net/ipv4/tcp_bpf.c

   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 static bool tcp_bpf_stream_read(const struct sock *sk)
  14 {
  15         struct sk_psock *psock;
  16         bool empty = true;
  17
  18         rcu_read_lock();
  19         psock = sk_psock(sk);
  20         if (likely(psock))
  21                 empty = list_empty(&psock->ingress_msg);
  22         rcu_read_unlock();
  23         return !empty;
  24 }
  25
  26 static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock,
  27                              int flags, long timeo, int *err)
  28 {
  29         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  30         int ret = 0;
  31
  32         if (!timeo)
  33                 return ret;
  34
  35         add_wait_queue(sk_sleep(sk), &wait);
  36         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
  37         ret = sk_wait_event(sk, &timeo,
  38                             !list_empty(&psock->ingress_msg) ||
  39                             !skb_queue_empty(&sk->sk_receive_queue), &wait);
  40         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
  41         remove_wait_queue(sk_sleep(sk), &wait);
  42         return ret;
  43 }
  44
  45 int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
  46                       struct msghdr *msg, int len, int flags)
  47 {
  48         struct iov_iter *iter = &msg->msg_iter;
  49         int peek = flags & MSG_PEEK;
  50         int i, ret, copied = 0;
  51         struct sk_msg *msg_rx;
  52
  53         msg_rx = list_first_entry_or_null(&psock->ingress_msg,
  54                                           struct sk_msg, list);
  55
  56         while (copied != len) {
  57                 struct scatterlist *sge;
  58
  59                 if (unlikely(!msg_rx))
  60                         break;
  61
  62                 i = msg_rx->sg.start;
  63                 do {
  64                         struct page *page;
  65                         int copy;
  66
  67                         sge = sk_msg_elem(msg_rx, i);
  68                         copy = sge->length;
  69                         page = sg_page(sge);
  70                         if (copied + copy > len)
  71                                 copy = len - copied;
  72                         ret = copy_page_to_iter(page, sge->offset, copy, iter);
  73                         if (ret != copy) {
  74                                 msg_rx->sg.start = i;
  75                                 return -EFAULT;
  76                         }
  77
  78                         copied += copy;
  79                         if (likely(!peek)) {
  80                                 sge->offset += copy;
  81                                 sge->length -= copy;
  82                                 sk_mem_uncharge(sk, copy);
  83                                 msg_rx->sg.size -= copy;
  84
  85                                 if (!sge->length) {
  86                                         sk_msg_iter_var_next(i);
  87                                         if (!msg_rx->skb)
  88                                                 put_page(page);
  89                                 }
  90                         } else {
  91                                 sk_msg_iter_var_next(i);
  92                         }
  93
  94                         if (copied == len)
  95                                 break;
  96                 } while (i != msg_rx->sg.end);
  97
  98                 if (unlikely(peek)) {
  99                         msg_rx = list_next_entry(msg_rx, list);
 100                         continue;
 101                 }
 102
 103                 msg_rx->sg.start = i;
 104                 if (!sge->length && msg_rx->sg.start == msg_rx->sg.end) {
 105                         list_del(&msg_rx->list);
 106                         if (msg_rx->skb)
 107                                 consume_skb(msg_rx->skb);
 108                         kfree(msg_rx);
 109                 }
 110                 msg_rx = list_first_entry_or_null(&psock->ingress_msg,
 111                                                   struct sk_msg, list);
 112         }
 113
 114         return copied;
