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
mptcp_cap_flag_sha256(u8 flags)18 static bool mptcp_cap_flag_sha256(u8 flags)
19 {
20 return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
21 }
22
mptcp_parse_option(const struct sk_buff * skb,const unsigned char * ptr,int opsize,struct mptcp_options_received * mp_opt)23 static 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->suboptions |= OPTION_MPTCP_CSUMREQD;
85
86 mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0);
87
88 mp_opt->suboptions |= OPTIONS_MPTCP_MPC;
89 if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
90 mp_opt->sndr_key = get_unaligned_be64(ptr);
91 ptr += 8;
92 }
93 if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
94 mp_opt->rcvr_key = get_unaligned_be64(ptr);
95 ptr += 8;
96 }
97 if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) {
98 /* Section 3.1.:
99 * "the data parameters in a MP_CAPABLE are semantically
100 * equivalent to those in a DSS option and can be used
101 * interchangeably."
102 */
103 mp_opt->suboptions |= OPTION_MPTCP_DSS;
104 mp_opt->use_map = 1;
105 mp_opt->mpc_map = 1;
106 mp_opt->use_ack = 0;
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 = get_unaligned((__force __sum16 *)ptr);
112 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
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 if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
122 mp_opt->suboptions |= OPTION_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->suboptions |= OPTION_MPTCP_MPJ_SYNACK;
134 mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
135 mp_opt->join_id = *ptr++;
136 mp_opt->thmac = get_unaligned_be64(ptr);
137 ptr += 8;
138 mp_opt->nonce = get_unaligned_be32(ptr);
139 ptr += 4;
140 pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
141 mp_opt->backup, mp_opt->join_id,
142 mp_opt->thmac, mp_opt->nonce);
143 } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
144 mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK;
145 ptr += 2;
146 memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
147 pr_debug("MP_JOIN hmac");
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->suboptions |= OPTION_MPTCP_DSS;
196 if (mp_opt->use_ack) {
197 if (mp_opt->ack64) {
198 mp_opt->data_ack = get_unaligned_be64(ptr);
199 ptr += 8;
200 } else {
201 mp_opt->data_ack = get_unaligned_be32(ptr);
202 ptr += 4;
203 }
204
205 pr_debug("data_ack=%llu", mp_opt->data_ack);
206 }
207
208 if (mp_opt->use_map) {
209 if (mp_opt->dsn64) {
210 mp_opt->data_seq = get_unaligned_be64(ptr);
211 ptr += 8;
212 } else {
213 mp_opt->data_seq = get_unaligned_be32(ptr);
214 ptr += 4;
215 }
216
217 mp_opt->subflow_seq = get_unaligned_be32(ptr);
218 ptr += 4;
219
220 mp_opt->data_len = get_unaligned_be16(ptr);
221 ptr += 2;
222
223 if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) {
224 mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
225 mp_opt->csum = get_unaligned((__force __sum16 *)ptr);
226 ptr += 2;
227 }
228
229 pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
230 mp_opt->data_seq, mp_opt->subflow_seq,
231 mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD),
232 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->suboptions |= OPTION_MPTCP_ADD_ADDR;
264 mp_opt->addr.id = *ptr++;
265 mp_opt->addr.port = 0;
266 mp_opt->ahmac = 0;
267 if (mp_opt->addr.family == AF_INET) {
268 memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);
269 ptr += 4;
270 if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
271 opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
272 mp_opt->addr.port = htons(get_unaligned_be16(ptr));
273 ptr += 2;
274 }
275 }
276 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
277 else {
278 memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16);
279 ptr += 16;
280 if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
281 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
282 mp_opt->addr.port = htons(get_unaligned_be16(ptr));
283 ptr += 2;
284 }
285 }
286 #endif
287 if (!mp_opt->echo) {
288 mp_opt->ahmac = get_unaligned_be64(ptr);
289 ptr += 8;
290 }
291 pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
292 (mp_opt->addr.family == AF_INET6) ? "6" : "",
293 mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port));
294 break;
295
296 case MPTCPOPT_RM_ADDR:
297 if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 ||
298 opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX)
299 break;
300
301 ptr++;
302
303 mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR;
304 mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;
305 for (i = 0; i < mp_opt->rm_list.nr; i++)
306 mp_opt->rm_list.ids[i] = *ptr++;
307 pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr);
308 break;
309
310 case MPTCPOPT_MP_PRIO:
311 if (opsize != TCPOLEN_MPTCP_PRIO)
312 break;
313
314 mp_opt->suboptions |= OPTION_MPTCP_PRIO;
315 mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
316 pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
317 break;
318
319 case MPTCPOPT_MP_FASTCLOSE:
320 if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
321 break;
322
323 ptr += 2;
324 mp_opt->rcvr_key = get_unaligned_be64(ptr);
325 ptr += 8;
326 mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE;
327 break;
328
329 case MPTCPOPT_RST:
330 if (opsize != TCPOLEN_MPTCP_RST)
331 break;
332
333 if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
334 break;
335
336 mp_opt->suboptions |= OPTION_MPTCP_RST;
337 flags = *ptr++;
338 mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
339 mp_opt->reset_reason = *ptr;
340 break;
341
342 case MPTCPOPT_MP_FAIL:
343 if (opsize != TCPOLEN_MPTCP_FAIL)
344 break;
345
346 ptr += 2;
347 mp_opt->suboptions |= OPTION_MPTCP_FAIL;
348 mp_opt->fail_seq = get_unaligned_be64(ptr);
349 pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);
350 break;
351
352 default:
353 break;
354 }
355 }
356
