// 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);
                list_for_each_entry_safe(offmap, mtmp, &ondev->maps, offloads)
                        __bpf_map_offload_destroy(offmap);
        }

        WARN_ON(!list_empty(&ondev->progs));
        WARN_ON(!list_empty(&ondev->maps));
        kfree(ondev);
}

static int __bpf_prog_dev_bound_init(struct bpf_prog *prog, struct net_device *netdev)
{
        struct bpf_offload_netdev *ondev;
        struct bpf_prog_offload *offload;
        int err;

        offload = kzalloc_obj(*offload, GFP_USER);
        if (!offload)
                return -ENOMEM;

        offload->prog = prog;
        offload->netdev = netdev;

        ondev = bpf_offload_find_netdev(offload->netdev);
        /* When program is offloaded require presence of "true"
         * bpf_offload_netdev, avoid the one created for !ondev case below.
         */
        if (bpf_prog_is_offloaded(prog->aux) && (!ondev || !ondev->offdev)) {
                err = -EINVAL;
                goto err_free;
        }
        if (!ondev) {
                /* When only binding to the device, explicitly
                 * create an entry in the hashtable.
                 */
                err = __bpf_offload_dev_netdev_register(NULL, offload->netdev);
                if (err)
                        goto err_free;
                ondev = bpf_offload_find_netdev(offload->netdev);
        }
        offload->offdev = ondev->offdev;
        prog->aux->offload = offload;
        list_add_tail(&offload->offloads, &ondev->progs);

        return 0;
err_free:
        kfree(offload);
        return err;
}

int bpf_prog_dev_bound_init(struct bpf_prog *prog, union bpf_attr *attr)
{
        struct net_device *netdev;
        int err;

        if (attr->prog_type != BPF_PROG_TYPE_SCHED_CLS &&
            attr->prog_type != BPF_PROG_TYPE_XDP)
                return -EINVAL;

        if (attr->prog_flags & ~(BPF_F_XDP_DEV_BOUND_ONLY | BPF_F_XDP_HAS_FRAGS))
                return -EINVAL;

        /* Frags are allowed only if program is dev-bound-only, but not
         * if it is requesting bpf offload.
         */
        if (attr->prog_flags & BPF_F_XDP_HAS_FRAGS &&
            !(attr->prog_flags & BPF_F_XDP_DEV_BOUND_ONLY))
                return -EINVAL;

        if (attr->prog_type == BPF_PROG_TYPE_SCHED_CLS &&
            attr->prog_flags & BPF_F_XDP_DEV_BOUND_ONLY)
                return -EINVAL;

        netdev = dev_get_by_index(current->nsproxy->net_ns, attr->prog_ifindex);
        if (!netdev)
                return -EINVAL;

        err = bpf_dev_offload_check(netdev);
        if (err)
                goto out;

        prog->aux->offload_requested = !(attr->prog_flags & BPF_F_XDP_DEV_BOUND_ONLY);

        down_write(&bpf_devs_lock);
        err = __bpf_prog_dev_bound_init(prog, netdev);
        up_write(&bpf_devs_lock);

out:
        dev_put(netdev);
        return err;
}

int bpf_prog_dev_bound_inherit(struct bpf_prog *new_prog, struct bpf_prog *old_prog)
{
        int err;

        if (!bpf_prog_is_dev_bound(old_prog->aux))
                return 0;

        if (bpf_prog_is_offloaded(old_prog->aux))
                return -EINVAL;

        new_prog->aux->dev_bound = old_prog->aux->dev_bound;
        new_prog->aux->offload_requested = old_prog->aux->offload_requested;

        down_write(&bpf_devs_lock);
        if (!old_prog->aux->offload) {
                err = -EINVAL;
                goto out;
        }

        err = __bpf_prog_dev_bound_init(new_prog, old_prog->aux->offload->netdev);

