From patchwork Wed Apr 1 21:39:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Colascione X-Patchwork-Id: 11469585 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 CC8AE1892 for ; Wed, 1 Apr 2020 21:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB40520772 for ; Wed, 1 Apr 2020 21:39:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HtoDxjxy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733035AbgDAVjN (ORCPT ); Wed, 1 Apr 2020 17:39:13 -0400 Received: from mail-pg1-f202.google.com ([209.85.215.202]:42567 "EHLO mail-pg1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732441AbgDAVjM (ORCPT ); Wed, 1 Apr 2020 17:39:12 -0400 Received: by mail-pg1-f202.google.com with SMTP id g10so1184486pgg.9 for ; Wed, 01 Apr 2020 14:39:12 -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=HAGgUYyHHln+iAOn6yXYvlgWPJe/4zWvRIw0PRHR3XY=; b=HtoDxjxyzs5b33ZeGM32Er5kRybPkg8YGOpir27RQ+bUpw6BX/dsJ2vwWdB3AAxCmG bjMfAIMdlb4UR1AIOIFCN+uc1kmAxsGNUeUv/O7Of7mXZUnwD7KGKYartbCqcARuZu5S pfkX1UGvumlx5lTd6PNZtdcgvvGSJ7bd4ydHOqBQDCYH8LMYmqHxRXGVp/ZzYI03Cvnf V4GJQtkEQ2I/BOGpkkbnC2McxJw07GBcQ5N+j9kMTmPQ3mXOmGip3EI4TVF0z+UmDcdV yHb87MmDuy1wgu53qGGYxbpjE5SRwjOxs4/Vz56t9Aqd6UVnoio9UyUMS51Lxck57Al/ 2iVg== 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=HAGgUYyHHln+iAOn6yXYvlgWPJe/4zWvRIw0PRHR3XY=; b=U0GZOCnW2Ksq8xGbUoP7NoTLsDR984U2QuQ+6sUYFyB5PcVfG8QZoUSLazkgHrh8jw prcYOKbk4oY8AYvV3KDZcUzK3ckEDrmojQlt/fIx12vwKQ5t1drQpluT8bidewhlQxFF PwnTyL5NV7gOevLS6C/WmAGCXYHA2O6tw8TE0Z08a+DDQBvdZ/roNH4UsF8BuhRO+pYv U1OL4Tgo8CQf3G/9e+NGO9cZwAhzKQN2z2lIdIPZnXsh13Ep202XvCQiAdKoc4ci75mU 6OdMdoEkrVGLKrLilBRZ2dJ87Hc5sUFo/Ufi0GUxdGhF3OGw0NTkGOz1OP+cksTJP/bn qXog== X-Gm-Message-State: AGi0Pub7TTMFBWk8SH0PC23eb0VRiqwhBwT/y/JPh9vDA4sDMx6WyxYT 1EtmMnnqpLUa5Vy6k43laZ4MOlPXx9s= X-Google-Smtp-Source: APiQypJ3mXXgEz84cKvOfB4JITXTTQgCH9bS0I77D6jC/rreVESODIDpq8LIxGqLwRsYwdoGgUvE2wVKYE8= X-Received: by 2002:a17:90b:3583:: with SMTP id mm3mr13268pjb.123.1585777151523; Wed, 01 Apr 2020 14:39:11 -0700 (PDT) Date: Wed, 1 Apr 2020 14:39:00 -0700 In-Reply-To: <20200326200634.222009-1-dancol@google.com> Message-Id: <20200401213903.182112-1-dancol@google.com> Mime-Version: 1.0 References: <20200326200634.222009-1-dancol@google.com> X-Mailer: git-send-email 2.26.0.rc2.310.g2932bb562d-goog Subject: [PATCH v5 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()) Changes from the fourth version of the patch: - Removed an unused parameter from an internal function - Fixed function documentation [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 | 191 ++++++++++++++++++++++------ 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, 267 insertions(+), 45 deletions(-) Acked-by: Stephen Smalley