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
 14int xsk_map_inc(struct xsk_map *map)
 15{
 16	bpf_map_inc(&map->map);
 17	return 0;
 18}
 19
 20void xsk_map_put(struct xsk_map *map)
 21{
 22	bpf_map_put(&map->map);
 23}
 24
 25static 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
 46static void xsk_map_node_free(struct xsk_map_node *node)
 47{
 48	xsk_map_put(node->map);
 49	kfree(node);
 50}
 51
 52static 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
 59static 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
 74static 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
109static 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
118static 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
135static 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
151static 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
157static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
158{
159	return ERR_PTR(-EOPNOTSUPP);
160}
161
162static 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
220out:
221	spin_unlock_bh(&m->lock);
222	sockfd_put(sock);
223	xsk_map_node_free(node);
224	return err;
225}
226
227static 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
246void 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
257static int xsk_map_btf_id;
258const 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};