From patchwork Thu Jul 21 17:28:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12925653 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73F50CCA489 for ; Thu, 21 Jul 2022 17:28:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231274AbiGUR2R (ORCPT ); Thu, 21 Jul 2022 13:28:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229915AbiGUR2R (ORCPT ); Thu, 21 Jul 2022 13:28:17 -0400 Received: from mail-oa1-x36.google.com (mail-oa1-x36.google.com [IPv6:2001:4860:4864:20::36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7CB578AB07 for ; Thu, 21 Jul 2022 10:28:15 -0700 (PDT) Received: by mail-oa1-x36.google.com with SMTP id 586e51a60fabf-10c0119dd16so3299506fac.6 for ; Thu, 21 Jul 2022 10:28:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=N1mPfR3D12ZnGHuxmP4MWOfQkjon3IFNK8YMkGzC5zg=; b=AK+QQ07cWg5OzZYxkHTagjOQVVhcMylfq0iUug7TKRBMO4je+Hyjphi5L6Oy++ntVY hD9+BcYVn1+pGlKypGr+DIG6uKTSSql1iw69t9a3NqFVXnWh76Y9r9hik483VgrU6jmZ MZYXmLVlTbWBUZNPyPyvGksxg2e+ceQYEpPUU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=N1mPfR3D12ZnGHuxmP4MWOfQkjon3IFNK8YMkGzC5zg=; b=1tqHtiM9xuXF/B/VUoeiw1OAIgtQ1se5Bvb+BR9Kt4vs6mvIt5YDE84hGgDTzBnzd2 qkpqRq2KxcZ+wD41Q2ME3SPjW9/Ym1LPcK90RR87c0JEz9yLeOnRnY2kAV5kuJiqSFXC /Vx6SNv7UuEJOxJu0JAJ2Wvmps1DuBit189w9W/xPFBs/TuIzFqAu8WKl4U/tGdIFyBd cZbxIprHggoTxBmKaiUuQTeaqL5YAc4hKcbo11QUcveZX6OTkGwEajnHMOVGCTEDxu9n s7fJ+ctbZAfLCjEARs41Rdu8JOld4YYxyGYU8aeWpnl0EKd6XlJG87ztWLrw7cY3m99H QM/Q== X-Gm-Message-State: AJIora9bDyWb2dAYxDYX5q2qiQEkKvHaKwMzU1xaeknMIWEFyUBKUluS CJumuLZWwHmahNE8LFSH7uGGyA== X-Google-Smtp-Source: AGRyM1ucz1/qbrcJkssVY75ngCanvcCZN+R6AF84LUHfijoH0ifhCLQYVSwrkU4TK8tIsfKFLjjkdA== X-Received: by 2002:a05:6870:9a09:b0:e9:20a7:6cf6 with SMTP id fo9-20020a0568709a0900b000e920a76cf6mr5980435oab.122.1658424494733; Thu, 21 Jul 2022 10:28:14 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id du24-20020a0568703a1800b00101c83352c6sm1106207oab.34.2022.07.21.10.28.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jul 2022 10:28:14 -0700 (PDT) From: Frederick Lawler To: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com, paul@paul-moore.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com, ebiederm@xmission.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, cgzones@googlemail.com, karl@bigbadwolfsecurity.com, Frederick Lawler Subject: [PATCH v3 0/4] Introduce security_create_user_ns() Date: Thu, 21 Jul 2022 12:28:04 -0500 Message-Id: <20220721172808.585539-1-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org While creating a LSM BPF MAC policy to block user namespace creation, we used the LSM cred_prepare hook because that is the closest hook to prevent a call to create_user_ns(). The calls look something like this: cred = prepare_creds() security_prepare_creds() call_int_hook(cred_prepare, ... if (cred) create_user_ns(cred) We noticed that error codes were not propagated from this hook and introduced a patch [1] to propagate those errors. The discussion notes that security_prepare_creds() is not appropriate for MAC policies, and instead the hook is meant for LSM authors to prepare credentials for mutation. [2] Ultimately, we concluded that a better course of action is to introduce a new security hook for LSM authors. [3] This patch set first introduces a new security_create_user_ns() function and userns_create LSM hook, then marks the hook as sleepable in BPF. Links: 1. https://lore.kernel.org/all/20220608150942.776446-1-fred@cloudflare.com/ 2. https://lore.kernel.org/all/87y1xzyhub.fsf@email.froward.int.ebiederm.org/ 3. https://lore.kernel.org/all/9fe9cd9f-1ded-a179-8ded-5fde8960a586@cloudflare.com/ Past discussions: V2: https://lore.kernel.org/all/20220707223228.1940249-1-fred@cloudflare.com/ V1: https://lore.kernel.org/all/20220621233939.993579-1-fred@cloudflare.com/ Changes since v2: - Rename create_user_ns hook to userns_create - Use user_namespace as an object opposed to a generic namespace object - s/domB_t/domA_t in commit message Changes since v1: - Add selftests/bpf: Add tests verifying bpf lsm create_user_ns hook patch - Add selinux: Implement create_user_ns hook patch - Change function signature of security_create_user_ns() to only take struct cred - Move security_create_user_ns() call after id mapping check in create_user_ns() - Update documentation to reflect changes Frederick Lawler (4): security, lsm: Introduce security_create_user_ns() bpf-lsm: Make bpf_lsm_userns_create() sleepable selftests/bpf: Add tests verifying bpf lsm userns_create hook selinux: Implement userns_create hook include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 + include/linux/security.h | 6 ++ kernel/bpf/bpf_lsm.c | 1 + kernel/user_namespace.c | 5 ++ security/security.c | 5 ++ security/selinux/hooks.c | 9 ++ security/selinux/include/classmap.h | 2 + .../selftests/bpf/prog_tests/deny_namespace.c | 88 +++++++++++++++++++ .../selftests/bpf/progs/test_deny_namespace.c | 39 ++++++++ 10 files changed, 160 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/deny_namespace.c create mode 100644 tools/testing/selftests/bpf/progs/test_deny_namespace.c Nacked-by: "Eric W. Biederman" --- 2.30.2