introduce new LSM hooks where vfsmount is available.

Add new LSM hooks for path-based checks.  Call them on directory-modifying
operations at the points where we still know the vfsmount involved.

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

security/Kconfig

@@ -81,6 +81,15 @@ config SECURITY_NETWORK_XFRM
 	  IPSec.
 	  If you are unsure how to answer this question, answer N.
 
+config SECURITY_PATH
+	bool "Security hooks for pathname based access control"
+	depends on SECURITY
+	help
+	  This enables the security hooks for pathname based access control.
+	  If enabled, a security module can use these hooks to
+	  implement pathname based access controls.
+	  If you are unsure how to answer this question, answer N.
+
 config SECURITY_FILE_CAPABILITIES
 	bool "File POSIX Capabilities"
 	default n

security/capability.c

@@ -263,6 +263,53 @@ static void cap_inode_getsecid(const struct inode *inode, u32 *secid)
 	*secid = 0;
 }
 
+#ifdef CONFIG_SECURITY_PATH
+static int cap_path_mknod(struct path *dir, struct dentry *dentry, int mode,
+			  unsigned int dev)
+{
+	return 0;
+}
+
+static int cap_path_mkdir(struct path *dir, struct dentry *dentry, int mode)
+{
+	return 0;
+}
+
+static int cap_path_rmdir(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static int cap_path_unlink(struct path *dir, struct dentry *dentry)
+{
+	return 0;
+}
+
+static int cap_path_symlink(struct path *dir, struct dentry *dentry,
+			    const char *old_name)
+{
+	return 0;
+}
+
+static int cap_path_link(struct dentry *old_dentry, struct path *new_dir,
+			 struct dentry *new_dentry)
+{
+	return 0;
+}
+
+static int cap_path_rename(struct path *old_path, struct dentry *old_dentry,
+			   struct path *new_path, struct dentry *new_dentry)
+{
+	return 0;
+}
+
+static int cap_path_truncate(struct path *path, loff_t length,
+			     unsigned int time_attrs)
+{
+	return 0;
+}
+#endif
+
 static int cap_file_permission(struct file *file, int mask)
 {
 	return 0;
@@ -883,6 +930,16 @@ void security_fixup_ops(struct security_operations *ops)
 	set_to_cap_if_null(ops, inode_setsecurity);
 	set_to_cap_if_null(ops, inode_listsecurity);
 	set_to_cap_if_null(ops, inode_getsecid);
+#ifdef CONFIG_SECURITY_PATH
+	set_to_cap_if_null(ops, path_mknod);
+	set_to_cap_if_null(ops, path_mkdir);
+	set_to_cap_if_null(ops, path_rmdir);
+	set_to_cap_if_null(ops, path_unlink);
+	set_to_cap_if_null(ops, path_symlink);
+	set_to_cap_if_null(ops, path_link);
+	set_to_cap_if_null(ops, path_rename);
+	set_to_cap_if_null(ops, path_truncate);
+#endif
 	set_to_cap_if_null(ops, file_permission);
 	set_to_cap_if_null(ops, file_alloc_security);
 	set_to_cap_if_null(ops, file_free_security);

security/security.c

@@ -355,6 +355,72 @@ int security_inode_init_security(struct inode *inode, struct inode *dir,
 }
 EXPORT_SYMBOL(security_inode_init_security);
 
+#ifdef CONFIG_SECURITY_PATH
+int security_path_mknod(struct path *path, struct dentry *dentry, int mode,
+			unsigned int dev)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_mknod(path, dentry, mode, dev);
+}
+EXPORT_SYMBOL(security_path_mknod);
+
+int security_path_mkdir(struct path *path, struct dentry *dentry, int mode)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_mkdir(path, dentry, mode);
+}
+
+int security_path_rmdir(struct path *path, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_rmdir(path, dentry);
+}
+
+int security_path_unlink(struct path *path, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_unlink(path, dentry);
+}
+
+int security_path_symlink(struct path *path, struct dentry *dentry,
+			  const char *old_name)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_symlink(path, dentry, old_name);
+}
+
+int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+		       struct dentry *new_dentry)
+{
+	if (unlikely(IS_PRIVATE(old_dentry->d_inode)))
+		return 0;
+	return security_ops->path_link(old_dentry, new_dir, new_dentry);
+}
+
+int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+			 struct path *new_dir, struct dentry *new_dentry)
+{
+	if (unlikely(IS_PRIVATE(old_dentry->d_inode) ||
+		     (new_dentry->d_inode && IS_PRIVATE(new_dentry->d_inode))))
+		return 0;
+	return security_ops->path_rename(old_dir, old_dentry, new_dir,
+					 new_dentry);
+}
+
+int security_path_truncate(struct path *path, loff_t length,
+			   unsigned int time_attrs)
+{
+	if (unlikely(IS_PRIVATE(path->dentry->d_inode)))
+		return 0;
+	return security_ops->path_truncate(path, length, time_attrs);
+}
+#endif
+
 int security_inode_create(struct inode *dir, struct dentry *dentry, int mode)
 {
 	if (unlikely(IS_PRIVATE(dir)))