From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH 1/3] ipv6: Select fragment id during UFO/GSO segmentation if not set. Date: Tue, 27 Jan 2015 09:26:15 -0500 Message-ID: <54C7A007.6050707@redhat.com> References: <1422283026-27832-1-git-send-email-vyasevic@redhat.com> <1422283026-27832-2-git-send-email-vyasevic@redhat.com> <1422326874.31046.239.camel@decadent.org.uk> <20150127084208.GB21584@redhat.com> <1422366458.13969.11.camel@stressinduktion.org> Reply-To: vyasevic@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Vladislav Yasevich , Ben Hutchings , edumazet@google.com, virtualization@lists.linux-foundation.org To: Hannes Frederic Sowa , "Michael S. Tsirkin" Return-path: In-Reply-To: <1422366458.13969.11.camel@stressinduktion.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On 01/27/2015 08:47 AM, Hannes Frederic Sowa wrote: > On Di, 2015-01-27 at 10:42 +0200, Michael S. Tsirkin wrote: >> On Tue, Jan 27, 2015 at 02:47:54AM +0000, Ben Hutchings wrote: >>> On Mon, 2015-01-26 at 09:37 -0500, Vladislav Yasevich wrote: >>>> If the IPv6 fragment id has not been set and we perform >>>> fragmentation due to UFO, select a new fragment id. >>>> When we store the fragment id into skb_shinfo, set the bit >>>> in the skb so we can re-use the selected id. >>>> This preserves the behavior of UFO packets generated on the >>>> host and solves the issue of id generation for packet sockets >>>> and tap/macvtap devices. >>>> >>>> This patch moves ipv6_select_ident() back in to the header file. >>>> It also provides the helper function that sets skb_shinfo() frag >>>> id and sets the bit. >>>> >>>> It also makes sure that we select the fragment id when doing >>>> just gso validation, since it's possible for the packet to >>>> come from an untrusted source (VM) and be forwarded through >>>> a UFO enabled device which will expect the fragment id. >>>> >>>> CC: Eric Dumazet >>>> Signed-off-by: Vladislav Yasevich >>>> --- >>>> include/linux/skbuff.h | 3 ++- >>>> include/net/ipv6.h | 2 ++ >>>> net/ipv6/ip6_output.c | 4 ++-- >>>> net/ipv6/output_core.c | 9 ++++++++- >>>> net/ipv6/udp_offload.c | 10 +++++++++- >>>> 5 files changed, 23 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h >>>> index 85ab7d7..3ad5203 100644 >>>> --- a/include/linux/skbuff.h >>>> +++ b/include/linux/skbuff.h >>>> @@ -605,7 +605,8 @@ struct sk_buff { >>>> __u8 ipvs_property:1; >>>> __u8 inner_protocol_type:1; >>>> __u8 remcsum_offload:1; >>>> - /* 3 or 5 bit hole */ >>>> + __u8 ufo_fragid_set:1; >>> [...] >>> >>> Doesn't the flag belong in struct skb_shared_info, rather than struct >>> sk_buff? Otherwise this looks fine. >>> >>> Ben. >> >> Hmm we seem to be out of tx flags. >> Maybe ip6_frag_id == 0 should mean "not set". > > Maybe that is the best idea. Definitely the ufo_fragid_set bit should > move into the skb_shared_info area. That's what I originally wanted to do, but had to move and grow txflags thus skb_shinfo ended up growing. I wanted to avoid that, so stole an skb flag. I considered treating fragid == 0 as unset, but a 0 fragid is perfectly valid from the protocol perspective and could actually be generated by the id generator functions. This may cause us to call the id generation multiple times. -vlad > > Thanks, > Hannes > >