From patchwork Wed Mar 31 21:27:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12176425 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, 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 5F345C43616 for ; Wed, 31 Mar 2021 21:28:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4140C61075 for ; Wed, 31 Mar 2021 21:28:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230291AbhCaV1e (ORCPT ); Wed, 31 Mar 2021 17:27:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232271AbhCaV12 (ORCPT ); Wed, 31 Mar 2021 17:27:28 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47BC9C06175F for ; Wed, 31 Mar 2021 14:27:28 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id v5so1607727pgj.7 for ; Wed, 31 Mar 2021 14:27:28 -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=bTCEWvQMjkTW/eVBx3Fi28gIb6vhFXkJKuQZd7egWL4=; b=ZyWaDB66yEhpxGUfmbtxVGmU3IBzo+oXxVhHLfWs3XfFFGSmJPLHiE7AtUsL52u4em 7r8+LPrjToiGPIKHfAyX+CYa64laXNc6rI1BGc3zm2kLmapiVVq57hrEGsA6RpFB5njc yJtaF9uxQMIwX5fVhtI6GFkCQjMND6xl8/9j4DypA/x676Betc17fx3372YWMv6uudg1 Uq3pjBGR+txVa6+cTYQpzbIUUhvOP1NbLuj2g77f+DuZDQjxPV7+fKMGDYKtturZq9Sr ladv12DGpbIVZdpLI4mmgcR60wybqF/xda3o7z0Jpt/JICr6LzvTERx4Cld+Z/MhtGVD UuXA== 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=bTCEWvQMjkTW/eVBx3Fi28gIb6vhFXkJKuQZd7egWL4=; b=P4FOkbH1feWxcJKmoC36Ie7JBwCyWqTX9gvoGl5IvmLye8VJh+5BXlx4ssxc6d2h2F rmyU9zCrfD7/ekp5JiqGw0t47MkcksL4L3JGLQ/7OoG23sY8wMx2CgAKnlyrQ0ePsVVQ +0CvWZxOyrYWvUiziEiR+hWRHn3kXPndFUJAnPZ4kd9EoPicJwU0xpZs/ikieDO2OA7m s/iIpw8e0iwheAXVpzqPdx8y2z0qHPjtacANx2c99YxwBRJjM6txQb/ru4+WfrYbVnKN /VT4gYAb1lArYRrpAxBhFGoaGnZcd+BHYyUGNXPCazYSV5B+nrjz9DSs1Smg6Y8vJGlG pGLg== X-Gm-Message-State: AOAM530DsALLOhbn3FDRYcpYVzgff0GToYjGREjWzRZNyiGMmssOXDh9 4sSnELKE2vnHS4ZSk9TR8InSSu24+/KNLBIBptw= X-Google-Smtp-Source: ABdhPJyDPGqZCzSp3WV1/uBjjwnSkHTUJui8hm7KRQKratU0h86QMz9gC7gdr8DJf05TCYSKUV9OwgrvNAHV11IKgX8= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:7933:7015:a5d5:3835]) (user=samitolvanen job=sendgmr) by 2002:a63:d550:: with SMTP id v16mr4986888pgi.164.1617226047699; Wed, 31 Mar 2021 14:27:27 -0700 (PDT) Date: Wed, 31 Mar 2021 14:27:06 -0700 In-Reply-To: <20210331212722.2746212-1-samitolvanen@google.com> Message-Id: <20210331212722.2746212-3-samitolvanen@google.com> Mime-Version: 1.0 References: <20210331212722.2746212-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.291.g576ba9dcdaf-goog Subject: [PATCH v4 02/17] 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 , 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); \ } \