1// SPDX-License-Identifier: GPL-2.0
   2/* Multipath TCP
   3 *
   4 * Copyright (c) 2017 - 2019, Intel Corporation.
   5 */
   6
   7#define pr_fmt(fmt) "MPTCP: " fmt
   8
   9#include <linux/kernel.h>
  10#include <linux/module.h>
  11#include <linux/netdevice.h>
 
  12#include <crypto/sha2.h>
  13#include <crypto/utils.h>
  14#include <net/sock.h>
  15#include <net/inet_common.h>
  16#include <net/inet_hashtables.h>
  17#include <net/protocol.h>
 
  18#if IS_ENABLED(CONFIG_MPTCP_IPV6)
  19#include <net/ip6_route.h>
  20#include <net/transp_v6.h>
  21#endif
  22#include <net/mptcp.h>
  23
  24#include "protocol.h"
  25#include "mib.h"
  26
  27#include <trace/events/mptcp.h>
  28#include <trace/events/sock.h>
  29
  30static void mptcp_subflow_ops_undo_override(struct sock *ssk);
  31
  32static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
  33				  enum linux_mptcp_mib_field field)
  34{
  35	MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
  36}
  37
  38static void subflow_req_destructor(struct request_sock *req)
  39{
  40	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  41
  42	pr_debug("subflow_req=%p\n", subflow_req);
  43
  44	if (subflow_req->msk)
  45		sock_put((struct sock *)subflow_req->msk);
  46
  47	mptcp_token_destroy_request(req);
  48}
  49
  50static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
  51				  void *hmac)
  52{
  53	u8 msg[8];
  54
  55	put_unaligned_be32(nonce1, &msg[0]);
  56	put_unaligned_be32(nonce2, &msg[4]);
  57
  58	mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
  59}
  60
  61static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
  62{
  63	return mptcp_is_fully_established((void *)msk) &&
  64		((mptcp_pm_is_userspace(msk) &&
  65		  mptcp_userspace_pm_active(msk)) ||
  66		 READ_ONCE(msk->pm.accept_subflow));
  67}
  68
  69/* validate received token and create truncated hmac and nonce for SYN-ACK */
  70static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
  71{
  72	struct mptcp_sock *msk = subflow_req->msk;
  73	u8 hmac[SHA256_DIGEST_SIZE];
  74
  75	get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
  76
  77	subflow_generate_hmac(READ_ONCE(msk->local_key),
  78			      READ_ONCE(msk->remote_key),
  79			      subflow_req->local_nonce,
  80			      subflow_req->remote_nonce, hmac);
  81
  82	subflow_req->thmac = get_unaligned_be64(hmac);
  83}
  84
  85static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
  86{
  87	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
  88	struct mptcp_sock *msk;
  89	int local_id;
  90
  91	msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
  92	if (!msk) {
  93		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
  94		return NULL;
  95	}
  96
  97	local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
  98	if (local_id < 0) {
  99		sock_put((struct sock *)msk);
 100		return NULL;
 101	}
 102	subflow_req->local_id = local_id;
 103	subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req);
 104
 105	return msk;
 106}
 107
 108static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
 109{
 110	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 111
 112	subflow_req->mp_capable = 0;
 113	subflow_req->mp_join = 0;
 114	subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
 115	subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
 116	subflow_req->msk = NULL;
 117	mptcp_token_init_request(req);
 118}
 119
 120static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
 121{
 122	return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
 123}
 124
 125static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
 126{
 127	struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 128
 129	if (mpext) {
 130		memset(mpext, 0, sizeof(*mpext));
 131		mpext->reset_reason = reason;
 132	}
 133}
 134
 135static int subflow_reset_req_endp(struct request_sock *req, struct sk_buff *skb)
 136{
 137	SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEENDPATTEMPT);
 138	subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 139	return -EPERM;
 140}
 141
 142/* Init mptcp request socket.
 143 *
 144 * Returns an error code if a JOIN has failed and a TCP reset
 145 * should be sent.
 146 */
 147static int subflow_check_req(struct request_sock *req,
 148			     const struct sock *sk_listener,
 149			     struct sk_buff *skb)
 150{
 151	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 152	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 153	struct mptcp_options_received mp_opt;
 154	bool opt_mp_capable, opt_mp_join;
 155
 156	pr_debug("subflow_req=%p, listener=%p\n", subflow_req, listener);
 157
 158#ifdef CONFIG_TCP_MD5SIG
 159	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
 160	 * TCP option space.
 161	 */
 162	if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) {
 163		subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 164		return -EINVAL;
 165	}
 166#endif
 167
 168	mptcp_get_options(skb, &mp_opt);
 169
 170	opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
 171	opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
 172	if (opt_mp_capable) {
 173		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
 174
 175		if (unlikely(listener->pm_listener))
 176			return subflow_reset_req_endp(req, skb);
 177		if (opt_mp_join)
 178			return 0;
 179	} else if (opt_mp_join) {
 180		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
 181
 182		if (mp_opt.backup)
 183			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX);
 184	} else if (unlikely(listener->pm_listener)) {
 185		return subflow_reset_req_endp(req, skb);
 186	}
 187
 188	if (opt_mp_capable && listener->request_mptcp) {
 189		int err, retries = MPTCP_TOKEN_MAX_RETRIES;
 190
 191		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 192again:
 193		do {
 194			get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
 195		} while (subflow_req->local_key == 0);
 196
 197		if (unlikely(req->syncookie)) {
 198			mptcp_crypto_key_sha(subflow_req->local_key,
 199					     &subflow_req->token,
 200					     &subflow_req->idsn);
 201			if (mptcp_token_exists(subflow_req->token)) {
 202				if (retries-- > 0)
 203					goto again;
 204				SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 205			} else {
 206				subflow_req->mp_capable = 1;
 207			}
 208			return 0;
 209		}
 210
 211		err = mptcp_token_new_request(req);
 212		if (err == 0)
 213			subflow_req->mp_capable = 1;
 214		else if (retries-- > 0)
 215			goto again;
 216		else
 217			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
 218
 219	} else if (opt_mp_join && listener->request_mptcp) {
 220		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
 221		subflow_req->mp_join = 1;
 222		subflow_req->backup = mp_opt.backup;
 223		subflow_req->remote_id = mp_opt.join_id;
 224		subflow_req->token = mp_opt.token;
 225		subflow_req->remote_nonce = mp_opt.nonce;
 226		subflow_req->msk = subflow_token_join_request(req);
 227
 228		/* Can't fall back to TCP in this case. */
 229		if (!subflow_req->msk) {
 230			subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 231			return -EPERM;
 232		}
 233
 234		if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
 235			pr_debug("syn inet_sport=%d %d\n",
 236				 ntohs(inet_sk(sk_listener)->inet_sport),
 237				 ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
 238			if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
 239				SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
 240				subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 241				return -EPERM;
 242			}
 243			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
 244		}
 245
 246		subflow_req_create_thmac(subflow_req);
 247
 248		if (unlikely(req->syncookie)) {
 249			if (!mptcp_can_accept_new_subflow(subflow_req->msk)) {
 250				subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 
 251				return -EPERM;
 252			}
 253
 254			subflow_init_req_cookie_join_save(subflow_req, skb);
 255		}
 256
 257		pr_debug("token=%u, remote_nonce=%u msk=%p\n", subflow_req->token,
 258			 subflow_req->remote_nonce, subflow_req->msk);
 259	}
 260
 261	return 0;
 262}
 263
 264int mptcp_subflow_init_cookie_req(struct request_sock *req,
 265				  const struct sock *sk_listener,
 266				  struct sk_buff *skb)
 267{
 268	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 269	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 270	struct mptcp_options_received mp_opt;
 271	bool opt_mp_capable, opt_mp_join;
 272	int err;
 273
 274	subflow_init_req(req, sk_listener);
 275	mptcp_get_options(skb, &mp_opt);
 276
 277	opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
 278	opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
 279	if (opt_mp_capable && opt_mp_join)
 280		return -EINVAL;
 281
 282	if (opt_mp_capable && listener->request_mptcp) {
 283		if (mp_opt.sndr_key == 0)
 284			return -EINVAL;
 285
 286		subflow_req->local_key = mp_opt.rcvr_key;
 287		err = mptcp_token_new_request(req);
 288		if (err)
 289			return err;
 290
 291		subflow_req->mp_capable = 1;
 292		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 293	} else if (opt_mp_join && listener->request_mptcp) {
 294		if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
 295			return -EINVAL;
 296
 297		subflow_req->mp_join = 1;
 298		subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
 299	}
 300
 301	return 0;
 302}
 303EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
 304
 305static enum sk_rst_reason mptcp_get_rst_reason(const struct sk_buff *skb)
 306{
 307	const struct mptcp_ext *mpext = mptcp_get_ext(skb);
 308
 309	if (!mpext)
 310		return SK_RST_REASON_NOT_SPECIFIED;
 311
 312	return sk_rst_convert_mptcp_reason(mpext->reset_reason);
 313}
 314
 315static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 316					      struct sk_buff *skb,
 317					      struct flowi *fl,
 318					      struct request_sock *req,
 319					      u32 tw_isn)
 320{
 321	struct dst_entry *dst;
 322	int err;
 323
 324	tcp_rsk(req)->is_mptcp = 1;
 325	subflow_init_req(req, sk);
 326
 327	dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req, tw_isn);
 328	if (!dst)
 329		return NULL;
 330
 331	err = subflow_check_req(req, sk, skb);
 332	if (err == 0)
 333		return dst;
 334
 335	dst_release(dst);
 336	if (!req->syncookie)
 337		tcp_request_sock_ops.send_reset(sk, skb,
 338						mptcp_get_rst_reason(skb));
 339	return NULL;
 340}
 341
 342static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
 343				struct tcp_fastopen_cookie *foc,
 344				enum tcp_synack_type synack_type)
 345{
 346	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 347	struct inet_request_sock *ireq = inet_rsk(req);
 348
 349	/* clear tstamp_ok, as needed depending on cookie */
 350	if (foc && foc->len > -1)
 351		ireq->tstamp_ok = 0;
 352
 353	if (synack_type == TCP_SYNACK_FASTOPEN)
 354		mptcp_fastopen_subflow_synack_set_params(subflow, req);
 355}
 356
 357static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
 358				  struct flowi *fl,
 359				  struct request_sock *req,
 360				  struct tcp_fastopen_cookie *foc,
 361				  enum tcp_synack_type synack_type,
 362				  struct sk_buff *syn_skb)
 363{
 364	subflow_prep_synack(sk, req, foc, synack_type);
 365
 366	return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
 367						     synack_type, syn_skb);
 368}
 369
 370#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 371static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 372				  struct flowi *fl,
 373				  struct request_sock *req,
 374				  struct tcp_fastopen_cookie *foc,
 375				  enum tcp_synack_type synack_type,
 376				  struct sk_buff *syn_skb)
 377{
 378	subflow_prep_synack(sk, req, foc, synack_type);
 379
 380	return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
 381						     synack_type, syn_skb);
 382}
 383
 384static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 385					      struct sk_buff *skb,
 386					      struct flowi *fl,
 387					      struct request_sock *req,
 388					      u32 tw_isn)
 389{
 390	struct dst_entry *dst;
 391	int err;
 392
 393	tcp_rsk(req)->is_mptcp = 1;
 394	subflow_init_req(req, sk);
 395
 396	dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req, tw_isn);
 397	if (!dst)
 398		return NULL;
 399
 400	err = subflow_check_req(req, sk, skb);
 401	if (err == 0)
 402		return dst;
 403
 404	dst_release(dst);
 405	if (!req->syncookie)
 406		tcp6_request_sock_ops.send_reset(sk, skb,
 407						 mptcp_get_rst_reason(skb));
 408	return NULL;
 409}
 410#endif
 411
 412/* validate received truncated hmac and create hmac for third ACK */
 413static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
 414{
 415	u8 hmac[SHA256_DIGEST_SIZE];
 416	u64 thmac;
 417
 418	subflow_generate_hmac(subflow->remote_key, subflow->local_key,
 419			      subflow->remote_nonce, subflow->local_nonce,
 420			      hmac);
 421
 422	thmac = get_unaligned_be64(hmac);
 423	pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
 424		 subflow, subflow->token, thmac, subflow->thmac);
 425
 426	return thmac == subflow->thmac;
 427}
 428
 429void mptcp_subflow_reset(struct sock *ssk)
 430{
 431	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 432	struct sock *sk = subflow->conn;
 433
 434	/* mptcp_mp_fail_no_response() can reach here on an already closed
 435	 * socket
 436	 */
 437	if (ssk->sk_state == TCP_CLOSE)
 438		return;
 439
 440	/* must hold: tcp_done() could drop last reference on parent */
 441	sock_hold(sk);
 442
 443	mptcp_send_active_reset_reason(ssk);
 
