net/xdp/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 #include "xsk.h"
  13
  14 int xsk_map_inc(struct xsk_map *map)
  15 {
  16         bpf_map_inc(&map->map);
  17         return 0;
  18 }
  19
  20 void xsk_map_put(struct xsk_map *map)
  21 {
  22         bpf_map_put(&map->map);
  23 }
  24
  25 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
  26                                                struct xdp_sock **map_entry)
  27 {
  28         struct xsk_map_node *node;
  29         int err;
  30
  31         node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN);
  32         if (!node)
  33                 return ERR_PTR(-ENOMEM);
  34
  35         err = xsk_map_inc(map);
  36         if (err) {
  37                 kfree(node);
  38                 return ERR_PTR(err);
  39         }
  40
  41         node->map = map;
  42         node->map_entry = map_entry;
  43         return node;
  44 }
  45
  46 static void xsk_map_node_free(struct xsk_map_node *node)
  47 {
  48         xsk_map_put(node->map);
  49         kfree(node);
  50 }
  51
  52 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
  53 {
  54         spin_lock_bh(&xs->map_list_lock);
  55         list_add_tail(&node->node, &xs->map_list);
  56         spin_unlock_bh(&xs->map_list_lock);
  57 }
  58
  59 static void xsk_map_sock_delete(struct xdp_sock *xs,
  60                                 struct xdp_sock **map_entry)
  61 {
  62         struct xsk_map_node *n, *tmp;
  63
  64         spin_lock_bh(&xs->map_list_lock);
  65         list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
  66                 if (map_entry == n->map_entry) {
  67                         list_del(&n->node);
  68                         xsk_map_node_free(n);
  69                 }
  70         }
  71         spin_unlock_bh(&xs->map_list_lock);
  72 }
  73
  74 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
  75 {
  76         struct bpf_map_memory mem;
  77         int err, numa_node;
  78         struct xsk_map *m;
  79         u64 size;
  80
  81         if (!capable(CAP_NET_ADMIN))
  82                 return ERR_PTR(-EPERM);
  83
  84         if (attr->max_entries == 0 || attr->key_size != 4 ||
  85             attr->value_size != 4 ||
  86             attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
  87                 return ERR_PTR(-EINVAL);
  88
  89         numa_node = bpf_map_attr_numa_node(attr);
  90         size = struct_size(m, xsk_map, attr->max_entries);
  91
  92         err = bpf_map_charge_init(&mem, size);
  93         if (err < 0)
  94                 return ERR_PTR(err);
  95
  96         m = bpf_map_area_alloc(size, numa_node);
  97         if (!m) {
  98                 bpf_map_charge_finish(&mem);
  99                 return ERR_PTR(-ENOMEM);
 100         }
 101
 102         bpf_map_init_from_attr(&m->map, attr);
 103         bpf_map_charge_move(&m->map.memory, &mem);
 104         spin_lock_init(&m->lock);
 105
 106         return &m->map;
 107 }
 108
 109 static void xsk_map_free(struct bpf_map *map)
 110 {
 111         struct xsk_map *m = container_of(map, struct xsk_map, map);
 112
 113         bpf_clear_redirect_map(map);
 114         synchronize_net();
 115         bpf_map_area_free(m);
 116 }
 117
 118 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 119 {
 120         struct xsk_map *m = container_of(map, struct xsk_map, map);
 121         u32 index = key ? *(u32 *)key : U32_MAX;
 122         u32 *next = next_key;
 123
 124         if (index >= m->map.max_entries) {
 125                 *next = 0;
 126                 return 0;
 127         }
 128
 129         if (index == m->map.max_entries - 1)
 130                 return -ENOENT;
 131         *next = index + 1;
 132         return 0;
 133 }
 134
 135 static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 136 {
 137         const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
 138         struct bpf_insn *insn = insn_buf;
 139
 140         *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
 141         *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
 142         *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
 143         *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
 144         *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