out:
        up_write(&bpf_devs_lock);
        return err;
}

int bpf_prog_offload_verifier_prep(struct bpf_prog *prog)
{
        struct bpf_prog_offload *offload;
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        offload = prog->aux->offload;
        if (offload) {
                ret = offload->offdev->ops->prepare(prog);
                offload->dev_state = !ret;
        }
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
                                 int insn_idx, int prev_insn_idx)
{
        struct bpf_prog_offload *offload;
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        offload = env->prog->aux->offload;
        if (offload)
                ret = offload->offdev->ops->insn_hook(env, insn_idx,
                                                      prev_insn_idx);
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_prog_offload_finalize(struct bpf_verifier_env *env)
{
        struct bpf_prog_offload *offload;
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        offload = env->prog->aux->offload;
        if (offload) {
                if (offload->offdev->ops->finalize)
                        ret = offload->offdev->ops->finalize(env);
                else
                        ret = 0;
        }
        up_read(&bpf_devs_lock);

        return ret;
}

void
bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
                              struct bpf_insn *insn)
{
        const struct bpf_prog_offload_ops *ops;
        struct bpf_prog_offload *offload;
        int ret = -EOPNOTSUPP;

        down_read(&bpf_devs_lock);
        offload = env->prog->aux->offload;
        if (offload) {
                ops = offload->offdev->ops;
                if (!offload->opt_failed && ops->replace_insn)
                        ret = ops->replace_insn(env, off, insn);
                offload->opt_failed |= ret;
        }
        up_read(&bpf_devs_lock);
}

void
bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
        struct bpf_prog_offload *offload;
        int ret = -EOPNOTSUPP;

        down_read(&bpf_devs_lock);
        offload = env->prog->aux->offload;
        if (offload) {
                if (!offload->opt_failed && offload->offdev->ops->remove_insns)
                        ret = offload->offdev->ops->remove_insns(env, off, cnt);
                offload->opt_failed |= ret;
        }
        up_read(&bpf_devs_lock);
}

void bpf_prog_dev_bound_destroy(struct bpf_prog *prog)
{
        struct bpf_offload_netdev *ondev;
        struct net_device *netdev;

        rtnl_lock();
        down_write(&bpf_devs_lock);
        if (prog->aux->offload) {
                list_del_init(&prog->aux->offload->offloads);

                netdev = prog->aux->offload->netdev;
                __bpf_prog_offload_destroy(prog);

                ondev = bpf_offload_find_netdev(netdev);
                if (!ondev->offdev && list_empty(&ondev->progs))
                        __bpf_offload_dev_netdev_unregister(NULL, netdev);
        }
        up_write(&bpf_devs_lock);
        rtnl_unlock();
}

static int bpf_prog_offload_translate(struct bpf_prog *prog)
{
        struct bpf_prog_offload *offload;
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        offload = prog->aux->offload;
        if (offload)
                ret = offload->offdev->ops->translate(prog);
        up_read(&bpf_devs_lock);

        return ret;
}

static unsigned int bpf_prog_warn_on_exec(const void *ctx,
                                          const struct bpf_insn *insn)
{
        WARN(1, "attempt to execute device eBPF program on the host!");
        return 0;
}

int bpf_prog_offload_compile(struct bpf_prog *prog)
{
        prog->bpf_func = bpf_prog_warn_on_exec;

        return bpf_prog_offload_translate(prog);
}

struct ns_get_path_bpf_prog_args {
        struct bpf_prog *prog;
        struct bpf_prog_info *info;
};

static struct ns_common *bpf_prog_offload_info_fill_ns(void *private_data)
{
        struct ns_get_path_bpf_prog_args *args = private_data;
        struct bpf_prog_aux *aux = args->prog->aux;
        struct ns_common *ns;
        struct net *net;

        rtnl_lock();
        down_read(&bpf_devs_lock);

        if (aux->offload) {
                args->info->ifindex = aux->offload->netdev->ifindex;
                net = dev_net(aux->offload->netdev);
                get_net(net);
                ns = &net->ns;
        } else {
                args->info->ifindex = 0;
                ns = NULL;
        }

        up_read(&bpf_devs_lock);
        rtnl_unlock();