 444	tcp_done(ssk);
 445	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
 446		mptcp_schedule_work(sk);
 
 447
 448	sock_put(sk);
 449}
 450
 451static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
 452{
 453	return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
 454}
 455
 456void __mptcp_sync_state(struct sock *sk, int state)
 457{
 458	struct mptcp_subflow_context *subflow;
 459	struct mptcp_sock *msk = mptcp_sk(sk);
 460	struct sock *ssk = msk->first;
 461
 462	subflow = mptcp_subflow_ctx(ssk);
 463	__mptcp_propagate_sndbuf(sk, ssk);
 464	if (!msk->rcvspace_init)
 465		mptcp_rcv_space_init(msk, ssk);
 466
 467	if (sk->sk_state == TCP_SYN_SENT) {
 468		/* subflow->idsn is always available is TCP_SYN_SENT state,
 469		 * even for the FASTOPEN scenarios
 470		 */
 471		WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
 472		WRITE_ONCE(msk->snd_nxt, msk->write_seq);
 473		mptcp_set_state(sk, state);
 474		sk->sk_state_change(sk);
 475	}
 476}
 477
 
 
 
 
 
 
 
 
 
 
 478static void subflow_set_remote_key(struct mptcp_sock *msk,
 479				   struct mptcp_subflow_context *subflow,
 480				   const struct mptcp_options_received *mp_opt)
 481{
 482	/* active MPC subflow will reach here multiple times:
 483	 * at subflow_finish_connect() time and at 4th ack time
 484	 */
 485	if (subflow->remote_key_valid)
 486		return;
 487
 488	subflow->remote_key_valid = 1;
 489	subflow->remote_key = mp_opt->sndr_key;
 490	mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
 491	subflow->iasn++;
 492
 493	WRITE_ONCE(msk->remote_key, subflow->remote_key);
 494	WRITE_ONCE(msk->ack_seq, subflow->iasn);
 495	WRITE_ONCE(msk->can_ack, true);
 496	atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
 497}
 498
 499static void mptcp_propagate_state(struct sock *sk, struct sock *ssk,
 500				  struct mptcp_subflow_context *subflow,
 501				  const struct mptcp_options_received *mp_opt)
 502{
 503	struct mptcp_sock *msk = mptcp_sk(sk);
 504
 505	mptcp_data_lock(sk);
 506	if (mp_opt) {
 507		/* Options are available only in the non fallback cases
 508		 * avoid updating rx path fields otherwise
 509		 */
 510		WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
 511		WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);
 512		subflow_set_remote_key(msk, subflow, mp_opt);
 513	}
 514
 515	if (!sock_owned_by_user(sk)) {
 516		__mptcp_sync_state(sk, ssk->sk_state);
 517	} else {
 518		msk->pending_state = ssk->sk_state;
 519		__set_bit(MPTCP_SYNC_STATE, &msk->cb_flags);
 520	}
 521	mptcp_data_unlock(sk);
 522}
 523
 524static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 525{
 526	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 527	struct mptcp_options_received mp_opt;
 528	struct sock *parent = subflow->conn;
 529	struct mptcp_sock *msk;
 530
 531	subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 532
 533	/* be sure no special action on any packet other than syn-ack */
 534	if (subflow->conn_finished)
 535		return;
 536
 537	msk = mptcp_sk(parent);
 
 538	subflow->rel_write_seq = 1;
 539	subflow->conn_finished = 1;
 540	subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
 541	pr_debug("subflow=%p synack seq=%x\n", subflow, subflow->ssn_offset);
 542
 543	mptcp_get_options(skb, &mp_opt);
 544	if (subflow->request_mptcp) {
 545		if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
 546			MPTCP_INC_STATS(sock_net(sk),
 547					MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
 548			mptcp_do_fallback(sk);
 549			pr_fallback(msk);
 550			goto fallback;
 551		}
 552
 553		if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
 554			WRITE_ONCE(msk->csum_enabled, true);
 555		if (mp_opt.deny_join_id0)
 556			WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
 557		subflow->mp_capable = 1;
 
