From patchwork Thu Apr 1 23:32:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12179923 X-Patchwork-Delegate: kuba@kernel.org 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, 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,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 8F6EAC4360C for ; Thu, 1 Apr 2021 23:32:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6690861130 for ; Thu, 1 Apr 2021 23:32:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235711AbhDAXc0 (ORCPT ); Thu, 1 Apr 2021 19:32:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235912AbhDAXcZ (ORCPT ); Thu, 1 Apr 2021 19:32:25 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC1D7C0613A8 for ; Thu, 1 Apr 2021 16:32:22 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id p12so3659094plw.0 for ; Thu, 01 Apr 2021 16:32:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=UueCb+prJKWXLp5VR3fqk5CXQc0Ab5GgzQzu/xo2P9E=; b=YgEJwWoldHoDIKiiF7PoeaO8mKT/D1SC1mTBCW9jcHft8TDOoFkoTFE/n/qTe4cHzS FztWbduBQ23TJLiO+mu///7uMJY+YT6crA5fpe7E11aMdWdQbvQKLPnIA/prLfkdJsoD /gLPPkiVdX1e5JHp1IfygeNMt+vsf5l6xHjyi+MeJ3Gd/zp9xSBVOqrBTkESVBrWVPi5 p6zsc1zF1OPOrGKhTIeaqp1Bo0ntss5/i03JAhypbGIvFWF+QSdyx/QTUK0iJYg5og0v bBK53xcbRUcpRHI6NdfegG+ozN4YNkjRHX89w9/GRXhoQFxsv6cJ+xMRfKc66Ll3i4eY k2mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=UueCb+prJKWXLp5VR3fqk5CXQc0Ab5GgzQzu/xo2P9E=; b=AuZ8Y7bkf4jDr+4mieW3FdkMRD4dssAHSBTZ++bDO7nVwB6BpdvPOaoaGQHQDQnCeu /gaywzBDOA9fScHpxeBB5DYniCxX+U/eE2C+X24ptqpC28+nQwl0JnHoj8NMeD+OK3lU N7zqUFPOJntYZXSxCuNpjtjQCirybSdmPEgih80azfyaZHSj7S6HllznGYbK8S20omIe xR+qnCNSE/Or0xT+1Pk5ephnL6UlvC7RKyL4UgYIzlrjaHwUsD61/RjRzSR6KED8brsH 3hY9AMiEXtkdwxU58soqk6TEJqqPEK8a46XbmifNNCM9ljAbPumJWq1XhFGx8Hwe9Z0w EkZg== X-Gm-Message-State: AOAM533FHDi0UD0EZsCCJpv/jblBNXPKyEuQyvNaw99SkgB18oMRHO6o yABiUCaeNM4SEeQDqAYthRIqwwykXnsxrSsCTRc= X-Google-Smtp-Source: ABdhPJwxduIri2IKJBaAY8ilTJfPwgodBRJfhWjsSvt8WBSIvP9IkLfHwtarDxMGAwPZXg2+pGsTEU0CI9ZmvdZhNMc= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:4cd1:da86:e91b:70b4]) (user=samitolvanen job=sendgmr) by 2002:a17:90a:ba05:: with SMTP id s5mr11390928pjr.194.1617319942329; Thu, 01 Apr 2021 16:32:22 -0700 (PDT) Date: Thu, 1 Apr 2021 16:32:00 -0700 In-Reply-To: <20210401233216.2540591-1-samitolvanen@google.com> Message-Id: <20210401233216.2540591-3-samitolvanen@google.com> Mime-Version: 1.0 References: <20210401233216.2540591-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.208.g409f899ff0-goog Subject: [PATCH v5 02/18] cfi: add __cficanonical From: Sami Tolvanen To: Kees Cook Cc: Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , Peter Zijlstra , Sedat Dilek , Mark Rutland , Catalin Marinas , bpf@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org With CONFIG_CFI_CLANG, the compiler replaces a function address taken in C code with the address of a local jump table entry, which passes runtime indirect call checks. However, the compiler won't replace addresses taken in assembly code, which will result in a CFI failure if we later jump to such an address in instrumented C code. The code generated for the non-canonical jump table looks this: : /* In C, &noncanonical points here */ jmp noncanonical ... : /* function body */ ... This change adds the __cficanonical attribute, which tells the compiler to use a canonical jump table for the function instead. This means the compiler will rename the actual function to .cfi and points the original symbol to the jump table entry instead: : /* jump table entry */ jmp canonical.cfi ... : /* function body */ ... As a result, the address taken in assembly, or other non-instrumented code always points to the jump table and therefore, can be used for indirect calls in instrumented code without tripping CFI checks. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Bjorn Helgaas # pci.h --- include/linux/compiler-clang.h | 1 + include/linux/compiler_types.h | 4 ++++ include/linux/init.h | 4 ++-- include/linux/pci.h | 4 ++-- 4 files changed, 9 insertions(+), 4 deletions(-) diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 6de9d0c9377e..adbe76b203e2 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -63,3 +63,4 @@ #endif #define __nocfi __attribute__((__no_sanitize__("cfi"))) +#define __cficanonical __attribute__((__cfi_canonical_jump_table__)) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 796935a37e37..d29bda7f6ebd 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -246,6 +246,10 @@ struct ftrace_likely_data { # define __nocfi #endif +#ifndef __cficanonical +# define __cficanonical +#endif + #ifndef asm_volatile_goto #define asm_volatile_goto(x...) asm goto(x) #endif diff --git a/include/linux/init.h b/include/linux/init.h index b3ea15348fbd..045ad1650ed1 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -220,8 +220,8 @@ extern bool initcall_debug; __initcall_name(initstub, __iid, id) #define __define_initcall_stub(__stub, fn) \ - int __init __stub(void); \ - int __init __stub(void) \ + int __init __cficanonical __stub(void); \ + int __init __cficanonical __stub(void) \ { \ return fn(); \ } \ diff --git a/include/linux/pci.h b/include/linux/pci.h index 86c799c97b77..39684b72db91 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1944,8 +1944,8 @@ enum pci_fixup_pass { #ifdef CONFIG_LTO_CLANG #define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ class_shift, hook, stub) \ - void stub(struct pci_dev *dev); \ - void stub(struct pci_dev *dev) \ + void __cficanonical stub(struct pci_dev *dev); \ + void __cficanonical stub(struct pci_dev *dev) \ { \ hook(dev); \ } \