Patch "ovl: update S_ISGID when setting posix ACLs" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

ovl: update S_ISGID when setting posix ACLs

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ovl-update-s_isgid-when-setting-posix-acls.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Miklos Szeredi <[email protected]>
Date: Mon, 31 Oct 2016 14:42:14 +0100
Subject: ovl: update S_ISGID when setting posix ACLs

From: Miklos Szeredi <[email protected]>

commit fd3220d37b1f6f0cab6142d98b0e6c4082e63299 upstream.

This change fixes xfstest generic/375, which failed to clear the setgid bit in the following test case on overlayfs:

touch $testfile
chown 100:100 $testfile
chmod 2755 $testfile
_runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile

---
 fs/overlayfs/super.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

@@ -1026,6 +1026,21 @@ ovl_posix_acl_xattr_set(const struct xat
 
 	posix_acl_release(acl);
 
+	/*
+	 * Check if sgid bit needs to be cleared (actual setacl operation will
+	 * be done with mounter's capabilities and so that won't do it for us).
+	 */
+	if (unlikely(inode->i_mode & S_ISGID) &&
+	    handler->flags == ACL_TYPE_ACCESS &&
+	    !in_group_p(inode->i_gid) &&
+	    !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
+		struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
+
+		err = ovl_setattr(dentry, &iattr);
+		if (err)
+			return err;
+	}
+
 	err = ovl_xattr_set(dentry, handler->name, value, size, flags);
 	if (!err)
 		ovl_copyattr(ovl_inode_real(inode, NULL), inode);

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/ovl-update-s_isgid-when-setting-posix-acls.patch queue-4.8/ovl-fix-get_acl-on-tmpfs.patch queue-4.8/ovl-fsync-after-copy-up.patch