mptcp_get_options(const struct sk_buff * skb,struct mptcp_options_received * mp_opt)357 void mptcp_get_options(const struct sk_buff *skb,
358 struct mptcp_options_received *mp_opt)
359 {
360 const struct tcphdr *th = tcp_hdr(skb);
361 const unsigned char *ptr;
362 int length;
363
364 /* initialize option status */
365 mp_opt->suboptions = 0;
366
367 length = (th->doff * 4) - sizeof(struct tcphdr);
368 ptr = (const unsigned char *)(th + 1);
369
370 while (length > 0) {
371 int opcode = *ptr++;
372 int opsize;
373
374 switch (opcode) {
375 case TCPOPT_EOL:
376 return;
377 case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
378 length--;
379 continue;
380 default:
381 if (length < 2)
382 return;
383 opsize = *ptr++;
384 if (opsize < 2) /* "silly options" */
385 return;
386 if (opsize > length)
387 return; /* don't parse partial options */
388 if (opcode == TCPOPT_MPTCP)
389 mptcp_parse_option(skb, ptr, opsize, mp_opt);
390 ptr += opsize - 2;
391 length -= opsize;
392 }
393 }
394 }
395
mptcp_syn_options(struct sock * sk,const struct sk_buff * skb,unsigned int * size,struct mptcp_out_options * opts)396 bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
397 unsigned int *size, struct mptcp_out_options *opts)
398 {
399 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
400
401 /* we will use snd_isn to detect first pkt [re]transmission
402 * in mptcp_established_options_mp()
403 */
404 subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
405 if (subflow->request_mptcp) {
406 opts->suboptions = OPTION_MPTCP_MPC_SYN;
407 opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk));
408 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
409 *size = TCPOLEN_MPTCP_MPC_SYN;
410 return true;
411 } else if (subflow->request_join) {
412 pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
413 subflow->local_nonce);
414 opts->suboptions = OPTION_MPTCP_MPJ_SYN;
415 opts->join_id = subflow->local_id;
416 opts->token = subflow->remote_token;
417 opts->nonce = subflow->local_nonce;
418 opts->backup = subflow->request_bkup;
419 *size = TCPOLEN_MPTCP_MPJ_SYN;
420 return true;
421 }
422 return false;
423 }
424
clear_3rdack_retransmission(struct sock * sk)425 static void clear_3rdack_retransmission(struct sock *sk)
426 {
427 struct inet_connection_sock *icsk = inet_csk(sk);
428
429 sk_stop_timer(sk, &icsk->icsk_delack_timer);
430 icsk->icsk_ack.timeout = 0;
431 icsk->icsk_ack.ato = 0;
432 icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
433 }
434
mptcp_established_options_mp(struct sock * sk,struct sk_buff * skb,bool snd_data_fin_enable,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)435 static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
436 bool snd_data_fin_enable,
437 unsigned int *size,
438 unsigned int remaining,
439 struct mptcp_out_options *opts)
440 {
441 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
442 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
443 struct mptcp_ext *mpext;
444 unsigned int data_len;
445 u8 len;
446
447 /* When skb is not available, we better over-estimate the emitted
448 * options len. A full DSS option (28 bytes) is longer than
449 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
450 * tell the caller to defer the estimate to
451 * mptcp_established_options_dss(), which will reserve enough space.
452 */
453 if (!skb)
454 return false;
455
456 /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
457 if (subflow->fully_established || snd_data_fin_enable ||
458 subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
459 sk->sk_state != TCP_ESTABLISHED)
460 return false;
461
462 if (subflow->mp_capable) {
463 mpext = mptcp_get_ext(skb);
464 data_len = mpext ? mpext->data_len : 0;
465
466 /* we will check ops->data_len in mptcp_write_options() to
467 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
468 * TCPOLEN_MPTCP_MPC_ACK
469 */
470 opts->data_len = data_len;
471 opts->suboptions = OPTION_MPTCP_MPC_ACK;
472 opts->sndr_key = subflow->local_key;
473 opts->rcvr_key = subflow->remote_key;
474 opts->csum_reqd = READ_ONCE(msk->csum_enabled);
475 opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
476
477 /* Section 3.1.
478 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
479 * packets that start the first subflow of an MPTCP connection,
480 * as well as the first packet that carries data
481 */
482 if (data_len > 0) {
483 len = TCPOLEN_MPTCP_MPC_ACK_DATA;
484 if (opts->csum_reqd) {
485 /* we need to propagate more info to csum the pseudo hdr */
486 opts->data_seq = mpext->data_seq;
487 opts->subflow_seq = mpext->subflow_seq;
488 opts->csum = mpext->csum;
489 len += TCPOLEN_MPTCP_DSS_CHECKSUM;
490 }
491 *size = ALIGN(len, 4);
492 } else {
493 *size = TCPOLEN_MPTCP_MPC_ACK;
494 }
495
496 pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
497 subflow, subflow->local_key, subflow->remote_key,
498 data_len);
499
500 return true;
501 } else if (subflow->mp_join) {
502 opts->suboptions = OPTION_MPTCP_MPJ_ACK;
503 memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
504 *size = TCPOLEN_MPTCP_MPJ_ACK;
505 pr_debug("subflow=%p", subflow);
506
507 /* we can use the full delegate action helper only from BH context
508 * If we are in process context - sk is flushing the backlog at
509 * socket lock release time - just set the appropriate flag, will
510 * be handled by the release callback
511 */
512 if (sock_owned_by_user(sk))
513 set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status);
514 else
515 mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK);
516 return true;
517 }
518 return false;
519 }
520
mptcp_write_data_fin(struct mptcp_subflow_context * subflow,struct sk_buff * skb,struct mptcp_ext * ext)521 static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
522 struct sk_buff *skb, struct mptcp_ext *ext)
523 {
524 /* The write_seq value has already been incremented, so the actual
525 * sequence number for the DATA_FIN is one less.
