From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH net] net: Allow flow dissector to handle non 4-byte aligned headers Date: Sun, 31 Jan 2016 23:06:06 +0100 Message-ID: <20160131220606.GA540@breakpoint.cc> References: <1454276221-3543907-1-git-send-email-tom@herbertland.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, netdev@vger.kernel.org, sowmini.varadhan@oracle.com, kernel-team@fb.com To: Tom Herbert Return-path: Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:60530 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757294AbcAaWGL (ORCPT ); Sun, 31 Jan 2016 17:06:11 -0500 Content-Disposition: inline In-Reply-To: <1454276221-3543907-1-git-send-email-tom@herbertland.com> Sender: netdev-owner@vger.kernel.org List-ID: Tom Herbert wrote: > Call get_unaligned_be32 when we access 32-bit fields in > __skb_flow_dissect. At the beginning check for unlikely case of > 1-byte aligned packet. > > Note that flow_dissector may be asked to parse packet unaligned > fields in two instances: > > 1) Packet from a driver which is aligned to Ethernet header > (2-byte alignment) > 2) Parsing inner headers of a received GRE-TEB packet > > Testing: Ran super_netperf tests did not see a regression. This was on > x86 which does not have problems with unaligned data. > > Signed-off-by: Tom Herbert > --- > net/core/flow_dissector.c | 19 ++++++++++++++----- > 1 file changed, 14 insertions(+), 5 deletions(-) > > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > index d79699c..1c64a1a 100644 > --- a/net/core/flow_dissector.c > +++ b/net/core/flow_dissector.c > @@ -95,7 +95,7 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto, > ports = __skb_header_pointer(skb, thoff + poff, > sizeof(_ports), data, hlen, &_ports); > if (ports) > - return *ports; > + return get_unaligned_be32(ports); This adds an ntohl(), is that intended (same for other places)? > +#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > + if (WARN_ON(((u64)data & 0x1))) > + return false; > +#endif WARN_ON_ONCE ?