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>
15 static bool mptcp_cap_flag_sha256(u8 flags
)
17 return (flags
& MPTCP_CAP_FLAG_MASK
) == MPTCP_CAP_HMAC_SHA256
;
20 static void mptcp_parse_option(const struct sk_buff
*skb
,
21 const unsigned char *ptr
, int opsize
,
22 struct mptcp_options_received
*mp_opt
)
24 u8 subtype
= *ptr
>> 4;
30 case MPTCPOPT_MP_CAPABLE
:
31 /* strict size checking */
32 if (!(TCP_SKB_CB(skb
)->tcp_flags
& TCPHDR_SYN
)) {
33 if (skb
->len
> tcp_hdr(skb
)->doff
<< 2)
34 expected_opsize
= TCPOLEN_MPTCP_MPC_ACK_DATA
;
36 expected_opsize
= TCPOLEN_MPTCP_MPC_ACK
;
38 if (TCP_SKB_CB(skb
)->tcp_flags
& TCPHDR_ACK
)
39 expected_opsize
= TCPOLEN_MPTCP_MPC_SYNACK
;
41 expected_opsize
= TCPOLEN_MPTCP_MPC_SYN
;
43 if (opsize
!= expected_opsize
)
46 /* try to be gentle vs future versions on the initial syn */
47 version
= *ptr
++ & MPTCP_VERSION_MASK
;
48 if (opsize
!= TCPOLEN_MPTCP_MPC_SYN
) {
49 if (version
!= MPTCP_SUPPORTED_VERSION
)
51 } else if (version
< MPTCP_SUPPORTED_VERSION
) {
56 if (!mptcp_cap_flag_sha256(flags
) ||
57 (flags
& MPTCP_CAP_EXTENSIBILITY
))
60 /* RFC 6824, Section 3.1:
61 * "For the Checksum Required bit (labeled "A"), if either
62 * host requires the use of checksums, checksums MUST be used.
63 * In other words, the only way for checksums not to be used
64 * is if both hosts in their SYNs set A=0."
67 * "If a checksum is not present when its use has been
68 * negotiated, the receiver MUST close the subflow with a RST as
69 * it is considered broken."
71 * We don't implement DSS checksum - fall back to TCP.
73 if (flags
& MPTCP_CAP_CHECKSUM_REQD
)
76 mp_opt
->mp_capable
= 1;
77 if (opsize
>= TCPOLEN_MPTCP_MPC_SYNACK
) {
78 mp_opt
->sndr_key
= get_unaligned_be64(ptr
);
81 if (opsize
>= TCPOLEN_MPTCP_MPC_ACK
) {
82 mp_opt
->rcvr_key
= get_unaligned_be64(ptr
);
85 if (opsize
== TCPOLEN_MPTCP_MPC_ACK_DATA
) {
87 * "the data parameters in a MP_CAPABLE are semantically
88 * equivalent to those in a DSS option and can be used
94 mp_opt
->data_len
= get_unaligned_be16(ptr
);
97 pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
98 version
, flags
, opsize
, mp_opt
->sndr_key
,
99 mp_opt
->rcvr_key
, mp_opt
->data_len
);
102 case MPTCPOPT_MP_JOIN
:
104 if (opsize
== TCPOLEN_MPTCP_MPJ_SYN
) {
105 mp_opt
->backup
= *ptr
++ & MPTCPOPT_BACKUP
;
106 mp_opt
->join_id
= *ptr
++;
107 mp_opt
->token
= get_unaligned_be32(ptr
);
109 mp_opt
->nonce
= get_unaligned_be32(ptr
);
111 pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
112 mp_opt
->backup
, mp_opt
->join_id
,
113 mp_opt
->token
, mp_opt
->nonce
);
114 } else if (opsize
== TCPOLEN_MPTCP_MPJ_SYNACK
) {
115 mp_opt
->backup
= *ptr
++ & MPTCPOPT_BACKUP
;
116 mp_opt
->join_id
= *ptr
++;
117 mp_opt
->thmac
= get_unaligned_be64(ptr
);
119 mp_opt
->nonce
= get_unaligned_be32(ptr
);
121 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
122 mp_opt
->backup
, mp_opt
->join_id
,
123 mp_opt
->thmac
, mp_opt
->nonce
);
124 } else if (opsize
== TCPOLEN_MPTCP_MPJ_ACK
) {
126 memcpy(mp_opt
->hmac
, ptr
, MPTCPOPT_HMAC_LEN
);
127 pr_debug("MP_JOIN hmac");
129 pr_warn("MP_JOIN bad option size");
138 /* we must clear 'mpc_map' be able to detect MP_CAPABLE
139 * map vs DSS map in mptcp_incoming_options(), and reconstruct
140 * map info accordingly
143 flags
= (*ptr
++) & MPTCP_DSS_FLAG_MASK
;
144 mp_opt
->data_fin
= (flags
& MPTCP_DSS_DATA_FIN
) != 0;
145 mp_opt
->dsn64
= (flags
& MPTCP_DSS_DSN64
) != 0;
146 mp_opt
->use_map
= (flags
& MPTCP_DSS_HAS_MAP
) != 0;
147 mp_opt
->ack64
= (flags
& MPTCP_DSS_ACK64
) != 0;
148 mp_opt
->use_ack
= (flags
