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>

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 3cc8385..ef4aa54 100644 (file)
--- 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;