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 2DFF4EB64D9 for ; Mon, 26 Jun 2023 18:43:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232553AbjFZSnA (ORCPT ); Mon, 26 Jun 2023 14:43:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232577AbjFZSmw (ORCPT ); Mon, 26 Jun 2023 14:42:52 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BAB21BE4 for ; Mon, 26 Jun 2023 11:42:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E648860F30 for ; Mon, 26 Jun 2023 18:42:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F07B5C433C0; Mon, 26 Jun 2023 18:42:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687804957; bh=VdPFga4rnB6NZ0tvz8CkuH0HU59xV7PCi3TcVEes/Wo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EmbneaOaLDF9jdltsB5FW3s79v/yFaL+3xFH9ObCatgkNcBPG02UchWf3EbYm53Gi IVvbACSHlco2JrkoDZzfvVB2gEjRgfhOrRcCB2USuN4k09W+8uOZU6xT+2C6EJxIBZ nZ1jG3Qof+je7q8QUyKdjId8ZlFF/YnjrHMAmYfs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Florent Revest , Daniel Borkmann , Andrii Nakryiko , Yonghong Song , Nick Desaulniers , Sasha Levin Subject: [PATCH 5.15 70/96] bpf/btf: Accept function names that contain dots Date: Mon, 26 Jun 2023 20:12:25 +0200 Message-ID: <20230626180749.868128588@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230626180746.943455203@linuxfoundation.org> References: <20230626180746.943455203@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Florent Revest [ Upstream commit 9724160b3942b0a967b91a59f81da5593f28b8ba ] When building a kernel with LLVM=1, LLVM_IAS=0 and CONFIG_KASAN=y, LLVM leaves DWARF tags for the "asan.module_ctor" & co symbols. In turn, pahole creates BTF_KIND_FUNC entries for these and this makes the BTF metadata validation fail because they contain a dot. In a dramatic turn of event, this BTF verification failure can cause the netfilter_bpf initialization to fail, causing netfilter_core to free the netfilter_helper hashmap and netfilter_ftp to trigger a use-after-free. The risk of u-a-f in netfilter will be addressed separately but the existence of "asan.module_ctor" debug info under some build conditions sounds like a good enough reason to accept functions that contain dots in BTF. Although using only LLVM=1 is the recommended way to compile clang-based kernels, users can certainly do LLVM=1, LLVM_IAS=0 as well and we still try to support that combination according to Nick. To clarify: - > v5.10 kernel, LLVM=1 (LLVM_IAS=0 is not the default) is recommended, but user can still have LLVM=1, LLVM_IAS=0 to trigger the issue - <= 5.10 kernel, LLVM=1 (LLVM_IAS=0 is the default) is recommended in which case GNU as will be used Fixes: 1dc92851849c ("bpf: kernel side support for BTF Var and DataSec") Signed-off-by: Florent Revest Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Cc: Yonghong Song Cc: Nick Desaulniers Link: https://lore.kernel.org/bpf/20230615145607.3469985-1-revest@chromium.org Signed-off-by: Sasha Levin --- kernel/bpf/btf.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6c7126de5c17f..5d4bea53ac1f8 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -633,13 +633,12 @@ static bool btf_name_offset_valid(const struct btf *btf, u32 offset) return offset < btf->hdr.str_len; } -static bool __btf_name_char_ok(char c, bool first, bool dot_ok) +static bool __btf_name_char_ok(char c, bool first) { if ((first ? !isalpha(c) : !isalnum(c)) && c != '_' && - ((c == '.' && !dot_ok) || - c != '.')) + c != '.') return false; return true; } @@ -656,20 +655,20 @@ static const char *btf_str_by_offset(const struct btf *btf, u32 offset) return NULL; } -static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok) +static bool __btf_name_valid(const struct btf *btf, u32 offset) { /* offset must be valid */ const char *src = btf_str_by_offset(btf, offset); const char *src_limit; - if (!__btf_name_char_ok(*src, true, dot_ok)) + if (!__btf_name_char_ok(*src, true)) return false; /* set a limit on identifier length */ src_limit = src + KSYM_NAME_LEN; src++; while (*src && src < src_limit) { - if (!__btf_name_char_ok(*src, false, dot_ok)) + if (!__btf_name_char_ok(*src, false)) return false; src++; } @@ -677,17 +676,14 @@ static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok) return !*src; } -/* Only C-style identifier is permitted. This can be relaxed if - * necessary. - */ static bool btf_name_valid_identifier(const struct btf *btf, u32 offset) { - return __btf_name_valid(btf, offset, false); + return __btf_name_valid(btf, offset); } static bool btf_name_valid_section(const struct btf *btf, u32 offset) { - return __btf_name_valid(btf, offset, true); + return __btf_name_valid(btf, offset); } static const char *__btf_name_by_offset(const struct btf *btf, u32 offset) @@ -3536,7 +3532,7 @@ static s32 btf_var_check_meta(struct btf_verifier_env *env, } if (!t->name_off || - !__btf_name_valid(env->btf, t->name_off, true)) { + !__btf_name_valid(env->btf, t->name_off)) { btf_verifier_log_type(env, t, "Invalid name"); return -EINVAL; } -- 2.39.2