& MPTCP_DSS_HAS_ACK
);
150 pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
151 mp_opt
->data_fin
, mp_opt
->dsn64
,
152 mp_opt
->use_map
, mp_opt
->ack64
,
155 expected_opsize
= TCPOLEN_MPTCP_DSS_BASE
;
157 if (mp_opt
->use_ack
) {
159 expected_opsize
+= TCPOLEN_MPTCP_DSS_ACK64
;
161 expected_opsize
+= TCPOLEN_MPTCP_DSS_ACK32
;
164 if (mp_opt
->use_map
) {
166 expected_opsize
+= TCPOLEN_MPTCP_DSS_MAP64
;
168 expected_opsize
+= TCPOLEN_MPTCP_DSS_MAP32
;
171 /* RFC 6824, Section 3.3:
172 * If a checksum is present, but its use had
173 * not been negotiated in the MP_CAPABLE handshake,
174 * the checksum field MUST be ignored.
176 if (opsize
!= expected_opsize
&&
177 opsize
!= expected_opsize
+ TCPOLEN_MPTCP_DSS_CHECKSUM
)
182 if (mp_opt
->use_ack
) {
184 mp_opt
->data_ack
= get_unaligned_be64(ptr
);
187 mp_opt
->data_ack
= get_unaligned_be32(ptr
);
191 pr_debug("data_ack=%llu", mp_opt
->data_ack
);
194 if (mp_opt
->use_map
) {
196 mp_opt
->data_seq
= get_unaligned_be64(ptr
);
199 mp_opt
->data_seq
= get_unaligned_be32(ptr
);
203 mp_opt
->subflow_seq
= get_unaligned_be32(ptr
);
206 mp_opt
->data_len
= get_unaligned_be16(ptr
);
209 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
210 mp_opt
->data_seq
, mp_opt
->subflow_seq
,
216 case MPTCPOPT_ADD_ADDR
:
217 mp_opt
->echo
= (*ptr
++) & MPTCP_ADDR_ECHO
;
219 if (opsize
== TCPOLEN_MPTCP_ADD_ADDR
||
220 opsize
== TCPOLEN_MPTCP_ADD_ADDR_PORT
)
221 mp_opt
->family
= MPTCP_ADDR_IPVERSION_4
;
222 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
223 else if (opsize
== TCPOLEN_MPTCP_ADD_ADDR6
||
224 opsize
== TCPOLEN_MPTCP_ADD_ADDR6_PORT
)
225 mp_opt
->family
= MPTCP_ADDR_IPVERSION_6
;
230 if (opsize
== TCPOLEN_MPTCP_ADD_ADDR_BASE
||
231 opsize
== TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT
)
232 mp_opt
->family
= MPTCP_ADDR_IPVERSION_4
;
233 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
234 else if (opsize
== TCPOLEN_MPTCP_ADD_ADDR6_BASE
||
235 opsize
== TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT
)
236 mp_opt
->family
= MPTCP_ADDR_IPVERSION_6
;
242 mp_opt
->add_addr
= 1;
244 mp_opt
->addr_id
= *ptr
++;
245 pr_debug("ADD_ADDR: id=%d", mp_opt
->addr_id
);
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;
302 length
= (th
->doff
* 4) - sizeof(struct tcphdr
);
303 ptr
= (const unsigned char *)(th
+ 1);
312 case TCPOPT_NOP
: /* Ref: RFC 793 section 3.1 */
317 if (opsize
< 2) /* "silly options" */
320 return; /* don't parse partial options */
321 if (opcode
== TCPOPT_MPTCP
)
322 mptcp_parse_option(skb
, ptr
, opsize
, mp_opt
);
329 bool mptcp_syn_options(struct sock
*sk
, const struct sk_buff
*skb
,
330 unsigned int *size
, struct mptcp_out_options
*opts
)
332 struct mptcp_subflow_context
*subflow
= mptcp_subflow_ctx(sk
);
334 /* we will use snd_isn to detect first pkt [re]transmission
335 * in mptcp_established_options_mp()
337 subflow
->snd_isn
= TCP_SKB_CB(skb
)->end_seq
;
338 if (subflow
->request_mptcp
) {
339 opts
->suboptions
= OPTION_MPTCP_MPC_SYN
;
340 *size
= TCPOLEN_MPTCP_MPC_SYN
;
342 } else if (subflow
->request_join
) {
343 pr_debug("remote_token=%u, nonce=%u", subflow
->remote_token
,
344 subflow
->local_nonce
);
345 opts
->suboptions
= OPTION_MPTCP_MPJ_SYN
;
346 opts
->join_id
= subflow
->local_id
;
347 opts
->token
= subflow
->remote_token
;
348 opts
->nonce
= subflow
->local_nonce
;
349 opts
->backup
= subflow
->request_bkup
;
350 *size
= TCPOLEN_MPTCP_MPJ_SYN
;
356 /* MP_JOIN client subflow must wait for 4th ack before sending any data:
357 * TCP can't schedule delack timer before the subflow is fully established.
