From patchwork Fri Mar 12 00:49:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12133471 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=-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 34ECDC2BA83 for ; Fri, 12 Mar 2021 00:50:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E44264F8D for ; Fri, 12 Mar 2021 00:50:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231615AbhCLAtr (ORCPT ); Thu, 11 Mar 2021 19:49:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231153AbhCLAtZ (ORCPT ); Thu, 11 Mar 2021 19:49:25 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 487C7C061760 for ; Thu, 11 Mar 2021 16:49:25 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id 127so27573335ybc.19 for ; Thu, 11 Mar 2021 16:49:25 -0800 (PST) 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=qBzD2jKlJCBSceSZkOW3qTz3O5z1Bv9x7KfP7hbZayM=; b=Eeipead3OTfdyQVNZR6+I9TFFiFKRPZZrf8vnUFQlgo6+oxt8h0bMJVQroY4XVzr88 Xmv0bF9CGtd2mF8exHl4SSlNBXo0DpAmkhlH2IVxw9yUcbEoH4+5g0wTvB5LB5fKQH6W m3Q7E8EH6Ki8nZVAx0vyozNJyMUQlvD49FWE6zW1ytXmExwv9m0bWZTqeW5iJGLQtkcw XTD5uj2tMYGcL/m4lR1vYJhd9+eVYGGcQ4U98OQn2zQksuRHFvDFFAy33sjrvDfkClva PBfE3juVVgCPKihbF9tklibABTtTIHMyG/09dOJMcteM5eEssVbpGXFNZcJmCXdpqvy9 9R7g== 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=qBzD2jKlJCBSceSZkOW3qTz3O5z1Bv9x7KfP7hbZayM=; b=XZHKTp3u99eyjaGq6XgDMyaZyhKIKuH3UwFc+fSXaSXli4bci7UcuyiiKCw8wH9nly EataukV1X4vIB9TJRatZS/T/BAYdBIzg5aHOJbDaoC6ZCg+w8YCjN7vb/pos11oxLZlR 8sR0I+gCNFgqlEjbvBNYxSHlZ34qAqf3PiW4XRN6M6slXhA6ZtTVbVJ8O6q8NKRY542K 7RaDtRmk8o3nYd/ZIclh4K6/zLv5gFOI2J897JqttJMzaTmcCYBW1C+WQx7YY34nNxzL g7aqZda5C/UE/RTdJ16Lwqy0AGEl8xLZYD3XyqQgjPf0NrNLDxlAFFxQOUmohDusfmSj sl4g== X-Gm-Message-State: AOAM531XsPTBsJ67gr0X5noUi2yKb2BAISvLO+UWjh8oYmFRCQ1UvTtr EY/OVq39pmrA4sHdGWGQ/OYScBFp1NcBYFC6qPo= X-Google-Smtp-Source: ABdhPJxT/RtO93f7gJpAKHqE1/yNm9hIqf4LkKtkGWnA/IVcDAjiGtDBLYlTbUdAeTbLxPSdUndH9TPTNvHjOSf7RVU= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:c86b:8269:af92:55a]) (user=samitolvanen job=sendgmr) by 2002:a25:1485:: with SMTP id 127mr16070777ybu.243.1615510164574; Thu, 11 Mar 2021 16:49:24 -0800 (PST) Date: Thu, 11 Mar 2021 16:49:04 -0800 In-Reply-To: <20210312004919.669614-1-samitolvanen@google.com> Message-Id: <20210312004919.669614-3-samitolvanen@google.com> Mime-Version: 1.0 References: <20210312004919.669614-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH 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 , 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, 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 1ff22bdad992..c275f23ce023 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -57,3 +57,4 @@ #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); \ } \