From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAA38C433F4 for ; Wed, 22 Jul 2020 14:40:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCCCF20787 for ; Wed, 22 Jul 2020 14:40:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732720AbgGVOkt (ORCPT ); Wed, 22 Jul 2020 10:40:49 -0400 Received: from www62.your-server.de ([213.133.104.62]:54594 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727825AbgGVOks (ORCPT ); Wed, 22 Jul 2020 10:40:48 -0400 Received: from sslproxy01.your-server.de ([78.46.139.224]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1jyFvH-0000Al-9o; Wed, 22 Jul 2020 16:40:43 +0200 Received: from [178.196.57.75] (helo=pc-9.home) by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jyFvH-000Rx7-4E; Wed, 22 Jul 2020 16:40:43 +0200 Subject: Re: [PATCH v2 bpf-next 2/6] bpf: propagate poke descriptors to subprograms To: Maciej Fijalkowski , ast@kernel.org Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, bjorn.topel@intel.com, magnus.karlsson@intel.com References: <20200721115321.3099-1-maciej.fijalkowski@intel.com> <20200721115321.3099-3-maciej.fijalkowski@intel.com> From: Daniel Borkmann Message-ID: <29a3dcfc-9d85-c113-19d2-e33f80ce5430@iogearbox.net> Date: Wed, 22 Jul 2020 16:40:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20200721115321.3099-3-maciej.fijalkowski@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.3/25880/Tue Jul 21 16:34:58 2020) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 7/21/20 1:53 PM, Maciej Fijalkowski wrote: > Previously, there was no need for poke descriptors being present in > subprogram's bpf_prog_aux struct since tailcalls were simply not allowed > in them. Each subprog is JITed independently so in order to enable > JITing such subprograms, simply copy poke descriptors from main program > to subprogram's poke tab. > > Add also subprog's aux struct to the BPF map poke_progs list by calling > on it map_poke_track(). > > Signed-off-by: Maciej Fijalkowski > --- > kernel/bpf/verifier.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 3c1efc9d08fd..3428edf85220 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -9936,6 +9936,9 @@ static int jit_subprogs(struct bpf_verifier_env *env) > goto out_undo_insn; > > for (i = 0; i < env->subprog_cnt; i++) { > + struct bpf_map *map_ptr; > + int j; > + > subprog_start = subprog_end; > subprog_end = env->subprog_info[i + 1].start; > > @@ -9960,6 +9963,23 @@ static int jit_subprogs(struct bpf_verifier_env *env) > func[i]->aux->btf = prog->aux->btf; > func[i]->aux->func_info = prog->aux->func_info; > > + for (j = 0; j < prog->aux->size_poke_tab; j++) { > + int ret; > + > + ret = bpf_jit_add_poke_descriptor(func[i], > + &prog->aux->poke_tab[j]); > + if (ret < 0) { > + verbose(env, "adding tail call poke descriptor failed\n"); > + goto out_free; > + } > + map_ptr = func[i]->aux->poke_tab[j].tail_call.map; > + ret = map_ptr->ops->map_poke_track(map_ptr, func[i]->aux); > + if (ret < 0) { > + verbose(env, "tracking tail call prog failed\n"); > + goto out_free; > + } Hmm, I don't think this is correct/complete. If some of these have been registered or if later on the JIT'ing fails but the subprog is already exposed to the prog array then it's /public/ at this point, so a later bpf_jit_free() in out_free will rip them mem while doing live patching on prog updates leading to UAF. > + } > + > /* Use bpf_prog_F_tag to indicate functions in stack traces. > * Long term would need debug info to populate names > */ >