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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A54F8C05027 for ; Fri, 17 Feb 2023 09:06:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229637AbjBQJGJ (ORCPT ); Fri, 17 Feb 2023 04:06:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229951AbjBQJGJ (ORCPT ); Fri, 17 Feb 2023 04:06:09 -0500 Received: from mail-qv1-xf2e.google.com (mail-qv1-xf2e.google.com [IPv6:2607:f8b0:4864:20::f2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 311FC5FBFE for ; Fri, 17 Feb 2023 01:06:08 -0800 (PST) Received: by mail-qv1-xf2e.google.com with SMTP id o102so660770qvo.0 for ; Fri, 17 Feb 2023 01:06:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=4p07mdo4O1kAC4M9tEfoLRTI790ovMC9GRvMZKzlD2U=; b=aEQQAJPXWabDjps06YwVNzaXzXFO60efxIFM5ws9vinsS07Moxz8wpPrMGsXbbYC3U Qkxon6lDavJVBWy4EU+gWytEJNxZ8YQGNynCB6eNDueV/DBdAzkv4n2G89ZE5PKJ6cwi aaMqyIyu4hNwyCeFKa01J4UL+IpGwSVgiP+KKjsemJovXpiXuFjCFB7vuqSFf6bvfCAH YQyGGtH92FHMwFMyhnnVGFk3kF6nKaFdr1/TPLs5w0dj8myjXplgOk4EOqy0bxnnFQXq sKtiqdIlcc2XCLn+OYCPSC9JKU0JwVZznP8JVEgHvkImmfwIVH1nvqFzV9WwbaEnpLYQ YIOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=4p07mdo4O1kAC4M9tEfoLRTI790ovMC9GRvMZKzlD2U=; b=0ZYHGLeDgzHrmtPxIyogPXczGKI1maXtvm2dwPnkuitkX12tHM6bUibeVrj07by1ie HDKuumIUgz83MlflBNx8Raiha58gLpBf793BnvhIMcHhwKstyQMEkEajLw1TBcCHGwg8 YEMxp4VnwcD/OMU7RZs9UntOQvB1OYolBPZll6oIQpeDH0r8hq6kaEowtR69hnRUCQUz 5Is2VRYyLKf55v90aPqum/DM6tcJ9TNqQ9CFNsMs8jcWsmx7ZJx4Po8RUeuZY+ZXjMjG Yw1TVC3sTKVv52MXLz12gJG3veOwBSMP/XMisRUB+3qpMHL5okWu0Fh8ktUyOB6TojsM PjYQ== X-Gm-Message-State: AO0yUKWA5JL3VCeFi/gVXEhEtxjM3s9p8W8klZjuPI5K+ZHEX6UnU+Hg xQIeODgrf9c5hD2FxAHx+JA= X-Google-Smtp-Source: AK7set/lnCFNe/sasa3KLqD9bSO8fuT7HhwVwwa9fFBP1of+8o8ydcFvmlTob21g28m0RSXdDdittQ== X-Received: by 2002:a05:6214:2404:b0:537:7d76:ea7c with SMTP id fv4-20020a056214240400b005377d76ea7cmr923480qvb.25.1676624767299; Fri, 17 Feb 2023 01:06:07 -0800 (PST) Received: from krava ([213.208.157.36]) by smtp.gmail.com with ESMTPSA id f5-20020a37d205000000b00729b7d71ac7sm2910126qkj.33.2023.02.17.01.06.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Feb 2023 01:06:06 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Fri, 17 Feb 2023 10:05:58 +0100 To: Joanne Koong Cc: bpf@vger.kernel.org, martin.lau@kernel.org, andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, kernel-team@fb.com Subject: Re: [PATCH v1 bpf-next] bpf: Tidy up verifier checking Message-ID: References: <20230217005451.2438147-1-joannelkoong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230217005451.2438147-1-joannelkoong@gmail.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Feb 16, 2023 at 04:54:51PM -0800, Joanne Koong wrote: > This change refactors check_mem_access() to check against the base type of > the register, and uses switch case checking instead of if / else if > checks. This change also uses the existing clear_called_saved_regs() > function for resetting caller saved regs in check_helper_call(). > > Signed-off-by: Joanne Koong > --- > kernel/bpf/verifier.c | 67 +++++++++++++++++++++++++++++-------------- > 1 file changed, 46 insertions(+), 21 deletions(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 272563a0b770..b40165be2943 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -5317,7 +5317,8 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn > /* for access checks, reg->off is just part of off */ > off += reg->off; > > - if (reg->type == PTR_TO_MAP_KEY) { > + switch (base_type(reg->type)) { > + case PTR_TO_MAP_KEY: > if (t == BPF_WRITE) { > verbose(env, "write to change key R%d not allowed\n", regno); > return -EACCES; > @@ -5329,7 +5330,10 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn > return err; > if (value_regno >= 0) > mark_reg_unknown(env, regs, value_regno); > - } else if (reg->type == PTR_TO_MAP_VALUE) { > + > + break; > + case PTR_TO_MAP_VALUE: > + { I'm getting failure in this test: #92/1 jeq_infer_not_null/jeq_infer_not_null_ptr_to_btfid:FAIL I wonder with this change we execute this case even if there's PTR_MAYBE_NULL set, which we did not do before, so the test won't fail now as expected > struct btf_field *kptr_field = NULL; > > if (t == BPF_WRITE && value_regno >= 0 && > @@ -5369,7 +5373,10 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn > mark_reg_unknown(env, regs, value_regno); > } > } > - } else if (base_type(reg->type) == PTR_TO_MEM) { > + break; > + } SNIP > @@ -5521,7 +5539,17 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn > > if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ)) > mark_reg_unknown(env, regs, value_regno); > - } else { > + break; > + } > + case PTR_TO_BTF_ID: > + if (!type_may_be_null(reg->type)) { > + err = check_ptr_to_btf_access(env, regs, regno, off, size, t, > + value_regno); > + break; > + } else { > + fallthrough; > + } nit, no need for the else branch, just use fallthrough directly > + default: > verbose(env, "R%d invalid mem access '%s'\n", regno, > reg_type_str(env, reg->type)); > return -EACCES; > @@ -8377,10 +8405,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn > return err; > > /* reset caller saved regs */ nit, we could remove the comment as well, the function name says it all jirka > - for (i = 0; i < CALLER_SAVED_REGS; i++) { > - mark_reg_not_init(env, regs, caller_saved[i]); > - check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK); > - } > + clear_caller_saved_regs(env, regs); > > /* helper call returns 64-bit value. */ > regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; > -- > 2.30.2 >