526 */
527 u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
528
529 if (!ext->use_map || !skb->len) {
530 /* RFC6824 requires a DSS mapping with specific values
531 * if DATA_FIN is set but no data payload is mapped
532 */
533 ext->data_fin = 1;
534 ext->use_map = 1;
535 ext->dsn64 = 1;
536 ext->data_seq = data_fin_tx_seq;
537 ext->subflow_seq = 0;
538 ext->data_len = 1;
539 } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
540 /* If there's an existing DSS mapping and it is the
541 * final mapping, DATA_FIN consumes 1 additional byte of
542 * mapping space.
543 */
544 ext->data_fin = 1;
545 ext->data_len++;
546 }
547 }
548
mptcp_established_options_dss(struct sock * sk,struct sk_buff * skb,bool snd_data_fin_enable,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)549 static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
550 bool snd_data_fin_enable,
551 unsigned int *size,
552 unsigned int remaining,
553 struct mptcp_out_options *opts)
554 {
555 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
556 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
557 unsigned int dss_size = 0;
558 struct mptcp_ext *mpext;
559 unsigned int ack_size;
560 bool ret = false;
561 u64 ack_seq;
562
563 opts->csum_reqd = READ_ONCE(msk->csum_enabled);
564 mpext = skb ? mptcp_get_ext(skb) : NULL;
565
566 if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
567 unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
568
569 if (mpext) {
570 if (opts->csum_reqd)
571 map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;
572
573 opts->ext_copy = *mpext;
574 }
575
576 remaining -= map_size;
577 dss_size = map_size;
578 if (skb && snd_data_fin_enable)
579 mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
580 opts->suboptions = OPTION_MPTCP_DSS;
581 ret = true;
582 }
583
584 /* passive sockets msk will set the 'can_ack' after accept(), even
585 * if the first subflow may have the already the remote key handy
586 */
587 opts->ext_copy.use_ack = 0;
588 if (!READ_ONCE(msk->can_ack)) {
589 *size = ALIGN(dss_size, 4);
590 return ret;
591 }
592
593 ack_seq = READ_ONCE(msk->ack_seq);
594 if (READ_ONCE(msk->use_64bit_ack)) {
595 ack_size = TCPOLEN_MPTCP_DSS_ACK64;
596 opts->ext_copy.data_ack = ack_seq;
597 opts->ext_copy.ack64 = 1;
598 } else {
599 ack_size = TCPOLEN_MPTCP_DSS_ACK32;
600 opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
601 opts->ext_copy.ack64 = 0;
602 }
603 opts->ext_copy.use_ack = 1;
604 opts->suboptions = OPTION_MPTCP_DSS;
605 WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
606
607 /* Add kind/length/subtype/flag overhead if mapping is not populated */
608 if (dss_size == 0)
609 ack_size += TCPOLEN_MPTCP_DSS_BASE;
610
611 dss_size += ack_size;
612
613 *size = ALIGN(dss_size, 4);
614 return true;
615 }
616
add_addr_generate_hmac(u64 key1,u64 key2,struct mptcp_addr_info * addr)617 static u64 add_addr_generate_hmac(u64 key1, u64 key2,
618 struct mptcp_addr_info *addr)
619 {
620 u16 port = ntohs(addr->port);
621 u8 hmac[SHA256_DIGEST_SIZE];
622 u8 msg[19];
623 int i = 0;
624
625 msg[i++] = addr->id;
626 if (addr->family == AF_INET) {
627 memcpy(&msg[i], &addr->addr.s_addr, 4);
628 i += 4;
629 }
630 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
631 else if (addr->family == AF_INET6) {
632 memcpy(&msg[i], &addr->addr6.s6_addr, 16);
633 i += 16;
634 }
635 #endif
636 msg[i++] = port >> 8;
637 msg[i++] = port & 0xFF;
638
639 mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac);
640
641 return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
642 }
643
mptcp_established_options_add_addr(struct sock * sk,struct sk_buff * skb,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)644 static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
645 unsigned int *size,
646 unsigned int remaining,
647 struct mptcp_out_options *opts)
648 {
649 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
650 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
651 bool drop_other_suboptions = false;
652 unsigned int opt_size = *size;
653 bool echo;
654 bool port;
655 int len;
656
657 /* add addr will strip the existing options, be sure to avoid breaking
658 * MPC/MPJ handshakes
659 */
660 if (!mptcp_pm_should_add_signal(msk) ||
661 (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) ||
662 !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr,
663 &echo, &port, &drop_other_suboptions))
664 return false;
665
666 if (drop_other_suboptions)
667 remaining += opt_size;
668 len = mptcp_add_addr_len(opts->addr.family, echo, port);
669 if (remaining < len)
670 return false;
671
672 *size = len;
673 if (drop_other_suboptions) {
674 pr_debug("drop other suboptions");
675 opts->suboptions = 0;
676
677 /* note that e.g. DSS could have written into the memory
678 * aliased by ahmac, we must reset the field here
679 * to avoid appending the hmac even for ADD_ADDR echo
680 * options
681 */
682 opts->ahmac = 0;
683 *size -= opt_size;
684 }
685 opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
686 if (!echo) {
687 opts->ahmac = add_addr_generate_hmac(msk->local_key,
688 msk->remote_key,
689 &opts->addr);
690 }
691 pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
692 opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
693
694 return true;
695 }
696
mptcp_established_options_rm_addr(struct sock * sk,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)697 static bool mptcp_established_options_rm_addr(struct sock *sk,
698 unsigned int *size,
699 unsigned int remaining,
700 struct mptcp_out_options *opts)
701 {
702 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
703 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
704 struct mptcp_rm_list rm_list;
705 int i, len;
706
707 if (!mptcp_pm_should_rm_signal(msk) ||
708 !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list)))
709 return false;
710
711 len = mptcp_rm_addr_len(&rm_list);
712 if (len < 0)
713 return false;
714 if (remaining < len)
715 return false;
716
717 *size = len;
718 opts->suboptions |= OPTION_MPTCP_RM_ADDR;
719 opts->rm_list = rm_list;
720
721 for (i = 0; i < opts->rm_list.nr; i++)
722 pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]);
723
724 return true;
725 }
726
mptcp_established_options_mp_prio(struct sock * sk,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)727 static bool mptcp_established_options_mp_prio(struct sock *sk,
728 unsigned int *size,
729 unsigned int remaining,