358 * MPTCP uses the delack timer to do 3rd ack retransmissions
360 static void schedule_3rdack_retransmission(struct sock
*sk
)
362 struct inet_connection_sock
*icsk
= inet_csk(sk
);
363 struct tcp_sock
*tp
= tcp_sk(sk
);
364 unsigned long timeout
;
366 /* reschedule with a timeout above RTT, as we must look only for drop */
368 timeout
= tp
->srtt_us
<< 1;
370 timeout
= TCP_TIMEOUT_INIT
;
372 WARN_ON_ONCE(icsk
->icsk_ack
.pending
& ICSK_ACK_TIMER
);
373 icsk
->icsk_ack
.pending
|= ICSK_ACK_SCHED
| ICSK_ACK_TIMER
;
374 icsk
->icsk_ack
.timeout
= timeout
;
375 sk_reset_timer(sk
, &icsk
->icsk_delack_timer
, timeout
);
378 static void clear_3rdack_retransmission(struct sock
*sk
)
380 struct inet_connection_sock
*icsk
= inet_csk(sk
);
382 sk_stop_timer(sk
, &icsk
->icsk_delack_timer
);
383 icsk
->icsk_ack
.timeout
= 0;
384 icsk
->icsk_ack
.ato
= 0;
385 icsk
->icsk_ack
.pending
&= ~(ICSK_ACK_SCHED
| ICSK_ACK_TIMER
);
388 static bool mptcp_established_options_mp(struct sock
*sk
, struct sk_buff
*skb
,
390 unsigned int remaining
,
391 struct mptcp_out_options
*opts
)
393 struct mptcp_subflow_context
*subflow
= mptcp_subflow_ctx(sk
);
394 struct mptcp_ext
*mpext
;
395 unsigned int data_len
;
397 /* When skb is not available, we better over-estimate the emitted
398 * options len. A full DSS option (28 bytes) is longer than
399 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
400 * tell the caller to defer the estimate to
401 * mptcp_established_options_dss(), which will reserve enough space.
406 /* MPC/MPJ needed only on 3rd ack packet */
407 if (subflow
->fully_established
||
408 subflow
->snd_isn
!= TCP_SKB_CB(skb
)->seq
)
411 if (subflow
->mp_capable
) {
412 mpext
= mptcp_get_ext(skb
);
413 data_len
= mpext
? mpext
->data_len
: 0;
415 /* we will check ext_copy.data_len in mptcp_write_options() to
416 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
417 * TCPOLEN_MPTCP_MPC_ACK
419 opts
->ext_copy
.data_len
= data_len
;
420 opts
->suboptions
= OPTION_MPTCP_MPC_ACK
;
421 opts
->sndr_key
= subflow
->local_key
;
422 opts
->rcvr_key
= subflow
->remote_key
;
425 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
426 * packets that start the first subflow of an MPTCP connection,
427 * as well as the first packet that carries data
430 *size
= ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA
, 4);
432 *size
= TCPOLEN_MPTCP_MPC_ACK
;
434 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
435 subflow
, subflow
->local_key
, subflow
->remote_key
,
439 } else if (subflow
->mp_join
) {
440 opts
->suboptions
= OPTION_MPTCP_MPJ_ACK
;
441 memcpy(opts
->hmac
, subflow
->hmac
, MPTCPOPT_HMAC_LEN
);
442 *size
= TCPOLEN_MPTCP_MPJ_ACK
;
443 pr_debug("subflow=%p", subflow
);
445 schedule_3rdack_retransmission(sk
);
451 static void mptcp_write_data_fin(struct mptcp_subflow_context
*subflow
,
452 struct sk_buff
*skb
, struct mptcp_ext
*ext
)
454 u64 data_fin_tx_seq
= READ_ONCE(mptcp_sk(subflow
->conn
)->write_seq
);
456 if (!ext
->use_map
|| !skb
->len
) {
457 /* RFC6824 requires a DSS mapping with specific values
458 * if DATA_FIN is set but no data payload is mapped
463 /* The write_seq value has already been incremented, so
464 * the actual sequence number for the DATA_FIN is one less.
