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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 B37D1C43603 for ; Fri, 6 Dec 2019 22:14:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86FAE206DB for ; Fri, 6 Dec 2019 22:14:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="c1Wx0pmg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726801AbfLFWO1 (ORCPT ); Fri, 6 Dec 2019 17:14:27 -0500 Received: from mail-qv1-f74.google.com ([209.85.219.74]:36402 "EHLO mail-qv1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726755AbfLFWOZ (ORCPT ); Fri, 6 Dec 2019 17:14:25 -0500 Received: by mail-qv1-f74.google.com with SMTP id r8so764467qvp.3 for ; Fri, 06 Dec 2019 14:14:24 -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=FhYYEjTDkPuKHbZnKePlOaf9pf8CUWO3nD3sOS+po+M=; b=c1Wx0pmgZzJDLcr5nKIxS6pdb72MNBZXygUHxUgHfIREUjivSfJmFNkd4nH821+c7c XdMpdHUqSUmAmYnv/wYcSmRCYqJtUh+jdTQ3/0TYFxbvGCg3KubysunPGfqG0BjN6R5p FZYsTRty1KKiwCF3GFPmHDSfqSVDKBB9Dl9Svv8Esh85iZQ6Gp8IldBOuKDVG0NAYrct KCNN1c4Jt5Qnd9QE5BIqwUiELeUVYdQWv32ArtiqQbBLSzZpaS8483/PTd49tfr3IpbZ ZlBwyqxJM8pdiJ2dTz9waDv/2F+kWZdAUGGPKaihus1bQ20pRuQajRsHhJifC3dGS/Vz k2Wg== 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=FhYYEjTDkPuKHbZnKePlOaf9pf8CUWO3nD3sOS+po+M=; b=N2cUY7Wp//m09h+MzwlnHTL0hygXJnpMpx2DJNKtCdwhe/KnKpdsUWfZFoPsvOq5I8 JXUb/T/rlPkMwFWZTSUZCnL9KsZ6xG8eWfNutvZ66H+GeeRkLyOG3WQMUqafrmkseSaZ SmreTujOvkPQBOYA6B6+USHCmJ/2BZYe0W/DUMc524P+i5/hUSiH6+XwEKKsn2tyfTif 6vmratKmnrje/S7fIvwrOKO740mF83DvjGakcsc3JuQGwE5/zPYI4ZTMlRHuYOqZ5L3s qIE3VqYobuJ6opFDj55QAT7rIQohvvD6svZRmkqxHd38L2WX430npdAPTKrcQ8KBuIyB GMlg== X-Gm-Message-State: APjAAAVg24zoLLZfHWk3wFt9a/J/t9N/Ckzw9jAUTIkyaSCwre7xvnvJ yYNrBcqD/LMsacFN06TqnAVpur6t02yijg/7va0= X-Google-Smtp-Source: APXvYqwZLBeooXOHcOO29WvEdpgbxookvNvj944sJ15kbZCCqA2Ea8mnulB5DEVBZW8wLWpSg85W/yQRRXH7nkmyS6o= X-Received: by 2002:ac8:2201:: with SMTP id o1mr15071384qto.247.1575670464028; Fri, 06 Dec 2019 14:14:24 -0800 (PST) Date: Fri, 6 Dec 2019 14:13:47 -0800 In-Reply-To: <20191206221351.38241-1-samitolvanen@google.com> Message-Id: <20191206221351.38241-12-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191206221351.38241-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.393.g34dc348eaf-goog Subject: [PATCH v6 11/15] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , 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, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S index 3fc71106cb2b..62f0260f5c17 100644 --- a/arch/arm64/kernel/efi-rt-wrapper.S +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -34,5 +34,14 @@ 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. This is + * safe because the wrapper is called with preemption disabled and + * a separate shadow stack is used for interrupts. + */ + mov x18, x2 +#endif + b efi_handle_corrupted_x18 // tail call ENDPROC(__efi_rt_asm_wrapper) -- 2.24.0.393.g34dc348eaf-goog