xref: /openbmc/linux/net/mptcp/options.c (revision 06827b348b1d43850a63c3e490fe9712c124fa0c)
1eda7acddSPeter Krystad // SPDX-License-Identifier: GPL-2.0
2eda7acddSPeter Krystad /* Multipath TCP
3eda7acddSPeter Krystad  *
4eda7acddSPeter Krystad  * Copyright (c) 2017 - 2019, Intel Corporation.
5eda7acddSPeter Krystad  */
6eda7acddSPeter Krystad 
7c85adcedSGeliang Tang #define pr_fmt(fmt) "MPTCP: " fmt
8c85adcedSGeliang Tang 
9eda7acddSPeter Krystad #include <linux/kernel.h>
10bd697222STodd Malsbary #include <crypto/sha.h>
11eda7acddSPeter Krystad #include <net/tcp.h>
12eda7acddSPeter Krystad #include <net/mptcp.h>
13eda7acddSPeter Krystad #include "protocol.h"
14eda7acddSPeter Krystad 
1565492c5aSPaolo Abeni static bool mptcp_cap_flag_sha256(u8 flags)
1665492c5aSPaolo Abeni {
1765492c5aSPaolo Abeni 	return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
1865492c5aSPaolo Abeni }
1965492c5aSPaolo Abeni 
20cfde141eSPaolo Abeni static void mptcp_parse_option(const struct sk_buff *skb,
21cfde141eSPaolo Abeni 			       const unsigned char *ptr, int opsize,
22cfde141eSPaolo Abeni 			       struct mptcp_options_received *mp_opt)
23eda7acddSPeter Krystad {
24eda7acddSPeter Krystad 	u8 subtype = *ptr >> 4;
25648ef4b8SMat Martineau 	int expected_opsize;
26eda7acddSPeter Krystad 	u8 version;
27eda7acddSPeter Krystad 	u8 flags;
28eda7acddSPeter Krystad 
29eda7acddSPeter Krystad 	switch (subtype) {
30eda7acddSPeter Krystad 	case MPTCPOPT_MP_CAPABLE:
31cc7972eaSChristoph Paasch 		/* strict size checking */
32cc7972eaSChristoph Paasch 		if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
33cc7972eaSChristoph Paasch 			if (skb->len > tcp_hdr(skb)->doff << 2)
34cc7972eaSChristoph Paasch 				expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
35cc7972eaSChristoph Paasch 			else
36cc7972eaSChristoph Paasch 				expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
37cc7972eaSChristoph Paasch 		} else {
38cc7972eaSChristoph Paasch 			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
39cc7972eaSChristoph Paasch 				expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
40cc7972eaSChristoph Paasch 			else
41cc7972eaSChristoph Paasch 				expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
42cc7972eaSChristoph Paasch 		}
43cc7972eaSChristoph Paasch 		if (opsize != expected_opsize)
44eda7acddSPeter Krystad 			break;
45eda7acddSPeter Krystad 
46cc7972eaSChristoph Paasch 		/* try to be gentle vs future versions on the initial syn */
47eda7acddSPeter Krystad 		version = *ptr++ & MPTCP_VERSION_MASK;
48cc7972eaSChristoph Paasch 		if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
49eda7acddSPeter Krystad 			if (version != MPTCP_SUPPORTED_VERSION)
50eda7acddSPeter Krystad 				break;
51cc7972eaSChristoph Paasch 		} else if (version < MPTCP_SUPPORTED_VERSION) {
52cc7972eaSChristoph Paasch 			break;
53cc7972eaSChristoph Paasch 		}
54eda7acddSPeter Krystad 
55eda7acddSPeter Krystad 		flags = *ptr++;
5665492c5aSPaolo Abeni 		if (!mptcp_cap_flag_sha256(flags) ||
57eda7acddSPeter Krystad 		    (flags & MPTCP_CAP_EXTENSIBILITY))
58eda7acddSPeter Krystad 			break;
59eda7acddSPeter Krystad 
60eda7acddSPeter Krystad 		/* RFC 6824, Section 3.1:
61eda7acddSPeter Krystad 		 * "For the Checksum Required bit (labeled "A"), if either
62eda7acddSPeter Krystad 		 * host requires the use of checksums, checksums MUST be used.
63eda7acddSPeter Krystad 		 * In other words, the only way for checksums not to be used
64eda7acddSPeter Krystad 		 * is if both hosts in their SYNs set A=0."
65eda7acddSPeter Krystad 		 *
66eda7acddSPeter Krystad 		 * Section 3.3.0:
67eda7acddSPeter Krystad 		 * "If a checksum is not present when its use has been
68eda7acddSPeter Krystad 		 * negotiated, the receiver MUST close the subflow with a RST as
69eda7acddSPeter Krystad 		 * it is considered broken."
70eda7acddSPeter Krystad 		 *
71eda7acddSPeter Krystad 		 * We don't implement DSS checksum - fall back to TCP.
72eda7acddSPeter Krystad 		 */
73eda7acddSPeter Krystad 		if (flags & MPTCP_CAP_CHECKSUM_REQD)
74eda7acddSPeter Krystad 			break;
75eda7acddSPeter Krystad 
76eda7acddSPeter Krystad 		mp_opt->mp_capable = 1;
77cc7972eaSChristoph Paasch 		if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
78eda7acddSPeter Krystad 			mp_opt->sndr_key = get_unaligned_be64(ptr);
79eda7acddSPeter Krystad 			ptr += 8;
80cc7972eaSChristoph Paasch 		}
81cc7972eaSChristoph Paasch 		if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
82eda7acddSPeter Krystad 			mp_opt->rcvr_key = get_unaligned_be64(ptr);
83eda7acddSPeter Krystad 			ptr += 8;
84eda7acddSPeter Krystad 		}
85cc7972eaSChristoph Paasch 		if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA) {
86cc7972eaSChristoph Paasch 			/* Section 3.1.:
87cc7972eaSChristoph Paasch 			 * "the data parameters in a MP_CAPABLE are semantically
88cc7972eaSChristoph Paasch 			 * equivalent to those in a DSS option and can be used
89cc7972eaSChristoph Paasch 			 * interchangeably."
90cc7972eaSChristoph Paasch 			 */
91cc7972eaSChristoph Paasch 			mp_opt->dss = 1;
92cc7972eaSChristoph Paasch 			mp_opt->use_map = 1;
93cc7972eaSChristoph Paasch 			mp_opt->mpc_map = 1;
94cc7972eaSChristoph Paasch 			mp_opt->data_len = get_unaligned_be16(ptr);
95cc7972eaSChristoph Paasch 			ptr += 2;
96cc7972eaSChristoph Paasch 		}
97cc7972eaSChristoph Paasch 		pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
98cc7972eaSChristoph Paasch 			 version, flags, opsize, mp_opt->sndr_key,
99cc7972eaSChristoph Paasch 			 mp_opt->rcvr_key, mp_opt->data_len);
100eda7acddSPeter Krystad 		break;
101eda7acddSPeter Krystad 
102f296234cSPeter Krystad 	case MPTCPOPT_MP_JOIN:
103f296234cSPeter Krystad 		mp_opt->mp_join = 1;
104f296234cSPeter Krystad 		if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
105f296234cSPeter Krystad 			mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
106f296234cSPeter Krystad 			mp_opt->join_id = *ptr++;
107f296234cSPeter Krystad 			mp_opt->token = get_unaligned_be32(ptr);
108f296234cSPeter Krystad 			ptr += 4;
109f296234cSPeter Krystad 			mp_opt->nonce = get_unaligned_be32(ptr);
110f296234cSPeter Krystad 			ptr += 4;
111f296234cSPeter Krystad 			pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
112f296234cSPeter Krystad 				 mp_opt->backup, mp_opt->join_id,
113f296234cSPeter Krystad 				 mp_opt->token, mp_opt->nonce);
114f296234cSPeter Krystad 		} else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
115f296234cSPeter Krystad 			mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
116f296234cSPeter Krystad 			mp_opt->join_id = *ptr++;
117f296234cSPeter Krystad 			mp_opt->thmac = get_unaligned_be64(ptr);
118f296234cSPeter Krystad 			ptr += 8;
119f296234cSPeter Krystad 			mp_opt->nonce = get_unaligned_be32(ptr);
120f296234cSPeter Krystad 			ptr += 4;
121f296234cSPeter Krystad 			pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
122f296234cSPeter Krystad 				 mp_opt->backup, mp_opt->join_id,
123f296234cSPeter Krystad 				 mp_opt->thmac, mp_opt->nonce);
124f296234cSPeter Krystad 		} else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
125f296234cSPeter Krystad 			ptr += 2;
126f296234cSPeter Krystad 			memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
127f296234cSPeter Krystad 			pr_debug("MP_JOIN hmac");
128f296234cSPeter Krystad 		} else {
