apparmor: split apparmor policy namespaces code into its own file

Policy namespaces will be diverging from profile management and
expanding so put it in its own file.

Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 291 insertions, 0 deletions

diff --git a/security/apparmor/policy_ns.c b/security/apparmor/policy_ns.c
new file mode 100644
index 000000000000..d4e9924a276e
--- /dev/null
+++ b/security/apparmor/policy_ns.c
@@ -0,0 +1,291 @@
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor policy manipulation functions
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2017 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ * AppArmor policy namespaces, allow for different sets of policies
+ * to be loaded for tasks within the namespace.
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "include/apparmor.h"
+#include "include/context.h"
+#include "include/policy_ns.h"
+#include "include/policy.h"
+
+/* root profile namespace */
+struct aa_namespace *root_ns;
+const char *aa_hidden_ns_name = "---";
+
+/**
+ * aa_ns_visible - test if @view is visible from @curr
+ * @curr: namespace to treat as the parent (NOT NULL)
+ * @view: namespace to test if visible from @curr (NOT NULL)
+ *
+ * Returns: true if @view is visible from @curr else false
+ */
+bool aa_ns_visible(struct aa_namespace *curr, struct aa_namespace *view)
+{
+	if (curr == view)
+		return true;
+
+	for ( ; view; view = view->parent) {
+		if (view->parent == curr)
+			return true;
+	}
+	return false;
+}
+
+/**
+ * aa_na_name - Find the ns name to display for @view from @curr
+ * @curr - current namespace (NOT NULL)
+ * @view - namespace attempting to view (NOT NULL)
+ *
+ * Returns: name of @view visible from @curr
+ */
+const char *aa_ns_name(struct aa_namespace *curr, struct aa_namespace *view)
+{
+	/* if view == curr then the namespace name isn't displayed */
+	if (curr == view)
+		return "";
+
+	if (aa_ns_visible(curr, view)) {
+		/* at this point if a ns is visible it is in a view ns
+		 * thus the curr ns.hname is a prefix of its name.
+		 * Only output the virtualized portion of the name
+		 * Add + 2 to skip over // separating curr hname prefix
+		 * from the visible tail of the views hname
+		 */
+		return view->base.hname + strlen(curr->base.hname) + 2;
+	}
+
+	return aa_hidden_ns_name;
+}
+
+/**
+ * alloc_namespace - allocate, initialize and return a new namespace
+ * @prefix: parent namespace name (MAYBE NULL)
+ * @name: a preallocated name  (NOT NULL)
+ *
+ * Returns: refcounted namespace or NULL on failure.
+ */
+static struct aa_namespace *alloc_namespace(const char *prefix,
+					    const char *name)
+{
+	struct aa_namespace *ns;
+
+	ns = kzalloc(sizeof(*ns), GFP_KERNEL);
+	AA_DEBUG("%s(%p)\n", __func__, ns);
+	if (!ns)
+		return NULL;
+	if (!aa_policy_init(&ns->base, prefix, name))
+		goto fail_ns;
+
+	INIT_LIST_HEAD(&ns->sub_ns);
+	mutex_init(&ns->lock);
+
+	/* released by free_namespace */
+	ns->unconfined = aa_alloc_profile("unconfined");
+	if (!ns->unconfined)
+		goto fail_unconfined;
+
+	ns->unconfined->flags = PFLAG_IX_ON_NAME_ERROR |
+		PFLAG_IMMUTABLE | PFLAG_NS_COUNT;
+	ns->unconfined->mode = APPARMOR_UNCONFINED;
+
+	/* ns and ns->unconfined share ns->unconfined refcount */
+	ns->unconfined->ns = ns;
+
+	atomic_set(&ns->uniq_null, 0);
+
+	return ns;
+
+fail_unconfined:
+	kzfree(ns->base.hname);
+fail_ns:
+	kzfree(ns);
+	return NULL;
+}
+
+/**
+ * aa_free_namespace - free a profile namespace
+ * @ns: the namespace to free  (MAYBE NULL)
+ *
+ * Requires: All references to the namespace must have been put, if the
+ *           namespace was referenced by a profile confining a task,
+ */
+void aa_free_namespace(struct aa_namespace *ns)
+{
+	if (!ns)
+		return;
+
+	aa_policy_destroy(&ns->base);
