linux-kernel - Re: [PATCH 1/2] ecryptfs: fix uid translation for setxattr on security.capability

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Date:   Wed, 20 Jan 2021 08:52:27 +0100
From:   Miklos Szeredi <miklos@...redi.hu>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Miklos Szeredi <mszeredi@...hat.com>,
        linux-fsdevel@...r.kernel.org,
        overlayfs <linux-unionfs@...r.kernel.org>,
        LSM <linux-security-module@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Tyler Hicks <code@...icks.com>
Subject: Re: [PATCH 1/2] ecryptfs: fix uid translation for setxattr on security.capability

On Tue, Jan 19, 2021 at 10:11 PM Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> Miklos Szeredi <mszeredi@...hat.com> writes:
>
> > Prior to commit 7c03e2cda4a5 ("vfs: move cap_convert_nscap() call into
> > vfs_setxattr()") the translation of nscap->rootid did not take stacked
> > filesystems (overlayfs and ecryptfs) into account.
> >
> > That patch fixed the overlay case, but made the ecryptfs case worse.
> >
> > Restore old the behavior for ecryptfs that existed before the overlayfs
> > fix.  This does not fix ecryptfs's handling of complex user namespace
> > setups, but it does make sure existing setups don't regress.
>
> Today vfs_setxattr handles handles a delegated_inode and breaking
> leases.  Code that is enabled with CONFIG_FILE_LOCKING.  So unless
> I am missing something this introduces a different regression into
> ecryptfs.

This is in line with all the other cases of ecryptfs passing NULL as
delegated inode.

I'll defer this to the maintainer of ecryptfs.

Thanks,
Miklos