129f296234cSPeter Krystad 			pr_warn("MP_JOIN bad option size");
130f296234cSPeter Krystad 			mp_opt->mp_join = 0;
131f296234cSPeter Krystad 		}
132f296234cSPeter Krystad 		break;
133f296234cSPeter Krystad 
134eda7acddSPeter Krystad 	case MPTCPOPT_DSS:
135eda7acddSPeter Krystad 		pr_debug("DSS");
136648ef4b8SMat Martineau 		ptr++;
137648ef4b8SMat Martineau 
138cc7972eaSChristoph Paasch 		/* we must clear 'mpc_map' be able to detect MP_CAPABLE
139cc7972eaSChristoph Paasch 		 * map vs DSS map in mptcp_incoming_options(), and reconstruct
140cc7972eaSChristoph Paasch 		 * map info accordingly
141cc7972eaSChristoph Paasch 		 */
142cc7972eaSChristoph Paasch 		mp_opt->mpc_map = 0;
143648ef4b8SMat Martineau 		flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
144648ef4b8SMat Martineau 		mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
145648ef4b8SMat Martineau 		mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
146648ef4b8SMat Martineau 		mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
147648ef4b8SMat Martineau 		mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
148648ef4b8SMat Martineau 		mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
149648ef4b8SMat Martineau 
150648ef4b8SMat Martineau 		pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
151648ef4b8SMat Martineau 			 mp_opt->data_fin, mp_opt->dsn64,
152648ef4b8SMat Martineau 			 mp_opt->use_map, mp_opt->ack64,
153648ef4b8SMat Martineau 			 mp_opt->use_ack);
154648ef4b8SMat Martineau 
155648ef4b8SMat Martineau 		expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
156648ef4b8SMat Martineau 
157648ef4b8SMat Martineau 		if (mp_opt->use_ack) {
158648ef4b8SMat Martineau 			if (mp_opt->ack64)
159648ef4b8SMat Martineau 				expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
160648ef4b8SMat Martineau 			else
161648ef4b8SMat Martineau 				expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
162648ef4b8SMat Martineau 		}
163648ef4b8SMat Martineau 
164648ef4b8SMat Martineau 		if (mp_opt->use_map) {
165648ef4b8SMat Martineau 			if (mp_opt->dsn64)
166648ef4b8SMat Martineau 				expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
167648ef4b8SMat Martineau 			else
168648ef4b8SMat Martineau 				expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
169648ef4b8SMat Martineau 		}
170648ef4b8SMat Martineau 
171648ef4b8SMat Martineau 		/* RFC 6824, Section 3.3:
172648ef4b8SMat Martineau 		 * If a checksum is present, but its use had
173648ef4b8SMat Martineau 		 * not been negotiated in the MP_CAPABLE handshake,
174648ef4b8SMat Martineau 		 * the checksum field MUST be ignored.
175648ef4b8SMat Martineau 		 */
176648ef4b8SMat Martineau 		if (opsize != expected_opsize &&
177648ef4b8SMat Martineau 		    opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
178648ef4b8SMat Martineau 			break;
179648ef4b8SMat Martineau 
180eda7acddSPeter Krystad 		mp_opt->dss = 1;
181648ef4b8SMat Martineau 
182648ef4b8SMat Martineau 		if (mp_opt->use_ack) {
183648ef4b8SMat Martineau 			if (mp_opt->ack64) {
184648ef4b8SMat Martineau 				mp_opt->data_ack = get_unaligned_be64(ptr);
185648ef4b8SMat Martineau 				ptr += 8;
186648ef4b8SMat Martineau 			} else {
187648ef4b8SMat Martineau 				mp_opt->data_ack = get_unaligned_be32(ptr);
188648ef4b8SMat Martineau 				ptr += 4;
189648ef4b8SMat Martineau 			}
190648ef4b8SMat Martineau 
191648ef4b8SMat Martineau 			pr_debug("data_ack=%llu", mp_opt->data_ack);
192648ef4b8SMat Martineau 		}
193648ef4b8SMat Martineau 
194648ef4b8SMat Martineau 		if (mp_opt->use_map) {
195648ef4b8SMat Martineau 			if (mp_opt->dsn64) {
196648ef4b8SMat Martineau 				mp_opt->data_seq = get_unaligned_be64(ptr);
197648ef4b8SMat Martineau 				ptr += 8;
198648ef4b8SMat Martineau 			} else {
199648ef4b8SMat Martineau 				mp_opt->data_seq = get_unaligned_be32(ptr);
200648ef4b8SMat Martineau 				ptr += 4;
201648ef4b8SMat Martineau 			}
202648ef4b8SMat Martineau 
203648ef4b8SMat Martineau 			mp_opt->subflow_seq = get_unaligned_be32(ptr);
204648ef4b8SMat Martineau 			ptr += 4;
205648ef4b8SMat Martineau 
206648ef4b8SMat Martineau 			mp_opt->data_len = get_unaligned_be16(ptr);
207648ef4b8SMat Martineau 			ptr += 2;
208648ef4b8SMat Martineau 
209648ef4b8SMat Martineau 			pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
210648ef4b8SMat Martineau 				 mp_opt->data_seq, mp_opt->subflow_seq,
211648ef4b8SMat Martineau 				 mp_opt->data_len);
212648ef4b8SMat Martineau 		}
213648ef4b8SMat Martineau 
214eda7acddSPeter Krystad 		break;
215eda7acddSPeter Krystad 
2163df523abSPeter Krystad 	case MPTCPOPT_ADD_ADDR:
2173df523abSPeter Krystad 		mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
2183df523abSPeter Krystad 		if (!mp_opt->echo) {
2193df523abSPeter Krystad 			if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
2203df523abSPeter Krystad 			    opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
2213df523abSPeter Krystad 				mp_opt->family = MPTCP_ADDR_IPVERSION_4;
2223df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2233df523abSPeter Krystad 			else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
2243df523abSPeter Krystad 				 opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
2253df523abSPeter Krystad 				mp_opt->family = MPTCP_ADDR_IPVERSION_6;
2263df523abSPeter Krystad #endif
2273df523abSPeter Krystad 			else
2283df523abSPeter Krystad 				break;
2293df523abSPeter Krystad 		} else {
2303df523abSPeter Krystad 			if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
2313df523abSPeter Krystad 			    opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
2323df523abSPeter Krystad 				mp_opt->family = MPTCP_ADDR_IPVERSION_4;
2333df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2343df523abSPeter Krystad 			else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
2353df523abSPeter Krystad 				 opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
2363df523abSPeter Krystad 				mp_opt->family = MPTCP_ADDR_IPVERSION_6;
2373df523abSPeter Krystad #endif
2383df523abSPeter Krystad 			else
2393df523abSPeter Krystad 				break;
2403df523abSPeter Krystad 		}
2413df523abSPeter Krystad 
2423df523abSPeter Krystad 		mp_opt->add_addr = 1;
2433df523abSPeter Krystad 		mp_opt->port = 0;
2443df523abSPeter Krystad 		mp_opt->addr_id = *ptr++;
2453df523abSPeter Krystad 		pr_debug("ADD_ADDR: id=%d", mp_opt->addr_id);
2463df523abSPeter Krystad 		if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
2473df523abSPeter Krystad 			memcpy((u8 *)&mp_opt->addr.s_addr, (u8 *)ptr, 4);
2483df523abSPeter Krystad 			ptr += 4;
2493df523abSPeter Krystad 			if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
2503df523abSPeter Krystad 			    opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
2513df523abSPeter Krystad 				mp_opt->port = get_unaligned_be16(ptr);
2523df523abSPeter Krystad 				ptr += 2;
2533df523abSPeter Krystad 			}
2543df523abSPeter Krystad 		}
2553df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
2563df523abSPeter Krystad 		else {
2573df523abSPeter Krystad 			memcpy(mp_opt->addr6.s6_addr, (u8 *)ptr, 16);
2583df523abSPeter Krystad 			ptr += 16;
2593df523abSPeter Krystad 			if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
2603df523abSPeter Krystad 			    opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
2613df523abSPeter Krystad 				mp_opt->port = get_unaligned_be16(ptr);
2623df523abSPeter Krystad 				ptr += 2;
