diff options
Diffstat (limited to 'net/mptcp/options.c')
| -rw-r--r-- | net/mptcp/options.c | 1653 |
1 files changed, 1653 insertions, 0 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c new file mode 100644 index 0000000000..d2527d189a --- /dev/null +++ b/net/mptcp/options.c @@ -0,0 +1,1653 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Multipath TCP + * + * Copyright (c) 2017 - 2019, Intel Corporation. + */ + +#define pr_fmt(fmt) "MPTCP: " fmt + +#include <linux/kernel.h> +#include <crypto/sha2.h> +#include <net/tcp.h> +#include <net/mptcp.h> +#include "protocol.h" +#include "mib.h" + +#include <trace/events/mptcp.h> + +static bool mptcp_cap_flag_sha256(u8 flags) +{ + return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256; +} + +static void mptcp_parse_option(const struct sk_buff *skb, + const unsigned char *ptr, int opsize, + struct mptcp_options_received *mp_opt) +{ + u8 subtype = *ptr >> 4; + int expected_opsize; + u16 subopt; + u8 version; + u8 flags; + u8 i; + + switch (subtype) { + case MPTCPOPT_MP_CAPABLE: + /* strict size checking */ + if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { + if (skb->len > tcp_hdr(skb)->doff << 2) + expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA; + else + expected_opsize = TCPOLEN_MPTCP_MPC_ACK; + subopt = OPTION_MPTCP_MPC_ACK; + } else { + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK) { + expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK; + subopt = OPTION_MPTCP_MPC_SYNACK; + } else { + expected_opsize = TCPOLEN_MPTCP_MPC_SYN; + subopt = OPTION_MPTCP_MPC_SYN; + } + } + + /* Cfr RFC 8684 Section 3.3.0: + * If a checksum is present but its use had + * not been negotiated in the MP_CAPABLE handshake, the receiver MUST + * close the subflow with a RST, as it is not behaving as negotiated. + * If a checksum is not present when its use has been negotiated, the + * receiver MUST close the subflow with a RST, as it is considered + * broken + * We parse even option with mismatching csum presence, so that + * later in subflow_data_ready we can trigger the reset. + */ + if (opsize != expected_opsize && + (expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA || + opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM)) + break; + + /* try to be gentle vs future versions on the initial syn */ + version = *ptr++ & MPTCP_VERSION_MASK; + if (opsize != TCPOLEN_MPTCP_MPC_SYN) { + if (version != MPTCP_SUPPORTED_VERSION) + break; + } else if (version < MPTCP_SUPPORTED_VERSION) { + break; + } + + flags = *ptr++; + if (!mptcp_cap_flag_sha256(flags) || + (flags & MPTCP_CAP_EXTENSIBILITY)) + break; + + /* RFC 6824, Section 3.1: + * "For the Checksum Required bit (labeled "A"), if either + * host requires the use of checksums, checksums MUST be used. + * In other words, the only way for checksums not to be used + * is if both hosts in their SYNs set A=0." + */ + if (flags & MPTCP_CAP_CHECKSUM_REQD) + mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; + + mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0); + + mp_opt->suboptions |= subopt; + if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) { + mp_opt->sndr_key = get_unaligned_be64(ptr); + ptr += 8; + } + if (opsize >= TCPOLEN_MPTCP_MPC_ACK) { + mp_opt->rcvr_key = get_unaligned_be64(ptr); + ptr += 8; + } + if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) { + /* Section 3.1.: + * "the data parameters in a MP_CAPABLE are semantically + * equivalent to those in a DSS option and can be used + * interchangeably." + */ + mp_opt->suboptions |= OPTION_MPTCP_DSS; + mp_opt->use_map = 1; + mp_opt->mpc_map = 1; + mp_opt->use_ack = 0; + mp_opt->data_len = get_unaligned_be16(ptr); + ptr += 2; + } + if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) { + mp_opt->csum = get_unaligned((__force __sum16 *)ptr); + mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; + ptr += 2; + } + pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u", + version, flags, opsize, mp_opt->sndr_key, + mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum); + break; + + case MPTCPOPT_MP_JOIN: + if (opsize == TCPOLEN_MPTCP_MPJ_SYN) { + mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYN; + mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; + mp_opt->join_id = *ptr++; + mp_opt->token = get_unaligned_be32(ptr); + ptr += 4; + mp_opt->nonce = get_unaligned_be32(ptr); + ptr += 4; + pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u", + mp_opt->backup, mp_opt->join_id, + mp_opt->token, mp_opt->nonce); + } else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) { + mp_opt->suboptions |= OPTION_MPTCP_MPJ_SYNACK; + mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP; + mp_opt->join_id = *ptr++; + mp_opt->thmac = get_unaligned_be64(ptr); + ptr += 8; + mp_opt->nonce = get_unaligned_be32(ptr); + ptr += 4; + pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u", + mp_opt->backup, mp_opt->join_id, + mp_opt->thmac, mp_opt->nonce); + } else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) { + mp_opt->suboptions |= OPTION_MPTCP_MPJ_ACK; + ptr += 2; + memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN); + pr_debug("MP_JOIN hmac"); + } + break; + + case MPTCPOPT_DSS: + pr_debug("DSS"); + ptr++; + + /* we must clear 'mpc_map' be able to detect MP_CAPABLE + * map vs DSS map in mptcp_incoming_options(), and reconstruct + * map info accordingly + */ + mp_opt->mpc_map = 0; + flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; + mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; + mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; + mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0; + mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0; + mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK); + + pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d", + mp_opt->data_fin, mp_opt->dsn64, + mp_opt->use_map, mp_opt->ack64, + mp_opt->use_ack); + + expected_opsize = TCPOLEN_MPTCP_DSS_BASE; + + if (mp_opt->use_ack) { + if (mp_opt->ack64) + expected_opsize += TCPOLEN_MPTCP_DSS_ACK64; + else + expected_opsize += TCPOLEN_MPTCP_DSS_ACK32; + } + + if (mp_opt->use_map) { + if (mp_opt->dsn64) + expected_opsize += TCPOLEN_MPTCP_DSS_MAP64; + else + expected_opsize += TCPOLEN_MPTCP_DSS_MAP32; + } + + /* Always parse any csum presence combination, we will enforce + * RFC 8684 Section 3.3.0 checks later in subflow_data_ready + */ + if (opsize != expected_opsize && + opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) + break; + + mp_opt->suboptions |= OPTION_MPTCP_DSS; + if (mp_opt->use_ack) { + if (mp_opt->ack64) { + mp_opt->data_ack = get_unaligned_be64(ptr); + ptr += 8; + } else { + mp_opt->data_ack = get_unaligned_be32(ptr); + ptr += 4; + } + + pr_debug("data_ack=%llu", mp_opt->data_ack); + } + + if (mp_opt->use_map) { + if (mp_opt->dsn64) { + mp_opt->data_seq = get_unaligned_be64(ptr); + ptr += 8; + } else { + mp_opt->data_seq = get_unaligned_be32(ptr); + ptr += 4; + } + + mp_opt->subflow_seq = get_unaligned_be32(ptr); + ptr += 4; + + mp_opt->data_len = get_unaligned_be16(ptr); + ptr += 2; + + if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) { + mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD; + mp_opt->csum = get_unaligned((__force __sum16 *)ptr); + ptr += 2; + } + + pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u", + mp_opt->data_seq, mp_opt->subflow_seq, + mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD), + mp_opt->csum); + } + + break; + + case MPTCPOPT_ADD_ADDR: + mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO; + if (!mp_opt->echo) { + if (opsize == TCPOLEN_MPTCP_ADD_ADDR || + opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT) + mp_opt->addr.family = AF_INET; +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 || + opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT) + mp_opt->addr.family = AF_INET6; +#endif + else + break; + } else { + if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE || + opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) + mp_opt->addr.family = AF_INET; +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE || + opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) + mp_opt->addr.family = AF_INET6; +#endif + else + break; + } + + mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR; + mp_opt->addr.id = *ptr++; + mp_opt->addr.port = 0; + mp_opt->ahmac = 0; + if (mp_opt->addr.family == AF_INET) { + memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4); + ptr += 4; + if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT || + opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) { + mp_opt->addr.port = htons(get_unaligned_be16(ptr)); + ptr += 2; + } + } +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + else { + memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16); + ptr += 16; + if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT || + opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) { + mp_opt->addr.port = htons(get_unaligned_be16(ptr)); + ptr += 2; + } + } +#endif + if (!mp_opt->echo) { + mp_opt->ahmac = get_unaligned_be64(ptr); + ptr += 8; + } + pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d", + (mp_opt->addr.family == AF_INET6) ? "6" : "", + mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port)); + break; + + case MPTCPOPT_RM_ADDR: + if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 || + opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX) + break; + + ptr++; + + mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR; + mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE; + for (i = 0; i < mp_opt->rm_list.nr; i++) + mp_opt->rm_list.ids[i] = *ptr++; + pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr); + break; + + case MPTCPOPT_MP_PRIO: + if (opsize != TCPOLEN_MPTCP_PRIO) + break; + + mp_opt->suboptions |= OPTION_MPTCP_PRIO; + mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP; + pr_debug("MP_PRIO: prio=%d", mp_opt->backup); + break; + + case MPTCPOPT_MP_FASTCLOSE: + if (opsize != TCPOLEN_MPTCP_FASTCLOSE) + break; + + ptr += 2; + mp_opt->rcvr_key = get_unaligned_be64(ptr); + ptr += 8; + mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE; + pr_debug("MP_FASTCLOSE: recv_key=%llu", mp_opt->rcvr_key); + break; + + case MPTCPOPT_RST: + if (opsize != TCPOLEN_MPTCP_RST) + break; + + if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) + break; + + mp_opt->suboptions |= OPTION_MPTCP_RST; + flags = *ptr++; + mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT; + mp_opt->reset_reason = *ptr; + pr_debug("MP_RST: transient=%u reason=%u", + mp_opt->reset_transient, mp_opt->reset_reason); + break; + + case MPTCPOPT_MP_FAIL: + if (opsize != TCPOLEN_MPTCP_FAIL) + break; + + ptr += 2; + mp_opt->suboptions |= OPTION_MPTCP_FAIL; + mp_opt->fail_seq = get_unaligned_be64(ptr); + pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq); + break; + + default: + break; + } +} + +void mptcp_get_options(const struct sk_buff *skb, + struct mptcp_options_received *mp_opt) +{ + const struct tcphdr *th = tcp_hdr(skb); + const unsigned char *ptr; + int length; + + /* initialize option status */ + mp_opt->suboptions = 0; + + length = (th->doff * 4) - sizeof(struct tcphdr); + ptr = (const unsigned char *)(th + 1); + + while (length > 0) { + int opcode = *ptr++; + int opsize; + + switch (opcode) { + case TCPOPT_EOL: + return; + case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */ + length--; + continue; + default: + if (length < 2) + return; + opsize = *ptr++; + if (opsize < 2) /* "silly options" */ + return; + if (opsize > length) + return; /* don't parse partial options */ + if (opcode == TCPOPT_MPTCP) + mptcp_parse_option(skb, ptr, opsize, mp_opt); + ptr += opsize - 2; + length -= opsize; + } + } +} + +bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb, + unsigned int *size, struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + + /* we will use snd_isn to detect first pkt [re]transmission + * in mptcp_established_options_mp() + */ + subflow->snd_isn = TCP_SKB_CB(skb)->end_seq; + if (subflow->request_mptcp) { + opts->suboptions = OPTION_MPTCP_MPC_SYN; + opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk)); + opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); + *size = TCPOLEN_MPTCP_MPC_SYN; + return true; + } else if (subflow->request_join) { + pr_debug("remote_token=%u, nonce=%u", subflow->remote_token, + subflow->local_nonce); + opts->suboptions = OPTION_MPTCP_MPJ_SYN; + opts->join_id = subflow->local_id; + opts->token = subflow->remote_token; + opts->nonce = subflow->local_nonce; + opts->backup = subflow->request_bkup; + *size = TCPOLEN_MPTCP_MPJ_SYN; + return true; + } + return false; +} + +static void clear_3rdack_retransmission(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + sk_stop_timer(sk, &icsk->icsk_delack_timer); + icsk->icsk_ack.timeout = 0; + icsk->icsk_ack.ato = 0; + icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER); +} + +static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, + bool snd_data_fin_enable, + unsigned int *size, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + struct mptcp_ext *mpext; + unsigned int data_len; + u8 len; + + /* When skb is not available, we better over-estimate the emitted + * options len. A full DSS option (28 bytes) is longer than + * TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so + * tell the caller to defer the estimate to + * mptcp_established_options_dss(), which will reserve enough space. + */ + if (!skb) + return false; + + /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */ + if (subflow->fully_established || snd_data_fin_enable || + subflow->snd_isn != TCP_SKB_CB(skb)->seq || + sk->sk_state != TCP_ESTABLISHED) + return false; + + if (subflow->mp_capable) { + mpext = mptcp_get_ext(skb); + data_len = mpext ? mpext->data_len : 0; + + /* we will check ops->data_len in mptcp_write_options() to + * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and + * TCPOLEN_MPTCP_MPC_ACK + */ + opts->data_len = data_len; + opts->suboptions = OPTION_MPTCP_MPC_ACK; + opts->sndr_key = subflow->local_key; + opts->rcvr_key = subflow->remote_key; + opts->csum_reqd = READ_ONCE(msk->csum_enabled); + opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk)); + + /* Section 3.1. + * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK + * packets that start the first subflow of an MPTCP connection, + * as well as the first packet that carries data + */ + if (data_len > 0) { + len = TCPOLEN_MPTCP_MPC_ACK_DATA; + if (opts->csum_reqd) { + /* we need to propagate more info to csum the pseudo hdr */ + opts->data_seq = mpext->data_seq; + opts->subflow_seq = mpext->subflow_seq; + opts->csum = mpext->csum; + len += TCPOLEN_MPTCP_DSS_CHECKSUM; + } + *size = ALIGN(len, 4); + } else { + *size = TCPOLEN_MPTCP_MPC_ACK; + } + + pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d", + subflow, subflow->local_key, subflow->remote_key, + data_len); + + return true; + } else if (subflow->mp_join) { + opts->suboptions = OPTION_MPTCP_MPJ_ACK; + memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN); + *size = TCPOLEN_MPTCP_MPJ_ACK; + pr_debug("subflow=%p", subflow); + + /* we can use the full delegate action helper only from BH context + * If we are in process context - sk is flushing the backlog at + * socket lock release time - just set the appropriate flag, will + * be handled by the release callback + */ + if (sock_owned_by_user(sk)) + set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status); + else + mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK); + return true; + } + return false; +} + +static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, + struct sk_buff *skb, struct mptcp_ext *ext) +{ + /* The write_seq value has already been incremented, so the actual + * sequence number for the DATA_FIN is one less. + */ + u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; + + if (!ext->use_map || !skb->len) { + /* RFC6824 requires a DSS mapping with specific values + * if DATA_FIN is set but no data payload is mapped + */ + ext->data_fin = 1; + ext->use_map = 1; + ext->dsn64 = 1; + ext->data_seq = data_fin_tx_seq; + ext->subflow_seq = 0; + ext->data_len = 1; + } else if (ext->data_seq + ext->data_len == data_fin_tx_seq) { + /* If there's an existing DSS mapping and it is the + * final mapping, DATA_FIN consumes 1 additional byte of + * mapping space. + */ + ext->data_fin = 1; + ext->data_len++; + } +} + +static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, + bool snd_data_fin_enable, + unsigned int *size, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + unsigned int dss_size = 0; + struct mptcp_ext *mpext; + unsigned int ack_size; + bool ret = false; + u64 ack_seq; + + opts->csum_reqd = READ_ONCE(msk->csum_enabled); + mpext = skb ? mptcp_get_ext(skb) : NULL; + + if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) { + unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64; + + if (mpext) { + if (opts->csum_reqd) + map_size += TCPOLEN_MPTCP_DSS_CHECKSUM; + + opts->ext_copy = *mpext; + } + + dss_size = map_size; + if (skb && snd_data_fin_enable) + mptcp_write_data_fin(subflow, skb, &opts->ext_copy); + opts->suboptions = OPTION_MPTCP_DSS; + ret = true; + } + + /* passive sockets msk will set the 'can_ack' after accept(), even + * if the first subflow may have the already the remote key handy + */ + opts->ext_copy.use_ack = 0; + if (!READ_ONCE(msk->can_ack)) { + *size = ALIGN(dss_size, 4); + return ret; + } + + ack_seq = READ_ONCE(msk->ack_seq); + if (READ_ONCE(msk->use_64bit_ack)) { + ack_size = TCPOLEN_MPTCP_DSS_ACK64; + opts->ext_copy.data_ack = ack_seq; + opts->ext_copy.ack64 = 1; + } else { + ack_size = TCPOLEN_MPTCP_DSS_ACK32; + opts->ext_copy.data_ack32 = (uint32_t)ack_seq; + opts->ext_copy.ack64 = 0; + } + opts->ext_copy.use_ack = 1; + opts->suboptions = OPTION_MPTCP_DSS; + WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk)); + + /* Add kind/length/subtype/flag overhead if mapping is not populated */ + if (dss_size == 0) + ack_size += TCPOLEN_MPTCP_DSS_BASE; + + dss_size += ack_size; + + *size = ALIGN(dss_size, 4); + return true; +} + +static u64 add_addr_generate_hmac(u64 key1, u64 key2, + struct mptcp_addr_info *addr) +{ + u16 port = ntohs(addr->port); + u8 hmac[SHA256_DIGEST_SIZE]; + u8 msg[19]; + int i = 0; + + msg[i++] = addr->id; + if (addr->family == AF_INET) { + memcpy(&msg[i], &addr->addr.s_addr, 4); + i += 4; + } +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + else if (addr->family == AF_INET6) { + memcpy(&msg[i], &addr->addr6.s6_addr, 16); + i += 16; + } +#endif + msg[i++] = port >> 8; + msg[i++] = port & 0xFF; + + mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac); + + return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]); +} + +static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + bool drop_other_suboptions = false; + unsigned int opt_size = *size; + bool echo; + int len; + + /* add addr will strip the existing options, be sure to avoid breaking + * MPC/MPJ handshakes + */ + if (!mptcp_pm_should_add_signal(msk) || + (opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) || + !mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr, + &echo, &drop_other_suboptions)) + return false; + + if (drop_other_suboptions) + remaining += opt_size; + len = mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port); + if (remaining < len) + return false; + + *size = len; + if (drop_other_suboptions) { + pr_debug("drop other suboptions"); + opts->suboptions = 0; + + /* note that e.g. DSS could have written into the memory + * aliased by ahmac, we must reset the field here + * to avoid appending the hmac even for ADD_ADDR echo + * options + */ + opts->ahmac = 0; + *size -= opt_size; + } + opts->suboptions |= OPTION_MPTCP_ADD_ADDR; + if (!echo) { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX); + opts->ahmac = add_addr_generate_hmac(msk->local_key, + msk->remote_key, + &opts->addr); + } else { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADDTX); + } + pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d", + opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port)); + + return true; +} + +static bool mptcp_established_options_rm_addr(struct sock *sk, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + struct mptcp_rm_list rm_list; + int i, len; + + if (!mptcp_pm_should_rm_signal(msk) || + !(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list))) + return false; + + len = mptcp_rm_addr_len(&rm_list); + if (len < 0) + return false; + if (remaining < len) + return false; + + *size = len; + opts->suboptions |= OPTION_MPTCP_RM_ADDR; + opts->rm_list = rm_list; + + for (i = 0; i < opts->rm_list.nr; i++) + pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]); + MPTCP_ADD_STATS(sock_net(sk), MPTCP_MIB_RMADDRTX, opts->rm_list.nr); + return true; +} + +static bool mptcp_established_options_mp_prio(struct sock *sk, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + + /* can't send MP_PRIO with MPC, as they share the same option space: + * 'backup'. Also it makes no sense at all + */ + if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC)) + return false; + + /* account for the trailing 'nop' option */ + if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN) + return false; + + *size = TCPOLEN_MPTCP_PRIO_ALIGN; + opts->suboptions |= OPTION_MPTCP_PRIO; + opts->backup = subflow->request_bkup; + + pr_debug("prio=%d", opts->backup); + + return true; +} + +static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + + if (remaining < TCPOLEN_MPTCP_RST) + return false; + + *size = TCPOLEN_MPTCP_RST; + opts->suboptions |= OPTION_MPTCP_RST; + opts->reset_transient = subflow->reset_transient; + opts->reset_reason = subflow->reset_reason; + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX); + + return true; +} + +static bool mptcp_established_options_fastclose(struct sock *sk, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + + if (likely(!subflow->send_fastclose)) + return false; + + if (remaining < TCPOLEN_MPTCP_FASTCLOSE) + return false; + + *size = TCPOLEN_MPTCP_FASTCLOSE; + opts->suboptions |= OPTION_MPTCP_FASTCLOSE; + opts->rcvr_key = msk->remote_key; + + pr_debug("FASTCLOSE key=%llu", opts->rcvr_key); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX); + return true; +} + +static bool mptcp_established_options_mp_fail(struct