From patchwork Thu Oct 24 22:51:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11211861 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CBD80139A for ; Fri, 25 Oct 2019 09:29:12 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 2A95320867 for ; Fri, 25 Oct 2019 09:29:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uLf+lw77" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2A95320867 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17118-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 7701 invoked by uid 550); 25 Oct 2019 09:28:08 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 19779 invoked from network); 24 Oct 2019 22:52:38 -0000 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=+uiLq+iUoKYbKnLFQDjwDIIzqGudQy8o1UFEOkmkrHU=; b=uLf+lw77gVEoxfyZjVffG8N9AkGSFT6SZ7rKTY6igTbvtmj5tkgs6S87yKXapR9kBD NfJzX9FsM1QPF/BRZh7tuTNd9Bft+wBmoGpSgAiFGgU/eFojwHMx3hY/jiQo5OXG88H+ n+2/sETYJSjx1UwcF1JDwNNf9o+ndIsqNQGNcfRmpV1CBEoxTmXgI879l/WxjZMkcbmb kFXbiNvmWzULL9yr6G9yxYiRMJuYM6XDRrKUuDcJ0X91UFc9CGS/3Wg/GkwQsbD/KzdG KcYEc9VsXZBk/vRUd/5xFUU2jMu6PAXVjvl8vJIQVZYzQ1oFFfyD8naEYVJQbR65Robs mdBA== 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=+uiLq+iUoKYbKnLFQDjwDIIzqGudQy8o1UFEOkmkrHU=; b=nVJBpniI/KDSjO05IWZYPZQ4mwl+n2w0QBk330vK8b+gQ0UL0qQ+aPeLaxMqEMnZ0e EWYlDuVeQ2d467QrZklEsy/LX+ugY6CcdQNpvj/bLJt2ITmZeKlIcYYyep6Uoz53pIKp e8wdhRTDNuSxZt1/zhzJY1y85WbR9tfC6r1hHhkY8mDjuLhEaUffa9p4yYg4W31TPIdo K1kEGqA+uQJtK6tdC/eikkwTQ5Y9uJduPciAZca6yzRazWbKOE7og7Nh53F8noXsQH5D 8ZYet38iLrdpXi1XIS0zrDnKV/Hz+Kq7TR8WWrFVnE7qB3je0tt5pKyYpnYsSZI4xGuF YwQw== X-Gm-Message-State: APjAAAVNephd0bO+6MiCH6e78wdYyNjkp76sVdPfK2YtyuGgeKHDRyF8 pbaATjZTtz2ck+HkCQyRoxm4ZoC3Wv1bLEKgm5U= X-Google-Smtp-Source: APXvYqzRSdeSSRgGBGnoZCPWuY69NwMrQK4NIj2mmmt3agCQs8uemlrog/B126rrh1wmew1IPRee+I1rJJkV4cdOR3k= X-Received: by 2002:a9f:2271:: with SMTP id 104mr36427uad.127.1571957546730; Thu, 24 Oct 2019 15:52:26 -0700 (PDT) Date: Thu, 24 Oct 2019 15:51:28 -0700 In-Reply-To: <20191024225132.13410-1-samitolvanen@google.com> Message-Id: <20191024225132.13410-14-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191024225132.13410-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 13/17] arm64: efi: restore x18 if it was corrupted From: samitolvanen@google.com To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel Cc: Dave Martin , Kees Cook , 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, Sami Tolvanen 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 --- 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)