1 // SPDX-License-Identifier: GPL-2.0
4 * Copyright (c) 2017 - 2019, Intel Corporation.
7 #define pr_fmt(fmt) "MPTCP: " fmt
9 #include <linux/kernel.h>
10 #include <crypto/sha.h>
12 #include <net/mptcp.h>
16 static bool mptcp_cap_flag_sha256(u8 flags)
18 return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
21 static void mptcp_parse_option(const struct sk_buff *skb,
22 const unsigned char *ptr, int opsize,
23 struct mptcp_options_received *mp_opt)
25 u8 subtype = *ptr >> 4;
31 case MPTCPOPT_MP_CAPABLE:
32 /* strict size checking */
33 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
34 if (skb->len > tcp_hdr(skb)->doff << 2)
35 expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
37 expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
39 if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
40 expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
42 expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
44 if (opsize != expected_opsize)
47 /* try to be gentle vs future versions on the initial syn */
48 version = *ptr++ & MPTCP_VERSION_MASK;
49 if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
50 if (version != MPTCP_SUPPORTED_VERSION)
52 } else if (version < MPTCP_SUPPORTED_VERSION) {
57 if (!mptcp_cap_flag_sha256(flags) ||
58 (flags & MPTCP_CAP_EXTENSIBILITY))
61 /* RFC 6824, Section 3.1:
62 * "For the Checksum Required bit (labeled "A"), if either
63 * host requires the use of checksums, checksums MUST be used.
64 * In other words, the only way for checksums not to be used
65 * is if both hosts in their SYNs set A=0."
68 * "If a checksum is not present when its use has been
69 * negotiated, the receiver MUST close the subflow with a RST as
70 * it is considered broken."
72 * We don't implement DSS checksum - fall back to TCP.
74 if (flags & MPTCP_CAP_CHECKSUM_REQD)
77 mp_opt->mp_capable = 1;
78 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
79 mp_opt->sndr_key = get_unaligned_be64(ptr);
82 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
83 mp_opt->rcvr_key = get_unaligned_be64(ptr);
86 if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA) {
88 * "the data parameters in a MP_CAPABLE are semantically
89 * equivalent to those in a DSS option and can be used
96 mp_opt->data_len = get_unaligned_be16(ptr);
99 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
100 version, flags, opsize, mp_opt->sndr_key,
101 mp_opt->rcvr_key, mp_opt->data_len);
104 case MPTCPOPT_MP_JOIN:
106 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
107 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
108 mp_opt->join_id = *ptr++;
109 mp_opt->token = get_unaligned_be32(ptr);
111 mp_opt->nonce = get_unaligned_be32(ptr);
113 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
114 mp_opt->backup, mp_opt->join_id,
115 mp_opt->token, mp_opt->nonce);
116 } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
117 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
118 mp_opt->join_id = *ptr++;
119 mp_opt->thmac = get_unaligned_be64(ptr);
121 mp_opt->nonce = get_unaligned_be32(ptr);
123 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
124 mp_opt->backup, mp_opt->join_id,
125 mp_opt->thmac, mp_opt->nonce);
126 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
128 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
129 pr_debug("MP_JOIN hmac");
139 /* we must clear 'mpc_map' be able to detect MP_CAPABLE
140 * map vs DSS map in mptcp_incoming_options(), and reconstruct
141 * map info accordingly
144 flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
145 mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
146 mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
147 mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
148 mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
149 mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
151 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
152 mp_opt->data_fin, mp_opt->dsn64,
153 mp_opt->use_map, mp_opt->ack64,
156 expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
158 if (mp_opt->use_ack) {
160 expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
162 expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
165 if (mp_opt->use_map) {
167 expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
169 expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
172 /* RFC 6824, Section 3.3:
173 * If a checksum is present, but its use had
174 * not been negotiated in the MP_CAPABLE handshake,
175 * the checksum field MUST be ignored.
