From patchwork Fri Dec 6 22:13:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11277087 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 9E08D14BD for ; Fri, 6 Dec 2019 22:15:52 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 0672D206DB for ; Fri, 6 Dec 2019 22:15:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="c1Wx0pmg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0672D206DB 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-17483-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 22215 invoked by uid 550); 6 Dec 2019 22:14:36 -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 Received: (qmail 22122 invoked from network); 6 Dec 2019 22:14:36 -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=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=RX7lHrhghduTDpLUyB0ZK43Fg0nyna1Al3sMTBxT9SGGA4GWxxTCDMolWK4BaOJeeT i0uHoj5QiC12kJeVcEWevT6W/0ViVOKSdZl6HRQKvyhgIRXKn7eFhiHMu0PYy3lZU0yk YNY5xLNzx/IvK1tMgcZGJMD/LpsL3lBakthc2QkCHifKfzGh9VRjIR794w+kmQIV1lp/ wUfdFZwhMsDJaDErUIj2Orz6KJ1dDBkT5DCHoaFxQnrQnp6nas5QbRR1I+EPSDb3eUCL +HXVp0MElzNgL5cAThHvXJqM+W9opB5xbENiy9eEwrbX6FdNi1+UygX6ifFcFfxnNpj9 Xt2g== X-Gm-Message-State: APjAAAU0ow8IsbrWdaTkcGMiqdJ5A2Rh1Jq8W1dDGBJ8dtulsJ5gLIep nbkLOe30VPfiECG3fTFtr1EAFyrXqMaaQ8gnSck= 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 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)