        return ns;
}

int bpf_prog_offload_info_fill(struct bpf_prog_info *info,
                               struct bpf_prog *prog)
{
        struct ns_get_path_bpf_prog_args args = {
                .prog   = prog,
                .info   = info,
        };
        struct bpf_prog_aux *aux = prog->aux;
        struct inode *ns_inode;
        struct path ns_path;
        char __user *uinsns;
        int res;
        u32 ulen;

        res = ns_get_path_cb(&ns_path, bpf_prog_offload_info_fill_ns, &args);
        if (res) {
                if (!info->ifindex)
                        return -ENODEV;
                return res;
        }

        down_read(&bpf_devs_lock);

        if (!aux->offload) {
                up_read(&bpf_devs_lock);
                return -ENODEV;
        }

        ulen = info->jited_prog_len;
        info->jited_prog_len = aux->offload->jited_len;
        if (info->jited_prog_len && ulen) {
                uinsns = u64_to_user_ptr(info->jited_prog_insns);
                ulen = min_t(u32, info->jited_prog_len, ulen);
                if (copy_to_user(uinsns, aux->offload->jited_image, ulen)) {
                        up_read(&bpf_devs_lock);
                        return -EFAULT;
                }
        }

        up_read(&bpf_devs_lock);

        ns_inode = ns_path.dentry->d_inode;
        info->netns_dev = new_encode_dev(ns_inode->i_sb->s_dev);
        info->netns_ino = ns_inode->i_ino;
        path_put(&ns_path);

        return 0;
}

const struct bpf_prog_ops bpf_offload_prog_ops = {
};

struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr)
{
        struct net *net = current->nsproxy->net_ns;
        struct bpf_offload_netdev *ondev;
        struct bpf_offloaded_map *offmap;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return ERR_PTR(-EPERM);
        if (attr->map_type != BPF_MAP_TYPE_ARRAY &&
            attr->map_type != BPF_MAP_TYPE_HASH)
                return ERR_PTR(-EINVAL);

        offmap = bpf_map_area_alloc(sizeof(*offmap), NUMA_NO_NODE);
        if (!offmap)
                return ERR_PTR(-ENOMEM);

        bpf_map_init_from_attr(&offmap->map, attr);
        rtnl_lock();
        offmap->netdev = __dev_get_by_index(net, attr->map_ifindex);
        err = bpf_dev_offload_check(offmap->netdev);
        if (err)
                goto err_unlock_rtnl;

        netdev_lock_ops(offmap->netdev);
        down_write(&bpf_devs_lock);

        ondev = bpf_offload_find_netdev(offmap->netdev);
        if (!ondev) {
                err = -EINVAL;
                goto err_unlock;
        }

        err = bpf_map_offload_ndo(offmap, BPF_OFFLOAD_MAP_ALLOC);
        if (err)
                goto err_unlock;

        list_add_tail(&offmap->offloads, &ondev->maps);
        up_write(&bpf_devs_lock);
        netdev_unlock_ops(offmap->netdev);
        rtnl_unlock();

        return &offmap->map;

err_unlock:
        up_write(&bpf_devs_lock);
        netdev_unlock_ops(offmap->netdev);
err_unlock_rtnl:
        rtnl_unlock();
        bpf_map_area_free(offmap);
        return ERR_PTR(err);
}

void bpf_map_offload_map_free(struct bpf_map *map)
{
        struct bpf_offloaded_map *offmap = map_to_offmap(map);

        rtnl_lock();
        down_write(&bpf_devs_lock);
        if (offmap->netdev)
                __bpf_map_offload_destroy(offmap);
        up_write(&bpf_devs_lock);
        rtnl_unlock();

        bpf_map_area_free(offmap);
}

u64 bpf_map_offload_map_mem_usage(const struct bpf_map *map)
{
        /* The memory dynamically allocated in netdev dev_ops is not counted */
        return sizeof(struct bpf_offloaded_map);
}