 115 }
 116 EXPORT_SYMBOL_GPL(__tcp_bpf_recvmsg);
 117
 118 int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 119                     int nonblock, int flags, int *addr_len)
 120 {
 121         struct sk_psock *psock;
 122         int copied, ret;
 123
 124         if (unlikely(flags & MSG_ERRQUEUE))
 125                 return inet_recv_error(sk, msg, len, addr_len);
 126         if (!skb_queue_empty(&sk->sk_receive_queue))
 127                 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
 128
 129         psock = sk_psock_get(sk);
 130         if (unlikely(!psock))
 131                 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
 132         lock_sock(sk);
 133 msg_bytes_ready:
 134         copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
 135         if (!copied) {
 136                 int data, err = 0;
 137                 long timeo;
 138
 139                 timeo = sock_rcvtimeo(sk, nonblock);
 140                 data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err);
 141                 if (data) {
 142                         if (skb_queue_empty(&sk->sk_receive_queue))
 143                                 goto msg_bytes_ready;
 144                         release_sock(sk);
 145                         sk_psock_put(sk, psock);
 146                         return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
 147                 }
 148                 if (err) {
 149                         ret = err;
 150                         goto out;
 151                 }
 152                 copied = -EAGAIN;
 153         }
 154         ret = copied;
 155 out:
 156         release_sock(sk);
 157         sk_psock_put(sk, psock);
 158         return ret;
 159 }
 160
 161 static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
 162                            struct sk_msg *msg, u32 apply_bytes, int flags)
 163 {
 164         bool apply = apply_bytes;
 165         struct scatterlist *sge;
 166         u32 size, copied = 0;
 167         struct sk_msg *tmp;
 168         int i, ret = 0;
 169
 170         tmp = kzalloc(sizeof(*tmp), __GFP_NOWARN | GFP_KERNEL);
 171         if (unlikely(!tmp))
 172                 return -ENOMEM;
 173
 174         lock_sock(sk);
 175         tmp->sg.start = msg->sg.start;
 176         i = msg->sg.start;
 177         do {
 178                 sge = sk_msg_elem(msg, i);
 179                 size = (apply && apply_bytes < sge->length) ?
 180                         apply_bytes : sge->length;
 181                 if (!sk_wmem_schedule(sk, size)) {
 182                         if (!copied)
 183                                 ret = -ENOMEM;
 184                         break;
 185                 }
 186
 187                 sk_mem_charge(sk, size);
 188                 sk_msg_xfer(tmp, msg, i, size);
 189                 copied += size;
 190                 if (sge->length)
 191                         get_page(sk_msg_page(tmp, i));
 192                 sk_msg_iter_var_next(i);
 193                 tmp->sg.end = i;
 194                 if (apply) {
 195                         apply_bytes -= size;
 196                         if (!apply_bytes)
 197                                 break;
 198                 }
 199         } while (i != msg->sg.end);
 200
 201         if (!ret) {
 202                 msg->sg.start = i;
 203                 msg->sg.size -= apply_bytes;
 204                 sk_psock_queue_msg(psock, tmp);
 205                 sk_psock_data_ready(sk, psock);
 206         } else {
 207                 sk_msg_free(sk, tmp);
 208                 kfree(tmp);
 209         }
 210
 211         release_sock(sk);
 212         return ret;
 213 }
 214
 215 static int tcp_bpf_push(struct sock *sk, struct sk_msg *msg, u32 apply_bytes,
 216                         int flags, bool uncharge)
 217 {
 218         bool apply = apply_bytes;
 219         struct scatterlist *sge;
 220         struct page *page;
 221         int size, ret = 0;
 222         u32 off;
 223
 224         while (1) {
 225                 bool has_tx_ulp;
 226
 227                 sge = sk_msg_elem(msg, msg->sg.start);
 228                 size = (apply && apply_bytes < sge->length) ?
