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1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
3
4 #include <linux/skmsg.h>
5 #include <linux/filter.h>
6 #include <linux/bpf.h>
7 #include <linux/init.h>
8 #include <linux/wait.h>
9
10 #include <net/inet_common.h>
11 #include <net/tls.h>
12
13 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
14 struct msghdr *msg, int len, int flags)
15 {
16 struct iov_iter *iter = &msg->msg_iter;
17 int peek = flags & MSG_PEEK;
18 int i, ret, copied = 0;
19 struct sk_msg *msg_rx;
20
21 msg_rx = list_first_entry_or_null(&psock->ingress_msg,
22 struct sk_msg, list);
23
24 while (copied != len) {
25 struct scatterlist *sge;
26
27 if (unlikely(!msg_rx))
28 break;
29
30 i = msg_rx->sg.start;
31 do {
32 struct page *page;
33 int copy;
34
35 sge = sk_msg_elem(msg_rx, i);
36 copy = sge->length;
37 page = sg_page(sge);
38 if (copied + copy > len)
39 copy = len - copied;
40 ret = copy_page_to_iter(page, sge->offset, copy, iter);
41 if (ret != copy) {
42 msg_rx->sg.start = i;
43 return -EFAULT;
44 }
45
46 copied += copy;
47 if (likely(!peek)) {
48 sge->offset += copy;
49 sge->length -= copy;
50 sk_mem_uncharge(sk, copy);
51 msg_rx->sg.size -= copy;
52
53 if (!sge->length) {
54 sk_msg_iter_var_next(i);
55 if (!msg_rx->skb)
56 put_page(page);
57 }
58 } else {
59 sk_msg_iter_var_next(i);
60 }
61
62 if (copied == len)
63 break;
64 } while (i != msg_rx->sg.end);
65
66 if (unlikely(peek)) {
67 msg_rx = list_next_entry(msg_rx, list);
68 continue;
69 }
70
71 msg_rx->sg.start = i;
72 if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) {
73 list_del(&msg_rx->list);
74 if (msg_rx->skb)
75 consume_skb(msg_rx->skb);
76 kfree(msg_rx);
77 }
78 msg_rx = list_first_entry_or_null(&psock->ingress_msg,
79 struct sk_msg, list);
80 }
81
82 return copied;
83 }
84 EXPORT_SYMBOL_GPL(__tcp_bpf_recvmsg);
85
86 static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
87 struct sk_msg *msg, u32 apply_bytes, int flags)
88 {
89 bool apply = apply_bytes;
90 struct scatterlist *sge;
91 u32 size, copied = 0;
92 struct sk_msg *tmp;
93 int i, ret = 0;
94
95 tmp = kzalloc(sizeof(*tmp), __GFP_NOWARN | GFP_KERNEL);
96 if (unlikely(!tmp))
97 return -ENOMEM;
98
99 lock_sock(sk);
100 tmp->sg.start = msg->sg.start;
101 i = msg->sg.start;
102 do {
103 sge = sk_msg_elem(msg, i);
104 size = (apply && apply_bytes < sge->length) ?
105 apply_bytes : sge->length;
106 if (!sk_wmem_schedule(sk, size)) {
107 if (!copied)
108 ret = -ENOMEM;
109 break;
110 }
111
112 sk_mem_charge(sk, size);
113 sk_msg_xfer(tmp, msg, i, size);
114 copied += size;
115 if (sge->length)
116 get_page(sk_msg_page(tmp, i));
117 sk_msg_iter_var_next(i);
118 tmp->sg.end = i;
119 if (apply) {
120 apply_bytes -= size;
121 if (!apply_bytes)
122 break;
123 }
124 } while (i != msg->sg.end);
125
126 if (!ret) {
127 msg->sg.start = i;
128 msg->sg.size -= apply_bytes;
129 sk_psock_queue_msg(psock, tmp);
130 sk_psock_data_ready(sk, psock);
131 } else {
132 sk_msg_free(sk, tmp);
133 kfree(tmp);
134 }
135
136 release_sock(sk);
137 return ret;
138 }
139
140 static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
141 int flags, bool uncharge)
142 {
143 bool apply = apply_bytes;
144 struct scatterlist *sge;
145 struct page *page;
146 int size, ret = 0;
147 u32 off;
148
149 while (1) {
150 bool has_tx_ulp;
151
152 sge = sk_msg_elem(msg, msg->sg.start);
153 size = (apply && apply_bytes < sge->length) ?
