netdev - Re: [External] Re: [PATCH bpf-next v2] net: Don't allow to attach xdp if bond slave device's upper already has a program

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Message-ID: <c63f8752-527a-4960-a58c-87b6685ac074@bytedance.com>
Date: Tue, 27 Aug 2024 16:02:58 +0800
From: Feng Zhou <zhoufeng.zf@...edance.com>
To: Jiri Pirko <jiri@...nulli.us>, Daniel Borkmann <daniel@...earbox.net>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, ast@...nel.org, hawk@...nel.org,
 john.fastabend@...il.com, bigeasy@...utronix.de, lorenzo@...nel.org,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
 yangzhenze@...edance.com, wangdongdong.6@...edance.com,
 Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [External] Re: [PATCH bpf-next v2] net: Don't allow to attach xdp
 if bond slave device's upper already has a program

在 2024/8/23 21:29, Jiri Pirko 写道:
> Fri, Aug 23, 2024 at 02:07:45PM CEST, daniel@...earbox.net wrote:
>> On 8/23/24 1:55 PM, Jiri Pirko wrote:
>>> Fri, Aug 23, 2024 at 10:42:04AM CEST, zhoufeng.zf@...edance.com wrote:
>>>> From: Feng Zhou <zhoufeng.zf@...edance.com>
>>>>
>>>> Cannot attach when an upper device already has a program, This
>>>> restriction is only for bond's slave devices or team port, and
>>>> should not be accidentally injured for devices like eth0 and vxlan0.
>>>
>>> What if I attach xdp program to solo netdev and then I enslave it
>>> to bond/team netdev that already has xdp program attached?
>>> What prevents me from doing that?
>>
>> In that case the enslaving of the device to bond(/team) must fail as
>> otherwise the latter won't be able to propagate the XDP prog downwards.
> 
> Yep, I don't see that in the code though.
> 
> 

Thanks for your suggestion, I will complete it.

>>
>> Feng, did you double check if we have net or BPF selftest coverage for
>> that? If not might be good to add.
>>
>>>> Reviewed-by: Toke Høiland-Jørgensen <toke@...hat.com>
>>>> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
>>>> ---
>>>> Changelog:
>>>> v1->v2: Addressed comments from Paolo Abeni, Jiri Pirko
>>>> - Use "netif_is_lag_port" relace of "netif_is_bond_slave"
>>>> Details in here:
>>>> https://lore.kernel.org/netdev/3bf84d23-a561-47ae-84a4-e99488fc762b@bytedance.com/T/
>>>>
>>>> net/core/dev.c | 10 ++++++----
>>>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/net/core/dev.c b/net/core/dev.c
>>>> index f66e61407883..49144e62172e 100644
>>>> --- a/net/core/dev.c
>>>> +++ b/net/core/dev.c
>>>> @@ -9502,10 +9502,12 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
>>>> 	}
>>>>
>>>> 	/* don't allow if an upper device already has a program */
>>>> -	netdev_for_each_upper_dev_rcu(dev, upper, iter) {
>>>> -		if (dev_xdp_prog_count(upper) > 0) {
>>>> -			NL_SET_ERR_MSG(extack, "Cannot attach when an upper device already has a program");
>>>> -			return -EEXIST;
>>>> +	if (netif_is_lag_port(dev)) {
>>>> +		netdev_for_each_upper_dev_rcu(dev, upper, iter) {
>>>> +			if (dev_xdp_prog_count(upper) > 0) {
>>>> +				NL_SET_ERR_MSG(extack, "Cannot attach when an upper device already has a program");
>>>> +				return -EEXIST;
>>>> +			}
>>>> 		}
>>>> 	}
>>>>
>>>> -- 
>>>> 2.30.2
>>>>
>>>
>>