730 struct mptcp_out_options *opts)
731 {
732 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
733
734 /* can't send MP_PRIO with MPC, as they share the same option space:
735 * 'backup'. Also it makes no sense at all
736 */
737 if (!subflow->send_mp_prio ||
738 ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
739 OPTION_MPTCP_MPC_ACK) & opts->suboptions))
740 return false;
741
742 /* account for the trailing 'nop' option */
743 if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
744 return false;
745
746 *size = TCPOLEN_MPTCP_PRIO_ALIGN;
747 opts->suboptions |= OPTION_MPTCP_PRIO;
748 opts->backup = subflow->request_bkup;
749
750 pr_debug("prio=%d", opts->backup);
751
752 return true;
753 }
754
mptcp_established_options_rst(struct sock * sk,struct sk_buff * skb,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)755 static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
756 unsigned int *size,
757 unsigned int remaining,
758 struct mptcp_out_options *opts)
759 {
760 const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
761
762 if (remaining < TCPOLEN_MPTCP_RST)
763 return false;
764
765 *size = TCPOLEN_MPTCP_RST;
766 opts->suboptions |= OPTION_MPTCP_RST;
767 opts->reset_transient = subflow->reset_transient;
768 opts->reset_reason = subflow->reset_reason;
769
770 return true;
771 }
772
mptcp_established_options_mp_fail(struct sock * sk,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)773 static bool mptcp_established_options_mp_fail(struct sock *sk,
774 unsigned int *size,
775 unsigned int remaining,
776 struct mptcp_out_options *opts)
777 {
778 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
779
780 if (likely(!subflow->send_mp_fail))
781 return false;
782
783 if (remaining < TCPOLEN_MPTCP_FAIL)
784 return false;
785
786 *size = TCPOLEN_MPTCP_FAIL;
787 opts->suboptions |= OPTION_MPTCP_FAIL;
788 opts->fail_seq = subflow->map_seq;
789
790 pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq);
791
792 return true;
793 }
794
mptcp_established_options(struct sock * sk,struct sk_buff * skb,unsigned int * size,unsigned int remaining,struct mptcp_out_options * opts)795 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
796 unsigned int *size, unsigned int remaining,
797 struct mptcp_out_options *opts)
798 {
799 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
800 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
801 unsigned int opt_size = 0;
802 bool snd_data_fin;
803 bool ret = false;
804
805 opts->suboptions = 0;
806
807 if (unlikely(__mptcp_check_fallback(msk)))
808 return false;
809
810 if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
811 if (mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
812 *size += opt_size;
813 remaining -= opt_size;
814 }
815 if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) {
816 *size += opt_size;
817 remaining -= opt_size;
818 }
819 return true;
820 }
821
822 snd_data_fin = mptcp_data_fin_enabled(msk);
823 if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, remaining, opts))
824 ret = true;
825 else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, remaining, opts)) {
826 unsigned int mp_fail_size;
827
828 ret = true;
829 if (mptcp_established_options_mp_fail(sk, &mp_fail_size,
830 remaining - opt_size, opts)) {
831 *size += opt_size + mp_fail_size;
832 remaining -= opt_size - mp_fail_size;
833 return true;
834 }
835 }
836
837 /* we reserved enough space for the above options, and exceeding the
838 * TCP option space would be fatal
839 */
840 if (WARN_ON_ONCE(opt_size > remaining))
841 return false;
842
843 *size += opt_size;
844 remaining -= opt_size;
845 if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
846 *size += opt_size;
847 remaining -= opt_size;
848 ret = true;
849 } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
850 *size += opt_size;
851 remaining -= opt_size;
852 ret = true;
853 }
854
855 if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
856 *size += opt_size;
857 remaining -= opt_size;
858 ret = true;
859 }
860
861 return ret;
862 }
863
mptcp_synack_options(const struct request_sock * req,unsigned int * size,struct mptcp_out_options * opts)864 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
865 struct mptcp_out_options *opts)
866 {
867 struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
868
869 if (subflow_req->mp_capable) {
870 opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
871 opts->sndr_key = subflow_req->local_key;
872 opts->csum_reqd = subflow_req->csum_reqd;
873 opts->allow_join_id0 = subflow_req->allow_join_id0;
874 *size = TCPOLEN_MPTCP_MPC_SYNACK;
875 pr_debug("subflow_req=%p, local_key=%llu",
876 subflow_req, subflow_req->local_key);
877 return true;
878 } else if (subflow_req->mp_join) {
879 opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
880 opts->backup = subflow_req->backup;
881 opts->join_id = subflow_req->local_id;
882 opts->thmac = subflow_req->thmac;
883 opts->nonce = subflow_req->local_nonce;
884 pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
885 subflow_req, opts->backup, opts->join_id,
886 opts->thmac, opts->nonce);
887 *size = TCPOLEN_MPTCP_MPJ_SYNACK;
888 return true;
889 }
890 return false;
891 }
892
check_fully_established(struct mptcp_sock * msk,struct sock * ssk,struct mptcp_subflow_context * subflow,struct sk_buff * skb,struct mptcp_options_received * mp_opt)893 static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
894 struct mptcp_subflow_context *subflow,
895 struct sk_buff *skb,
896 struct mptcp_options_received *mp_opt)
897 {
898 /* here we can process OoO, in-window pkts, only in-sequence 4th ack
899 * will make the subflow fully established
900 */
901 if (likely(subflow->fully_established)) {
902 /* on passive sockets, check for 3rd ack retransmission
903 * note that msk is always set by subflow_syn_recv_sock()
904 * for mp_join subflows
905 */
906 if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
907 TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
908 subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) &&
909 READ_ONCE(msk->pm.server_side))
910 tcp_send_ack(ssk);
911 goto fully_established;
912 }
913
914 /* we must process OoO packets before the first subflow is fully
915 * established. OoO packets are instead a protocol violation
916 * for MP_JOIN subflows as the peer must not send any data
917 * before receiving the forth ack - cfr. RFC 8684 section 3.2.
