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 X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 75340C433DB for ; Thu, 18 Mar 2021 17:51:23 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 132D664F1C for ; Thu, 18 Mar 2021 17:51:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 132D664F1C Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From:In-Reply-To: References:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MyuNmLSRHuSkn+VJr2Ocb2jUedhJl3McB0aA7trFuQY=; b=DDR5/UnbTG9lGI9sei8jcccFa 0VFOgXns9N4cH70ZhBa2Uw/Qen4en+2xxDwDvREwDFT72ivSkN55HCgl+QrM9byG42xnPOI7fkUI0 Bwfr700ADcnXEYsTMXLdCmEIt8m5/ha2GUhnVvkJshkdyRsY87PAQByPjUdTefH6YUgDRlCiIPtOF KS1CPmSuDJiimk5ZtlMaQ23B8HrRbjHNBCWwSFzHKKi3pQPssrWA3yhZgu/BWeaOR7guu/NCQCoPz ph0SzYJpZ2fvx+clAnRnQv/j3GrimiZbrzYGui4oOVpTg9Px2YZzOst6r4c9jXofFVDVLVzE38dTI TQbt4D0sg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lMwmd-005mJZ-0T; Thu, 18 Mar 2021 17:50:07 +0000 Received: from mail-lf1-x134.google.com ([2a00:1450:4864:20::134]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lMwmZ-005mJF-UU for linux-arm-kernel@lists.infradead.org; Thu, 18 Mar 2021 17:50:05 +0000 Received: by mail-lf1-x134.google.com with SMTP id a198so5935673lfd.7 for ; Thu, 18 Mar 2021 10:50:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rnxu0Htej1H516ep79Wgi7n3VX+5maU9JLJNzsCgiUM=; b=Ni7pji1XH63Bsx+pQeydcoFnVFUKTo4EK8YEo+eRY0n8Z2OlAnJtkVrPBHxbEsi1+R +o0D2M9JZb3tGqGl8p3T5U+v1MyYLTUUMRcgkL4iuhrlTfi3bi87ds7MxG2e3n0KlK6i 3dJiohcmgFoCgox4RNZsf0OK7goEnUFKbgGqAAdLekm/+D9U6DNU7jqJvakwMwfDAFa4 v8f//XFUMtHrMKaTRuIfAgjuRPu2++XBnBmKfeuHtrLLgiyJIOsF+rgRl3qxfjWKRupz HuO8O/BYYDPWXJdD72MiPYs06QEHnux8aIOk5Nz61Niw4ufVgh0Hi+g9U0GNCsttzUhd wMtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rnxu0Htej1H516ep79Wgi7n3VX+5maU9JLJNzsCgiUM=; b=GO97HFDmAId6/Byan9m875A3TEVykoP3UD0TLEM6vm/LP553OM8F9t15+44Jv3GPmR ka/pfJmU6fzqyn60TCJIyHBUk9QLQse9mloQXCoPRWxzTPG0KD4k7EzsH3D7oRd+URk1 X+g9eZuR8MrQcyUloXpCVbzBPc7hiH1KEEgTWx7b7Vm+BiR69iy3yTDZPQiKqfPvYvD2 iUInf/5FUj5RpEVKBATPwHRA9WXnXbgkCf+KSpzT/24WMwyl7VZz/UazDiBmeb9Wu7l/ Ro7evYB4Mc0exZfw4a96iNPHVRuIt9z0JpMH2TneEAQDNZq0ueeiidtSAUixQ01ZS4lq Z9qA== X-Gm-Message-State: AOAM533QF1HohWbeTnq8WjmVyzcWksunqjJ0Er0u8725rIAuEAOWaaHX PNP2oV7152EmIrQBeaRen37v9XMcm84hlLh2t77rCA== X-Google-Smtp-Source: ABdhPJwKRBRM7MAUZwFeZ179486WWfFrS/ksEmFI/VqMTZ8H+kaaJb/iKuGQiKzYL2s45rV0vHLFMREgPO6HFTWGKDo= X-Received: by 2002:a05:6512:985:: with SMTP id w5mr5887489lft.122.1616089801932; Thu, 18 Mar 2021 10:50:01 -0700 (PDT) MIME-Version: 1.0 References: <20210318171111.706303-1-samitolvanen@google.com> <20210318171111.706303-3-samitolvanen@google.com> In-Reply-To: <20210318171111.706303-3-samitolvanen@google.com> From: Nick Desaulniers Date: Thu, 18 Mar 2021 10:49:50 -0700 Message-ID: Subject: Re: [PATCH v2 02/17] cfi: add __cficanonical To: Sami Tolvanen Cc: Kees Cook , Nathan Chancellor , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , bpf , linux-hardening@vger.kernel.org, linux-arch , Linux ARM , Linux Kbuild mailing list , PCI , LKML X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210318_175004_106985_3BD2411E X-CRM114-Status: GOOD ( 29.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen wrote: > > 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 Irrelevant to this series, but I checked when the FN attr was first available in clang; clang-10. (That's the minimum supported version of clang for the kernel, and this series depends on LTO which depends on clang-12, so no additional guards are necessary). Reviewed-by: Nick Desaulniers > --- > 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); \ > } \ > -- > 2.31.0.291.g576ba9dcdaf-goog > -- Thanks, ~Nick Desaulniers _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel