Re: Misalignment, MIPS, and ip_hdr(skb)->version

Path	csiph.com!eternal-september.org!feeder.eternal-september.org!aioe.org!bofh.it!news.nic.it!robomod
From	"Jason A. Donenfeld" <Jason@zx2c4.com>
Newsgroups	linux.kernel
Subject	Re: Misalignment, MIPS, and ip_hdr(skb)->version
Date	Thu, 08 Dec 2016 01:40:02 +0100
Message-ID	<sLUUG-7mL-19@gated-at.bofh.it> (permalink)
References	<sLPrX-3Kn-9@gated-at.bofh.it> <sLPBD-3ND-5@gated-at.bofh.it> <sLPBD-3ND-3@gated-at.bofh.it> <sLQxI-4mc-11@gated-at.bofh.it>
Dkim-Signature	v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=mime-version :in-reply-to:references:from:date:message-id:subject:to:cc :content-type; s=mail; bh=9rsihvjJ3FTIjBqOBH+8oQbF20I=; b=L2+QQQ AVzzq4zi4GiYSg9qINI2e/W5Qm8e58GvtgwSFOc/NBLL62ExKa/U9PrJrpi9Dkvw FpR94szpE4avQHBdwMRK8Z3R/thck9EG33u6qzeII6dMjgPgSxd7jxnI2r3CIBMl Lw2LteuLUuK5/VWWQ5+UEYIryLYl74yDFqHxxN0DG6ayis26FnBNQK7sK6U3oO9Z OLXmgvXMMQdoe8QarqYHoPdjYDB4nQSKy3rFhAm2E2F9tDxpIVE3ePjrC1dTZ3aO ByAz8TCsKVKY74/x4shHTawj00JOPP1SuDx/mUYJ3EWv8TL61EVna7Tdbv5tRG7r LBKMHK3GFdxCOLew==
X-Gm-Message-State	AKaTC00JROppXOsBlg7qmxRjWPS+oUKHHRRbOjASWxU9K/4UOPjyyOIZHTS8sVfccA8JT1q+Xwbv2yYGESHJ8w==
X-Received	by 10.46.0.87 with SMTP id 84mr30168300lja.1.1481156983222; Wed, 07 Dec 2016 16:29:43 -0800 (PST)
MIME-Version	1.0
X-Gmail-Original-Message-ID	<CAHmME9qxz6wcOZuurqahXeY6QSF=zz0gH7gY4RZujLAJPNSWBA@mail.gmail.com>
Content-Type	text/plain; charset=UTF-8
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	16
Organization	linux.* mail to news gateway
X-Original-Cc	Dave Taht <dave.taht@gmail.com>, Netdev <netdev@vger.kernel.org>, linux-mips@linux-mips.org, LKML <linux-kernel@vger.kernel.org>, WireGuard mailing list <wireguard@lists.zx2c4.com>
X-Original-Date	Thu, 8 Dec 2016 01:29:42 +0100
X-Original-Message-ID	<CAHmME9qxz6wcOZuurqahXeY6QSF=zz0gH7gY4RZujLAJPNSWBA@mail.gmail.com>
X-Original-References	<CAA93jw7hcmkcyD=t4VRrQFfHk+n+EkSVgY6KFDq0_-DGpMADYw@mail.gmail.com> <20161207.135127.789629809982860453.davem@davemloft.net> <CAHmME9oLgjDA2F0gkFzHU2Es8-XCxQHRABS18OKF0EnZgt1=LQ@mail.gmail.com> <20161207.145240.1636297838792223189.davem@davemloft.net>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1538217

Show key headers only | View raw

On Wed, Dec 7, 2016 at 8:52 PM, David Miller <davem@davemloft.net> wrote:
> The only truly difficult case to handle is GRE encapsulation.  Is
> that the situation you are running into?
>
> If not, please figure out what the header configuration looks like
> in the case that hits for you, and what the originating device is
> just in case it is a device driver issue.

My case is my own driver and my own protocol, which uses a 13 byte
header. I can, if absolutely necessary, change the protocol to add
another byte of padding. Or I can choose not to decrypt in place but
rather use a different trick, like overwriting the header during
decryption, though this removes some of the scatterwalk optimizations
when src and dst are the same. Or something else. I wrote the top
email of this thread inquiring about just exactly how bad it is to
call netif_rx(skb) when skb->data is unaligned.

Thread

Misalignment, MIPS, and ip_hdr(skb)->version "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-07 19:40 +0100
  Re: Misalignment, MIPS, and ip_hdr(skb)->version Dave Taht <dave.taht@gmail.com> - 2016-12-07 19:50 +0100
    Re: Misalignment, MIPS, and ip_hdr(skb)->version "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-07 20:00 +0100
      Re: Misalignment, MIPS, and ip_hdr(skb)->version David Miller <davem@davemloft.net> - 2016-12-07 21:00 +0100
        Re: Misalignment, MIPS, and ip_hdr(skb)->version "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-08 01:40 +0100
          Re: Misalignment, MIPS, and ip_hdr(skb)->version David Miller <davem@davemloft.net> - 2016-12-08 01:40 +0100
            Re: Misalignment, MIPS, and ip_hdr(skb)->version "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-08 23:30 +0100
              Re: Misalignment, MIPS, and ip_hdr(skb)->version David Miller <davem@davemloft.net> - 2016-12-09 00:20 +0100
              Re: Misalignment, MIPS, and ip_hdr(skb)->version Willy Tarreau <w@1wt.eu> - 2016-12-11 09:10 +0100
      Re: Misalignment, MIPS, and ip_hdr(skb)->version Felix Fietkau <nbd@nbd.name> - 2016-12-10 13:30 +0100
        Re: Misalignment, MIPS, and ip_hdr(skb)->version Måns Rullgård <mans@mansr.com> - 2016-12-10 14:30 +0100
          Re: Misalignment, MIPS, and ip_hdr(skb)->version Felix Fietkau <nbd@nbd.name> - 2016-12-10 21:20 +0100
            Re: Misalignment, MIPS, and ip_hdr(skb)->version Felix Fietkau <nbd@nbd.name> - 2016-12-10 21:40 +0100
            Re: Misalignment, MIPS, and ip_hdr(skb)->version Måns Rullgård <mans@mansr.com> - 2016-12-10 21:40 +0100
    Re: Misalignment, MIPS, and ip_hdr(skb)->version David Miller <davem@davemloft.net> - 2016-12-07 20:00 +0100
  Re: Misalignment, MIPS, and ip_hdr(skb)->version Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-08 01:40 +0100
    Re: Misalignment, MIPS, and ip_hdr(skb)->version Daniel Kahn Gillmor <dkg@fifthhorseman.net> - 2016-12-08 06:10 +0100
      Re: Misalignment, MIPS, and ip_hdr(skb)->version Jiri Benc <jbenc@redhat.com> - 2016-12-09 12:30 +0100
      Re: Misalignment, MIPS, and ip_hdr(skb)->version Dan Lüdtke <mail@danrl.com> - 2016-12-10 23:30 +0100
        Re: Misalignment, MIPS, and ip_hdr(skb)->version Greg KH <gregkh@linuxfoundation.org> - 2016-12-11 08:20 +0100

csiph-web