 558		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
 559		mptcp_finish_connect(sk);
 560		mptcp_active_enable(parent);
 561		mptcp_propagate_state(parent, sk, subflow, &mp_opt);
 562	} else if (subflow->request_join) {
 563		u8 hmac[SHA256_DIGEST_SIZE];
 564
 565		if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
 566			subflow->reset_reason = MPTCP_RST_EMPTCP;
 567			goto do_reset;
 568		}
 569
 570		subflow->backup = mp_opt.backup;
 571		subflow->thmac = mp_opt.thmac;
 572		subflow->remote_nonce = mp_opt.nonce;
 573		WRITE_ONCE(subflow->remote_id, mp_opt.join_id);
 574		pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d\n",
 575			 subflow, subflow->thmac, subflow->remote_nonce,
 576			 subflow->backup);
 577
 578		if (!subflow_thmac_valid(subflow)) {
 579			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
 580			subflow->reset_reason = MPTCP_RST_EMPTCP;
 581			goto do_reset;
 582		}
 583
 584		if (!mptcp_finish_join(sk))
 585			goto do_reset;
 586
 587		subflow_generate_hmac(subflow->local_key, subflow->remote_key,
 588				      subflow->local_nonce,
 589				      subflow->remote_nonce,
 590				      hmac);
 591		memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
 592
 593		subflow->mp_join = 1;
 594		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 595
 596		if (subflow->backup)
 597			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKBACKUPRX);
 598
 599		if (subflow_use_different_dport(msk, sk)) {
 600			pr_debug("synack inet_dport=%d %d\n",
 601				 ntohs(inet_sk(sk)->inet_dport),
 602				 ntohs(inet_sk(parent)->inet_dport));
 603			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
 604		}
 605	} else if (mptcp_check_fallback(sk)) {
 606		/* It looks like MPTCP is blocked, while TCP is not */
 607		if (subflow->mpc_drop)
 608			mptcp_active_disable(parent);
 609fallback:
 610		mptcp_propagate_state(parent, sk, subflow, NULL);
 
 611	}
 612	return;
 613
 614do_reset:
 615	subflow->reset_transient = 0;
 616	mptcp_subflow_reset(sk);
 617}
 618
 619static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
 620{
 621	WARN_ON_ONCE(local_id < 0 || local_id > 255);
 622	WRITE_ONCE(subflow->local_id, local_id);
 623}
 624
 625static int subflow_chk_local_id(struct sock *sk)
 626{
 627	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 628	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 629	int err;
 630
 631	if (likely(subflow->local_id >= 0))
 632		return 0;
 633
 634	err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
 635	if (err < 0)
 636		return err;
 637
 638	subflow_set_local_id(subflow, err);
 639	subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk);
 640
 641	return 0;
 642}
 643
 644static int subflow_rebuild_header(struct sock *sk)
 645{
 646	int err = subflow_chk_local_id(sk);
 647
 648	if (unlikely(err < 0))
 649		return err;
 650
 651	return inet_sk_rebuild_header(sk);
 652}
 653
 654#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 655static int subflow_v6_rebuild_header(struct sock *sk)
 656{
 657	int err = subflow_chk_local_id(sk);
 658
 659	if (unlikely(err < 0))
 660		return err;
 661
 662	return inet6_sk_rebuild_header(sk);
 663}
 664#endif
 665
 666static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
 667static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
 668
 669static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 670{
 671	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 672
 673	pr_debug("subflow=%p\n", subflow);
 674
 675	/* Never answer to SYNs sent to broadcast or multicast */
 676	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 677		goto drop;
 678
 679	return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
 680				&subflow_request_sock_ipv4_ops,
 681				sk, skb);
 682drop:
 683	tcp_listendrop(sk);
 684	return 0;
 685}
 686
 687static void subflow_v4_req_destructor(struct request_sock *req)
 688{
 689	subflow_req_destructor(req);
 690	tcp_request_sock_ops.destructor(req);
 691}
 692
 693#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 694static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
 695static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
 696static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
 697static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
 698static struct proto tcpv6_prot_override __ro_after_init;
 699
 700static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 701{
 702	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 703
 704	pr_debug("subflow=%p\n", subflow);
 705
 706	if (skb->protocol == htons(ETH_P_IP))
 707		return subflow_v4_conn_request(sk, skb);
 708
 709	if (!ipv6_unicast_destination(skb))
 710		goto drop;
 711
 712	if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
 713		__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
 714		return 0;
 715	}
 716
 717	return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
 718				&subflow_request_sock_ipv6_ops, sk, skb);
 719
 720drop:
 721	tcp_listendrop(sk);
 722	return 0; /* don't send reset */
 723}
 724
 725static void subflow_v6_req_destructor(struct request_sock *req)
 726{
 727	subflow_req_destructor(req);
 728	tcp6_request_sock_ops.destructor(req);
 729}
 730#endif
 731
 732struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
 733					       struct sock *sk_listener,
 734					       bool attach_listener)
 735{
 736	if (ops->family == AF_INET)
 737		ops = &mptcp_subflow_v4_request_sock_ops;
 738#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 739	else if (ops->family == AF_INET6)
 740		ops = &mptcp_subflow_v6_request_sock_ops;
 741#endif
 742
 743	return inet_reqsk_alloc(ops, sk_listener, attach_listener);
 744}
 745EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
 746
 747/* validate hmac received in third ACK */
 748static bool subflow_hmac_valid(const struct request_sock *req,
 749			       const struct mptcp_options_received *mp_opt)
 750{
 751	const struct mptcp_subflow_request_sock *subflow_req;
 752	u8 hmac[SHA256_DIGEST_SIZE];
 753	struct mptcp_sock *msk;
 754
 755	subflow_req = mptcp_subflow_rsk(req);
 756	msk = subflow_req->msk;
 757	if (!msk)
 758		return false;
 759
 760	subflow_generate_hmac(READ_ONCE(msk->remote_key),
 761			      READ_ONCE(msk->local_key),
 762			      subflow_req->remote_nonce,
 763			      subflow_req->local_nonce, hmac);
 764
 765	return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
 766}
 767
 
 
 
 
 
 
 
 768static void subflow_ulp_fallback(struct sock *sk,
 769				 struct mptcp_subflow_context *old_ctx)
 770{
 771	struct inet_connection_sock *icsk = inet_csk(sk);
 772
 773	mptcp_subflow_tcp_fallback(sk, old_ctx);
 774	icsk->icsk_ulp_ops = NULL;
 775	rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
 776	tcp_sk(sk)->is_mptcp = 0;
 777
 778	mptcp_subflow_ops_undo_override(sk);
 779}
 780
 781void mptcp_subflow_drop_ctx(struct sock *ssk)
 782{
 783	struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
 784
 785	if (!ctx)
 786		return;
 787
 788	list_del(&mptcp_subflow_ctx(ssk)->node);
 789	if (inet_csk(ssk)->icsk_ulp_ops) {
 790		subflow_ulp_fallback(ssk, ctx);
 791		if (ctx->conn)
 792			sock_put(ctx->conn);
 793	}
 794
 795	kfree_rcu(ctx, rcu);
 796}
 797
 798void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
 799				       struct mptcp_subflow_context *subflow,
 800				       const struct mptcp_options_received *mp_opt)
 801{
 
 
 802	subflow_set_remote_key(msk, subflow, mp_opt);
 803	WRITE_ONCE(subflow->fully_established, true);
 804	WRITE_ONCE(msk->fully_established, true);
 805
 806	if (subflow->is_mptfo)
 807		__mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
 808}
 809
 810static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 811					  struct sk_buff *skb,
 812					  struct request_sock *req,
 813					  struct dst_entry *dst,
 814					  struct request_sock *req_unhash,
 815					  bool *own_req)
 816{
 817	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
 818	struct mptcp_subflow_request_sock *subflow_req;
 819	struct mptcp_options_received mp_opt;
 820	bool fallback, fallback_is_fatal;
 821	enum sk_rst_reason reason;
 822	struct mptcp_sock *owner;
 823	struct sock *child;
 824
 825	pr_debug("listener=%p, req=%p, conn=%p\n", listener, req, listener->conn);
 826
 827	/* After child creation we must look for MPC even when options
 828	 * are not parsed
 829	 */
 830	mp_opt.suboptions = 0;
 831
 832	/* hopefully temporary handling for MP_JOIN+syncookie */
 833	subflow_req = mptcp_subflow_rsk(req);
 834	fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
 835	fallback = !tcp_rsk(req)->is_mptcp;
 836	if (fallback)
 837		goto create_child;
 838
 839	/* if the sk is MP_CAPABLE, we try to fetch the client key */
 840	if (subflow_req->mp_capable) {
 841		/* we can receive and accept an in-window, out-of-order pkt,
 842		 * which may not carry the MP_CAPABLE opt even on mptcp enabled
 843		 * paths: always try to extract the peer key, and fallback
 844		 * for packets missing it.
 845		 * Even OoO DSS packets coming legitly after dropped or
 846		 * reordered MPC will cause fallback, but we don't have other
 847		 * options.
 848		 */
 849		mptcp_get_options(skb, &mp_opt);
 850		if (!(mp_opt.suboptions &
 851		      (OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK)))
 852			fallback = true;
 
 
 853
 
 
 
