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([2601:284:8202:10b0:c147:b41e:be5e:8b7a]) by smtp.googlemail.com with ESMTPSA id 94sm9869305qtc.88.2020.07.31.10.27.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Jul 2020 10:27:05 -0700 (PDT) Subject: Re: [PATCH net] net: bridge: clear bridge's private skb space on xmit To: Nikolay Aleksandrov , netdev@vger.kernel.org Cc: bridge@lists.linux-foundation.org, roopa@cumulusnetworks.com, davem@davemloft.net References: <20200731162616.345380-1-nikolay@cumulusnetworks.com> From: David Ahern Message-ID: <07823615-29a8-9553-d56b-1beef55a07bc@gmail.com> Date: Fri, 31 Jul 2020 11:27:03 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200731162616.345380-1-nikolay@cumulusnetworks.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 7/31/20 10:26 AM, Nikolay Aleksandrov wrote: > We need to clear all of the bridge private skb variables as they can be > stale due to the packet being recirculated through the stack and then > transmitted through the bridge device. Similar memset is already done on > bridge's input. We've seen cases where proxyarp_replied was 1 on routed > multicast packets transmitted through the bridge to ports with neigh > suppress which were getting dropped. Same thing can in theory happen with > the port isolation bit as well. > > Fixes: 821f1b21cabb ("bridge: add new BR_NEIGH_SUPPRESS port flag to suppress arp and nd flood") > Signed-off-by: Nikolay Aleksandrov > --- > net/bridge/br_device.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c > index 8c7b78f8bc23..9a2fb4aa1a10 100644 > --- a/net/bridge/br_device.c > +++ b/net/bridge/br_device.c > @@ -36,6 +36,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev) > const unsigned char *dest; > u16 vid = 0; > > + memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); > + > rcu_read_lock(); > nf_ops = rcu_dereference(nf_br_ops); > if (nf_ops && nf_ops->br_dev_xmit_hook(skb)) { > What's the performance hit of doing this on every packet? Can you just set a flag that tells the code to reset on recirculation? Seems like br_input_skb_cb has space for that. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=dMAP5qZPgNkGYL/Es8e27wkRPcvMrbRpgL3nt2uv/U8=; b=DQpUmHoSUZ9Cd93537ypZkM+1dvS3gvkMWCoz3Qx13NPmBpmH4L+gKmanA4eodPVK+ J04ciTphvC/32YS6/AsssAWJdCiJyeCIKz5NoES6FsgkNTeTMfBHwpqq/Y0st/RDULz1 s90EGRs+oMbXy9wM0GoUZ2naiDEY9gSop5clWt0kv0vvi10hVW8C4NrFvOqm1/nyfGwr VqSlZFKNcLXmFmS3OPykN7Q7FfMF/aurchj96d1DyX+1/jlWq3xFkaX+jAweuOZ3N1oM Ffdz2TlQJTZ6E/1rQ7Nne2iW8IWlgbGeezgGumjp1cbCy0+8cSqHHZTwHyvW2HGy+2Gh Cg/Q== References: <20200731162616.345380-1-nikolay@cumulusnetworks.com> From: David Ahern Message-ID: <07823615-29a8-9553-d56b-1beef55a07bc@gmail.com> Date: Fri, 31 Jul 2020 11:27:03 -0600 MIME-Version: 1.0 In-Reply-To: <20200731162616.345380-1-nikolay@cumulusnetworks.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Bridge] [PATCH net] net: bridge: clear bridge's private skb space on xmit List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Nikolay Aleksandrov , netdev@vger.kernel.org Cc: roopa@cumulusnetworks.com, bridge@lists.linux-foundation.org, davem@davemloft.net On 7/31/20 10:26 AM, Nikolay Aleksandrov wrote: > We need to clear all of the bridge private skb variables as they can be > stale due to the packet being recirculated through the stack and then > transmitted through the bridge device. Similar memset is already done on > bridge's input. We've seen cases where proxyarp_replied was 1 on routed > multicast packets transmitted through the bridge to ports with neigh > suppress which were getting dropped. Same thing can in theory happen with > the port isolation bit as well. > > Fixes: 821f1b21cabb ("bridge: add new BR_NEIGH_SUPPRESS port flag to suppress arp and nd flood") > Signed-off-by: Nikolay Aleksandrov > --- > net/bridge/br_device.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c > index 8c7b78f8bc23..9a2fb4aa1a10 100644 > --- a/net/bridge/br_device.c > +++ b/net/bridge/br_device.c > @@ -36,6 +36,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev) > const unsigned char *dest; > u16 vid = 0; > > + memset(skb->cb, 0, sizeof(struct br_input_skb_cb)); > + > rcu_read_lock(); > nf_ops = rcu_dereference(nf_br_ops); > if (nf_ops && nf_ops->br_dev_xmit_hook(skb)) { > What's the performance hit of doing this on every packet? Can you just set a flag that tells the code to reset on recirculation? Seems like br_input_skb_cb has space for that.