2633df523abSPeter Krystad 			}
2643df523abSPeter Krystad 		}
2653df523abSPeter Krystad #endif
2663df523abSPeter Krystad 		if (!mp_opt->echo) {
2673df523abSPeter Krystad 			mp_opt->ahmac = get_unaligned_be64(ptr);
2683df523abSPeter Krystad 			ptr += 8;
2693df523abSPeter Krystad 		}
2703df523abSPeter Krystad 		break;
2713df523abSPeter Krystad 
2723df523abSPeter Krystad 	case MPTCPOPT_RM_ADDR:
2733df523abSPeter Krystad 		if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
2743df523abSPeter Krystad 			break;
2753df523abSPeter Krystad 
2768e60eed6SGeliang Tang 		ptr++;
2778e60eed6SGeliang Tang 
2783df523abSPeter Krystad 		mp_opt->rm_addr = 1;
2793df523abSPeter Krystad 		mp_opt->rm_id = *ptr++;
2803df523abSPeter Krystad 		pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);
2813df523abSPeter Krystad 		break;
2823df523abSPeter Krystad 
283eda7acddSPeter Krystad 	default:
284eda7acddSPeter Krystad 		break;
285eda7acddSPeter Krystad 	}
286eda7acddSPeter Krystad }
287eda7acddSPeter Krystad 
288cec37a6eSPeter Krystad void mptcp_get_options(const struct sk_buff *skb,
289cfde141eSPaolo Abeni 		       struct mptcp_options_received *mp_opt)
290cec37a6eSPeter Krystad {
291cec37a6eSPeter Krystad 	const struct tcphdr *th = tcp_hdr(skb);
292cfde141eSPaolo Abeni 	const unsigned char *ptr;
293cfde141eSPaolo Abeni 	int length;
294cec37a6eSPeter Krystad 
295cfde141eSPaolo Abeni 	/* initialize option status */
296cfde141eSPaolo Abeni 	mp_opt->mp_capable = 0;
297cfde141eSPaolo Abeni 	mp_opt->mp_join = 0;
298cfde141eSPaolo Abeni 	mp_opt->add_addr = 0;
299cfde141eSPaolo Abeni 	mp_opt->rm_addr = 0;
300cfde141eSPaolo Abeni 	mp_opt->dss = 0;
301cfde141eSPaolo Abeni 
302cfde141eSPaolo Abeni 	length = (th->doff * 4) - sizeof(struct tcphdr);
303cec37a6eSPeter Krystad 	ptr = (const unsigned char *)(th + 1);
304cec37a6eSPeter Krystad 
305cec37a6eSPeter Krystad 	while (length > 0) {
306cec37a6eSPeter Krystad 		int opcode = *ptr++;
307cec37a6eSPeter Krystad 		int opsize;
308cec37a6eSPeter Krystad 
309cec37a6eSPeter Krystad 		switch (opcode) {
310cec37a6eSPeter Krystad 		case TCPOPT_EOL:
311cec37a6eSPeter Krystad 			return;
312cec37a6eSPeter Krystad 		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
313cec37a6eSPeter Krystad 			length--;
314cec37a6eSPeter Krystad 			continue;
315cec37a6eSPeter Krystad 		default:
316cec37a6eSPeter Krystad 			opsize = *ptr++;
317cec37a6eSPeter Krystad 			if (opsize < 2) /* "silly options" */
318cec37a6eSPeter Krystad 				return;
319cec37a6eSPeter Krystad 			if (opsize > length)
320cec37a6eSPeter Krystad 				return;	/* don't parse partial options */
321cec37a6eSPeter Krystad 			if (opcode == TCPOPT_MPTCP)
322cfde141eSPaolo Abeni 				mptcp_parse_option(skb, ptr, opsize, mp_opt);
323cec37a6eSPeter Krystad 			ptr += opsize - 2;
324cec37a6eSPeter Krystad 			length -= opsize;
325cec37a6eSPeter Krystad 		}
326cec37a6eSPeter Krystad 	}
327cec37a6eSPeter Krystad }
328cec37a6eSPeter Krystad 
329cc7972eaSChristoph Paasch bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
330cc7972eaSChristoph Paasch 		       unsigned int *size, struct mptcp_out_options *opts)
331cec37a6eSPeter Krystad {
332cec37a6eSPeter Krystad 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
333cec37a6eSPeter Krystad 
334cc7972eaSChristoph Paasch 	/* we will use snd_isn to detect first pkt [re]transmission
335cc7972eaSChristoph Paasch 	 * in mptcp_established_options_mp()
336cc7972eaSChristoph Paasch 	 */
337cc7972eaSChristoph Paasch 	subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
338cec37a6eSPeter Krystad 	if (subflow->request_mptcp) {
339cec37a6eSPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPC_SYN;
340cec37a6eSPeter Krystad 		*size = TCPOLEN_MPTCP_MPC_SYN;
341cec37a6eSPeter Krystad 		return true;
342ec3edaa7SPeter Krystad 	} else if (subflow->request_join) {
343ec3edaa7SPeter Krystad 		pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
344ec3edaa7SPeter Krystad 			 subflow->local_nonce);
345ec3edaa7SPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPJ_SYN;
346ec3edaa7SPeter Krystad 		opts->join_id = subflow->local_id;
347ec3edaa7SPeter Krystad 		opts->token = subflow->remote_token;
348ec3edaa7SPeter Krystad 		opts->nonce = subflow->local_nonce;
349ec3edaa7SPeter Krystad 		opts->backup = subflow->request_bkup;
350ec3edaa7SPeter Krystad 		*size = TCPOLEN_MPTCP_MPJ_SYN;
351ec3edaa7SPeter Krystad 		return true;
352cec37a6eSPeter Krystad 	}
353cec37a6eSPeter Krystad 	return false;
354cec37a6eSPeter Krystad }
355cec37a6eSPeter Krystad 
356ec3edaa7SPeter Krystad /* MP_JOIN client subflow must wait for 4th ack before sending any data:
357ec3edaa7SPeter Krystad  * TCP can't schedule delack timer before the subflow is fully established.
358ec3edaa7SPeter Krystad  * MPTCP uses the delack timer to do 3rd ack retransmissions
359ec3edaa7SPeter Krystad  */
360ec3edaa7SPeter Krystad static void schedule_3rdack_retransmission(struct sock *sk)
361ec3edaa7SPeter Krystad {
362ec3edaa7SPeter Krystad 	struct inet_connection_sock *icsk = inet_csk(sk);
363ec3edaa7SPeter Krystad 	struct tcp_sock *tp = tcp_sk(sk);
364ec3edaa7SPeter Krystad 	unsigned long timeout;
365ec3edaa7SPeter Krystad 
366ec3edaa7SPeter Krystad 	/* reschedule with a timeout above RTT, as we must look only for drop */
367ec3edaa7SPeter Krystad 	if (tp->srtt_us)
368ec3edaa7SPeter Krystad 		timeout = tp->srtt_us << 1;
369ec3edaa7SPeter Krystad 	else
370ec3edaa7SPeter Krystad 		timeout = TCP_TIMEOUT_INIT;
371ec3edaa7SPeter Krystad 
372ec3edaa7SPeter Krystad 	WARN_ON_ONCE(icsk->icsk_ack.pending & ICSK_ACK_TIMER);
373ec3edaa7SPeter Krystad 	icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
374ec3edaa7SPeter Krystad 	icsk->icsk_ack.timeout = timeout;
375ec3edaa7SPeter Krystad 	sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
376ec3edaa7SPeter Krystad }
377ec3edaa7SPeter Krystad 
378ec3edaa7SPeter Krystad static void clear_3rdack_retransmission(struct sock *sk)
379ec3edaa7SPeter Krystad {
380ec3edaa7SPeter Krystad 	struct inet_connection_sock *icsk = inet_csk(sk);
381ec3edaa7SPeter Krystad 
382ec3edaa7SPeter Krystad 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
383ec3edaa7SPeter Krystad 	icsk->icsk_ack.timeout = 0;
384ec3edaa7SPeter Krystad 	icsk->icsk_ack.ato = 0;
385ec3edaa7SPeter Krystad 	icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
386ec3edaa7SPeter Krystad }
387ec3edaa7SPeter Krystad 
388cc7972eaSChristoph Paasch static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
389cc7972eaSChristoph Paasch 					 unsigned int *size,
3906d0060f6SMat Martineau 					 unsigned int remaining,
391cec37a6eSPeter Krystad 					 struct mptcp_out_options *opts)
392cec37a6eSPeter Krystad {
393cec37a6eSPeter Krystad 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
394cc7972eaSChristoph Paasch 	struct mptcp_ext *mpext;
395cc7972eaSChristoph Paasch 	unsigned int data_len;
396cec37a6eSPeter Krystad 
397ec3edaa7SPeter Krystad 	/* When skb is not available, we better over-estimate the emitted
398ec3edaa7SPeter Krystad 	 * options len. A full DSS option (28 bytes) is longer than
399ec3edaa7SPeter Krystad 	 * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
400ec3edaa7SPeter Krystad 	 * tell the caller to defer the estimate to
401ec3edaa7SPeter Krystad 	 * mptcp_established_options_dss(), which will reserve enough space.
