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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 6881ACA9EC9 for ; Fri, 1 Nov 2019 04:00:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BF402083E for ; Fri, 1 Nov 2019 04:00:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="gAic49MA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726229AbfKAEAe (ORCPT ); Fri, 1 Nov 2019 00:00:34 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:43929 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725208AbfKAEAd (ORCPT ); Fri, 1 Nov 2019 00:00:33 -0400 Received: by mail-pg1-f194.google.com with SMTP id l24so5596752pgh.10 for ; Thu, 31 Oct 2019 21:00:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=DqG2K0fvYUAA4E302d2Wr4MEutud0mjKuHdZBEE6NhQ=; b=gAic49MAeOc0RHQwT7q95mZfaWy/E6IhEpBpV5hJ3STSid/jPRu+sGJtzjSfKCXuEf cHqE/dxdIBbercFZyX9sSIjRyybd8IPXMMKNRCD5XgWMmq1WJvMLtGj8wgTBt16jV32H m8Pv3sMDvWULeXDkmLgUa3AZ6LDQXwbzmCxlc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=DqG2K0fvYUAA4E302d2Wr4MEutud0mjKuHdZBEE6NhQ=; b=B+LzgnxB7uLtAFKsVPvIWVyKYhQ6IBN+wiAxWrI422aRDL++Jd0JUssECBkcy6FObf T1Qm4CmbHjoW0DWKKAC2tyeBhTjlroypYmPj091+aKwJXx7xJh8bnQoCawfZAtM5zNAt E372Y+4KnBrChJlZ01BUMmyTRmHcjCl2QWMpdHUlNp6MmFt7jOVCd3BmieleivB5Beex YAsLXUiDiu8K7HZ8Hwa25jNJrpQL0Sd3B95kuui9oMjT7k4Sj8kcq1cISoaf6p5OM4Qz ygxwFWsqoBclfQTl+Q9dmG+GUO3NMvrAKUpof9c7gCTX7iILvXE/FleuH8R98DjRjHR4 dt/w== X-Gm-Message-State: APjAAAVIAcsA3KOf2GucHxbBBHAUlDhXcx2jBAQ0kajhl9QCA5Yg7kUE sQ05/jxkC+BmCProMw2EETLJ+g== X-Google-Smtp-Source: APXvYqwjxz9PkVBJaSe/Y1M2wUY5vJE9zTstT50unKznJW5kGeoF7F85nWGFPaym5lZ0YmXY+dykwQ== X-Received: by 2002:aa7:90da:: with SMTP id k26mr1506175pfk.162.1572580833083; Thu, 31 Oct 2019 21:00:33 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id s15sm6603181pjq.19.2019.10.31.21.00.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Oct 2019 21:00:32 -0700 (PDT) Date: Thu, 31 Oct 2019 21:00:31 -0700 From: Kees Cook To: samitolvanen@google.com Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Laura Abbott , Mark Rutland , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 14/17] arm64: efi: restore x18 if it was corrupted Message-ID: <201910312100.E35C214206@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20191031164637.48901-1-samitolvanen@google.com> <20191031164637.48901-15-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191031164637.48901-15-samitolvanen@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 31, 2019 at 09:46:34AM -0700, samitolvanen@google.com wrote: > If we detect a corrupted x18 and SCS is enabled, restore the register > before jumping back to instrumented code. This is safe, because the > wrapper is called with preemption disabled and a separate shadow stack > is used for interrupt handling. > > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -Kees > --- > arch/arm64/kernel/efi-rt-wrapper.S | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S > index 3fc71106cb2b..945744f16086 100644 > --- a/arch/arm64/kernel/efi-rt-wrapper.S > +++ b/arch/arm64/kernel/efi-rt-wrapper.S > @@ -34,5 +34,10 @@ ENTRY(__efi_rt_asm_wrapper) > ldp x29, x30, [sp], #32 > b.ne 0f > ret > -0: b efi_handle_corrupted_x18 // tail call > +0: > +#ifdef CONFIG_SHADOW_CALL_STACK > + /* Restore x18 before returning to instrumented code. */ > + mov x18, x2 > +#endif > + b efi_handle_corrupted_x18 // tail call > ENDPROC(__efi_rt_asm_wrapper) > -- > 2.24.0.rc0.303.g954a862665-goog > -- Kees Cook