466 ext
->data_seq
= data_fin_tx_seq
- 1;
467 ext
->subflow_seq
= 0;
469 } else if (ext
->data_seq
+ ext
->data_len
== data_fin_tx_seq
) {
470 /* If there's an existing DSS mapping and it is the
471 * final mapping, DATA_FIN consumes 1 additional byte of
479 static bool mptcp_established_options_dss(struct sock
*sk
, struct sk_buff
*skb
,
481 unsigned int remaining
,
482 struct mptcp_out_options
*opts
)
484 struct mptcp_subflow_context
*subflow
= mptcp_subflow_ctx(sk
);
485 struct mptcp_sock
*msk
= mptcp_sk(subflow
->conn
);
486 unsigned int dss_size
= 0;
487 u64 snd_data_fin_enable
;
488 struct mptcp_ext
*mpext
;
489 unsigned int ack_size
;
492 mpext
= skb
? mptcp_get_ext(skb
) : NULL
;
493 snd_data_fin_enable
= READ_ONCE(msk
->snd_data_fin_enable
);
495 if (!skb
|| (mpext
&& mpext
->use_map
) || snd_data_fin_enable
) {
496 unsigned int map_size
;
498 map_size
= TCPOLEN_MPTCP_DSS_BASE
+ TCPOLEN_MPTCP_DSS_MAP64
;
500 remaining
-= map_size
;
503 opts
->ext_copy
= *mpext
;
505 if (skb
&& snd_data_fin_enable
)
506 mptcp_write_data_fin(subflow
, skb
, &opts
->ext_copy
);
510 /* passive sockets msk will set the 'can_ack' after accept(), even
511 * if the first subflow may have the already the remote key handy
513 opts
->ext_copy
.use_ack
= 0;
514 if (!READ_ONCE(msk
->can_ack
)) {
515 *size
= ALIGN(dss_size
, 4);
519 if (subflow
->use_64bit_ack
) {
520 ack_size
= TCPOLEN_MPTCP_DSS_ACK64
;
521 opts
->ext_copy
.data_ack
= msk
->ack_seq
;
522 opts
->ext_copy
.ack64
= 1;
524 ack_size
= TCPOLEN_MPTCP_DSS_ACK32
;
525 opts
->ext_copy
.data_ack32
= (uint32_t)(msk
->ack_seq
);
526 opts
->ext_copy
.ack64
= 0;
528 opts
->ext_copy
.use_ack
= 1;
530 /* Add kind/length/subtype/flag overhead if mapping is not populated */
532 ack_size
+= TCPOLEN_MPTCP_DSS_BASE
;
534 dss_size
+= ack_size
;
536 *size
= ALIGN(dss_size
, 4);
540 static u64
add_addr_generate_hmac(u64 key1
, u64 key2
, u8 addr_id
,
541 struct in_addr
*addr
)
543 u8 hmac
[SHA256_DIGEST_SIZE
];
547 memcpy(&msg
[1], &addr
->s_addr
, 4);
551 mptcp_crypto_hmac_sha(key1
, key2
, msg
, 7, hmac
);
553 return get_unaligned_be64(&hmac
[SHA256_DIGEST_SIZE
- sizeof(u64
)]);
556 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
557 static u64
add_addr6_generate_hmac(u64 key1
, u64 key2
, u8 addr_id
,
558 struct in6_addr
*addr
)
560 u8 hmac
[SHA256_DIGEST_SIZE
];
564 memcpy(&msg
[1], &addr
->s6_addr
, 16);
568 mptcp_crypto_hmac_sha(key1
, key2
, msg
, 19, hmac
);
570 return get_unaligned_be64(&hmac
[SHA256_DIGEST_SIZE
- sizeof(u64
)]);
574 static bool mptcp_established_options_addr(struct sock
*sk
,
576 unsigned int remaining
,
577 struct mptcp_out_options
*opts
)
579 struct mptcp_subflow_context
*subflow
= mptcp_subflow_ctx(sk
);
580 struct mptcp_sock
*msk
= mptcp_sk(subflow
->conn
);
