From: Ido Schimmel <idosch@idosch.org>
To: Nikolay Borisov <nikolay.borisov@virtuozzo.com>
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 17:16:43 +0200 [thread overview]
Message-ID: <Y345WyXayWF/2eDJ@shredder> (raw)
In-Reply-To: <20221123142817.2094993-2-nikolay.borisov@virtuozzo.com>
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.
next prev parent reply other threads:[~2022-11-23 15:17 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 [this message]
2022-11-23 15:21 ` nb
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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