402cc7972eaSChristoph Paasch 	 */
403ec3edaa7SPeter Krystad 	if (!skb)
404ec3edaa7SPeter Krystad 		return false;
405ec3edaa7SPeter Krystad 
406ec3edaa7SPeter Krystad 	/* MPC/MPJ needed only on 3rd ack packet */
407ec3edaa7SPeter Krystad 	if (subflow->fully_established ||
408ec3edaa7SPeter Krystad 	    subflow->snd_isn != TCP_SKB_CB(skb)->seq)
409ec3edaa7SPeter Krystad 		return false;
410ec3edaa7SPeter Krystad 
411ec3edaa7SPeter Krystad 	if (subflow->mp_capable) {
412cc7972eaSChristoph Paasch 		mpext = mptcp_get_ext(skb);
413cc7972eaSChristoph Paasch 		data_len = mpext ? mpext->data_len : 0;
414cc7972eaSChristoph Paasch 
415cc7972eaSChristoph Paasch 		/* we will check ext_copy.data_len in mptcp_write_options() to
416cc7972eaSChristoph Paasch 		 * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
417cc7972eaSChristoph Paasch 		 * TCPOLEN_MPTCP_MPC_ACK
418cc7972eaSChristoph Paasch 		 */
419cc7972eaSChristoph Paasch 		opts->ext_copy.data_len = data_len;
420cec37a6eSPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPC_ACK;
421cec37a6eSPeter Krystad 		opts->sndr_key = subflow->local_key;
422cec37a6eSPeter Krystad 		opts->rcvr_key = subflow->remote_key;
423cc7972eaSChristoph Paasch 
424cc7972eaSChristoph Paasch 		/* Section 3.1.
425cc7972eaSChristoph Paasch 		 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
426cc7972eaSChristoph Paasch 		 * packets that start the first subflow of an MPTCP connection,
427cc7972eaSChristoph Paasch 		 * as well as the first packet that carries data
428cc7972eaSChristoph Paasch 		 */
429cc7972eaSChristoph Paasch 		if (data_len > 0)
430cc7972eaSChristoph Paasch 			*size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
431cc7972eaSChristoph Paasch 		else
432cec37a6eSPeter Krystad 			*size = TCPOLEN_MPTCP_MPC_ACK;
433cc7972eaSChristoph Paasch 
434cc7972eaSChristoph Paasch 		pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
435cc7972eaSChristoph Paasch 			 subflow, subflow->local_key, subflow->remote_key,
436cc7972eaSChristoph Paasch 			 data_len);
437cc7972eaSChristoph Paasch 
438cec37a6eSPeter Krystad 		return true;
439ec3edaa7SPeter Krystad 	} else if (subflow->mp_join) {
440ec3edaa7SPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPJ_ACK;
441ec3edaa7SPeter Krystad 		memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
442ec3edaa7SPeter Krystad 		*size = TCPOLEN_MPTCP_MPJ_ACK;
443ec3edaa7SPeter Krystad 		pr_debug("subflow=%p", subflow);
444ec3edaa7SPeter Krystad 
445ec3edaa7SPeter Krystad 		schedule_3rdack_retransmission(sk);
446ec3edaa7SPeter Krystad 		return true;
447cec37a6eSPeter Krystad 	}
448cec37a6eSPeter Krystad 	return false;
449cec37a6eSPeter Krystad }
450cec37a6eSPeter Krystad 
4516d0060f6SMat Martineau static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
4529c29e361SPaolo Abeni 				 struct sk_buff *skb, struct mptcp_ext *ext)
4536d0060f6SMat Martineau {
4547279da61SMat Martineau 	u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq);
4557279da61SMat Martineau 
4569c29e361SPaolo Abeni 	if (!ext->use_map || !skb->len) {
4576d0060f6SMat Martineau 		/* RFC6824 requires a DSS mapping with specific values
4586d0060f6SMat Martineau 		 * if DATA_FIN is set but no data payload is mapped
4596d0060f6SMat Martineau 		 */
4606d37a0b8SMat Martineau 		ext->data_fin = 1;
4616d0060f6SMat Martineau 		ext->use_map = 1;
4626d0060f6SMat Martineau 		ext->dsn64 = 1;
4637279da61SMat Martineau 		/* The write_seq value has already been incremented, so
4647279da61SMat Martineau 		 * the actual sequence number for the DATA_FIN is one less.
4657279da61SMat Martineau 		 */
4667279da61SMat Martineau 		ext->data_seq = data_fin_tx_seq - 1;
4676d0060f6SMat Martineau 		ext->subflow_seq = 0;
4686d0060f6SMat Martineau 		ext->data_len = 1;
4697279da61SMat Martineau 	} else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
4706d37a0b8SMat Martineau 		/* If there's an existing DSS mapping and it is the
4716d37a0b8SMat Martineau 		 * final mapping, DATA_FIN consumes 1 additional byte of
4726d37a0b8SMat Martineau 		 * mapping space.
4736d0060f6SMat Martineau 		 */
4746d37a0b8SMat Martineau 		ext->data_fin = 1;
4756d0060f6SMat Martineau 		ext->data_len++;
4766d0060f6SMat Martineau 	}
4776d0060f6SMat Martineau }
4786d0060f6SMat Martineau 
4796d0060f6SMat Martineau static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
4806d0060f6SMat Martineau 					  unsigned int *size,
4816d0060f6SMat Martineau 					  unsigned int remaining,
4826d0060f6SMat Martineau 					  struct mptcp_out_options *opts)
4836d0060f6SMat Martineau {
4846d0060f6SMat Martineau 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
4857279da61SMat Martineau 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
4866d0060f6SMat Martineau 	unsigned int dss_size = 0;
4877279da61SMat Martineau 	u64 snd_data_fin_enable;
4886d0060f6SMat Martineau 	struct mptcp_ext *mpext;
4896d0060f6SMat Martineau 	unsigned int ack_size;
490d22f4988SChristoph Paasch 	bool ret = false;
4916d0060f6SMat Martineau 
4920bac966aSMat Martineau 	mpext = skb ? mptcp_get_ext(skb) : NULL;
4937279da61SMat Martineau 	snd_data_fin_enable = READ_ONCE(msk->snd_data_fin_enable);
4946d0060f6SMat Martineau 
4957279da61SMat Martineau 	if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
4966d0060f6SMat Martineau 		unsigned int map_size;
4976d0060f6SMat Martineau 
4986d0060f6SMat Martineau 		map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
4996d0060f6SMat Martineau 
5006d0060f6SMat Martineau 		remaining -= map_size;
5016d0060f6SMat Martineau 		dss_size = map_size;
5026d0060f6SMat Martineau 		if (mpext)
5036d0060f6SMat Martineau 			opts->ext_copy = *mpext;
5046d0060f6SMat Martineau 
5057279da61SMat Martineau 		if (skb && snd_data_fin_enable)
5069c29e361SPaolo Abeni 			mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
507d22f4988SChristoph Paasch 		ret = true;
508d22f4988SChristoph Paasch 	}
509d22f4988SChristoph Paasch 
5102398e399SPaolo Abeni 	/* passive sockets msk will set the 'can_ack' after accept(), even
5112398e399SPaolo Abeni 	 * if the first subflow may have the already the remote key handy
5122398e399SPaolo Abeni 	 */
513d22f4988SChristoph Paasch 	opts->ext_copy.use_ack = 0;
514dc093db5SPaolo Abeni 	if (!READ_ONCE(msk->can_ack)) {
515d22f4988SChristoph Paasch 		*size = ALIGN(dss_size, 4);
516d22f4988SChristoph Paasch 		return ret;
5176d0060f6SMat Martineau 	}
5186d0060f6SMat Martineau 
519a0c1d0eaSChristoph Paasch 	if (subflow->use_64bit_ack) {
5206d0060f6SMat Martineau 		ack_size = TCPOLEN_MPTCP_DSS_ACK64;
521a0c1d0eaSChristoph Paasch 		opts->ext_copy.data_ack = msk->ack_seq;
522a0c1d0eaSChristoph Paasch 		opts->ext_copy.ack64 = 1;
523a0c1d0eaSChristoph Paasch 	} else {
524a0c1d0eaSChristoph Paasch 		ack_size = TCPOLEN_MPTCP_DSS_ACK32;
525a0c1d0eaSChristoph Paasch 		opts->ext_copy.data_ack32 = (uint32_t)(msk->ack_seq);
526a0c1d0eaSChristoph Paasch 		opts->ext_copy.ack64 = 0;
527a0c1d0eaSChristoph Paasch 	}
528a0c1d0eaSChristoph Paasch 	opts->ext_copy.use_ack = 1;
5296d0060f6SMat Martineau 
5306d0060f6SMat Martineau 	/* Add kind/length/subtype/flag overhead if mapping is not populated */
5316d0060f6SMat Martineau 	if (dss_size == 0)
5326d0060f6SMat Martineau 		ack_size += TCPOLEN_MPTCP_DSS_BASE;
5336d0060f6SMat Martineau 
5346d0060f6SMat Martineau 	dss_size += ack_size;
5356d0060f6SMat Martineau 
5366d0060f6SMat Martineau 	*size = ALIGN(dss_size, 4);
5376d0060f6SMat Martineau 	return true;
5386d0060f6SMat Martineau }
5396d0060f6SMat Martineau 
5403df523abSPeter Krystad static u64 add_addr_generate_hmac(u64 key1, u64 key2, u8 addr_id,
5413df523abSPeter Krystad 				  struct in_addr *addr)
5423df523abSPeter Krystad {
543bd697222STodd Malsbary 	u8 hmac[SHA256_DIGEST_SIZE];
5443df523abSPeter Krystad 	u8 msg[7];
5453df523abSPeter Krystad 
5463df523abSPeter Krystad 	msg[0] = addr_id;
5473df523abSPeter Krystad 	memcpy(&msg[1], &addr->s_addr, 4);
5483df523abSPeter Krystad 	msg[5] = 0;
5493df523abSPeter Krystad 	msg[6] = 0;
5503df523abSPeter Krystad 
5513df523abSPeter Krystad 	mptcp_crypto_hmac_sha(key1, key2, msg, 7, hmac);
5523df523abSPeter Krystad 
553bd697222STodd Malsbary 	return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
5543df523abSPeter Krystad }
5553df523abSPeter Krystad 
5563df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
