From patchwork Wed Sep 15 16:50:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Moore X-Patchwork-Id: 12496875 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=-13.7 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 1BC9EC433EF for ; Wed, 15 Sep 2021 16:50:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04DE66121F for ; Wed, 15 Sep 2021 16:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230470AbhIOQvc (ORCPT ); Wed, 15 Sep 2021 12:51:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230443AbhIOQva (ORCPT ); Wed, 15 Sep 2021 12:51:30 -0400 Received: from mail-qv1-xf35.google.com (mail-qv1-xf35.google.com [IPv6:2607:f8b0:4864:20::f35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 121F1C061767 for ; Wed, 15 Sep 2021 09:50:11 -0700 (PDT) Received: by mail-qv1-xf35.google.com with SMTP id w8so2323246qvt.0 for ; Wed, 15 Sep 2021 09:50:11 -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=znV6h22uLT4tju8GfDCyoAJth/iE5nhq2gX552Nh+J8=; b=yR4M9FMq5YkZZZnLVBGoHE8n/L7LBcuRYu45AIK6rpu6q86Bt8q97V42UpmZakk9Hk qy1Abyuha691Im0rYc9EK/tOxPEZ+1p++dVyuU49SBOnF3DsCPgp/ECkkaOcSk9hOYg9 uZwNWDENAneb/b3kwwfPpFtKTclqgTySmd7avIWwSBqFJauyZ+YBc6bH4I/Gmz4clP5w UOG2/ZoGWt1ti8+ruNUFKiGZJPPEEa2XjAF0DA2xVI/cJ3BaH4r06uP8JDKIZQ63Cap9 ayT/rIEu7My8B35KdwQFfy0AsExXY/vMA5Y0BemiwrEF4O/6W75CvXEWvQeBY3Bhk5kO rFyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:from:to:date:message-id:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=znV6h22uLT4tju8GfDCyoAJth/iE5nhq2gX552Nh+J8=; b=kikBUKJw82YVlqOf22Ci/h61IAAkOwmCDcOMbAGMVQGR7tQgvdjxa0fYK1ZU9SFQ1f PpsERstgdN01WCeaDJgx9A+sG9wgCc9Z3Cv57s69aMpeN63yInMr+C+jiZz7HyF0fkKv XsUifYcGb3m8luoW8Z1HURYXj/f2gziiuGI0AyNUx+EtxCEZkMbY36aiDy8xERHqh2u9 Or5UbP5BmPfUv2ilZLO7NSEqhLOTUspYUE626rAgrkz7prUhtPwQeIWKm0T16d8FTu5/ q1ALzMin5/s3D/QAHPxaQWDnBA6bonngjkAHhSXeNk6OP2IHotg8SfofECcsEHy5k8Sf GxiA== X-Gm-Message-State: AOAM531jKr0Wp0mafZl4UHJEX7WbQFi/MqMwbwET+IhYJRWMUtKpsZ4u oNK8Jp0+655+yMHovQD8TJztCteoQgEv X-Google-Smtp-Source: ABdhPJx75T0dQPzt4WSic6uHD74Uop3/gZqSo+/ev3KVEiS5rzNOA3M5qoWYDRrYR2z4q+uilRE4LA== X-Received: by 2002:a05:6214:1394:: with SMTP id g20mr812980qvz.21.1631724609746; Wed, 15 Sep 2021 09:50:09 -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 w20sm377308qkj.116.2021.09.15.09.50.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Sep 2021 09:50:09 -0700 (PDT) Subject: [PATCH v4 8/8] Smack: Brutalist io_uring support 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, Jens Axboe , Pavel Begunkov , Kumar Kartikeya Dwivedi Date: Wed, 15 Sep 2021 12:50:08 -0400 Message-ID: <163172460848.88001.15344229885190060624.stgit@olly> In-Reply-To: <163172413301.88001.16054830862146685573.stgit@olly> References: <163172413301.88001.16054830862146685573.stgit@olly> User-Agent: StGit/1.1 MIME-Version: 1.0 Precedence: bulk List-ID: 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, remove debug code] Signed-off-by: Paul Moore --- v4: - updated subject line v3: - removed debug code v2: - made the smack_uring_* funcs static v1: - initial draft --- security/smack/smack_lsm.c | 46 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index cacbe7518519..f90ab1efeb6d 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4691,6 +4691,48 @@ 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); + + /* + * 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 (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 (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 +4885,10 @@ 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 };