From patchwork Mon Sep 4 13:34:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13373933 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 5060FC83F2C for ; Mon, 4 Sep 2023 13:38:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344917AbjIDNih (ORCPT ); Mon, 4 Sep 2023 09:38:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353115AbjIDNif (ORCPT ); Mon, 4 Sep 2023 09:38:35 -0400 Received: from frasgout12.his.huawei.com (unknown [14.137.139.154]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11F4410EB; Mon, 4 Sep 2023 06:38:11 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout12.his.huawei.com (SkyGuard) with ESMTP id 4RfTpp6cvZz9xHM1; Mon, 4 Sep 2023 21:23:14 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP1 (Coremail) with SMTP id LxC2BwDHerrf3PVkUqceAg--.16511S15; Mon, 04 Sep 2023 14:37:14 +0100 (CET) From: Roberto Sassu To: viro@zeniv.linux.org.uk, brauner@kernel.org, chuck.lever@oracle.com, jlayton@kernel.org, neilb@suse.de, kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, dhowells@redhat.com, jarkko@kernel.org, stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, selinux@vger.kernel.org, Roberto Sassu Subject: [PATCH v3 13/25] security: Introduce inode_post_removexattr hook Date: Mon, 4 Sep 2023 15:34:03 +0200 Message-Id: <20230904133415.1799503-14-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230904133415.1799503-1-roberto.sassu@huaweicloud.com> References: <20230904133415.1799503-1-roberto.sassu@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: LxC2BwDHerrf3PVkUqceAg--.16511S15 X-Coremail-Antispam: 1UD129KBjvJXoWxJw4rZw17KFykZr43Aw48Crg_yoWrAF48pF s8K3Z3Wr4rJFy7WryktF4Duw4I9FW3Wry7J3yIgw1IyFn7Jr1IqFZxCFyUCry5JrWjgr1q qFnFkrs8Cr15Jw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBvb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E 14v26r4UJVWxJr1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrV C2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE 7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCF04k20x vY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I 3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_WrylIxkGc2Ij64vIr41lIx AIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI 42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z2 80aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07UZo7tUUUUU= X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAKBF1jj4+BVwADsn X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org From: Roberto Sassu In preparation for moving IMA and EVM to the LSM infrastructure, introduce the inode_post_removexattr hook. It is useful for EVM to recalculate the HMAC on the remaining file xattrs, and other file metadata, after it verified the HMAC of current file metadata with the inode_removexattr hook. LSMs should use the new hook instead of inode_removexattr, when they need to know that the operation was done successfully (not known in inode_removexattr). The new hook cannot return an error and cannot cause the operation to be reverted. Signed-off-by: Roberto Sassu Reviewed-by: Stefan Berger Reviewed-by: Mimi Zohar --- fs/xattr.c | 9 +++++---- include/linux/lsm_hook_defs.h | 2 ++ include/linux/security.h | 5 +++++ security/security.c | 14 ++++++++++++++ 4 files changed, 26 insertions(+), 4 deletions(-) diff --git a/fs/xattr.c b/fs/xattr.c index e7bbb7f57557..4a0280295686 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -552,11 +552,12 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap, goto out; error = __vfs_removexattr(idmap, dentry, name); + if (error) + goto out; - if (!error) { - fsnotify_xattr(dentry); - evm_inode_post_removexattr(dentry, name); - } + fsnotify_xattr(dentry); + security_inode_post_removexattr(dentry, name); + evm_inode_post_removexattr(dentry, name); out: return error; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 995d30336cfa..1153e7163b8b 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -148,6 +148,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name) +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, + const char *name) LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap, diff --git a/include/linux/security.h b/include/linux/security.h index 820899db5276..665bba3e0081 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -374,6 +374,7 @@ int security_inode_getxattr(struct dentry *dentry, const char *name); int security_inode_listxattr(struct dentry *dentry); int security_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name); +void security_inode_post_removexattr(struct dentry *dentry, const char *name); int security_inode_need_killpriv(struct dentry *dentry); int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); int security_inode_getsecurity(struct mnt_idmap *idmap, @@ -919,6 +920,10 @@ static inline int security_inode_removexattr(struct mnt_idmap *idmap, return cap_inode_removexattr(idmap, dentry, name); } +static inline void security_inode_post_removexattr(struct dentry *dentry, + const char *name) +{ } + static inline int security_inode_need_killpriv(struct dentry *dentry) { return cap_inode_need_killpriv(dentry); diff --git a/security/security.c b/security/security.c index 764a6f28b3b9..3947159ba5e9 100644 --- a/security/security.c +++ b/security/security.c @@ -2354,6 +2354,20 @@ int security_inode_removexattr(struct mnt_idmap *idmap, return evm_inode_removexattr(idmap, dentry, name); } +/** + * security_inode_post_removexattr() - Update the inode after a removexattr op + * @dentry: file + * @name: xattr name + * + * Update the inode after a successful removexattr operation. + */ +void security_inode_post_removexattr(struct dentry *dentry, const char *name) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(inode_post_removexattr, dentry, name); +} + /** * security_inode_need_killpriv() - Check if security_inode_killpriv() required * @dentry: associated dentry