From patchwork Wed Jun 7 12:36:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13270646 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20132C87FE1 for ; Wed, 7 Jun 2023 12:37:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240349AbjFGMhZ (ORCPT ); Wed, 7 Jun 2023 08:37:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240817AbjFGMhK (ORCPT ); Wed, 7 Jun 2023 08:37:10 -0400 Received: from frasgout11.his.huawei.com (unknown [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65E45E6B; Wed, 7 Jun 2023 05:37:07 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.227]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4QbmmX19Rkz9xFQv; Wed, 7 Jun 2023 20:26:36 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwCnJgLMeYBkSckaAw--.4176S6; Wed, 07 Jun 2023 13:36:51 +0100 (CET) From: Roberto Sassu To: casey@schaufler-ca.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Roberto Sassu Subject: [RFC][PATCH 4/5] smack: Initialize the in-memory inode in smack_inode_init_security() Date: Wed, 7 Jun 2023 14:36:11 +0200 Message-Id: <20230607123612.2791303-5-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230607123612.2791303-1-roberto.sassu@huaweicloud.com> References: <20230607123612.2791303-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: LxC2BwCnJgLMeYBkSckaAw--.4176S6 X-Coremail-Antispam: 1UD129KBjvJXoWxCry8WFWfGF4kAw18GFW5Awb_yoW5Zw1xpF Zxt3W7KwnYyF97urW0yr47Ww1SkFWrKr4UGrZ8Jw17A3Zrtw1xKF1rXr45ZF15Xr4kZa1F va1j9ry3WFn0y3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBab4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwCY1x0262kKe7AKxVW8ZVWrXwCF04k20xvY0x 0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42IY 6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aV CY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07j7GYLUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAQABBF1jj45V3AAAsy X-CFilter-Loop: Reflected Precedence: bulk List-ID: From: Roberto Sassu Currently, Smack initializes in-memory new inodes in three steps. It first sets the xattrs in smack_inode_init_security(), fetches them in smack_d_instantiate() and finally, in the same function, sets the in-memory inodes depending on xattr values, unless they are in specially-handled filesystems. Other than being inefficient, this also prevents filesystems not supporting xattrs from working properly since, without xattrs, there is no way to pass the label determined in smack_inode_init_security() to smack_d_instantiate(). Since the LSM infrastructure allows setting and getting the security field without xattrs through the inode_setsecurity and inode_getsecurity hooks, make the inode creation work too, by initializing the in-memory inode earlier in smack_inode_init_security(). Also mark the inode as instantiated, to prevent smack_d_instantiate() from overwriting the security field. As mentioned above, this potentially has impact for inodes in specially-handled filesystems in smack_d_instantiate(), if they are not handled in the same way in smack_inode_init_security(). Filesystems other than tmpfs don't call security_inode_init_security(), so they would be always initialized in smack_d_instantiate(), as before. For tmpfs, the current behavior is to assign to inodes the label '*', but actually that label is overwritten with the one fetched from the SMACK64 xattr, set in smack_inode_init_security() (default: '_'). Initializing the in-memory inode is straightforward: if not transmuting, nothing more needs to be done; if transmuting, overwrite the current inode label with the one from the parent directory, and set SMK_INODE_TRANSMUTE. Finally, set SMK_INODE_INSTANT for all cases, to mark the inode as instantiated. Signed-off-by: Roberto Sassu --- security/smack/smack_lsm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index f7382448e12..1373c6d49ff 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -942,6 +942,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, struct xattr *xattrs, int *xattr_count) { struct task_smack *tsp = smack_cred(current_cred()); + struct inode_smack *issp = smack_inode(inode); struct smack_known *skp = smk_of_task(tsp); struct smack_known *isp = smk_of_inode(inode); struct smack_known *dsp = smk_of_inode(dir); @@ -977,7 +978,9 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, * smack_inode_alloc_security(). */ if (tsp->smk_task != tsp->smk_transmuted) - isp = dsp; + isp = issp->smk_inode = dsp; + + issp->smk_flags |= SMK_INODE_TRANSMUTE; xattr_transmute = lsm_get_xattr_slot(xattrs, xattr_count); if (xattr_transmute) { @@ -992,6 +995,8 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, } } + issp->smk_flags |= SMK_INODE_INSTANT; + if (xattr) { xattr->value = kstrdup(isp->smk_known, GFP_NOFS); if (xattr->value == NULL)