From patchwork Mon Mar 15 18:02:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 12140319 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=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 7097EC433DB for ; Mon, 15 Mar 2021 18:03:09 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 880E164E81 for ; Mon, 15 Mar 2021 18:03:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 880E164E81 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-20936-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 11330 invoked by uid 550); 15 Mar 2021 18:02:50 -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 10218 invoked from network); 15 Mar 2021 18:02:48 -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=D9ES74tRjQPkQDGloZkJ7JzGqh/Rg5vOjLPTTzfWrnU=; b=nkyWI5GSq3VOZgbrSe5HgKjUqcwdRVsFgjMiU8cCOXgYni5mOUx2JpvpUeGfEIzjVc /EApzc0zoetCk9N/rKUGLhHwqdDHx/41U8LrjrtmFadM02lCoJ/nZFJdX85vtFgWgnHI h+0okdA6lvkzr6gdZBtYETfjATYKmdov+9h6Q= 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=D9ES74tRjQPkQDGloZkJ7JzGqh/Rg5vOjLPTTzfWrnU=; b=erpNTxZLiDc8zqBLXhp+OZ7nHPL/AtewK/E8VUe0w/V1Lpxdk+JrxqzIJph3aGlU+K L1Llz5gFKFV1m5KKh8KPP4P8OOdQzGvIxe0zD81NPzaDtEKhEdmEgLT5do6j6CrIJx9X pVMeX7MnxNuGeUX/QKZglfIfe6P98UWqjEIFsLg0H4HPnt7B4xW4pmXYuw4bdmiqDeNI 3hsL2efODHGXDPn3FGR3n5NWVuBWHcHGKnmP3WnZh68aXgzNmS0oma8NgprtckjlBeo9 6CewzTywjcCLB9YAwDrj6gtsBgr8FpsIxHAnInp8rmdMJps8BZlNWsfp9AAaJR9lyxDt ysOw== X-Gm-Message-State: AOAM532XZOf+j8l1AG8J+KmacTEkkM7zmmHRBHQdnR/qBpKx3ZnYRaEd zFYyortKJKsVHMdgTJuJYm6aSw== X-Google-Smtp-Source: ABdhPJwdcjtS5Z2P+DmTf0KAvanjziv2viUkjFPb2OQot1M+A70P++yEN5oAbiQpcrSGAjwehcCvpA== X-Received: by 2002:a17:90a:2c09:: with SMTP id m9mr300524pjd.3.1615831356695; Mon, 15 Mar 2021 11:02:36 -0700 (PDT) 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 , Vlastimil Babka , David Hildenbrand , Mike Rapoport , Andrew Morton , Jonathan Corbet , Randy Dunlap , 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 Subject: [PATCH v6 0/6] Optionally randomize kernel stack offset each syscall Date: Mon, 15 Mar 2021 11:02:23 -0700 Message-Id: <20210315180229.1224655-1-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 v6: - rearrange jump_label and init_on_* changes (akpm) - add slab init_on_* static branches (andreyknvl) v5: https://lore.kernel.org/lkml/20210309214301.678739-1-keescook@chromium.org/ 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 two patches can land separately (already Acked and Reviewed), since they're kind of "separate", but introduce macros that are used in the core stack changes. 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 (6): jump_label: Provide CONFIG-driven build state defaults init_on_alloc: Optimize static branches 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 +- mm/slab.h | 6 ++- 18 files changed, 181 insertions(+), 8 deletions(-) create mode 100644 include/linux/randomize_kstack.h