xref: /linux/net/ipv4/tcp_bpf.c (revision 5d7f3375cd574fc83f0cd30839b21455c0e79ae2)
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 #include <linux/util_macros.h>
10 
11 #include <net/inet_common.h>
12 #include <net/tls.h>
13 #include <asm/ioctls.h>
14 
15 void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
16 {
17 	struct tcp_sock *tcp;
18 	int copied;
19 
20 	if (!skb || !skb->len || !sk_is_tcp(sk))
21 		return;
22 
23 	if (skb_bpf_strparser(skb))
24 		return;
25 
26 	tcp = tcp_sk(sk);
27 	copied = tcp->copied_seq + skb->len;
28 	WRITE_ONCE(tcp->copied_seq, copied);
29 	tcp_rcv_space_adjust(sk);
30 	__tcp_cleanup_rbuf(sk, skb->len);
31 }
32 
33 static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
34 			   struct sk_msg *msg, u32 apply_bytes)
35 {
36 	bool apply = apply_bytes;
37 	struct scatterlist *sge;
38 	u32 size, copied = 0;
39 	struct sk_msg *tmp;
40 	int i, ret = 0;
41 
42 	tmp = kzalloc_obj(*tmp, __GFP_NOWARN | GFP_KERNEL);
43 	if (unlikely(!tmp))
44 		return -ENOMEM;
45 
46 	lock_sock(sk);
47 	tmp->sg.start = msg->sg.start;
48 	i = msg->sg.start;
49 	do {
50 		sge = sk_msg_elem(msg, i);
51 		size = (apply && apply_bytes < sge->length) ?
52 			apply_bytes : sge->length;
53 		if (!__sk_rmem_schedule(sk, size, false)) {
54 			if (!copied)
55 				ret = -ENOMEM;
56 			break;
57 		}
58 
59 		sk_mem_charge(sk, size);
60 		atomic_add(size, &sk->sk_rmem_alloc);
61 		sk_msg_xfer(tmp, msg, i, size);
62 		copied += size;
63 		if (sge->length)
64 			get_page(sk_msg_page(tmp, i));
65 		sk_msg_iter_var_next(i);
66 		tmp->sg.end = i;
67 		if (apply) {
68 			apply_bytes -= size;
69 			if (!apply_bytes) {
70 				if (sge->length)
71 					sk_msg_iter_var_prev(i);
72 				break;
73 			}
74 		}
75 	} while (i != msg->sg.end);
76 
77 	if (!ret) {
78 		msg->sg.start = i;
79 		if (!sk_psock_queue_msg(psock, tmp))
80 			atomic_sub(copied, &sk->sk_rmem_alloc);
81 		sk_psock_data_ready(sk, psock);
82 	} else {
83 		sk_msg_free(sk, tmp);
84 		kfree(tmp);
85 	}
86 
87 	release_sock(sk);
88 	return ret;
89 }
90 
91 static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
92 			int flags, bool uncharge)
93 {
94 	struct msghdr msghdr = {};
95 	bool apply = apply_bytes;
96 	struct scatterlist *sge;
97 	struct page *page;
98 	int size, ret = 0;
99 	u32 off;
100 
101 	while (1) {
102 		struct bio_vec bvec;
103 		bool has_tx_ulp;
104 
105 		sge = sk_msg_elem(msg, msg->sg.start);
106 		size = (apply && apply_bytes < sge->length) ?
