AppArmor: refactor securityfs to use structures

Use a file tree structure to represent the AppArmor securityfs.

Signed-off-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/apparmorfs.c

@@ -144,36 +144,103 @@ static const struct file_operations aa_fs_profile_remove = {
 
 /** Base file system setup **/
 
-static struct dentry *aa_fs_dentry __initdata;
+static struct aa_fs_entry aa_fs_entry_apparmor[] = {
+	AA_FS_FILE_FOPS(".load", 0640, &aa_fs_profile_load),
+	AA_FS_FILE_FOPS(".replace", 0640, &aa_fs_profile_replace),
+	AA_FS_FILE_FOPS(".remove", 0640, &aa_fs_profile_remove),
+	{ }
+};
 
-static void __init aafs_remove(const char *name)
-{
-	struct dentry *dentry;
+static struct aa_fs_entry aa_fs_entry =
+	AA_FS_DIR("apparmor", aa_fs_entry_apparmor);
 
-	dentry = lookup_one_len(name, aa_fs_dentry, strlen(name));
-	if (!IS_ERR(dentry)) {
-		securityfs_remove(dentry);
-		dput(dentry);
+/**
+ * aafs_create_file - create a file entry in the apparmor securityfs
+ * @fs_file: aa_fs_entry to build an entry for (NOT NULL)
+ * @parent: the parent dentry in the securityfs
+ *
+ * Use aafs_remove_file to remove entries created with this fn.
+ */
+static int __init aafs_create_file(struct aa_fs_entry *fs_file,
+				   struct dentry *parent)
+{
+	int error = 0;
+
+	fs_file->dentry = securityfs_create_file(fs_file->name,
+						 S_IFREG | fs_file->mode,
+						 parent, fs_file,
+						 fs_file->file_ops);
+	if (IS_ERR(fs_file->dentry)) {
+		error = PTR_ERR(fs_file->dentry);
+		fs_file->dentry = NULL;
 	}
+	return error;
 }
 
 /**
- * aafs_create - create an entry in the apparmor filesystem
- * @name: name of the entry (NOT NULL)
- * @mask: file permission mask of the file
- * @fops: file operations for the file (NOT NULL)
+ * aafs_create_dir - recursively create a directory entry in the securityfs
+ * @fs_dir: aa_fs_entry (and all child entries) to build (NOT NULL)
+ * @parent: the parent dentry in the securityfs
  *
- * Used aafs_remove to remove entries created with this fn.
+ * Use aafs_remove_dir to remove entries created with this fn.
  */
-static int __init aafs_create(const char *name, umode_t mask,
-			      const struct file_operations *fops)
+static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
+				  struct dentry *parent)
 {
-	struct dentry *dentry;
+	int error;
+	struct aa_fs_entry *fs_file;
 
-	dentry = securityfs_create_file(name, S_IFREG | mask, aa_fs_dentry,
-					NULL, fops);
+	fs_dir->dentry = securityfs_create_dir(fs_dir->name, parent);
+	if (IS_ERR(fs_dir->dentry)) {
+		error = PTR_ERR(fs_dir->dentry);
+		fs_dir->dentry = NULL;
+		goto failed;
+	}
 
-	return IS_ERR(dentry) ? PTR_ERR(dentry) : 0;
+	for (fs_file = fs_dir->v.files; fs_file->name; ++fs_file) {
+		if (fs_file->v_type == AA_FS_TYPE_DIR)
+			error = aafs_create_dir(fs_file, fs_dir->dentry);
+		else
+			error = aafs_create_file(fs_file, fs_dir->dentry);
+		if (error)
+			goto failed;
+	}
+
+	return 0;
+
+failed:
+	return error;
+}
+
+/**
+ * aafs_remove_file - drop a single file entry in the apparmor securityfs
+ * @fs_file: aa_fs_entry to detach from the securityfs (NOT NULL)
+ */
+static void __init aafs_remove_file(struct aa_fs_entry *fs_file)
+{
+	if (!fs_file->dentry)
+		return;
+
+	securityfs_remove(fs_file->dentry);
+	fs_file->dentry = NULL;
+}
+
+/**
+ * aafs_remove_dir - recursively drop a directory entry from the securityfs
+ * @fs_dir: aa_fs_entry (and all child entries) to detach (NOT NULL)
+ */
+static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir)
+{
+	struct aa_fs_entry *fs_file;
+
+	for (fs_file = fs_dir->v.files; fs_file->name; ++fs_file) {
+		if (fs_file->v_type == AA_FS_TYPE_DIR)
+			aafs_remove_dir(fs_file);
+		else
+			aafs_remove_file(fs_file);
+	}
+
+	aafs_remove_file(fs_dir);
 }
 
 /**
@@ -183,14 +250,7 @@ static int __init aafs_create(const char *name, umode_t mask,
  */
 void __init aa_destroy_aafs(void)
 {
-	if (aa_fs_dentry) {
-		aafs_remove(".remove");
-		aafs_remove(".replace");
-		aafs_remove(".load");
-
-		securityfs_remove(aa_fs_dentry);
-		aa_fs_dentry = NULL;
-	}
+	aafs_remove_dir(&aa_fs_entry);
 }
 
 /**
@@ -207,25 +267,13 @@ static int __init aa_create_aafs(void)
 	if (!apparmor_initialized)
 		return 0;
 
-	if (aa_fs_dentry) {
+	if (aa_fs_entry.dentry) {
 		AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
 		return -EEXIST;
 	}
 
-	aa_fs_dentry = securityfs_create_dir("apparmor", NULL);
-	if (IS_ERR(aa_fs_dentry)) {
-		error = PTR_ERR(aa_fs_dentry);
-		aa_fs_dentry = NULL;
-		goto error;
-	}
-
-	error = aafs_create(".load", 0640, &aa_fs_profile_load);
-	if (error)
-		goto error;
-	error = aafs_create(".replace", 0640, &aa_fs_profile_replace);
-	if (error)
-		goto error;
-	error = aafs_create(".remove", 0640, &aa_fs_profile_remove);
+	/* Populate fs tree. */
+	error = aafs_create_dir(&aa_fs_entry, NULL);
 	if (error)
 		goto error;
 

security/apparmor/include/apparmorfs.h

@@ -15,6 +15,30 @@
 #ifndef __AA_APPARMORFS_H
 #define __AA_APPARMORFS_H
 
+enum aa_fs_type {
+	AA_FS_TYPE_FOPS,
+	AA_FS_TYPE_DIR,
+};
+
+struct aa_fs_entry;
+
+struct aa_fs_entry {
+	const char *name;
+	struct dentry *dentry;
+	umode_t mode;
+	enum aa_fs_type v_type;
+	union {
+		struct aa_fs_entry *files;
+	} v;
+	const struct file_operations *file_ops;
+};
+
+#define AA_FS_FILE_FOPS(_name, _mode, _fops) \
+	{ .name = (_name), .v_type = AA_FS_TYPE_FOPS, \
+	  .mode = (_mode), .file_ops = (_fops) }
+#define AA_FS_DIR(_name, _value) \
+	{ .name = (_name), .v_type = AA_FS_TYPE_DIR, .v.files = (_value) }
+
 extern void __init aa_destroy_aafs(void);
 
 #endif /* __AA_APPARMORFS_H */