5573df523abSPeter Krystad static u64 add_addr6_generate_hmac(u64 key1, u64 key2, u8 addr_id,
5583df523abSPeter Krystad 				   struct in6_addr *addr)
5593df523abSPeter Krystad {
560bd697222STodd Malsbary 	u8 hmac[SHA256_DIGEST_SIZE];
5613df523abSPeter Krystad 	u8 msg[19];
5623df523abSPeter Krystad 
5633df523abSPeter Krystad 	msg[0] = addr_id;
5643df523abSPeter Krystad 	memcpy(&msg[1], &addr->s6_addr, 16);
5653df523abSPeter Krystad 	msg[17] = 0;
5663df523abSPeter Krystad 	msg[18] = 0;
5673df523abSPeter Krystad 
5683df523abSPeter Krystad 	mptcp_crypto_hmac_sha(key1, key2, msg, 19, hmac);
5693df523abSPeter Krystad 
570bd697222STodd Malsbary 	return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
5713df523abSPeter Krystad }
5723df523abSPeter Krystad #endif
5733df523abSPeter Krystad 
5743df523abSPeter Krystad static bool mptcp_established_options_addr(struct sock *sk,
5753df523abSPeter Krystad 					   unsigned int *size,
5763df523abSPeter Krystad 					   unsigned int remaining,
5773df523abSPeter Krystad 					   struct mptcp_out_options *opts)
5783df523abSPeter Krystad {
5793df523abSPeter Krystad 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
5803df523abSPeter Krystad 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
5811b1c7a0eSPeter Krystad 	struct mptcp_addr_info saddr;
5821b1c7a0eSPeter Krystad 	int len;
5833df523abSPeter Krystad 
5841b1c7a0eSPeter Krystad 	if (!mptcp_pm_should_signal(msk) ||
5851b1c7a0eSPeter Krystad 	    !(mptcp_pm_addr_signal(msk, remaining, &saddr)))
5863df523abSPeter Krystad 		return false;
5871b1c7a0eSPeter Krystad 
5881b1c7a0eSPeter Krystad 	len = mptcp_add_addr_len(saddr.family);
5891b1c7a0eSPeter Krystad 	if (remaining < len)
5901b1c7a0eSPeter Krystad 		return false;
5911b1c7a0eSPeter Krystad 
5921b1c7a0eSPeter Krystad 	*size = len;
5931b1c7a0eSPeter Krystad 	opts->addr_id = saddr.id;
5941b1c7a0eSPeter Krystad 	if (saddr.family == AF_INET) {
5953df523abSPeter Krystad 		opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
5961b1c7a0eSPeter Krystad 		opts->addr = saddr.addr;
5973df523abSPeter Krystad 		opts->ahmac = add_addr_generate_hmac(msk->local_key,
5983df523abSPeter Krystad 						     msk->remote_key,
5993df523abSPeter Krystad 						     opts->addr_id,
6003df523abSPeter Krystad 						     &opts->addr);
6013df523abSPeter Krystad 	}
6023df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
6031b1c7a0eSPeter Krystad 	else if (saddr.family == AF_INET6) {
6043df523abSPeter Krystad 		opts->suboptions |= OPTION_MPTCP_ADD_ADDR6;
6051b1c7a0eSPeter Krystad 		opts->addr6 = saddr.addr6;
6063df523abSPeter Krystad 		opts->ahmac = add_addr6_generate_hmac(msk->local_key,
6073df523abSPeter Krystad 						      msk->remote_key,
6083df523abSPeter Krystad 						      opts->addr_id,
6093df523abSPeter Krystad 						      &opts->addr6);
6103df523abSPeter Krystad 	}
6113df523abSPeter Krystad #endif
6123df523abSPeter Krystad 	pr_debug("addr_id=%d, ahmac=%llu", opts->addr_id, opts->ahmac);
6133df523abSPeter Krystad 
6143df523abSPeter Krystad 	return true;
6153df523abSPeter Krystad }
6163df523abSPeter Krystad 
6176d0060f6SMat Martineau bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
6186d0060f6SMat Martineau 			       unsigned int *size, unsigned int remaining,
6196d0060f6SMat Martineau 			       struct mptcp_out_options *opts)
6206d0060f6SMat Martineau {
6216d0060f6SMat Martineau 	unsigned int opt_size = 0;
6226d0060f6SMat Martineau 	bool ret = false;
6236d0060f6SMat Martineau 
6243df523abSPeter Krystad 	opts->suboptions = 0;
6253df523abSPeter Krystad 
626e1ff9e82SDavide Caratti 	if (unlikely(mptcp_check_fallback(sk)))
627e1ff9e82SDavide Caratti 		return false;
628e1ff9e82SDavide Caratti 
629cc7972eaSChristoph Paasch 	if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
6306d0060f6SMat Martineau 		ret = true;
6316d0060f6SMat Martineau 	else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
6326d0060f6SMat Martineau 					       opts))
6336d0060f6SMat Martineau 		ret = true;
6346d0060f6SMat Martineau 
6356d0060f6SMat Martineau 	/* we reserved enough space for the above options, and exceeding the
6366d0060f6SMat Martineau 	 * TCP option space would be fatal
6376d0060f6SMat Martineau 	 */
6386d0060f6SMat Martineau 	if (WARN_ON_ONCE(opt_size > remaining))
6396d0060f6SMat Martineau 		return false;
6406d0060f6SMat Martineau 
6416d0060f6SMat Martineau 	*size += opt_size;
6426d0060f6SMat Martineau 	remaining -= opt_size;
6433df523abSPeter Krystad 	if (mptcp_established_options_addr(sk, &opt_size, remaining, opts)) {
6443df523abSPeter Krystad 		*size += opt_size;
6453df523abSPeter Krystad 		remaining -= opt_size;
6463df523abSPeter Krystad 		ret = true;
6473df523abSPeter Krystad 	}
6486d0060f6SMat Martineau 
6496d0060f6SMat Martineau 	return ret;
6506d0060f6SMat Martineau }
6516d0060f6SMat Martineau 
652cec37a6eSPeter Krystad bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
653cec37a6eSPeter Krystad 			  struct mptcp_out_options *opts)
654cec37a6eSPeter Krystad {
655cec37a6eSPeter Krystad 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
656cec37a6eSPeter Krystad 
657cec37a6eSPeter Krystad 	if (subflow_req->mp_capable) {
658cec37a6eSPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
659cec37a6eSPeter Krystad 		opts->sndr_key = subflow_req->local_key;
660cec37a6eSPeter Krystad 		*size = TCPOLEN_MPTCP_MPC_SYNACK;
661cec37a6eSPeter Krystad 		pr_debug("subflow_req=%p, local_key=%llu",
662cec37a6eSPeter Krystad 			 subflow_req, subflow_req->local_key);
663cec37a6eSPeter Krystad 		return true;
664f296234cSPeter Krystad 	} else if (subflow_req->mp_join) {
665f296234cSPeter Krystad 		opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
666f296234cSPeter Krystad 		opts->backup = subflow_req->backup;
667f296234cSPeter Krystad 		opts->join_id = subflow_req->local_id;
668f296234cSPeter Krystad 		opts->thmac = subflow_req->thmac;
669f296234cSPeter Krystad 		opts->nonce = subflow_req->local_nonce;
670f296234cSPeter Krystad 		pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
671f296234cSPeter Krystad 			 subflow_req, opts->backup, opts->join_id,
672f296234cSPeter Krystad 			 opts->thmac, opts->nonce);
673f296234cSPeter Krystad 		*size = TCPOLEN_MPTCP_MPJ_SYNACK;
674f296234cSPeter Krystad 		return true;
675cec37a6eSPeter Krystad 	}
676cec37a6eSPeter Krystad 	return false;
677cec37a6eSPeter Krystad }
678cec37a6eSPeter Krystad 
679f296234cSPeter Krystad static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk,
680f296234cSPeter Krystad 				    struct mptcp_subflow_context *subflow,
681d22f4988SChristoph Paasch 				    struct sk_buff *skb,
682d22f4988SChristoph Paasch 				    struct mptcp_options_received *mp_opt)
683d22f4988SChristoph Paasch {
684d22f4988SChristoph Paasch 	/* here we can process OoO, in-window pkts, only in-sequence 4th ack
685f296234cSPeter Krystad 	 * will make the subflow fully established
686d22f4988SChristoph Paasch 	 */
687f296234cSPeter Krystad 	if (likely(subflow->fully_established)) {
688f296234cSPeter Krystad 		/* on passive sockets, check for 3rd ack retransmission
689f296234cSPeter Krystad 		 * note that msk is always set by subflow_syn_recv_sock()
690f296234cSPeter Krystad 		 * for mp_join subflows
691f296234cSPeter Krystad 		 */
692f296234cSPeter Krystad 		if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
693f296234cSPeter Krystad 		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
694f296234cSPeter Krystad 		    subflow->mp_join && mp_opt->mp_join &&
695f296234cSPeter Krystad 		    READ_ONCE(msk->pm.server_side))
696f296234cSPeter Krystad 			tcp_send_ack(sk);
697f296234cSPeter Krystad 		goto fully_established;
698f296234cSPeter Krystad 	}
699d22f4988SChristoph Paasch 
700f296234cSPeter Krystad 	/* we should process OoO packets before the first subflow is fully
701f296234cSPeter Krystad 	 * established, but not expected for MP_JOIN subflows
702f296234cSPeter Krystad 	 */
703f296234cSPeter Krystad 	if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1)
704f296234cSPeter Krystad 		return subflow->mp_capable;
705f296234cSPeter Krystad 
7065a91e32bSPaolo Abeni 	if (mp_opt->dss && mp_opt->use_ack) {
707f296234cSPeter Krystad 		/* subflows are fully established as soon as we get any
708f296234cSPeter Krystad 		 * additional ack.
