From patchwork Thu Mar 26 20:06:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Colascione X-Patchwork-Id: 11460981 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 51FD318E8 for ; Thu, 26 Mar 2020 20:06:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A3DD206E6 for ; Thu, 26 Mar 2020 20:06:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oQg2HiJA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728587AbgCZUGp (ORCPT ); Thu, 26 Mar 2020 16:06:45 -0400 Received: from mail-pg1-f201.google.com ([209.85.215.201]:52059 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726540AbgCZUGp (ORCPT ); Thu, 26 Mar 2020 16:06:45 -0400 Received: by mail-pg1-f201.google.com with SMTP id p13so5796739pgk.18 for ; Thu, 26 Mar 2020 13:06:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=WqHax6ECl9wbInrMxjIjOM9cZAwTrPkoL2M2jFKPBQE=; b=oQg2HiJAJN0uq3CanDGzoJhuUjBYjvhnGM82wp7T8u1ZLdJc0emxPSWGDOVo2hwXyD oYhF+R4VmJyHhW9agDvAQwLEQehvPDqs2xMeloGW6iyyNl7BkF+BMNrw6sO8n5tEHSRW Bj9P4BPDq3/5vV7bdFky1PCeCR2OwIF62INk4/iglpEogfPbio/6/tuFzLNw2BTLZnIM szYZf1bycO6HgHYsEnY0Fz1gYItaYnVEORPALjWBYguN7JqK9Z7cKiRowmRewMd8xCuQ 6QR0/l8leAZRocfTh5jgbffUm6anAdrZ0D82jPJYwvqKEtPgt/HsDIA4PDCLHV2pVl9e 5qwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=WqHax6ECl9wbInrMxjIjOM9cZAwTrPkoL2M2jFKPBQE=; b=oorEsxeyZQzqzquT5Pequiy/gmevvdxzHVCigdXeBYDejsTMOp5d63g/cBvcDnrLum syvohg05KvlFiGm4g2RAhIcriBIS7AKyh24fjYzCzKmDIZ2ag+CVSufsyMN3284EG+U9 TmvjHrexmwZlzYeyXFZZPedGH6yDY3F5GxPPlgogwSehOYwLYIOdHKPstiJMG4+k86ql i3MF+NnijffZAmgezWc4ULqxHMmVSwkGeLYst0agcb9552iq4IEVdl0PFMI9pruOgOPk l7KTCCHYM7Dm0Z8fhZU7wju9h00Or9A/2QtJIhJWCz/MDvPKflmDd1VtHn463P+WK0Gz hCGw== X-Gm-Message-State: ANhLgQ0c9yHvBlnJCXmwAkO7V+taOOxVrTXYxKK6uGUnmFjbaJy3Vvse +0BxDLPb7gK/j3CnA8Y5TgQaS7Y7mVQ= X-Google-Smtp-Source: ADFU+vvsk68FMQSxurQFf3aAeMUtjRxGtYQGqNwjBsk1ShThaxSUYG2MrLAemrcldb5fjvyCliNa2Z6slbk= X-Received: by 2002:a17:90a:e289:: with SMTP id d9mr1801523pjz.172.1585253203623; Thu, 26 Mar 2020 13:06:43 -0700 (PDT) Date: Thu, 26 Mar 2020 13:06:31 -0700 In-Reply-To: <20200326181456.132742-1-dancol@google.com> Message-Id: <20200326200634.222009-1-dancol@google.com> Mime-Version: 1.0 References: <20200326181456.132742-1-dancol@google.com> X-Mailer: git-send-email 2.25.1.696.g5e7596f4ac-goog Subject: [PATCH v4 0/3] SELinux support for anonymous inodes and UFFD From: Daniel Colascione To: timmurray@google.com, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, viro@zeniv.linux.org.uk, paul@paul-moore.com, nnk@google.com, sds@tycho.nsa.gov, lokeshgidra@google.com, jmorris@namei.org Cc: Daniel Colascione Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Userfaultfd in unprivileged contexts could be potentially very useful. We'd like to harden userfaultfd to make such unprivileged use less risky. This patch series allows SELinux to manage userfaultfd file descriptors and in the future, other kinds of anonymous-inode-based file descriptor. SELinux policy authors can apply policy types to anonymous inodes by providing name-based transition rules keyed off the anonymous inode internal name ( "[userfaultfd]" in the case of userfaultfd(2) file descriptors) and applying policy to the new SIDs thus produced. Inside the kernel, a pair of new anon_inodes interface, anon_inode_getfile_secure and anon_inode_getfd_secure, allow callers to opt into this SELinux management. In this new "secure" mode, anon_inodes creates new ephemeral inodes for anonymous file objects instead of reusing the normal anon_inodes singleton dummy inode. A new LSM hook gives security modules an opportunity to configure and veto these ephemeral inodes. This patch series is one of two fork of [1] and is an alternative to [2]. The primary difference between the two patch series is that this partch series creates a unique inode for each "secure" anonymous inode, while the other patch series ([2]) continues using the singleton dummy anonymous inode and adds a way to attach SELinux security information directly to file objects. I prefer the approach in this patch series because 1) it's a smaller patch than [2], and 2) it produces a more regular security architecture: in this patch series, secure anonymous inodes aren't S_PRIVATE and they maintain the SELinux property that the label for a file is in its inode. We do need an additional inode per anonymous file, but per-struct-file inode creation doesn't seem to be a problem for pipes and sockets. The previous version of this feature ([1]) created a new SELinux security class for userfaultfd file descriptors. This version adopts the generic transition-based approach of [2]. This patch series also differs from [2] in that it doesn't affect all anonymous inodes right away --- instead requiring anon_inodes callers to opt in --- but this difference isn't one of basic approach. The important question to resolve is whether we should be creating new inodes or enhancing per-file data. Changes from the first version of the patch: - Removed some error checks - Defined a new anon_inode SELinux class to resolve the ambiguity in [3] - Inherit sclass as well as descriptor from context inode Changes from the second version of the patch: - Fixed example policy in the commit message to reflect the use of the new anon_inode class. Changes from the third version of the patch: - Dropped the fops parameter to the LSM hook - Documented hook parameters - Fixed incorrect class used for SELinux transition - Removed stray UFFD changed early in the series - Removed a redundant ERR_PTR(PTR_ERR()) [1] https://lore.kernel.org/lkml/20200211225547.235083-1-dancol@google.com/ [2] https://lore.kernel.org/linux-fsdevel/20200213194157.5877-1-sds@tycho.nsa.gov/ [3] https://lore.kernel.org/lkml/23f725ca-5b5a-5938-fcc8-5bbbfc9ba9bc@tycho.nsa.gov/ Daniel Colascione (3): Add a new LSM-supporting anonymous inode interface Teach SELinux about anonymous inodes Wire UFFD up to SELinux fs/anon_inodes.c | 196 ++++++++++++++++++++++------ fs/userfaultfd.c | 30 ++++- include/linux/anon_inodes.h | 13 ++ include/linux/lsm_hooks.h | 11 ++ include/linux/security.h | 3 + security/security.c | 9 ++ security/selinux/hooks.c | 53 ++++++++ security/selinux/include/classmap.h | 2 + 8 files changed, 271 insertions(+), 46 deletions(-)