From patchwork Wed Mar 10 22:02:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florent Revest X-Patchwork-Id: 12129583 X-Patchwork-Delegate: bpf@iogearbox.net 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=-19.0 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 0FF89C43381 for ; Wed, 10 Mar 2021 22:03:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D804A64FD8 for ; Wed, 10 Mar 2021 22:03:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233770AbhCJWDP (ORCPT ); Wed, 10 Mar 2021 17:03:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234372AbhCJWCw (ORCPT ); Wed, 10 Mar 2021 17:02:52 -0500 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79729C061761 for ; Wed, 10 Mar 2021 14:02:29 -0800 (PST) Received: by mail-wm1-x32b.google.com with SMTP id y124-20020a1c32820000b029010c93864955so11990655wmy.5 for ; Wed, 10 Mar 2021 14:02:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=QHAXRp5cjvFe5tOwLQufuvHj4q8NvqNGvXDx3zXkaA4=; b=U6+Nq610gcxHKdFeY47vS8PPCzFV27nnVAtzLR5quvgbjkblFoy39EvLscG8l+5OW2 7kmeEhaSLd7HWtOv4Bbb8LUN1Lsr83xGKQbtgJ8Xj/vfC2bMF/33OBQwV63KKhSPsKXJ zOinN93ztMiP14oQrofxLGxVNBg6u1IZEXQxY= 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=QHAXRp5cjvFe5tOwLQufuvHj4q8NvqNGvXDx3zXkaA4=; b=HYSQSgfvM82z/xsycu6P2K4waMZVczsVc5tiLPKIq2wH2Wc+hXRqe4CYklBVvK0n33 mnuYVG1U9lU7f5ihqz6RyfQX0Wgsk1srVcudjY+F6Q0htoq3nl5rcoudXQYmBBjrS0VG ghNItYK0ENYJwNxJO/gLDF82IwO97HhTOjvcbWdW01i06/jIZoj9W0EzdrVdT90QEqvJ /IAHgDYATV9JkwVHRAiM0vKPniDaNCTQypfBpoo8MUCKH0fPNytLvMjM+aYPD+NTjgm8 iclfrwGqMUjTZIhky2qluLyuSuaiPvVNw2EKZGX4au6NkXsT5yBDBfj6LqHvTuYF+X4x lTUw== X-Gm-Message-State: AOAM533IaQW6hxExxuzs6E+/UrYbW/pP0DD3dHsnOknjEHV7B7zjZQWm 7LweCKdX8jYYUDLDd5cYADyy1gJgfeRvpA== X-Google-Smtp-Source: ABdhPJzpWpebzf0c61H/lJ2zQRw60kkX/cWWJoDKfBhbV797QkHfXd98E21ocytgVprI4DCdLyjfuw== X-Received: by 2002:a1c:2857:: with SMTP id o84mr5238166wmo.181.1615413747789; Wed, 10 Mar 2021 14:02:27 -0800 (PST) Received: from revest.zrh.corp.google.com ([2a00:79e0:42:204:e08c:1e90:4e6b:365a]) by smtp.gmail.com with ESMTPSA id y16sm699234wrh.3.2021.03.10.14.02.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Mar 2021 14:02:27 -0800 (PST) From: Florent Revest To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, yhs@fb.com, kpsingh@kernel.org, jackmanb@chromium.org, linux-kernel@vger.kernel.org, Florent Revest Subject: [PATCH bpf-next 1/5] bpf: Add a ARG_PTR_TO_CONST_STR argument type Date: Wed, 10 Mar 2021 23:02:07 +0100 Message-Id: <20210310220211.1454516-2-revest@chromium.org> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog In-Reply-To: <20210310220211.1454516-1-revest@chromium.org> References: <20210310220211.1454516-1-revest@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This type provides the guarantee that an argument is going to be a const pointer to somewhere in a read-only map value. It also checks that this pointer is followed by a NULL character before the end of the map value. Signed-off-by: Florent Revest Reported-by: kernel test robot Reported-by: kernel test robot --- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a25730eaa148..7b5319d75b3e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -308,6 +308,7 @@ enum bpf_arg_type { ARG_PTR_TO_PERCPU_BTF_ID, /* pointer to in-kernel percpu type */ ARG_PTR_TO_FUNC, /* pointer to a bpf program function */ ARG_PTR_TO_STACK_OR_NULL, /* pointer to stack or NULL */ + ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */ __BPF_ARG_TYPE_MAX, }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f9096b049cd6..c99b2b67dc8d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4601,6 +4601,7 @@ static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALU static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_PERCPU_BTF_ID } }; static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; +static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } }; static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_MAP_KEY] = &map_key_value_types, @@ -4631,6 +4632,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = { [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types, [ARG_PTR_TO_FUNC] = &func_ptr_types, [ARG_PTR_TO_STACK_OR_NULL] = &stack_ptr_types, + [ARG_PTR_TO_CONST_STR] = &const_str_ptr_types, }; static int check_reg_type(struct bpf_verifier_env *env, u32 regno, @@ -4881,6 +4883,45 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, if (err) return err; err = check_ptr_alignment(env, reg, 0, size, true); + } else if (arg_type == ARG_PTR_TO_CONST_STR) { + struct bpf_map *map = reg->map_ptr; + int map_off, i; + u64 map_addr; + char *map_ptr; + + if (!map || !bpf_map_is_rdonly(map)) { + verbose(env, "R%d does not point to a readonly map'\n", regno); + return -EACCES; + } + + if (!tnum_is_const(reg->var_off)) { + verbose(env, "R%d is not a constant address'\n", regno); + return -EACCES; + } + + if (!map->ops->map_direct_value_addr) { + verbose(env, "no direct value access support for this map type\n"); + return -EACCES; + } + + err = check_helper_mem_access(env, regno, + map->value_size - reg->off, + false, meta); + if (err) + return err; + + map_off = reg->off + reg->var_off.value; + err = map->ops->map_direct_value_addr(map, &map_addr, map_off); + if (err) + return err; + + map_ptr = (char *)(map_addr); + for (i = map_off; map_ptr[i] != '\0'; i++) { + if (i == map->value_size - 1) { + verbose(env, "map does not contain a NULL-terminated string\n"); + return -EACCES; + } + } } return err;