918 */
919 if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
920 if (subflow->mp_join)
921 goto reset;
922 return subflow->mp_capable;
923 }
924
925 if (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||
926 ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo)) {
927 /* subflows are fully established as soon as we get any
928 * additional ack, including ADD_ADDR.
929 */
930 subflow->fully_established = 1;
931 WRITE_ONCE(msk->fully_established, true);
932 goto fully_established;
933 }
934
935 /* If the first established packet does not contain MP_CAPABLE + data
936 * then fallback to TCP. Fallback scenarios requires a reset for
937 * MP_JOIN subflows.
938 */
939 if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) {
940 if (subflow->mp_join)
941 goto reset;
942 subflow->mp_capable = 0;
943 pr_fallback(msk);
944 __mptcp_do_fallback(msk);
945 return false;
946 }
947
948 if (mp_opt->deny_join_id0)
949 WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
950
951 if (unlikely(!READ_ONCE(msk->pm.server_side)))
952 pr_warn_once("bogus mpc option on established client sk");
953 mptcp_subflow_fully_established(subflow, mp_opt);
954
955 fully_established:
956 /* if the subflow is not already linked into the conn_list, we can't
957 * notify the PM: this subflow is still on the listener queue
958 * and the PM possibly acquiring the subflow lock could race with
959 * the listener close
960 */
961 if (likely(subflow->pm_notified) || list_empty(&subflow->node))
962 return true;
963
964 subflow->pm_notified = 1;
965 if (subflow->mp_join) {
966 clear_3rdack_retransmission(ssk);
967 mptcp_pm_subflow_established(msk);
968 } else {
969 mptcp_pm_fully_established(msk, ssk, GFP_ATOMIC);
970 }
971 return true;
972
973 reset:
974 mptcp_subflow_reset(ssk);
975 return false;
976 }
977
__mptcp_expand_seq(u64 old_seq,u64 cur_seq)978 u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq)
979 {
980 u32 old_seq32, cur_seq32;
981
982 old_seq32 = (u32)old_seq;
983 cur_seq32 = (u32)cur_seq;
984 cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32;
985 if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32)))
986 return cur_seq + (1LL << 32);
987
988 /* reverse wrap could happen, too */
989 if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32)))
990 return cur_seq - (1LL << 32);
991 return cur_seq;
992 }
993
ack_update_msk(struct mptcp_sock * msk,struct sock * ssk,struct mptcp_options_received * mp_opt)994 static void ack_update_msk(struct mptcp_sock *msk,
995 struct sock *ssk,
996 struct mptcp_options_received *mp_opt)
997 {
998 u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
999 struct sock *sk = (struct sock *)msk;
1000 u64 old_snd_una;
1001
1002 mptcp_data_lock(sk);
1003
1004 /* avoid ack expansion on update conflict, to reduce the risk of
1005 * wrongly expanding to a future ack sequence number, which is way
1006 * more dangerous than missing an ack
1007 */
1008 old_snd_una = msk->snd_una;
1009 new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
1010
1011 /* ACK for data not even sent yet? Ignore.*/
1012 if (unlikely(after64(new_snd_una, snd_nxt)))
1013 new_snd_una = old_snd_una;
1014
1015 new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
1016
1017 if (after64(new_wnd_end, msk->wnd_end))
1018 msk->wnd_end = new_wnd_end;
1019
1020 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
1021 if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
1022 __mptcp_check_push(sk, ssk);
1023
1024 if (after64(new_snd_una, old_snd_una)) {
1025 msk->snd_una = new_snd_una;
1026 __mptcp_data_acked(sk);
1027 }
1028 mptcp_data_unlock(sk);
1029
1030 trace_ack_update_msk(mp_opt->data_ack,
1031 old_snd_una, new_snd_una,
1032 new_wnd_end, msk->wnd_end);
1033 }
1034
mptcp_update_rcv_data_fin(struct mptcp_sock * msk,u64 data_fin_seq,bool use_64bit)1035 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
1036 {
1037 /* Skip if DATA_FIN was already received.