581 struct mptcp_addr_info saddr
;
584 if (!mptcp_pm_should_signal(msk
) ||
585 !(mptcp_pm_addr_signal(msk
, remaining
, &saddr
)))
588 len
= mptcp_add_addr_len(saddr
.family
);
593 opts
->addr_id
= saddr
.id
;
594 if (saddr
.family
== AF_INET
) {
595 opts
->suboptions
|= OPTION_MPTCP_ADD_ADDR
;
596 opts
->addr
= saddr
.addr
;
597 opts
->ahmac
= add_addr_generate_hmac(msk
->local_key
,
602 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
603 else if (saddr
.family
== AF_INET6
) {
604 opts
->suboptions
|= OPTION_MPTCP_ADD_ADDR6
;
605 opts
->addr6
= saddr
.addr6
;
606 opts
->ahmac
= add_addr6_generate_hmac(msk
->local_key
,
612 pr_debug("addr_id=%d, ahmac=%llu", opts
->addr_id
, opts
->ahmac
);
617 bool mptcp_established_options(struct sock
*sk
, struct sk_buff
*skb
,
618 unsigned int *size
, unsigned int remaining
,
619 struct mptcp_out_options
*opts
)
621 unsigned int opt_size
= 0;
624 opts
->suboptions
= 0;
626 if (unlikely(mptcp_check_fallback(sk
)))
629 if (mptcp_established_options_mp(sk
, skb
, &opt_size
, remaining
, opts
))
631 else if (mptcp_established_options_dss(sk
, skb
, &opt_size
, remaining
,
635 /* we reserved enough space for the above options, and exceeding the
636 * TCP option space would be fatal
638 if (WARN_ON_ONCE(opt_size
> remaining
))
642 remaining
-= opt_size
;
643 if (mptcp_established_options_addr(sk
, &opt_size
, remaining
, opts
)) {
645 remaining
-= opt_size
;
652 bool mptcp_synack_options(const struct request_sock
*req
, unsigned int *size
,
653 struct mptcp_out_options
*opts
)
655 struct mptcp_subflow_request_sock
*subflow_req
= mptcp_subflow_rsk(req
);
657 if (subflow_req
->mp_capable
) {
658 opts
->suboptions
= OPTION_MPTCP_MPC_SYNACK
;
659 opts
->sndr_key
= subflow_req
->local_key
;
660 *size
= TCPOLEN_MPTCP_MPC_SYNACK
;
661 pr_debug("subflow_req=%p, local_key=%llu",
662 subflow_req
, subflow_req
->local_key
);
664 } else if (subflow_req
->mp_join
) {
665 opts
->suboptions
= OPTION_MPTCP_MPJ_SYNACK
;
666 opts
->backup
= subflow_req
->backup
;
667 opts
->join_id
= subflow_req
->local_id
;
668 opts
->thmac
= subflow_req
->thmac
;
669 opts
->nonce
= subflow_req
->local_nonce
;
670 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
671 subflow_req
, opts
->backup
, opts
->join_id
,
672 opts
->thmac
, opts
->nonce
);
673 *size
= TCPOLEN_MPTCP_MPJ_SYNACK
;
679 static bool check_fully_established(struct mptcp_sock
*msk
, struct sock
*sk
,
680 struct mptcp_subflow_context
*subflow
,
682 struct mptcp_options_received
*mp_opt
)
684 /* here we can process OoO, in-window pkts, only in-sequence 4th ack
685 * will make the subflow fully established
687 if (likely(subflow
->fully_established
)) {
688 /* on passive sockets, check for 3rd ack retransmission
689 * note that msk is always set by subflow_syn_recv_sock()
