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 <crypto/sha2.h>
  11#include <net/tcp.h>
  12#include <net/mptcp.h>
  13#include "protocol.h"
  14#include "mib.h"
  15
  16#include <trace/events/mptcp.h>
  17
  18static bool mptcp_cap_flag_sha256(u8 flags)
  19{
  20	return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
  21}
  22
  23static void mptcp_parse_option(const struct sk_buff *skb,
  24			       const unsigned char *ptr, int opsize,
  25			       struct mptcp_options_received *mp_opt)
  26{
  27	u8 subtype = *ptr >> 4;
  28	int expected_opsize;
 
  29	u8 version;
  30	u8 flags;
  31	u8 i;
  32
  33	switch (subtype) {
  34	case MPTCPOPT_MP_CAPABLE:
  35		/* strict size checking */
  36		if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
  37			if (skb->len > tcp_hdr(skb)->doff << 2)
  38				expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
  39			else
  40				expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
 
  41		} else {
  42			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
  43				expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
  44			else
 
  45				expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
 
 
  46		}
  47
  48		/* Cfr RFC 8684 Section 3.3.0:
  49		 * If a checksum is present but its use had
  50		 * not been negotiated in the MP_CAPABLE handshake, the receiver MUST
  51		 * close the subflow with a RST, as it is not behaving as negotiated.
  52		 * If a checksum is not present when its use has been negotiated, the
  53		 * receiver MUST close the subflow with a RST, as it is considered
  54		 * broken
  55		 * We parse even option with mismatching csum presence, so that
  56		 * later in subflow_data_ready we can trigger the reset.
  57		 */
  58		if (opsize != expected_opsize &&
  59		    (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA ||
  60		     opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM))
  61			break;
  62
  63		/* try to be gentle vs future versions on the initial syn */
  64		version = *ptr++ & MPTCP_VERSION_MASK;
  65		if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
  66			if (version != MPTCP_SUPPORTED_VERSION)
  67				break;
  68		} else if (version < MPTCP_SUPPORTED_VERSION) {
  69			break;
  70		}
  71
  72		flags = *ptr++;
  73		if (!mptcp_cap_flag_sha256(flags) ||
  74		    (flags & MPTCP_CAP_EXTENSIBILITY))
  75			break;
  76
  77		/* RFC 6824, Section 3.1:
  78		 * "For the Checksum Required bit (labeled "A"), if either
  79		 * host requires the use of checksums, checksums MUST be used.
  80		 * In other words, the only way for checksums not to be used
  81		 * is if both hosts in their SYNs set A=0."
  82		 */
  83		if (flags & MPTCP_CAP_CHECKSUM_REQD)
  84			mp_opt->csum_reqd = 1;
  85
  86		if (flags & MPTCP_CAP_DENY_JOIN_ID0)
  87			mp_opt->deny_join_id0 = 1;
  88
  89		mp_opt->mp_capable = 1;
  90		if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
  91			mp_opt->sndr_key = get_unaligned_be64(ptr);
  92			ptr += 8;
  93		}
  94		if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
  95			mp_opt->rcvr_key = get_unaligned_be64(ptr);
  96			ptr += 8;
  97		}
  98		if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) {
  99			/* Section 3.1.:
 100			 * "the data parameters in a MP_CAPABLE are semantically
 101			 * equivalent to those in a DSS option and can be used
 102			 * interchangeably."
 103			 */
 104			mp_opt->dss = 1;
 105			mp_opt->use_map = 1;
 106			mp_opt->mpc_map = 1;
 
 107			mp_opt->data_len = get_unaligned_be16(ptr);
 108			ptr += 2;
 109		}
 110		if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) {
 111			mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr);
 112			mp_opt->csum_reqd = 1;
 113			ptr += 2;
 114		}
 115		pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u",
 116			 version, flags, opsize, mp_opt->sndr_key,
 117			 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum);
 118		break;
 119
 120	case MPTCPOPT_MP_JOIN:
 121		mp_opt->mp_join = 1;
 122		if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
 
 123			mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 124			mp_opt->join_id = *ptr++;
 125			mp_opt->token = get_unaligned_be32(ptr);
 126			ptr += 4;
 127			mp_opt->nonce = get_unaligned_be32(ptr);
 128			ptr += 4;
 129			pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
 130				 mp_opt->backup, mp_opt->join_id,
 131				 mp_opt->token, mp_opt->nonce);
 132		} else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
 
 133			mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
 134			mp_opt->join_id = *ptr++;
 135			mp_opt->thmac = get_unaligned_be64(ptr);
 136			ptr += 8;
 137			mp_opt->nonce = get_unaligned_be32(ptr);
 138			ptr += 4;
 139			pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
 140				 mp_opt->backup, mp_opt->join_id,
 141				 mp_opt->thmac, mp_opt->nonce);
 142		} else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
 
