From patchwork Wed Aug 11 20:49:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Moore X-Patchwork-Id: 12431941 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=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9ADB5C432BE for ; Wed, 11 Aug 2021 20:49:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A8D76104F for ; Wed, 11 Aug 2021 20:49:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232149AbhHKUtz (ORCPT ); Wed, 11 Aug 2021 16:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232192AbhHKUti (ORCPT ); Wed, 11 Aug 2021 16:49:38 -0400 Received: from mail-qt1-x831.google.com (mail-qt1-x831.google.com [IPv6:2607:f8b0:4864:20::831]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1AFFC0617BA for ; Wed, 11 Aug 2021 13:49:03 -0700 (PDT) Received: by mail-qt1-x831.google.com with SMTP id y9so3208508qtv.7 for ; Wed, 11 Aug 2021 13:49:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore-com.20150623.gappssmtp.com; s=20150623; h=subject:from:to:date:message-id:in-reply-to:references:user-agent :mime-version:content-transfer-encoding; bh=aKsKoHqmsZAVF8Rg44lH5t0OfNGgPIxtypJyrDcBmw4=; b=IGSbf/s0ur37Nk3NPxnIck3BCoLugpdPaVsVyr30fmwA9kQWgXlHN0/W9s61/HjV32 ap/AcGfdjK7GODb5rGY+xW592XMZYImEigmWW9YalL9/PXLDBZPtGVB7p98MTG32luHp 2mCK8gO/ftHVYSiWS8ODZ4MTITXZ7D0S7KhgGqIaqRB6Kqg1U0dvKzHCmh4fap+uBoFO V4VOpBcQ6hzX7/gkU0pR8yAHU0LMzfR/zyhOXZf7wbWke9xZV3ZiGQaaDcWL0/YaPcnn myXuptVBKJeIAPRKJXIafRTsSQff8BZoPDFD27MINouLCa4HwPazChfBGjBAdPEjYRE3 83Rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=aKsKoHqmsZAVF8Rg44lH5t0OfNGgPIxtypJyrDcBmw4=; b=PZjM83wRrJ+ZaWmREmlUOUlrSqPq9UVCahUsm70i8ZnJQMIRLYZtCReayhQWq317Yk zDglCg5wHY2VBtZnx6608m0C9yrc+HoKUy/oMYyjsv4SYbOqzevFhfF8NNkKoum3xfKU F0Woc4EL271qTp7MrE3rryohbE69MBBrRGx/UZdKSZnGBlRC5gPC9vUq2D1jM5Di9L7o VfAjpceyMzKh2gyjY0XR//nmzAKeD9dWa0h2Df/3cfqCJAMZ+iVHNY9LkFoXmSB6s0Hn GamQhDodb//NIVQo1OZ/pZ6jk18YcNhTgGF8SCrGIAPq/Hsjj2hZsZsReZ93Q34tE7So bfpw== X-Gm-Message-State: AOAM5315HHrJ7fjSa+I12jirf1XfhIZoRQ3DAU+jtJELqNW91nvhUnnG w6wb22sHMBC4fBS+YP0JCN9X X-Google-Smtp-Source: ABdhPJwUNiEpaP+PnCDNAxzfQreTvk0/bSRZpum/ItWkECnR696IHTh5PszjLPJX8QmS68QTFRGQhw== X-Received: by 2002:ac8:4e33:: with SMTP id d19mr579232qtw.197.1628714942836; Wed, 11 Aug 2021 13:49:02 -0700 (PDT) Received: from localhost (pool-96-237-52-188.bstnma.fios.verizon.net. [96.237.52.188]) by smtp.gmail.com with ESMTPSA id h10sm181971qta.74.2021.08.11.13.49.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Aug 2021 13:49:02 -0700 (PDT) Subject: [RFC PATCH v2 8/9] selinux: add support for the io_uring access controls From: Paul Moore To: linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-audit@redhat.com, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, Kumar Kartikeya Dwivedi , Jens Axboe , Pavel Begunkov Date: Wed, 11 Aug 2021 16:49:01 -0400 Message-ID: <162871494177.63873.3490371261067398163.stgit@olly> In-Reply-To: <162871480969.63873.9434591871437326374.stgit@olly> References: <162871480969.63873.9434591871437326374.stgit@olly> User-Agent: StGit/1.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org WARNING - This is a work in progress, this patch, including the description, may be incomplete or even incorrect. You have been warned. This patch implements two new io_uring access controls, specifically support for controlling the io_uring "personalities" and IORING_SETUP_SQPOLL. Controlling the sharing of io_urings themselves is handled via the normal file/inode labeling and sharing mechanisms. The io_uring { override_creds } permission restricts which domains the subject domain can use to override it's own credentials. Granting a domain the io_uring { override_creds } permission allows it to impersonate another domain in io_uring operations. The io_uring { sqpoll } permission restricts which domains can create asynchronous io_uring polling threads. This is important from a security perspective as operations queued by this asynchronous thread inherit the credentials of the thread creator by default; if an io_uring is shared across process/domain boundaries this could result in one domain impersonating another. Controlling the creation of sqpoll threads, and the sharing of io_urings across processes, allow policy authors to restrict the ability of one domain to impersonate another via io_uring. As a quick summary, this patch adds a new object class with two permissions: io_uring { override_creds sqpoll } These permissions can be seen in the two simple policy statements below: allow domA_t domB_t : io_uring { override_creds }; allow domA_t self : io_uring { sqpoll }; Signed-off-by: Paul Moore --- v2: - made the selinux_uring_* funcs static - removed the debugging code v1: - initial draft --- security/selinux/hooks.c | 34 ++++++++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 2 files changed, 36 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index b0032c42333e..1fb0c76deff2 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -7105,6 +7105,35 @@ static int selinux_perf_event_write(struct perf_event *event) } #endif +#ifdef CONFIG_IO_URING +/** + * selinux_uring_override_creds - check the requested cred override + * @new: the target creds + * + * Check to see if the current task is allowed to override it's credentials + * to service an io_uring operation. + */ +static int selinux_uring_override_creds(const struct cred *new) +{ + return avc_has_perm(&selinux_state, current_sid(), cred_sid(new), + SECCLASS_IO_URING, IO_URING__OVERRIDE_CREDS, NULL); +} + +/** + * selinux_uring_sqpoll - check if a io_uring polling thread can be created + * + * Check to see if the current task is allowed to create a new io_uring + * kernel polling thread. + */ +static int selinux_uring_sqpoll(void) +{ + int sid = current_sid(); + + return avc_has_perm(&selinux_state, sid, sid, + SECCLASS_IO_URING, IO_URING__SQPOLL, NULL); +} +#endif /* CONFIG_IO_URING */ + /* * IMPORTANT NOTE: When adding new hooks, please be careful to keep this order: * 1. any hooks that don't belong to (2.) or (3.) below, @@ -7343,6 +7372,11 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(perf_event_write, selinux_perf_event_write), #endif +#ifdef CONFIG_IO_URING + LSM_HOOK_INIT(uring_override_creds, selinux_uring_override_creds), + LSM_HOOK_INIT(uring_sqpoll, selinux_uring_sqpoll), +#endif + LSM_HOOK_INIT(locked_down, selinux_lockdown), /* diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 62d19bccf3de..3314ad72279d 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -252,6 +252,8 @@ struct security_class_mapping secclass_map[] = { { "integrity", "confidentiality", NULL } }, { "anon_inode", { COMMON_FILE_PERMS, NULL } }, + { "io_uring", + { "override_creds", "sqpoll", NULL } }, { NULL } };