690 * for mp_join subflows
692 if (TCP_SKB_CB(skb
)->seq
== subflow
->ssn_offset
+ 1 &&
693 TCP_SKB_CB(skb
)->end_seq
== TCP_SKB_CB(skb
)->seq
&&
694 subflow
->mp_join
&& mp_opt
->mp_join
&&
695 READ_ONCE(msk
->pm
.server_side
))
697 goto fully_established
;
700 /* we should process OoO packets before the first subflow is fully
701 * established, but not expected for MP_JOIN subflows
703 if (TCP_SKB_CB(skb
)->seq
!= subflow
->ssn_offset
+ 1)
704 return subflow
->mp_capable
;
706 if (mp_opt
->dss
&& mp_opt
->use_ack
) {
707 /* subflows are fully established as soon as we get any
710 subflow
->fully_established
= 1;
711 WRITE_ONCE(msk
->fully_established
, true);
712 goto fully_established
;
715 /* If the first established packet does not contain MP_CAPABLE + data
716 * then fallback to TCP
718 if (!mp_opt
->mp_capable
) {
719 subflow
->mp_capable
= 0;
721 __mptcp_do_fallback(msk
);
725 if (unlikely(!READ_ONCE(msk
->pm
.server_side
)))
726 pr_warn_once("bogus mpc option on established client sk");
727 mptcp_subflow_fully_established(subflow
, mp_opt
);
730 if (likely(subflow
->pm_notified
))
733 subflow
->pm_notified
= 1;
734 if (subflow
->mp_join
) {
735 clear_3rdack_retransmission(sk
);
736 mptcp_pm_subflow_established(msk
, subflow
);
738 mptcp_pm_fully_established(msk
);
743 static u64
expand_ack(u64 old_ack
, u64 cur_ack
, bool use_64bit
)
745 u32 old_ack32
, cur_ack32
;
750 old_ack32
= (u32
)old_ack
;
751 cur_ack32
= (u32
)cur_ack
;
752 cur_ack
= (old_ack
& GENMASK_ULL(63, 32)) + cur_ack32
;
753 if (unlikely(before(cur_ack32
, old_ack32
)))
754 return cur_ack
+ (1LL << 32);
758 static void update_una(struct mptcp_sock
*msk
,
759 struct mptcp_options_received
*mp_opt
)
761 u64 new_snd_una
, snd_una
, old_snd_una
= atomic64_read(&msk
->snd_una
);
762 u64 write_seq
= READ_ONCE(msk
->write_seq
);
764 /* avoid ack expansion on update conflict, to reduce the risk of
765 * wrongly expanding to a future ack sequence number, which is way
766 * more dangerous than missing an ack
768 new_snd_una
= expand_ack(old_snd_una
, mp_opt
->data_ack
, mp_opt
->ack64
);
770 /* ACK for data not even sent yet? Ignore. */
771 if (after64(new_snd_una
, write_seq
))
772 new_snd_una
= old_snd_una
;
774 while (after64(new_snd_una
, old_snd_una
)) {
775 snd_una
= old_snd_una
;
776 old_snd_una
= atomic64_cmpxchg(&msk
->snd_una
, snd_una
,
778 if (old_snd_una
== snd_una
) {
779 mptcp_data_acked((struct sock
*)msk
);
785 bool mptcp_update_rcv_data_fin(struct mptcp_sock
*msk
, u64 data_fin_seq
)
787 /* Skip if DATA_FIN was already received.
788 * If updating simultaneously with the recvmsg loop, values
789 * should match. If they mismatch, the peer is misbehaving and
790 * we will prefer the most recent information.