1038 * If updating simultaneously with the recvmsg loop, values
1039 * should match. If they mismatch, the peer is misbehaving and
1040 * we will prefer the most recent information.
1041 */
1042 if (READ_ONCE(msk->rcv_data_fin))
1043 return false;
1044
1045 WRITE_ONCE(msk->rcv_data_fin_seq,
1046 mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
1047 WRITE_ONCE(msk->rcv_data_fin, 1);
1048
1049 return true;
1050 }
1051
add_addr_hmac_valid(struct mptcp_sock * msk,struct mptcp_options_received * mp_opt)1052 static bool add_addr_hmac_valid(struct mptcp_sock *msk,
1053 struct mptcp_options_received *mp_opt)
1054 {
1055 u64 hmac = 0;
1056
1057 if (mp_opt->echo)
1058 return true;
1059
1060 hmac = add_addr_generate_hmac(msk->remote_key,
1061 msk->local_key,
1062 &mp_opt->addr);
1063
1064 pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
1065 msk, (unsigned long long)hmac,
1066 (unsigned long long)mp_opt->ahmac);
1067
1068 return hmac == mp_opt->ahmac;
1069 }
1070
1071 /* Return false if a subflow has been reset, else return true */
mptcp_incoming_options(struct sock * sk,struct sk_buff * skb)1072 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
1073 {
1074 struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
1075 struct mptcp_sock *msk = mptcp_sk(subflow->conn);
1076 struct mptcp_options_received mp_opt;
1077 struct mptcp_ext *mpext;
1078
1079 if (__mptcp_check_fallback(msk)) {
1080 /* Keep it simple and unconditionally trigger send data cleanup and
1081 * pending queue spooling. We will need to acquire the data lock
1082 * for more accurate checks, and once the lock is acquired, such
1083 * helpers are cheap.
1084 */
1085 mptcp_data_lock(subflow->conn);
1086 if (sk_stream_memory_free(sk))
1087 __mptcp_check_push(subflow->conn, sk);
1088 __mptcp_data_acked(subflow->conn);
1089 mptcp_data_unlock(subflow->conn);
1090 return true;
1091 }
1092
1093 mptcp_get_options(skb, &mp_opt);
1094
1095 /* The subflow can be in close state only if check_fully_established()
1096 * just sent a reset. If so, tell the caller to ignore the current packet.
1097 */
1098 if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
1099 return sk->sk_state != TCP_CLOSE;
1100
1101 if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) {
1102 if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) &&
1103 msk->local_key == mp_opt.rcvr_key) {
1104 WRITE_ONCE(msk->rcv_fastclose, true);
1105 mptcp_schedule_work((struct sock *)msk);
1106 }
1107
1108 if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) &&
1109 add_addr_hmac_valid(msk, &mp_opt)) {
1110 if (!mp_opt.echo) {
1111 mptcp_pm_add_addr_received(msk, &mp_opt.addr);
1112 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
1113 } else {
1114 mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);
1115 mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);
1116 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
1117 }
1118
1119 if (mp_opt.addr.port)
1120 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
1121 }
1122
1123 if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR)
1124 mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);
1125
1126 if (mp_opt.suboptions & OPTION_MPTCP_PRIO) {
1127 mptcp_pm_mp_prio_received(sk, mp_opt.backup);
1128 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
1129 }
1130
1131 if (mp_opt.suboptions & OPTION_MPTCP_FAIL) {
1132 mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
1133 MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX);
1134 }
1135
1136 if (mp_opt.suboptions & OPTION_MPTCP_RST) {
1137 subflow->reset_seen = 1;
1138 subflow->reset_reason = mp_opt.reset_reason;
1139 subflow->reset_transient = mp_opt.reset_transient;
1140 }
1141
1142 if (!(mp_opt.suboptions & OPTION_MPTCP_DSS))
1143 return true;
1144 }
1145
1146 /* we can't wait for recvmsg() to update the ack_seq, otherwise
1147 * monodirectional flows will stuck
1148 */
1149 if (mp_opt.use_ack)
1150 ack_update_msk(msk, sk, &mp_opt);
1151
1152 /* Zero-data-length packets are dropped by the caller and not
1153 * propagated to the MPTCP layer, so the skb extension does not
1154 * need to be allocated or populated. DATA_FIN information, if
1155 * present, needs to be updated here before the skb is freed.
1156 */
1157 if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
1158 if (mp_opt.data_fin && mp_opt.data_len == 1 &&
1159 mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64))
1160 mptcp_schedule_work((struct sock *)msk);
1161
1162 return true;
1163 }
1164
1165 mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
1166 if (!mpext)
1167 return true;
1168
1169 memset(mpext, 0, sizeof(*mpext));
1170
1171 if (likely(mp_opt.use_map)) {
1172 if (mp_opt.mpc_map) {
1173 /* this is an MP_CAPABLE carrying MPTCP data
1174 * we know this map the first chunk of data
1175 */
1176 mptcp_crypto_key_sha(subflow->remote_key, NULL,
1177 &mpext->data_seq);
1178 mpext->data_seq++;
1179 mpext->subflow_seq = 1;
1180 mpext->dsn64 = 1;
1181 mpext->mpc_map = 1;
1182 mpext->data_fin = 0;
1183 } else {
1184 mpext->data_seq = mp_opt.data_seq;
1185 mpext->subflow_seq = mp_opt.subflow_seq;
1186 mpext->dsn64 = mp_opt.dsn64;
1187 mpext->data_fin = mp_opt.data_fin;
1188 }
1189 mpext->data_len = mp_opt.data_len;
1190 mpext->use_map = 1;
1191 mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD);
1192
1193 if (mpext->csum_reqd)
1194 mpext->csum = mp_opt.csum;
1195 }
1196
1197 return true;
1198 }
1199
mptcp_set_rwin(const struct tcp_sock * tp)1200 static void mptcp_set_rwin(const struct tcp_sock *tp)
1201 {
1202 const struct sock *ssk = (const struct sock *)tp;
1203 const struct mptcp_subflow_context *subflow;
1204 struct mptcp_sock *msk;
1205 u64 ack_seq;
1206
1207 subflow = mptcp_subflow_ctx(ssk);
1208 msk = mptcp_sk(subflow->conn);
1209
1210 ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
1211
1212 if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
1213 WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
1214 }
1215
__mptcp_make_csum(u64 data_seq,u32 subflow_seq,u16 data_len,__wsum sum)1216 __sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum)
1217 {
1218 struct csum_pseudo_header header;
1219 __wsum csum;
1220
1221 /* cfr RFC 8684 3.3.1.:
1222 * the data sequence number used in the pseudo-header is
1223 * always the 64-bit value, irrespective of what length is used in the
1224 * DSS option itself.