177 if (opsize != expected_opsize &&
178 opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
183 if (mp_opt->use_ack) {
185 mp_opt->data_ack = get_unaligned_be64(ptr);
188 mp_opt->data_ack = get_unaligned_be32(ptr);
192 pr_debug("data_ack=%llu", mp_opt->data_ack);
195 if (mp_opt->use_map) {
197 mp_opt->data_seq = get_unaligned_be64(ptr);
200 mp_opt->data_seq = get_unaligned_be32(ptr);
204 mp_opt->subflow_seq = get_unaligned_be32(ptr);
207 mp_opt->data_len = get_unaligned_be16(ptr);
210 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
211 mp_opt->data_seq, mp_opt->subflow_seq,
217 case MPTCPOPT_ADD_ADDR:
218 mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
220 if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
221 opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
222 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
223 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
224 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
225 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
226 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
231 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
232 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
233 mp_opt->family = MPTCP_ADDR_IPVERSION_4;
234 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
235 else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
236 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
237 mp_opt->family = MPTCP_ADDR_IPVERSION_6;
243 mp_opt->add_addr = 1;
244 mp_opt->addr_id = *ptr++;
245 pr_debug("ADD_ADDR: id=%d, echo=%d", mp_opt->addr_id, mp_opt->echo);
246 if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
247 memcpy((u8 *)&mp_opt->addr.s_addr, (u8 *)ptr, 4);
249 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
250 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
251 mp_opt->port = get_unaligned_be16(ptr);
255 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
257 memcpy(mp_opt->addr6.s6_addr, (u8 *)ptr, 16);
259 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
260 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
261 mp_opt->port = get_unaligned_be16(ptr);
267 mp_opt->ahmac = get_unaligned_be64(ptr);
272 case MPTCPOPT_RM_ADDR:
273 if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
279 mp_opt->rm_id = *ptr++;
280 pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
288 void mptcp_get_options(const struct sk_buff *skb,
289 struct mptcp_options_received *mp_opt)
291 const struct tcphdr *th = tcp_hdr(skb);
292 const unsigned char *ptr;
295 /* initialize option status */
296 mp_opt->mp_capable = 0;
298 mp_opt->add_addr = 0;
304 length = (th->doff * 4) - sizeof(struct tcphdr);
305 ptr = (const unsigned char *)(th + 1);
314 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
321 if (opsize < 2) /* "silly options" */
324 return; /* don't parse partial options */
325 if (opcode == TCPOPT_MPTCP)
326 mptcp_parse_option(skb, ptr, opsize, mp_opt);
333 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
334 unsigned int *size, struct mptcp_out_options *opts)
336 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
338 /* we will use snd_isn to detect first pkt [re]transmission
339 * in mptcp_established_options_mp()
341 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
342 if (subflow->request_mptcp) {
343 opts->suboptions = OPTION_MPTCP_MPC_SYN;
344 *size = TCPOLEN_MPTCP_MPC_SYN;
346 } else if (subflow->request_join) {
347 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
348 subflow->local_nonce);
349 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
350 opts->join_id = subflow->local_id;
351 opts->token = subflow->remote_token;
352 opts->nonce = subflow->local_nonce;
353 opts->backup = subflow->request_bkup;
354 *size = TCPOLEN_MPTCP_MPJ_SYN;
360 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
361 * TCP can't schedule delack timer before the subflow is fully established.
362 * MPTCP uses the delack timer to do 3rd ack retransmissions
364 static void schedule_3rdack_retransmission(struct sock *sk)
366 struct inet_connection_sock *icsk = inet_csk(sk);
367 struct tcp_sock *tp = tcp_sk(sk);
368 unsigned long timeout;
370 /* reschedule with a timeout above RTT, as we must look only for drop */
372 timeout = usecs_to_jiffies(tp->srtt_us >> (3 - 1));
374 timeout = TCP_TIMEOUT_INIT;
377 WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
378 icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
379 icsk->icsk_ack.timeout = timeout;
380 sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
383 static void clear_3rdack_retransmission(struct sock *sk)
385 struct inet_connection_sock *icsk = inet_csk(sk);
387 sk_stop_timer(sk, &icsk->icsk_delack_timer);
388 icsk->icsk_ack.timeout = 0;
389 icsk->icsk_ack.ato = 0;
390 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
393 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
395 unsigned int remaining,
396 struct mptcp_out_options *opts)
398 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
399 struct mptcp_ext *mpext;
400 unsigned int data_len;
402 /* When skb is not available, we better over-estimate the emitted
403 * options len. A full DSS option (28 bytes) is longer than
404 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
405 * tell the caller to defer the estimate to
406 * mptcp_established_options_dss(), which will reserve enough space.
