path: root/kernel/bpf/offload.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2017-2018 Netronome Systems, Inc.
 */

#include <linux/bpf.h>
#include <linux/bpf_verifier.h>
#include <linux/bug.h>
#include <linux/kdev_t.h>
#include <linux/list.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/printk.h>
#include <linux/proc_ns.h>
#include <linux/rhashtable.h>
#include <linux/rtnetlink.h>
#include <linux/rwsem.h>
#include <net/netdev_lock.h>
#include <net/xdp.h>

/* Protects offdevs, members of bpf_offload_netdev and offload members
 * of all progs.
 * RTNL lock cannot be taken when holding this lock.
 */
static DECLARE_RWSEM(bpf_devs_lock);

struct bpf_offload_dev {
	const struct bpf_prog_offload_ops *ops;
	struct list_head netdevs;
	void *priv;
};

struct bpf_offload_netdev {
	struct rhash_head l;
	struct net_device *netdev;
	struct bpf_offload_dev *offdev; /* NULL when bound-only */
	struct list_head progs;
	struct list_head maps;
	struct list_head offdev_netdevs;
};

static const struct rhashtable_params offdevs_params = {
	.nelem_hint		= 4,
	.key_len		= sizeof(struct net_device *),
	.key_offset		= offsetof(struct bpf_offload_netdev, netdev),
	.head_offset		= offsetof(struct bpf_offload_netdev, l),
	.automatic_shrinking	= true,
};

static struct rhashtable offdevs;

static int bpf_dev_offload_check(struct net_device *netdev)
{
	if (!netdev)
		return -EINVAL;
	if (!netdev->netdev_ops->ndo_bpf)
		return -EOPNOTSUPP;
	return 0;
}

static struct bpf_offload_netdev *
bpf_offload_find_netdev(struct net_device *netdev)
{
	lockdep_assert_held(&bpf_devs_lock);

	return rhashtable_lookup_fast(&offdevs, &netdev, offdevs_params);
}

static int __bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
					     struct net_device *netdev)
{
	struct bpf_offload_netdev *ondev;
	int err;

	ondev = kzalloc_obj(*ondev);
	if (!ondev)
		return -ENOMEM;

	ondev->netdev = netdev;
	ondev->offdev = offdev;
	INIT_LIST_HEAD(&ondev->progs);
	INIT_LIST_HEAD(&ondev->maps);

	err = rhashtable_insert_fast(&offdevs, &ondev->l, offdevs_params);
	if (err) {
		netdev_warn(netdev, "failed to register for BPF offload\n");
		goto err_free;
	}

	if (offdev)
		list_add(&ondev->offdev_netdevs, &offdev->netdevs);
	return 0;

err_free:
	kfree(ondev);
	return err;
}

static void __bpf_prog_offload_destroy(struct bpf_prog *prog)
{
	struct bpf_prog_offload *offload = prog->aux->offload;

	if (offload->dev_state)
		offload->offdev->ops->destroy(prog);

	list_del_init(&offload->offloads);
	kfree(offload);
	prog->aux->offload = NULL;
}

static int bpf_map_offload_ndo(struct bpf_offloaded_map *offmap,
			       enum bpf_netdev_command cmd)
{
	struct netdev_bpf data = {};
	struct net_device *netdev;

	ASSERT_RTNL();

	data.command = cmd;
	data.offmap = offmap;
	/* Caller must make sure netdev is valid */
	netdev = offmap->netdev;

	return netdev->netdev_ops->ndo_bpf(netdev, &data);
}

static void __bpf_map_offload_destroy(struct bpf_offloaded_map *offmap)
{
	WARN_ON(bpf_map_offload_ndo(offmap, BPF_OFFLOAD_MAP_FREE));
	/* Make sure BPF_MAP_GET_NEXT_ID can't find this dead map */
	bpf_map_free_id(&offmap->map);
	list_del_init(&offmap->offloads);
	offmap->netdev = NULL;
}

static void __bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
						struct net_device *netdev)
{
	struct bpf_offload_netdev *ondev, *altdev = NULL;
	struct bpf_offloaded_map *offmap, *mtmp;
	struct bpf_prog_offload *offload, *ptmp;

	ASSERT_RTNL();

	ondev = rhashtable_lookup_fast(&offdevs, &netdev, offdevs_params);
	if (WARN_ON(!ondev))
		return;

	WARN_ON(rhashtable_remove_fast(&offdevs, &ondev->l, offdevs_params));

	/* Try to move the objects to another netdev of the device */
	if (offdev) {
		list_del(&ondev->offdev_netdevs);
		altdev = list_first_entry_or_null(&offdev->netdevs,
						  struct bpf_offload_netdev,
						  offdev_netdevs);
	}

	if (altdev) {
		list_for_each_entry(offload, &ondev->progs, offloads)
			offload->netdev = altdev->netdev;
		list_splice_init(&ondev->progs, &altdev->progs);

		list_for_each_entry(offmap, &ondev->maps, offloads)
			offmap->netdev = altdev->netdev;
		list_splice_init(&ondev->maps, &altdev->maps);
	} else {
		list_for_each_entry_safe(offload, ptmp, &ondev->progs, offloads)
			__bpf_prog_offload_destroy(offload->prog