 143			ptr += 2;
 144			memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
 145			pr_debug("MP_JOIN hmac");
 146		} else {
 147			mp_opt->mp_join = 0;
 148		}
 149		break;
 150
 151	case MPTCPOPT_DSS:
 152		pr_debug("DSS");
 153		ptr++;
 154
 155		/* we must clear 'mpc_map' be able to detect MP_CAPABLE
 156		 * map vs DSS map in mptcp_incoming_options(), and reconstruct
 157		 * map info accordingly
 158		 */
 159		mp_opt->mpc_map = 0;
 160		flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
 161		mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
 162		mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
 163		mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
 164		mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
 165		mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
 166
 167		pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
 168			 mp_opt->data_fin, mp_opt->dsn64,
 169			 mp_opt->use_map, mp_opt->ack64,
 170			 mp_opt->use_ack);
 171
 172		expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
 173
 174		if (mp_opt->use_ack) {
 175			if (mp_opt->ack64)
 176				expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
 177			else
 178				expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
 179		}
 180
 181		if (mp_opt->use_map) {
 182			if (mp_opt->dsn64)
 183				expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
 184			else
 185				expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
 186		}
 187
 188		/* Always parse any csum presence combination, we will enforce
 189		 * RFC 8684 Section 3.3.0 checks later in subflow_data_ready
 190		 */
 191		if (opsize != expected_opsize &&
 192		    opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
 193			break;
 194
 195		mp_opt->dss = 1;
 196
 197		if (mp_opt->use_ack) {
 198			if (mp_opt->ack64) {
 199				mp_opt->data_ack = get_unaligned_be64(ptr);
 200				ptr += 8;
 201			} else {
 202				mp_opt->data_ack = get_unaligned_be32(ptr);
 203				ptr += 4;
 204			}
 205
 206			pr_debug("data_ack=%llu", mp_opt->data_ack);
 207		}
 208
 209		if (mp_opt->use_map) {
 210			if (mp_opt->dsn64) {
 211				mp_opt->data_seq = get_unaligned_be64(ptr);
 212				ptr += 8;
 213			} else {
 214				mp_opt->data_seq = get_unaligned_be32(ptr);
 215				ptr += 4;
 216			}
 217
 218			mp_opt->subflow_seq = get_unaligned_be32(ptr);
 219			ptr += 4;
 220
 221			mp_opt->data_len = get_unaligned_be16(ptr);
 222			ptr += 2;
 223
 224			if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) {
 225				mp_opt->csum_reqd = 1;
 226				mp_opt->csum = (__force __sum16)get_unaligned_be16(ptr);
 227				ptr += 2;
 228			}
 229
 230			pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
 231				 mp_opt->data_seq, mp_opt->subflow_seq,
 232				 mp_opt->data_len, mp_opt->csum_reqd, mp_opt->csum);
 
 233		}
 234
 235		break;
 236
 237	case MPTCPOPT_ADD_ADDR:
 238		mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
 239		if (!mp_opt->echo) {
 240			if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
 241			    opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
 242				mp_opt->addr.family = AF_INET;
 243#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 244			else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
 245				 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
 246				mp_opt->addr.family = AF_INET6;
 247#endif
 248			else
 249				break;
 250		} else {
 251			if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
 252			    opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
 253				mp_opt->addr.family = AF_INET;
 254#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 255			else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
 256				 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
 257				mp_opt->addr.family = AF_INET6;
 258#endif
 259			else
 260				break;
 261		}
 262
 263		mp_opt->add_addr = 1;
 264		mp_opt->addr.id = *ptr++;
 
 
 265		if (mp_opt->addr.family == AF_INET) {
 266			memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);
 267			ptr += 4;
 268			if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
 269			    opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
 270				mp_opt->addr.port = htons(get_unaligned_be16(ptr));
 271				ptr += 2;
 272			}
 273		}
 274#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 275		else {
 276			memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16);
 277			ptr += 16;
 278			if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
 279			    opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
 280				mp_opt->addr.port = htons(get_unaligned_be16(ptr));
 281				ptr += 2;
 282			}
 283		}
 284#endif
 285		if (!mp_opt->echo) {
 286			mp_opt->ahmac = get_unaligned_be64(ptr);
 287			ptr += 8;
 288		}
 289		pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
 290			 (mp_opt->addr.family == AF_INET6) ? "6" : "",
 291			 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port));
 292		break;
 293
 294	case MPTCPOPT_RM_ADDR:
 295		if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 ||
 296		    opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX)
 297			break;
 298
 299		ptr++;
 300
 301		mp_opt->rm_addr = 1;
 302		mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;
 303		for (i = 0; i < mp_opt->rm_list.nr; i++)
 304			mp_opt->rm_list.ids[i] = *ptr++;
 305		pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr);
 306		break;
 307
 308	case MPTCPOPT_MP_PRIO:
 309		if (opsize != TCPOLEN_MPTCP_PRIO)
 310			break;
 311
 312		mp_opt->mp_prio = 1;
 313		mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
 314		pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
 315		break;
 316
 317	case MPTCPOPT_MP_FASTCLOSE:
 318		if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
 319			break;
 320
 321		ptr += 2;
 322		mp_opt->rcvr_key = get_unaligned_be64(ptr);
 323		ptr += 8;
 324		mp_opt->fastclose = 1;
 
 325		break;
 326
 327	case MPTCPOPT_RST:
 328		if (opsize != TCPOLEN_MPTCP_RST)
 329			break;
 330
 331		if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
 332			break;
 333		mp_opt->reset = 1;
 
 334		flags = *ptr++;
 335		mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
 336		mp_opt->reset_reason = *ptr;
 
 
 
 
 
 
 
 
 
 
 
