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 spinlock_t lock; /* Synchronize map updates */
17 };
18
xsk_map_inc(struct xsk_map * map)19 int xsk_map_inc(struct xsk_map *map)
20 {
21 struct bpf_map *m = &map->map;
22
23 m = bpf_map_inc(m, false);
24 return PTR_ERR_OR_ZERO(m);
25 }
26
xsk_map_put(struct xsk_map * map)27 void xsk_map_put(struct xsk_map *map)
28 {
29 bpf_map_put(&map->map);
30 }
31
xsk_map_node_alloc(struct xsk_map * map,struct xdp_sock ** map_entry)32 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
33 struct xdp_sock **map_entry)
34 {
35 struct xsk_map_node *node;
36 int err;
37
38 node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN);
39 if (!node)
40 return ERR_PTR(-ENOMEM);
41
42 err = xsk_map_inc(map);
43 if (err) {
44 kfree(node);
45 return ERR_PTR(err);
46 }
47
48 node->map = map;
49 node->map_entry = map_entry;
50 return node;
51 }
52
xsk_map_node_free(struct xsk_map_node * node)53 static void xsk_map_node_free(struct xsk_map_node *node)
54 {
55 xsk_map_put(node->map);
56 kfree(node);
57 }
58
xsk_map_sock_add(struct xdp_sock * xs,struct xsk_map_node * node)59 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
60 {
61 spin_lock_bh(&xs->map_list_lock);
62 list_add_tail(&node->node, &xs->map_list);
63 spin_unlock_bh(&xs->map_list_lock);
64 }
65
xsk_map_sock_delete(struct xdp_sock * xs,struct xdp_sock ** map_entry)66 static void xsk_map_sock_delete(struct xdp_sock *xs,
67 struct xdp_sock **map_entry)
68 {
69 struct xsk_map_node *n, *tmp;
70
71 spin_lock_bh(&xs->map_list_lock);
72 list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
73 if (map_entry == n->map_entry) {
74 list_del(&n->node);
75 xsk_map_node_free(n);
76 }
77 }
78 spin_unlock_bh(&xs->map_list_lock);
79 }
80
xsk_map_alloc(union bpf_attr * attr)81 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
82 {
83 struct xsk_map *m;
84 int cpu, err;
85 u64 cost;
86
87 if (!capable(CAP_NET_ADMIN))
88 return ERR_PTR(-EPERM);
89
90 if (attr->max_entries == 0 || attr->key_size != 4 ||
91 attr->value_size != 4 ||
92 attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
93 return ERR_PTR(-EINVAL);
94
95 m = kzalloc(sizeof(*m), GFP_USER);
96 if (!m)
97 return ERR_PTR(-ENOMEM);
98
99 bpf_map_init_from_attr(&m->map, attr);
100 spin_lock_init(&m->lock);
101
102 cost = (u64)m->map.max_entries * sizeof(struct xdp_sock *);
103 cost += sizeof(struct list_head) * num_possible_cpus();
104
105 /* Notice returns -EPERM on if map size is larger than memlock limit */
106 err = bpf_map_charge_init(&m->map.memory, cost);
107 if (err)
108 goto free_m;
109
110 err = -ENOMEM;
111
112 m->flush_list = alloc_percpu(struct list_head);
113 if (!m->flush_list)
114 goto free_charge;
115
116 for_each_possible_cpu(cpu)
117 INIT_LIST_HEAD(per_cpu_ptr(m->flush_list, cpu));
118
119 m->xsk_map = bpf_map_area_alloc(m->map.max_entries *
120 sizeof(struct xdp_sock *),
121 m->map.numa_node);
122 if (!m->xsk_map)
123 goto free_percpu;
124 return &m->map;
125
126 free_percpu:
127 free_percpu(m->flush_list);
128 free_charge:
129 bpf_map_charge_finish(&m->map.memory);
130 free_m:
131 kfree(m);
132 return ERR_PTR(err);
133 }
134
xsk_map_free(struct bpf_map * map)135 static void xsk_map_free(struct bpf_map *map)
136 {
137 struct xsk_map *m = container_of(map, struct xsk_map, map);
138
139 bpf_clear_redirect_map(map);
140 synchronize_net();
141 free_percpu(m->flush_list);
142 bpf_map_area_free(m->xsk_map);
143 kfree(m);
144 }
145
xsk_map_get_next_key(struct bpf_map * map,void * key,void * next_key)146 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
147 {
148 struct xsk_map *m = container_of(map, struct xsk_map, map);
149 u32 index = key ? *(u32 *)key : U32_MAX;
150 u32 *next = next_key;
151
152 if (index >= m->map.max_entries) {
153 *next = 0;
154 return 0;
155 }
156
157 if (index == m->map.max_entries - 1)
158 return -ENOENT;
159 *next = index + 1;
160 return 0;
161 }
162
__xsk_map_lookup_elem(struct bpf_map * map,u32 key)163 struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
164 {
165 struct xsk_map *m = container_of(map, struct xsk_map, map);
166 struct xdp_sock *xs;
167
168 if (key >= map->max_entries)
169 return NULL;
170
171 xs = READ_ONCE(m->xsk_map[key]);
