From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 9250A1775A for ; Tue, 12 Sep 2023 10:27:14 +0000 (UTC) Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DFEE1705; Tue, 12 Sep 2023 03:27:13 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qg0bl-000440-S5; Tue, 12 Sep 2023 12:27:01 +0200 Date: Tue, 12 Sep 2023 12:27:01 +0200 From: Florian Westphal To: Linux regressions mailing list Cc: Pablo Neira Ayuso , Timo Sigurdsson , kadlec@netfilter.org, fw@strlen.de, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, sashal@kernel.org, carnil@debian.org, 1051592@bugs.debian.org Subject: Re: Regression: Commit "netfilter: nf_tables: disallow rule addition to bound chain via NFTA_RULE_CHAIN_ID" breaks ruleset loading in linux-stable Message-ID: <20230912102701.GA13516@breakpoint.cc> References: <20230911213750.5B4B663206F5@dd20004.kasserver.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Linux regression tracking (Thorsten Leemhuis) wrote: > On 12.09.23 00:57, Pablo Neira Ayuso wrote: > > Userspace nftables v1.0.6 generates incorrect bytecode that hits a new > > kernel check that rejects adding rules to bound chains. The incorrect > > bytecode adds the chain binding, attach it to the rule and it adds the > > rules to the chain binding. I have cherry-picked these three patches > > for nftables v1.0.6 userspace and your ruleset restores fine. > > [...] > > Hmmmm. Well, this sounds like a kernel regression to me that normally > should be dealt with on the kernel level, as users after updating the > kernel should never have to update any userspace stuff to continue what > they have been doing before the kernel update. This is a combo of a userspace bug and this new sanity check that rejects the incorrect ordering (adding rules to the already-bound anonymous chain). nf_tables uses a transaction allor-nothing model, this means that any error that occurs during a transaction has to be reverse/undo all the pending changes. This has caused a myriad of bugs already. So while this can be theoretically fixed in the kernel I don't see a sane way to do it. Error unwinding / recovery from deeply nested errors is already too complex for my taste. > Can't the kernel somehow detect the incorrect bytecode and do the right > thing(tm) somehow? Theoretically yes, but I don't feel competent enough to do it, just look at all the UaF bugs of the past month.