From patchwork Mon Nov 20 17:33:03 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 13461724 Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from frasgout11.his.huawei.com (frasgout11.his.huawei.com [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD412C3; Mon, 20 Nov 2023 09:37:27 -0800 (PST) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4SYvVr4G6Lz9xvh2; Tue, 21 Nov 2023 01:23:48 +0800 (CST) Received: from huaweicloud.com (unknown [10.204.63.22]) by APP2 (Coremail) with SMTP id GxC2BwAHuGEqmVtlz4kHAQ--.4148S2; Mon, 20 Nov 2023 18:36:58 +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, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, dhowells@redhat.com, jarkko@kernel.org, stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com, mic@digikod.net Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, keyrings@vger.kernel.org, selinux@vger.kernel.org, Roberto Sassu , Stefan Berger Subject: [PATCH v6 10/25] security: Introduce inode_post_setattr hook Date: Mon, 20 Nov 2023 18:33:03 +0100 Message-Id: <20231120173318.1132868-11-roberto.sassu@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231120173318.1132868-1-roberto.sassu@huaweicloud.com> References: <20231120173318.1132868-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: keyrings@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: GxC2BwAHuGEqmVtlz4kHAQ--.4148S2 X-Coremail-Antispam: 1UD129KBjvJXoWxurykAw17WFW5XF48Cw18AFb_yoWrAr15pF WrK3WDKw4rWFW7WrykJF47ua1SgFy5urWUXrWqgwn0yFn7tw1aqF43Ka4jkr13GrW8Gr9I q3ZFvrsxCr15AwUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvSb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Cr1j6rxdM28EF7xvwVC2z280aVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVCY1x 0267AKxVWxJr0_GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8C rVC2j2WlYx0E2Ix0cI8IcVAFwI0_JF0_Jw1lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4 IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACI402YVCY1x02628vn2kIc2xKxwCY1x02 62kKe7AKxVW8ZVWrXwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s 026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_ GFv_WrylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW5JVW7JwCI42IY6xIIjxv20x vEc7CjxVAFwI0_Cr1j6rxdMIIF0xvE42xK8VAvwI8IcIk0rVW3JVWrJr1lIxAIcVC2z280 aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AKxVWxJr0_GcJvcSsGvfC2KfnxnUUI43 ZEXa7IU07UUUUUUUU== X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAHBF1jj5KqaQADsi X-CFilter-Loop: Reflected From: Roberto Sassu In preparation for moving IMA and EVM to the LSM infrastructure, introduce the inode_post_setattr hook. At inode_setattr hook, EVM verifies the file's existing HMAC value. At inode_post_setattr, EVM re-calculates the file's HMAC based on the modified file attributes and other file metadata. Other LSMs could similarly take some action after successful file attribute change. 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 Acked-by: Casey Schaufler --- fs/attr.c | 1 + include/linux/lsm_hook_defs.h | 2 ++ include/linux/security.h | 7 +++++++ security/security.c | 16 ++++++++++++++++ 4 files changed, 26 insertions(+) diff --git a/fs/attr.c b/fs/attr.c index 498e673bdf06..221d2bb0a906 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -502,6 +502,7 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry, if (!error) { fsnotify_change(dentry, ia_valid); + security_inode_post_setattr(idmap, dentry, ia_valid); ima_inode_post_setattr(idmap, dentry, ia_valid); evm_inode_post_setattr(idmap, dentry, ia_valid); } diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 752ed8a4f3c6..091cddb4e6de 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -137,6 +137,8 @@ LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode, LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask) LSM_HOOK(int, 0, inode_setattr, struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) +LSM_HOOK(void, LSM_RET_VOID, inode_post_setattr, struct mnt_idmap *idmap, + struct dentry *dentry, int ia_valid) LSM_HOOK(int, 0, inode_getattr, const struct path *path) LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name, const void *value, diff --git a/include/linux/security.h b/include/linux/security.h index 750130a7b9dd..664df46b22a9 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -361,6 +361,8 @@ int security_inode_follow_link(struct dentry *dentry, struct inode *inode, int security_inode_permission(struct inode *inode, int mask); int security_inode_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr); +void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid); int security_inode_getattr(const struct path *path); int security_inode_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name, @@ -877,6 +879,11 @@ static inline int security_inode_setattr(struct mnt_idmap *idmap, return 0; } +static inline void +security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid) +{ } + static inline int security_inode_getattr(const struct path *path) { return 0; diff --git a/security/security.c b/security/security.c index 7935d11d58b5..ce3bc7642e18 100644 --- a/security/security.c +++ b/security/security.c @@ -2222,6 +2222,22 @@ int security_inode_setattr(struct mnt_idmap *idmap, } EXPORT_SYMBOL_GPL(security_inode_setattr); +/** + * security_inode_post_setattr() - Update the inode after a setattr operation + * @idmap: idmap of the mount + * @dentry: file + * @ia_valid: file attributes set + * + * Update inode security field after successful setting file attributes. + */ +void security_inode_post_setattr(struct mnt_idmap *idmap, struct dentry *dentry, + int ia_valid) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(inode_post_setattr, idmap, dentry, ia_valid); +} + /** * security_inode_getattr() - Check if getting file attributes is allowed * @path: file