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 bool tcp_bpf_stream_read(const struct sock *sk) 154 { 155 struct sk_psock *psock; 156 bool empty = true; 157 158 rcu_read_lock(); 159 psock = sk_psock(sk); 160 if (likely(psock)) 161 empty = list_empty(&psock->ingress_msg); 162 rcu_read_unlock(); 163 return !empty; 164 } 165 166 static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 167 int nonblock, int flags, int *addr_len) 168 { 169 struct sk_psock *psock; 170 int copied, ret; 171 172 if (unlikely(flags & MSG_ERRQUEUE)) 173 return inet_recv_error(sk, msg, len, addr_len); 174 175 psock = sk_psock_get(sk); 176 if (unlikely(!psock)) 177 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 178 if (!skb_queue_empty(&sk->sk_receive_queue) && 179 sk_psock_queue_empty(psock)) { 180 sk_psock_put(sk, psock); 181 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 182 } 183 lock_sock(sk); 184 msg_bytes_ready: 185 copied = sk_msg_recvmsg(sk, psock, msg, len, flags); 186 if (!copied) { 187 long timeo; 188 int data; 189 190 timeo = sock_rcvtimeo(sk, nonblock); 191 data = sk_msg_wait_data(sk, psock, timeo); 192 if (data) { 193 if (!sk_psock_queue_empty(psock)) 194 goto msg_bytes_ready; 195 release_sock(sk); 196 sk_psock_put(sk, psock); 197 return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); 198 } 199 copied = -EAGAIN; 200 } 201 ret = copied; 202 release_sock(sk); 203 sk_psock_put(sk, psock); 204 return ret; 205 } 206 207 static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, 208 struct sk_msg *msg, int *copied, int flags) 209 { 210 bool cork = false, enospc = sk_msg_full(msg); 211 struct sock *sk_redir; 212 u32 tosend, delta = 0; 213 int ret; 214 215 more_data: 216 if (psock->eval == __SK_NONE) { 217 /* Track delta in msg size to add/subtract it on SK_DROP from 218 * returned to user copied size. This ensures user doesn't 219 * get a positive return code with msg_cut_data and SK_DROP 220 * verdict. 221 */ 222 delta = msg->sg.size; 223 psock->eval = sk_psock_msg_verdict(sk, psock, msg); 224 delta -= msg->sg.size; 225 } 226 227 if (msg->cork_bytes && 228 msg->cork_bytes > msg->sg.size && !enospc) { 229 psock->cork_bytes = msg->cork_bytes - msg->sg.size; 230 if (!psock->cork) { 231 psock->cork = kzalloc(sizeof(*psock->cork), 232 GFP_ATOMIC | __GFP_NOWARN); 233 if (!psock->cork) 234 return -ENOMEM; 235 } 236 memcpy(psock->cork, msg, sizeof(*msg)); 237 return 0; 238 } 239 240 tosend = msg->sg.size; 241 if (psock->apply_bytes && psock->apply_bytes < tosend) 242 tosend = psock->apply_bytes; 243 244 switch (psock->eval) { 245 case __SK_PASS: 246 ret = tcp_bpf_push(sk, msg, tosend, flags, true); 247 if (unlikely(ret)) { 248 *copied -= sk_msg_free(sk, msg); 249 break; 250 } 251 sk_msg_apply_bytes(psock, tosend); 252 break; 253 case __SK_REDIRECT: 254 sk_redir = psock->sk_redir; 255 sk_msg_apply_bytes(psock, tosend); 256 if (psock->cork) { 257 cork = true; 258 psock->cork = NULL; 259 } 260 sk_msg_return(sk, msg, tosend); 261 release_sock(sk); 262 ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags); 263 lock_sock(sk); 264 if (unlikely(ret < 0)) { 265 int free = sk_msg_free_nocharge(sk, msg); 266 267 if (!cork) 268 *copied -= free; 269 } 270 if (cork) { 271 sk_msg_free(sk, msg); 272 kfree(msg); 273 msg = NULL; 274 ret = 0; 275 } 276 break; 277 case __SK_DROP: 278 default: 279 sk_msg_free_partial(sk, msg, tosend); 280 sk_msg_apply_bytes(psock, tosend); 281 *copied -= (tosend + delta); 282 return -EACCES; 283 } 284 285 if (likely(!ret)) { 286 if (!psock->apply_bytes) { 287 psock->eval = __SK_NONE; 288 if (psock->sk_redir) { 289 