411 /* MPC/MPJ needed only on 3rd ack packet */
412 if (subflow->fully_established ||
413 subflow->snd_isn != TCP_SKB_CB(skb)->seq)
416 if (subflow->mp_capable) {
417 mpext = mptcp_get_ext(skb);
418 data_len = mpext ? mpext->data_len : 0;
420 /* we will check ext_copy.data_len in mptcp_write_options() to
421 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
422 * TCPOLEN_MPTCP_MPC_ACK
424 opts->ext_copy.data_len = data_len;
425 opts->suboptions = OPTION_MPTCP_MPC_ACK;
426 opts->sndr_key = subflow->local_key;
427 opts->rcvr_key = subflow->remote_key;
430 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
431 * packets that start the first subflow of an MPTCP connection,
432 * as well as the first packet that carries data
435 *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
437 *size = TCPOLEN_MPTCP_MPC_ACK;
439 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
440 subflow, subflow->local_key, subflow->remote_key,
444 } else if (subflow->mp_join) {
445 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
446 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
447 *size = TCPOLEN_MPTCP_MPJ_ACK;
448 pr_debug("subflow=%p", subflow);
450 schedule_3rdack_retransmission(sk);
456 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
457 struct sk_buff *skb, struct mptcp_ext *ext)
459 /* The write_seq value has already been incremented, so the actual
460 * sequence number for the DATA_FIN is one less.
462 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
464 if (!ext->use_map || !skb->len) {
465 /* RFC6824 requires a DSS mapping with specific values
466 * if DATA_FIN is set but no data payload is mapped
471 ext->data_seq = data_fin_tx_seq;
472 ext->subflow_seq = 0;
474 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
475 /* If there's an existing DSS mapping and it is the
476 * final mapping, DATA_FIN consumes 1 additional byte of
484 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
486 unsigned int remaining,
487 struct mptcp_out_options *opts)
489 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
490 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
491 unsigned int dss_size = 0;
492 u64 snd_data_fin_enable;
493 struct mptcp_ext *mpext;
494 unsigned int ack_size;
497 mpext = skb ? mptcp_get_ext(skb) : NULL;
498 snd_data_fin_enable = READ_ONCE(msk->snd_data_fin_enable);
500 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
501 unsigned int map_size;
503 map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
505 remaining -= map_size;
508 opts->ext_copy = *mpext;
510 if (skb && snd_data_fin_enable)
511 mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
515 /* passive sockets msk will set the 'can_ack' after accept(), even
516 * if the first subflow may have the already the remote key handy
518 opts->ext_copy.use_ack = 0;
519 if (!READ_ONCE(msk->can_ack)) {
520 *size = ALIGN(dss_size, 4);
524 if (READ_ONCE(msk->use_64bit_ack)) {
525 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
526 opts->ext_copy.data_ack = READ_ONCE(msk->ack_seq);
527 opts->ext_copy.ack64 = 1;
529 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
530 opts->ext_copy.data_ack32 = (uint32_t)READ_ONCE(msk->ack_seq);
531 opts->ext_copy.ack64 = 0;
533 opts->ext_copy.use_ack = 1;
535 /* Add kind/length/subtype/flag overhead if mapping is not populated */
537 ack_size += TCPOLEN_MPTCP_DSS_BASE;
539 dss_size += ack_size;
541 *size = ALIGN(dss_size, 4);
545 static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
546 struct in_addr *addr)
548 u8 hmac[SHA256_DIGEST_SIZE];
552 memcpy(&msg[1], &addr->s_addr, 4);
556 mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
558 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
561 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
562 static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
563 struct in6_addr *addr)
565 u8 hmac[SHA256_DIGEST_SIZE];
569 memcpy(&msg[1], &addr->s6_addr, 16);
573 mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
575 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
579 static bool mptcp_established_options_add_addr(struct sock *sk,
581 unsigned int remaining,
