From patchwork Tue Mar 9 21:42:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 12126635 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=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 F29C0C433DB for ; Tue, 9 Mar 2021 21:44:19 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 40BAC64FC4 for ; Tue, 9 Mar 2021 21:44:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40BAC64FC4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-20895-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 15953 invoked by uid 550); 9 Mar 2021 21:43:27 -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: Received: (qmail 15695 invoked from network); 9 Mar 2021 21:43:24 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Ir1++GyLBl5f/Xqi2kq3Ks3S4B0/Ta3jdChtS1vi2CQ=; b=PQpY2pYxmPsNBXFkbbyfqSO75eYKbfp34/QOywDWc25NjIe3QuTej3PxF3gjC7fxze b8opA6Cs0pOw/2dA2QtI0IzU+nm/QM09KbOo00JckZNnZste6/TcuqqsPb8jccMu1wnJ hD7dA1q1g2DBqkhqSXzb6rBpP319jcb+bS9hk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Ir1++GyLBl5f/Xqi2kq3Ks3S4B0/Ta3jdChtS1vi2CQ=; b=tzr81UWXjuZZRuNmIp3+wo4LkS7+NsTGvWPnXaQJmw9YwAT5yFBqB+Pk5vwe4omy0+ GN44AZUxbEl4dSHe1BYZ0S19GaSBiuA171xifDCJJY9+cCdVcaBdBKLKUxRO7hhjDxqN s0eEReeSMct0rQJD/Ry1ytq+ZcrXWneP29e1JhNPQM1cIp9o7p0nNzPJMszRF0ewnheG oGukHzZDlExpEz2xAASUEvwCvUXk3A685ISQW7tCb7HaYIdH5ank7bCgtVJBaNN0kBPp 2ZfZDRpX2vnwWSUjUUyTyg2brpVKGpYBHXGeqNMUj9Foy7/SCdSjxHn1vgIcJqI+0/sz AJdQ== X-Gm-Message-State: AOAM5326+MkQIJEFnfmAiCT06/jfTycqnLhfmdLM8wjg7VRwGYPmL+Ka 5C7TpSEH+9YgY2VCQkUwVBGORg== X-Google-Smtp-Source: ABdhPJwPbX2CP08JIvGDKPgOsOudkdGoKPD7zbVHSsyKSWs27JHzaot43YDrMLue1TNE7gbMQ141PA== X-Received: by 2002:a17:90a:cb12:: with SMTP id z18mr6430185pjt.132.1615326191909; Tue, 09 Mar 2021 13:43:11 -0800 (PST) From: Kees Cook To: Thomas Gleixner Cc: Kees Cook , Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Alexander Popov , Ard Biesheuvel , Jann Horn , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , David Hildenbrand , Mike Rapoport , Andrew Morton , Jonathan Corbet , Randy Dunlap Subject: [PATCH v5 0/7] Optionally randomize kernel stack offset each syscall Date: Tue, 9 Mar 2021 13:42:54 -0800 Message-Id: <20210309214301.678739-1-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 v5: - rebase to v5.12-rc2 - clean up static branch issues introduced since v4 series - adjust comments (Mark Rutland) - update kernel-parameters.txt (Randy Dunlap) v4: https://lore.kernel.org/lkml/20200622193146.2985288-1-keescook@chromium.org/ v3: https://lore.kernel.org/lkml/20200406231606.37619-1-keescook@chromium.org/ v2: https://lore.kernel.org/lkml/20200324203231.64324-1-keescook@chromium.org/ rfc: https://lore.kernel.org/kernel-hardening/20190329081358.30497-1-elena.reshetova@intel.com/ Hi, This is a continuation and refactoring of Elena's earlier effort to add kernel stack base offset randomization. In the time since the earlier discussions, two attacks[1][2] were made public that depended on stack determinism, so we're no longer in the position of "this is a good idea but we have no examples of attacks". :) Earlier discussions also devolved into debates on entropy sources, which is mostly a red herring, given the already low entropy available due to stack size. Regardless, entropy can be changed/improved separately from this series as needed. Earlier discussions also got stuck debating how much syscall overhead was too much, but this is also a red herring since the feature itself needs to be selectable at boot with no cost for those that don't want it: this is solved here with static branches. So, here is the latest improved version, made as arch-agnostic as possible, with usage added for x86 and arm64. It also includes some small static branch clean ups, and addresses some surprise performance issues due to the stack canary[3]. At the very least, the first three patches should land ASAP, the first is a minor bug fix for v5.11. The next two are optimizations for static branch usage that Peter already Acked. If I can get an Ack from an arm64 maintainer, I think this could all land via -tip to make merging easiest. Thanks! -Kees [1] https://a13xp0p0v.github.io/2020/02/15/CVE-2019-18683.html [2] https://repositorio-aberto.up.pt/bitstream/10216/125357/2/374717.pdf [3] https://lore.kernel.org/lkml/202003281520.A9BFF461@keescook/ Kees Cook (7): mm: Restore init_on_* static branch defaults jump_label: Provide CONFIG-driven build state defaults init_on_alloc: Unpessimize default-on builds stack: Optionally randomize kernel stack offset each syscall x86/entry: Enable random_kstack_offset support arm64: entry: Enable random_kstack_offset support lkdtm: Add REPORT_STACK for checking stack offsets .../admin-guide/kernel-parameters.txt | 11 +++++ Makefile | 4 ++ arch/Kconfig | 23 ++++++++++ arch/arm64/Kconfig | 1 + arch/arm64/kernel/Makefile | 5 +++ arch/arm64/kernel/syscall.c | 10 +++++ arch/x86/Kconfig | 1 + arch/x86/entry/common.c | 3 ++ arch/x86/include/asm/entry-common.h | 8 ++++ drivers/misc/lkdtm/bugs.c | 17 ++++++++ drivers/misc/lkdtm/core.c | 1 + drivers/misc/lkdtm/lkdtm.h | 1 + include/linux/jump_label.h | 19 +++++++++ include/linux/mm.h | 10 +++-- include/linux/randomize_kstack.h | 42 +++++++++++++++++++ init/main.c | 23 ++++++++++ mm/page_alloc.c | 4 +- 17 files changed, 177 insertions(+), 6 deletions(-) create mode 100644 include/linux/randomize_kstack.h