sock_put(psock->sk_redir); 290 psock->sk_redir = NULL; 291 } 292 } 293 if (msg && 294 msg->sg.data[msg->sg.start].page_link && 295 msg->sg.data[msg->sg.start].length) 296 goto more_data; 297 } 298 return ret; 299 } 300 301 static int tcp_bpf_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) 302 { 303 struct sk_msg tmp, *msg_tx = NULL; 304 int copied = 0, err = 0; 305 struct sk_psock *psock; 306 long timeo; 307 int flags; 308 309 /* Don't let internal do_tcp_sendpages() flags through */ 310 flags = (msg->msg_flags & ~MSG_SENDPAGE_DECRYPTED); 311 flags |= MSG_NO_SHARED_FRAGS; 312 313 psock = sk_psock_get(sk); 314 if (unlikely(!psock)) 315 return tcp_sendmsg(sk, msg, size); 316 317 lock_sock(sk); 318 timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); 319 while (msg_data_left(msg)) { 320 bool enospc = false; 321 u32 copy, osize; 322 323 if (sk->sk_err) { 324 err = -sk->sk_err; 325 goto out_err; 326 } 327 328 copy = msg_data_left(msg); 329 if (!sk_stream_memory_free(sk)) 330 goto wait_for_sndbuf; 331 if (psock->cork) { 332 msg_tx = psock->cork; 333 } else { 334 msg_tx = &tmp; 335 sk_msg_init(msg_tx); 336 } 337 338 osize = msg_tx->sg.size; 339 err = sk_msg_alloc(sk, msg_tx, msg_tx->sg.size + copy, msg_tx->sg.end - 1); 340 if (err) { 341 if (err != -ENOSPC) 342 goto wait_for_memory; 343 enospc = true; 344 copy = msg_tx->sg.size - osize; 345 } 346 347 err = sk_msg_memcopy_from_iter(sk, &msg->msg_iter, msg_tx, 348 copy); 349 if (err < 0) { 350 sk_msg_trim(sk, msg_tx, osize); 351 goto out_err; 352 } 353 354 copied += copy; 355 if (psock->cork_bytes) { 356 if (size > psock->cork_bytes) 357 psock->cork_bytes = 0; 358 else 359 psock->cork_bytes -= size; 360 if (psock->cork_bytes && !enospc) 361 goto out_err; 362 /* All cork bytes are accounted, rerun the prog. */ 363 psock->eval = __SK_NONE; 364 psock->cork_bytes = 0; 365 } 366 367 err = tcp_bpf_send_verdict(sk, psock, msg_tx, &copied, flags); 368 if (unlikely(err < 0)) 369 goto out_err; 370 continue; 371 wait_for_sndbuf: 372 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 373 wait_for_memory: 374 err = sk_stream_wait_memory(sk, &timeo); 375 if (err) { 376 if (msg_tx && msg_tx != psock->cork) 377 sk_msg_free(sk, msg_tx); 378 goto out_err; 379 } 380 } 381 out_err: 382 if (err < 0) 383 err = sk_stream_error(sk, msg->msg_flags, err); 384 release_sock(sk); 385 sk_psock_put(sk, psock); 386 return copied ? copied : err; 387 } 388 389 static int tcp_bpf_sendpage(struct sock *sk, struct page *page, int offset, 390 size_t size, int flags) 391 { 392 struct sk_msg tmp, *msg = NULL; 393 int err = 0, copied = 0; 394 struct sk_psock *psock; 395 bool enospc = false; 396 397 psock = sk_psock_get(sk); 398 if (unlikely(!psock)) 399 return tcp_sendpage(sk, page, offset, size, flags); 400 401 lock_sock(sk); 402 if (psock->cork) { 403 msg = psock->cork; 404 } else { 405 msg = &tmp; 406 sk_msg_init(msg); 407 } 408 409 /* Catch case where ring is full and sendpage is stalled. */ 410 if (unlikely(sk_msg_full(msg))) 411 goto out_err; 412 413 sk_msg_page_add(msg, page, size, offset); 414 sk_mem_charge(sk, size); 415 copied = size; 416 if (sk_msg_full(msg)) 417 enospc = true; 418 if (psock->cork_bytes) { 419 if (size > psock->cork_bytes) 420 psock->cork_bytes = 0; 421 else 422 psock->cork_bytes -= size; 423 if (psock->cork_bytes && !enospc) 424 goto out_err; 425 /* All cork bytes are accounted, rerun the prog. */ 426 psock->eval = __SK_NONE; 427 psock->cork_bytes = 0; 428 } 429 430 err = tcp_bpf_send_verdict(sk, psock, msg, &copied, flags); 431 out_err: 432 release_sock(sk); 433 sk_psock_put(sk, psock); 434 return