From patchwork Thu Feb 4 17:47:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12068097 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=-16.1 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,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 22C57C433E0 for ; Thu, 4 Feb 2021 17:49:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD0A464E4E for ; Thu, 4 Feb 2021 17:49:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237699AbhBDRtk (ORCPT ); Thu, 4 Feb 2021 12:49:40 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:41768 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238756AbhBDRtG (ORCPT ); Thu, 4 Feb 2021 12:49:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612460859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=WoCQGzrOsnk55IaG+1UEwkLjcE8h9OKWofQDyL0qDdM=; b=WNcds/5J8A2CRnfAbZp51mb8VPvU3obyD1e+aAqeo/+WtUI4wFYirG3PAXank6pPoyOyr2 HLnpqn0HhRXDjaw5JtdZHWUY3x4bupPuUAl5JtnUoYBY/yI2ysbrKyvpdC8c/Fl8Ru4LTb pisRBeROEcV5IxCnqt1bSq+WZ4yE5po= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-195-lEo22RTJPJKzB2hJMUlSNw-1; Thu, 04 Feb 2021 12:47:36 -0500 X-MC-Unique: lEo22RTJPJKzB2hJMUlSNw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6D5A8107ACE3; Thu, 4 Feb 2021 17:47:34 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-115-23.rdu2.redhat.com [10.10.115.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 81C4062679; Thu, 4 Feb 2021 17:47:32 +0000 (UTC) Subject: [RFC][PATCH 0/2] keys: request_key() interception in containers From: David Howells To: sprabhu@redhat.com Cc: dhowells@redhat.com, Jarkko Sakkinen , christian@brauner.io, selinux@vger.kernel.org, keyrings@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org Date: Thu, 04 Feb 2021 17:47:31 +0000 Message-ID: <161246085160.1990927.13137391845549674518.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Here's a rough draft of a facility by which keys can be intercepted. There are two patches: (1) Add tags to namespaces that can be used to find out, when we're looking for an intercept, if a namespace that an intercept is filtering on is the same as namespace of the caller of request_key() without the need for the intercept record to pin the namespaces that it's using as filters (which would also cause a dependency cycle). Tags contain only a refcount and are compared by address. (2) Add a new keyctl: keyctl(KEYCTL_SERVICE_INTERCEPT, int queue_keyring, int userns_fd, const char *type_name, unsigned int ns_mask); that allows a request_key() intercept to be added to the specified user namespace. The authorisation key for an intercepted request is placed in the queue_keyring, which can be watched to gain a notification of this happening. The watcher can then examine the auth key to determine what key is to be instantiated. A simple sample is provided that can be used to try this. Some things that need to be worked out: (*) Intercepts are linked to the lifetime of the user_namespace on which they're placed, but not the daemon or the queue keyring. Probably they should be removed when the queue keyring is removed, but they currently pin it. (*) Setting userns_fd to other than -1 is not yet supported (-1 indicates the current user namespace). (*) Multiple threads can monitor a queue keyring, but they will all get woken. They can use keyctl_move() to decide who gets to process it. The patches can be found on the following branch: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=keys-intercept David --- David Howells (2): Add namespace tags that can be used for matching without pinning a ns keys: Allow request_key upcalls from a container to be intercepted include/linux/key-type.h | 4 +- include/linux/user_namespace.h | 2 + include/uapi/linux/keyctl.h | 13 + kernel/user.c | 3 + kernel/user_namespace.c | 2 + samples/watch_queue/Makefile | 2 + samples/watch_queue/key_req_intercept.c | 271 +++++++++++++++++++ security/keys/Makefile | 2 + security/keys/compat.c | 3 + security/keys/internal.h | 5 + security/keys/keyctl.c | 6 + security/keys/keyring.c | 1 + security/keys/process_keys.c | 2 +- security/keys/request_key.c | 16 +- security/keys/request_key_auth.c | 3 + security/keys/service.c | 337 ++++++++++++++++++++++++ 16 files changed, 663 insertions(+), 9 deletions(-) create mode 100644 samples/watch_queue/key_req_intercept.c create mode 100644 security/keys/service.c