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