netdev - Re: [PATCH net v2] net/tls: prevent skb_orphan() from leaking TLS plain text with offload

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Date:   Wed, 7 Aug 2019 15:54:15 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     David Miller <davem@...emloft.net>,
        Network Development <netdev@...r.kernel.org>,
        davejwatson@...com, borisp@...lanox.com, aviadye@...lanox.com,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        oss-drivers@...ronome.com
Subject: Re: [PATCH net v2] net/tls: prevent skb_orphan() from leaking TLS
 plain text with offload

On Wed, Aug 7, 2019 at 2:47 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> On Wed, Aug 7, 2019 at 2:01 PM Jakub Kicinski
> <jakub.kicinski@...ronome.com> wrote:
> >
> > On Wed, 7 Aug 2019 12:59:00 -0400, Willem de Bruijn wrote:
> > > On Wed, Aug 7, 2019 at 2:06 AM Jakub Kicinski wrote:
> > > > diff --git a/net/core/sock.c b/net/core/sock.c
> > > > index d57b0cc995a0..0f9619b0892f 100644
> > > > --- a/net/core/sock.c
> > > > +++ b/net/core/sock.c
> > > > @@ -1992,6 +1992,20 @@ void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
> > > >  }
> > > >  EXPORT_SYMBOL(skb_set_owner_w);
> > > >
> > > > +static bool can_skb_orphan_partial(const struct sk_buff *skb)
> > > > +{
> > > > +#ifdef CONFIG_TLS_DEVICE
> > > > +       /* Drivers depend on in-order delivery for crypto offload,
> > > > +        * partial orphan breaks out-of-order-OK logic.
> > > > +        */
> > > > +       if (skb->decrypted)
> > > > +               return false;
> > > > +#endif
> > > > +       return (IS_ENABLED(CONFIG_INET) &&
> > > > +               skb->destructor == tcp_wfree) ||
> > >
> > > Please add parentheses around IS_ENABLED(CONFIG_INET) &&
> > > skb->destructor == tcp_wfree
> >
> > Mm.. there are parenthesis around them, maybe I'm being slow,
> > could you show me how?
>
> I mean
>
>     return (skb->destructor == sock_wfree ||
>                (IS_ENABLED(CONFIG_INET) && skb->destructor == tcp_wfree))
>
> In other words, (a || (b && c)) instead of (a || b && c). Though the
> existing code also eschews the extra parentheses.

No, ignore that last bit. It uses #ifdef, of course.