1225 */
1226 header.data_seq = cpu_to_be64(data_seq);
1227 header.subflow_seq = htonl(subflow_seq);
1228 header.data_len = htons(data_len);
1229 header.csum = 0;
1230
1231 csum = csum_partial(&header, sizeof(header), sum);
1232 return csum_fold(csum);
1233 }
1234
mptcp_make_csum(const struct mptcp_ext * mpext)1235 static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext)
1236 {
1237 return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len,
1238 ~csum_unfold(mpext->csum));
1239 }
1240
put_len_csum(u16 len,__sum16 csum,void * data)1241 static void put_len_csum(u16 len, __sum16 csum, void *data)
1242 {
1243 __sum16 *sumptr = data + 2;
1244 __be16 *ptr = data;
1245
1246 put_unaligned_be16(len, ptr);
1247
1248 put_unaligned(csum, sumptr);
1249 }
1250
mptcp_write_options(__be32 * ptr,const struct tcp_sock * tp,struct mptcp_out_options * opts)1251 void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
1252 struct mptcp_out_options *opts)
1253 {
1254 if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) {
1255 const struct sock *ssk = (const struct sock *)tp;
1256 struct mptcp_subflow_context *subflow;
1257
1258 subflow = mptcp_subflow_ctx(ssk);
1259 subflow->send_mp_fail = 0;
1260
1261 *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL,
1262 TCPOLEN_MPTCP_FAIL,
1263 0, 0);
1264 put_unaligned_be64(opts->fail_seq, ptr);
1265 ptr += 2;
1266 }
1267
1268 /* RST is mutually exclusive with everything else */
1269 if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) {
1270 *ptr++ = mptcp_option(MPTCPOPT_RST,
1271 TCPOLEN_MPTCP_RST,
1272 opts->reset_transient,
1273 opts->reset_reason);
1274 return;
1275 }
1276
1277 /* DSS, MPC, MPJ and ADD_ADDR are mutually exclusive, see
1278 * mptcp_established_options*()
1279 */
1280 if (likely(OPTION_MPTCP_DSS & opts->suboptions)) {
1281 struct mptcp_ext *mpext = &opts->ext_copy;
1282 u8 len = TCPOLEN_MPTCP_DSS_BASE;
1283 u8 flags = 0;
1284
1285 if (mpext->use_ack) {
1286 flags = MPTCP_DSS_HAS_ACK;
1287 if (mpext->ack64) {
1288 len += TCPOLEN_MPTCP_DSS_ACK64;
1289 flags |= MPTCP_DSS_ACK64;
1290 } else {
1291 len += TCPOLEN_MPTCP_DSS_ACK32;
1292 }
1293 }
1294
1295 if (mpext->use_map) {
1296 len += TCPOLEN_MPTCP_DSS_MAP64;
1297
1298 /* Use only 64-bit mapping flags for now, add
1299 * support for optional 32-bit mappings later.
