From patchwork Tue Sep 14 03:33:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Moore X-Patchwork-Id: 12491605 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 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 CBC02C433EF for ; Tue, 14 Sep 2021 03:34:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8B80610EA for ; Tue, 14 Sep 2021 03:34:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239115AbhINDfP (ORCPT ); Mon, 13 Sep 2021 23:35:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239179AbhINDfC (ORCPT ); Mon, 13 Sep 2021 23:35:02 -0400 Received: from mail-qk1-x72b.google.com (mail-qk1-x72b.google.com [IPv6:2607:f8b0:4864:20::72b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55EB5C0613E4 for ; Mon, 13 Sep 2021 20:33:43 -0700 (PDT) Received: by mail-qk1-x72b.google.com with SMTP id ay33so13174895qkb.10 for ; Mon, 13 Sep 2021 20:33:43 -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=54Sbzge3G+aat3VcychMMrLelhIpqQAZp6yuJG+ykt8=; b=aZ6thOvMHLr+wxTevjEA1i5Ht/W/KrKBQJDrsm43lV+2/eSbhr0/w/m5LaTbRZv97v 13VV/f6a5EZn+YwNo+evAqqV68Rk0Q3ZSZ7p66Z50xOHLmTvSRidUUAQqWKoRmufA//s TRdH5DrwLc8h6Fex7ElS7A8hxXq9SCFZnCMT2WXwEZFLdqa6eaRHhZuYOqmQZA+UPyb8 U6kNemODgsXPNN7mcEVByROU8emfLbr8Vnk/Yuyf9KR1xQgvIKEYcEbjkCJLJqdNEz8k K9dZzuNqP701EebgEt1oQ05r+hhjxT6DR0Y1fY8t9nmU0Lbxbb7cA5vBOG5ann40QGgU C7rg== 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=54Sbzge3G+aat3VcychMMrLelhIpqQAZp6yuJG+ykt8=; b=rxlPpsS9fa7vYcguFdUR/lUfkPBwWI50fXFAQU7O1D13P+lh7CNyqREMgyQuCMzCyI W+b4oXRCHt/zYA4nw6uSvDH0Bza+PKSdsS2OifkdBRMJ3kKAzYCR49Rzv/TdFF1UAQ6G p7C6iVkPit6BZ1FCgFSdbuIHZEOViiHn7GArHGvew6sEXY2ssx8P4ilrx4xg1H6q7/rv +ZDM/MHvghU9hLmfVAptcuuZxi9PJBUqOENI4dibacZiRqw/s117DVCRgoqLX3VvObwe TyapaVuduszB0NESVWt6YKpGDFnqOfFIU/bgo686W6K1tsK5Ltnhje/JbodX/Lnkx++K Tbmw== X-Gm-Message-State: AOAM530HoZvFanFAoTXIj9rFFDYVgpxmds24pMbUqxBJOHNPeaDTFdNj axOl/8PPO7c6WcwBzCzNQyjdloJSSw/n X-Google-Smtp-Source: ABdhPJxCTwAyD5dWI5ou1pL9SVHqbRt3WXQyP3KXoalYRryIJkcZ1TtZ+jPi+4HNVU0jJ4AhyxpGgA== X-Received: by 2002:a37:6691:: with SMTP id a139mr2900014qkc.310.1631590422163; Mon, 13 Sep 2021 20:33:42 -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 b1sm5212672qtj.76.2021.09.13.20.33.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Sep 2021 20:33:41 -0700 (PDT) Subject: [PATCH v3 8/8] 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, Jens Axboe , Pavel Begunkov , Kumar Kartikeya Dwivedi Date: Mon, 13 Sep 2021 23:33:41 -0400 Message-ID: <163159042110.470089.9405201508228711833.stgit@olly> In-Reply-To: <163159032713.470089.11728103630366176255.stgit@olly> References: <163159032713.470089.11728103630366176255.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 --- 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 };