Re: [PATCH 1/2] cifs: during remount, make sure passwords are in sync

[Paulo Alcantara <pc@manguebit.com>]

Shyam Prasad N <nspmangalore@gmail.com> writes:

> On Fri, Nov 8, 2024 at 5:47 PM Shyam Prasad N <nspmangalore@gmail.com> wrote:
>> > What about SMB sessions from cifs_tcon::dfs_ses_list?  I don't see their
>> > password getting updated over remount.
>>
>> This is in our to-do list as well.
>
> I did some code reading around how DFS automount works.
> @Paulo Alcantara Correct me if I'm wrong, but it sounds like we make
> an assumption that when a DFS namespace has a junction to another
> share, the same credentials are to be used to perform the mount of
> that share. Is that always the case?

Yes, it inherits fs_context from the parent mount.  For multiuser
mounts, when uid/gid/cruid are unspecified, we need to update its values
to match real uid/gid from the calling process.

> If we go by that assumption, for password2 to work with DFS mounts, we
> only need to make sure that in cifs_do_automount, cur_ctx passwords
> are synced up to the current ses passwords. That should be quite easy.

Correct.  The fs_context for the automount is dup'ed from the parent
mount.  smb3_fs_context_dup() already dups password2, so it should work.

The 'remount' case isn't still handled, that's why I mentioned it above.
You'd need to set password2 for all sessios in @tcon->dfs_ses_list.

I think we need to update password2 for the multiuser sessions as well
and not only for session from master tcon.