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// SPDX-License-Identifier: GPL-2.0
/* XSKMAP used for AF_XDP sockets
* Copyright(c) 2018 Intel Corporation.
*/
#include <linux/bpf.h>
#include <linux/capability.h>
#include <net/xdp_sock.h>
#include <linux/slab.h>
#include <linux/sched.h>
struct xsk_map {
struct bpf_map map;
struct xdp_sock **xsk_map;
struct list_head __percpu *flush_list;
};
static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
{
int cpu, err = -EINVAL;
struct xsk_map *m;
u64 cost;
if (!capable(CAP_NET_ADMIN))
return ERR_PTR(-EPERM);
if (attr->max_entries == 0 || attr->key_size != 4 ||
attr->value_size != 4 ||
attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
return ERR_PTR(-EINVAL);
m = kzalloc(sizeof(*m), GFP_USER);
if (!m)
return ERR_PTR(-ENOMEM);
bpf_map_init_from_attr(&m->map, attr);
cost = (u64)m->map.max_entries * sizeof(struct xdp_sock *);
cost += sizeof(struct list_head) * num_possible_cpus();
if (cost >= U32_MAX - PAGE_SIZE)
goto free_m;
m->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
/* Notice returns -EPERM on if map size is larger than memlock limit */
err = bpf_map_precharge_memlock(m->map.pages);
if (err)
goto free_m;
err = -ENOMEM;
m->flush_list = alloc_percpu(struct list_head);
if (!m->flush_list)
goto free_m;
for_each_possible_cpu(cpu)
INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu));
m->xsk_map = bpf_map_area_alloc(m->map.max_entries *
sizeof(struct xdp_sock *),
m->map.numa_node);
if (!m->xsk_map)
goto free_percpu;
return &m->map;
free_percpu:
free_percpu(m->flush_list);
free_m:
kfree(m);
return ERR_PTR(err);
}
static void xsk_map_free(struct bpf_map *map)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
int i;
synchronize_net();
for (i = 0; i < map->max_entries; i++) {
struct xdp_sock *xs;
xs = m->xsk_map[i];
if (!xs)
continue;
sock_put((struct sock *)xs);
}
free_percpu(m->flush_list);
bpf_map_area_free(m->xsk_map);
kfree(m);
}
static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
u32 index = key ? *(u32 *)key : U32_MAX;
u32 *next = next_key;
if (index >= m->map.max_entries) {
*next = 0;
return 0;
}
if (index == m->map.max_entries - 1)
return -ENOENT;
*next = index + 1;
return 0;
}
struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct xdp_sock *xs;
if (key >= map->max_entries)
return NULL;
xs = READ_ONCE(m->xsk_map[key]);
return xs;
}
int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
struct xdp_sock *xs)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct list_head *flush_list = this_cpu_ptr(m->flush_list);
int err;
err = xsk_rcv(xs, xdp);
if (err)
return err;
if (!xs->flush_node.prev)
list_add(&xs->flush_node, flush_list);
return 0;
}
void __xsk_map_flush(struct bpf_map *map)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct list_head *flush_list = this_cpu_ptr(m->flush_list);
struct xdp_sock *xs, *tmp;
list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
xsk_flush(xs);
__list_del(xs->flush_node.prev, xs->flush_node.next);
xs->flush_node.prev = NULL;
}
}
static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
{
return NULL;
}
static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
u32 i = *(u32 *)key, fd = *(u32 *)value;
struct xdp_sock *xs, *old_xs;
struct socket *sock;
int err;
if (unlikely(map_flags > BPF_EXIST))
return -EINVAL;
if (unlikely(i >= m->map.max_entries))
return -E2BIG;
if (unlikely(map_flags == BPF_NOEXIST))
return -EEXIST;
sock = sockfd_lookup(fd, &err);
if (!sock)
return err;
if (sock->sk->sk_family != PF_XDP) {
sockfd_put(sock);
return -EOPNOTSUPP;
}
xs = (struct xdp_sock *)sock->sk;
if (!xsk_is_setup_for_bpf_map(xs)) {
sockfd_put(sock);
return -EOPNOTSUPP;
}
sock_hold(sock->sk);
old_xs = xchg(&m->xsk_map[i], xs);
if (old_xs) {
/* Make sure we've flushed everything. */
synchronize_net();
sock_put((struct sock *)old_xs);
}
sockfd_put(sock);
return 0;
}
static int xsk_map_delete_elem(struct bpf_map *map, void *key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct xdp_sock *old_xs;
int k = *(u32 *)key;
if (k >= map->max_entries)
return -EINVAL;
old_xs = xchg(&m->xsk_map[k], NULL);
if (old_xs) {
/* Make sure we've flushed everything. */
synchronize_net();
sock_put((struct sock *)old_xs);
}
return 0;
}
const struct bpf_map_ops xsk_map_ops = {
.map_alloc = xsk_map_alloc,
.map_free = xsk_map_free,
.map_get_next_key = xsk_map_get_next_key,
.map_lookup_elem = xsk_map_lookup_elem,
.map_update_elem = xsk_map_update_elem,
.map_delete_elem = xsk_map_delete_elem,
};
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