xfs: update ctime and remove suid before cloning files

Before cloning into a file, update the ctime and remove sensitive
attributes like suid, just like we'd do for a regular file write.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index f135748d8282..59da9708e9c1 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1264,6 +1264,7 @@ xfs_reflink_zero_posteof(
  * Prepare two files for range cloning.  Upon a successful return both inodes
  * will have the iolock and mmaplock held, the page cache of the out file
  * will be truncated, and any leases on the out file will have been broken.
+ * This function borrows heavily from xfs_file_aio_write_checks.
  */
 STATIC int
 xfs_reflink_remap_prep(
@@ -1327,6 +1328,30 @@ xfs_reflink_remap_prep(
         /* Zap any page cache for the destination file's range. */
         truncate_inode_pages_range(&inode_out->i_data, pos_out,
                                    PAGE_ALIGN(pos_out + *len) - 1);
+
+        /* If we're altering the file contents... */
+        if (!is_dedupe) {
+                /*
+                 * ...update the timestamps (which will grab the ilock again
+                 * from xfs_fs_dirty_inode, so we have to call it before we
+                 * take the ilock).
+                 */
+                if (!(file_out->f_mode & FMODE_NOCMTIME)) {
+                        ret = file_update_time(file_out);
+                        if (ret)
+                                goto out_unlock;
+                }
+
+                /*
+                 * ...clear the security bits if the process is not being run
+                 * by root.  This keeps people from modifying setuid and setgid
+                 * binaries.
+                 */
+                ret = file_remove_privs(file_out);
+                if (ret)
+                        goto out_unlock;
+        }
+
         return 1;
 out_unlock:
         xfs_reflink_remap_unlock(file_in, file_out);