From: nb <nikolay.borisov@virtuozzo•com>
To: Ido Schimmel <idosch@idosch•org>
Cc: nhorman@tuxdriver•com, davem@davemloft•net, kuba@kernel•org,
pabeni@redhat•com, netdev@vger•kernel.org, kernel@virtuozzo•com
Subject: Re: [PATCH net-next v2 1/3] drop_monitor: Implement namespace filtering/reporting for software drops
Date: Wed, 23 Nov 2022 17:21:23 +0200 [thread overview]
Message-ID: <7a8bf56c-3db8-63c2-8440-7bbbfb4901ac@virtuozzo.com> (raw)
In-Reply-To: <Y345WyXayWF/2eDJ@shredder>
On 23.11.22 г. 17:16 ч., Ido Schimmel wrote:
> On Wed, Nov 23, 2022 at 04:28:15PM +0200, Nikolay Borisov wrote:
>> static void trace_drop_common(struct sk_buff *skb, void *location)
>> {
>> struct net_dm_alert_msg *msg;
>> @@ -219,7 +233,11 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
>> int i;
>> struct sk_buff *dskb;
>> struct per_cpu_dm_data *data;
>> - unsigned long flags;
>> + unsigned long flags, ns_id = 0;
>> +
>> + if (skb->dev && net_dm_ns &&
>> + dev_net(skb->dev)->ns.inum != net_dm_ns)
>
> I don't think this is going to work, unfortunately. 'skb->dev' is in a
> union with 'dev_scratch' so 'skb->dev' does not necessarily point to a
> valid netdev at all times. It can explode when dev_net() tries to
> dereference it.
>
> __skb_flow_dissect() is doing something similar, but I believe there the
> code paths were audited to make sure it is safe.
>
> Did you consider achieving this functionality with a BPF program
> attached to skb::kfree_skb tracepoint? I believe BPF programs are run
> with page faults disabled, so it should be safe to attempt this there.
How would that be different than the trace_drop_common which is called
as part of the trace_kfree_skb, as it's really passed as trace point
probe via:
net_dm_trace_on_set->register_trace_kfree_skb(trace_drop_common)
next prev parent reply other threads:[~2022-11-23 15:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-23 14:28 [PATCH net-next v2 0/3] Add support for netnamespace filtering in drop monitor Nikolay Borisov
2022-11-23 14:28 ` [PATCH net-next v2 1/3] drop_monitor: Implement namespace filtering/reporting for software drops Nikolay Borisov
2022-11-23 15:16 ` Ido Schimmel
2022-11-23 15:21 ` nb [this message]
2022-11-23 18:10 ` Ido Schimmel
2022-11-24 11:41 ` nb
2022-11-28 7:54 ` Ido Schimmel
2022-11-23 15:33 ` Alexander Lobakin
2022-11-23 16:04 ` nb
2022-11-23 17:16 ` Alexander Lobakin
2022-11-23 14:28 ` [PATCH net-next v2 2/3] drop_monitor: Add namespace filtering/reporting for hardware drops Nikolay Borisov
2022-11-23 15:37 ` Alexander Lobakin
2022-11-23 14:28 ` [PATCH net-next v2 3/3] selftests: net: Add drop monitor tests for namespace filtering functionality Nikolay Borisov
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