1300 */
1301 flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
1302 if (mpext->data_fin)
1303 flags |= MPTCP_DSS_DATA_FIN;
1304
1305 if (opts->csum_reqd)
1306 len += TCPOLEN_MPTCP_DSS_CHECKSUM;
1307 }
1308
1309 *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
1310
1311 if (mpext->use_ack) {
1312 if (mpext->ack64) {
1313 put_unaligned_be64(mpext->data_ack, ptr);
1314 ptr += 2;
1315 } else {
1316 put_unaligned_be32(mpext->data_ack32, ptr);
1317 ptr += 1;
1318 }
1319 }
1320
1321 if (mpext->use_map) {
1322 put_unaligned_be64(mpext->data_seq, ptr);
1323 ptr += 2;
1324 put_unaligned_be32(mpext->subflow_seq, ptr);
1325 ptr += 1;
1326 if (opts->csum_reqd) {
1327 put_len_csum(mpext->data_len,
1328 mptcp_make_csum(mpext),
1329 ptr);
1330 } else {
1331 put_unaligned_be32(mpext->data_len << 16 |
1332 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1333 }
1334 ptr += 1;
1335 }
1336 } else if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
1337 OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
1338 u8 len, flag = MPTCP_CAP_HMAC_SHA256;
1339
1340 if (OPTION_MPTCP_MPC_SYN & opts->suboptions) {
1341 len = TCPOLEN_MPTCP_MPC_SYN;
1342 } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) {
1343 len = TCPOLEN_MPTCP_MPC_SYNACK;
1344 } else if (opts->data_len) {
1345 len = TCPOLEN_MPTCP_MPC_ACK_DATA;
1346 if (opts->csum_reqd)
1347 len += TCPOLEN_MPTCP_DSS_CHECKSUM;
1348 } else {
1349 len = TCPOLEN_MPTCP_MPC_ACK;
1350 }
1351
1352 if (opts->csum_reqd)
1353 flag |= MPTCP_CAP_CHECKSUM_REQD;
1354
1355 if (!opts->allow_join_id0)
1356 flag |= MPTCP_CAP_DENY_JOIN_ID0;
1357
1358 *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
1359 MPTCP_SUPPORTED_VERSION,
1360 flag);
1361
1362 if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
1363 opts->suboptions))
1364 goto mp_capable_done;
1365
1366 put_unaligned_be64(opts->sndr_key, ptr);
1367 ptr += 2;
1368 if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
1369 goto mp_capable_done;
1370
1371 put_unaligned_be64(opts->rcvr_key, ptr);
1372 ptr += 2;
1373 if (!opts->data_len)
1374 goto mp_capable_done;
1375
1376 if (opts->csum_reqd) {
1377 put_len_csum(opts->data_len,
1378 __mptcp_make_csum(opts->data_seq,
1379 opts->subflow_seq,
1380 opts->data_len,
1381 ~csum_unfold(opts->csum)),
1382 ptr);
1383 } else {
1384 put_unaligned_be32(opts->data_len << 16 |
1385 TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
1386 }
1387 ptr += 1;
1388
1389 /* MPC is additionally mutually exclusive with MP_PRIO */
1390 goto mp_capable_done;
1391 } else if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
1392 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1393 TCPOLEN_MPTCP_MPJ_SYN,
1394 opts->backup, opts->join_id);
1395 put_unaligned_be32(opts->token, ptr);
1396 ptr += 1;
1397 put_unaligned_be32(opts->nonce, ptr);
1398 ptr += 1;
1399 } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1400 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1401 TCPOLEN_MPTCP_MPJ_SYNACK,
1402 opts->backup, opts->join_id);
1403 put_unaligned_be64(opts->thmac, ptr);
1404 ptr += 2;
1405 put_unaligned_be32(opts->nonce, ptr);
1406 ptr += 1;
1407 } else if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1408 *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1409 TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1410 memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1411 ptr += 5;
1412 } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
1413 u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
1414 u8 echo = MPTCP_ADDR_ECHO;
1415
1416 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1417 if (opts->addr.family == AF_INET6)
1418 len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
1419 #endif
1420
1421 if (opts->addr.port)
1422 len += TCPOLEN_MPTCP_PORT_LEN;
1423
1424 if (opts->ahmac) {
1425 len += sizeof(opts->ahmac);
1426 echo = 0;
1427 }
1428
1429 *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
1430 len, echo, opts->addr.id);
1431 if (opts->addr.family == AF_INET) {
1432 memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4);
1433 ptr += 1;
1434 }
1435 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
1436 else if (opts->addr.family == AF_INET6) {
1437 memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16);
1438 ptr += 4;
1439 }
1440 #endif
1441
1442 if (!opts->addr.port) {
1443 if (opts->ahmac) {
1444 put_unaligned_be64(opts->ahmac, ptr);
1445 ptr += 2;
1446 }
1447 } else {
1448 u16 port = ntohs(opts->addr.port);
1449
1450 if (opts->ahmac) {
1451 u8 *bptr = (u8 *)ptr;
1452
1453 put_unaligned_be16(port, bptr);
1454 bptr += 2;
1455 put_unaligned_be64(opts->ahmac, bptr);
1456 bptr += 8;
1457 put_unaligned_be16(TCPOPT_NOP << 8 |
1458 TCPOPT_NOP, bptr);
1459
1460 ptr += 3;
1461 } else {
1462 put_unaligned_be32(port << 16 |
1463 TCPOPT_NOP << 8 |
1464 TCPOPT_NOP, ptr);
1465 ptr += 1;
1466 }
1467 }
1468 }
1469
1470 if (OPTION_MPTCP_PRIO & opts->suboptions) {
1471 const struct sock *ssk = (const struct sock *)tp;
1472 struct mptcp_subflow_context *subflow;
1473
1474 subflow = mptcp_subflow_ctx(ssk);
1475 subflow->send_mp_prio = 0;
1476
1477 *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
1478 TCPOLEN_MPTCP_PRIO,
1479 opts->backup, TCPOPT_NOP);
1480 }
1481
1482 mp_capable_done:
1483 if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
1484 u8 i = 1;
1485
1486 *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
1487 TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr,
1488 0, opts->rm_list.ids[0]);
1489
1490 while (i < opts->rm_list.nr) {
1491 u8 id1, id2, id3, id4;
1492
1493 id1 = opts->rm_list.ids[i];
1494 id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP;
1495 id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP;
1496 id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP;
1497 put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr);
1498 ptr += 1;
1499 i += 4;
1500 }
1501 }
1502
1503 if (tp)
1504 mptcp_set_rwin(tp);
1505 }
1506
mptcp_get_reset_option(const struct sk_buff * skb)1507 __be32 mptcp_get_reset_option(const struct sk_buff *skb)
1508 {
1509 const struct mptcp_ext *ext = mptcp_get_ext(skb);
1510 u8 flags, reason;
1511
1512 if (ext) {
1513 flags = ext->reset_transient;
1514 reason = ext->reset_reason;
1515
1516 return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
1517 flags, reason);
1518 }
1519
1520 return htonl(0u);
1521 }
1522 EXPORT_SYMBOL_GPL(mptcp_get_reset_option);
1523