154 apply_bytes : sge->length;
155 off = sge->offset;
156 page = sg_page(sge);
157
158 tcp_rate_check_app_limited(sk);
159 retry:
160 has_tx_ulp = tls_sw_has_ctx_tx(sk);
161 if (has_tx_ulp) {
162 flags |= MSG_SENDPAGE_NOPOLICY;
163 ret = kernel_sendpage_locked(sk,
164 page, off, size, flags);
165 } else {
166 ret = do_tcp_sendpages(sk, page, off, size, flags);
167 }
168
169 if (ret <= 0)
170 return ret;
171 if (apply)
172 apply_bytes -= ret;
173 msg->sg.size -= ret;
174 sge->offset += ret;
175 sge->length -= ret;
176 if (uncharge)
177 sk_mem_uncharge(sk, ret);
178 if (ret != size) {
179 size -= ret;
180 off += ret;
181 goto retry;
182 }
183 if (!sge->length) {
184 put_page(page);
185 sk_msg_iter_next(msg, start);
186 sg_init_table(sge, 1);
187 if (msg->sg.start == msg->sg.end)
188 break;
189 }
190 if (apply && !apply_bytes)
191 break;
192 }
193
194 return 0;
195 }
196
197 static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
198 u32 apply_bytes, int flags, bool uncharge)
199 {
200 int ret;
201
202 lock_sock(sk);
203 ret = tcp_bpf_push(sk, msg, apply_bytes, flags, uncharge);
204 release_sock(sk);
205 return ret;
206 }
207
208 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
209 u32 bytes, int flags)
210 {
211 bool ingress = sk_msg_to_ingress(msg);
212 struct sk_psock *psock = sk_psock_get(sk);
213 int ret;
214
215 if (unlikely(!psock)) {
216 sk_msg_free(sk, msg);
217 return 0;
218 }
219 ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes, flags) :
220 tcp_bpf_push_locked(sk, msg, bytes, flags, false);
221 sk_psock_put(sk, psock);
222 return ret;
223 }
224 EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
225
226 #ifdef CONFIG_BPF_STREAM_PARSER
227 static bool tcp_bpf_stream_read(const struct sock *sk)
228 {
229 struct sk_psock *psock;
230 bool empty = true;
231
232 rcu_read_lock();
233 psock = sk_psock(sk);
234 if (likely(psock))
235 empty = list_empty(&psock->ingress_msg);
236 rcu_read_unlock();
237 return !empty;
238 }
239
240 static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock,
241 int flags, long timeo, int *err)
242 {
243 DEFINE_WAIT_FUNC(wait, woken_wake_function);
244 int ret = 0;
245
246 if (!timeo)
247 return ret;
248
249 add_wait_queue(sk_sleep(sk), &wait);
250 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
251 ret = sk_wait_event(sk, &timeo,
252 !list_empty(&psock->ingress_msg) ||
253 !skb_queue_empty(&sk->sk_receive_queue), &wait);
254 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
255 remove_wait_queue(sk_sleep(sk), &wait);
256 return ret;
257 }
258
259 static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
260 int nonblock, int flags, int *addr_len)
261 {
262 struct sk_psock *psock;
263 int copied, ret;
264
265 psock = sk_psock_get(sk);
266 if (unlikely(!psock))
267 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
268 if (unlikely(flags & MSG_ERRQUEUE))
269 return inet_recv_error(sk, msg, len, addr_len);
270 if (!skb_queue_empty(&sk->sk_receive_queue) &&
271 sk_psock_queue_empty(psock))
272 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
273 lock_sock(sk);
274 msg_bytes_ready:
275 copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
276 if (!copied) {
277 int data, err = 0;
278 long timeo;
279
280 timeo = sock_rcvtimeo(sk, nonblock);
281 data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err);
282 if (data) {
283 if (!sk_psock_queue_empty(psock))
284 goto msg_bytes_ready;
285 release_sock(sk);
286 sk_psock_put(sk, psock);
287 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
288 }
289 if (err) {
290 ret = err;
291 goto out;
292 }
293 copied = -EAGAIN;
294 }
295 ret = copied;
296 out:
297 release_sock(sk);
298 sk_psock_put(sk, psock);
299 return ret;
300 }
301
302 static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
303 struct sk_msg *msg, int *copied, int flags)
304 {
305 bool cork = false, enospc = sk_msg_full(msg);
306 struct sock *sk_redir;
307 u32 tosend, delta = 0;
308 int ret;
309
310 more_data:
311 if (psock->eval == __SK_NONE) {
312 /* Track delta in msg size to add/subtract it on SK_DROP from
313 * returned to user copied size. This ensures user doesn't
314 * get a positive return code with msg_cut_data and SK_DROP
315 * verdict.