 854	} else if (subflow_req->mp_join) {
 855		mptcp_get_options(skb, &mp_opt);
 856		if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
 857		    !subflow_hmac_valid(req, &mp_opt) ||
 858		    !mptcp_can_accept_new_subflow(subflow_req->msk)) {
 859			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
 860			fallback = true;
 861		}
 862	}
 863
 864create_child:
 865	child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
 866						     req_unhash, own_req);
 867
 868	if (child && *own_req) {
 869		struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
 870
 871		tcp_rsk(req)->drop_req = false;
 872
 873		/* we need to fallback on ctx allocation failure and on pre-reqs
 874		 * checking above. In the latter scenario we additionally need
 875		 * to reset the context to non MPTCP status.
 876		 */
 877		if (!ctx || fallback) {
 878			if (fallback_is_fatal) {
 879				subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
 880				goto dispose_child;
 881			}
 882			goto fallback;
 
 
 
 
 883		}
 884
 885		/* ssk inherits options of listener sk */
 886		ctx->setsockopt_seq = listener->setsockopt_seq;
 887
 888		if (ctx->mp_capable) {
 889			ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
 890			if (!ctx->conn)
 891				goto fallback;
 892
 893			ctx->subflow_id = 1;
 894			owner = mptcp_sk(ctx->conn);
 895			mptcp_pm_new_connection(owner, child, 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 896
 897			/* with OoO packets we can reach here without ingress
 898			 * mpc option
 899			 */
 900			if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
 901				mptcp_pm_fully_established(owner, child);
 902				ctx->pm_notified = 1;
 903			}
 904		} else if (ctx->mp_join) {
 
 
 905			owner = subflow_req->msk;
 906			if (!owner) {
 907				subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 908				goto dispose_child;
 909			}
 910
 911			/* move the msk reference ownership to the subflow */
 912			subflow_req->msk = NULL;
 913			ctx->conn = (struct sock *)owner;
 914
 915			if (subflow_use_different_sport(owner, sk)) {
 916				pr_debug("ack inet_sport=%d %d\n",
 917					 ntohs(inet_sk(sk)->inet_sport),
 918					 ntohs(inet_sk((struct sock *)owner)->inet_sport));
 919				if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
 920					SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
 921					subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
 922					goto dispose_child;
 923				}
 924				SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
 925			}
 926
 927			if (!mptcp_finish_join(child)) {
 928				struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(child);
 929
 930				subflow_add_reset_reason(skb, subflow->reset_reason);
 931				goto dispose_child;
 932			}
 933
 934			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
 935			tcp_rsk(req)->drop_req = true;
 936		}
 937	}
 938
 
 
 
 
 
 939	/* check for expected invariant - should never trigger, just help
 940	 * catching earlier subtle bugs
 941	 */
 942	WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
 943		     (!mptcp_subflow_ctx(child) ||
 944		      !mptcp_subflow_ctx(child)->conn));
 945	return child;
 946
 947dispose_child:
 948	mptcp_subflow_drop_ctx(child);
 949	tcp_rsk(req)->drop_req = true;
 950	inet_csk_prepare_for_destroy_sock(child);
 951	tcp_done(child);
 952	reason = mptcp_get_rst_reason(skb);
 953	req->rsk_ops->send_reset(sk, skb, reason);
 954
 955	/* The last child reference will be released by the caller */
 956	return child;
 957
 958fallback:
 959	if (fallback)
 960		SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
 961	mptcp_subflow_drop_ctx(child);
 962	return child;
 963}
 964
 965static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
 966static struct proto tcp_prot_override __ro_after_init;
 967
 968enum mapping_status {
 969	MAPPING_OK,
 970	MAPPING_INVALID,
 971	MAPPING_EMPTY,
 972	MAPPING_DATA_FIN,
 973	MAPPING_DUMMY,
 974	MAPPING_BAD_CSUM,
 975	MAPPING_NODSS
 976};
 977
 978static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
 979{
 980	pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d\n",
 981		 ssn, subflow->map_subflow_seq, subflow->map_data_len);
 982}
 983
 984static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
 985{
 986	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 987	unsigned int skb_consumed;
 988
 989	skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
 990	if (unlikely(skb_consumed >= skb->len)) {
 991		DEBUG_NET_WARN_ON_ONCE(1);
 992		return true;
 993	}
 994
 995	return skb->len - skb_consumed <= subflow->map_data_len -
 996					  mptcp_subflow_get_map_offset(subflow);
 997}
 998
 999static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
1000{
1001	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1002	u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1003
1004	if (unlikely(before(ssn, subflow->map_subflow_seq))) {
1005		/* Mapping covers data later in the subflow stream,
1006		 * currently unsupported.
1007		 */
1008		dbg_bad_map(subflow, ssn);
1009		return false;
1010	}
1011	if (unlikely(!before(ssn, subflow->map_subflow_seq +
1012				  subflow->map_data_len))) {
1013		/* Mapping does covers past subflow data, invalid */
1014		dbg_bad_map(subflow, ssn);
1015		return false;
1016	}
1017	return true;
1018}
1019
1020static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
1021					      bool csum_reqd)
1022{
1023	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1024	u32 offset, seq, delta;
1025	__sum16 csum;
1026	int len;
1027
1028	if (!csum_reqd)
1029		return MAPPING_OK;
1030
1031	/* mapping already validated on previous traversal */
1032	if (subflow->map_csum_len == subflow->map_data_len)
1033		return MAPPING_OK;
1034
1035	/* traverse the receive queue, ensuring it contains a full
1036	 * DSS mapping and accumulating the related csum.
1037	 * Preserve the accoumlate csum across multiple calls, to compute
1038	 * the csum only once
1039	 */
1040	delta = subflow->map_data_len - subflow->map_csum_len;
1041	for (;;) {
1042		seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
1043		offset = seq - TCP_SKB_CB(skb)->seq;
1044
1045		/* if the current skb has not been accounted yet, csum its contents
1046		 * up to the amount covered by the current DSS
1047		 */
1048		if (offset < skb->len) {
1049			__wsum csum;
1050
1051			len = min(skb->len - offset, delta);
1052			csum = skb_checksum(skb, offset, len, 0);
1053			subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
1054								subflow->map_csum_len);
1055
1056			delta -= len;
1057			subflow->map_csum_len += len;
1058		}
1059		if (delta == 0)
1060			break;
1061
1062		if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
1063			/* if this subflow is closed, the partial mapping
1064			 * will be never completed; flush the pending skbs, so
1065			 * that subflow_sched_work_if_closed() can kick in
1066			 */
1067			if (unlikely(ssk->sk_state == TCP_CLOSE))
1068				while ((skb = skb_peek(&ssk->sk_receive_queue)))
1069					sk_eat_skb(ssk, skb);
1070
1071			/* not enough data to validate the csum */
1072			return MAPPING_EMPTY;
1073		}
1074
1075		/* the DSS mapping for next skbs will be validated later,
1076		 * when a get_mapping_status call will process such skb
1077		 */
1078		skb = skb->next;
1079	}
1080
1081	/* note that 'map_data_len' accounts only for the carried data, does
1082	 * not include the eventual seq increment due to the data fin,
1083	 * while the pseudo header requires the original DSS data len,
1084	 * including that
1085	 */
1086	csum = __mptcp_make_csum(subflow->map_seq,
1087				 subflow->map_subflow_seq,
1088				 subflow->map_data_len + subflow->map_data_fin,
1089				 subflow->map_data_csum);
1090	if (unlikely(csum)) {
1091		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
1092		return MAPPING_BAD_CSUM;
1093	}
1094
1095	subflow->valid_csum_seen = 1;
1096	return MAPPING_OK;
1097}
1098
1099static enum mapping_status get_mapping_status(struct sock *ssk,
1100					      struct mptcp_sock *msk)
1101{
1102	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1103	bool csum_reqd = READ_ONCE(msk->csum_enabled);
1104	struct mptcp_ext *mpext;
1105	struct sk_buff *skb;
1106	u16 data_len;
1107	u64 map_seq;
1108
1109	skb = skb_peek(&ssk->sk_receive_queue);
1110	if (!skb)
1111		return MAPPING_EMPTY;
1112
1113	if (mptcp_check_fallback(ssk))
1114		return MAPPING_DUMMY;
1115
1116	mpext = mptcp_get_ext(skb);
1117	if (!mpext || !mpext->use_map) {
1118		if (!subflow->map_valid && !skb->len) {
1119			/* the TCP stack deliver 0 len FIN pkt to the receive
1120			 * queue, that is the only 0len pkts ever expected here,
1121			 * and we can admit no mapping only for 0 len pkts
1122			 */
1123			if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
1124				WARN_ONCE(1, "0len seq %d:%d flags %x",
1125					  TCP_SKB_CB(skb)->seq,
1126					  TCP_SKB_CB(skb)->end_seq,
1127					  TCP_SKB_CB(skb)->tcp_flags);
1128			sk_eat_skb(ssk, skb);
1129			return MAPPING_EMPTY;
1130		}
1131
1132		/* If the required DSS has likely been dropped by a middlebox */
1133		if (!subflow->map_valid)
1134			return MAPPING_NODSS;
1135
1136		goto validate_seq;
1137	}
1138
1139	trace_get_mapping_status(mpext);
1140
1141	data_len = mpext->data_len;
1142	if (data_len == 0) {
1143		pr_debug("infinite mapping received\n");
1144		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 
1145		return MAPPING_INVALID;
1146	}
1147
1148	if (mpext->data_fin == 1) {
1149		u64 data_fin_seq;
1150
1151		if (data_len == 1) {
1152			bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
1153								 mpext->dsn64);
1154			pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq);
1155			if (subflow->map_valid) {
1156				/* A DATA_FIN might arrive in a DSS
1157				 * option before the previous mapping
1158				 * has been fully consumed. Continue
1159				 * handling the existing mapping.
1160				 */
1161				skb_ext_del(skb, SKB_EXT_MPTCP);
1162				return MAPPING_OK;
 