 229                         apply_bytes : sge->length;
 230                 off  = sge->offset;
 231                 page = sg_page(sge);
 232
 233                 tcp_rate_check_app_limited(sk);
 234 retry:
 235                 has_tx_ulp = tls_sw_has_ctx_tx(sk);
 236                 if (has_tx_ulp) {
 237                         flags |= MSG_SENDPAGE_NOPOLICY;
 238                         ret = kernel_sendpage_locked(sk,
 239                                                      page, off, size, flags);
 240                 } else {
 241                         ret = do_tcp_sendpages(sk, page, off, size, flags);
 242                 }
 243
 244                 if (ret <= 0)
 245                         return ret;
 246                 if (apply)
 247                         apply_bytes -= ret;
 248                 msg->sg.size -= ret;
 249                 sge->offset += ret;
 250                 sge->length -= ret;
 251                 if (uncharge)
 252                         sk_mem_uncharge(sk, ret);
 253                 if (ret != size) {
 254                         size -= ret;
 255                         off  += ret;
 256                         goto retry;
 257                 }
 258                 if (!sge->length) {
 259                         put_page(page);
 260                         sk_msg_iter_next(msg, start);
 261                         sg_init_table(sge, 1);
 262                         if (msg->sg.start == msg->sg.end)
 263                                 break;
 264                 }
 265                 if (apply && !apply_bytes)
 266                         break;
 267         }
 268
 269         return 0;
 270 }
 271
 272 static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
 273                                u32 apply_bytes, int flags, bool uncharge)
 274 {
 275         int ret;
 276
 277         lock_sock(sk);
 278         ret = tcp_bpf_push(sk, msg, apply_bytes, flags, uncharge);
 279         release_sock(sk);
 280         return ret;
 281 }
 282
 283 int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
 284                           u32 bytes, int flags)
 285 {
 286         bool ingress = sk_msg_to_ingress(msg);
 287         struct sk_psock *psock = sk_psock_get(sk);
 288         int ret;
 289
 290         if (unlikely(!psock)) {
 291                 sk_msg_free(sk, msg);
 292                 return 0;
 293         }
 294         ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes, flags) :
 295                         tcp_bpf_push_locked(sk, msg, bytes, flags, false);
 296         sk_psock_put(sk, psock);
 297         return ret;
 298 }
 299 EXPORT_SYMBOL_GPL(tcp_bpf_sendmsg_redir);
 300
 301 static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
 302                                 struct sk_msg *msg, int *copied, int flags)
 303 {
 304         bool cork = false, enospc = msg->sg.start == msg->sg.end;
 305         struct sock *sk_redir;
 306         u32 tosend, delta = 0;
 307         int ret;
 308
 309 more_data:
 310         if (psock->eval == __SK_NONE) {
 311                 /* Track delta in msg size to add/subtract it on SK_DROP from
 312                  * returned to user copied size. This ensures user doesn't
 313                  * get a positive return code with msg_cut_data and SK_DROP
 314                  * verdict.
 315                  */
 316                 delta = msg->sg.size;
 317                 psock->eval = sk_psock_msg_verdict(sk, psock, msg);
 318                 if (msg->sg.size < delta)
 319                         delta -= msg->sg.size;
 320                 else
 321                         delta = 0;
 322         }
 323
 324         if (msg->cork_bytes &&
 325             msg->cork_bytes > msg->sg.size && !enospc) {
 326                 psock->cork_bytes = msg->cork_bytes - msg->sg.size;
 327                 if (!psock->cork) {
 328                         psock->cork = kzalloc(sizeof(*psock->cork),
 329                                               GFP_ATOMIC | __GFP_NOWARN);
 330                         if (!psock->cork)
 331                                 return -ENOMEM;
 332                 }
 333                 memcpy(psock->cork, msg, sizeof(*msg));
 334                 return 0;
 335         }
 336
 337         tosend = msg->sg.size;
 338         if (psock->apply_bytes && psock->apply_bytes < tosend)