709f296234cSPeter Krystad 		 */
7100be534f5SPaolo Abeni 		subflow->fully_established = 1;
711b93df08cSPaolo Abeni 		WRITE_ONCE(msk->fully_established, true);
712f296234cSPeter Krystad 		goto fully_established;
713f296234cSPeter Krystad 	}
714d22f4988SChristoph Paasch 
715d22f4988SChristoph Paasch 	/* If the first established packet does not contain MP_CAPABLE + data
716d22f4988SChristoph Paasch 	 * then fallback to TCP
717d22f4988SChristoph Paasch 	 */
718d22f4988SChristoph Paasch 	if (!mp_opt->mp_capable) {
719d22f4988SChristoph Paasch 		subflow->mp_capable = 0;
720e1ff9e82SDavide Caratti 		pr_fallback(msk);
721e1ff9e82SDavide Caratti 		__mptcp_do_fallback(msk);
722d22f4988SChristoph Paasch 		return false;
723d22f4988SChristoph Paasch 	}
724f296234cSPeter Krystad 
725d6085fe1SPaolo Abeni 	if (unlikely(!READ_ONCE(msk->pm.server_side)))
726d6085fe1SPaolo Abeni 		pr_warn_once("bogus mpc option on established client sk");
727b93df08cSPaolo Abeni 	mptcp_subflow_fully_established(subflow, mp_opt);
728f296234cSPeter Krystad 
729f296234cSPeter Krystad fully_established:
730f296234cSPeter Krystad 	if (likely(subflow->pm_notified))
731f296234cSPeter Krystad 		return true;
732f296234cSPeter Krystad 
733f296234cSPeter Krystad 	subflow->pm_notified = 1;
734ec3edaa7SPeter Krystad 	if (subflow->mp_join) {
735ec3edaa7SPeter Krystad 		clear_3rdack_retransmission(sk);
736f296234cSPeter Krystad 		mptcp_pm_subflow_established(msk, subflow);
737ec3edaa7SPeter Krystad 	} else {
738f296234cSPeter Krystad 		mptcp_pm_fully_established(msk);
739ec3edaa7SPeter Krystad 	}
740d22f4988SChristoph Paasch 	return true;
741d22f4988SChristoph Paasch }
742d22f4988SChristoph Paasch 
743cc9d2566SPaolo Abeni static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
744cc9d2566SPaolo Abeni {
745cc9d2566SPaolo Abeni 	u32 old_ack32, cur_ack32;
746cc9d2566SPaolo Abeni 
747cc9d2566SPaolo Abeni 	if (use_64bit)
748cc9d2566SPaolo Abeni 		return cur_ack;
749cc9d2566SPaolo Abeni 
750cc9d2566SPaolo Abeni 	old_ack32 = (u32)old_ack;
751cc9d2566SPaolo Abeni 	cur_ack32 = (u32)cur_ack;
752cc9d2566SPaolo Abeni 	cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
753cc9d2566SPaolo Abeni 	if (unlikely(before(cur_ack32, old_ack32)))
754cc9d2566SPaolo Abeni 		return cur_ack + (1LL << 32);
755cc9d2566SPaolo Abeni 	return cur_ack;
756cc9d2566SPaolo Abeni }
757cc9d2566SPaolo Abeni 
758cc9d2566SPaolo Abeni static void update_una(struct mptcp_sock *msk,
759cc9d2566SPaolo Abeni 		       struct mptcp_options_received *mp_opt)
760cc9d2566SPaolo Abeni {
761cc9d2566SPaolo Abeni 	u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
762cc9d2566SPaolo Abeni 	u64 write_seq = READ_ONCE(msk->write_seq);
763cc9d2566SPaolo Abeni 
764cc9d2566SPaolo Abeni 	/* avoid ack expansion on update conflict, to reduce the risk of
765cc9d2566SPaolo Abeni 	 * wrongly expanding to a future ack sequence number, which is way
766cc9d2566SPaolo Abeni 	 * more dangerous than missing an ack
767cc9d2566SPaolo Abeni 	 */
768cc9d2566SPaolo Abeni 	new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
769cc9d2566SPaolo Abeni 
770cc9d2566SPaolo Abeni 	/* ACK for data not even sent yet? Ignore. */
771cc9d2566SPaolo Abeni 	if (after64(new_snd_una, write_seq))
772cc9d2566SPaolo Abeni 		new_snd_una = old_snd_una;
773cc9d2566SPaolo Abeni 
774cc9d2566SPaolo Abeni 	while (after64(new_snd_una, old_snd_una)) {
775cc9d2566SPaolo Abeni 		snd_una = old_snd_una;
776cc9d2566SPaolo Abeni 		old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
777cc9d2566SPaolo Abeni 					       new_snd_una);
778b51f9b80SPaolo Abeni 		if (old_snd_una == snd_una) {
779b51f9b80SPaolo Abeni 			mptcp_data_acked((struct sock *)msk);
780cc9d2566SPaolo Abeni 			break;
781cc9d2566SPaolo Abeni 		}
782cc9d2566SPaolo Abeni 	}
783b51f9b80SPaolo Abeni }
784cc9d2566SPaolo Abeni 
7853721b9b6SMat Martineau bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq)
7863721b9b6SMat Martineau {
7873721b9b6SMat Martineau 	/* Skip if DATA_FIN was already received.
7883721b9b6SMat Martineau 	 * If updating simultaneously with the recvmsg loop, values
7893721b9b6SMat Martineau 	 * should match. If they mismatch, the peer is misbehaving and
7903721b9b6SMat Martineau 	 * we will prefer the most recent information.