 
 
 
 
1163			}
 
 
1164
1165			if (updated)
1166				mptcp_schedule_work((struct sock *)msk);
 
 
 
1167
1168			return MAPPING_DATA_FIN;
 
 
1169		}
1170
1171		data_fin_seq = mpext->data_seq + data_len - 1;
1172
1173		/* If mpext->data_seq is a 32-bit value, data_fin_seq must also
1174		 * be limited to 32 bits.
1175		 */
1176		if (!mpext->dsn64)
1177			data_fin_seq &= GENMASK_ULL(31, 0);
1178
1179		mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
1180		pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n",
1181			 data_fin_seq, mpext->dsn64);
1182
1183		/* Adjust for DATA_FIN using 1 byte of sequence space */
1184		data_len--;
1185	}
1186
1187	map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
1188	WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
1189
1190	if (subflow->map_valid) {
1191		/* Allow replacing only with an identical map */
1192		if (subflow->map_seq == map_seq &&
1193		    subflow->map_subflow_seq == mpext->subflow_seq &&
1194		    subflow->map_data_len == data_len &&
1195		    subflow->map_csum_reqd == mpext->csum_reqd) {
1196			skb_ext_del(skb, SKB_EXT_MPTCP);
1197			goto validate_csum;
1198		}
1199
1200		/* If this skb data are fully covered by the current mapping,
1201		 * the new map would need caching, which is not supported
1202		 */
1203		if (skb_is_fully_mapped(ssk, skb)) {
1204			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
1205			return MAPPING_INVALID;
1206		}
1207
1208		/* will validate the next map after consuming the current one */
1209		goto validate_csum;
1210	}
1211
1212	subflow->map_seq = map_seq;
1213	subflow->map_subflow_seq = mpext->subflow_seq;
1214	subflow->map_data_len = data_len;
1215	subflow->map_valid = 1;
1216	subflow->map_data_fin = mpext->data_fin;
1217	subflow->mpc_map = mpext->mpc_map;
1218	subflow->map_csum_reqd = mpext->csum_reqd;
1219	subflow->map_csum_len = 0;
1220	subflow->map_data_csum = csum_unfold(mpext->csum);
1221
1222	/* Cfr RFC 8684 Section 3.3.0 */
1223	if (unlikely(subflow->map_csum_reqd != csum_reqd))
1224		return MAPPING_INVALID;
1225
1226	pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
1227		 subflow->map_seq, subflow->map_subflow_seq,
1228		 subflow->map_data_len, subflow->map_csum_reqd,
1229		 subflow->map_data_csum);
1230
1231validate_seq:
1232	/* we revalidate valid mapping on new skb, because we must ensure
1233	 * the current skb is completely covered by the available mapping
1234	 */
1235	if (!validate_mapping(ssk, skb)) {
1236		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
1237		return MAPPING_INVALID;
1238	}
1239
1240	skb_ext_del(skb, SKB_EXT_MPTCP);
1241
1242validate_csum:
1243	return validate_data_csum(ssk, skb, csum_reqd);
1244}
1245
1246static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
1247				       u64 limit)
1248{
1249	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1250	bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
1251	struct tcp_sock *tp = tcp_sk(ssk);
1252	u32 offset, incr, avail_len;
1253
1254	offset = tp->copied_seq - TCP_SKB_CB(skb)->seq;
1255	if (WARN_ON_ONCE(offset > skb->len))
1256		goto out;
1257
1258	avail_len = skb->len - offset;
1259	incr = limit >= avail_len ? avail_len + fin : limit;
1260
1261	pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len,
1262		 offset, subflow->map_subflow_seq);
1263	MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
1264	tcp_sk(ssk)->copied_seq += incr;
1265
1266out:
1267	if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
1268		sk_eat_skb(ssk, skb);
1269	if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
1270		subflow->map_valid = 0;
1271}
1272
1273/* sched mptcp worker to remove the subflow if no more data is pending */
1274static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
1275{
1276	struct sock *sk = (struct sock *)msk;
1277
1278	if (likely(ssk->sk_state != TCP_CLOSE &&
1279		   (ssk->sk_state != TCP_CLOSE_WAIT ||
1280		    inet_sk_state_load(sk) != TCP_ESTABLISHED)))
1281		return;
1282
1283	if (skb_queue_empty(&ssk->sk_receive_queue) &&
1284	    !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
1285		mptcp_schedule_work(sk);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1286}
1287
1288static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
1289{
1290	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1291	unsigned long fail_tout;
1292
1293	/* graceful failure can happen only on the MPC subflow */
1294	if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
1295		return;
1296
1297	/* since the close timeout take precedence on the fail one,
1298	 * no need to start the latter when the first is already set
1299	 */
1300	if (sock_flag((struct sock *)msk, SOCK_DEAD))
1301		return;
1302
1303	/* we don't need extreme accuracy here, use a zero fail_tout as special
1304	 * value meaning no fail timeout at all;
1305	 */
1306	fail_tout = jiffies + TCP_RTO_MAX;
1307	if (!fail_tout)
1308		fail_tout = 1;
1309	WRITE_ONCE(subflow->fail_tout, fail_tout);
1310	tcp_send_ack(ssk);
1311
1312	mptcp_reset_tout_timer(msk, subflow->fail_tout);
1313}
1314
1315static bool subflow_check_data_avail(struct sock *ssk)
1316{
1317	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1318	enum mapping_status status;
1319	struct mptcp_sock *msk;
1320	struct sk_buff *skb;
1321
1322	if (!skb_peek(&ssk->sk_receive_queue))
1323		WRITE_ONCE(subflow->data_avail, false);
1324	if (subflow->data_avail)
1325		return true;
1326
1327	msk = mptcp_sk(subflow->conn);
1328	for (;;) {
1329		u64 ack_seq;
1330		u64 old_ack;
1331
1332		status = get_mapping_status(ssk, msk);
1333		trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
1334		if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
1335			     status == MAPPING_BAD_CSUM || status == MAPPING_NODSS))
1336			goto fallback;
1337
1338		if (status != MAPPING_OK)
1339			goto no_data;
1340
1341		skb = skb_peek(&ssk->sk_receive_queue);
1342		if (WARN_ON_ONCE(!skb))
1343			goto no_data;
1344
1345		if (unlikely(!READ_ONCE(msk->can_ack)))
1346			goto fallback;
1347
1348		old_ack = READ_ONCE(msk->ack_seq);
1349		ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
1350		pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack,
1351			 ack_seq);
1352		if (unlikely(before64(ack_seq, old_ack))) {
1353			mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
1354			continue;
1355		}
1356
1357		WRITE_ONCE(subflow->data_avail, true);
1358		break;
1359	}
1360	return true;
1361
1362no_data:
1363	subflow_sched_work_if_closed(msk, ssk);
1364	return false;
1365
1366fallback:
1367	if (!__mptcp_check_fallback(msk)) {
1368		/* RFC 8684 section 3.7. */
1369		if (status == MAPPING_BAD_CSUM &&
1370		    (subflow->mp_join || subflow->valid_csum_seen)) {
1371			subflow->send_mp_fail = 1;
1372
1373			if (!READ_ONCE(msk->allow_infinite_fallback)) {
1374				subflow->reset_transient = 0;
1375				subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
1376				goto reset;
1377			}
1378			mptcp_subflow_fail(msk, ssk);
1379			WRITE_ONCE(subflow->data_avail, true);
1380			return true;
1381		}
1382
1383		if (!READ_ONCE(msk->allow_infinite_fallback)) {
1384			/* fatal protocol error, close the socket.
1385			 * subflow_error_report() will introduce the appropriate barriers
1386			 */
1387			subflow->reset_transient = 0;
1388			subflow->reset_reason = status == MAPPING_NODSS ?
1389						MPTCP_RST_EMIDDLEBOX :
1390						MPTCP_RST_EMPTCP;
1391
1392reset:
1393			WRITE_ONCE(ssk->sk_err, EBADMSG);
1394			tcp_set_state(ssk, TCP_CLOSE);
1395			while ((skb = skb_peek(&ssk->sk_receive_queue)))
1396				sk_eat_skb(ssk, skb);
1397			mptcp_send_active_reset_reason(ssk);
1398			WRITE_ONCE(subflow->data_avail, false);
1399			return false;
1400		}
1401
1402		mptcp_do_fallback(ssk);
1403	}
1404
1405	skb = skb_peek(&ssk->sk_receive_queue);
1406	subflow->map_valid = 1;
1407	subflow->map_seq = READ_ONCE(msk->ack_seq);
1408	subflow->map_data_len = skb->len;
1409	subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
1410	WRITE_ONCE(subflow->data_avail, true);
1411	return true;
1412}
1413
1414bool mptcp_subflow_data_available(struct sock *sk)
1415{
1416	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1417
1418	/* check if current mapping is still valid */
1419	if (subflow->map_valid &&
1420	    mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
1421		subflow->map_valid = 0;
1422		WRITE_ONCE(subflow->data_avail, false);
1423
1424		pr_debug("Done with mapping: seq=%u data_len=%u\n",
1425			 subflow->map_subflow_seq,
1426			 subflow->map_data_len);
1427	}
1428
1429	return subflow_check_data_avail(sk);
1430}
1431
1432/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
1433 * not the ssk one.
1434 *
1435 * In mptcp, rwin is about the mptcp-level connection data.
1436 *
1437 * Data that is still on the ssk rx queue can thus be ignored,
1438 * as far as mptcp peer is concerned that data is still inflight.
1439 * DSS ACK is updated when skb is moved to the mptcp rx queue.
1440 */
1441void mptcp_space(const struct sock *ssk, int *space, int *full_space)
1442{
1443	const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
1444	const struct sock *sk = subflow->conn;
1445
1446	*space = __mptcp_space(sk);
1447	*full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1448}
1449
1450static void subflow_error_report(struct sock *ssk)
1451{
1452	struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1453
1454	/* bail early if this is a no-op, so that we avoid introducing a
1455	 * problematic lockdep dependency between TCP accept queue lock
1456	 * and msk socket spinlock
1457	 */
1458	if (!sk->sk_socket)
1459		return;
1460
1461	mptcp_data_lock(sk);
1462	if (!sock_owned_by_user(sk))
1463		__mptcp_error_report(sk);
1464	else
1465		__set_bit(MPTCP_ERROR_REPORT,  &mptcp_sk(sk)->cb_flags);
1466	mptcp_data_unlock(sk);
1467}
1468
1469static void subflow_data_ready(struct sock *sk)
1470{
1471	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1472	u16 state = 1 << inet_sk_state_load(sk);
1473	struct sock *parent = subflow->conn;
1474	struct mptcp_sock *msk;
1475
1476	trace_sk_data_ready(sk);
1477
1478	msk = mptcp_sk(parent);
1479	if (state & TCPF_LISTEN) {
1480		/* MPJ subflow are removed from accept queue before reaching here,
1481		 * avoid stray wakeups
1482		 */
1483		if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
1484			return;
1485
1486		parent->sk_data_ready(parent);
1487		return;
1488	}
1489
1490	WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
1491		     !subflow->mp_join && !(state & TCPF_CLOSE));
1492
1493	if (mptcp_subflow_data_available(sk)) {
1494		mptcp_data_ready(parent, sk);
1495
1496		/* subflow-level lowat test are not relevant.
1497		 * respect the msk-level threshold eventually mandating an immediate ack
1498		 */
1499		if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
1500		    (tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
1501			inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
1502	} else if (unlikely(sk->sk_err)) {
1503		subflow_error_report(sk);
1504	}
1505}
1506
1507static void subflow_write_space(struct sock *ssk)
1508{
1509	struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
1510
1511	mptcp_propagate_sndbuf(sk, ssk);
1512	mptcp_write_space(sk);
1513}
1514
1515static const struct inet_connection_sock_af_ops *
1516subflow_default_af_ops(struct sock *sk)
1517{
1518#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1519	if (sk->sk_family == AF_INET6)
1520		return &subflow_v6_specific;
1521#endif
1522	return &subflow_specific;
1523}
1524
1525#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1526void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
1527{
1528	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1529	struct inet_connection_sock *icsk = inet_csk(sk);
1530	const struct inet_connection_sock_af_ops *target;
1531
1532	target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
1533
1534	pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d\n",
1535		 subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
1536
1537	if (likely(icsk->icsk_af_ops == target))
1538		return;
1539
1540	subflow->icsk_af_ops = icsk->icsk_af_ops;
1541	icsk->icsk_af_ops = target;
1542}
1543#endif
1544
1545void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
1546			 struct sockaddr_storage *addr,
1547			 unsigned short family)
1548{
1549	memset(addr, 0, sizeof(*addr));
1550	addr->ss_family = family;
1551	if (addr->ss_family == AF_INET) {
1552		struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
1553
1554		if (info->family == AF_INET)
1555			in_addr->sin_addr = info->addr;
1556#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1557		else if (ipv6_addr_v4mapped(&info->addr6))
1558			in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
1559#endif
1560		in_addr->sin_port = info->port;
1561	}
1562#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1563	else if (addr->ss_family == AF_INET6) {
1564		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
1565
1566		if (info->family == AF_INET)
1567			ipv6_addr_set_v4mapped(info->addr.s_addr,
1568					       &in6_addr->sin6_addr);
1569		else
1570			in6_addr->sin6_addr = info->addr6;
1571		in6_addr->sin6_port = info->port;
1572	}
1573#endif
1574}
1575
1576int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local,
1577			    const struct mptcp_addr_info *remote)
1578{
1579	struct mptcp_sock *msk = mptcp_sk(sk);
1580	struct mptcp_subflow_context *subflow;
1581	int local_id = local->addr.id;
1582	struct sockaddr_storage addr;
1583	int remote_id = remote->id;
 