int bpf_map_offload_lookup_elem(struct bpf_map *map, void *key, void *value)
{
        struct bpf_offloaded_map *offmap = map_to_offmap(map);
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        if (offmap->netdev)
                ret = offmap->dev_ops->map_lookup_elem(offmap, key, value);
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_map_offload_update_elem(struct bpf_map *map,
                                void *key, void *value, u64 flags)
{
        struct bpf_offloaded_map *offmap = map_to_offmap(map);
        int ret = -ENODEV;

        if (unlikely(flags > BPF_EXIST))
                return -EINVAL;

        down_read(&bpf_devs_lock);
        if (offmap->netdev)
                ret = offmap->dev_ops->map_update_elem(offmap, key, value,
                                                       flags);
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_map_offload_delete_elem(struct bpf_map *map, void *key)
{
        struct bpf_offloaded_map *offmap = map_to_offmap(map);
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        if (offmap->netdev)
                ret = offmap->dev_ops->map_delete_elem(offmap, key);
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_map_offload_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
        struct bpf_offloaded_map *offmap = map_to_offmap(map);
        int ret = -ENODEV;

        down_read(&bpf_devs_lock);
        if (offmap->netdev)
                ret = offmap->dev_ops->map_get_next_key(offmap, key, next_key);
        up_read(&bpf_devs_lock);

        return ret;
}

struct ns_get_path_bpf_map_args {
        struct bpf_offloaded_map *offmap;
        struct bpf_map_info *info;
};

static struct ns_common *bpf_map_offload_info_fill_ns(void *private_data)
{
        struct ns_get_path_bpf_map_args *args = private_data;
        struct ns_common *ns;
        struct net *net;

        rtnl_lock();
        down_read(&bpf_devs_lock);

        if (args->offmap->netdev) {
                args->info->ifindex = args->offmap->netdev->ifindex;
                net = dev_net(args->offmap->netdev);
                get_net(net);
                ns = &net->ns;
        } else {
                args->info->ifindex = 0;
                ns = NULL;
        }

        up_read(&bpf_devs_lock);
        rtnl_unlock();

        return ns;
}

int bpf_map_offload_info_fill(struct bpf_map_info *info, struct bpf_map *map)
{
        struct ns_get_path_bpf_map_args args = {
                .offmap = map_to_offmap(map),
                .info   = info,
        };
        struct inode *ns_inode;
        struct path ns_path;
        int res;

        res = ns_get_path_cb(&ns_path, bpf_map_offload_info_fill_ns, &args);
        if (res) {
                if (!info->ifindex)
                        return -ENODEV;
                return res;
        }

        ns_inode = ns_path.dentry->d_inode;
        info->netns_dev = new_encode_dev(ns_inode->i_sb->s_dev);
        info->netns_ino = ns_inode->i_ino;
        path_put(&ns_path);

        return 0;
}

static bool __bpf_offload_dev_match(struct bpf_prog *prog,
                                    struct net_device *netdev)
{
        struct bpf_offload_netdev *ondev1, *ondev2;
        struct bpf_prog_offload *offload;

        if (!bpf_prog_is_dev_bound(prog->aux))
                return false;

        offload = prog->aux->offload;
        if (!offload)
                return false;
        if (offload->netdev == netdev)
                return true;

        ondev1 = bpf_offload_find_netdev(offload->netdev);
        ondev2 = bpf_offload_find_netdev(netdev);

        return ondev1 && ondev2 && ondev1->offdev == ondev2->offdev;
}

bool bpf_offload_dev_match(struct bpf_prog *prog, struct net_device *netdev)
{
        bool ret;

        down_read(&bpf_devs_lock);
        ret = __bpf_offload_dev_match(prog, netdev);
        up_read(&bpf_devs_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_match);

bool bpf_prog_dev_bound_match(const struct bpf_prog *lhs, const struct bpf_prog *rhs)
{
        bool ret;

        if (bpf_prog_is_offloaded(lhs->aux) != bpf_prog_is_offloaded(rhs->aux))
                return false;

