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5#include <linux/bpf.h>
6#include <linux/err.h>
7#include <linux/sock_diag.h>
8#include <net/sock_reuseport.h>
9
10struct reuseport_array {
11 struct bpf_map map;
12 struct sock __rcu *ptrs[];
13};
14
15static struct reuseport_array *reuseport_array(struct bpf_map *map)
16{
17 return (struct reuseport_array *)map;
18}
19
20
21void bpf_sk_reuseport_detach(struct sock *sk)
22{
23 uintptr_t sk_user_data;
24
25 write_lock_bh(&sk->sk_callback_lock);
26 sk_user_data = (uintptr_t)sk->sk_user_data;
27 if (sk_user_data & SK_USER_DATA_BPF) {
28 struct sock __rcu **socks;
29
30 socks = (void *)(sk_user_data & SK_USER_DATA_PTRMASK);
31 WRITE_ONCE(sk->sk_user_data, NULL);
32
33
34
35
36
37
38 RCU_INIT_POINTER(*socks, NULL);
39 }
40 write_unlock_bh(&sk->sk_callback_lock);
41}
42
43static int reuseport_array_alloc_check(union bpf_attr *attr)
44{
45 if (attr->value_size != sizeof(u32) &&
46 attr->value_size != sizeof(u64))
47 return -EINVAL;
48
49 return array_map_alloc_check(attr);
50}
51
52static void *reuseport_array_lookup_elem(struct bpf_map *map, void *key)
53{
54 struct reuseport_array *array = reuseport_array(map);
55 u32 index = *(u32 *)key;
56
57 if (unlikely(index >= array->map.max_entries))
58 return NULL;
59
60 return rcu_dereference(array->ptrs[index]);
61}
62
63
64static int reuseport_array_delete_elem(struct bpf_map *map, void *key)
65{
66 struct reuseport_array *array = reuseport_array(map);
67 u32 index = *(u32 *)key;
68 struct sock *sk;
69 int err;
70
71 if (index >= map->max_entries)
72 return -E2BIG;
73
74 if (!rcu_access_pointer(array->ptrs[index]))
75 return -ENOENT;
76
77 spin_lock_bh(&reuseport_lock);
78
79 sk = rcu_dereference_protected(array->ptrs[index],
80 lockdep_is_held(&reuseport_lock));
81 if (sk) {
82 write_lock_bh(&sk->sk_callback_lock);
83 WRITE_ONCE(sk->sk_user_data, NULL);
84 RCU_INIT_POINTER(array->ptrs[index], NULL);
85 write_unlock_bh(&sk->sk_callback_lock);
86 err = 0;
87 } else {
88 err = -ENOENT;
89 }
90
91 spin_unlock_bh(&reuseport_lock);
92
93 return err;
94}
95
96static void reuseport_array_free(struct bpf_map *map)
97{
98 struct reuseport_array *array = reuseport_array(map);
99 struct sock *sk;
100 u32 i;
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126
127 rcu_read_lock();
128 for (i = 0; i < map->max_entries; i++) {
129 sk = rcu_dereference(array->ptrs[i]);
130 if (sk) {
131 write_lock_bh(&sk->sk_callback_lock);
132
133
134
135
136
137 sk->sk_user_data = NULL;
138 write_unlock_bh(&sk->sk_callback_lock);
139 RCU_INIT_POINTER(array->ptrs[i], NULL);
140 }
141 }
142 rcu_read_unlock();
143
144
145
146
147
148 bpf_map_area_free(array);
149}
150
151static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr)
152{
153 int err, numa_node = bpf_map_attr_numa_node(attr);
154 struct reuseport_array *array;
155 struct bpf_map_memory mem;
156 u64 array_size;
157
158 if (!bpf_capable())
159 return ERR_PTR(-EPERM);
160
161 array_size = sizeof(*array);
162 array_size += (u64)attr->max_entries * sizeof(struct sock *);
163
164 err = bpf_map_charge_init(&mem, array_size);
165 if (err)
166 return ERR_PTR(err);
167
168
169 array = bpf_map_area_alloc(array_size, numa_node);
170 if (!array) {
171 bpf_map_charge_finish(&mem);
172 return ERR_PTR(-ENOMEM);
173 }
174
175
176 bpf_map_init_from_attr(&array->map, attr);
177 bpf_map_charge_move(&array->map.memory, &mem);
178
179 return &array->map;
180}
181
182int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key,
183 void *value)
184{
185 struct sock *sk;
186 int err;
187
188 if (map->value_size != sizeof(u64))
189 return -ENOSPC;
190
191 rcu_read_lock();
192 sk = reuseport_array_lookup_elem(map, key);
193 if (sk) {
194 *(u64 *)value = sock_gen_cookie(sk);
195 err = 0;
196 } else {
197 err = -ENOENT;
198 }
199 rcu_read_unlock();
200
