From patchwork Mon Aug 2 13:45:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 490716 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 A15B0C4320A for ; Mon, 2 Aug 2021 13:57:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8121A61241 for ; Mon, 2 Aug 2021 13:57:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235240AbhHBN5f (ORCPT ); Mon, 2 Aug 2021 09:57:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:40884 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235258AbhHBNzv (ORCPT ); Mon, 2 Aug 2021 09:55:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 87C4E61104; Mon, 2 Aug 2021 13:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627912457; bh=uo+XnEZ/gLBIhGzItFWbFzgIeSoS3MCOwToZ0rb3Qqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XbpV8BONTslzheyKsVyXdQtAmCg/dGDI7QYEOnsqgKmdEWowa2rcTAa0udlDrQ2pK VGY7naeAzYfpjfQlA2Rw3rE+7Rv1U+Gfk1DJPiF5M0Ayv8cKncTYOWaGS24iqtRvAk cuRyasUinj0jsa3dFTiz0DN9xNkbvNKdnZ8RGwU4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov Subject: [PATCH 5.10 60/67] bpf: Remove superfluous aux sanitation on subprog rejection Date: Mon, 2 Aug 2021 15:45:23 +0200 Message-Id: <20210802134341.096900132@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210802134339.023067817@linuxfoundation.org> References: <20210802134339.023067817@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Borkmann commit 59089a189e3adde4cf85f2ce479738d1ae4c514d upstream. Follow-up to fe9a5ca7e370 ("bpf: Do not mark insn as seen under speculative path verification"). The sanitize_insn_aux_data() helper does not serve a particular purpose in today's code. The original intention for the helper was that if function-by-function verification fails, a given program would be cleared from temporary insn_aux_data[], and then its verification would be re-attempted in the context of the main program a second time. However, a failure in do_check_subprogs() will skip do_check_main() and propagate the error to the user instead, thus such situation can never occur. Given its interaction is not compatible to the Spectre v1 mitigation (due to comparing aux->seen with env->pass_cnt), just remove sanitize_insn_aux_data() to avoid future bugs in this area. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 34 ---------------------------------- 1 file changed, 34 deletions(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11707,37 +11707,6 @@ static void free_states(struct bpf_verif } } -/* The verifier is using insn_aux_data[] to store temporary data during - * verification and to store information for passes that run after the - * verification like dead code sanitization. do_check_common() for subprogram N - * may analyze many other subprograms. sanitize_insn_aux_data() clears all - * temporary data after do_check_common() finds that subprogram N cannot be - * verified independently. pass_cnt counts the number of times - * do_check_common() was run and insn->aux->seen tells the pass number - * insn_aux_data was touched. These variables are compared to clear temporary - * data from failed pass. For testing and experiments do_check_common() can be - * run multiple times even when prior attempt to verify is unsuccessful. - * - * Note that special handling is needed on !env->bypass_spec_v1 if this is - * ever called outside of error path with subsequent program rejection. - */ -static void sanitize_insn_aux_data(struct bpf_verifier_env *env) -{ - struct bpf_insn *insn = env->prog->insnsi; - struct bpf_insn_aux_data *aux; - int i, class; - - for (i = 0; i < env->prog->len; i++) { - class = BPF_CLASS(insn[i].code); - if (class != BPF_LDX && class != BPF_STX) - continue; - aux = &env->insn_aux_data[i]; - if (aux->seen != env->pass_cnt) - continue; - memset(aux, 0, offsetof(typeof(*aux), orig_idx)); - } -} - static int do_check_common(struct bpf_verifier_env *env, int subprog) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); @@ -11807,9 +11776,6 @@ out: if (!ret && pop_log) bpf_vlog_reset(&env->log, 0); free_states(env); - if (ret) - /* clean aux data in case subprog was rejected */ - sanitize_insn_aux_data(env); return ret; }