 
 337		break;
 338
 339	default:
 340		break;
 341	}
 342}
 343
 344void mptcp_get_options(const struct sock *sk,
 345		       const struct sk_buff *skb,
 346		       struct mptcp_options_received *mp_opt)
 347{
 348	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 349	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 350	const struct tcphdr *th = tcp_hdr(skb);
 351	const unsigned char *ptr;
 352	int length;
 353
 354	/* initialize option status */
 355	mp_opt->mp_capable = 0;
 356	mp_opt->mp_join = 0;
 357	mp_opt->add_addr = 0;
 358	mp_opt->ahmac = 0;
 359	mp_opt->fastclose = 0;
 360	mp_opt->addr.port = 0;
 361	mp_opt->rm_addr = 0;
 362	mp_opt->dss = 0;
 363	mp_opt->mp_prio = 0;
 364	mp_opt->reset = 0;
 365	mp_opt->csum_reqd = READ_ONCE(msk->csum_enabled);
 366	mp_opt->deny_join_id0 = 0;
 367
 368	length = (th->doff * 4) - sizeof(struct tcphdr);
 369	ptr = (const unsigned char *)(th + 1);
 370
 371	while (length > 0) {
 372		int opcode = *ptr++;
 373		int opsize;
 374
 375		switch (opcode) {
 376		case TCPOPT_EOL:
 377			return;
 378		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
 379			length--;
 380			continue;
 381		default:
 382			if (length < 2)
 383				return;
 384			opsize = *ptr++;
 385			if (opsize < 2) /* "silly options" */
 386				return;
 387			if (opsize > length)
 388				return;	/* don't parse partial options */
 389			if (opcode == TCPOPT_MPTCP)
 390				mptcp_parse_option(skb, ptr, opsize, mp_opt);
 391			ptr += opsize - 2;
 392			length -= opsize;
 393		}
 394	}
 395}
 396
 397bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 398		       unsigned int *size, struct mptcp_out_options *opts)
 399{
 400	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 401
 402	/* we will use snd_isn to detect first pkt [re]transmission
 403	 * in mptcp_established_options_mp()
 404	 */
 405	subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 406	if (subflow->request_mptcp) {
 407		opts->suboptions = OPTION_MPTCP_MPC_SYN;
 408		opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk));
 409		opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
 410		*size = TCPOLEN_MPTCP_MPC_SYN;
 411		return true;
 412	} else if (subflow->request_join) {
 413		pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
 414			 subflow->local_nonce);
 415		opts->suboptions = OPTION_MPTCP_MPJ_SYN;
 416		opts->join_id = subflow->local_id;
 417		opts->token = subflow->remote_token;
 418		opts->nonce = subflow->local_nonce;
 419		opts->backup = subflow->request_bkup;
 420		*size = TCPOLEN_MPTCP_MPJ_SYN;
 421		return true;
 422	}
 423	return false;
 424}
 425
 426/* MP_JOIN client subflow must wait for 4th ack before sending any data:
 427 * TCP can't schedule delack timer before the subflow is fully established.
 428 * MPTCP uses the delack timer to do 3rd ack retransmissions
 429 */
 430static void schedule_3rdack_retransmission(struct sock *sk)
 431{
 432	struct inet_connection_sock *icsk = inet_csk(sk);
 433	struct tcp_sock *tp = tcp_sk(sk);
 434	unsigned long timeout;
 435
 436	/* reschedule with a timeout above RTT, as we must look only for drop */
 437	if (tp->srtt_us)
 438		timeout = tp->srtt_us << 1;
 439	else
 440		timeout = TCP_TIMEOUT_INIT;
 441
 442	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
 443	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
 444	icsk->icsk_ack.timeout = timeout;
 445	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
 446}
 447
 448static void clear_3rdack_retransmission(struct sock *sk)
 449{
 450	struct inet_connection_sock *icsk = inet_csk(sk);
 451
 452	sk_stop_timer(sk, &icsk->icsk_delack_timer);
 453	icsk->icsk_ack.timeout = 0;
 454	icsk->icsk_ack.ato = 0;
 455	icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
 456}
 457
 458static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 459					 bool snd_data_fin_enable,
 460					 unsigned int *size,
 461					 unsigned int remaining,
 462					 struct mptcp_out_options *opts)
 463{
 464	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 465	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 466	struct mptcp_ext *mpext;
 467	unsigned int data_len;
 468	u8 len;
 469
 470	/* When skb is not available, we better over-estimate the emitted
 471	 * options len. A full DSS option (28 bytes) is longer than
 472	 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
 473	 * tell the caller to defer the estimate to
 474	 * mptcp_established_options_dss(), which will reserve enough space.
 475	 */
 476	if (!skb)
 477		return false;
 478
 479	/* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
 480	if (subflow->fully_established || snd_data_fin_enable ||
 481	    subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
 482	    sk->sk_state != TCP_ESTABLISHED)
 483		return false;
 484
 485	if (subflow->mp_capable) {
 486		mpext = mptcp_get_ext(skb);
 487		data_len = mpext ? mpext->data_len : 0;
 488
 489		/* we will check ext_copy.data_len in mptcp_write_options() to
 490		 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
 491		 * TCPOLEN_MPTCP_MPC_ACK
 492		 */
 493		opts->ext_copy.data_len = data_len;
 494		opts->suboptions = OPTION_MPTCP_MPC_ACK;
 495		opts->sndr_key = subflow->local_key;
 496		opts->rcvr_key = subflow->remote_key;
 497		opts->csum_reqd = READ_ONCE(msk->csum_enabled);
 498		opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
 499
 500		/* Section 3.1.
 501		 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
 502		 * packets that start the first subflow of an MPTCP connection,
 503		 * as well as the first packet that carries data
 504		 */
 505		if (data_len > 0) {
 506			len = TCPOLEN_MPTCP_MPC_ACK_DATA;
 507			if (opts->csum_reqd) {
 508				/* we need to propagate more info to csum the pseudo hdr */
 509				opts->ext_copy.data_seq = mpext->data_seq;
 510				opts->ext_copy.subflow_seq = mpext->subflow_seq;
 511				opts->ext_copy.csum = mpext->csum;
 512				len += TCPOLEN_MPTCP_DSS_CHECKSUM;
 513			}
 514			*size = ALIGN(len, 4);
 515		} else {
 516			*size = TCPOLEN_MPTCP_MPC_ACK;
 517		}
 518
 519		pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
 520			 subflow, subflow->local_key, subflow->remote_key,
 521			 data_len);
 522
 523		return true;
 524	} else if (subflow->mp_join) {
 525		opts->suboptions = OPTION_MPTCP_MPJ_ACK;
 526		memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
 527		*size = TCPOLEN_MPTCP_MPJ_ACK;
 528		pr_debug("subflow=%p", subflow);
 529
 530		schedule_3rdack_retransmission(sk);
 
 
 
 
 
 
 
