From patchwork Wed Aug 11 20:49:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Moore X-Patchwork-Id: 12431963 X-Patchwork-Delegate: paul@paul-moore.com 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 CEFFCC4320E 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 B56646105A for ; Wed, 11 Aug 2021 20:49:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229991AbhHKUt4 (ORCPT ); Wed, 11 Aug 2021 16:49:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232201AbhHKUtj (ORCPT ); Wed, 11 Aug 2021 16:49:39 -0400 Received: from mail-qt1-x835.google.com (mail-qt1-x835.google.com [IPv6:2607:f8b0:4864:20::835]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CFB1C0617BE for ; Wed, 11 Aug 2021 13:49:10 -0700 (PDT) Received: by mail-qt1-x835.google.com with SMTP id l3so3199601qtk.10 for ; Wed, 11 Aug 2021 13:49:10 -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=fjm5E8jlur4ZmhZQt8sIor5EdCTxd31hgJPvTT515QA=; b=WcS9qkWmdAOR30pHBAqpZASMI8pexAv4ZejPT9DVJiSLOdCpb6K46er2oFtZiWlWtZ tq4bSWMOL5wUt4qPVCQbF2pZmx4yGyzNLDQsnNno6BVCdeRutOVJ1sDICvxDuB08M/V8 yRfB0Gn7rgH9g0ZPGNVudaTXUlLLLyGv7HaeyLlC4gpjCbVfTSjOjGehTAPhz4DPwr40 RSjZmj7KleWkJj0WpLExiFfUouIIq4bQ8n1bimK6Fy+Ur9hGJOFdGOPKA4BgedtLR/Cy 2guxpNsjCQPbhpry68M4H+/rZiaVdjDsgTMf69KagspAyOExEVg/CRgpAWdGHGM8JucC JlSQ== 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=fjm5E8jlur4ZmhZQt8sIor5EdCTxd31hgJPvTT515QA=; b=IkQpOH2/xmYyIJQAfYa5vq80dzbQxGN5FgwhJ3ECDATFxs9n6uYkGtLLlQY1h2AS6d C0hicV5r6TIp4w2pdia9bTRdvVDmUUJ8fJ+eaQSfRYZjNJxbraTx1UQrhkVfDFsCbC9F Zo0YZIHXmK3KIz7xVODfM5RZmV0gNJ1vAT7GEHLy+XI24q4IouZIF/en2M2gDTsCmDTG KIf6fjf33RKSyscGPkLt0WVfOV3bP9uz0XHb5h75vlGzax+pj+Gtrkd9Xg6dT9Ptq7zA xIcY55HnHtSDP462NoAwZUDhz/ng591TVQ+ODJTuYo0pchjF+cZKO/qS/Ni1P5iFe9ee lBYg== X-Gm-Message-State: AOAM532PewFgxfiqBhL0q7x4L9GpEOFa2JYReaLddMdh8l8QrP0HuSfB Wzvufm9Lj/FPSoBSn9QAvRe2 X-Google-Smtp-Source: ABdhPJxvrwP5BSOOajTVuXk7Z63HlSzq+KFtGBCu4Il3OS/cOqfAvjfLAuqSVvNcYQqCWND161FvaA== X-Received: by 2002:ac8:7770:: with SMTP id h16mr613425qtu.144.1628714949098; Wed, 11 Aug 2021 13:49:09 -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 a24sm190568qtj.43.2021.08.11.13.49.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Aug 2021 13:49:08 -0700 (PDT) Subject: [RFC PATCH v2 9/9] Smack: Brutalist io_uring support with debug 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 16:49:07 -0400 Message-ID: <162871494794.63873.18299137802334845525.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: selinux@vger.kernel.org From: Casey Schaufler Add Smack privilege checks for io_uring. Use CAP_MAC_OVERRIDE for the override_creds case and CAP_MAC_ADMIN for creating a polling thread. These choices are based on conjecture regarding the intent of the surrounding code. Signed-off-by: Casey Schaufler [PM: make the smack_uring_* funcs static] Signed-off-by: Paul Moore --- v2: - made the smack_uring_* funcs static v1: - initial draft --- security/smack/smack_lsm.c | 64 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 223a6da0e6dc..7fb094098f38 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4691,6 +4691,66 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode, return 0; } +#ifdef CONFIG_IO_URING +/** + * smack_uring_override_creds - Is io_uring cred override allowed? + * @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 smack_uring_override_creds(const struct cred *new) +{ + struct task_smack *tsp = smack_cred(current_cred()); + struct task_smack *nsp = smack_cred(new); + +#if 1 + if (tsp->smk_task == nsp->smk_task) + pr_info("%s: Smack matches %s\n", __func__, + tsp->smk_task->smk_known); + else + pr_info("%s: Smack override check %s to %s\n", __func__, + tsp->smk_task->smk_known, nsp->smk_task->smk_known); +#endif + /* + * Allow the degenerate case where the new Smack value is + * the same as the current Smack value. + */ + if (tsp->smk_task == nsp->smk_task) + return 0; + +#if 1 + pr_info("%s: Smack sqpoll %s\n", __func__, + smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred()) ? + "ok by Smack" : "disallowed (No CAP_MAC_OVERRIDE)"); +#endif + if (smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred())) + return 0; + + return -EPERM; +} + +/** + * smack_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 smack_uring_sqpoll(void) +{ +#if 1 + pr_info("%s: Smack new ring %s\n", __func__, + smack_privileged_cred(CAP_MAC_ADMIN, current_cred()) ? + "ok by Smack" : "disallowed (No CAP_MAC_ADMIN)"); +#endif + if (smack_privileged_cred(CAP_MAC_ADMIN, current_cred())) + return 0; + + return -EPERM; +} + +#endif /* CONFIG_IO_URING */ + struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = { .lbs_cred = sizeof(struct task_smack), .lbs_file = sizeof(struct smack_known *), @@ -4843,6 +4903,10 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up), LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr), LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as), +#ifdef CONFIG_IO_URING + LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds), + LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll), +#endif };