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vfs: remap helper should update destination inode metadata 

Extend generic_remap_file_range_prep to handle inode metadata updates
when remapping into a file.  If the operation can possibly alter the
file contents, we must update the ctime and mtime and remove security
privileges, just like we do for regular file writes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Darrick J. Wong 2018-10-30 10:41:41 +11:00 committed by Dave Chinner
parent 3d28193e1d
commit 8dde90bca6
2 changed files with 19 additions and 23 deletions
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19
fs/read_write.c
View File

@ -1820,6 +1820,25 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
if (ret)
return ret;
/* If can't alter the file contents, we're done. */
if (!(remap_flags & REMAP_FILE_DEDUP)) {
/* Update the timestamps, since we can alter file contents. */
if (!(file_out->f_mode & FMODE_NOCMTIME)) {
ret = file_update_time(file_out);
if (ret)
return ret;
}
/*
* 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)
return ret;
}
return 1;
}
EXPORT_SYMBOL(generic_remap_file_range_prep);

23
fs/xfs/xfs_reflink.c
View File

@ -1372,29 +1372,6 @@ xfs_reflink_remap_prep(
truncate_inode_pages_range(&inode_out->i_data, pos_out,
PAGE_ALIGN(pos_out + *len) - 1);
/* If we're altering the file contents... */
if (!(remap_flags & REMAP_FILE_DEDUP)) {
/*
* ...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);