172 return xs;
173 }
174
__xsk_map_redirect(struct bpf_map * map,struct xdp_buff * xdp,struct xdp_sock * xs)175 int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
176 struct xdp_sock *xs)
177 {
178 struct xsk_map *m = container_of(map, struct xsk_map, map);
179 struct list_head *flush_list = this_cpu_ptr(m->flush_list);
180 int err;
181
182 err = xsk_rcv(xs, xdp);
183 if (err)
184 return err;
185
186 if (!xs->flush_node.prev)
187 list_add(&xs->flush_node, flush_list);
188
189 return 0;
190 }
191
__xsk_map_flush(struct bpf_map * map)192 void __xsk_map_flush(struct bpf_map *map)
193 {
194 struct xsk_map *m = container_of(map, struct xsk_map, map);
195 struct list_head *flush_list = this_cpu_ptr(m->flush_list);
196 struct xdp_sock *xs, *tmp;
197
198 list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
199 xsk_flush(xs);
200 __list_del_clearprev(&xs->flush_node);
201 }
202 }
203
xsk_map_lookup_elem(struct bpf_map * map,void * key)204 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
205 {
206 WARN_ON_ONCE(!rcu_read_lock_held());
207 return __xsk_map_lookup_elem(map, *(u32 *)key);
208 }
209
xsk_map_lookup_elem_sys_only(struct bpf_map * map,void * key)210 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
211 {
212 return ERR_PTR(-EOPNOTSUPP);
213 }
214
xsk_map_update_elem(struct bpf_map * map,void * key,void * value,u64 map_flags)215 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
216 u64 map_flags)
217 {
218 struct xsk_map *m = container_of(map, struct xsk_map, map);
219 struct xdp_sock *xs, *old_xs, **map_entry;
220 u32 i = *(u32 *)key, fd = *(u32 *)value;
221 struct xsk_map_node *node;
222 struct socket *sock;
223 int err;
224
225 if (unlikely(map_flags > BPF_EXIST))
226 return -EINVAL;
227 if (unlikely(i >= m->map.max_entries))
228 return -E2BIG;
229
230 sock = sockfd_lookup(fd, &err);
231 if (!sock)
232 return err;
233
234 if (sock->sk->sk_family != PF_XDP) {
235 sockfd_put(sock);
236 return -EOPNOTSUPP;
237 }
238
239 xs = (struct xdp_sock *)sock->sk;
240
241 if (!xsk_is_setup_for_bpf_map(xs)) {
242 sockfd_put(sock);
243 return -EOPNOTSUPP;
244 }
245
246 map_entry = &m->xsk_map[i];
247 node = xsk_map_node_alloc(m, map_entry);
248 if (IS_ERR(node)) {
249 sockfd_put(sock);
250 return PTR_ERR(node);
251 }
252
253 spin_lock_bh(&m->lock);
254 old_xs = READ_ONCE(*map_entry);
255 if (old_xs == xs) {
256 err = 0;
257 goto out;
258 } else if (old_xs && map_flags == BPF_NOEXIST) {
259 err = -EEXIST;
260 goto out;
261 } else if (!old_xs && map_flags == BPF_EXIST) {
262 err = -ENOENT;
263 goto out;
264 }
265 xsk_map_sock_add(xs, node);
266 WRITE_ONCE(*map_entry, xs);
267 if (old_xs)
268 xsk_map_sock_delete(old_xs, map_entry);
269 spin_unlock_bh(&m->lock);
270 sockfd_put(sock);
271 return 0;
272
273 out:
274 spin_unlock_bh(&m->lock);
275 sockfd_put(sock);
276 xsk_map_node_free(node);
277 return err;
278 }
279
xsk_map_delete_elem(struct bpf_map * map,void * key)280 static int xsk_map_delete_elem(struct bpf_map *map, void *key)
281 {
282 struct xsk_map *m = container_of(map, struct xsk_map, map);
283 struct xdp_sock *old_xs, **map_entry;
284 int k = *(u32 *)key;
285
286 if (k >= map->max_entries)
287 return -EINVAL;
288
289 spin_lock_bh(&m->lock);
290 map_entry = &m->xsk_map[k];
291 old_xs = xchg(map_entry, NULL);
292 if (old_xs)
293 xsk_map_sock_delete(old_xs, map_entry);
294 spin_unlock_bh(&m->lock);
295
296 return 0;
297 }
298
xsk_map_try_sock_delete(struct xsk_map * map,struct xdp_sock * xs,struct xdp_sock ** map_entry)299 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
300 struct xdp_sock **map_entry)
301 {
302 spin_lock_bh(&map->lock);
303 if (READ_ONCE(*map_entry) == xs) {
304 WRITE_ONCE(*map_entry, NULL);
305 xsk_map_sock_delete(xs, map_entry);
306 }
307 spin_unlock_bh(&map->lock);
308 }
309
310 const struct bpf_map_ops xsk_map_ops = {
311 .map_alloc = xsk_map_alloc,
312 .map_free = xsk_map_free,
313 .map_get_next_key = xsk_map_get_next_key,
314 .map_lookup_elem = xsk_map_lookup_elem,
315 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
316 .map_update_elem = xsk_map_update_elem,
317 .map_delete_elem = xsk_map_delete_elem,
318 .map_check_btf = map_check_no_btf,
319 };
320
