linux/security/apparmor/policy_ns.c
John Johansen 73688d1ed0 apparmor: refactor prepare_ns() and make usable from different views
prepare_ns() will need to be called from alternate views, and namespaces
will need to be created via different interfaces. So refactor and
allow specifying the view ns.

Signed-off-by: John Johansen <john.johansen@canonical.com>
2017-01-16 01:18:28 -08:00

346 lines
8.1 KiB
C

/*
* 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_ns *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)
* @subns: whether view of a subns is allowed
*
* Returns: true if @view is visible from @curr else false
*/
bool aa_ns_visible(struct aa_ns *curr, struct aa_ns *view, bool subns)
{
if (curr == view)
return true;
if (!subns)
return false;
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)
* @subns - are subns visible
*
* Returns: name of @view visible from @curr
*/
const char *aa_ns_name(struct aa_ns *curr, struct aa_ns *view, bool subns)
{
/* if view == curr then the namespace name isn't displayed */
if (curr == view)
return "";
if (aa_ns_visible(curr, view, subns)) {
/* 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_ns - 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_ns *alloc_ns(const char *prefix, const char *name)
{
struct aa_ns *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, GFP_KERNEL))
goto fail_ns;
INIT_LIST_HEAD(&ns->sub_ns);
mutex_init(&ns->lock);
/* released by aa_free_ns() */
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_ns - 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_ns(struct aa_ns *ns)
{
if (!ns)
return;
aa_policy_destroy(&ns->base);
aa_put_ns(ns->parent);
ns->unconfined->ns = NULL;
aa_free_profile(ns->unconfined);
kzfree(ns);
}
/**
* aa_findn_ns - look up a profile namespace on the namespace list
* @root: namespace to search in (NOT NULL)
* @name: name of namespace to find (NOT NULL)
* @n: length of @name
*
* Returns: a refcounted namespace on the list, or NULL if no namespace
* called @name exists.
*
* refcount released by caller
*/
struct aa_ns *aa_findn_ns(struct aa_ns *root, const char *name, size_t n)
{
struct aa_ns *ns = NULL;
rcu_read_lock();
ns = aa_get_ns(__aa_findn_ns(&root->sub_ns, name, n));
rcu_read_unlock();
return ns;
}
/**
* aa_find_ns - 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_ns *aa_find_ns(struct aa_ns *root, const char *name)
{
return aa_findn_ns(root, name, strlen(name));
}
static struct aa_ns *__aa_create_ns(struct aa_ns *parent, const char *name,
struct dentry *dir)
{
struct aa_ns *ns;
int error;
AA_BUG(!parent);
AA_BUG(!name);
AA_BUG(!mutex_is_locked(&parent->lock));
ns = alloc_ns(parent->base.hname, name);
if (!ns)
return NULL;
mutex_lock(&ns->lock);
error = __aa_fs_ns_mkdir(ns, ns_subns_dir(parent), name);
if (error) {
AA_ERROR("Failed to create interface for ns %s\n",
ns->base.name);
mutex_unlock(&ns->lock);
aa_free_ns(ns);
return ERR_PTR(error);
}
ns->parent = aa_get_ns(parent);
list_add_rcu(&ns->base.list, &parent->sub_ns);
/* add list ref */
aa_get_ns(ns);
mutex_unlock(&ns->lock);
return ns;
}
/**
* aa_create_ns - create an ns, fail if it already exists
* @parent: the parent of the namespace being created
* @name: the name of the namespace
* @dir: if not null the dir to put the ns entries in
*
* Returns: the a refcounted ns that has been add or an ERR_PTR
*/
struct aa_ns *__aa_find_or_create_ns(struct aa_ns *parent, const char *name,
struct dentry *dir)
{
struct aa_ns *ns;
AA_BUG(!mutex_is_locked(&parent->lock));
/* try and find the specified ns */
/* released by caller */
ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
if (!ns)
ns = __aa_create_ns(parent, name, dir);
else
ns = ERR_PTR(-EEXIST);
/* return ref */
return ns;
}
/**
* aa_prepare_ns - find an existing or create a new namespace of @name
* @parent: ns to treat as parent
* @name: the namespace to find or add (NOT NULL)
*
* Returns: refcounted namespace or PTR_ERR if failed to create one
*/
struct aa_ns *aa_prepare_ns(struct aa_ns *parent, const char *name)
{
struct aa_ns *ns;
mutex_lock(&parent->lock);
/* try and find the specified ns and if it doesn't exist create it */
/* released by caller */
ns = aa_get_ns(__aa_find_ns(&parent->sub_ns, name));
if (!ns)
ns = __aa_create_ns(parent, name, NULL);
mutex_unlock(&parent->lock);
/* return ref */
return ns;
}
static void __ns_list_release(struct list_head *head);
/**
* destroy_ns - remove everything contained by @ns
* @ns: namespace to have it contents removed (NOT NULL)
*/
static void destroy_ns(struct aa_ns *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_proxy(ns->unconfined, ns->parent->unconfined);
__aa_fs_ns_rmdir(ns);
mutex_unlock(&ns->lock);
}
/**
* __aa_remove_ns - 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_ns(struct aa_ns *ns)
{
/* remove ns from namespace list */
list_del_rcu(&ns->base.list);
destroy_ns(ns);
aa_put_ns(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_ns *ns, *tmp;
list_for_each_entry_safe(ns, tmp, head, base.list)
__aa_remove_ns(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_ns(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_ns *ns = root_ns;
root_ns = NULL;
destroy_ns(ns);
aa_put_ns(ns);
}