From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=m7kvnCIA8Q8CgdEoOu+s5wkPoNsO/hKQY1wjXm85SX4=; b=aY9bI+99eGtfT2nh5kRtUyLtNqGnRY1IQowjE2kCeV/OEpQ6lXE+QXDUnb7BbU0RHOeCoDoOKrviw9Aug8BeyHt5phY+bdFV6lWR9faxYyO9psguXPGemNqoJjokKPPVlnEjyt8jM44OQtDF0v4VjRYGUCyeJfcGO1MLE86mFOTVT3yYYInGAJq91QrkF3G4klBEWZQYyBImvPmjGtxuvPstwaLvqB7gMaIC/bCdXtz7z6DTkx8Lz+uqDlwVGFTsXeW/yZH897I2KQfbQJ4qKS8894vZUdh5EifZ6VgCwfozKy6ndHKRt5UZw2NLX79HtjXpP1O0+utBRh6GxHsKYQ== References: <20210801231730.7493-1-vladimir.oltean@nxp.com> <20210809160521.audhnv7o2tugwtmp@skbuf> <20210810100928.uk7dfstrnts2may4@skbuf> From: Nikolay Aleksandrov Message-ID: Date: Tue, 10 Aug 2021 13:15:32 +0300 In-Reply-To: <20210810100928.uk7dfstrnts2may4@skbuf> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit MIME-Version: 1.0 Subject: Re: [Bridge] [PATCH net] net: bridge: validate the NUD_PERMANENT bit when adding an extern_learn FDB entry List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Oltean , Ido Schimmel Cc: "syzbot+9ba1174359adba5a5b7c@syzkaller.appspotmail.com" , Jiri Pirko , "netdev@vger.kernel.org" , "bridge@lists.linux-foundation.org" , syzkaller-bugs , Roopa Prabhu , Jakub Kicinski , "David S. Miller" On 10/08/2021 13:09, Vladimir Oltean wrote: > On Tue, Aug 10, 2021 at 09:46:34AM +0300, Ido Schimmel wrote: >> On Mon, Aug 09, 2021 at 04:05:22PM +0000, Vladimir Oltean wrote: >>> On Mon, Aug 09, 2021 at 03:16:40PM +0300, Ido Schimmel wrote: >>>> I have at least once selftest where I forgot the 'static' keyword: >>>> >>>> bridge fdb add de:ad:be:ef:13:37 dev $swp1 master extern_learn vlan 1 >>>> >>>> This patch breaks the test when run against both the kernel and hardware >>>> data paths. I don't mind patching these tests, but we might get more >>>> reports in the future. >>> >>> Is it the 'static' keyword that you forgot, or 'dynamic'? The >>> tools/testing/selftests/net/forwarding/bridge_vlan_aware.sh selftest >>> looks to me like it's testing the behavior of an FDB entry which should >>> roam, and which without the extern_learn flag would be ageable. >> >> static - no aging, no roaming >> dynamic - aging, roaming >> extern_learn - no aging, roaming >> >> So these combinations do not make any sense and the kernel will ignore >> static/dynamic when extern_learn is specified. It's needed to work >> around iproute2 behavior of "assume permanent" > > Since NTF_EXT_LEARNED is part of ndm->ndm_flags and NUD_REACHABLE/NUD_NOARP > are part of ndm->ndm_state, it is not at all clear to me that 'extern_learn' > belongs to the same class of bridge neighbor attributes as 'static'/'dynamic', > and that it is invalid to have the full degree of freedom. If it isn't, > shouldn't the kernel validate that, instead of just ignoring the ndm->ndm_state? > If it's too late to validate, shouldn't we at least document somewhere > that the ndm_state is ignored in the presence of ndm_flags & NTF_EXT_LEARNED? > It is user API after all, easter eggs like this aren't very enjoyable. > It's too late unfortunately, ignoring other flags in that case has been the standard behaviour for a long time (it has never made sense to specify flags for extern_learn entries). I'll send a separate patch that adds a comment to document it or if you have another thing in mind feel free to send a patch. Thanks, Nik