 339                 tosend = psock->apply_bytes;
 340
 341         switch (psock->eval) {
 342         case __SK_PASS:
 343                 ret = tcp_bpf_push(sk, msg, tosend, flags, true);
 344                 if (unlikely(ret)) {
 345                         *copied -= sk_msg_free(sk, msg);
 346                         break;
 347                 }
 348                 sk_msg_apply_bytes(psock, tosend);
 349                 break;
 350         case __SK_REDIRECT:
 351                 sk_redir = psock->sk_redir;
 352                 sk_msg_apply_bytes(psock, tosend);
 353                 if (psock->cork) {
 354                         cork = true;
 355                         psock->cork = NULL;
 356                 }
 357                 sk_msg_return(sk, msg, tosend);
 358                 release_sock(sk);
 359                 ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags);
 360                 lock_sock(sk);
 361                 if (unlikely(ret < 0)) {
 362                         int free = sk_msg_free_nocharge(sk, msg);
 363
 364                         if (!cork)
 365                                 *copied -= free;
 366                 }
 367                 if (cork) {
 368                         sk_msg_free(sk, msg);
 369                         kfree(msg);
 370                         msg = NULL;
 371                         ret = 0;
 372                 }
 373                 break;
 374         case __SK_DROP:
 375         default:
 376                 sk_msg_free_partial(sk, msg, tosend);
 377                 sk_msg_apply_bytes(psock, tosend);
 378                 *copied -= (tosend + delta);
 379                 return -EACCES;
 380         }
 381
 382         if (likely(!ret)) {
 383                 if (!psock->apply_bytes) {
 384                         psock->eval =  __SK_NONE;
 385                         if (psock->sk_redir) {
 386                                 sock_put(psock->sk_redir);
 387                                 psock->sk_redir = NULL;
 388                         }
 389                 }
 390                 if (msg &&
 391                     msg->sg.data[msg->sg.start].page_link &&
 392                     msg->sg.data[msg->sg.start].length)
 393                         goto more_data;
 394         }
 395         return ret;
 396 }
 397
 398 static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 399 {
 400         struct sk_msg tmp, *msg_tx = NULL;
 401         int flags = msg->msg_flags | MSG_NO_SHARED_FRAGS;
 402         int copied = 0, err = 0;
 403         struct sk_psock *psock;
 404         long timeo;
 405
 406         psock = sk_psock_get(sk);
 407         if (unlikely(!psock))
 408                 return tcp_sendmsg(sk, msg, size);
 409
 410         lock_sock(sk);
 411         timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 412         while (msg_data_left(msg)) {
 413                 bool enospc = false;
 414                 u32 copy, osize;
 415
 416                 if (sk->sk_err) {
 417                         err = -sk->sk_err;
 418                         goto out_err;
 419                 }
 420
 421                 copy = msg_data_left(msg);
 422                 if (!sk_stream_memory_free(sk))
 423                         goto wait_for_sndbuf;
 424                 if (psock->cork) {
 425                         msg_tx = psock->cork;
 426                 } else {
 427                         msg_tx = &tmp;
 428                         sk_msg_init(msg_tx);
 429                 }
 430
 431                 osize = msg_tx->sg.size;
 432                 err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1);
 433                 if (err) {
 434                         if (err != -ENOSPC)
 435                                 goto wait_for_memory;
 436                         enospc = true;
 437                         copy = msg_tx->sg.size - osize;
 438                 }
 439
 440                 err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx,
 441                                                copy);
 442                 if (err < 0) {
 443                         sk_msg_trim(sk, msg_tx, osize);
 444                         goto out_err;
 445                 }
 446
 447                 copied += copy;
 448                 if (psock->cork_bytes) {
 449                         if (size > psock->cork_bytes)
