netdev - Re: [PATCH v5 bpf-next 3/9] veth: Avoid drops by oversized packets when XDP is enabled

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Message-ID: <aa000680-a097-cd1a-e4ab-aacf9d172b04@lab.ntt.co.jp>
Date:   Fri, 27 Jul 2018 10:06:41 +0900
From:   Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Toshiaki Makita <toshiaki.makita1@...il.com>,
        netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: [PATCH v5 bpf-next 3/9] veth: Avoid drops by oversized packets
 when XDP is enabled

On 2018/07/27 9:51, Jakub Kicinski wrote:
> On Thu, 26 Jul 2018 23:40:26 +0900, Toshiaki Makita wrote:
>> +		max_mtu = PAGE_SIZE - VETH_XDP_HEADROOM -
>> +			  peer->hard_header_len -
>> +			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
>> +		if (peer->mtu > max_mtu) {
>> +			NL_SET_ERR_MSG_MOD(extack, "Peer MTU is too large to set XDP");
>> +			err = -ERANGE;
>> +			goto err;
>> +		}
> 
> You need to add .ndo_change_mtu and check this condition there too.

I'm setting peer->max_mtu so no need to add .ndo_change_mtu.
Inappropriate MTU will be refused in dev_set_mtu().

-- 
Toshiaki Makita