[PATCH 04/25] xfs: update ctime and remove suid before cloning files

Darrick J. Wong
2018-10-10T00:11:06Z

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>
---
fs/xfs/xfs_reflink.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index cbb359e68a72..d4feaeba8542 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.
* Returns negative for error, 0 for nothing to do, and 1 for success.
*/
STATIC int
@@ -1328,6 +1329,30 @@ 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);