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 84AFFC2BB55 for ; Thu, 16 Apr 2020 16:13:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D9C82223F for ; Thu, 16 Apr 2020 16:13:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PfLQtJvA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2506898AbgDPQNS (ORCPT ); Thu, 16 Apr 2020 12:13:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2506867AbgDPQNI (ORCPT ); Thu, 16 Apr 2020 12:13:08 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 15881C0610D5 for ; Thu, 16 Apr 2020 09:13:07 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id f11so3464413pfq.2 for ; Thu, 16 Apr 2020 09:13:07 -0700 (PDT) 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=ir6AMcU/LNJfVmH7TAbfuSTmLjnaQbzCZFrLbu9sicg=; b=PfLQtJvAzz5yI91olwSgmzdmwgdtJxdSpUwDBUqAfM/Qj4X8PTnr8pe6M1E9q+SxMQ 9DuGyRyHutXrki59bdmwIERRsNZo12qtXtT7YTGaQUvErlBRD5mI0A9o3BWgwYogesFw pJQazMuF7VSg8nXXNbbuwnalk1A8GI2siOE+gzAVLDi5SEfj4qBjBhPGSFAFigx0XT27 2J6qu4mUgNZPuqq+yi7V5b3R7FRrHRFEL+uzZRZfJJCkuZ3Y9YcoQ6IkCgna/0CQ22Jg qGjnRtJiwEZAIC0v5v+CcPVf8e5pwqpO5XgzgToKbUlUPQ54YIcNjAxSzrtDUK8hBIAD 0GIQ== 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=ir6AMcU/LNJfVmH7TAbfuSTmLjnaQbzCZFrLbu9sicg=; b=rrCgakQJHmi0M4Ukg260Wxa7cL8Ae+7/W1PJSvTQkPvUH0kvQCnBBp+3PelBVrKh7y PLXZeidJEGJ60CXIoCjjSBm0ER4Wrmo4eraO1X8iWLSLlW44ihHJnkJ7gpzKQpXV1EXj TobHANAEmzk0scIfk2SnMG5U1tmLK9lOi7DZOuFJJEzefV0D34FGJtmd2CyW+2XAVfWR mcXoJCPQVTc5CtHlFzPa/DwQdxiKZXoE/3vqQx7yQgKU04fleWYCC0TLCRVwHiqcFnw6 8av0xCbHojPJ8tq1HIYoyPnleAj2OnWJePol5u+T+OedfkSxiGch75ovg1bs4K48Me33 0qFw== X-Gm-Message-State: AGi0PuYm7AO7HuBP9n/dTxFM1Kfj8XkWLyypkNP9BpUMlN4udhVY0ggI OQjXVLCkRdlNoHPoDY5kiiKPuvpeaS3WbHxobO8= X-Google-Smtp-Source: APiQypLtd8ftrhqgq/6RnJ5qnFSnfzNaIUqdmQcwCsxZfxvN3FzC3GYwf1kFiAS1IaIXQEFXlhjHe+bl82oElgHqTYg= X-Received: by 2002:a17:90a:cc10:: with SMTP id b16mr5944791pju.29.1587053586616; Thu, 16 Apr 2020 09:13:06 -0700 (PDT) Date: Thu, 16 Apr 2020 09:12:40 -0700 In-Reply-To: <20200416161245.148813-1-samitolvanen@google.com> Message-Id: <20200416161245.148813-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200416161245.148813-1-samitolvanen@google.com> X-Mailer: git-send-email 2.26.1.301.g55bc3eb7cb9-goog Subject: [PATCH v11 07/12] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , James Morse , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Masahiro Yamada , Michal Marek , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Masami Hiramatsu , Nick Desaulniers , Jann Horn , Miguel Ojeda , 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) -- 2.26.1.301.g55bc3eb7cb9-goog