316 */
317 delta = msg->sg.size;
318 psock->eval = sk_psock_msg_verdict(sk, psock, msg);
319 delta -= msg->sg.size;
320 }
321
322 if (msg->cork_bytes &&
323 msg->cork_bytes > msg->sg.size && !enospc) {
324 psock->cork_bytes = msg->cork_bytes - msg->sg.size;
325 if (!psock->cork) {
326 psock->cork = kzalloc(sizeof(*psock->cork),
327 GFP_ATOMIC | __GFP_NOWARN);
328 if (!psock->cork)
329 return -ENOMEM;
330 }
331 memcpy(psock->cork, msg, sizeof(*msg));
332 return 0;
333 }
334
335 tosend = msg->sg.size;
336 if (psock->apply_bytes && psock->apply_bytes < tosend)
337 tosend = psock->apply_bytes;
338
339 switch (psock->eval) {
340 case __SK_PASS:
341 ret = tcp_bpf_push(sk, msg, tosend, flags, true);
342 if (unlikely(ret)) {
343 *copied -= sk_msg_free(sk, msg);
344 break;
345 }
346 sk_msg_apply_bytes(psock, tosend);
347 break;
348 case __SK_REDIRECT:
349 sk_redir = psock->sk_redir;
350 sk_msg_apply_bytes(psock, tosend);
351 if (psock->cork) {
352 cork = true;
353 psock->cork = NULL;
354 }
355 sk_msg_return(sk, msg, tosend);
356 release_sock(sk);
357 ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags);
358 lock_sock(sk);
359 if (unlikely(ret < 0)) {
360 int free = sk_msg_free_nocharge(sk, msg);
361
362 if (!cork)
363 *copied -= free;
364 }
365 if (cork) {
366 sk_msg_free(sk, msg);
367 kfree(msg);
368 msg = NULL;
369 ret = 0;
370 }
371 break;
372 case __SK_DROP:
373 default:
374 sk_msg_free_partial(sk, msg, tosend);
375 sk_msg_apply_bytes(psock, tosend);
376 *copied -= (tosend + delta);
377 return -EACCES;
378 }
379
380 if (likely(!ret)) {
381 if (!psock->apply_bytes) {
382 psock->eval = __SK_NONE;
383 if (psock->sk_redir) {
384 sock_put(psock->sk_redir);
385 psock->sk_redir = NULL;
386 }
387 }
388 if (msg &&
389 msg->sg.data[msg->sg.start].page_link &&
390 msg->sg.data[msg->sg.start].length)
391 goto more_data;
392 }
393 return ret;
394 }
395
396 static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
397 {
398 struct sk_msg tmp, *msg_tx = NULL;
399 int copied = 0, err = 0;
400 struct sk_psock *psock;
401 long timeo;
402 int flags;
403
404 /* Don't let internal do_tcp_sendpages() flags through */
405 flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
406 flags |= MSG_NO_SHARED_FRAGS;
407
408 psock = sk_psock_get(sk);
409 if (unlikely(!psock))
410 return tcp_sendmsg(sk, msg, size);
411
412 lock_sock(sk);
413 timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
414 while (msg_data_left(msg)) {
415 bool enospc = false;
416 u32 copy, osize;
417
418 if (sk->sk_err) {
419 err = -sk->sk_err;
420 goto out_err;
421 }
422
423 copy = msg_data_left(msg);
424 if (!sk_stream_memory_free(sk))
425 goto wait_for_sndbuf;
426 if (psock->cork) {
427 msg_tx = psock->cork;
428 } else {
429 msg_tx = &tmp;
430 sk_msg_init(msg_tx);
431 }
432
433 osize = msg_tx->sg.size;
434 err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
435 if (err) {
436 if (err != -ENOSPC)
437 goto wait_for_memory;
438 enospc = true;
439 copy = msg_tx->sg.size - osize;
440 }
441
442 err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx,
443 copy);
444 if (err < 0) {
445 sk_msg_trim(sk, msg_tx, osize);
446 goto out_err;
447 }
448
449 copied += copy;
450 if (psock->cork_bytes) {
451 if (size > psock->cork_bytes)
452 psock->cork_bytes = 0;
453 else
454 psock->cork_bytes -= size;
455 if (psock->cork_bytes && !enospc)
456 goto out_err;
457 /* All cork bytes are accounted, rerun the prog. */
458 psock->eval = __SK_NONE;
459 psock->cork_bytes = 0;
460 }
461
462 err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags);
463 if (unlikely(err < 0))
464 goto out_err;
465 continue;
466 wait_for_sndbuf:
467 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
468 wait_for_memory:
469 err = sk_stream_wait_memory(sk, &timeo);
470 if (err) {
471 if (msg_tx && msg_tx != psock->cork)
472 sk_msg_free(sk, msg_tx);
473 goto out_err;
474 }
475 }
476 out_err:
477 if (err < 0)
478 err = sk_stream_error(sk, msg->msg_flags, err);
479 release_sock(sk);
480 sk_psock_put(sk, psock);
481 return copied ? copied : err;
482 }
483
