From patchwork Fri Oct 18 16:10:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11199045 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 58EB217EE for ; Fri, 18 Oct 2019 16:13:30 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 23A5721D7C for ; Fri, 18 Oct 2019 16:13:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qgbEQaGz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23A5721D7C 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-17020-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 11593 invoked by uid 550); 18 Oct 2019 16:13:26 -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 9659 invoked from network); 18 Oct 2019 16:10:56 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=t+DRDqz67Twe6Iyofi8RQAeNodEvIc7fNPUNsIrBR+w=; b=qgbEQaGzHqaPH3cxTJE6CGTvZ+cRjHUHTkYr1B9DStapni7EFSvFnUDWSGPFTm7gwQ BQRlnzPOMPn4q93e238qrgFaMvCQf9Spzz7SINiIlVpuYks/Wu8Nwa1QmimiSJxpH3pA zXtHmrE7MTXaAB6BLpC8vL3pFXfn9A40pGj+qHFCNXTwD0ywpccoB55v3hYAWCkjkCgv t4a0qzeiaiVD3qeEEiRLETv6os7mi6JMjFcZQ7HZ3TsPYfuCCRN07OVVFEBv060hDwM0 Oe2+l3QRysVBZMWOYZ/v2Sou4QvuVNVoxWjAknk7l6ulOzhXQHgz5ej8/LwC2yX3JfcO auvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=t+DRDqz67Twe6Iyofi8RQAeNodEvIc7fNPUNsIrBR+w=; b=VomtYPZSOTLV15Liv9ZFD6bZTQBjj8/Tv+jklSSTS36kgTGsBUjAE60iNpZttiO7Ih 5zUjDZEHAtxeXJK2YvSX7i/6X+zkN15sJBeQu0I52eYK0KguSQraua2aWowoDvMLXtcF 0eya5dk9mVcPzCh+yJCXiNB6Oa8q6d5m+PUWdCB5zPS0U64YMiQAPLGv6QYigte+dvVI d25neW3tdXnZXvgqMQUOlR7BgstZ4j67iIhK9iK3tx7kCGU2bt4UH2S5l2pL/W8b97Lz KrTb0vurmZuFExPTB3yylEc9TivGfMXaUqCrezUjS4TVLBiYUgB95jzeqBjzcwhAcTp9 vc2Q== X-Gm-Message-State: APjAAAW7HbkzHs9t3Uk+T7u3+qZ8V6I1VRjqdeLNHAl8UpqKCX6K0W81 SpclbjoZXwY2J02Nckyeiuk+0DX/0ad6qARqR74= X-Google-Smtp-Source: APXvYqyvgW1/nPqoxtlaKdWfjDEG7KEXwdtGVI7DdMRD1tlwHR6z5N+W9oDyStEa7Ea2uqFWOqGCG100k3GuhoDibZE= X-Received: by 2002:a25:a324:: with SMTP id d33mr6752834ybi.58.1571415044349; Fri, 18 Oct 2019 09:10:44 -0700 (PDT) Date: Fri, 18 Oct 2019 09:10:15 -0700 Message-Id: <20191018161033.261971-1-samitolvanen@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.23.0.866.gb869b98d4c-goog Subject: [PATCH 00/18] add support for Clang's Shadow Call Stack From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen This patch series adds support for Clang's Shadow Call Stack (SCS) mitigation, which uses a separately allocated shadow stack to protect against return address overwrites. More information can be found here: https://clang.llvm.org/docs/ShadowCallStack.html SCS is currently supported only on arm64, where the compiler requires the x18 register to be reserved for holding the current task's shadow stack pointer. Because of this, the series includes four patches from Ard to remove x18 usage from assembly code and to reserve the register from general allocation. With -fsanitize=shadow-call-stack, the compiler injects instructions to all non-leaf C functions to store the return address to the shadow stack and unconditionally load it again before returning. As a result, SCS is incompatible with features that rely on modifying function return addresses to alter control flow, such as function graph tracing and kretprobes. A copy of the return address is still kept in the kernel stack for compatibility with stack unwinding, for example. SCS has a minimal performance overhead, but allocating shadow stacks increases kernel memory usage. The feature is therefore mostly useful on hardware that lacks support for PAC instructions. This series adds a ROP protection choice to the kernel configuration, where other return address protection options can be selected as they are added to the kernel. Ard Biesheuvel (4): arm64/lib: copy_page: avoid x18 register in assembler code arm64: kvm: stop treating register x18 as caller save arm64: kernel: avoid x18 as an arbitrary temp register arm64: kbuild: reserve reg x18 from general allocation by the compiler Sami Tolvanen (14): arm64: mm: don't use x18 in idmap_kpti_install_ng_mappings add support for Clang's Shadow Call Stack (SCS) scs: add accounting scs: add support for stack usage debugging trace: disable function graph tracing with SCS kprobes: fix compilation without CONFIG_KRETPROBES kprobes: disable kretprobes with SCS arm64: reserve x18 only with Shadow Call Stack arm64: preserve x18 when CPU is suspended arm64: efi: restore x18 if it was corrupted arm64: vdso: disable Shadow Call Stack arm64: kprobes: fix kprobes without CONFIG_KRETPROBES arm64: disable SCS for hypervisor code arm64: implement Shadow Call Stack Makefile | 6 + arch/Kconfig | 41 ++++- arch/arm64/Kconfig | 1 + arch/arm64/Makefile | 4 + arch/arm64/include/asm/scs.h | 60 ++++++++ arch/arm64/include/asm/stacktrace.h | 4 + arch/arm64/include/asm/thread_info.h | 3 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/asm-offsets.c | 3 + arch/arm64/kernel/cpu-reset.S | 4 +- arch/arm64/kernel/efi-rt-wrapper.S | 7 +- arch/arm64/kernel/entry.S | 23 +++ arch/arm64/kernel/head.S | 9 ++ arch/arm64/kernel/irq.c | 2 + arch/arm64/kernel/probes/kprobes.c | 2 + arch/arm64/kernel/process.c | 3 + arch/arm64/kernel/scs.c | 39 +++++ arch/arm64/kernel/smp.c | 4 + arch/arm64/kernel/vdso/Makefile | 2 +- arch/arm64/kvm/hyp/Makefile | 3 +- arch/arm64/kvm/hyp/entry.S | 12 +- arch/arm64/lib/copy_page.S | 38 ++--- arch/arm64/mm/proc.S | 69 +++++---- drivers/base/node.c | 6 + fs/proc/meminfo.c | 4 + include/linux/compiler-clang.h | 2 + include/linux/compiler_types.h | 4 + include/linux/mmzone.h | 3 + include/linux/scs.h | 88 +++++++++++ init/init_task.c | 6 + init/main.c | 3 + kernel/Makefile | 1 + kernel/fork.c | 9 ++ kernel/kprobes.c | 38 ++--- kernel/sched/core.c | 2 + kernel/sched/sched.h | 1 + kernel/scs.c | 221 +++++++++++++++++++++++++++ kernel/trace/Kconfig | 1 + mm/page_alloc.c | 6 + mm/vmstat.c | 3 + 40 files changed, 656 insertions(+), 82 deletions(-) create mode 100644 arch/arm64/include/asm/scs.h create mode 100644 arch/arm64/kernel/scs.c create mode 100644 include/linux/scs.h create mode 100644 kernel/scs.c Reviewed-by: Mark Rutland