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 369BEC433EF for ; Tue, 22 Feb 2022 06:53:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230301AbiBVGyR (ORCPT ); Tue, 22 Feb 2022 01:54:17 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:38706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230290AbiBVGyQ (ORCPT ); Tue, 22 Feb 2022 01:54:16 -0500 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1480D1110A2; Mon, 21 Feb 2022 22:53:52 -0800 (PST) Received: by mail-pj1-x102a.google.com with SMTP id v8-20020a17090a634800b001bb78857ccdso1470765pjs.1; Mon, 21 Feb 2022 22:53:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cd9N84G12yMFVfK5hwY1Mfhlsjik3wthSQDQX9hRXUk=; b=QsZHvnPM00q1KFr+MDI7WnueUZbQ34onU4GTJ20f+wM2J+G2gGk2cM+59PMI3zkPCq QRnNrb9+zZuLG7lS9EKnY0JQwn717kkyNl5tHxiL0t1mFVn/jzi+MkfbKBnHanzvWfzs Hb+Nk6RhH5Bj/r5dYkzdaeENOLRF16i8A7LShNGTYV+GLK+BdH1KbSAw7247kRAAIZQA vGUEp27VpDw+6wgqmGSJqEl5k0+/sdXVvNhp5PqMmg7nXQuo5dn0fDhXlMiiwl/gScAW 05QhJ9YmWQraaeXjYunyOrS5uj16NN3rQgLac7qEYhuMPj4k39WNRftFdze3d+CrvyCv NjkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cd9N84G12yMFVfK5hwY1Mfhlsjik3wthSQDQX9hRXUk=; b=2qmu+Vt1rBchbq8BGZNtEcU9Hj79urOBLqlE6yD6J3KxXORbf+sR3QfLJkYwCS22WZ iEhn6AqE6DIrwCMF51MkvD1NQiit+GJSEaxFjtzTXlJCe5iFzD2RNKTkJYESusFsMd+m 9FThwdtmYloCGgUoDTaLCGZ7SJ1P32zgUeSDWUIU56qJjmEETmiSokZwgAa9T1+xo+1/ pSeaiUQ+C3LDwmgaJMDJqN4BEY9rlpMNMqSSbuCuQ9yJKVYegzALtJ7dHTgbFY4dSxZi V+XYILy5RIk2uFTN9+RJv3ZZMPOU/NwD2c4EY2uF+SGVS9xxwNB9JRLWYa61uCIrAEl8 MtXg== X-Gm-Message-State: AOAM531gennrbsUM4VXx4RRfRE+xcq7dofIRfzepw+B4SUv76VHAj5+p FoqV69khIezmfh+u1fRwZ0vsNCwheMk= X-Google-Smtp-Source: ABdhPJzBZ/ZuqMSsu1fSF5yxoyHpFwov8SDC/eQY7EC9oneZl9/eBYokReG6uYHSIf+dWE/3Bk44zw== X-Received: by 2002:a17:902:ec83:b0:14f:ba2b:990c with SMTP id x3-20020a170902ec8300b0014fba2b990cmr7867242plg.119.1645512831548; Mon, 21 Feb 2022 22:53:51 -0800 (PST) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:400::5:e2d6]) by smtp.gmail.com with ESMTPSA id t2sm15676094pfg.207.2022.02.21.22.53.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Feb 2022 22:53:51 -0800 (PST) Date: Mon, 21 Feb 2022 22:53:49 -0800 From: Alexei Starovoitov To: Kumar Kartikeya Dwivedi Cc: bpf@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= , Jesper Dangaard Brouer , netfilter-devel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH bpf-next v1 04/15] bpf: Allow storing referenced PTR_TO_BTF_ID in map Message-ID: <20220222065349.ladxy5cqfpdklk3a@ast-mbp.dhcp.thefacebook.com> References: <20220220134813.3411982-1-memxor@gmail.com> <20220220134813.3411982-5-memxor@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220220134813.3411982-5-memxor@gmail.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Sun, Feb 20, 2022 at 07:18:02PM +0530, Kumar Kartikeya Dwivedi wrote: > static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, > int off, int bpf_size, enum bpf_access_type t, > - int value_regno, bool strict_alignment_once) > + int value_regno, bool strict_alignment_once, > + struct bpf_reg_state *atomic_load_reg) No new side effects please. value_regno is not pretty already. At least its known ugliness that we need to clean up one day. > static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn) > { > + struct bpf_reg_state atomic_load_reg; > int load_reg; > int err; > > + __mark_reg_unknown(env, &atomic_load_reg); > + > switch (insn->imm) { > case BPF_ADD: > case BPF_ADD | BPF_FETCH: > @@ -4813,6 +4894,7 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i > else > load_reg = insn->src_reg; > > + atomic_load_reg = *reg_state(env, load_reg); > /* check and record load of old value */ > err = check_reg_arg(env, load_reg, DST_OP); > if (err) > @@ -4825,20 +4907,21 @@ static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_i > } > > /* Check whether we can read the memory, with second call for fetch > - * case to simulate the register fill. > + * case to simulate the register fill, which also triggers checks > + * for manipulation of BTF ID pointers embedded in BPF maps. > */ > err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, > - BPF_SIZE(insn->code), BPF_READ, -1, true); > + BPF_SIZE(insn->code), BPF_READ, -1, true, NULL); > if (!err && load_reg >= 0) > err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, > BPF_SIZE(insn->code), BPF_READ, load_reg, > - true); > + true, load_reg >= 0 ? &atomic_load_reg : NULL); Special xchg logic should be down outside of check_mem_access() instead of hidden by layers of calls.