// 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> int xsk_map_inc(struct xsk_map *map) { bpf_map_inc(&map->map); return 0; } void xsk_map_put(struct xsk_map *map) { bpf_map_put(&map->map); } static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map, struct xdp_sock **map_entry) { struct xsk_map_node *node; int err; node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN); if (!node) return ERR_PTR(-ENOMEM); err = xsk_map_inc(map); if (err) { kfree(node); return ERR_PTR(err); } node->map = map; node->map_entry = map_entry; return node; } static void xsk_map_node_free(struct xsk_map_node *node) { xsk_map_put(node->map); kfree(node); } static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) { spin_lock_bh(&xs->map_list_lock); list_add_tail(&node->node, &xs->map_list); spin_unlock_bh(&xs->map_list_lock); } static void xsk_map_sock_delete(struct xdp_sock *xs, struct xdp_sock **map_entry) { struct xsk_map_node *n, *tmp; spin_lock_bh(&xs->map_list_lock); list_for_each_entry_safe(n, tmp, &xs->map_list, node) { if (map_entry == n->map_entry) { list_del(&n->node); xsk_map_node_free(n); } } spin_unlock_bh(&xs->map_list_lock); } static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) { struct bpf_map_memory mem; int err, numa_node; struct xsk_map *m; u64 size; 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); numa_node = bpf_map_attr_numa_node(attr); size = struct_size(m, xsk_map, attr->max_entries); err = bpf_map_charge_init(&mem, size); if (err < 0) return ERR_PTR(err); m = bpf_map_area_alloc(size, numa_node); if (!m) { bpf_map_charge_finish(&mem); return ERR_PTR(-ENOMEM); } bpf_map_init_from_attr(&m->map, attr); bpf_map_charge_move(&m->map.memory, &mem); spin_lock_init(&m->lock); return &m->map; } static void xsk_map_free(struct bpf_map *map) { struct xsk_map *m = container_of(map, struct xsk_map, map); bpf_clear_redirect_map(map); synchronize_net(); bpf_map_area_free(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; } static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) { const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; struct bpf_insn *insn = insn_buf; *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0); *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); *insn++ = BPF_MOV64_IMM(ret, 0); return insn - insn_buf; } static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) { WARN_ON_ONCE(!rcu_read_lock_held()); return __xsk_map_lookup_elem(map, *(u32 *)key); } static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) { return ERR_PTR(-EOPNOTSUPP); } 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); struct xdp_sock *xs, *old_xs, **map_entry; u32 i = *(u32 *)key, fd = *(u32 *)value; struct xsk_map_node *node; struct socket *sock; int err; if (unlikely(map_flags > BPF_EXIST)) return -EINVAL; if (unlikely(i >= m->map.max_entries)) return -E2BIG; 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; } map_entry = &m->xsk_map[i]; node = xsk_map_node_alloc(m, map_entry); if (IS_ERR(node)) { sockfd_put(sock); return PTR_ERR(node); } spin_lock_bh(&m->lock); old_xs = READ_ONCE(*map_entry); if (old_xs == xs) { err = 0; goto out; } else if (old_xs && map_flags == BPF_NOEXIST) { err = -EEXIST; goto out; } else if (!old_xs && map_flags == BPF_EXIST) { err = -ENOENT; goto out; } xsk_map_sock_add(xs, node); WRITE_ONCE(*map_entry, xs); if (old_xs) xsk_map_sock_delete(old_xs, map_entry); spin_unlock_bh(&m->lock); sockfd_put(sock); return 0; out: spin_unlock_bh(&m->lock); sockfd_put(sock); xsk_map_node_free(node); return err; } 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, **map_entry; int k = *(u32 *)key; if (k >= map->max_entries) return -EINVAL; spin_lock_bh(&m->lock); map_entry = &m->xsk_map[k]; old_xs = xchg(map_entry, NULL); if (old_xs) xsk_map_sock_delete(old_xs, map_entry); spin_unlock_bh(&m->lock); return 0; } void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, struct xdp_sock **map_entry) { spin_lock_bh(&map->lock); if (READ_ONCE(*map_entry) == xs) { WRITE_ONCE(*map_entry, NULL); xsk_map_sock_delete(xs, map_entry); } spin_unlock_bh(&map->lock); } 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_gen_lookup = xsk_map_gen_lookup, .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only, .map_update_elem = xsk_map_update_elem, .map_delete_elem = xsk_map_delete_elem, .map_check_btf = map_check_no_btf, };