linux-kernel - [PATCH v2 17/25] security: Introduce inode_post_create

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Message-Id: <20230831104136.903180-18-roberto.sassu@huaweicloud.com>
Date:   Thu, 31 Aug 2023 12:41:28 +0200
From:   Roberto Sassu <roberto.sassu@...weicloud.com>
To:     viro@...iv.linux.org.uk, brauner@...nel.org,
        chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de,
        kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com,
        zohar@...ux.ibm.com, dmitry.kasatkin@...il.com,
        paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com,
        dhowells@...hat.com, jarkko@...nel.org,
        stephen.smalley.work@...il.com, eparis@...isplace.org,
        casey@...aufler-ca.com
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nfs@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        selinux@...r.kernel.org, Roberto Sassu <roberto.sassu@...wei.com>,
        Stefan Berger <stefanb@...ux.ibm.com>
Subject: [PATCH v2 17/25] security: Introduce inode_post_create_tmpfile hook

From: Roberto Sassu <roberto.sassu@...wei.com>

In preparation for moving IMA and EVM to the LSM infrastructure, introduce
the inode_post_create_tmpfile hook.

Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
---
 fs/namei.c                    |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  8 ++++++++
 security/security.c           | 18 ++++++++++++++++++
 4 files changed, 29 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index c8c4ab26b52a..efed0e1e93f5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3700,6 +3700,7 @@ static int vfs_tmpfile(struct mnt_idmap *idmap,
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	}
+	security_inode_post_create_tmpfile(idmap, dir, file, mode);
 	ima_post_create_tmpfile(idmap, dir, file, mode);
 	return 0;
 }
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index b1634b5de98c..9ae573b83737 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -121,6 +121,8 @@ LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode,
 	 const struct qstr *name, const struct inode *context_inode)
 LSM_HOOK(int, 0, inode_create, struct inode *dir, struct dentry *dentry,
 	 umode_t mode)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_create_tmpfile, struct mnt_idmap *idmap,
+	 struct inode *dir, struct file *file, umode_t mode)
 LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir,
 	 struct dentry *new_dentry)
 LSM_HOOK(int, 0, inode_unlink, struct inode *dir, struct dentry *dentry)
diff --git a/include/linux/security.h b/include/linux/security.h
index f210bd66e939..5f296761883f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -338,6 +338,9 @@ int security_inode_init_security_anon(struct inode *inode,
 				      const struct qstr *name,
 				      const struct inode *context_inode);
 int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode);
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *dir, struct file *file,
+					umode_t mode);
 int security_inode_link(struct dentry *old_dentry, struct inode *dir,
 			 struct dentry *new_dentry);
 int security_inode_unlink(struct inode *dir, struct dentry *dentry);
@@ -788,6 +791,11 @@ static inline int security_inode_create(struct inode *dir,
 	return 0;
 }
 
+static inline void
+security_inode_post_create_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
+				   struct file *file, umode_t mode)
+{ }
+
 static inline int security_inode_link(struct dentry *old_dentry,
 				       struct inode *dir,
 				       struct dentry *new_dentry)
diff --git a/security/security.c b/security/security.c
index 56c1c1e66fd1..e5acb11f6ebd 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1920,6 +1920,24 @@ int security_inode_create(struct inode *dir, struct dentry *dentry,
 }
 EXPORT_SYMBOL_GPL(security_inode_create);
 
+/**
+ * security_inode_post_create_tmpfile() - Update inode security field after creation of tmpfile
+ * @idmap: idmap of the mount
+ * @dir: the inode of the base directory
+ * @file: file descriptor of the new tmpfile
+ * @mode: the mode of the new tmpfile
+ *
+ * Update inode security field after a tmpfile has been created.
+ */
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *dir,
+					struct file *file, umode_t mode)
+{
+	if (unlikely(IS_PRIVATE(dir)))
+		return;
+	call_void_hook(inode_post_create_tmpfile, idmap, dir, file, mode);
+}
+
 /**
  * security_inode_link() - Check if creating a hard link is allowed
  * @old_dentry: existing file
-- 
2.34.1