copied ? copied : err; 435 } 436 437 enum { 438 TCP_BPF_IPV4, 439 TCP_BPF_IPV6, 440 TCP_BPF_NUM_PROTS, 441 }; 442 443 enum { 444 TCP_BPF_BASE, 445 TCP_BPF_TX, 446 TCP_BPF_NUM_CFGS, 447 }; 448 449 static struct proto *tcpv6_prot_saved __read_mostly; 450 static DEFINE_SPINLOCK(tcpv6_prot_lock); 451 static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS]; 452 453 static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS], 454 struct proto *base) 455 { 456 prot[TCP_BPF_BASE] = *base; 457 prot[TCP_BPF_BASE].unhash = sock_map_unhash; 458 prot[TCP_BPF_BASE].close = sock_map_close; 459 prot[TCP_BPF_BASE].recvmsg = tcp_bpf_recvmsg; 460 prot[TCP_BPF_BASE].stream_memory_read = tcp_bpf_stream_read; 461 462 prot[TCP_BPF_TX] = prot[TCP_BPF_BASE]; 463 prot[TCP_BPF_TX].sendmsg = tcp_bpf_sendmsg; 464 prot[TCP_BPF_TX].sendpage = tcp_bpf_sendpage; 465 } 466 467 static void tcp_bpf_check_v6_needs_rebuild(struct proto *ops) 468 { 469 if (unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) { 470 spin_lock_bh(&tcpv6_prot_lock); 471 if (likely(ops != tcpv6_prot_saved)) { 472 tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops); 473 smp_store_release(&tcpv6_prot_saved, ops); 474 } 475 spin_unlock_bh(&tcpv6_prot_lock); 476 } 477 } 478 479 static int __init tcp_bpf_v4_build_proto(void) 480 { 481 tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot); 482 return 0; 483 } 484 core_initcall(tcp_bpf_v4_build_proto); 485 486 static int tcp_bpf_assert_proto_ops(struct proto *ops) 487 { 488 /* In order to avoid retpoline, we make assumptions when we call 489 * into ops if e.g. a psock is not present. Make sure they are 490 * indeed valid assumptions. 491 */ 492 return ops->recvmsg == tcp_recvmsg && 493 ops->sendmsg == tcp_sendmsg && 494 ops->sendpage == tcp_sendpage ? 0 : -ENOTSUPP; 495 } 496 497 int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore) 498 { 499 int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4; 500 int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE; 501 502 if (restore) { 503 if (inet_csk_has_ulp(sk)) { 504 /* TLS does not have an unhash proto in SW cases, 505 * but we need to ensure we stop using the sock_map 506 * unhash routine because the associated psock is being 507 * removed. So use the original unhash handler. 508 */ 509 WRITE_ONCE(sk->sk_prot->unhash, psock->saved_unhash); 510 tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space); 511 } else { 512 sk->sk_write_space = psock->saved_write_space; 513 /* Pairs with lockless read in sk_clone_lock() */ 514 WRITE_ONCE(sk->sk_prot, psock->sk_proto); 515 } 516 return 0; 517 } 518 519 if (inet_csk_has_ulp(sk)) 520 return -EINVAL; 521 522 if (sk->sk_family == AF_INET6) { 523 if (tcp_bpf_assert_proto_ops(psock->sk_proto)) 524 return -EINVAL; 525 526 tcp_bpf_check_v6_needs_rebuild(psock->sk_proto); 527 } 528 529 /* Pairs with lockless read in sk_clone_lock() */ 530 WRITE_ONCE(sk->sk_prot, &tcp_bpf_prots[family][config]); 531 return 0; 532 } 533 EXPORT_SYMBOL_GPL(tcp_bpf_update_proto); 534 535 /* If a child got cloned from a listening socket that had tcp_bpf 536 * protocol callbacks installed, we need to restore the callbacks to 537 * the default ones because the child does not inherit the psock state 538 * that tcp_bpf callbacks expect. 539 */ 540 void tcp_bpf_clone(const struct sock *sk, struct sock *newsk) 541 { 542 int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4; 543 struct proto *prot = newsk->sk_prot; 544 545 if (prot == &tcp_bpf_prots[family][TCP_BPF_BASE]) 546 newsk->sk_prot = sk->sk_prot_creator; 547 } 548 #endif /* CONFIG_BPF_SYSCALL */ 549