+	aa_put_namespace(ns->parent);
+
+	ns->unconfined->ns = NULL;
+	aa_free_profile(ns->unconfined);
+	kzfree(ns);
+}
+
+/**
+ * aa_find_namespace  -  look up a profile namespace on the namespace list
+ * @root: namespace to search in  (NOT NULL)
+ * @name: name of namespace to find  (NOT NULL)
+ *
+ * Returns: a refcounted namespace on the list, or NULL if no namespace
+ *          called @name exists.
+ *
+ * refcount released by caller
+ */
+struct aa_namespace *aa_find_namespace(struct aa_namespace *root,
+				       const char *name)
+{
+	struct aa_namespace *ns = NULL;
+
+	rcu_read_lock();
+	ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
+	rcu_read_unlock();
+
+	return ns;
+}
+
+/**
+ * aa_prepare_namespace - find an existing or create a new namespace of @name
+ * @name: the namespace to find or add  (MAYBE NULL)
+ *
+ * Returns: refcounted namespace or NULL if failed to create one
+ */
+struct aa_namespace *aa_prepare_namespace(const char *name)
+{
+	struct aa_namespace *ns, *root;
+
+	root = aa_current_profile()->ns;
+
+	mutex_lock(&root->lock);
+
+	/* if name isn't specified the profile is loaded to the current ns */
+	if (!name) {
+		/* released by caller */
+		ns = aa_get_namespace(root);
+		goto out;
+	}
+
+	/* try and find the specified ns and if it doesn't exist create it */
+	/* released by caller */
+	ns = aa_get_namespace(__aa_find_namespace(&root->sub_ns, name));
+	if (!ns) {
+		ns = alloc_namespace(root->base.hname, name);
+		if (!ns)
+			goto out;
+		if (__aa_fs_namespace_mkdir(ns, ns_subns_dir(root), name)) {
+			AA_ERROR("Failed to create interface for ns %s\n",
+				 ns->base.name);
+			aa_free_namespace(ns);
+			ns = NULL;
+			goto out;
+		}
+		ns->parent = aa_get_namespace(root);
+		list_add_rcu(&ns->base.list, &root->sub_ns);
+		/* add list ref */
+		aa_get_namespace(ns);
+	}
+out:
+	mutex_unlock(&root->lock);
+
+	/* return ref */
+	return ns;
+}
+
+static void __ns_list_release(struct list_head *head);
+
+/**
+ * destroy_namespace - remove everything contained by @ns
+ * @ns: namespace to have it contents removed  (NOT NULL)
+ */
+static void destroy_namespace(struct aa_namespace *ns)
+{
+	if (!ns)
+		return;
+
+	mutex_lock(&ns->lock);
+	/* release all profiles in this namespace */
+	__aa_profile_list_release(&ns->base.profiles);
+
+	/* release all sub namespaces */
+	__ns_list_release(&ns->sub_ns);
+
+	if (ns->parent)
+		__aa_update_replacedby(ns->unconfined, ns->parent->unconfined);
+	__aa_fs_namespace_rmdir(ns);
+	mutex_unlock(&ns->lock);
+}
+
+/**
+ * __aa_remove_namespace - remove a namespace and all its children
+ * @ns: namespace to be removed  (NOT NULL)
+ *
+ * Requires: ns->parent->lock be held and ns removed from parent.
+ */
+void __aa_remove_namespace(struct aa_namespace *ns)
+{
+	/* remove ns from namespace list */
+	list_del_rcu(&ns->base.list);
+	destroy_namespace(ns);
+	aa_put_namespace(ns);
+}
+
+/**
+ * __ns_list_release - remove all profile namespaces on the list put refs
+ * @head: list of profile namespaces  (NOT NULL)
+ *
+ * Requires: namespace lock be held
+ */
+static void __ns_list_release(struct list_head *head)
+{
+	struct aa_namespace *ns, *tmp;
+
+	list_for_each_entry_safe(ns, tmp, head, base.list)
+		__aa_remove_namespace(ns);
+
+}
+
+/**
+ * aa_alloc_root_ns - allocate the root profile namespace
+ *
+ * Returns: %0 on success else error
+ *
+ */
+int __init aa_alloc_root_ns(void)
+{
+	/* released by aa_free_root_ns - used as list ref*/
+	root_ns = alloc_namespace(NULL, "root");
+	if (!root_ns)
+		return -ENOMEM;
+
+	return 0;
+}
+
+ /**
+  * aa_free_root_ns - free the root profile namespace
+  */
+void __init aa_free_root_ns(void)
+{
+	 struct aa_namespace *ns = root_ns;
+
+	 root_ns = NULL;
+
+	 destroy_namespace(ns);
+	 aa_put_namespace(ns);
+}