 145         *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
 146         *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
 147         *insn++ = BPF_MOV64_IMM(ret, 0);
 148         return insn - insn_buf;
 149 }
 150
 151 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
 152 {
 153         WARN_ON_ONCE(!rcu_read_lock_held());
 154         return __xsk_map_lookup_elem(map, *(u32 *)key);
 155 }
 156
 157 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
 158 {
 159         return ERR_PTR(-EOPNOTSUPP);
 160 }
 161
 162 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
 163                                u64 map_flags)
 164 {
 165         struct xsk_map *m = container_of(map, struct xsk_map, map);
 166         struct xdp_sock *xs, *old_xs, **map_entry;
 167         u32 i = *(u32 *)key, fd = *(u32 *)value;
 168         struct xsk_map_node *node;
 169         struct socket *sock;
 170         int err;
 171
 172         if (unlikely(map_flags > BPF_EXIST))
 173                 return -EINVAL;
 174         if (unlikely(i >= m->map.max_entries))
 175                 return -E2BIG;
 176
 177         sock = sockfd_lookup(fd, &err);
 178         if (!sock)
 179                 return err;
 180
 181         if (sock->sk->sk_family != PF_XDP) {
 182                 sockfd_put(sock);
 183                 return -EOPNOTSUPP;
 184         }
 185
 186         xs = (struct xdp_sock *)sock->sk;
 187
 188         if (!xsk_is_setup_for_bpf_map(xs)) {
 189                 sockfd_put(sock);
 190                 return -EOPNOTSUPP;
 191         }
 192
 193         map_entry = &m->xsk_map[i];
 194         node = xsk_map_node_alloc(m, map_entry);
 195         if (IS_ERR(node)) {
 196                 sockfd_put(sock);
 197                 return PTR_ERR(node);
 198         }
 199
 200         spin_lock_bh(&m->lock);
 201         old_xs = READ_ONCE(*map_entry);
 202         if (old_xs == xs) {
 203                 err = 0;
 204                 goto out;
 205         } else if (old_xs && map_flags == BPF_NOEXIST) {
 206                 err = -EEXIST;
 207                 goto out;
 208         } else if (!old_xs && map_flags == BPF_EXIST) {
 209                 err = -ENOENT;
 210                 goto out;
 211         }
 212         xsk_map_sock_add(xs, node);
 213         WRITE_ONCE(*map_entry, xs);
 214         if (old_xs)
 215                 xsk_map_sock_delete(old_xs, map_entry);
 216         spin_unlock_bh(&m->lock);
 217         sockfd_put(sock);
 218         return 0;
 219
 220 out:
 221         spin_unlock_bh(&m->lock);
 222         sockfd_put(sock);
 223         xsk_map_node_free(node);
 224         return err;
 225 }
 226
 227 static int xsk_map_delete_elem(struct bpf_map *map, void *key)
 228 {
 229         struct xsk_map *m = container_of(map, struct xsk_map, map);
 230         struct xdp_sock *old_xs, **map_entry;
 231         int k = *(u32 *)key;
 232
 233         if (k >= map->max_entries)
 234                 return -EINVAL;
 235
 236         spin_lock_bh(&m->lock);
 237         map_entry = &m->xsk_map[k];
 238         old_xs = xchg(map_entry, NULL);
 239         if (old_xs)
 240                 xsk_map_sock_delete(old_xs, map_entry);
 241         spin_unlock_bh(&m->lock);
 242
 243         return 0;
 244 }
 245
 246 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
 247                              struct xdp_sock **map_entry)
 248 {
 249         spin_lock_bh(&map->lock);
 250         if (READ_ONCE(*map_entry) == xs) {
 251                 WRITE_ONCE(*map_entry, NULL);
 252                 xsk_map_sock_delete(xs, map_entry);
 253         }
 254         spin_unlock_bh(&map->lock);
 255 }
 256
 257 static int xsk_map_btf_id;
 258 const struct bpf_map_ops xsk_map_ops = {
 259         .map_alloc = xsk_map_alloc,
 260         .map_free = xsk_map_free,
 261         .map_get_next_key = xsk_map_get_next_key,
 262         .map_lookup_elem = xsk_map_lookup_elem,
 263         .map_gen_lookup = xsk_map_gen_lookup,
 264         .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
 265         .map_update_elem = xsk_map_update_elem,
 266         .map_delete_elem = xsk_map_delete_elem,
 267         .map_check_btf = map_check_no_btf,
 268         .map_btf_name = "xsk_map",
 269         .map_btf_id = &xsk_map_btf_id,
 270 };