1584	int err = -ENOTCONN;
1585	struct socket *sf;
1586	struct sock *ssk;
1587	u32 remote_token;
1588	int addrlen;
 
 
1589
1590	/* The userspace PM sent the request too early? */
1591	if (!mptcp_is_fully_established(sk))
1592		goto err_out;
1593
1594	err = mptcp_subflow_create_socket(sk, local->addr.family, &sf);
1595	if (err) {
1596		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCREATSKERR);
1597		pr_debug("msk=%p local=%d remote=%d create sock error: %d\n",
1598			 msk, local_id, remote_id, err);
1599		goto err_out;
1600	}
1601
1602	ssk = sf->sk;
1603	subflow = mptcp_subflow_ctx(ssk);
1604	do {
1605		get_random_bytes(&subflow->local_nonce, sizeof(u32));
1606	} while (!subflow->local_nonce);
1607
1608	/* if 'IPADDRANY', the ID will be set later, after the routing */
1609	if (local->addr.family == AF_INET) {
1610		if (!local->addr.addr.s_addr)
1611			local_id = -1;
1612#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1613	} else if (sk->sk_family == AF_INET6) {
1614		if (ipv6_addr_any(&local->addr.addr6))
1615			local_id = -1;
1616#endif
1617	}
1618
1619	if (local_id >= 0)
1620		subflow_set_local_id(subflow, local_id);
1621
 
 
1622	subflow->remote_key_valid = 1;
1623	subflow->remote_key = READ_ONCE(msk->remote_key);
1624	subflow->local_key = READ_ONCE(msk->local_key);
1625	subflow->token = msk->token;
1626	mptcp_info2sockaddr(&local->addr, &addr, ssk->sk_family);
1627
1628	addrlen = sizeof(struct sockaddr_in);
1629#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1630	if (addr.ss_family == AF_INET6)
1631		addrlen = sizeof(struct sockaddr_in6);
1632#endif
1633	ssk->sk_bound_dev_if = local->ifindex;
 