792 if (READ_ONCE(msk
->rcv_data_fin
) || !READ_ONCE(msk
->first
))
795 WRITE_ONCE(msk
->rcv_data_fin_seq
, data_fin_seq
);
796 WRITE_ONCE(msk
->rcv_data_fin
, 1);
801 static bool add_addr_hmac_valid(struct mptcp_sock
*msk
,
802 struct mptcp_options_received
*mp_opt
)
809 if (mp_opt
->family
== MPTCP_ADDR_IPVERSION_4
)
810 hmac
= add_addr_generate_hmac(msk
->remote_key
,
812 mp_opt
->addr_id
, &mp_opt
->addr
);
813 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
815 hmac
= add_addr6_generate_hmac(msk
->remote_key
,
817 mp_opt
->addr_id
, &mp_opt
->addr6
);
820 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
821 msk
, (unsigned long long)hmac
,
822 (unsigned long long)mp_opt
->ahmac
);
824 return hmac
== mp_opt
->ahmac
;
827 void mptcp_incoming_options(struct sock
*sk
, struct sk_buff
*skb
,
828 struct tcp_options_received
*opt_rx
)
830 struct mptcp_subflow_context
*subflow
= mptcp_subflow_ctx(sk
);
831 struct mptcp_sock
*msk
= mptcp_sk(subflow
->conn
);
832 struct mptcp_options_received mp_opt
;
833 struct mptcp_ext
*mpext
;
835 if (__mptcp_check_fallback(msk
))
838 mptcp_get_options(skb
, &mp_opt
);
839 if (!check_fully_established(msk
, sk
, subflow
, skb
, &mp_opt
))
842 if (mp_opt
.add_addr
&& add_addr_hmac_valid(msk
, &mp_opt
)) {
843 struct mptcp_addr_info addr
;
845 addr
.port
= htons(mp_opt
.port
);
846 addr
.id
= mp_opt
.addr_id
;
847 if (mp_opt
.family
== MPTCP_ADDR_IPVERSION_4
) {
848 addr
.family
= AF_INET
;
849 addr
.addr
= mp_opt
.addr
;
851 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
852 else if (mp_opt
.family
== MPTCP_ADDR_IPVERSION_6
) {
853 addr
.family
= AF_INET6
;
854 addr
.addr6
= mp_opt
.addr6
;
858 mptcp_pm_add_addr_received(msk
, &addr
);
865 /* we can't wait for recvmsg() to update the ack_seq, otherwise
866 * monodirectional flows will stuck
869 update_una(msk
, &mp_opt
);
871 /* Zero-data-length packets are dropped by the caller and not
872 * propagated to the MPTCP layer, so the skb extension does not
873 * need to be allocated or populated. DATA_FIN information, if
874 * present, needs to be updated here before the skb is freed.
876 if (TCP_SKB_CB(skb
)->seq
== TCP_SKB_CB(skb
)->end_seq
) {
877 if (mp_opt
.data_fin
&& mp_opt
.data_len
== 1 &&
878 mptcp_update_rcv_data_fin(msk
, mp_opt
.data_seq
) &&
879 schedule_work(&msk
->work
))
880 sock_hold(subflow
->conn
);
885 mpext
= skb_ext_add(skb
, SKB_EXT_MPTCP
);
889 memset(mpext
, 0, sizeof(*mpext
));
891 if (mp_opt
.use_map
) {
892 if (mp_opt
.mpc_map
) {
893 /* this is an MP_CAPABLE carrying MPTCP data
894 * we know this map the first chunk of data
896 mptcp_crypto_key_sha(subflow
->remote_key
, NULL
,
899 mpext
->subflow_seq
= 1;
904 mpext
->data_seq
= mp_opt
.data_seq
;
905 mpext
->subflow_seq
= mp_opt
.subflow_seq
;
906 mpext
->dsn64
= mp_opt
.dsn64
;
907 mpext
->data_fin
= mp_opt
.data_fin
;
909 mpext
->data_len
= mp_opt
.data_len
;
914 void mptcp_write_options(__be32
*ptr
, struct mptcp_out_options
*opts
)
916 if ((OPTION_MPTCP_MPC_SYN
| OPTION_MPTCP_MPC_SYNACK
|
917 OPTION_MPTCP_MPC_ACK
) & opts
->suboptions
) {
920 if (OPTION_MPTCP_MPC_SYN
& opts
->suboptions
)
921 len
= TCPOLEN_MPTCP_MPC_SYN
;
922 else if (OPTION_MPTCP_MPC_SYNACK
& opts
->suboptions
)
923 len
