netdev - Re: [PATCH v3 2/9] virtio-net: set up xdp for multi buffer packets

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 13 Jan 2023 10:59:51 +0800
From:   Heng Qi <hengqi@...ux.alibaba.com>
To:     Jason Wang <jasowang@...hat.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Subject: Re: [PATCH v3 2/9] virtio-net: set up xdp for multi buffer packets



在 2023/1/13 上午10:49, Jason Wang 写道:
>
> 在 2023/1/3 14:40, Heng Qi 写道:
>> When the xdp program sets xdp.frags, which means it can process
>> multi-buffer packets over larger MTU, so we continue to support xdp.
>> But for single-buffer xdp, we should keep checking for MTU.
>>
>> Signed-off-by: Heng Qi <hengqi@...ux.alibaba.com>
>> Reviewed-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
>> ---
>>   drivers/net/virtio_net.c | 10 ++++++----
>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 443aa7b8f0ad..60e199811212 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -3074,7 +3074,9 @@ static int 
>> virtnet_restore_guest_offloads(struct virtnet_info *vi)
>>   static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog 
>> *prog,
>>                  struct netlink_ext_ack *extack)
>>   {
>> -    unsigned long int max_sz = PAGE_SIZE - sizeof(struct 
>> padded_vnet_hdr);
>> +    unsigned int room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +
>> +                       sizeof(struct skb_shared_info));
>> +    unsigned int max_sz = PAGE_SIZE - room - ETH_HLEN;
>>       struct virtnet_info *vi = netdev_priv(dev);
>>       struct bpf_prog *old_prog;
>>       u16 xdp_qp = 0, curr_qp;
>> @@ -3095,9 +3097,9 @@ static int virtnet_xdp_set(struct net_device 
>> *dev, struct bpf_prog *prog,
>>           return -EINVAL;
>>       }
>>   -    if (dev->mtu > max_sz) {
>> -        NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
>> -        netdev_warn(dev, "XDP requires MTU less than %lu\n", max_sz);
>> +    if (prog && !prog->aux->xdp_has_frags && dev->mtu > max_sz) {
>> +        NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP 
>> without frags");
>> +        netdev_warn(dev, "single-buffer XDP requires MTU less than 
>> %u\n", max_sz);
>>           return -EINVAL;
>>       }
>
>
> I think we probably need to backport this to -stable. So I suggest to 
> move/squash the check of !prog->aux->xdp_has_frags to one of the 
> following patch.

Sure, and you are right.

Thanks.

>
> With this,
>
> Acked-by: Jason Wang <jasowang@...hat.com>
>
> Thanks
>
>