 
1634	err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
1635	if (err) {
1636		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR);
1637		pr_debug("msk=%p local=%d remote=%d bind error: %d\n",
1638			 msk, local_id, remote_id, err);
1639		goto failed;
1640	}
1641
1642	mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
1643	pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d\n", msk,
1644		 remote_token, local_id, remote_id);
1645	subflow->remote_token = remote_token;
1646	WRITE_ONCE(subflow->remote_id, remote_id);
1647	subflow->request_join = 1;
1648	subflow->request_bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
1649	subflow->subflow_id = msk->subflow_id++;
1650	mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
1651
1652	sock_hold(ssk);
1653	list_add_tail(&subflow->node, &msk->conn_list);
1654	err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
1655	if (err && err != -EINPROGRESS) {
1656		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCONNECTERR);
1657		pr_debug("msk=%p local=%d remote=%d connect error: %d\n",
1658			 msk, local_id, remote_id, err);
1659		goto failed_unlink;
1660	}
1661
1662	MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTX);
1663
1664	/* discard the subflow socket */
1665	mptcp_sock_graft(ssk, sk->sk_socket);
1666	iput(SOCK_INODE(sf));
1667	WRITE_ONCE(msk->allow_infinite_fallback, false);
1668	mptcp_stop_tout_timer(sk);
1669	return 0;
1670
1671failed_unlink:
1672	list_del(&subflow->node);
1673	sock_put(mptcp_subflow_tcp_sock(subflow));
1674
1675failed:
1676	subflow->disposable = 1;
1677	sock_release(sf);
1678
1679err_out:
1680	/* we account subflows before the creation, and this failures will not
1681	 * be caught by sk_state_change()
1682	 */
1683	mptcp_pm_close_subflow(msk);
1684	return err;
1685}
1686
1687static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
1688{
1689#ifdef CONFIG_SOCK_CGROUP_DATA
1690	struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
1691				*child_skcd = &child->sk_cgrp_data;
1692
1693	/* only the additional subflows created by kworkers have to be modified */
1694	if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
1695	    cgroup_id(sock_cgroup_ptr(child_skcd))) {
1696#ifdef CONFIG_MEMCG
1697		struct mem_cgroup *memcg = parent->sk_memcg;
1698
1699		mem_cgroup_sk_free(child);
1700		if (memcg && css_tryget(&memcg->css))
1701			child->sk_memcg = memcg;
1702#endif /* CONFIG_MEMCG */
1703
1704		cgroup_sk_free(child_skcd);
1705		*child_skcd = *parent_skcd;
1706		cgroup_sk_clone(child_skcd);
1707	}
1708#endif /* CONFIG_SOCK_CGROUP_DATA */
1709}
1710
1711static void mptcp_subflow_ops_override(struct sock *ssk)
1712{
1713#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1714	if (ssk->sk_prot == &tcpv6_prot)
1715		ssk->sk_prot = &tcpv6_prot_override;
1716	else
1717#endif
1718		ssk->sk_prot = &tcp_prot_override;
1719}
1720
1721static void mptcp_subflow_ops_undo_override(struct sock *ssk)
1722{
1723#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1724	if (ssk->sk_prot == &tcpv6_prot_override)
1725		ssk->sk_prot = &tcpv6_prot;
1726	else
1727#endif
1728		ssk->sk_prot = &tcp_prot;
1729}
1730
1731int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
1732				struct socket **new_sock)
1733{
1734	struct mptcp_subflow_context *subflow;
1735	struct net *net = sock_net(sk);
1736	struct socket *sf;
1737	int err;
1738
1739	/* un-accepted server sockets can reach here - on bad configuration
1740	 * bail early to avoid greater trouble later
1741	 */
1742	if (unlikely(!sk->sk_socket))
1743		return -EINVAL;
1744
1745	err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
1746	if (err)
1747		return err;
1748
1749	lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
1750
1751	err = security_mptcp_add_subflow(sk, sf->sk);
1752	if (err)
1753		goto err_free;
1754
1755	/* the newly created socket has to be in the same cgroup as its parent */
1756	mptcp_attach_cgroup(sk, sf->sk);
1757
1758	/* kernel sockets do not by default acquire net ref, but TCP timer
1759	 * needs it.
1760	 * Update ns_tracker to current stack trace and refcounted tracker.
1761	 */
1762	sk_net_refcnt_upgrade(sf->sk);
 
 
 
1763	err = tcp_set_ulp(sf->sk, "mptcp");
1764	if (err)
1765		goto err_free;
1766
1767	mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk);
1768	release_sock(sf->sk);
1769
1770	/* the newly created socket really belongs to the owning MPTCP
 
 
 
 
 
1771	 * socket, even if for additional subflows the allocation is performed
1772	 * by a kernel workqueue. Adjust inode references, so that the
1773	 * procfs/diag interfaces really show this one belonging to the correct
1774	 * user.
1775	 */
1776	SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
1777	SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
1778	SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
1779
1780	subflow = mptcp_subflow_ctx(sf->sk);
1781	pr_debug("subflow=%p\n", subflow);
1782
1783	*new_sock = sf;
1784	sock_hold(sk);
1785	subflow->conn = sk;
1786	mptcp_subflow_ops_override(sf->sk);
1787
1788	return 0;
1789
1790err_free:
1791	release_sock(sf->sk);
1792	sock_release(sf);
1793	return err;
1794}
1795
1796static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
1797							gfp_t priority)
1798{
1799	struct inet_connection_sock *icsk = inet_csk(sk);
1800	struct mptcp_subflow_context *ctx;
1801
1802	ctx = kzalloc(sizeof(*ctx), priority);
1803	if (!ctx)
1804		return NULL;
1805
1806	rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
1807	INIT_LIST_HEAD(&ctx->node);
1808	INIT_LIST_HEAD(&ctx->delegated_node);
1809
1810	pr_debug("subflow=%p\n", ctx);
1811
1812	ctx->tcp_sock = sk;
1813	WRITE_ONCE(ctx->local_id, -1);
1814
1815	return ctx;
1816}
1817
1818static void __subflow_state_change(struct sock *sk)
1819{
1820	struct socket_wq *wq;
1821
1822	rcu_read_lock();
1823	wq = rcu_dereference(sk->sk_wq);
1824	if (skwq_has_sleeper(wq))
1825		wake_up_interruptible_all(&wq->wait);
1826	rcu_read_unlock();
1827}
1828
1829static bool subflow_is_done(const struct sock *sk)
1830{
1831	return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
1832}
1833
1834static void subflow_state_change(struct sock *sk)
1835{
1836	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1837	struct sock *parent = subflow->conn;
1838	struct mptcp_sock *msk;
1839
1840	__subflow_state_change(sk);
1841
1842	msk = mptcp_sk(parent);
1843	if (subflow_simultaneous_connect(sk)) {
 
1844		mptcp_do_fallback(sk);
1845		pr_fallback(msk);
 