582 struct mptcp_out_options *opts)
584 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
585 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
586 struct mptcp_addr_info saddr;
590 if (!mptcp_pm_should_add_signal(msk) ||
591 !(mptcp_pm_add_addr_signal(msk, remaining, &saddr, &echo)))
594 len = mptcp_add_addr_len(saddr.family, echo);
599 opts->addr_id = saddr.id;
600 if (saddr.family == AF_INET) {
601 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
602 opts->addr = saddr.addr;
604 opts->ahmac = add_addr_generate_hmac(msk->local_key,
610 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
611 else if (saddr.family == AF_INET6) {
612 opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
613 opts->addr6 = saddr.addr6;
615 opts->ahmac = add_addr6_generate_hmac(msk->local_key,
622 pr_debug("addr_id=%d, ahmac=%llu, echo=%d", opts->addr_id, opts->ahmac, echo);
627 static bool mptcp_established_options_rm_addr(struct sock *sk,
629 unsigned int remaining,
630 struct mptcp_out_options *opts)
632 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
633 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
636 if (!mptcp_pm_should_rm_signal(msk) ||
637 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_id)))
640 if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
643 *size = TCPOLEN_MPTCP_RM_ADDR_BASE;
644 opts->suboptions |= OPTION_MPTCP_RM_ADDR;
647 pr_debug("rm_id=%d", opts->rm_id);
652 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
653 unsigned int *size, unsigned int remaining,
654 struct mptcp_out_options *opts)
656 unsigned int opt_size = 0;
659 opts->suboptions = 0;
661 if (unlikely(mptcp_check_fallback(sk)))
664 /* prevent adding of any MPTCP related options on reset packet
665 * until we support MP_TCPRST/MP_FASTCLOSE
667 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
670 if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
672 else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
676 /* we reserved enough space for the above options, and exceeding the
677 * TCP option space would be fatal
679 if (WARN_ON_ONCE(opt_size > remaining))
683 remaining -= opt_size;
684 if (mptcp_established_options_add_addr(sk, &opt_size, remaining, opts)) {
686 remaining -= opt_size;
688 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
690 remaining -= opt_size;
697 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
698 struct mptcp_out_options *opts)
700 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
702 if (subflow_req->mp_capable) {
703 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
704 opts->sndr_key = subflow_req->local_key;
705 *size = TCPOLEN_MPTCP_MPC_SYNACK;
706 pr_debug("subflow_req=%p, local_key=%llu",
707 subflow_req, subflow_req->local_key);
709 } else if (subflow_req->mp_join) {
710 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
711 opts->backup = subflow_req->backup;
712 opts->join_id = subflow_req->local_id;
713 opts->thmac = subflow_req->thmac;
714 opts->nonce = subflow_req->local_nonce;
715 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
716 subflow_req, opts->backup, opts->join_id,
717 opts->thmac, opts->nonce);
718 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
724 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
725 struct mptcp_subflow_context *subflow,
727 struct mptcp_options_received *mp_opt)
729 /* here we can process OoO, in-window pkts, only in-sequence 4th ack
730 * will make the subflow fully established
732 if (likely(subflow->fully_established)) {
733 /* on passive sockets, check for 3rd ack retransmission
734 * note that msk is always set by subflow_syn_recv_sock()
735 * for mp_join subflows
737 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
738 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
739 subflow->mp_join && mp_opt->mp_join &&
740 READ_ONCE(msk->pm.server_side))
742 goto fully_established;
745 /* we must process OoO packets before the first subflow is fully
746 * established. OoO packets are instead a protocol violation
747 * for MP_JOIN subflows as the peer must not send any data
748 * before receiving the forth ack - cfr. RFC 8684 section 3.2.
