From patchwork Fri Dec 9 16:04:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jeff Xu X-Patchwork-Id: 2827 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:f944:0:0:0:0:0 with SMTP id q4csp860629wrr; Fri, 9 Dec 2022 08:08:00 -0800 (PST) X-Google-Smtp-Source: AA0mqf5n0c3vcq9GXeVO3JPSKgwwmwtvULRl7Kx02q+5z1f/T/oL3Ew+THYAsMrKT1xiHdKBq/zt X-Received: by 2002:a17:902:a409:b0:185:441e:90de with SMTP id p9-20020a170902a40900b00185441e90demr6023543plq.68.1670602080329; Fri, 09 Dec 2022 08:08:00 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1670602080; cv=none; d=google.com; s=arc-20160816; b=znVoe2SybJ0v9uuFkTrNHuogiHRe5uS8tAg/r4XlKRCR6t55/1e3M1cocPsM1MXJzA 4yO7bOQfbcjugK3a61D2C+MaGvlclUtr9Q/Od7iwEuDSabdGcxrg2Riw3TcRlkHRWZBj stKPsPIcgcuf+0fx+orfxA+5b7GBwH6EotoNhlo9I+I2TC0JO10Tvni3XOtCYU5p61QZ BXteJzgPvKXkwWg/JUk+WwgPLrCdR6USxgc3Qz4jQBUezA1l4jIZsCASIXgfM3sR+dTm iSzzS3eDRQ8vKwWtSnTod9xgveA8gJqayyzUu9AXIf/tHfv6UqtbRxITHp5YatJA6gmD wnVw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=ueWjZxTYbaDQuWzBrDeCTZV53qbvnkwWshi5C3odIuU=; b=IHWLHdQkjis9qD0z5vtwnK4tNJQdRKUahInipDBhZX6+G8++mCOdMvOfPamIj4nGUm X4Hg8Wu/2i7VrELcbOUmamhWUnACVSTVDqgYsDSBjf1sK93zkszI7wyT5diCSX0WMtU6 /jC2hm2LdK8Zh6g8wPo/ZWnTSB2P7xfoUykZWKxY6Zj5knw+jV1JXYEJUvzxY1Gv/rfY R8GEwf4OuTEsHAWxbuhHI8QM+Gk6oGwemRUj5+0+BUivarRyf9RHzp1MZ6nlPL6LCcXB v6cXiDFpG/cF/TkkYtKbDuNhgJiUSu2iT7mamUDgF4Xq0C2VhG2ibxYIrqaisi/jdbnD iD+w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=EWSu99la; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id q18-20020a170902eb9200b001898144990dsi1849131plg.105.2022.12.09.08.07.47; Fri, 09 Dec 2022 08:08:00 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=EWSu99la; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230092AbiLIQFE (ORCPT + 99 others); Fri, 9 Dec 2022 11:05:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229604AbiLIQFB (ORCPT ); Fri, 9 Dec 2022 11:05:01 -0500 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60469511D8 for ; Fri, 9 Dec 2022 08:05:00 -0800 (PST) Received: by mail-pg1-x52c.google.com with SMTP id h193so3803227pgc.10 for ; Fri, 09 Dec 2022 08:05:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=ueWjZxTYbaDQuWzBrDeCTZV53qbvnkwWshi5C3odIuU=; b=EWSu99laS2GBJK/j/npVWxjB2fyUhNZIb5ap7uGNrpmhSjYdFN/R5KpVoxG7XCsT28 eSKCiuIsD3XZsUYjZbzlb6EMTTSOe2j5irk0ak1/VsWmw5GdGbvIraYAA7d8py5Y9LVc gc+Rh7B/MQTSKEPQllLXMnkWdzW6pKuiXnL2U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ueWjZxTYbaDQuWzBrDeCTZV53qbvnkwWshi5C3odIuU=; b=al65JkZ4r0cIMYLBf7eFJlQ+DnNS2p76Q2THIEvSRHhLZiHqI1wGuZ28IJC32nvv5W JvcxTJew0IJP9iy2ic5NDAEdtKWE81z2jRHS1zgxuGh1VljudtUBD+Ck5aJABBbdhv0f So/dAvByl0bTYFswzrfxAN5qiKnCUFBorBrZN0qJtM+9J5k56LCikiZtioH5fbba7E06 8LuX+I4njN1kyJfLF29VrPsAc15Kup+UDvPoQyHYZXYJHhrcgcCKoNZbV4DKyMYbjSNJ Vq1THUe08a9q1kFFTQQrTfiOg0MiaRuVNPAPDw8aSYV/M84UjdQLlhqlvysXP8+yG8i0 2b5g== X-Gm-Message-State: ANoB5pmpYi/bGTNc+Idb+Z3GhWIvKbrG3qEKOhDQi27YQjWFnTGDsrRv C4Q1KTKRlrAeH7zRb3wxCgTGnA== X-Received: by 2002:a62:87cc:0:b0:576:dc40:6db9 with SMTP id i195-20020a6287cc000000b00576dc406db9mr6237516pfe.13.1670601899690; Fri, 09 Dec 2022 08:04:59 -0800 (PST) Received: from jeffxud.c.googlers.com.com (30.202.168.34.bc.googleusercontent.com. [34.168.202.30]) by smtp.gmail.com with ESMTPSA id a15-20020aa795af000000b00576670cc170sm1460504pfk.93.2022.12.09.08.04.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Dec 2022 08:04:59 -0800 (PST) From: jeffxu@chromium.org To: skhan@linuxfoundation.org, keescook@chromium.org Cc: akpm@linux-foundation.org, dmitry.torokhov@gmail.com, dverkamp@chromium.org, hughd@google.com, jeffxu@google.com, jorgelo@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, jannh@google.com, linux-hardening@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v7 0/6] mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC Date: Fri, 9 Dec 2022 16:04:47 +0000 Message-Id: <20221209160453.3246150-1-jeffxu@google.com> X-Mailer: git-send-email 2.39.0.rc1.256.g54fd8350bd-goog MIME-Version: 1.0 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751753246941186251?