 
 531		return true;
 532	}
 533	return false;
 534}
 535
 536static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
 537				 struct sk_buff *skb, struct mptcp_ext *ext)
 538{
 539	/* The write_seq value has already been incremented, so the actual
 540	 * sequence number for the DATA_FIN is one less.
 541	 */
 542	u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
 543
 544	if (!ext->use_map || !skb->len) {
 545		/* RFC6824 requires a DSS mapping with specific values
 546		 * if DATA_FIN is set but no data payload is mapped
 547		 */
 548		ext->data_fin = 1;
 549		ext->use_map = 1;
 550		ext->dsn64 = 1;
 551		ext->data_seq = data_fin_tx_seq;
 552		ext->subflow_seq = 0;
 553		ext->data_len = 1;
 554	} else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
 555		/* If there's an existing DSS mapping and it is the
 556		 * final mapping, DATA_FIN consumes 1 additional byte of
 557		 * mapping space.
 558		 */
 559		ext->data_fin = 1;
 560		ext->data_len++;
 561	}
 562}
 563
 564static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 565					  bool snd_data_fin_enable,
 566					  unsigned int *size,
 567					  unsigned int remaining,
 568					  struct mptcp_out_options *opts)
 569{
 570	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 571	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 572	unsigned int dss_size = 0;
 573	struct mptcp_ext *mpext;
 574	unsigned int ack_size;
 575	bool ret = false;
 576	u64 ack_seq;
 577
 578	opts->csum_reqd = READ_ONCE(msk->csum_enabled);
 579	mpext = skb ? mptcp_get_ext(skb) : NULL;
 580
 581	if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
 582		unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
 583
 584		if (mpext) {
 585			if (opts->csum_reqd)
 586				map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;
 587
 588			opts->ext_copy = *mpext;
 589		}
 590
 591		remaining -= map_size;
 592		dss_size = map_size;
 593		if (skb && snd_data_fin_enable)
 594			mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
 
 595		ret = true;
 596	}
 597
 598	/* passive sockets msk will set the 'can_ack' after accept(), even
 599	 * if the first subflow may have the already the remote key handy
 600	 */
 601	opts->ext_copy.use_ack = 0;
 602	if (!READ_ONCE(msk->can_ack)) {
 603		*size = ALIGN(dss_size, 4);
 604		return ret;
 605	}
 606
 607	ack_seq = READ_ONCE(msk->ack_seq);
 608	if (READ_ONCE(msk->use_64bit_ack)) {
 609		ack_size = TCPOLEN_MPTCP_DSS_ACK64;
 610		opts->ext_copy.data_ack = ack_seq;
 611		opts->ext_copy.ack64 = 1;
 612	} else {
 613		ack_size = TCPOLEN_MPTCP_DSS_ACK32;
 614		opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
 615		opts->ext_copy.ack64 = 0;
 616	}
 617	opts->ext_copy.use_ack = 1;
 
 618	WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
 619
 620	/* Add kind/length/subtype/flag overhead if mapping is not populated */
 621	if (dss_size == 0)
 622		ack_size += TCPOLEN_MPTCP_DSS_BASE;
 623
 624	dss_size += ack_size;
 625
 626	*size = ALIGN(dss_size, 4);
 627	return true;
 628}
 629
 630static u64 add_addr_generate_hmac(u64 key1, u64 key2,
 631				  struct mptcp_addr_info *addr)
 632{
 633	u16 port = ntohs(addr->port);
 634	u8 hmac[SHA256_DIGEST_SIZE];
 635	u8 msg[19];
 636	int i = 0;
 637
 638	msg[i++] = addr->id;
 639	if (addr->family == AF_INET) {
 640		memcpy(&msg[i], &addr->addr.s_addr, 4);
 641		i += 4;
 642	}
 643#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 644	else if (addr->family == AF_INET6) {
 645		memcpy(&msg[i], &addr->addr6.s6_addr, 16);
 646		i += 16;
 647	}
 648#endif
 649	msg[i++] = port >> 8;
 650	msg[i++] = port & 0xFF;
 651
 652	mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac);
 653
 654	return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
 655}
 656
 657static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
 658					       unsigned int *size,
 659					       unsigned int remaining,
 660					       struct mptcp_out_options *opts)
 661{
 662	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 663	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 664	bool drop_other_suboptions = false;
 665	unsigned int opt_size = *size;
 666	bool echo;
 667	bool port;
 668	int len;
 669
 670	if ((mptcp_pm_should_add_signal_ipv6(msk) ||
 671	     mptcp_pm_should_add_signal_port(msk) ||
 672	     mptcp_pm_should_add_signal_echo(msk)) &&
 673	    skb && skb_is_tcp_pure_ack(skb)) {
 674		pr_debug("drop other suboptions");
 675		opts->suboptions = 0;
 676		opts->ext_copy.use_ack = 0;
 677		opts->ext_copy.use_map = 0;
 678		remaining += opt_size;
 679		drop_other_suboptions = true;
 680	}
 681
 682	if (!mptcp_pm_should_add_signal(msk) ||
 683	    !(mptcp_pm_add_addr_signal(msk, remaining, &opts->addr, &echo, &port)))
 
 
 684		return false;
 685
 686	len = mptcp_add_addr_len(opts->addr.family, echo, port);
 
 
 687	if (remaining < len)
 688		return false;
 689
 690	*size = len;
 691	if (drop_other_suboptions)
 
 
 
 
 
 
 
 
 
 692		*size -= opt_size;
 
 693	opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
 694	if (!echo) {
 
 695		opts->ahmac = add_addr_generate_hmac(msk->local_key,
 696						     msk->remote_key,
 697						     &opts->addr);
 
 
 698	}
 699	pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
 700		 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
 701
 702	return true;
 703}
 704
 705static bool mptcp_established_options_rm_addr(struct sock *sk,
 706					      unsigned int *size,
 707					      unsigned int remaining,
 708					      struct mptcp_out_options *opts)
 709{
 710	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 711	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 712	struct mptcp_rm_list rm_list;
 713	int i, len;
 714
 715	if (!mptcp_pm_should_rm_signal(msk) ||
 716	    !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list)))
 717		return false;
 718
 719	len = mptcp_rm_addr_len(&rm_list);
 720	if (len < 0)
 721		return false;
 722	if (remaining < len)
 723		return false;
 724
 725	*size = len;
 726	opts->suboptions |= OPTION_MPTCP_RM_ADDR;
 727	opts->rm_list = rm_list;
 728
 729	for (i = 0; i < opts->rm_list.nr; i++)
 730		pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]);
 731
 732	return true;
 733}
 734
 735static bool mptcp_established_options_mp_prio(struct sock *sk,
 736					      unsigned int *size,
 737					      unsigned int remaining,
 738					      struct mptcp_out_options *opts)
 739{
 740	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 741
 742	if (!subflow->send_mp_prio)
 
