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

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Message-ID: <20210122160419.GA81247@sequoia>
Date:   Fri, 22 Jan 2021 10:04:19 -0600
From:   Tyler Hicks <code@...icks.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        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>
Subject: Re: [PATCH 1/2] ecryptfs: fix uid translation for setxattr on
 security.capability

On 2021-01-20 08:52:27, Miklos Szeredi wrote:
> 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.

eCryptfs cannot be exported so I do not think this proposed fix to
ecryptfs_setxattr() creates a new regression wrt inode delegation.

Tyler

> 
> Thanks,
> Miklos