7913721b9b6SMat Martineau 	 */
7923721b9b6SMat Martineau 	if (READ_ONCE(msk->rcv_data_fin) || !READ_ONCE(msk->first))
7933721b9b6SMat Martineau 		return false;
7943721b9b6SMat Martineau 
7953721b9b6SMat Martineau 	WRITE_ONCE(msk->rcv_data_fin_seq, data_fin_seq);
7963721b9b6SMat Martineau 	WRITE_ONCE(msk->rcv_data_fin, 1);
7973721b9b6SMat Martineau 
7983721b9b6SMat Martineau 	return true;
7993721b9b6SMat Martineau }
8003721b9b6SMat Martineau 
8011b1c7a0eSPeter Krystad static bool add_addr_hmac_valid(struct mptcp_sock *msk,
8021b1c7a0eSPeter Krystad 				struct mptcp_options_received *mp_opt)
8031b1c7a0eSPeter Krystad {
8041b1c7a0eSPeter Krystad 	u64 hmac = 0;
8051b1c7a0eSPeter Krystad 
8061b1c7a0eSPeter Krystad 	if (mp_opt->echo)
8071b1c7a0eSPeter Krystad 		return true;
8081b1c7a0eSPeter Krystad 
8091b1c7a0eSPeter Krystad 	if (mp_opt->family == MPTCP_ADDR_IPVERSION_4)
8101b1c7a0eSPeter Krystad 		hmac = add_addr_generate_hmac(msk->remote_key,
8111b1c7a0eSPeter Krystad 					      msk->local_key,
8121b1c7a0eSPeter Krystad 					      mp_opt->addr_id, &mp_opt->addr);
8131b1c7a0eSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
8141b1c7a0eSPeter Krystad 	else
8151b1c7a0eSPeter Krystad 		hmac = add_addr6_generate_hmac(msk->remote_key,
8161b1c7a0eSPeter Krystad 					       msk->local_key,
8171b1c7a0eSPeter Krystad 					       mp_opt->addr_id, &mp_opt->addr6);
8181b1c7a0eSPeter Krystad #endif
8191b1c7a0eSPeter Krystad 
8201b1c7a0eSPeter Krystad 	pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
8211b1c7a0eSPeter Krystad 		 msk, (unsigned long long)hmac,
8221b1c7a0eSPeter Krystad 		 (unsigned long long)mp_opt->ahmac);
8231b1c7a0eSPeter Krystad 
8241b1c7a0eSPeter Krystad 	return hmac == mp_opt->ahmac;
8251b1c7a0eSPeter Krystad }
8261b1c7a0eSPeter Krystad 
827648ef4b8SMat Martineau void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
828648ef4b8SMat Martineau 			    struct tcp_options_received *opt_rx)
829648ef4b8SMat Martineau {
830d22f4988SChristoph Paasch 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
8311b1c7a0eSPeter Krystad 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
832cfde141eSPaolo Abeni 	struct mptcp_options_received mp_opt;
833648ef4b8SMat Martineau 	struct mptcp_ext *mpext;
834648ef4b8SMat Martineau 
835e1ff9e82SDavide Caratti 	if (__mptcp_check_fallback(msk))
836e1ff9e82SDavide Caratti 		return;
837e1ff9e82SDavide Caratti 
838cfde141eSPaolo Abeni 	mptcp_get_options(skb, &mp_opt);
839cfde141eSPaolo Abeni 	if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
840d22f4988SChristoph Paasch 		return;
841648ef4b8SMat Martineau 
842cfde141eSPaolo Abeni 	if (mp_opt.add_addr && add_addr_hmac_valid(msk, &mp_opt)) {
8431b1c7a0eSPeter Krystad 		struct mptcp_addr_info addr;
8441b1c7a0eSPeter Krystad 
845cfde141eSPaolo Abeni 		addr.port = htons(mp_opt.port);
846cfde141eSPaolo Abeni 		addr.id = mp_opt.addr_id;
847cfde141eSPaolo Abeni 		if (mp_opt.family == MPTCP_ADDR_IPVERSION_4) {
8481b1c7a0eSPeter Krystad 			addr.family = AF_INET;
849cfde141eSPaolo Abeni 			addr.addr = mp_opt.addr;
8501b1c7a0eSPeter Krystad 		}
8511b1c7a0eSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
852cfde141eSPaolo Abeni 		else if (mp_opt.family == MPTCP_ADDR_IPVERSION_6) {
8531b1c7a0eSPeter Krystad 			addr.family = AF_INET6;
854cfde141eSPaolo Abeni 			addr.addr6 = mp_opt.addr6;
8551b1c7a0eSPeter Krystad 		}
8561b1c7a0eSPeter Krystad #endif
857cfde141eSPaolo Abeni 		if (!mp_opt.echo)
8581b1c7a0eSPeter Krystad 			mptcp_pm_add_addr_received(msk, &addr);
859cfde141eSPaolo Abeni 		mp_opt.add_addr = 0;
8601b1c7a0eSPeter Krystad 	}
8611b1c7a0eSPeter Krystad 
862cfde141eSPaolo Abeni 	if (!mp_opt.dss)
863648ef4b8SMat Martineau 		return;
864648ef4b8SMat Martineau 
865cc9d2566SPaolo Abeni 	/* we can't wait for recvmsg() to update the ack_seq, otherwise
866cc9d2566SPaolo Abeni 	 * monodirectional flows will stuck
867cc9d2566SPaolo Abeni 	 */
868cfde141eSPaolo Abeni 	if (mp_opt.use_ack)
869cfde141eSPaolo Abeni 		update_una(msk, &mp_opt);
870cc9d2566SPaolo Abeni 
871*06827b34SMat Martineau 	/* Zero-data-length packets are dropped by the caller and not
872*06827b34SMat Martineau 	 * propagated to the MPTCP layer, so the skb extension does not
873*06827b34SMat Martineau 	 * need to be allocated or populated. DATA_FIN information, if
874*06827b34SMat Martineau 	 * present, needs to be updated here before the skb is freed.
87543b54c6eSMat Martineau 	 */
87643b54c6eSMat Martineau 	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
87743b54c6eSMat Martineau 		if (mp_opt.data_fin && mp_opt.data_len == 1 &&
87843b54c6eSMat Martineau 		    mptcp_update_rcv_data_fin(msk, mp_opt.data_seq) &&
87943b54c6eSMat Martineau 		    schedule_work(&msk->work))
88043b54c6eSMat Martineau 			sock_hold(subflow->conn);
881*06827b34SMat Martineau 
882*06827b34SMat Martineau 		return;
88343b54c6eSMat Martineau 	}
88443b54c6eSMat Martineau 
885648ef4b8SMat Martineau 	mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
886648ef4b8SMat Martineau 	if (!mpext)
887648ef4b8SMat Martineau 		return;
888648ef4b8SMat Martineau 
889648ef4b8SMat Martineau 	memset(mpext, 0, sizeof(*mpext));
890648ef4b8SMat Martineau 
891cfde141eSPaolo Abeni 	if (mp_opt.use_map) {
892cfde141eSPaolo Abeni 		if (mp_opt.mpc_map) {
893cc7972eaSChristoph Paasch 			/* this is an MP_CAPABLE carrying MPTCP data
894cc7972eaSChristoph Paasch 			 * we know this map the first chunk of data
895cc7972eaSChristoph Paasch 			 */
896cc7972eaSChristoph Paasch 			mptcp_crypto_key_sha(subflow->remote_key, NULL,
897cc7972eaSChristoph Paasch 					     &mpext->data_seq);
898cc7972eaSChristoph Paasch 			mpext->data_seq++;
899cc7972eaSChristoph Paasch 			mpext->subflow_seq = 1;
900cc7972eaSChristoph Paasch 			mpext->dsn64 = 1;
901cc7972eaSChristoph Paasch 			mpext->mpc_map = 1;
902a77895dbSPaolo Abeni 			mpext->data_fin = 0;
903cc7972eaSChristoph Paasch 		} else {
904cfde141eSPaolo Abeni 			mpext->data_seq = mp_opt.data_seq;
905cfde141eSPaolo Abeni 			mpext->subflow_seq = mp_opt.subflow_seq;
906cfde141eSPaolo Abeni 			mpext->dsn64 = mp_opt.dsn64;
907cfde141eSPaolo Abeni 			mpext->data_fin = mp_opt.data_fin;
908cc7972eaSChristoph Paasch 		}
909cfde141eSPaolo Abeni 		mpext->data_len = mp_opt.data_len;
910648ef4b8SMat Martineau 		mpext->use_map = 1;
911648ef4b8SMat Martineau 	}
912648ef4b8SMat Martineau }
913648ef4b8SMat Martineau 
914eda7acddSPeter Krystad void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
915eda7acddSPeter Krystad {
916cc7972eaSChristoph Paasch 	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
917eda7acddSPeter Krystad 	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
918eda7acddSPeter Krystad 		u8 len;
919eda7acddSPeter Krystad 
920eda7acddSPeter Krystad 		if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
921eda7acddSPeter Krystad 			len = TCPOLEN_MPTCP_MPC_SYN;
922cec37a6eSPeter Krystad 		else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
923cec37a6eSPeter Krystad 			len = TCPOLEN_MPTCP_MPC_SYNACK;
924cc7972eaSChristoph Paasch 		else if (opts->ext_copy.data_len)
925cc7972eaSChristoph Paasch 			len = TCPOLEN_MPTCP_MPC_ACK_DATA;
926eda7acddSPeter Krystad 		else
927eda7acddSPeter Krystad 			len = TCPOLEN_MPTCP_MPC_ACK;
928eda7acddSPeter Krystad 
9293df523abSPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
9303df523abSPeter Krystad 				      MPTCP_SUPPORTED_VERSION,
93165492c5aSPaolo Abeni 				      MPTCP_CAP_HMAC_SHA256);
932cc7972eaSChristoph Paasch 