 
 
 743		return false;
 744
 745	/* account for the trailing 'nop' option */
 746	if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
 747		return false;
 748
 749	*size = TCPOLEN_MPTCP_PRIO_ALIGN;
 750	opts->suboptions |= OPTION_MPTCP_PRIO;
 751	opts->backup = subflow->request_bkup;
 752
 753	pr_debug("prio=%d", opts->backup);
 754
 755	return true;
 756}
 757
 758static noinline void mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
 759						   unsigned int *size,
 760						   unsigned int remaining,
 761						   struct mptcp_out_options *opts)
 762{
 763	const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 764
 765	if (remaining < TCPOLEN_MPTCP_RST)
 766		return;
 767
 768	*size = TCPOLEN_MPTCP_RST;
 769	opts->suboptions |= OPTION_MPTCP_RST;
 770	opts->reset_transient = subflow->reset_transient;
 771	opts->reset_reason = subflow->reset_reason;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 772}
 773
 774bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 775			       unsigned int *size, unsigned int remaining,
 776			       struct mptcp_out_options *opts)
 777{
 778	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 779	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 780	unsigned int opt_size = 0;
 781	bool snd_data_fin;
 782	bool ret = false;
 783
 784	opts->suboptions = 0;
 785
 786	if (unlikely(__mptcp_check_fallback(msk)))
 787		return false;
 788
 789	if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
 790		mptcp_established_options_rst(sk, skb, size, remaining, opts);
 
 
 
 
 
 
 
 
 
 791		return true;
 792	}
 793
 794	snd_data_fin = mptcp_data_fin_enabled(msk);
 795	if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
 796		ret = true;
 797	else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts))
 
 
 798		ret = true;
 
 
 
 
 
 
 
 799
 800	/* we reserved enough space for the above options, and exceeding the
 801	 * TCP option space would be fatal
 802	 */
 803	if (WARN_ON_ONCE(opt_size > remaining))
 804		return false;
 805
 806	*size += opt_size;
 807	remaining -= opt_size;
 808	if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
 809		*size += opt_size;
 810		remaining -= opt_size;
 811		ret = true;
 812	} else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
 813		*size += opt_size;
 814		remaining -= opt_size;
 815		ret = true;
 816	}
 817
 818	if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
 819		*size += opt_size;
 820		remaining -= opt_size;
 821		ret = true;
 822	}
 823
 824	return ret;
 825}
 826
 827bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 828			  struct mptcp_out_options *opts)
 829{
 830	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
 831
 832	if (subflow_req->mp_capable) {
 833		opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 834		opts->sndr_key = subflow_req->local_key;
 835		opts->csum_reqd = subflow_req->csum_reqd;
 836		opts->allow_join_id0 = subflow_req->allow_join_id0;
 837		*size = TCPOLEN_MPTCP_MPC_SYNACK;
 838		pr_debug("subflow_req=%p, local_key=%llu",
 839			 subflow_req, subflow_req->local_key);
 840		return true;
 841	} else if (subflow_req->mp_join) {
 842		opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
 843		opts->backup = subflow_req->backup;
 844		opts->join_id = subflow_req->local_id;
 845		opts->thmac = subflow_req->thmac;
 846		opts->nonce = subflow_req->local_nonce;
 847		pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
 848			 subflow_req, opts->backup, opts->join_id,
 849			 opts->thmac, opts->nonce);
 850		*size = TCPOLEN_MPTCP_MPJ_SYNACK;
 851		return true;
 852	}
 853	return false;
 854}
 855
 856static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 857				    struct mptcp_subflow_context *subflow,
 858				    struct sk_buff *skb,
 859				    struct mptcp_options_received *mp_opt)
 860{
 861	/* here we can process OoO, in-window pkts, only in-sequence 4th ack
 862	 * will make the subflow fully established
 863	 */
 864	if (likely(subflow->fully_established)) {
 865		/* on passive sockets, check for 3rd ack retransmission
 866		 * note that msk is always set by subflow_syn_recv_sock()
 867		 * for mp_join subflows
 868		 */
 869		if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
 870		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
 871		    subflow->mp_join && mp_opt->mp_join &&
 872		    READ_ONCE(msk->pm.server_side))
 873			tcp_send_ack(ssk);
 874		goto fully_established;
 875	}
 876
 877	/* we must process OoO packets before the first subflow is fully
 878	 * established. OoO packets are instead a protocol violation
 879	 * for MP_JOIN subflows as the peer must not send any data
 880	 * before receiving the forth ack - cfr. RFC 8684 section 3.2.
 881	 */
 882	if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
 883		if (subflow->mp_join)
 884			goto reset;
 
 
 885		return subflow->mp_capable;
 886	}
 887
 888	if ((mp_opt->dss && mp_opt->use_ack) ||
 889	    (mp_opt->add_addr && !mp_opt->echo)) {
 
 890		/* subflows are fully established as soon as we get any
 891		 * additional ack, including ADD_ADDR.
 892		 */
 893		subflow->fully_established = 1;
 894		WRITE_ONCE(msk->fully_established, true);
 895		goto fully_established;
 896	}
 897
 898	/* If the first established packet does not contain MP_CAPABLE + data
 899	 * then fallback to TCP. Fallback scenarios requires a reset for
 900	 * MP_JOIN subflows.
 901	 */
 902	if (!mp_opt->mp_capable) {
 903		if (subflow->mp_join)
 904			goto reset;
 905		subflow->mp_capable = 0;
 906		pr_fallback(msk);
 907		__mptcp_do_fallback(msk);
 908		return false;
 909	}
 910
 911	if (mp_opt->deny_join_id0)
 912		WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
 913
 914	if (unlikely(!READ_ONCE(msk->pm.server_side)))
 915		pr_warn_once("bogus mpc option on established client sk");
 916	mptcp_subflow_fully_established(subflow, mp_opt);
 917
 918fully_established:
 