750 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
751 if (subflow->mp_join)
753 return subflow->mp_capable;
756 if (mp_opt->dss && mp_opt->use_ack) {
757 /* subflows are fully established as soon as we get any
760 subflow->fully_established = 1;
761 WRITE_ONCE(msk->fully_established, true);
762 goto fully_established;
765 /* If the first established packet does not contain MP_CAPABLE + data
766 * then fallback to TCP. Fallback scenarios requires a reset for
769 if (!mp_opt->mp_capable) {
770 if (subflow->mp_join)
772 subflow->mp_capable = 0;
774 __mptcp_do_fallback(msk);
778 if (unlikely(!READ_ONCE(msk->pm.server_side)))
779 pr_warn_once("bogus mpc option on established client sk");
780 mptcp_subflow_fully_established(subflow, mp_opt);
783 if (likely(subflow->pm_notified))
786 subflow->pm_notified = 1;
787 if (subflow->mp_join) {
788 clear_3rdack_retransmission(ssk);
789 mptcp_pm_subflow_established(msk, subflow);
791 mptcp_pm_fully_established(msk);
796 mptcp_subflow_reset(ssk);
800 static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
802 u32 old_ack32, cur_ack32;
807 old_ack32 = (u32)old_ack;
808 cur_ack32 = (u32)cur_ack;
809 cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
810 if (unlikely(before(cur_ack32, old_ack32)))
811 return cur_ack + (1LL << 32);
815 static void update_una(struct mptcp_sock *msk,
816 struct mptcp_options_received *mp_opt)
818 u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
819 u64 write_seq = READ_ONCE(msk->write_seq);
821 /* avoid ack expansion on update conflict, to reduce the risk of
822 * wrongly expanding to a future ack sequence number, which is way
823 * more dangerous than missing an ack
825 new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
827 /* ACK for data not even sent yet? Ignore. */
828 if (after64(new_snd_una, write_seq))
829 new_snd_una = old_snd_una;
831 while (after64(new_snd_una, old_snd_una)) {
832 snd_una = old_snd_una;
833 old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
835 if (old_snd_una == snd_una) {
836 mptcp_data_acked((struct sock *)msk);
842 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
844 /* Skip if DATA_FIN was already received.
845 * If updating simultaneously with the recvmsg loop, values
846 * should match. If they mismatch, the peer is misbehaving and
847 * we will prefer the most recent information.
849 if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
852 WRITE_ONCE(msk->rcv_data_fin_seq,
853 expand_ack(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
854 WRITE_ONCE(msk->rcv_data_fin, 1);
859 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
860 struct mptcp_options_received *mp_opt)
867 if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
868 hmac = add_addr_generate_hmac(msk->remote_key,
870 mp_opt->addr_id, &mp_opt->addr);
871 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
873 hmac = add_addr6_generate_hmac(msk->remote_key,
875 mp_opt->addr_id, &mp_opt->addr6);
878 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
879 msk, (unsigned long long)hmac,
880 (unsigned long long)mp_opt->ahmac);
882 return hmac == mp_opt->ahmac;
885 void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
887 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
888 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
889 struct mptcp_options_received mp_opt;
890 struct mptcp_ext *mpext;
892 if (__mptcp_check_fallback(msk))
895 mptcp_get_options(skb, &mp_opt);
896 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
899 if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
900 struct mptcp_addr_info addr;
902 addr.port = htons(mp_opt.port);
903 addr.id = mp_opt.addr_id;
904 if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
905 addr.family = AF_INET;
906 addr.addr = mp_opt.addr;
908 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
909 else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
910 addr.family = AF_INET6;
911 addr.addr6 = mp_opt.addr6;
915 mptcp_pm_add_addr_received(msk, &addr);
916 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
918 mptcp_pm_del_add_timer(msk, &addr);
919 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
924 if (mp_opt.rm_addr) {
925 mptcp_pm_rm_addr_received(msk, mp_opt.rm_id);
932 /* we can't wait for recvmsg() to update the ack_seq, otherwise
933 * monodirectional flows will stuck
936 update_una(msk, &mp_opt);
938 /* Zero-data-length packets are dropped by the caller and not
939 * propagated to the MPTCP layer, so the skb extension does not
940 * need to be allocated or populated. DATA_FIN information, if
941 * present, needs to be updated here before the skb is freed.