        down_read(&bpf_devs_lock);
        ret = lhs->aux->offload && rhs->aux->offload &&
              lhs->aux->offload->netdev &&
              lhs->aux->offload->netdev == rhs->aux->offload->netdev;
        up_read(&bpf_devs_lock);

        return ret;
}

bool bpf_offload_prog_map_match(struct bpf_prog *prog, struct bpf_map *map)
{
        struct bpf_offloaded_map *offmap;
        bool ret;

        if (!bpf_map_is_offloaded(map))
                return bpf_map_offload_neutral(map);
        offmap = map_to_offmap(map);

        down_read(&bpf_devs_lock);
        ret = __bpf_offload_dev_match(prog, offmap->netdev);
        up_read(&bpf_devs_lock);

        return ret;
}

int bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
                                    struct net_device *netdev)
{
        int err;

        down_write(&bpf_devs_lock);
        err = __bpf_offload_dev_netdev_register(offdev, netdev);
        up_write(&bpf_devs_lock);
        return err;
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_register);

void bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
                                       struct net_device *netdev)
{
        down_write(&bpf_devs_lock);
        __bpf_offload_dev_netdev_unregister(offdev, netdev);
        up_write(&bpf_devs_lock);
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_netdev_unregister);

struct bpf_offload_dev *
bpf_offload_dev_create(const struct bpf_prog_offload_ops *ops, void *priv)
{
        struct bpf_offload_dev *offdev;

        offdev = kzalloc_obj(*offdev);
        if (!offdev)
                return ERR_PTR(-ENOMEM);

        offdev->ops = ops;
        offdev->priv = priv;
        INIT_LIST_HEAD(&offdev->netdevs);

        return offdev;
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_create);

void bpf_offload_dev_destroy(struct bpf_offload_dev *offdev)
{
        WARN_ON(!list_empty(&offdev->netdevs));
        kfree(offdev);
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_destroy);

void *bpf_offload_dev_priv(struct bpf_offload_dev *offdev)
{
        return offdev->priv;
}
EXPORT_SYMBOL_GPL(bpf_offload_dev_priv);

void bpf_dev_bound_netdev_unregister(struct net_device *dev)
{
        struct bpf_offload_netdev *ondev;

        ASSERT_RTNL();

        down_write(&bpf_devs_lock);
        ondev = bpf_offload_find_netdev(dev);
        if (ondev && !ondev->offdev)
                __bpf_offload_dev_netdev_unregister(NULL, ondev->netdev);
        up_write(&bpf_devs_lock);
}

int bpf_dev_bound_kfunc_check(struct bpf_verifier_log *log,
                              struct bpf_prog_aux *prog_aux)
{
        if (!bpf_prog_is_dev_bound(prog_aux)) {
                bpf_log(log, "metadata kfuncs require device-bound program\n");
                return -EINVAL;
        }

        if (bpf_prog_is_offloaded(prog_aux)) {
                bpf_log(log, "metadata kfuncs can't be offloaded\n");
                return -EINVAL;
        }

        return 0;
}

void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
{
        const struct xdp_metadata_ops *ops;
        void *p = NULL;

        /* We don't hold bpf_devs_lock while resolving several
         * kfuncs and can race with the unregister_netdevice().
         * We rely on bpf_dev_bound_match() check at attach
         * to render this program unusable.
         */
        down_read(&bpf_devs_lock);
        if (!prog->aux->offload)
                goto out;

        ops = prog->aux->offload->netdev->xdp_metadata_ops;
        if (!ops)
                goto out;

#define XDP_METADATA_KFUNC(name, _, __, xmo) \
        if (func_id == bpf_xdp_metadata_kfunc_id(name)) p = ops->xmo;
        XDP_METADATA_KFUNC_xxx
#undef XDP_METADATA_KFUNC

out:
        up_read(&bpf_devs_lock);

        return p;
}

static int __init bpf_offload_init(void)
{
        return rhashtable_init(&offdevs, &offdevs_params);
}

core_initcall(bpf_offload_init);