 450                                 psock->cork_bytes = 0;
 451                         else
 452                                 psock->cork_bytes -= size;
 453                         if (psock->cork_bytes && !enospc)
 454                                 goto out_err;
 455                         /* All cork bytes are accounted, rerun the prog. */
 456                         psock->eval = __SK_NONE;
 457                         psock->cork_bytes = 0;
 458                 }
 459
 460                 err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags);
 461                 if (unlikely(err < 0))
 462                         goto out_err;
 463                 continue;
 464 wait_for_sndbuf:
 465                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 466 wait_for_memory:
 467                 err = sk_stream_wait_memory(sk, &timeo);
 468                 if (err) {
 469                         if (msg_tx && msg_tx != psock->cork)
 470                                 sk_msg_free(sk, msg_tx);
 471                         goto out_err;
 472                 }
 473         }
 474 out_err:
 475         if (err < 0)
 476                 err = sk_stream_error(sk, msg->msg_flags, err);
 477         release_sock(sk);
 478         sk_psock_put(sk, psock);
 479         return copied ? copied : err;
 480 }
 481
 482 static int tcp_bpf_sendpage(struct sock *sk, struct page *page, int offset,
 483                             size_t size, int flags)
 484 {
 485         struct sk_msg tmp, *msg = NULL;
 486         int err = 0, copied = 0;
 487         struct sk_psock *psock;
 488         bool enospc = false;
 489
 490         psock = sk_psock_get(sk);
 491         if (unlikely(!psock))
 492                 return tcp_sendpage(sk, page, offset, size, flags);
 493
 494         lock_sock(sk);
 495         if (psock->cork) {
 496                 msg = psock->cork;
 497         } else {
 498                 msg = &tmp;
 499                 sk_msg_init(msg);
 500         }
 501
 502         /* Catch case where ring is full and sendpage is stalled. */
 503         if (unlikely(sk_msg_full(msg)))
 504                 goto out_err;
 505
 506         sk_msg_page_add(msg, page, size, offset);
 507         sk_mem_charge(sk, size);
 508         copied = size;
 509         if (sk_msg_full(msg))
 510                 enospc = true;
 511         if (psock->cork_bytes) {
 512                 if (size > psock->cork_bytes)
 513                         psock->cork_bytes = 0;
 514                 else
 515                         psock->cork_bytes -= size;
 516                 if (psock->cork_bytes && !enospc)
 517                         goto out_err;
 518                 /* All cork bytes are accounted, rerun the prog. */
 519                 psock->eval = __SK_NONE;
 520                 psock->cork_bytes = 0;
 521         }
 522
 523         err = tcp_bpf_send_verdict(sk, psock, msg, &copied, flags);
 524 out_err:
 525         release_sock(sk);
 526         sk_psock_put(sk, psock);
 527         return copied ? copied : err;
 528 }
 529
 530 static void tcp_bpf_remove(struct sock *sk, struct sk_psock *psock)
 531 {
 532         struct sk_psock_link *link;
 533
 534         while ((link = sk_psock_link_pop(psock))) {
 535                 sk_psock_unlink(sk, link);
 536                 sk_psock_free_link(link);
 537         }
 538 }
 539
 540 static void tcp_bpf_unhash(struct sock *sk)
 541 {
 542         void (*saved_unhash)(struct sock *sk);
 543         struct sk_psock *psock;
 544
 545         rcu_read_lock();
 546         psock = sk_psock(sk);
 547         if (unlikely(!psock)) {
 548                 rcu_read_unlock();
 549                 if (sk->sk_prot->unhash)
 550                         sk->sk_prot->unhash(sk);
 551                 return;
 552         }
 553
 554         saved_unhash = psock->saved_unhash;
 555         tcp_bpf_remove(sk, psock);
 556         rcu_read_unlock();
 557         saved_unhash(sk);
 558 }
 559
 560 static void tcp_bpf_close(struct sock *sk, long timeout)
 561 {
 562         void (*saved_close)(struct sock *sk, long timeout);
 563         struct sk_psock *psock;
 564
 565         lock_sock(sk);
 566         rcu_read_lock();
 567         psock = sk_psock(sk);
 568         if (unlikely(!psock)) {
 569                 rcu_read_unlock();
 570                 release_sock(sk);