943 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
944 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
945 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64) &&
946 schedule_work(&msk->work))
947 sock_hold(subflow->conn);
952 mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
956 memset(mpext, 0, sizeof(*mpext));
958 if (mp_opt.use_map) {
959 if (mp_opt.mpc_map) {
960 /* this is an MP_CAPABLE carrying MPTCP data
961 * we know this map the first chunk of data
963 mptcp_crypto_key_sha(subflow->remote_key, NULL,
966 mpext->subflow_seq = 1;
971 mpext->data_seq = mp_opt.data_seq;
972 mpext->subflow_seq = mp_opt.subflow_seq;
973 mpext->dsn64 = mp_opt.dsn64;
974 mpext->data_fin = mp_opt.data_fin;
976 mpext->data_len = mp_opt.data_len;
981 void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
983 if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
984 OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
987 if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
988 len = TCPOLEN_MPTCP_MPC_SYN;
989 else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
990 len = TCPOLEN_MPTCP_MPC_SYNACK;
991 else if (opts->ext_copy.data_len)
992 len = TCPOLEN_MPTCP_MPC_ACK_DATA;
994 len = TCPOLEN_MPTCP_MPC_ACK;
996 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
997 MPTCP_SUPPORTED_VERSION,
998 MPTCP_CAP_HMAC_SHA256);
1000 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1002 goto mp_capable_done;
1004 put_unaligned_be64(opts->sndr_key, ptr);
1006 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1007 goto mp_capable_done;
1009 put_unaligned_be64(opts->rcvr_key, ptr);
1011 if (!opts->ext_copy.data_len)
1012 goto mp_capable_done;
1014 put_unaligned_be32(opts->ext_copy.data_len << 16 |
1015 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1020 if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1022 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1023 TCPOLEN_MPTCP_ADD_ADDR, 0,
1026 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1027 TCPOLEN_MPTCP_ADD_ADDR_BASE,
1030 memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
1033 put_unaligned_be64(opts->ahmac, ptr);
1038 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1039 if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
1041 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1042 TCPOLEN_MPTCP_ADD_ADDR6, 0,
1045 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1046 TCPOLEN_MPTCP_ADD_ADDR6_BASE,
1049 memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
1052 put_unaligned_be64(opts->ahmac, ptr);
1058 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1059 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1060 TCPOLEN_MPTCP_RM_ADDR_BASE,
1064 if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1065 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1066 TCPOLEN_MPTCP_MPJ_SYN,
1067 opts->backup, opts->join_id);
1068 put_unaligned_be32(opts->token, ptr);
1070 put_unaligned_be32(opts->nonce, ptr);
1074 if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1075 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1076 TCPOLEN_MPTCP_MPJ_SYNACK,
1077 opts->backup, opts->join_id);
1078 put_unaligned_be64(opts->thmac, ptr);
1080 put_unaligned_be32(opts->nonce, ptr);
1084 if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1085 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1086 TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1087 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1091 if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
1092 struct mptcp_ext *mpext = &opts->ext_copy;
1093 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1096 if (mpext->use_ack) {
1097 flags = MPTCP_DSS_HAS_ACK;
1099 len += TCPOLEN_MPTCP_DSS_ACK64;
1100 flags |= MPTCP_DSS_ACK64;
1102 len += TCPOLEN_MPTCP_DSS_ACK32;
1106 if (mpext->use_map) {
1107 len += TCPOLEN_MPTCP_DSS_MAP64;
1109 /* Use only 64-bit mapping flags for now, add
1110 * support for optional 32-bit mappings later.
1112 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1113 if (mpext->data_fin)
1114 flags |= MPTCP_DSS_DATA_FIN;
1117 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1119 if (mpext->use_ack) {
1121 put_unaligned_be64(mpext->data_ack, ptr);
1124 put_unaligned_be32(mpext->data_ack32, ptr);
1129 if (mpext->use_map) {
1130 put_unaligned_be64(mpext->data_seq, ptr);
1132 put_unaligned_be32(mpext->subflow_seq, ptr);
1134 put_unaligned_be32(mpext->data_len << 16 |
1135 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);