2_error(sb,
+                            "Extended attribute block #%llu has an invalid "
+                            "xb_fs_generation of #%u",
+                            (unsigned long long)bh->b_blocknr,
+                            le32_to_cpu(xb->xb_fs_generation));
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int ocfs2_read_xattr_block(struct inode *inode, u64 xb_blkno,
+                                  struct buffer_head **bh)
+{
+        int rc;
+        struct buffer_head *tmp = *bh;
+
+        rc = ocfs2_read_block(inode, xb_blkno, &tmp);
+        if (!rc) {
+                rc = ocfs2_validate_xattr_block(inode->i_sb, tmp);
+                if (rc)
+                        brelse(tmp);
+        }
+
+        /* If ocfs2_read_block() got us a new bh, pass it up. */
+        if (!rc && !*bh)
+                *bh = tmp;
+
+        return rc;
+}
+
 static inline const char *ocfs2_xattr_prefix(int name_index)
 {
         struct xattr_handler *handler = NULL;
@@ -739,18 +798,14 @@ static int ocfs2_xattr_block_list(struct inode *inode,
         if (!di->i_xattr_loc)
                 return ret;
 
-        ret = ocfs2_read_block(inode, le64_to_cpu(di->i_xattr_loc), &blk_bh);
+        ret = ocfs2_read_xattr_block(inode, le64_to_cpu(di->i_xattr_loc),
+                                     &blk_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 return ret;
         }
 
         xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
-        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
-                ret = -EIO;
-                goto cleanup;
-        }
-
         if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
                 struct ocfs2_xattr_header *header = &xb->xb_attrs.xb_header;
                 ret = ocfs2_xattr_list_entries(inode, header,
@@ -760,7 +815,7 @@ static int ocfs2_xattr_block_list(struct inode *inode,
                 ret = ocfs2_xattr_tree_list_index_block(inode, xt,
                                                    buffer, buffer_size);
         }
-cleanup:
+
         brelse(blk_bh);
 
         return ret;
@@ -1693,24 +1748,19 @@ static int ocfs2_xattr_free_block(struct inode *inode,
         u64 blk, bg_blkno;
         u16 bit;
 
-        ret = ocfs2_read_block(inode, block, &blk_bh);
+        ret = ocfs2_read_xattr_block(inode, block, &blk_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 goto out;
         }
 
-        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
-        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
-                ret = -EIO;
-                goto out;
-        }
-
         ret = ocfs2_xattr_block_remove(inode, blk_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 goto out;
         }
 
+        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
         blk = le64_to_cpu(xb->xb_blkno);
         bit = le16_to_cpu(xb->xb_suballoc_bit);
         bg_blkno = ocfs2_which_suballoc_group(blk, bit);
@@ -1950,19 +2000,15 @@ static int ocfs2_xattr_block_find(struct inode *inode,
         if (!di->i_xattr_loc)
                 return ret;
 
-        ret = ocfs2_read_block(inode, le64_to_cpu(di->i_xattr_loc), &blk_bh);
+        ret = ocfs2_read_xattr_block(inode, le64_to_cpu(di->i_xattr_loc),
+                                     &blk_bh);
         if (ret < 0) {
                 mlog_errno(ret);
                 return ret;
         }
 
-        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
-        if (!OCFS2_IS_VALID_XATTR_BLOCK(xb)) {
-                ret = -EIO;
-                goto cleanup;
-        }
-
         xs->xattr_bh = blk_bh;
+        xb = (struct ocfs2_xattr_block *)blk_bh->b_data;
 
         if (!(le16_to_cpu(xb->xb_flags) & OCFS2_XATTR_INDEXED)) {
                 xs->header = &xb->xb_attrs.xb_header;
@@ -2259,9 +2305,9 @@ meta_guess:
         /* calculate metadata allocation. */
         if (di->i_xattr_loc) {
                 if (!xbs->xattr_bh) {
-                        ret = ocfs2_read_block(inode,
-                                               le64_to_cpu(di->i_xattr_loc),
-                                               &bh);
+                        ret = ocfs2_read_xattr_block(inode,
+                                                     le64_to_cpu(di->i_xattr_loc),
+                                                     &bh);
                         if (ret) {
                                 mlog_errno(ret);
                                 goto out;