107 			apply_bytes : sge->length;
108 		off  = sge->offset;
109 		page = sg_page(sge);
110 
111 		tcp_rate_check_app_limited(sk);
112 retry:
113 		msghdr.msg_flags = flags | MSG_SPLICE_PAGES;
114 		has_tx_ulp = tls_sw_has_ctx_tx(sk);
115 		if (has_tx_ulp)
116 			msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
117 
118 		if (size < sge->length && msg->sg.start != msg->sg.end)
119 			msghdr.msg_flags |= MSG_MORE;
120 
121 		bvec_set_page(&bvec, page, size, off);
122 		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
123 		ret = tcp_sendmsg_locked(sk, &msghdr, size);
124 		if (ret <= 0)
125 			return ret;
126 
127 		if (apply)
128 			apply_bytes -= ret;
129 		msg->sg.size -= ret;
130 		sge->offset += ret;
131 		sge->length -= ret;
132 		if (uncharge)
133 			sk_mem_uncharge(sk, ret);
134 		if (ret != size) {
135 			size -= ret;
136 			off  += ret;
137 			goto retry;
138 		}
139 		if (!sge->length) {
140 			put_page(page);
141 			sk_msg_iter_next(msg, start);
142 			sg_init_table(sge, 1);
143 			if (msg->sg.start == msg->sg.end)
144 				break;
145 		}
146 		if (apply && !apply_bytes)
147 			break;
148 	}
149 
150 	return 0;
151 }
152 
153 static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
154 			       u32 apply_bytes, int flags, bool uncharge)
155 {
156 	int ret;
157 
158 	lock_sock(sk);
159 	ret = tcp_bpf_push(sk, msg, apply_bytes, flags, uncharge);
160 	release_sock(sk);
161 	return ret;
162 }
163 
164 int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
165 			  struct sk_msg *msg, u32 bytes, int flags)
166 {
167 	struct sk_psock *psock = sk_psock_get(sk);
168 	int ret;
169 
170 	if (unlikely(!psock))
171 		return -EPIPE;
172 
173 	ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes) :
174 			tcp_bpf_push_locked(sk, msg, bytes, flags, false);
175 	sk_psock_put(sk, psock);
176 	return ret;
177 }
178 EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
179 
180 #ifdef CONFIG_BPF_SYSCALL
181 static int tcp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
182 			     long timeo)
183 {
184 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
185 	int ret = 0;
186 
187 	if (sk->sk_shutdown & RCV_SHUTDOWN)
188 		return 1;
189 
190 	if (!timeo)
191 		return ret;
192 
193 	add_wait_queue(sk_sleep(sk), &wait);
194 	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
195 	ret = sk_wait_event(sk, &timeo,
196 			    !list_empty(&psock->ingress_msg) ||
197 			    !skb_queue_empty_lockless(&sk->sk_receive_queue), &wait);
198 	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
199 	remove_wait_queue(sk_sleep(sk), &wait);
200 	return ret;
201 }
202 
203 static bool is_next_msg_fin(struct sk_psock *psock)
204 {
205 	struct scatterlist *sge;
206 	struct sk_msg *msg_rx;
207 	int i;
208 
209 	msg_rx = sk_psock_peek_msg(psock);
210 	i = msg_rx->sg.start;
211 	sge = sk_msg_elem(msg_rx, i);
212 	if (!sge->length) {
213 		struct sk_buff *skb = msg_rx->skb;
214 
215 		if (skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
216 			return true;
217 	}
218 	return false;
219 }
220 
221 static int tcp_bpf_recvmsg_parser(struct sock *sk,
222 				  struct msghdr *msg,
223 				  size_t len,
224 				  int flags)
225 {
226 	int peek = flags & MSG_PEEK;
227 	struct sk_psock *psock;
228 	struct tcp_sock *tcp;
229 	int copied_from_self = 0;
230 	int copied = 0;
231 	u32 seq;
232 
233 	if (unlikely(flags & MSG_ERRQUEUE))
234 		return inet_recv_error(sk, msg, len);
235 
236 	if (!len)
237 		return 0;
238 
239 	psock = sk_psock_get(sk);
240 	if (unlikely(!psock))
241 		return tcp_recvmsg(sk, msg, len, flags);
242 
243 	lock_sock(sk);
244 	tcp = tcp_sk(sk);
245 	seq = tcp->copied_seq;
246 	/* We may have received data on the sk_receive_queue pre-accept and
247 	 * then we can not use read_skb in this context because we haven't
248 	 * assigned a sk_socket yet so have no link to the ops. The work-around
249 	 * is to check the sk_receive_queue and in these cases read skbs off
250 	 * queue again. The read_skb hook is not running at this point because
251 	 * of lock_sock so we avoid having multiple runners in read_skb.
252 	 */
253 	if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
254 		tcp_data_ready(sk);
255 		/* This handles the ENOMEM errors if we both receive data
256 		 * pre accept and are already under memory pressure. At least
257 		 * let user know to retry.
258 		 */
259 		if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
260 			copied = -EAGAIN;
261 			goto out;
262 		}
263 	}
264 
265 msg_bytes_ready:
266 	copied = __sk_msg_recvmsg(sk, psock, msg, len, flags, &copied_from_self);
267 	/* The typical case for EFAULT is the socket was gracefully
268 	 * shutdown with a FIN pkt. So check here the other case is
269 	 * some error on copy_page_to_iter which would be unexpected.
270 	 * On fin return correct return code to zero.
271 	 */
272 	if (copied == -EFAULT) {
273 		bool is_fin = is_next_msg_fin(psock);
274 
275 		if (is_fin) {
276 			copied = 0;
277 			seq++;
278 			goto out;
279 		}
280 	}
281 	seq += copied_from_self;
282 	if (!copied) {
283 		long timeo;
284 		int data;
285 
286 		if (sock_flag(sk, SOCK_DONE))
287 			goto out;
288 
289 		copied = sock_error(sk);
290 		if (copied)
291 			goto out;
292 
293 		if (sk->sk_shutdown & RCV_SHUTDOWN)
294 			goto out;
295 
296 		if (sk->sk_state == TCP_CLOSE) {
297 			copied = -ENOTCONN;
298 			goto out;
299 		}
300 
301 		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
302 		if (!timeo) {
303 			copied = -EAGAIN;
304 			goto out;
305 		}
306 
307 		if (signal_pending(current)) {
308 			copied = sock_intr_errno(timeo);
309 			goto out;
310 		}
311 
312 		data = tcp_msg_wait_data(sk, psock, timeo);
313 		if (data < 0) {
314 			copied = data;
315 			goto unlock;
316 		}
317 		if (data && !sk_psock_queue_empty(psock))
318 			goto msg_bytes_ready;
319 		copied = -EAGAIN;
320 	}
321 out:
322 	if (!peek)
323 		WRITE_ONCE(tcp->copied_seq, seq);
324 	tcp_rcv_space_adjust(sk);
325 	if (copied > 0)
326 		__tcp_cleanup_rbuf(sk, copied);
327 
328 unlock:
329 	release_sock(sk);
330 	sk_psock_put(sk, psock);
331 	return copied;
332 }
333 
334 static int tcp_bpf_ioctl(struct sock *sk, int cmd, int *karg)
335 {
336 	struct sk_psock *psock;
337 	bool slow;
338 
339 	if (cmd != SIOCINQ)
340 		return tcp_ioctl(sk, cmd, karg);
341 
342 	/* works similar as tcp_ioctl */
343 	if (sk->sk_state == TCP_LISTEN)
344 		return -EINVAL;
345 
346 	slow = lock_sock_fast(sk);
347 	psock = sk_psock_get(sk);
348 	if (unlikely(!psock)) {
349 		unlock_sock_fast(sk, slow);
350 		return tcp_ioctl(sk, cmd, karg);
351 	}
352 	*karg = sk_psock_get_msg_len_nolock(psock);
353 	/* Without a verdict program, ingress data is never diverted to
354 	 * ingress_msg: it stays in sk_receive_queue and is read through
355 	 * the fallback to tcp_recvmsg(), so account for it like
356 	 * tcp_ioctl() does.
357 	 */
358 	if (!READ_ONCE(psock->progs.stream_verdict) &&
359 	    !READ_ONCE(psock->progs.skb_verdict))
360 		*karg += tcp_inq(sk);
361 	sk_psock_put(sk, psock);
362 	unlock_sock_fast(sk, slow);
363 
364 	return 0;
365 }
366 
367 static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
368 			   int flags)
369 {
370 	struct sk_psock *psock;
371 	int copied, ret;
372 
373 	if (unlikely(flags & MSG_ERRQUEUE))
374 		return inet_recv_error(sk, msg, len);
375 
376 	if (!len)
377 		return 0;
378 
379 	psock = sk_psock_get(sk);
380 	if (unlikely(!psock))
381 		return tcp_recvmsg(sk, msg, len, flags);
382 	if (!skb_queue_empty(&sk->sk_receive_queue) &&
383 	    sk_psock_queue_empty(psock)) {
384 		sk_psock_put(sk, psock);
385 		return tcp_recvmsg(sk, msg, len, flags);
386 	}
387 	lock_sock(sk);
388 msg_bytes_ready:
389 	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
390 	if (!copied) {
391 		long timeo;
392 		int data;
393 
394 		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
395 		data = tcp_msg_wait_data(sk, psock, timeo);
396 		if (data < 0) {
397 			ret = data;
398 			goto unlock;
399 		}
400 		if (data) {
401 			if (!sk_psock_queue_empty(psock))
402 				goto msg_bytes_ready;
403 			release_sock(sk);
404 			sk_psock_put(sk, psock);
405 			return tcp_recvmsg(sk, msg, len, flags);
406 		}
407 		copied = -EAGAIN;
408 	}
409 	ret = copied;
410 
411 unlock:
412 	release_sock(sk);
413 	sk_psock_put(sk, psock);
414 	return ret;
415 }
416 
417 static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
418 				struct sk_msg *msg, int *copied, int flags)
419 {
420 	bool cork = false, enospc = sk_msg_full(msg), redir_ingress;
421 	struct sock *sk_redir;
422 	u32 tosend, origsize, sent, delta = 0;
423 	u32 eval;
424 	int ret;
425 
426 more_data:
427 	if (psock->eval == __SK_NONE) {
428 		/* Track delta in msg size to add/subtract it on SK_DROP from
429 		 * returned to user copied size. This ensures user doesn't
430 		 * get a positive return code with msg_cut_data and SK_DROP
431 		 * verdict.
432 		 */
433 		delta = msg->sg.size;
434 		psock->eval = sk_psock_msg_verdict(sk, psock, msg);
435 		delta -= msg->sg.size;
436 	}
437 
438 	if (msg->cork_bytes &&
439 	    msg->cork_bytes > msg->sg.size && !enospc) {
440 		psock->cork_bytes = msg->cork_bytes - msg->sg.size;
441 		if (!psock->cork) {
442 			psock->cork = kzalloc_obj(*psock->cork,
443 						  GFP_ATOMIC | __GFP_NOWARN);
444 			if (!psock->cork) {
445 				sk_msg_free(sk, msg);
446 				*copied = 0;
447 				return -ENOMEM;
448 			}
449 		}
450 		memcpy(psock->cork, msg, sizeof(*msg));
451 		return 0;
452 	}
453 
454 	tosend = msg->sg.size;
455 	if (psock->apply_bytes && psock->apply_bytes < tosend)
456 		tosend = psock->apply_bytes;
457 	eval = __SK_NONE;
458 
459 	switch (psock->eval) {
460 	case __SK_PASS:
461 		ret = tcp_bpf_push(sk, msg, tosend, flags, true);
462 		if (unlikely(ret)) {
463 			*copied -= sk_msg_free(sk, msg);
464 			break;
465 		}
466 		sk_msg_apply_bytes(psock, tosend);
467 		break;
468 	case __SK_REDIRECT:
469 		redir_ingress = psock->redir_ingress;
470 		sk_redir = psock->sk_redir;
471 		sock_hold(sk_redir);
472 		sk_msg_apply_bytes(psock, tosend);
473 		if (!psock->apply_bytes) {
474 			/* Clean up before releasing the sock lock. */
475 			eval = psock->eval;
476 			psock->eval = __SK_NONE;
477 			psock->sk_redir = NULL;
478 		}
479 		if (psock->cork) {
480 			cork = true;
481 			psock->cork = NULL;
482 		}
483 		release_sock(sk);
484 
485 		origsize = msg->sg.size;
486 		ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
487 					    msg, tosend, flags);
488 		sent = origsize - msg->sg.size;
489 
490 		if (eval == __SK_REDIRECT)
491 			sock_put(sk_redir);
492 		sock_put(sk_redir);
493 
494 		lock_sock(sk);
495 		sk_mem_uncharge(sk, sent);
496 		if (unlikely(ret < 0)) {
497 			int free = sk_msg_free(sk, msg);
498 
499 			if (!cork)
500 				*copied -= free;
501 		}
502 		if (cork) {
503 			sk_msg_free(sk, msg);
504 			kfree(msg);
505 			msg = NULL;
506 			ret = 0;
507 		}
508 		break;
509 	case __SK_DROP:
510 	default:
511 		sk_msg_free(sk, msg);
512 		sk_msg_apply_bytes(psock, tosend);
513 		*copied -= (tosend + delta);
514 		return -EACCES;
515 	}
516 
517 	if (likely(!ret)) {
518 		if (!psock->apply_bytes) {
519 			psock->eval =  __SK_NONE;
520 			if (psock->sk_redir) {
521 				sock_put(psock->sk_redir);
522 				psock->sk_redir = NULL;
523 			}
524 		}
525 		if (msg &&
526 		    msg->sg.data[msg->sg.start].page_link &&
527 		    msg->sg.data[msg->sg.start].length)
528 			goto more_data;
529 	}
530 	return ret;
531 }
532 
533 static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
534 {
535 	struct sk_msg tmp, *msg_tx = NULL;
536 	int copied = 0, err = 0, ret = 0;
537 	struct sk_psock *psock;
538 	long timeo;
539 	int flags;
540 
541 	/* Don't let internal flags through */
542 	flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
543 	flags |= MSG_NO_SHARED_FRAGS;
544 
545 	psock = sk_psock_get(sk);
546 	if (unlikely(!psock))
547 		return tcp_sendmsg(sk, msg, size);
548 
549 	lock_sock(sk);
550 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
551 	while (msg_data_left(msg)) {
552 		bool enospc = false;
553 		u32 copy, osize;
554 
555 		err = -READ_ONCE(sk->sk_err);
556 		if (err)
557 			goto out_err;
558 
559 		copy = msg_data_left(msg);
560 		if (!sk_stream_memory_free(sk))
561 			goto wait_for_sndbuf;
562 		if (psock->cork) {
563 			msg_tx = psock->cork;
564 		} else {
565 			msg_tx = &tmp;
566 			sk_msg_init(msg_tx);
567 		}
568 
569 		osize = msg_tx->sg.size;
570 		err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
571 		if (err) {
572 			if (err != -ENOSPC)
573 				goto wait_for_memory;
574 			enospc = true;
575 			copy = msg_tx->sg.size - osize;
576 		}
577 
578 		ret = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx,
579 					       copy);
580 		if (ret < 0) {
581 			sk_msg_trim(sk, msg_tx, osize);
582 			err = ret;
583 			goto out_err;
584 		}
585 
586 		copied += ret;
587 		if (psock->cork_bytes) {
588 			if (size > psock->cork_bytes)
589 				psock->cork_bytes = 0;
590 			else
591 				psock->cork_bytes -= size;
592 			if (psock->cork_bytes && !enospc)
593 				goto out_err;
594 			/* All cork bytes are accounted, rerun the prog. */
595 			psock->eval = __SK_NONE;
596 			psock->cork_bytes = 0;
597 		}
598 
599 		err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags);
600 		if (unlikely(err < 0))
601 			goto out_err;
602 		continue;
603 wait_for_sndbuf:
604 		sk_set_nospace(sk);
605 wait_for_memory:
606 		err = sk_stream_wait_memory(sk, &timeo);
607 		if (err) {
608 			if (msg_tx == &tmp)
609 				sk_msg_free(sk, msg_tx);
610 			goto out_err;
611 		}
612 	}
613 out_err:
614 	if (err < 0)
615 		err = sk_stream_error(sk, msg->msg_flags, err);
616 	release_sock(sk);
617 	sk_psock_put(sk, psock);
618 	return copied > 0 ? copied : err;
619 }
620 
621 enum {
622 	TCP_BPF_IPV4,
623 	TCP_BPF_IPV6,
624 	TCP_BPF_NUM_PROTS,
625 };
626 
627 enum {
628 	TCP_BPF_BASE,
629 	TCP_BPF_TX,
630 	TCP_BPF_RX,
631 	TCP_BPF_TXRX,
632 	TCP_BPF_NUM_CFGS,
633 };
634 
635 static struct proto *tcpv6_prot_saved __read_mostly;
636 static DEFINE_SPINLOCK(tcpv6_prot_lock);
637 static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
638 
639 static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
640 				   struct proto *base)
641 {
642 	prot[TCP_BPF_BASE]			= *base;
643 	prot[TCP_BPF_BASE].destroy		= sock_map_destroy;
644 	prot[TCP_BPF_BASE].close		= sock_map_close;
645 	prot[TCP_BPF_BASE].recvmsg		= tcp_bpf_recvmsg;
646 	prot[TCP_BPF_BASE].sock_is_readable	= sk_msg_is_readable;
647 	prot[TCP_BPF_BASE].ioctl		= tcp_bpf_ioctl;
648 
649 	prot[TCP_BPF_TX]			= prot[TCP_BPF_BASE];
650 	prot[TCP_BPF_TX].sendmsg		= tcp_bpf_sendmsg;
651 
652 	prot[TCP_BPF_RX]			= prot[TCP_BPF_BASE];
653 	prot[TCP_BPF_RX].recvmsg		= tcp_bpf_recvmsg_parser;
654 
655 	prot[TCP_BPF_TXRX]			= prot[TCP_BPF_TX];
656 	prot[TCP_BPF_TXRX].recvmsg		= tcp_bpf_recvmsg_parser;
657 }
658 
659 static void tcp_bpf_check_v6_needs_rebuild(struct proto *ops)
660 {
661 	if (unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
662 		spin_lock_bh(&tcpv6_prot_lock);
663 		if (likely(ops != tcpv6_prot_saved)) {
664 			tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
665 			smp_store_release(&tcpv6_prot_saved, ops);
666 		}
667 		spin_unlock_bh(&tcpv6_prot_lock);
668 	}
669 }
670 
671 static int __init tcp_bpf_v4_build_proto(void)
672 {
673 	tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
674 	return 0;
675 }
676 late_initcall(tcp_bpf_v4_build_proto);
677 
678 static int tcp_bpf_assert_proto_ops(struct proto *ops)
679 {
680 	/* In order to avoid retpoline, we make assumptions when we call
681 	 * into ops if e.g. a psock is not present. Make sure they are
682 	 * indeed valid assumptions.
683 	 */
684 	return ops->recvmsg  == tcp_recvmsg &&
685 	       ops->sendmsg  == tcp_sendmsg ? 0 : -ENOTSUPP;
686 }
687 
688 #if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
689 int tcp_bpf_strp_read_sock(struct strparser *strp, read_descriptor_t *desc,
690 			   sk_read_actor_t recv_actor)
691 {
692 	struct sock *sk = strp->sk;
693 	struct sk_psock *psock;
694 	struct tcp_sock *tp;
695 	int copied = 0;
696 
697 	tp = tcp_sk(sk);
698 	rcu_read_lock();
699 	psock = sk_psock(sk);
700 	if (WARN_ON_ONCE(!psock)) {
701 		desc->error = -EINVAL;
702 		goto out;
703 	}
704 
705 	psock->ingress_bytes = 0;
706 	copied = tcp_read_sock_noack(sk, desc, recv_actor, true,
707 				     &psock->copied_seq);
708 	if (copied < 0)
709 		goto out;
710 	/* recv_actor may redirect skb to another socket (SK_REDIRECT) or
711 	 * just put skb into ingress queue of current socket (SK_PASS).
712 	 * For SK_REDIRECT, we need to ack the frame immediately but for
713 	 * SK_PASS, we want to delay the ack until tcp_bpf_recvmsg_parser().
714 	 */
715 	tp->copied_seq = psock->copied_seq - psock->ingress_bytes;
716 	tcp_rcv_space_adjust(sk);
717 	__tcp_cleanup_rbuf(sk, copied - psock->ingress_bytes);
718 out:
719 	rcu_read_unlock();
720 	return copied;
721 }
722 #endif /* CONFIG_BPF_STREAM_PARSER */
723 
724 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
725 {
726 	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
727 	int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
728 
729 	if (psock->progs.stream_verdict || psock->progs.skb_verdict) {
730 		config = (config == TCP_BPF_TX) ? TCP_BPF_TXRX : TCP_BPF_RX;
731 	}
732 
733 	if (restore) {
734 		if (inet_csk_has_ulp(sk)) {
735 			/* TLS does not have an unhash proto in SW cases,
736 			 * but we need to ensure we stop using the sock_map
737 			 * unhash routine because the associated psock is being
738 			 * removed. So use the original unhash handler.
739 			 */
740 			WRITE_ONCE(sk->sk_prot->unhash, psock->saved_unhash);
741 			tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
742 		} else {
743 			WRITE_ONCE(sk->sk_write_space, psock->saved_write_space);
744 			/* Pairs with lockless read in sk_clone_lock() */
745 			sock_replace_proto(sk, psock->sk_proto);
746 		}
747 		return 0;
748 	}
749 
750 	if (sk->sk_family == AF_INET6) {
751 		if (tcp_bpf_assert_proto_ops(psock->sk_proto))
752 			return -EINVAL;
753 
754 		tcp_bpf_check_v6_needs_rebuild(psock->sk_proto);
755 	}
756 
757 	/* Pairs with lockless read in sk_clone_lock() */
758 	sock_replace_proto(sk, &tcp_bpf_prots[family][config]);
759 	return 0;
760 }
761 EXPORT_SYMBOL_GPL(tcp_bpf_update_proto);
762 
763 /* If a child got cloned from a listening socket that had tcp_bpf
764  * protocol callbacks installed, we need to restore the callbacks to
765  * the default ones because the child does not inherit the psock state
766  * that tcp_bpf callbacks expect.
767  */
768 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
769 {
770 	struct proto *prot = newsk->sk_prot;
771 
772 	if (is_insidevar(prot, tcp_bpf_prots))
773 		newsk->sk_prot = sk->sk_prot_creator;
774 }
775 #endif /* CONFIG_BPF_SYSCALL */
776