 571                 return sk->sk_prot->close(sk, timeout);
 572         }
 573
 574         saved_close = psock->saved_close;
 575         tcp_bpf_remove(sk, psock);
 576         rcu_read_unlock();
 577         release_sock(sk);
 578         saved_close(sk, timeout);
 579 }
 580
 581 enum {
 582         TCP_BPF_IPV4,
 583         TCP_BPF_IPV6,
 584         TCP_BPF_NUM_PROTS,
 585 };
 586
 587 enum {
 588         TCP_BPF_BASE,
 589         TCP_BPF_TX,
 590         TCP_BPF_NUM_CFGS,
 591 };
 592
 593 static struct proto *tcpv6_prot_saved __read_mostly;
 594 static DEFINE_SPINLOCK(tcpv6_prot_lock);
 595 static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
 596
 597 static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
 598                                    struct proto *base)
 599 {
 600         prot[TCP_BPF_BASE]                      = *base;
 601         prot[TCP_BPF_BASE].unhash               = tcp_bpf_unhash;
 602         prot[TCP_BPF_BASE].close                = tcp_bpf_close;
 603         prot[TCP_BPF_BASE].recvmsg              = tcp_bpf_recvmsg;
 604         prot[TCP_BPF_BASE].stream_memory_read   = tcp_bpf_stream_read;
 605
 606         prot[TCP_BPF_TX]                        = prot[TCP_BPF_BASE];
 607         prot[TCP_BPF_TX].sendmsg                = tcp_bpf_sendmsg;
 608         prot[TCP_BPF_TX].sendpage               = tcp_bpf_sendpage;
 609 }
 610
 611 static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
 612 {
 613         if (sk->sk_family == AF_INET6 &&
 614             unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
 615                 spin_lock_bh(&tcpv6_prot_lock);
 616                 if (likely(ops != tcpv6_prot_saved)) {
 617                         tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
 618                         smp_store_release(&tcpv6_prot_saved, ops);
 619                 }
 620                 spin_unlock_bh(&tcpv6_prot_lock);
 621         }
 622 }
 623
 624 static int __init tcp_bpf_v4_build_proto(void)
 625 {
 626         tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
 627         return 0;
 628 }
 629 core_initcall(tcp_bpf_v4_build_proto);
 630
 631 static void tcp_bpf_update_sk_prot(struct sock *sk, struct sk_psock *psock)
 632 {
 633         int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
 634         int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
 635
 636         sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config]);
 637 }
 638
 639 static void tcp_bpf_reinit_sk_prot(struct sock *sk, struct sk_psock *psock)
 640 {
 641         int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
 642         int config = psock->progs.msg_parser   ? TCP_BPF_TX   : TCP_BPF_BASE;
 643
 644         /* Reinit occurs when program types change e.g. TCP_BPF_TX is removed
 645          * or added requiring sk_prot hook updates. We keep original saved
 646          * hooks in this case.
 647          */
 648         sk->sk_prot = &tcp_bpf_prots[family][config];
 649 }
 650
 651 static int tcp_bpf_assert_proto_ops(struct proto *ops)
 652 {
 653         /* In order to avoid retpoline, we make assumptions when we call
 654          * into ops if e.g. a psock is not present. Make sure they are
 655          * indeed valid assumptions.
 656          */
 657         return ops->recvmsg  == tcp_recvmsg &&
 658                ops->sendmsg  == tcp_sendmsg &&
 659                ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP;
 660 }
 661
 662 void tcp_bpf_reinit(struct sock *sk)
 663 {
 664         struct sk_psock *psock;
 665
 666         sock_owned_by_me(sk);
 667
 668         rcu_read_lock();
 669         psock = sk_psock(sk);
 670         tcp_bpf_reinit_sk_prot(sk, psock);
 671         rcu_read_unlock();
 672 }
 673
 674 int tcp_bpf_init(struct sock *sk)
 675 {
 676         struct proto *ops = READ_ONCE(sk->sk_prot);
 677         struct sk_psock *psock;
 678
 679         sock_owned_by_me(sk);
 680
 681         rcu_read_lock();
 682         psock = sk_psock(sk);
 683         if (unlikely(!psock || psock->sk_proto ||
 684                      tcp_bpf_assert_proto_ops(ops))) {
 685                 rcu_read_unlock();
 686                 return -EINVAL;
 687         }
 688         tcp_bpf_check_v6_needs_rebuild(sk, ops);
 689         tcp_bpf_update_sk_prot(sk, psock);
 690         rcu_read_unlock();
 691         return 0;
 692 }