 
 
 
 
 919	/* if the subflow is not already linked into the conn_list, we can't
 920	 * notify the PM: this subflow is still on the listener queue
 921	 * and the PM possibly acquiring the subflow lock could race with
 922	 * the listener close
 923	 */
 924	if (likely(subflow->pm_notified) || list_empty(&subflow->node))
 925		return true;
 926
 927	subflow->pm_notified = 1;
 928	if (subflow->mp_join) {
 929		clear_3rdack_retransmission(ssk);
 930		mptcp_pm_subflow_established(msk);
 931	} else {
 932		mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC);
 933	}
 934	return true;
 935
 936reset:
 937	mptcp_subflow_reset(ssk);
 938	return false;
 939}
 940
 941u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq)
 942{
 943	u32 old_seq32, cur_seq32;
 944
 945	old_seq32 = (u32)old_seq;
 946	cur_seq32 = (u32)cur_seq;
 947	cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32;
 948	if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32)))
 949		return cur_seq + (1LL << 32);
 950
 951	/* reverse wrap could happen, too */
 952	if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32)))
 953		return cur_seq - (1LL << 32);
 954	return cur_seq;
 955}
 956
 
 
 
 
 
 
 957static void ack_update_msk(struct mptcp_sock *msk,
 958			   struct sock *ssk,
 959			   struct mptcp_options_received *mp_opt)
 960{
 961	u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
 962	struct sock *sk = (struct sock *)msk;
 963	u64 old_snd_una;
 964
 965	mptcp_data_lock(sk);
 966
 967	/* avoid ack expansion on update conflict, to reduce the risk of
 968	 * wrongly expanding to a future ack sequence number, which is way
 969	 * more dangerous than missing an ack
 970	 */
 971	old_snd_una = msk->snd_una;
 972	new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
 973
 974	/* ACK for data not even sent yet? Ignore. */
 975	if (after64(new_snd_una, snd_nxt))
 976		new_snd_una = old_snd_una;
 977
 978	new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
 979
 980	if (after64(new_wnd_end, msk->wnd_end))
 981		msk->wnd_end = new_wnd_end;
 982
 983	/* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
 984	if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
 985		__mptcp_check_push(sk, ssk);
 986
 987	if (after64(new_snd_una, old_snd_una)) {
 988		msk->snd_una = new_snd_una;
 989		__mptcp_data_acked(sk);
 990	}
 991	mptcp_data_unlock(sk);
 992
 993	trace_ack_update_msk(mp_opt->data_ack,
 994			     old_snd_una, new_snd_una,
 995			     new_wnd_end, msk->wnd_end);
 996}
 997
 998bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
 999{
1000	/* Skip if DATA_FIN was already received.
1001	 * If updating simultaneously with the recvmsg loop, values
1002	 * should match. If they mismatch, the peer is misbehaving and
1003	 * we will prefer the most recent information.
1004	 */
1005	if (READ_ONCE(msk->rcv_data_fin))
1006		return false;
1007
1008	WRITE_ONCE(msk->rcv_data_fin_seq,
1009		   mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
1010	WRITE_ONCE(msk->rcv_data_fin, 1);
1011
1012	return true;
1013}
1014
1015static bool add_addr_hmac_valid(struct mptcp_sock *msk,
1016				struct mptcp_options_received *mp_opt)
1017{
1018	u64 hmac = 0;
1019
1020	if (mp_opt->echo)
1021		return true;
1022
1023	hmac = add_addr_generate_hmac(msk->remote_key,
1024				      msk->local_key,
1025				      &mp_opt->addr);
1026
1027	pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
1028		 msk, (unsigned long long)hmac,
1029		 (unsigned long long)mp_opt->ahmac);
1030
1031	return hmac == mp_opt->ahmac;
1032}
1033
1034/* Return false if a subflow has been reset, else return true */
1035bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
1036{
1037	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1038	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1039	struct mptcp_options_received mp_opt;
1040	struct mptcp_ext *mpext;
1041
1042	if (__mptcp_check_fallback(msk)) {
1043		/* Keep it simple and unconditionally trigger send data cleanup and
1044		 * pending queue spooling. We will need to acquire the data lock
1045		 * for more accurate checks, and once the lock is acquired, such
1046		 * helpers are cheap.
1047		 */
1048		mptcp_data_lock(subflow->conn);
1049		if (sk_stream_memory_free(sk))
1050			__mptcp_check_push(subflow->conn, sk);
 
 
 
 
 
 
1051		__mptcp_data_acked(subflow->conn);
1052		mptcp_data_unlock(subflow->conn);
1053		return true;
1054	}
1055
1056	mptcp_get_options(sk, skb, &mp_opt);
1057
1058	/* The subflow can be in close state only if check_fully_established()
1059	 * just sent a reset. If so, tell the caller to ignore the current packet.
1060	 */
1061	if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
1062		return sk->sk_state != TCP_CLOSE;
1063
1064	if (mp_opt.fastclose &&
1065	    msk->local_key == mp_opt.rcvr_key) {
1066		WRITE_ONCE(msk->rcv_fastclose, true);
1067		mptcp_schedule_work((struct sock *)msk);
1068	}
 
 
1069
1070	if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
1071		if (!mp_opt.echo) {
1072			mptcp_pm_add_addr_received(msk, &mp_opt.addr);
1073			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
1074		} else {
1075			mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);
1076			mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);
1077			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
 
 
 
 
 
1078		}
1079
1080		if (mp_opt.addr.port)
1081			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
1082
1083		mp_opt.add_addr = 0;
1084	}
 
 
1085
1086	if (mp_opt.rm_addr) {
1087		mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);
1088		mp_opt.rm_addr = 0;
1089	}
1090
1091	if (mp_opt.mp_prio) {
1092		mptcp_pm_mp_prio_received(sk, mp_opt.backup);
1093		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
1094		mp_opt.mp_prio = 0;
1095	}
 