= TCPOLEN_MPTCP_MPC_SYNACK
;
924 else if (opts
->ext_copy
.data_len
)
925 len
= TCPOLEN_MPTCP_MPC_ACK_DATA
;
927 len
= TCPOLEN_MPTCP_MPC_ACK
;
929 *ptr
++ = mptcp_option(MPTCPOPT_MP_CAPABLE
, len
,
930 MPTCP_SUPPORTED_VERSION
,
931 MPTCP_CAP_HMAC_SHA256
);
933 if (!((OPTION_MPTCP_MPC_SYNACK
| OPTION_MPTCP_MPC_ACK
) &
935 goto mp_capable_done
;
937 put_unaligned_be64(opts
->sndr_key
, ptr
);
939 if (!((OPTION_MPTCP_MPC_ACK
) & opts
->suboptions
))
940 goto mp_capable_done
;
942 put_unaligned_be64(opts
->rcvr_key
, ptr
);
944 if (!opts
->ext_copy
.data_len
)
945 goto mp_capable_done
;
947 put_unaligned_be32(opts
->ext_copy
.data_len
<< 16 |
948 TCPOPT_NOP
<< 8 | TCPOPT_NOP
, ptr
);
953 if (OPTION_MPTCP_ADD_ADDR
& opts
->suboptions
) {
955 *ptr
++ = mptcp_option(MPTCPOPT_ADD_ADDR
,
956 TCPOLEN_MPTCP_ADD_ADDR
, 0,
959 *ptr
++ = mptcp_option(MPTCPOPT_ADD_ADDR
,
960 TCPOLEN_MPTCP_ADD_ADDR_BASE
,
963 memcpy((u8
*)ptr
, (u8
*)&opts
->addr
.s_addr
, 4);
966 put_unaligned_be64(opts
->ahmac
, ptr
);
971 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
972 if (OPTION_MPTCP_ADD_ADDR6
& opts
->suboptions
) {
974 *ptr
++ = mptcp_option(MPTCPOPT_ADD_ADDR
,
975 TCPOLEN_MPTCP_ADD_ADDR6
, 0,
978 *ptr
++ = mptcp_option(MPTCPOPT_ADD_ADDR
,
979 TCPOLEN_MPTCP_ADD_ADDR6_BASE
,
982 memcpy((u8
*)ptr
, opts
->addr6
.s6_addr
, 16);
985 put_unaligned_be64(opts
->ahmac
, ptr
);
991 if (OPTION_MPTCP_RM_ADDR
& opts
->suboptions
) {
992 *ptr
++ = mptcp_option(MPTCPOPT_RM_ADDR
,
993 TCPOLEN_MPTCP_RM_ADDR_BASE
,
997 if (OPTION_MPTCP_MPJ_SYN
& opts
->suboptions
) {
998 *ptr
++ = mptcp_option(MPTCPOPT_MP_JOIN
,
999 TCPOLEN_MPTCP_MPJ_SYN
,
1000 opts
->backup
, opts
->join_id
);
1001 put_unaligned_be32(opts
->token
, ptr
);
1003 put_unaligned_be32(opts
->nonce
, ptr
);
1007 if (OPTION_MPTCP_MPJ_SYNACK
& opts
->suboptions
) {
1008 *ptr
++ = mptcp_option(MPTCPOPT_MP_JOIN
,
1009 TCPOLEN_MPTCP_MPJ_SYNACK
,
1010 opts
->backup
, opts
->join_id
);
1011 put_unaligned_be64(opts
->thmac
, ptr
);
1013 put_unaligned_be32(opts
->nonce
, ptr
);
1017 if (OPTION_MPTCP_MPJ_ACK
& opts
->suboptions
) {
1018 *ptr
++ = mptcp_option(MPTCPOPT_MP_JOIN
,
1019 TCPOLEN_MPTCP_MPJ_ACK
, 0, 0);
1020 memcpy(ptr
, opts
->hmac
, MPTCPOPT_HMAC_LEN
);
1024 if (opts
->ext_copy
.use_ack
|| opts
->ext_copy
.use_map
) {
1025 struct mptcp_ext
*mpext
= &opts
->ext_copy
;
1026 u8 len
= TCPOLEN_MPTCP_DSS_BASE
;
1029 if (mpext
->use_ack
) {
1030 flags
= MPTCP_DSS_HAS_ACK
;
1032 len
+= TCPOLEN_MPTCP_DSS_ACK64
;
1033 flags
|= MPTCP_DSS_ACK64
;
1035 len
+= TCPOLEN_MPTCP_DSS_ACK32
;
1039 if (mpext
->use_map
) {
1040 len
+= TCPOLEN_MPTCP_DSS_MAP64
;
1042 /* Use only 64-bit mapping flags for now, add
1043 * support for optional 32-bit mappings later.
1045 flags
|= MPTCP_DSS_HAS_MAP
| MPTCP_DSS_DSN64
;
1046 if (mpext
->data_fin
)
1047 flags
|= MPTCP_DSS_DATA_FIN
;
1050 *ptr
++ = mptcp_option(MPTCPOPT_DSS
, len
, 0, flags
);
1052 if (mpext
->use_ack
) {
1054 put_unaligned_be64(mpext
->data_ack
, ptr
);
1057 put_unaligned_be32(mpext
->data_ack32
, ptr
);
1062 if (mpext
->use_map
) {
1063 put_unaligned_be64(mpext
->data_seq
, ptr
);
1065 put_unaligned_be32(mpext
->subflow_seq
, ptr
);
1067 put_unaligned_be32(mpext
->data_len
<< 16 |
1068 TCPOPT_NOP
<< 8 | TCPOPT_NOP
, ptr
);