1846		subflow->conn_finished = 1;
1847		mptcp_propagate_state(parent, sk, subflow, NULL);
1848	}
1849
1850	/* as recvmsg() does not acquire the subflow socket for ssk selection
1851	 * a fin packet carrying a DSS can be unnoticed if we don't trigger
1852	 * the data available machinery here.
1853	 */
1854	if (mptcp_subflow_data_available(sk))
1855		mptcp_data_ready(parent, sk);
1856	else if (unlikely(sk->sk_err))
1857		subflow_error_report(sk);
1858
1859	subflow_sched_work_if_closed(mptcp_sk(parent), sk);
1860
1861	/* when the fallback subflow closes the rx side, trigger a 'dummy'
1862	 * ingress data fin, so that the msk state will follow along
1863	 */
1864	if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
1865	    mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
1866		mptcp_schedule_work(parent);
1867}
1868
1869void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
1870{
1871	struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
1872	struct request_sock *req, *head, *tail;
1873	struct mptcp_subflow_context *subflow;
1874	struct sock *sk, *ssk;
1875
1876	/* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
1877	 * Splice the req list, so that accept() can not reach the pending ssk after
1878	 * the listener socket is released below.
1879	 */
1880	spin_lock_bh(&queue->rskq_lock);
1881	head = queue->rskq_accept_head;
1882	tail = queue->rskq_accept_tail;
1883	queue->rskq_accept_head = NULL;
1884	queue->rskq_accept_tail = NULL;
1885	spin_unlock_bh(&queue->rskq_lock);
1886
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1887	if (!head)
1888		return;
1889
1890	/* can't acquire the msk socket lock under the subflow one,
1891	 * or will cause ABBA deadlock
1892	 */
1893	release_sock(listener_ssk);
1894
1895	for (req = head; req; req = req->dl_next) {
1896		ssk = req->sk;
1897		if (!sk_is_mptcp(ssk))
1898			continue;
1899
1900		subflow = mptcp_subflow_ctx(ssk);
1901		if (!subflow || !subflow->conn)
1902			continue;
1903
1904		sk = subflow->conn;
1905		sock_hold(sk);
1906
1907		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
1908		__mptcp_unaccepted_force_close(sk);
1909		release_sock(sk);
1910
1911		/* lockdep will report a false positive ABBA deadlock
1912		 * between cancel_work_sync and the listener socket.
1913		 * The involved locks belong to different sockets WRT
1914		 * the existing AB chain.
1915		 * Using a per socket key is problematic as key
1916		 * deregistration requires process context and must be
1917		 * performed at socket disposal time, in atomic
1918		 * context.
1919		 * Just tell lockdep to consider the listener socket
1920		 * released here.
1921		 */
1922		mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
1923		mptcp_cancel_work(sk);
1924		mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
1925
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1926		sock_put(sk);
1927	}
1928
1929	/* we are still under the listener msk socket lock */
1930	lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
1931
1932	/* restore the listener queue, to let the TCP code clean it up */
1933	spin_lock_bh(&queue->rskq_lock);
1934	WARN_ON_ONCE(queue->rskq_accept_head);
1935	queue->rskq_accept_head = head;
1936	queue->rskq_accept_tail = tail;
1937	spin_unlock_bh(&queue->rskq_lock);
1938}
1939
1940static int subflow_ulp_init(struct sock *sk)
1941{
1942	struct inet_connection_sock *icsk = inet_csk(sk);
1943	struct mptcp_subflow_context *ctx;
1944	struct tcp_sock *tp = tcp_sk(sk);
1945	int err = 0;
1946
1947	/* disallow attaching ULP to a socket unless it has been
1948	 * created with sock_create_kern()
1949	 */
1950	if (!sk->sk_kern_sock) {
1951		err = -EOPNOTSUPP;
1952		goto out;
1953	}
1954
1955	ctx = subflow_create_ctx(sk, GFP_KERNEL);
1956	if (!ctx) {
1957		err = -ENOMEM;
1958		goto out;
1959	}
1960
1961	pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family);
1962
1963	tp->is_mptcp = 1;
1964	ctx->icsk_af_ops = icsk->icsk_af_ops;
1965	icsk->icsk_af_ops = subflow_default_af_ops(sk);
1966	ctx->tcp_state_change = sk->sk_state_change;
1967	ctx->tcp_error_report = sk->sk_error_report;
1968
1969	WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
1970	WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
1971
1972	sk->sk_data_ready = subflow_data_ready;
1973	sk->sk_write_space = subflow_write_space;
1974	sk->sk_state_change = subflow_state_change;
1975	sk->sk_error_report = subflow_error_report;
1976out:
1977	return err;
1978}
1979
1980static void subflow_ulp_release(struct sock *ssk)
1981{
1982	struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
1983	bool release = true;
1984	struct sock *sk;
1985
1986	if (!ctx)
1987		return;
1988
1989	sk = ctx->conn;
1990	if (sk) {
1991		/* if the msk has been orphaned, keep the ctx
1992		 * alive, will be freed by __mptcp_close_ssk(),
1993		 * when the subflow is still unaccepted
1994		 */
1995		release = ctx->disposable || list_empty(&ctx->node);
1996
1997		/* inet_child_forget() does not call sk_state_change(),
1998		 * explicitly trigger the socket close machinery
1999		 */
2000		if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
2001						  &mptcp_sk(sk)->flags))
2002			mptcp_schedule_work(sk);
2003		sock_put(sk);
2004	}
2005
2006	mptcp_subflow_ops_undo_override(ssk);
2007	if (release)
2008		kfree_rcu(ctx, rcu);
2009}
2010
2011static void subflow_ulp_clone(const struct request_sock *req,
2012			      struct sock *newsk,
2013			      const gfp_t priority)
2014{
2015	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2016	struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
2017	struct mptcp_subflow_context *new_ctx;
2018
2019	if (!tcp_rsk(req)->is_mptcp ||
2020	    (!subflow_req->mp_capable && !subflow_req->mp_join)) {
2021		subflow_ulp_fallback(newsk, old_ctx);
2022		return;
2023	}
2024
2025	new_ctx = subflow_create_ctx(newsk, priority);
2026	if (!new_ctx) {
2027		subflow_ulp_fallback(newsk, old_ctx);
2028		return;
2029	}
2030
2031	new_ctx->conn_finished = 1;
2032	new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
2033	new_ctx->tcp_state_change = old_ctx->tcp_state_change;
2034	new_ctx->tcp_error_report = old_ctx->tcp_error_report;
2035	new_ctx->rel_write_seq = 1;
 
2036
2037	if (subflow_req->mp_capable) {
2038		/* see comments in subflow_syn_recv_sock(), MPTCP connection
2039		 * is fully established only after we receive the remote key
2040		 */
2041		new_ctx->mp_capable = 1;
2042		new_ctx->local_key = subflow_req->local_key;
2043		new_ctx->token = subflow_req->token;
2044		new_ctx->ssn_offset = subflow_req->ssn_offset;
2045		new_ctx->idsn = subflow_req->idsn;
2046
2047		/* this is the first subflow, id is always 0 */
2048		subflow_set_local_id(new_ctx, 0);
2049	} else if (subflow_req->mp_join) {
2050		new_ctx->ssn_offset = subflow_req->ssn_offset;
2051		new_ctx->mp_join = 1;
2052		WRITE_ONCE(new_ctx->fully_established, true);
2053		new_ctx->remote_key_valid = 1;
2054		new_ctx->backup = subflow_req->backup;
2055		new_ctx->request_bkup = subflow_req->request_bkup;
2056		WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
2057		new_ctx->token = subflow_req->token;
2058		new_ctx->thmac = subflow_req->thmac;
2059
2060		/* the subflow req id is valid, fetched via subflow_check_req()
2061		 * and subflow_token_join_request()
2062		 */
2063		subflow_set_local_id(new_ctx, subflow_req->local_id);
2064	}
2065}
2066
2067static void tcp_release_cb_override(struct sock *ssk)
2068{
2069	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2070	long status;
2071
2072	/* process and clear all the pending actions, but leave the subflow into
2073	 * the napi queue. To respect locking, only the same CPU that originated
2074	 * the action can touch the list. mptcp_napi_poll will take care of it.
2075	 */
2076	status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
2077	if (status)
2078		mptcp_subflow_process_delegated(ssk, status);
2079
2080	tcp_release_cb(ssk);
2081}
2082
2083static int tcp_abort_override(struct sock *ssk, int err)
2084{
2085	/* closing a listener subflow requires a great deal of care.
2086	 * keep it simple and just prevent such operation
2087	 */
2088	if (inet_sk_state_load(ssk) == TCP_LISTEN)
2089		return -EINVAL;
2090
2091	return tcp_abort(ssk, err);
2092}
2093
2094static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
2095	.name		= "mptcp",
2096	.owner		= THIS_MODULE,
2097	.init		= subflow_ulp_init,
2098	.release	= subflow_ulp_release,
2099	.clone		= subflow_ulp_clone,
2100};
2101
2102static int subflow_ops_init(struct request_sock_ops *subflow_ops)
2103{
2104	subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
2105
2106	subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
2107					      subflow_ops->obj_size, 0,
2108					      SLAB_ACCOUNT |
2109					      SLAB_TYPESAFE_BY_RCU,
2110					      NULL);
2111	if (!subflow_ops->slab)
2112		return -ENOMEM;
2113
2114	return 0;
2115}
2116
2117void __init mptcp_subflow_init(void)
2118{
2119	mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
2120	mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
2121	mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
2122
2123	if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
2124		panic("MPTCP: failed to init subflow v4 request sock ops\n");
2125
2126	subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
2127	subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
2128	subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
2129
2130	subflow_specific = ipv4_specific;
2131	subflow_specific.conn_request = subflow_v4_conn_request;
2132	subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
2133	subflow_specific.sk_rx_dst_set = subflow_finish_connect;
2134	subflow_specific.rebuild_header = subflow_rebuild_header;
2135
2136	tcp_prot_override = tcp_prot;
2137	tcp_prot_override.release_cb = tcp_release_cb_override;
2138	tcp_prot_override.diag_destroy = tcp_abort_override;
2139
2140#if IS_ENABLED(CONFIG_MPTCP_IPV6)
2141	/* In struct mptcp_subflow_request_sock, we assume the TCP request sock
2142	 * structures for v4 and v6 have the same size. It should not changed in
2143	 * the future but better to make sure to be warned if it is no longer
2144	 * the case.
2145	 */
2146	BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
2147
2148	mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
2149	mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
2150	mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
2151
2152	if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
2153		panic("MPTCP: failed to init subflow v6 request sock ops\n");
2154
2155	subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
2156	subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
2157	subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
2158
2159	subflow_v6_specific = ipv6_specific;
2160	subflow_v6_specific.conn_request = subflow_v6_conn_request;
2161	subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
2162	subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
2163	subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
2164
2165	subflow_v6m_specific = subflow_v6_specific;
2166	subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
2167	subflow_v6m_specific.send_check = ipv4_specific.send_check;
2168	subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
2169	subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
 
2170	subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
2171
2172	tcpv6_prot_override = tcpv6_prot;
2173	tcpv6_prot_override.release_cb = tcp_release_cb_override;
2174	tcpv6_prot_override.diag_destroy = tcp_abort_override;
2175#endif
2176
2177	mptcp_diag_subflow_init(&subflow_ulp_ops);
2178
2179	if (tcp_register_ulp(&subflow_ulp_ops) != 0)
2180		panic("MPTCP: failed to register subflows to ULP\n");
2181}