1096
1097	if (mp_opt.reset) {
1098		subflow->reset_seen = 1;
1099		subflow->reset_reason = mp_opt.reset_reason;
1100		subflow->reset_transient = mp_opt.reset_transient;
1101	}
1102
1103	if (!mp_opt.dss)
1104		return true;
1105
1106	/* we can't wait for recvmsg() to update the ack_seq, otherwise
1107	 * monodirectional flows will stuck
1108	 */
1109	if (mp_opt.use_ack)
1110		ack_update_msk(msk, sk, &mp_opt);
1111
1112	/* Zero-data-length packets are dropped by the caller and not
1113	 * propagated to the MPTCP layer, so the skb extension does not
1114	 * need to be allocated or populated. DATA_FIN information, if
1115	 * present, needs to be updated here before the skb is freed.
1116	 */
1117	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
1118		if (mp_opt.data_fin && mp_opt.data_len == 1 &&
1119		    mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
1120		    schedule_work(&msk->work))
1121			sock_hold(subflow->conn);
1122
1123		return true;
1124	}
1125
1126	mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
1127	if (!mpext)
1128		return true;
1129
1130	memset(mpext, 0, sizeof(*mpext));
1131
1132	if (mp_opt.use_map) {
1133		if (mp_opt.mpc_map) {
1134			/* this is an MP_CAPABLE carrying MPTCP data
1135			 * we know this map the first chunk of data
1136			 */
1137			mptcp_crypto_key_sha(subflow->remote_key, NULL,
1138					     &mpext->data_seq);
1139			mpext->data_seq++;
1140			mpext->subflow_seq = 1;
1141			mpext->dsn64 = 1;
1142			mpext->mpc_map = 1;
1143			mpext->data_fin = 0;
1144		} else {
1145			mpext->data_seq = mp_opt.data_seq;
1146			mpext->subflow_seq = mp_opt.subflow_seq;
1147			mpext->dsn64 = mp_opt.dsn64;
1148			mpext->data_fin = mp_opt.data_fin;
1149		}
1150		mpext->data_len = mp_opt.data_len;
1151		mpext->use_map = 1;
1152		mpext->csum_reqd = mp_opt.csum_reqd;
1153
1154		if (mpext->csum_reqd)
1155			mpext->csum = mp_opt.csum;
1156	}
1157
1158	return true;
1159}
1160
1161static void mptcp_set_rwin(const struct tcp_sock *tp)
1162{
1163	const struct sock *ssk = (const struct sock *)tp;
1164	const struct mptcp_subflow_context *subflow;
 
1165	struct mptcp_sock *msk;
1166	u64 ack_seq;
 
1167
1168	subflow = mptcp_subflow_ctx(ssk);
1169	msk = mptcp_sk(subflow->conn);
1170
1171	ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
 
 
 
 
 
 
 
 
 
 
 
1172
1173	if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
1174		WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1175}
1176
1177static u16 mptcp_make_csum(const struct mptcp_ext *mpext)
1178{
1179	struct csum_pseudo_header header;
1180	__wsum csum;
1181
1182	/* cfr RFC 8684 3.3.1.:
1183	 * the data sequence number used in the pseudo-header is
1184	 * always the 64-bit value, irrespective of what length is used in the
1185	 * DSS option itself.
1186	 */
1187	header.data_seq = cpu_to_be64(mpext->data_seq);
1188	header.subflow_seq = htonl(mpext->subflow_seq);
1189	header.data_len = htons(mpext->data_len);
1190	header.csum = 0;
1191
1192	csum = csum_partial(&header, sizeof(header), ~csum_unfold(mpext->csum));
1193	return (__force u16)csum_fold(csum);
1194}
1195
1196void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1197			 struct mptcp_out_options *opts)
1198{
1199	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
1200	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1201		u8 len, flag = MPTCP_CAP_HMAC_SHA256;
1202
1203		if (OPTION_MPTCP_MPC_SYN & opts->suboptions) {
1204			len = TCPOLEN_MPTCP_MPC_SYN;
1205		} else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) {
1206			len = TCPOLEN_MPTCP_MPC_SYNACK;
1207		} else if (opts->ext_copy.data_len) {
1208			len = TCPOLEN_MPTCP_MPC_ACK_DATA;
1209			if (opts->csum_reqd)
1210				len += TCPOLEN_MPTCP_DSS_CHECKSUM;
1211		} else {
1212			len = TCPOLEN_MPTCP_MPC_ACK;
1213		}
1214
1215		if (opts->csum_reqd)
1216			flag |= MPTCP_CAP_CHECKSUM_REQD;
1217
1218		if (!opts->allow_join_id0)
1219			flag |= MPTCP_CAP_DENY_JOIN_ID0;
1220
1221		*ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
1222				      MPTCP_SUPPORTED_VERSION,
1223				      flag);
1224
1225		if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1226		    opts->suboptions))
1227			goto mp_capable_done;
1228
1229		put_unaligned_be64(opts->sndr_key, ptr);
1230		ptr += 2;
1231		if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1232			goto mp_capable_done;
1233
1234		put_unaligned_be64(opts->rcvr_key, ptr);
1235		ptr += 2;
1236		if (!opts->ext_copy.data_len)
1237			goto mp_capable_done;
1238
1239		if (opts->csum_reqd) {
1240			put_unaligned_be32(opts->ext_copy.data_len << 16 |
1241					   mptcp_make_csum(&opts->ext_copy), ptr);
 
 
 
