kernel/bpf/xskmap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* XSKMAP used for AF_XDP sockets
   3  * Copyright(c) 2018 Intel Corporation.
   4  */
   5
   6 #include <linux/bpf.h>
   7 #include <linux/capability.h>
   8 #include <net/xdp_sock.h>
   9 #include <linux/slab.h>
  10 #include <linux/sched.h>
  11
  12 struct xsk_map {
  13         struct bpf_map map;
  14         struct xdp_sock **xsk_map;
  15         struct list_head __percpu *flush_list;
  16 };
  17
  18 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
  19 {
  20         int cpu, err = -EINVAL;
  21         struct xsk_map *m;
  22         u64 cost;
  23
  24         if (!capable(CAP_NET_ADMIN))
  25                 return ERR_PTR(-EPERM);
  26
  27         if (attr->max_entries == 0 || attr->key_size != 4 ||
  28             attr->value_size != 4 ||
  29             attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
  30                 return ERR_PTR(-EINVAL);
  31
  32         m = kzalloc(sizeof(*m), GFP_USER);
  33         if (!m)
  34                 return ERR_PTR(-ENOMEM);
  35
  36         bpf_map_init_from_attr(&m->map, attr);
  37
  38         cost = (u64)m->map.max_entries * sizeof(struct xdp_sock *);
  39         cost += sizeof(struct list_head) * num_possible_cpus();
  40         if (cost >= U32_MAX - PAGE_SIZE)
  41                 goto free_m;
  42
  43         m->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
  44
  45         /* Notice returns -EPERM on if map size is larger than memlock limit */
  46         err = bpf_map_precharge_memlock(m->map.pages);
  47         if (err)
  48                 goto free_m;
  49
  50         err = -ENOMEM;
  51
  52         m->flush_list = alloc_percpu(struct list_head);
  53         if (!m->flush_list)
  54                 goto free_m;
  55
  56         for_each_possible_cpu(cpu)
  57                 INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu));
  58
  59         m->xsk_map = bpf_map_area_alloc(m->map.max_entries *
  60                                         sizeof(struct xdp_sock *),
  61                                         m->map.numa_node);
  62         if (!m->xsk_map)
  63                 goto free_percpu;
  64         return &m->map;
  65
  66 free_percpu:
  67         free_percpu(m->flush_list);
  68 free_m:
  69         kfree(m);
  70         return ERR_PTR(err);
  71 }
  72
  73 static void xsk_map_free(struct bpf_map *map)
  74 {
  75         struct xsk_map *m = container_of(map, struct xsk_map, map);
  76         int i;
  77
  78         bpf_clear_redirect_map(map);
  79         synchronize_net();
  80
  81         for (i = 0; i < map->max_entries; i++) {
  82                 struct xdp_sock *xs;
  83
  84                 xs = m->xsk_map[i];
  85                 if (!xs)
  86                         continue;
  87
  88                 sock_put((struct sock *)xs);
  89         }
  90
  91         free_percpu(m->flush_list);
  92         bpf_map_area_free(m->xsk_map);
  93         kfree(m);
  94 }
  95
  96 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
  97 {
  98         struct xsk_map *m = container_of(map, struct xsk_map, map);
  99         u32 index = key ? *(u32 *)key : U32_MAX;
 100         u32 *next = next_key;
 101
 102         if (index >= m->map.max_entries) {
 103                 *next = 0;
 104                 return 0;
 105         }
 106
 107         if (index == m->map.max_entries - 1)
 108                 return -ENOENT;
 109         *next = index + 1;
 110         return 0;
 111 }
 112
 113 struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
 114 {
 115         struct xsk_map *m = container_of(map, struct xsk_map, map);
 116         struct xdp_sock *xs;
 117
 118         if (key >= map->max_entries)
 119                 return NULL;
 120
 121         xs = READ_ONCE(m->xsk_map[key]);
 122         return xs;
 123 }
 124
 125 int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
 126                        struct xdp_sock *xs)
 127 {
 128         struct xsk_map *m = container_of(map, struct xsk_map, map);
 129         struct list_head *flush_list = this_cpu_ptr(m->flush_list);
 130         int err;
 131
 132         err = xsk_rcv(xs, xdp);
 133         if (err)
 134                 return err;
 135
 136         if (!xs->flush_node.prev)
 137                 list_add(&xs->flush_node, flush_list);
 138
 139         return 0;
 140 }
 141
 142 void __xsk_map_flush(struct bpf_map *map)
 143 {
 144         struct xsk_map *m = container_of(map, struct xsk_map, map);
 145         struct list_head *flush_list = this_cpu_ptr(m->flush_list);
 146         struct xdp_sock *xs, *tmp;
 147
 148         list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
 149                 xsk_flush(xs);
 150                 __list_del(xs->flush_node.prev, xs->flush_node.next);
 151                 xs->flush_node.prev = NULL;
 152         }
 153 }
 154
 155 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
 156 {
 157         return ERR_PTR(-EOPNOTSUPP);
 158 }
 159
 160 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
 161                                u64 map_flags)
 162 {
 163         struct xsk_map *m = container_of(map, struct xsk_map, map);
 164         u32 i = *(u32 *)key, fd = *(u32 *)value;
 165         struct xdp_sock *xs, *old_xs;
 166         struct socket *sock;
 167         int err;
 168
 169         if (unlikely(map_flags > BPF_EXIST))
 170                 return -EINVAL;
 171         if (unlikely(i >= m->map.max_entries))
 172                 return -E2BIG;
 173         if (unlikely(map_flags == BPF_NOEXIST))
 174                 return -EEXIST;
 175
 176         sock = sockfd_lookup(fd, &err);
 177         if (!sock)
 178                 return err;
 179
 180         if (sock->sk->sk_family != PF_XDP) {
 181                 sockfd_put(sock);
 182                 return -EOPNOTSUPP;
 183         }
 184
 185         xs = (struct xdp_sock *)sock->sk;
 186
 187         if (!xsk_is_setup_for_bpf_map(xs)) {
 188                 sockfd_put(sock);
 189                 return -EOPNOTSUPP;
 190         }
 191
 192         sock_hold(sock->sk);
 193
 194         old_xs = xchg(&m->xsk_map[i], xs);
 195         if (old_xs)
 196                 sock_put((struct sock *)old_xs);
 197
 198         sockfd_put(sock);
 199         return 0;
 200 }
 201
 202 static int xsk_map_delete_elem(struct bpf_map *map, void *key)
 203 {
 204         struct xsk_map *m = container_of(map, struct xsk_map, map);
 205         struct xdp_sock *old_xs;
 206         int k = *(u32 *)key;
 207
 208         if (k >= map->max_entries)
 209                 return -EINVAL;
 210
 211         old_xs = xchg(&m->xsk_map[k], NULL);
 212         if (old_xs)
 213                 sock_put((struct sock *)old_xs);
 214
 215         return 0;
 216 }
 217
 218 const struct bpf_map_ops xsk_map_ops = {
 219         .map_alloc = xsk_map_alloc,
 220         .map_free = xsk_map_free,
 221         .map_get_next_key = xsk_map_get_next_key,
 222         .map_lookup_elem = xsk_map_lookup_elem,
 223         .map_update_elem = xsk_map_update_elem,
 224         .map_delete_elem = xsk_map_delete_elem,
 225         .map_check_btf = map_check_no_btf,
 226 };