From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ganesha.gnumonks.org (ganesha.gnumonks.org [213.95.27.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 555111DE2A2; Tue, 8 Oct 2024 14:30:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.27.120 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728397846; cv=none; b=Zi5LWK1hR4KMoPdUQi4kxFo3HmFkZkejvRS7WsVkeFCWo4Y340MIB9wEz660O0Z4m1hTJduoy0A2NxmFqNFyivgQlXmMz+NFjMYLtz6j19AhucMLK+NRWsCedmdjwrJcDXoAh00koc1/lyYKMxiM6w0FijMerTHlMyDbdyfEBAg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728397846; c=relaxed/simple; bh=i51JtwopsuEOuZ9GwW2Cc+uwa+xFhCmxbKyOy+E0zZc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TBKZ0KjqcVOdgLdUIJkLUoFrZfb0WWBoTKBnAmukIrFitLO8bdKD8vc9XP0MSMINyOz07ucSFCktUwD18QmYu8T4q8+olH9LW9VF8E3lSoj3vc77VF4GIuSWRZoUwTgTUZTtGgY2dj3sC/PgoKMa2AOCnrwmpoCcGkzo6UZEnMA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=gnumonks.org; arc=none smtp.client-ip=213.95.27.120 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gnumonks.org Received: from [78.30.37.63] (port=40278 helo=gnumonks.org) by ganesha.gnumonks.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1syBET-008caQ-3f; Tue, 08 Oct 2024 16:30:39 +0200 Date: Tue, 8 Oct 2024 16:30:35 +0200 From: Pablo Neira Ayuso To: Nikolay Aleksandrov Cc: Amedeo Baragiola , Roopa Prabhu , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , bridge@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] bridge: use promisc arg instead of skb flags Message-ID: References: <20241005014514.1541240-1-ingamedeo@gmail.com> Precedence: bulk X-Mailing-List: bridge@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Spam-Score: -1.9 (-) Hi Nikolay, On Sat, Oct 05, 2024 at 05:06:56PM +0300, Nikolay Aleksandrov wrote: > On 05/10/2024 04:44, Amedeo Baragiola wrote: > > Since commit 751de2012eaf ("netfilter: br_netfilter: skip conntrack input hook for promisc packets") > > a second argument (promisc) has been added to br_pass_frame_up which > > represents whether the interface is in promiscuous mode. However, > > internally - in one remaining case - br_pass_frame_up checks the device > > flags derived from skb instead of the argument being passed in. > > This one-line changes addresses this inconsistency. > > > > Signed-off-by: Amedeo Baragiola > > --- > > net/bridge/br_input.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > > index ceaa5a89b947..156c18f42fa3 100644 > > --- a/net/bridge/br_input.c > > +++ b/net/bridge/br_input.c > > @@ -50,8 +50,7 @@ static int br_pass_frame_up(struct sk_buff *skb, bool promisc) > > * packet is allowed except in promisc mode when someone > > * may be running packet capture. > > */ > > - if (!(brdev->flags & IFF_PROMISC) && > > - !br_allowed_egress(vg, skb)) { > > + if (!promisc && !br_allowed_egress(vg, skb)) { > > kfree_skb(skb); > > return NET_RX_DROP; > > } > > This is subtle, but it does change behaviour when a BR_FDB_LOCAL dst > is found it will always drop the traffic after this patch (w/ promisc) if it > doesn't pass br_allowed_egress(). It would've been allowed before, but current > situation does make the patch promisc bit inconsistent, i.e. we get > there because of BR_FDB_LOCAL regardless of the promisc flag. > > Because we can have a BR_FDB_LOCAL dst and still pass up such skb because of > the flag instead of local_rcv (see br_br_handle_frame_finish()). > > CCing also Pablo for a second pair of eyes and as the original patch > author. :) > > Pablo WDYT? > > Just FYI we definitely want to see all traffic if promisc is set, so > this patch is a no-go. promisc is always _false_ for BR_FDB_LOCAL dst: if (dst) { unsigned long now = jiffies; if (test_bit(BR_FDB_LOCAL, &dst->flags)) return br_pass_frame_up(skb, false); ... } if (local_rcv) return br_pass_frame_up(skb, promisc); > > - if (!(brdev->flags & IFF_PROMISC) && > > - !br_allowed_egress(vg, skb)) { > > + if (!promisc && !br_allowed_egress(vg, skb)) { Then, this is not equivalent. But, why is br_allowed_egress() skipped depending on brdev->flags & IFF_PROMISC? I mean, how does this combination work? BR_FDB_LOCAL dst AND (brdev->flags & IFF_PROMISC) AND BR_INPUT_SKB_CB(skb)->vlan_filtered > > kfree_skb(skb); > > return NET_RX_DROP; > > }