= X-GMAIL-MSGID: =?utf-8?q?1751753246941186251?= From: Jeff Xu Since Linux introduced the memfd feature, memfd have always had their execute bit set, and the memfd_create() syscall doesn't allow setting it differently. However, in a secure by default system, such as ChromeOS, (where all executables should come from the rootfs, which is protected by Verified boot), this executable nature of memfd opens a door for NoExec bypass and enables “confused deputy attack”. E.g, in VRP bug [1]: cros_vm process created a memfd to share the content with an external process, however the memfd is overwritten and used for executing arbitrary code and root escalation. [2] lists more VRP in this kind. On the other hand, executable memfd has its legit use, runc uses memfd’s seal and executable feature to copy the contents of the binary then execute them, for such system, we need a solution to differentiate runc's use of executable memfds and an attacker's [3]. To address those above, this set of patches add following: 1> Let memfd_create() set X bit at creation time. 2> Let memfd to be sealed for modifying X bit. 3> A new pid namespace sysctl: vm.memfd_noexec to control the behavior of X bit.For example, if a container has vm.memfd_noexec=2, then memfd_create() without MFD_NOEXEC_SEAL will be rejected. 4> A new security hook in memfd_create(). This make it possible to a new LSM, which rejects or allows executable memfd based on its security policy. Change history: v7: - patch 2/6: remove #ifdef and MAX_PATH (memfd_test.c). - patch 3/6: check capability (CAP_SYS_ADMIN) from userns instead of global ns (pid_sysctl.h). Add a tab (pid_namespace.h). - patch 5/6: remove #ifdef (memfd_test.c) - patch 6/6: remove unneeded security_move_mount(security.c). v6:https://lore.kernel.org/lkml/20221206150233.1963717-1-jeffxu@google.com/ - Address comment and move "#ifdef CONFIG_" from .c file to pid_sysctl.h v5:https://lore.kernel.org/lkml/20221206152358.1966099-1-jeffxu@google.com/ - Pass vm.memfd_noexec from current ns to child ns. - Fix build issue detected by kernel test robot. - Add missing security.c v3:https://lore.kernel.org/lkml/20221202013404.163143-1-jeffxu@google.com/ - Address API design comments in v2. - Let memfd_create() to set X bit at creation time. - A new pid namespace sysctl: vm.memfd_noexec to control behavior of X bit. - A new security hook in memfd_create(). v2:https://lore.kernel.org/lkml/20220805222126.142525-1-jeffxu@google.com/ - address comments in V1. - add sysctl (vm.mfd_noexec) to set the default file permissions of memfd_create to be non-executable. v1:https://lwn.net/Articles/890096/ [1] https://crbug.com/1305411 [2] https://bugs.chromium.org/p/chromium/issues/list?q=type%3Dbug-security%20memfd%20escalation&can=1 [3] https://lwn.net/Articles/781013/ Daniel Verkamp (2): mm/memfd: add F_SEAL_EXEC selftests/memfd: add tests for F_SEAL_EXEC Jeff Xu (4): mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC mm/memfd: Add write seals when apply SEAL_EXEC to executable memfd selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC mm/memfd: security hook for memfd_create include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 + include/linux/pid_namespace.h | 19 ++ include/linux/security.h | 6 + include/uapi/linux/fcntl.h | 1 + include/uapi/linux/memfd.h | 4 + kernel/pid_namespace.c | 5 + kernel/pid_sysctl.h | 59 ++++ mm/memfd.c | 61 +++- mm/shmem.c | 6 + security/security.c | 5 + tools/testing/selftests/memfd/fuse_test.c | 1 + tools/testing/selftests/memfd/memfd_test.c | 341 ++++++++++++++++++++- 13 files changed, 510 insertions(+), 3 deletions(-) create mode 100644 kernel/pid_sysctl.h base-commit: eb7081409f94a9a8608593d0fb63a1aa3d6f95d8