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Date:   Wed, 20 Jan 2021 13:03:10 +0100
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Jann Horn <jannh@google.com>
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Subject: Re: [PATCH v5 15/42] fs: add file_user_ns() helper
Message-ID: <20210120120310.6tczonwl3rdtnyu3@wittgenstein>
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 <CAG48ez3Ccr77+zH56YGimESf9jdy_xnQrebypn1TXEP3Q+xw=w@mail.gmail.com>
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On Tue, Jan 19, 2021 at 04:05:00PM +0100, Jann Horn wrote:
> On Wed, Jan 13, 2021 at 1:52 AM Christian Brauner
> <christian.brauner@ubuntu.com> wrote:
> > Add a simple helper to retrieve the user namespace associated with the
> > vfsmount of a file. Christoph correctly points out that this makes
> > codepaths (e.g. ioctls) way easier to follow that would otherwise
> > dereference via mnt_user_ns(file->f_path.mnt).
> >
> > In order to make file_user_ns() static inline we'd need to include
> > mount.h in either file.h or fs.h which seems undesirable so let's simply
> > not force file_user_ns() to be inline.
> [...]
> > +struct user_namespace *file_user_ns(struct file *file)
> > +{
> > +       return mnt_user_ns(file->f_path.mnt);
> > +}
> 
> That name is confusing to me, because when I think of "the userns of a
> file", it's file->f_cred->user_ns. There are a bunch of places that
> look at that, as you can see from grepping for "f_cred->user_ns".
> 
> If you really want this to be a separate helper, can you maybe give it
> a clearer name? file_mnt_user_ns(), or something like that, idk.

Done.