484 static int tcp_bpf_sendpage(struct sock *sk, struct page *page, int offset,
485 size_t size, int flags)
486 {
487 struct sk_msg tmp, *msg = NULL;
488 int err = 0, copied = 0;
489 struct sk_psock *psock;
490 bool enospc = false;
491
492 psock = sk_psock_get(sk);
493 if (unlikely(!psock))
494 return tcp_sendpage(sk, page, offset, size, flags);
495
496 lock_sock(sk);
497 if (psock->cork) {
498 msg = psock->cork;
499 } else {
500 msg = &tmp;
501 sk_msg_init(msg);
502 }
503
504 /* Catch case where ring is full and sendpage is stalled. */
505 if (unlikely(sk_msg_full(msg)))
506 goto out_err;
507
508 sk_msg_page_add(msg, page, size, offset);
509 sk_mem_charge(sk, size);
510 copied = size;
511 if (sk_msg_full(msg))
512 enospc = true;
513 if (psock->cork_bytes) {
514 if (size > psock->cork_bytes)
515 psock->cork_bytes = 0;
516 else
517 psock->cork_bytes -= size;
518 if (psock->cork_bytes && !enospc)
519 goto out_err;
520 /* All cork bytes are accounted, rerun the prog. */
521 psock->eval = __SK_NONE;
522 psock->cork_bytes = 0;
523 }
524
525 err = tcp_bpf_send_verdict(sk, psock, msg, &copied, flags);
526 out_err:
527 release_sock(sk);
528 sk_psock_put(sk, psock);
529 return copied ? copied : err;
530 }
531
532 enum {
533 TCP_BPF_IPV4,
534 TCP_BPF_IPV6,
535 TCP_BPF_NUM_PROTS,
536 };
537
538 enum {
539 TCP_BPF_BASE,
540 TCP_BPF_TX,
541 TCP_BPF_NUM_CFGS,
542 };
543
544 static struct proto *tcpv6_prot_saved __read_mostly;
545 static DEFINE_SPINLOCK(tcpv6_prot_lock);
546 static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
547
548 static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
549 struct proto *base)
550 {
551 prot[TCP_BPF_BASE] = *base;
552 prot[TCP_BPF_BASE].unhash = sock_map_unhash;
553 prot[TCP_BPF_BASE].close = sock_map_close;
554 prot[TCP_BPF_BASE].recvmsg = tcp_bpf_recvmsg;
555 prot[TCP_BPF_BASE].stream_memory_read = tcp_bpf_stream_read;
556
557 prot[TCP_BPF_TX] = prot[TCP_BPF_BASE];
558 prot[TCP_BPF_TX].sendmsg = tcp_bpf_sendmsg;
559 prot[TCP_BPF_TX].sendpage = tcp_bpf_sendpage;
560 }
561
562 static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
563 {
564 if (sk->sk_family == AF_INET6 &&
565 unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
566 spin_lock_bh(&tcpv6_prot_lock);
567 if (likely(ops != tcpv6_prot_saved)) {
568 tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
569 smp_store_release(&tcpv6_prot_saved, ops);
570 }
571 spin_unlock_bh(&tcpv6_prot_lock);
572 }
573 }
574
575 static int __init tcp_bpf_v4_build_proto(void)
576 {
577 tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
578 return 0;
579 }
580 core_initcall(tcp_bpf_v4_build_proto);
581
582 static int tcp_bpf_assert_proto_ops(struct proto *ops)
583 {
584 /* In order to avoid retpoline, we make assumptions when we call
585 * into ops if e.g. a psock is not present. Make sure they are
586 * indeed valid assumptions.
587 */
588 return ops->recvmsg == tcp_recvmsg &&
589 ops->sendmsg == tcp_sendmsg &&
590 ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
591 }
592
593 struct proto *tcp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
594 {
595 int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
596 int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE;
597
598 if (!psock->sk_proto) {
599 struct proto *ops = READ_ONCE(sk->sk_prot);
600
601 if (tcp_bpf_assert_proto_ops(ops))
602 return ERR_PTR(-EINVAL);
603
604 tcp_bpf_check_v6_needs_rebuild(sk, ops);
605 }
606
607 return &tcp_bpf_prots[family][config];
608 }
609
610 /* If a child got cloned from a listening socket that had tcp_bpf
611 * protocol callbacks installed, we need to restore the callbacks to
612 * the default ones because the child does not inherit the psock state
613 * that tcp_bpf callbacks expect.
614 */
615 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
616 {
617 int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
618 struct proto *prot = newsk->sk_prot;
619
620 if (prot == &tcp_bpf_prots[family][TCP_BPF_BASE])
621 newsk->sk_prot = sk->sk_prot_creator;
622 }
623 #endif /* CONFIG_BPF_STREAM_PARSER */