netdev - Re: [RFC 2/2] e1000e: Support RXALL feature flag.

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Date:	Tue, 07 Feb 2012 16:19:01 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Michał Mirosław <mirqus@...il.com>
CC:	netdev@...r.kernel.org
Subject: Re: [RFC 2/2] e1000e: Support RXALL feature flag.

On 02/07/2012 04:06 PM, Michał Mirosław wrote:
> 2012/2/8<greearb@...delatech.com>:
>> From: Ben Greear<greearb@...delatech.com>
>>
>> This allows the NIC to receive all frames available, including
>> those with bad FCS, un-matched vlans, ethernet control frames,
>> and more.
>>
>> Tested by sending frames with bad FCS.
>
> This should probably mark the bad packets somehow, so they are not
> passed up the stack and mixed with correct traffic.

Anything that does higher-level checksumming should figure out the
problem, if it's real (ie, if not *just* a corrupted FCS).  Anything
that doesn't is open to abuse by something sending corrupted packets
with correct checksums anyway.

But, if you think it's really needed, I could add a flag to the skb and
then free the skb after the ptype_all logic in netif_receive_skb
has been called?

>> @@ -2996,6 +3001,25 @@ static void e1000_setup_rctl(struct e1000_adapter *adapter)
>>                 ew32(PSRCTL, psrctl);
>>         }
>>
>> +       /* This is useful for sniffing bad packets. */
>> +       if (adapter->netdev->features&  NETIF_F_RXALL) {
>> +               rctl |= (E1000_RCTL_SBP | /* Receive bad packets */
>> +                        E1000_RCTL_UPE | /* RX all Unicast Pkts */
>> +                        E1000_RCTL_MPE | /* RX all Mcast Pkts */
>> +                        E1000_RCTL_BAM | /* RX All Bcast Pkts Pkts */
>> +                        E1000_RCTL_PMCF); /* RX All MAC Ctrl Pkts */
>> +
>> +               rctl&= ~(E1000_RCTL_VFE | /* Disable VLAN filter */
>> +                         E1000_RCTL_DPF | /* Allow filtered pause */
>> +                         E1000_RCTL_CFIEN); /* Dis VLAN CFIEN Filter */
>> +               /* disable VLAN tagging/striping */
>> +               /* SKIP This, it also affects transmit side and
>> +                  screws up VLANs --Ben. */
>> +               /* ctrl = er32(CTRL); */
>> +               /* ctrl&= ~E1000_CTRL_VME; */
>> +               /* ew32(CTRL, ctrl); */
>> +       }
>> +
> [...]
>
> Looks like it can be enabled independently of promisc mode: rx-all +
> no-promisc would receive only bad packets destined for this host.

Sure, that seems useful.  I'll work on that for rev 2.

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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