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,URIBL_BLOCKED, 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 5A5E5C35E01 for ; Tue, 25 Feb 2020 17:40:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C6DD2176D for ; Tue, 25 Feb 2020 17:40:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="B7ASfSbr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731166AbgBYRkM (ORCPT ); Tue, 25 Feb 2020 12:40:12 -0500 Received: from mail-pf1-f202.google.com ([209.85.210.202]:47598 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729510AbgBYRkH (ORCPT ); Tue, 25 Feb 2020 12:40:07 -0500 Received: by mail-pf1-f202.google.com with SMTP id e62so9725669pfh.14 for ; Tue, 25 Feb 2020 09:40:07 -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=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=B7ASfSbr6PJI1PNYuMw4AeQl2rfrBE18p50aZHmoTWWjcghaevDSqsyUvYLaGuvGEV wwBpIUOA2JHt7hx+G+Ornny4GKtz9v4Eypp4NgPZ3xEK3rgMRBRBuNUqNS+ox6ACh+ZC 6cWbkc8+i4jYfG+umapz9k/Bm3qSztOLHJyMg8JMXVQHlKA9VuWwhJw3cIfwhzFXI03b UEh9pcFUZQVWnOG6NbIAR+vAckRKiK94vNJZQ4ldnB79ldCEHyc60gKr6pHwkSc3vVOl SlY8HCGuRiNp4u0S5QuDxi4DnFctp1zaF1wh2WUSCaV9cRZWkMvslEfisyUwfEbN9k+G Kagg== 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=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=kyMNMhztwbU6mou846cQkqQneRsNkC88ndzfRqxJojkN++EUuxnZTVBDQZyk0oiIMI C/iMesNPkgvWejY4QpevrRfX2cT93kJvwwE/IOte3/UVYH9awGPrQd+pXoQ4eqKnh4oR LzUtAT9ByCwtHT7MMwIfVo8DfSpTRgRWe2AsSpti4VwzH/w/sU9KgVvIPQULUgg+jqts fQjEaxGAI0Lg5pbMMN4VpvHdTj3cRB4oCsMJCMaWBRTSHpM4ClSiNTJQBhui1be4TDtP ZlvL9ZTcwvBbwqS+fHha1xcn2cE1c1cGyF1orx7YbzL1g2lBSrm3+AH4AsUiJXL0/lUZ 212A== X-Gm-Message-State: APjAAAXo6Dbwq029BInsFEbnJB3aYnQXOJ85VNNYWQPd+gzzsJpAMh57 EkmLHnzxIcuSFT4ucgMJzCzosfUI3KMnbwvUDpg= X-Google-Smtp-Source: APXvYqw22kkM3bH9wLjSIFkgjo4U46Ik1liYbPY7ppLoTBG5p4rEwIGlGJAnCM7FSLJOm8bUadpuV5p12hkwZ3bHzak= X-Received: by 2002:a63:d244:: with SMTP id t4mr15492036pgi.241.1582652406574; Tue, 25 Feb 2020 09:40:06 -0800 (PST) Date: Tue, 25 Feb 2020 09:39:28 -0800 In-Reply-To: <20200225173933.74818-1-samitolvanen@google.com> Message-Id: <20200225173933.74818-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200225173933.74818-1-samitolvanen@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v9 07/12] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , James Morse , 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, restore the register before jumping back to potentially SCS 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 Acked-by: Will Deacon --- 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..6ca6c0dc11a1 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: + /* + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a + * shadow stack pointer, which we need to restore before returning to + * potentially 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 + b efi_handle_corrupted_x18 // tail call ENDPROC(__efi_rt_asm_wrapper) -- 2.25.0.265.gbab2e86ba0-goog