 
1242		} else {
1243			put_unaligned_be32(opts->ext_copy.data_len << 16 |
1244					   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1245		}
1246		ptr += 1;
1247	}
1248
1249mp_capable_done:
1250	if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1251		u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
1252		u8 echo = MPTCP_ADDR_ECHO;
1253
1254#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1255		if (opts->addr.family == AF_INET6)
1256			len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
1257#endif
1258
1259		if (opts->addr.port)
1260			len += TCPOLEN_MPTCP_PORT_LEN;
1261
1262		if (opts->ahmac) {
1263			len += sizeof(opts->ahmac);
1264			echo = 0;
1265		}
1266
1267		*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1268				      len, echo, opts->addr.id);
1269		if (opts->addr.family == AF_INET) {
1270			memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4);
1271			ptr += 1;
1272		}
1273#if IS_ENABLED(CONFIG_MPTCP_IPV6)
1274		else if (opts->addr.family == AF_INET6) {
1275			memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16);
1276			ptr += 4;
1277		}
1278#endif
1279
1280		if (!opts->addr.port) {
1281			if (opts->ahmac) {
1282				put_unaligned_be64(opts->ahmac, ptr);
1283				ptr += 2;
1284			}
1285		} else {
1286			u16 port = ntohs(opts->addr.port);
1287
1288			if (opts->ahmac) {
1289				u8 *bptr = (u8 *)ptr;
1290
1291				put_unaligned_be16(port, bptr);
1292				bptr += 2;
1293				put_unaligned_be64(opts->ahmac, bptr);
1294				bptr += 8;
1295				put_unaligned_be16(TCPOPT_NOP << 8 |
1296						   TCPOPT_NOP, bptr);
1297
1298				ptr += 3;
1299			} else {
1300				put_unaligned_be32(port << 16 |
1301						   TCPOPT_NOP << 8 |
1302						   TCPOPT_NOP, ptr);
1303				ptr += 1;
1304			}
1305		}
1306	}
1307
1308	if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1309		u8 i = 1;
 
 
 
1310
1311		*ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1312				      TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr,
1313				      0, opts->rm_list.ids[0]);
 
 
 
 
 
1314
1315		while (i < opts->rm_list.nr) {
1316			u8 id1, id2, id3, id4;
 
 
 
1317
1318			id1 = opts->rm_list.ids[i];
1319			id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP;
1320			id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP;
1321			id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP;
1322			put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr);
1323			ptr += 1;
1324			i += 4;
1325		}
 
 
1326	}
1327
1328	if (OPTION_MPTCP_PRIO & opts->suboptions) {
1329		const struct sock *ssk = (const struct sock *)tp;
1330		struct mptcp_subflow_context *subflow;
1331
1332		subflow = mptcp_subflow_ctx(ssk);
1333		subflow->send_mp_prio = 0;
1334
1335		*ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
1336				      TCPOLEN_MPTCP_PRIO,
1337				      opts->backup, TCPOPT_NOP);
1338	}
1339
1340	if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1341		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1342				      TCPOLEN_MPTCP_MPJ_SYN,
1343				      opts->backup, opts->join_id);
1344		put_unaligned_be32(opts->token, ptr);
1345		ptr += 1;
1346		put_unaligned_be32(opts->nonce, ptr);
1347		ptr += 1;
1348	}
1349
1350	if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1351		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1352				      TCPOLEN_MPTCP_MPJ_SYNACK,
1353				      opts->backup, opts->join_id);
1354		put_unaligned_be64(opts->thmac, ptr);
1355		ptr += 2;
1356		put_unaligned_be32(opts->nonce, ptr);
1357		ptr += 1;
1358	}
1359
1360	if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1361		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1362				      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1363		memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1364		ptr += 5;
1365	}
1366
1367	if (OPTION_MPTCP_RST & opts->suboptions)
1368		*ptr++ = mptcp_option(MPTCPOPT_RST,
1369				      TCPOLEN_MPTCP_RST,
1370				      opts->reset_transient,
1371				      opts->reset_reason);
1372
1373	if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1374		struct mptcp_ext *mpext = &opts->ext_copy;
1375		u8 len = TCPOLEN_MPTCP_DSS_BASE;
1376		u8 flags = 0;
1377
1378		if (mpext->use_ack) {
1379			flags = MPTCP_DSS_HAS_ACK;
1380			if (mpext->ack64) {
1381				len += TCPOLEN_MPTCP_DSS_ACK64;
1382				flags |= MPTCP_DSS_ACK64;
1383			} else {
1384				len += TCPOLEN_MPTCP_DSS_ACK32;
1385			}
1386		}
1387
1388		if (mpext->use_map) {
1389			len += TCPOLEN_MPTCP_DSS_MAP64;
1390
1391			/* Use only 64-bit mapping flags for now, add
1392			 * support for optional 32-bit mappings later.
1393			 */
1394			flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1395			if (mpext->data_fin)
1396				flags |= MPTCP_DSS_DATA_FIN;
1397
1398			if (opts->csum_reqd)
1399				len += TCPOLEN_MPTCP_DSS_CHECKSUM;
1400		}
1401
1402		*ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
 
 
1403
1404		if (mpext->use_ack) {
1405			if (mpext->ack64) {
1406				put_unaligned_be64(mpext->data_ack, ptr);
1407				ptr += 2;
1408			} else {
1409				put_unaligned_be32(mpext->data_ack32, ptr);
1410				ptr += 1;
1411			}
1412		}
1413
1414		if (mpext->use_map) {
1415			put_unaligned_be64(mpext->data_seq, ptr);
1416			ptr += 2;
1417			put_unaligned_be32(mpext->subflow_seq, ptr);
 
1418			ptr += 1;
1419			if (opts->csum_reqd) {
1420				put_unaligned_be32(mpext->data_len << 16 |
1421						   mptcp_make_csum(mpext), ptr);
1422			} else {
1423				put_unaligned_be32(mpext->data_len << 16 |
1424						   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1425			}
1426		}
1427	}
1428
1429	if (tp)
1430		mptcp_set_rwin(tp);
1431}
1432
1433__be32 mptcp_get_reset_option(const struct sk_buff *skb)
1434{
1435	const struct mptcp_ext *ext = mptcp_get_ext(skb);
1436	u8 flags, reason;
1437
1438	if (ext) {
1439		flags = ext->reset_transient;
1440		reason = ext->reset_reason;
1441
1442		return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
1443				    flags, reason);
1444	}
1445
1446	return htonl(0u);
1447}
1448EXPORT_SYMBOL_GPL(mptcp_get_reset_option);