201 return err;
202}
203
204static int
205reuseport_array_update_check(const struct reuseport_array *array,
206 const struct sock *nsk,
207 const struct sock *osk,
208 const struct sock_reuseport *nsk_reuse,
209 u32 map_flags)
210{
211 if (osk && map_flags == BPF_NOEXIST)
212 return -EEXIST;
213
214 if (!osk && map_flags == BPF_EXIST)
215 return -ENOENT;
216
217 if (nsk->sk_protocol != IPPROTO_UDP && nsk->sk_protocol != IPPROTO_TCP)
218 return -ENOTSUPP;
219
220 if (nsk->sk_family != AF_INET && nsk->sk_family != AF_INET6)
221 return -ENOTSUPP;
222
223 if (nsk->sk_type != SOCK_STREAM && nsk->sk_type != SOCK_DGRAM)
224 return -ENOTSUPP;
225
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232
233
234 if (!sock_flag(nsk, SOCK_RCU_FREE) || !sk_hashed(nsk) || !nsk_reuse)
235 return -EINVAL;
236
237
238 if (READ_ONCE(nsk->sk_user_data))
239 return -EBUSY;
240
241 return 0;
242}
243
244
245
246
247
248
249int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key,
250 void *value, u64 map_flags)
251{
252 struct reuseport_array *array = reuseport_array(map);
253 struct sock *free_osk = NULL, *osk, *nsk;
254 struct sock_reuseport *reuse;
255 u32 index = *(u32 *)key;
256 uintptr_t sk_user_data;
257 struct socket *socket;
258 int err, fd;
259
260 if (map_flags > BPF_EXIST)
261 return -EINVAL;
262
263 if (index >= map->max_entries)
264 return -E2BIG;
265
266 if (map->value_size == sizeof(u64)) {
267 u64 fd64 = *(u64 *)value;
268
269 if (fd64 > S32_MAX)
270 return -EINVAL;
271 fd = fd64;
272 } else {
273 fd = *(int *)value;
274 }
275
276 socket = sockfd_lookup(fd, &err);
277 if (!socket)
278 return err;
279
280 nsk = socket->sk;
281 if (!nsk) {
282 err = -EINVAL;
283 goto put_file;
284 }
285
286
287 err = reuseport_array_update_check(array, nsk,
288 rcu_access_pointer(array->ptrs[index]),
289 rcu_access_pointer(nsk->sk_reuseport_cb),
290 map_flags);
291 if (err)
292 goto put_file;
293
294 spin_lock_bh(&reuseport_lock);
295
296
297
298
299
300 write_lock_bh(&nsk->sk_callback_lock);
301
302 osk = rcu_dereference_protected(array->ptrs[index],
303 lockdep_is_held(&reuseport_lock));
304 reuse = rcu_dereference_protected(nsk->sk_reuseport_cb,
305 lockdep_is_held(&reuseport_lock));
306 err = reuseport_array_update_check(array, nsk, osk, reuse, map_flags);
307 if (err)
308 goto put_file_unlock;
309
310 sk_user_data = (uintptr_t)&array->ptrs[index] | SK_USER_DATA_NOCOPY |
311 SK_USER_DATA_BPF;
312 WRITE_ONCE(nsk->sk_user_data, (void *)sk_user_data);
313 rcu_assign_pointer(array->ptrs[index], nsk);
314 free_osk = osk;
315 err = 0;
316
317put_file_unlock:
318 write_unlock_bh(&nsk->sk_callback_lock);
319
320 if (free_osk) {
321 write_lock_bh(&free_osk->sk_callback_lock);
322 WRITE_ONCE(free_osk->sk_user_data, NULL);
323 write_unlock_bh(&free_osk->sk_callback_lock);
324 }
325
326 spin_unlock_bh(&reuseport_lock);
327put_file:
328 fput(socket->file);
329 return err;
330}
331
332
333static int reuseport_array_get_next_key(struct bpf_map *map, void *key,
334 void *next_key)
335{
336 struct reuseport_array *array = reuseport_array(map);
337 u32 index = key ? *(u32 *)key : U32_MAX;
338 u32 *next = (u32 *)next_key;
339
340 if (index >= array->map.max_entries) {
341 *next = 0;
342 return 0;
343 }
344
345 if (index == array->map.max_entries - 1)
346 return -ENOENT;
347
348 *next = index + 1;
349 return 0;
350}
351
352static int reuseport_array_map_btf_id;
353const struct bpf_map_ops reuseport_array_ops = {
354 .map_alloc_check = reuseport_array_alloc_check,
355 .map_alloc = reuseport_array_alloc,
356 .map_free = reuseport_array_free,
357 .map_lookup_elem = reuseport_array_lookup_elem,
358 .map_get_next_key = reuseport_array_get_next_key,
359 .map_delete_elem = reuseport_array_delete_elem,
360 .map_btf_name = "reuseport_array",
361 .map_btf_id = &reuseport_array_map_btf_id,
362};
363