From patchwork Fri Aug 21 10:29:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenz Bauer X-Patchwork-Id: 1349042 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=cloudflare.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=cloudflare.com header.i=@cloudflare.com header.a=rsa-sha256 header.s=google header.b=JCLUg5q3; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BXyV11MQTz9sTF for ; Fri, 21 Aug 2020 20:31:05 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728478AbgHUKbE (ORCPT ); Fri, 21 Aug 2020 06:31:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728593AbgHUKaT (ORCPT ); Fri, 21 Aug 2020 06:30:19 -0400 Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5BE2C06134A for ; Fri, 21 Aug 2020 03:30:15 -0700 (PDT) Received: by mail-wr1-x441.google.com with SMTP id z18so1435657wrm.12 for ; Fri, 21 Aug 2020 03:30:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=xrkad1dT1PqnIAHvf/9uKqIEtr9fqQIFC7z/xBajrtk=; b=JCLUg5q3TNl+zUrInUVsJb9rfRTarwsabzIEn4Tk/CwtmbS/lp3Ou6S1BfWrBAUTJ7 fws8rOT5/BjFv0fYuXRPPRRIlHmY3Un0j0LVVLnLcP2cEbTHgobtoDWS6tB0dXEQub8S z4XoKPVmyjyx5YlR9mxAGJYliSpvHRSmBlMXk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=xrkad1dT1PqnIAHvf/9uKqIEtr9fqQIFC7z/xBajrtk=; b=NM1PQ4fKn8gXCBZi9OboLxBcFJ5viwLBNxLsSVdU8Wo6xnZRzDxnd9dasjlPJpEWYN Ca7QsgoztnTOHguuzXkEZu5jzbEBGDNUl52lkkj4qbJGAVp9bwfYBWZm0FXTHh0LoJbC znxKjYAPWIr46bKnhw8wUZtu5+JRJJVAH2My04GtRvOCki2VkjGHhAopFHAtLYbUdvST ujReEk4pqef5Hkm8D5s45De5R0JWvOlJvSKyJYAVcghJpc2PHGwnX68DgFyj/5QBJ2lp Nac3KjObBzrGcdM1+PRaMd8aRIyvCriTJj/Kuri48E112sobfe0DD25Wq3BCB+3/EZHo ldpQ== X-Gm-Message-State: AOAM5321wSDbviWwKkG63M9zkUGxpDiXxSd/gexujnfoLmebCywqmGfc SzZisbpO5KHpvotDtXJG4jFDTg== X-Google-Smtp-Source: ABdhPJzMynC4jfB4bnwwHan1D1AwRLftCS/eM+XLyQgRESI8PGz2Tg30nghCyVNW+ktKMZ6yhs3F0Q== X-Received: by 2002:adf:efcc:: with SMTP id i12mr2169405wrp.308.1598005814012; Fri, 21 Aug 2020 03:30:14 -0700 (PDT) Received: from antares.lan (2.2.9.a.d.9.4.f.6.1.8.9.f.9.8.5.f.f.6.2.a.5.a.7.0.b.8.0.1.0.0.2.ip6.arpa. [2001:8b0:7a5a:26ff:589f:9816:f49d:a922]) by smtp.gmail.com with ESMTPSA id o2sm3296885wrj.21.2020.08.21.03.30.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Aug 2020 03:30:13 -0700 (PDT) From: Lorenz Bauer To: jakub@cloudflare.com, john.fastabend@gmail.com, yhs@fb.com, Alexei Starovoitov , Daniel Borkmann Cc: kernel-team@cloudflare.com, Lorenz Bauer , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v3 4/6] bpf: override the meaning of ARG_PTR_TO_MAP_VALUE for sockmap and sockhash Date: Fri, 21 Aug 2020 11:29:46 +0100 Message-Id: <20200821102948.21918-5-lmb@cloudflare.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200821102948.21918-1-lmb@cloudflare.com> References: <20200821102948.21918-1-lmb@cloudflare.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org The verifier assumes that map values are simple blobs of memory, and therefore treats ARG_PTR_TO_MAP_VALUE, etc. as such. However, there are map types where this isn't true. For example, sockmap and sockhash store sockets. In general this isn't a big problem: we can just write helpers that explicitly requests PTR_TO_SOCKET instead of ARG_PTR_TO_MAP_VALUE. The one exception are the standard map helpers like map_update_elem, map_lookup_elem, etc. Here it would be nice we could overload the function prototype for different kinds of maps. Unfortunately, this isn't entirely straight forward: We only know the type of the map once we have resolved meta->map_ptr in check_func_arg. This means we can't swap out the prototype in check_helper_call until we're half way through the function. Instead, modify check_func_arg to treat ARG_PTR_TO_MAP_VALUE to mean "the native type for the map" instead of "pointer to memory" for sockmap and sockhash. This means we don't have to modify the function prototype at all Signed-off-by: Lorenz Bauer Acked-by: Yonghong Song --- kernel/bpf/verifier.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b6ccfce3bf4c..7e15866c5184 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3872,6 +3872,33 @@ static int int_ptr_type_to_size(enum bpf_arg_type type) return -EINVAL; } +static int resolve_map_arg_type(struct bpf_verifier_env *env, + const struct bpf_call_arg_meta *meta, + enum bpf_arg_type *arg_type) +{ + if (!meta->map_ptr) { + /* kernel subsystem misconfigured verifier */ + verbose(env, "invalid map_ptr to access map->type\n"); + return -EACCES; + } + + switch (meta->map_ptr->map_type) { + case BPF_MAP_TYPE_SOCKMAP: + case BPF_MAP_TYPE_SOCKHASH: + if (*arg_type == ARG_PTR_TO_MAP_VALUE) { + *arg_type = ARG_PTR_TO_SOCKET; + } else { + verbose(env, "invalid arg_type for sockmap/sockhash\n"); + return -EINVAL; + } + break; + + default: + break; + } + return 0; +} + static int check_func_arg(struct bpf_verifier_env *env, u32 arg, struct bpf_call_arg_meta *meta, const struct bpf_func_proto *fn) @@ -3904,6 +3931,14 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, return -EACCES; } + if (arg_type == ARG_PTR_TO_MAP_VALUE || + arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || + arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { + err = resolve_map_arg_type(env, meta, &arg_type); + if (err) + return err; + } + if (arg_type == ARG_PTR_TO_MAP_KEY || arg_type == ARG_PTR_TO_MAP_VALUE || arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE ||