xref: /linux/net/ipv4/tcp_bpf.c (revision 5635f189425e328097714c38341944fc40731f3d)
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 
tcp_eat_skb(struct sock * sk,struct sk_buff * skb)14 void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
15 {
16 	struct tcp_sock *tcp;
17 	int copied;
18 
19 	if (!skb || !skb->len || !sk_is_tcp(sk))
20 		return;
21 
22 	if (skb_bpf_strparser(skb))
23 		return;
24 
25 	tcp = tcp_sk(sk);
26 	copied = tcp->copied_seq + skb->len;
27 	WRITE_ONCE(tcp->copied_seq, copied);
28 	tcp_rcv_space_adjust(sk);
29 	__tcp_cleanup_rbuf(sk, skb->len);
30 }
31 
bpf_tcp_ingress(struct sock * sk,struct sk_psock * psock,struct sk_msg * msg,u32 apply_bytes)32 static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
33 			   struct sk_msg *msg, u32 apply_bytes)
34 {
35 	bool apply = apply_bytes;
36 	struct scatterlist *sge;
37 	u32 size, copied = 0;
38 	struct sk_msg *tmp;
39 	int i, ret = 0;
40 
41 	tmp = kzalloc(sizeof(*tmp), __GFP_NOWARN | GFP_KERNEL);
42 	if (unlikely(!tmp))
43 		return -ENOMEM;
44 
45 	lock_sock(sk);
46 	tmp->sg.start = msg->sg.start;
47 	i = msg->sg.start;
48 	do {
49 		sge = sk_msg_elem(msg, i);
50 		size = (apply && apply_bytes < sge->length) ?
51 			apply_bytes : sge->length;
52 		if (!sk_wmem_schedule(sk, size)) {
53 			if (!copied)
54 				ret = -ENOMEM;
55 			break;
56 		}
57 
58 		sk_mem_charge(sk, size);
59 		sk_msg_xfer(tmp, msg, i, size);
60 		copied += size;
61 		if (sge->length)
62 			get_page(sk_msg_page(tmp, i));
63 		sk_msg_iter_var_next(i);
64 		tmp->sg.end = i;
65 		if (apply) {
66 			apply_bytes -= size;
67 			if (!apply_bytes) {
68 				if (sge->length)
69 					sk_msg_iter_var_prev(i);
70 				break;
71 			}
72 		}
73 	} while (i != msg->sg.end);
74 
75 	if (!ret) {
76 		msg->sg.start = i;
77 		sk_psock_queue_msg(psock, tmp);
78 		sk_psock_data_ready(sk, psock);
79 	} else {
80 		sk_msg_free(sk, tmp);
81 		kfree(tmp);
82 	}
83 
84 	release_sock(sk);
85 	return ret;
86 }
87 
tcp_bpf_push(struct sock * sk,struct sk_msg * msg,u32 apply_bytes,int flags,bool uncharge)88 static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
89 			int flags, bool uncharge)
90 {
91 	struct msghdr msghdr = {};
92 	bool apply = apply_bytes;
93 	struct scatterlist *sge;
94 	struct page *page;
95 	int size, ret = 0;
96 	u32 off;
97 
98 	while (1) {
99 		struct bio_vec bvec;
100 		bool has_tx_ulp;
101 
102 		sge = sk_msg_elem(msg, msg->sg.start);
103 		size = (apply && apply_bytes < sge->length) ?
104 			apply_bytes : sge->length;
105 		off  = sge->offset;
106 		page = sg_page(sge);
107 
108 		tcp_rate_check_app_limited(sk);
109 retry:
110 		msghdr.msg_flags = flags | MSG_SPLICE_PAGES;
111 		has_tx_ulp = tls_sw_has_ctx_tx(sk);
112 		if (has_tx_ulp)
113 			msghdr.msg_flags |= MSG_SENDPAGE_NOPOLICY;
114 
115 		if (size < sge->length && msg->sg.start != msg->sg.end)
116 			msghdr.msg_flags |= MSG_MORE;
117 
118 		bvec_set_page(&bvec, page, size, off);
119 		iov_iter_bvec(&msghdr.msg_iter, ITER_SOURCE, &bvec, 1, size);
120 		ret = tcp_sendmsg_locked(sk, &msghdr, size);
121 		if (ret <= 0)
122 			return ret;
123 
124 		if (apply)
125 			apply_bytes -= ret;
126 		msg->sg.size -= ret;
127 		sge->offset += ret;
128 		sge->length -= ret;
129 		if (uncharge)
130 			sk_mem_uncharge(sk, ret);
131 		if (ret != size) {
132 			size -= ret;
133 			off  += ret;
134 			goto retry;
135 		}
136 		if (!sge->length) {
137 			put_page(page);
138 			sk_msg_iter_next(msg, start);
139 			sg_init_table(sge, 1);
140 			if (msg->sg.start == msg->sg.end)
141 				break;
142 		}
143 		if (apply && !apply_bytes)
144 			break;
145 	}
146 
147 	return 0;
148 }
149 
tcp_bpf_push_locked(struct sock * sk,struct sk_msg * msg,u32 apply_bytes,int flags,bool uncharge)150 static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
151 			       u32 apply_bytes, int flags, bool uncharge)
152 {
153 	int ret;
154 
155 	lock_sock(sk);
156 	ret = tcp_bpf_push(sk, msg, apply_bytes, flags, uncharge);
157 	release_sock(sk);
158 	return ret;
159 }
160 
tcp_bpf_sendmsg_redir(struct sock * sk,bool ingress,struct sk_msg * msg,u32 bytes,int flags)161 int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
162 			  struct sk_msg *msg, u32 bytes, int flags)
163 {
164 	struct sk_psock *psock = sk_psock_get(sk);
165 	int ret;
166 
167 	if (unlikely(!psock))
168 		return -EPIPE;
169 
170 	ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes) :
171 			tcp_bpf_push_locked(sk, msg, bytes, flags, false);
172 	sk_psock_put(sk, psock);
173 	return ret;
174 }
175 EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
176 
177 #ifdef CONFIG_BPF_SYSCALL
tcp_msg_wait_data(struct sock * sk,struct sk_psock * psock,long timeo)178 static int tcp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
179 			     long timeo)
180 {
181 	DEFINE_WAIT_FUNC(wait, woken_wake_function);
182 	int ret = 0;
183 
184 	if (sk->sk_shutdown & RCV_SHUTDOWN)
185 		return 1;
186 
187 	if (!timeo)
188 		return ret;
189 
190 	add_wait_queue(sk_sleep(sk), &wait);
191 	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
192 	ret = sk_wait_event(sk, &timeo,
193 			    !list_empty(&psock->ingress_msg) ||
194 			    !skb_queue_empty_lockless(&sk->sk_receive_queue), &wait);
195 	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
196 	remove_wait_queue(sk_sleep(sk), &wait);
197 	return ret;
198 }
199 
is_next_msg_fin(struct sk_psock * psock)200 static bool is_next_msg_fin(struct sk_psock *psock)
201 {
202 	struct scatterlist *sge;
203 	struct sk_msg *msg_rx;
204 	int i;
205 
206 	msg_rx = sk_psock_peek_msg(psock);
207 	i = msg_rx->sg.start;
208 	sge = sk_msg_elem(msg_rx, i);
209 	if (!sge->length) {
210 		struct sk_buff *skb = msg_rx->skb;
211 
212 		if (skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
213 			return true;
214 	}
215 	return false;
216 }
217 
tcp_bpf_recvmsg_parser(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)218 static int tcp_bpf_recvmsg_parser(struct sock *sk,
219 				  struct msghdr *msg,
220 				  size_t len,
221 				  int flags,
222 				  int *addr_len)
223 {
224 	int peek = flags & MSG_PEEK;
225 	struct sk_psock *psock;
226 	struct tcp_sock *tcp;
227 	int copied = 0;
228 	u32 seq;
229 
230 	if (unlikely(flags & MSG_ERRQUEUE))
231 		return inet_recv_error(sk, msg, len, addr_len);
232 
233 	if (!len)
234 		return 0;
235 
236 	psock = sk_psock_get(sk);
237 	if (unlikely(!psock))
238 		return tcp_recvmsg(sk, msg, len, flags, addr_len);
239 
240 	lock_sock(sk);
241 	tcp = tcp_sk(sk);
242 	seq = tcp->copied_seq;
243 	/* We may have received data on the sk_receive_queue pre-accept and
244 	 * then we can not use read_skb in this context because we haven't
245 	 * assigned a sk_socket yet so have no link to the ops. The work-around
246 	 * is to check the sk_receive_queue and in these cases read skbs off
247 	 * queue again. The read_skb hook is not running at this point because
248 	 * of lock_sock so we avoid having multiple runners in read_skb.
249 	 */
250 	if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
251 		tcp_data_ready(sk);
252 		/* This handles the ENOMEM errors if we both receive data
253 		 * pre accept and are already under memory pressure. At least
254 		 * let user know to retry.
255 		 */
256 		if (unlikely(!skb_queue_empty(&sk->sk_receive_queue))) {
257 			copied = -EAGAIN;
258 			goto out;
259 		}
260 	}
261 
262 msg_bytes_ready:
263 	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
264 	/* The typical case for EFAULT is the socket was gracefully
265 	 * shutdown with a FIN pkt. So check here the other case is
266 	 * some error on copy_page_to_iter which would be unexpected.
267 	 * On fin return correct return code to zero.
268 	 */
269 	if (copied == -EFAULT) {
270 		bool is_fin = is_next_msg_fin(psock);
271 
272 		if (is_fin) {
273 			copied = 0;
274 			seq++;
275 			goto out;
276 		}
277 	}
278 	seq += copied;
279 	if (!copied) {
280 		long timeo;
281 		int data;
282 
283 		if (sock_flag(sk, SOCK_DONE))
284 			goto out;
285 
286 		if (sk->sk_err) {
287 			copied = sock_error(sk);
288 			goto out;
289 		}
290 
291 		if (sk->sk_shutdown & RCV_SHUTDOWN)
292 			goto out;
293 
294 		if (sk->sk_state == TCP_CLOSE) {
295 			copied = -ENOTCONN;
296 			goto out;
297 		}
298 
299 		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
300 		if (!timeo) {
301 			copied = -EAGAIN;
302 			goto out;
303 		}
304 
305 		if (signal_pending(current)) {
306 			copied = sock_intr_errno(timeo);
307 			goto out;
308 		}
309 
310 		data = tcp_msg_wait_data(sk, psock, timeo);
311 		if (data < 0) {
312 			copied = data;
313 			goto unlock;
314 		}
315 		if (data && !sk_psock_queue_empty(psock))
316 			goto msg_bytes_ready;
317 		copied = -EAGAIN;
318 	}
319 out:
320 	if (!peek)
321 		WRITE_ONCE(tcp->copied_seq, seq);
322 	tcp_rcv_space_adjust(sk);
323 	if (copied > 0)
324 		__tcp_cleanup_rbuf(sk, copied);
325 
326 unlock:
327 	release_sock(sk);
328 	sk_psock_put(sk, psock);
329 	return copied;
330 }
331 
tcp_bpf_recvmsg(struct sock * sk,struct msghdr * msg,size_t len,int flags,int * addr_len)332 static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
333 			   int flags, int *addr_len)
334 {
335 	struct sk_psock *psock;
336 	int copied, ret;
337 
338 	if (unlikely(flags & MSG_ERRQUEUE))
339 		return inet_recv_error(sk, msg, len, addr_len);
340 
341 	if (!len)
342 		return 0;
343 
344 	psock = sk_psock_get(sk);
345 	if (unlikely(!psock))
346 		return tcp_recvmsg(sk, msg, len, flags, addr_len);
347 	if (!skb_queue_empty(&sk->sk_receive_queue) &&
348 	    sk_psock_queue_empty(psock)) {
349 		sk_psock_put(sk, psock);
350 		return tcp_recvmsg(sk, msg, len, flags, addr_len);
351 	}
352 	lock_sock(sk);
353 msg_bytes_ready:
354 	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
355 	if (!copied) {
356 		long timeo;
357 		int data;
358 
359 		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
360 		data = tcp_msg_wait_data(sk, psock, timeo);
361 		if (data < 0) {
362 			ret = data;
363 			goto unlock;
364 		}
365 		if (data) {
366 			if (!sk_psock_queue_empty(psock))
367 				goto msg_bytes_ready;
368 			release_sock(sk);
369 			sk_psock_put(sk, psock);
370 			return tcp_recvmsg(sk, msg, len, flags, addr_len);
371 		}
372 		copied = -EAGAIN;
373 	}
374 	ret = copied;
375 
376 unlock:
377 	release_sock(sk);
378 	sk_psock_put(sk, psock);
379 	return ret;
380 }
381 
tcp_bpf_send_verdict(struct sock * sk,struct sk_psock * psock,struct sk_msg * msg,int * copied,int flags)382 static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
383 				struct sk_msg *msg, int *copied, int flags)
384 {
385 	bool cork = false, enospc = sk_msg_full(msg), redir_ingress;
386 	struct sock *sk_redir;
387 	u32 tosend, origsize, sent, delta = 0;
388 	u32 eval;
389 	int ret;
390 
391 more_data:
392 	if (psock->eval == __SK_NONE) {
393 		/* Track delta in msg size to add/subtract it on SK_DROP from
394 		 * returned to user copied size. This ensures user doesn't
395 		 * get a positive return code with msg_cut_data and SK_DROP
396 		 * verdict.
397 		 */
398 		delta = msg->sg.size;
399 		psock->eval = sk_psock_msg_verdict(sk, psock, msg);
400 		delta -= msg->sg.size;
401 	}
402 
403 	if (msg->cork_bytes &&
404 	    msg->cork_bytes > msg->sg.size && !enospc) {
405 		psock->cork_bytes = msg->cork_bytes - msg->sg.size;
406 		if (!psock->cork) {
407 			psock->cork = kzalloc(sizeof(*psock->cork),
408 					      GFP_ATOMIC | __GFP_NOWARN);
409 			if (!psock->cork)
410 				return -ENOMEM;
411 		}
412 		memcpy(psock->cork, msg, sizeof(*msg));
413 		return 0;
414 	}
415 
416 	tosend = msg->sg.size;
417 	if (psock->apply_bytes && psock->apply_bytes < tosend)
418 		tosend = psock->apply_bytes;
419 	eval = __SK_NONE;
420 
421 	switch (psock->eval) {
422 	case __SK_PASS:
423 		ret = tcp_bpf_push(sk, msg, tosend, flags, true);
424 		if (unlikely(ret)) {
425 			*copied -= sk_msg_free(sk, msg);
426 			break;
427 		}
428 		sk_msg_apply_bytes(psock, tosend);
429 		break;
430 	case __SK_REDIRECT:
431 		redir_ingress = psock->redir_ingress;
432 		sk_redir = psock->sk_redir;
433 		sk_msg_apply_bytes(psock, tosend);
434 		if (!psock->apply_bytes) {
435 			/* Clean up before releasing the sock lock. */
436 			eval = psock->eval;
437 			psock->eval = __SK_NONE;
438 			psock->sk_redir = NULL;
439 		}
440 		if (psock->cork) {
441 			cork = true;
442 			psock->cork = NULL;
443 		}
444 		sk_msg_return(sk, msg, tosend);
445 		release_sock(sk);
446 
447 		origsize = msg->sg.size;
448 		ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
449 					    msg, tosend, flags);
450 		sent = origsize - msg->sg.size;
451 
452 		if (eval == __SK_REDIRECT)
453 			sock_put(sk_redir);
454 
455 		lock_sock(sk);
456 		if (unlikely(ret < 0)) {
457 			int free = sk_msg_free_nocharge(sk, msg);
458 
459 			if (!cork)
460 				*copied -= free;
461 		}
462 		if (cork) {
463 			sk_msg_free(sk, msg);
464 			kfree(msg);
465 			msg = NULL;
466 			ret = 0;
467 		}
468 		break;
469 	case __SK_DROP:
470 	default:
471 		sk_msg_free_partial(sk, msg, tosend);
472 		sk_msg_apply_bytes(psock, tosend);
473 		*copied -= (tosend + delta);
474 		return -EACCES;
475 	}
476 
477 	if (likely(!ret)) {
478 		if (!psock->apply_bytes) {
479 			psock->eval =  __SK_NONE;
480 			if (psock->sk_redir) {
481 				sock_put(psock->sk_redir);
482 				psock->sk_redir = NULL;
483 			}
484 		}
485 		if (msg &&
486 		    msg->sg.data[msg->sg.start].page_link &&
487 		    msg->sg.data[msg->sg.start].length) {
488 			if (eval == __SK_REDIRECT)
489 				sk_mem_charge(sk, tosend - sent);
490 			goto more_data;
491 		}
492 	}
493 	return ret;
494 }
495 
tcp_bpf_sendmsg(struct sock * sk,struct msghdr * msg,size_t size)496 static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
497 {
498 	struct sk_msg tmp, *msg_tx = NULL;
499 	int copied = 0, err = 0;
500 	struct sk_psock *psock;
501 	long timeo;
502 	int flags;
503 
504 	/* Don't let internal flags through */
505 	flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED);
506 	flags |= MSG_NO_SHARED_FRAGS;
507 
508 	psock = sk_psock_get(sk);
509 	if (unlikely(!psock))
510 		return tcp_sendmsg(sk, msg, size);
511 
512 	lock_sock(sk);
513 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
514 	while (msg_data_left(msg)) {
515 		bool enospc = false;
516 		u32 copy, osize;
517 
518 		if (sk->sk_err) {
519 			err = -sk->sk_err;
520 			goto out_err;
521 		}
522 
523 		copy = msg_data_left(msg);
524 		if (!sk_stream_memory_free(sk))
525 			goto wait_for_sndbuf;
526 		if (psock->cork) {
527 			msg_tx = psock->cork;
528 		} else {
529 			msg_tx = &tmp;
530 			sk_msg_init(msg_tx);
531 		}
532 
533 		osize = msg_tx->sg.size;
534 		err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
535 		if (err) {
536 			if (err != -ENOSPC)
537 				goto wait_for_memory;
538 			enospc = true;
539 			copy = msg_tx->sg.size - osize;
540 		}
541 
542 		err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx,
543 					       copy);
544 		if (err < 0) {
545 			sk_msg_trim(sk, msg_tx, osize);
546 			goto out_err;
547 		}
548 
549 		copied += copy;
550 		if (psock->cork_bytes) {
551 			if (size > psock->cork_bytes)
552 				psock->cork_bytes = 0;
553 			else
554 				psock->cork_bytes -= size;
555 			if (psock->cork_bytes && !enospc)
556 				goto out_err;
557 			/* All cork bytes are accounted, rerun the prog. */
558 			psock->eval = __SK_NONE;
559 			psock->cork_bytes = 0;
560 		}
561 
562 		err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags);
563 		if (unlikely(err < 0))
564 			goto out_err;
565 		continue;
566 wait_for_sndbuf:
567 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
568 wait_for_memory:
569 		err = sk_stream_wait_memory(sk, &timeo);
570 		if (err) {
571 			if (msg_tx && msg_tx != psock->cork)
572 				sk_msg_free(sk, msg_tx);
573 			goto out_err;
574 		}
575 	}
576 out_err:
577 	if (err < 0)
578 		err = sk_stream_error(sk, msg->msg_flags, err);
579 	release_sock(sk);
580 	sk_psock_put(sk, psock);
581 	return copied > 0 ? copied : err;
582 }
583 
584 enum {
585 	TCP_BPF_IPV4,
586 	TCP_BPF_IPV6,
587 	TCP_BPF_NUM_PROTS,
588 };
589 
590 enum {
591 	TCP_BPF_BASE,
592 	TCP_BPF_TX,
593 	TCP_BPF_RX,
594 	TCP_BPF_TXRX,
595 	TCP_BPF_NUM_CFGS,
596 };
597 
598 static struct proto *tcpv6_prot_saved __read_mostly;
599 static DEFINE_SPINLOCK(tcpv6_prot_lock);
600 static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
601 
tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],struct proto * base)602 static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
603 				   struct proto *base)
604 {
605 	prot[TCP_BPF_BASE]			= *base;
606 	prot[TCP_BPF_BASE].destroy		= sock_map_destroy;
607 	prot[TCP_BPF_BASE].close		= sock_map_close;
608 	prot[TCP_BPF_BASE].recvmsg		= tcp_bpf_recvmsg;
609 	prot[TCP_BPF_BASE].sock_is_readable	= sk_msg_is_readable;
610 
611 	prot[TCP_BPF_TX]			= prot[TCP_BPF_BASE];
612 	prot[TCP_BPF_TX].sendmsg		= tcp_bpf_sendmsg;
613 
614 	prot[TCP_BPF_RX]			= prot[TCP_BPF_BASE];
615 	prot[TCP_BPF_RX].recvmsg		= tcp_bpf_recvmsg_parser;
616 
617 	prot[TCP_BPF_TXRX]			= prot[TCP_BPF_TX];
618 	prot[TCP_BPF_TXRX].recvmsg		= tcp_bpf_recvmsg_parser;
619 }
620 
tcp_bpf_check_v6_needs_rebuild(struct proto * ops)621 static void tcp_bpf_check_v6_needs_rebuild(struct proto *ops)
622 {
623 	if (unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
624 		spin_lock_bh(&tcpv6_prot_lock);
625 		if (likely(ops != tcpv6_prot_saved)) {
626 			tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
627 			smp_store_release(&tcpv6_prot_saved, ops);
628 		}
629 		spin_unlock_bh(&tcpv6_prot_lock);
630 	}
631 }
632 
tcp_bpf_v4_build_proto(void)633 static int __init tcp_bpf_v4_build_proto(void)
634 {
635 	tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
636 	return 0;
637 }
638 late_initcall(tcp_bpf_v4_build_proto);
639 
tcp_bpf_assert_proto_ops(struct proto * ops)640 static int tcp_bpf_assert_proto_ops(struct proto *ops)
641 {
642 	/* In order to avoid retpoline, we make assumptions when we call
643 	 * into ops if e.g. a psock is not present. Make sure they are
644 	 * indeed valid assumptions.
645 	 */
646 	return ops->recvmsg  == tcp_recvmsg &&
647 	       ops->sendmsg  == tcp_sendmsg ? 0 : -ENOTSUPP;
648 }
649 
tcp_bpf_update_proto(struct sock * sk,struct sk_psock * psock,bool restore)650 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
651 {
652 	int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
653 	int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
654 
655 	if (psock->progs.stream_verdict || psock->progs.skb_verdict) {
656 		config = (config == TCP_BPF_TX) ? TCP_BPF_TXRX : TCP_BPF_RX;
657 	}
658 
659 	if (restore) {
660 		if (inet_csk_has_ulp(sk)) {
661 			/* TLS does not have an unhash proto in SW cases,
662 			 * but we need to ensure we stop using the sock_map
663 			 * unhash routine because the associated psock is being
664 			 * removed. So use the original unhash handler.
665 			 */
666 			WRITE_ONCE(sk->sk_prot->unhash, psock->saved_unhash);
667 			tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
668 		} else {
669 			sk->sk_write_space = psock->saved_write_space;
670 			/* Pairs with lockless read in sk_clone_lock() */
671 			sock_replace_proto(sk, psock->sk_proto);
672 		}
673 		return 0;
674 	}
675 
676 	if (sk->sk_family == AF_INET6) {
677 		if (tcp_bpf_assert_proto_ops(psock->sk_proto))
678 			return -EINVAL;
679 
680 		tcp_bpf_check_v6_needs_rebuild(psock->sk_proto);
681 	}
682 
683 	/* Pairs with lockless read in sk_clone_lock() */
684 	sock_replace_proto(sk, &tcp_bpf_prots[family][config]);
685 	return 0;
686 }
687 EXPORT_SYMBOL_GPL(tcp_bpf_update_proto);
688 
689 /* If a child got cloned from a listening socket that had tcp_bpf
690  * protocol callbacks installed, we need to restore the callbacks to
691  * the default ones because the child does not inherit the psock state
692  * that tcp_bpf callbacks expect.
693  */
tcp_bpf_clone(const struct sock * sk,struct sock * newsk)694 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
695 {
696 	struct proto *prot = newsk->sk_prot;
697 
698 	if (is_insidevar(prot, tcp_bpf_prots))
699 		newsk->sk_prot = sk->sk_prot_creator;
700 }
701 #endif /* CONFIG_BPF_SYSCALL */
702