933cc7972eaSChristoph Paasch 		if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
934cc7972eaSChristoph Paasch 		    opts->suboptions))
935cc7972eaSChristoph Paasch 			goto mp_capable_done;
936cc7972eaSChristoph Paasch 
937eda7acddSPeter Krystad 		put_unaligned_be64(opts->sndr_key, ptr);
938eda7acddSPeter Krystad 		ptr += 2;
939cc7972eaSChristoph Paasch 		if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
940cc7972eaSChristoph Paasch 			goto mp_capable_done;
941cc7972eaSChristoph Paasch 
942eda7acddSPeter Krystad 		put_unaligned_be64(opts->rcvr_key, ptr);
943eda7acddSPeter Krystad 		ptr += 2;
944cc7972eaSChristoph Paasch 		if (!opts->ext_copy.data_len)
945cc7972eaSChristoph Paasch 			goto mp_capable_done;
946cc7972eaSChristoph Paasch 
947cc7972eaSChristoph Paasch 		put_unaligned_be32(opts->ext_copy.data_len << 16 |
948cc7972eaSChristoph Paasch 				   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
949cc7972eaSChristoph Paasch 		ptr += 1;
950eda7acddSPeter Krystad 	}
9516d0060f6SMat Martineau 
952cc7972eaSChristoph Paasch mp_capable_done:
9533df523abSPeter Krystad 	if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
9543df523abSPeter Krystad 		if (opts->ahmac)
9553df523abSPeter Krystad 			*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
9563df523abSPeter Krystad 					      TCPOLEN_MPTCP_ADD_ADDR, 0,
9573df523abSPeter Krystad 					      opts->addr_id);
9583df523abSPeter Krystad 		else
9593df523abSPeter Krystad 			*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
9603df523abSPeter Krystad 					      TCPOLEN_MPTCP_ADD_ADDR_BASE,
9613df523abSPeter Krystad 					      MPTCP_ADDR_ECHO,
9623df523abSPeter Krystad 					      opts->addr_id);
9633df523abSPeter Krystad 		memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
9643df523abSPeter Krystad 		ptr += 1;
9653df523abSPeter Krystad 		if (opts->ahmac) {
9663df523abSPeter Krystad 			put_unaligned_be64(opts->ahmac, ptr);
9673df523abSPeter Krystad 			ptr += 2;
9683df523abSPeter Krystad 		}
9693df523abSPeter Krystad 	}
9703df523abSPeter Krystad 
9713df523abSPeter Krystad #if IS_ENABLED(CONFIG_MPTCP_IPV6)
9723df523abSPeter Krystad 	if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
9733df523abSPeter Krystad 		if (opts->ahmac)
9743df523abSPeter Krystad 			*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
9753df523abSPeter Krystad 					      TCPOLEN_MPTCP_ADD_ADDR6, 0,
9763df523abSPeter Krystad 					      opts->addr_id);
9773df523abSPeter Krystad 		else
9783df523abSPeter Krystad 			*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
9793df523abSPeter Krystad 					      TCPOLEN_MPTCP_ADD_ADDR6_BASE,
9803df523abSPeter Krystad 					      MPTCP_ADDR_ECHO,
9813df523abSPeter Krystad 					      opts->addr_id);
9823df523abSPeter Krystad 		memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
9833df523abSPeter Krystad 		ptr += 4;
9843df523abSPeter Krystad 		if (opts->ahmac) {
9853df523abSPeter Krystad 			put_unaligned_be64(opts->ahmac, ptr);
9863df523abSPeter Krystad 			ptr += 2;
9873df523abSPeter Krystad 		}
9883df523abSPeter Krystad 	}
9893df523abSPeter Krystad #endif
9903df523abSPeter Krystad 
9913df523abSPeter Krystad 	if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
9923df523abSPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
9933df523abSPeter Krystad 				      TCPOLEN_MPTCP_RM_ADDR_BASE,
9943df523abSPeter Krystad 				      0, opts->rm_id);
9953df523abSPeter Krystad 	}
9963df523abSPeter Krystad 
997ec3edaa7SPeter Krystad 	if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
998ec3edaa7SPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
999ec3edaa7SPeter Krystad 				      TCPOLEN_MPTCP_MPJ_SYN,
1000ec3edaa7SPeter Krystad 				      opts->backup, opts->join_id);
1001ec3edaa7SPeter Krystad 		put_unaligned_be32(opts->token, ptr);
1002ec3edaa7SPeter Krystad 		ptr += 1;
1003ec3edaa7SPeter Krystad 		put_unaligned_be32(opts->nonce, ptr);
1004ec3edaa7SPeter Krystad 		ptr += 1;
1005ec3edaa7SPeter Krystad 	}
1006ec3edaa7SPeter Krystad 
1007f296234cSPeter Krystad 	if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
1008f296234cSPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1009f296234cSPeter Krystad 				      TCPOLEN_MPTCP_MPJ_SYNACK,
1010f296234cSPeter Krystad 				      opts->backup, opts->join_id);
1011f296234cSPeter Krystad 		put_unaligned_be64(opts->thmac, ptr);
1012f296234cSPeter Krystad 		ptr += 2;
1013f296234cSPeter Krystad 		put_unaligned_be32(opts->nonce, ptr);
1014f296234cSPeter Krystad 		ptr += 1;
1015f296234cSPeter Krystad 	}
1016f296234cSPeter Krystad 
1017ec3edaa7SPeter Krystad 	if (OPTION_MPTCP_MPJ_ACK & opts->suboptions) {
1018ec3edaa7SPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
1019ec3edaa7SPeter Krystad 				      TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
1020ec3edaa7SPeter Krystad 		memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
1021ec3edaa7SPeter Krystad 		ptr += 5;
1022ec3edaa7SPeter Krystad 	}
1023ec3edaa7SPeter Krystad 
10246d0060f6SMat Martineau 	if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
10256d0060f6SMat Martineau 		struct mptcp_ext *mpext = &opts->ext_copy;
10266d0060f6SMat Martineau 		u8 len = TCPOLEN_MPTCP_DSS_BASE;
10276d0060f6SMat Martineau 		u8 flags = 0;
10286d0060f6SMat Martineau 
10296d0060f6SMat Martineau 		if (mpext->use_ack) {
1030a0c1d0eaSChristoph Paasch 			flags = MPTCP_DSS_HAS_ACK;
1031a0c1d0eaSChristoph Paasch 			if (mpext->ack64) {
10326d0060f6SMat Martineau 				len += TCPOLEN_MPTCP_DSS_ACK64;
1033a0c1d0eaSChristoph Paasch 				flags |= MPTCP_DSS_ACK64;
1034a0c1d0eaSChristoph Paasch 			} else {
1035a0c1d0eaSChristoph Paasch 				len += TCPOLEN_MPTCP_DSS_ACK32;
1036a0c1d0eaSChristoph Paasch 			}
10376d0060f6SMat Martineau 		}
10386d0060f6SMat Martineau 
10396d0060f6SMat Martineau 		if (mpext->use_map) {
10406d0060f6SMat Martineau 			len += TCPOLEN_MPTCP_DSS_MAP64;
10416d0060f6SMat Martineau 
10426d0060f6SMat Martineau 			/* Use only 64-bit mapping flags for now, add
10436d0060f6SMat Martineau 			 * support for optional 32-bit mappings later.
10446d0060f6SMat Martineau 			 */
10456d0060f6SMat Martineau 			flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
10466d0060f6SMat Martineau 			if (mpext->data_fin)
10476d0060f6SMat Martineau 				flags |= MPTCP_DSS_DATA_FIN;
10486d0060f6SMat Martineau 		}
10496d0060f6SMat Martineau 
10503df523abSPeter Krystad 		*ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
10516d0060f6SMat Martineau 
10526d0060f6SMat Martineau 		if (mpext->use_ack) {
1053a0c1d0eaSChristoph Paasch 			if (mpext->ack64) {
10546d0060f6SMat Martineau 				put_unaligned_be64(mpext->data_ack, ptr);
10556d0060f6SMat Martineau 				ptr += 2;
1056a0c1d0eaSChristoph Paasch 			} else {
1057a0c1d0eaSChristoph Paasch 				put_unaligned_be32(mpext->data_ack32, ptr);
1058a0c1d0eaSChristoph Paasch 				ptr += 1;
1059a0c1d0eaSChristoph Paasch 			}
10606d0060f6SMat Martineau 		}
10616d0060f6SMat Martineau 
10626d0060f6SMat Martineau 		if (mpext->use_map) {
10636d0060f6SMat Martineau 			put_unaligned_be64(mpext->data_seq, ptr);
10646d0060f6SMat Martineau 			ptr += 2;
10656d0060f6SMat Martineau 			put_unaligned_be32(mpext->subflow_seq, ptr);
10666d0060f6SMat Martineau 			ptr += 1;
10676d0060f6SMat Martineau 			put_unaligned_be32(mpext->data_len << 16 |
10686d0060f6SMat Martineau 					   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
10696d0060f6SMat Martineau 		}
10706d0060f6SMat Martineau 	}
1071eda7acddSPeter Krystad }
1072