sock *sk, + unsigned int *size, + unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + + if (likely(!subflow->send_mp_fail)) + return false; + + if (remaining < TCPOLEN_MPTCP_FAIL) + return false; + + *size = TCPOLEN_MPTCP_FAIL; + opts->suboptions |= OPTION_MPTCP_FAIL; + opts->fail_seq = subflow->map_seq; + + pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX); + + return true; +} + +bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, + unsigned int *size, unsigned int remaining, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + unsigned int opt_size = 0; + bool snd_data_fin; + bool ret = false; + + opts->suboptions = 0; + + if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb))) + return false; + + if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) { + if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) || + mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) { + *size += opt_size; + remaining -= opt_size; + } + /* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */ + if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) { + *size += opt_size; + remaining -= opt_size; + } + return true; + } + + snd_data_fin = mptcp_data_fin_enabled(msk); + if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts)) + ret = true; + else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) { + unsigned int mp_fail_size; + + ret = true; + if (mptcp_established_options_mp_fail(sk, &mp_fail_size, + remaining - opt_size, opts)) { + *size += opt_size + mp_fail_size; + remaining -= opt_size - mp_fail_size; + return true; + } + } + + /* we reserved enough space for the above options, and exceeding the + * TCP option space would be fatal + */ + if (WARN_ON_ONCE(opt_size > remaining)) + return false; + + *size += opt_size; + remaining -= opt_size; + if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) { + *size += opt_size; + remaining -= opt_size; + ret = true; + } else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) { + *size += opt_size; + remaining -= opt_size; + ret = true; + } + + if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) { + *size += opt_size; + remaining -= opt_size; + ret = true; + } + + return ret; +} + +bool mptcp_synack_options(const struct request_sock *req, unsigned int *size, + struct mptcp_out_options *opts) +{ + struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); + + if (subflow_req->mp_capable) { + opts->suboptions = OPTION_MPTCP_MPC_SYNACK; + opts->sndr_key = subflow_req->local_key; + opts->csum_reqd = subflow_req->csum_reqd; + opts->allow_join_id0 = subflow_req->allow_join_id0; + *size = TCPOLEN_MPTCP_MPC_SYNACK; + pr_debug("subflow_req=%p, local_key=%llu", + subflow_req, subflow_req->local_key); + return true; + } else if (subflow_req->mp_join) { + opts->suboptions = OPTION_MPTCP_MPJ_SYNACK; + opts->backup = subflow_req->backup; + opts->join_id = subflow_req->local_id; + opts->thmac = subflow_req->thmac; + opts->nonce = subflow_req->local_nonce; + pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u", + subflow_req, opts->backup, opts->join_id, + opts->thmac, opts->nonce); + *size = TCPOLEN_MPTCP_MPJ_SYNACK; + return true; + } + return false; +} + +static bool 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) +{ + /* here we can process OoO, in-window pkts, only in-sequence 4th ack + * will make the subflow fully established + */ + if (likely(subflow->fully_established)) { + /* on passive sockets, check for 3rd ack retransmission + * note that msk is always set by subflow_syn_recv_sock() + * for mp_join subflows + */ + if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 && + TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq && + subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) && + !subflow->request_join) + tcp_send_ack(ssk); + goto check_notify; + } + + /* we must process OoO packets before the first subflow is fully + * established. OoO packets are instead a protocol violation + * for MP_JOIN subflows as the peer must not send any data + * before receiving the forth ack - cfr. RFC 8684 section 3.2. + */ + if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) { + if (subflow->mp_join) + goto reset; + if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) + goto set_fully_established; + return subflow->mp_capable; + } + + if (subflow->remote_key_valid && + (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) || + ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo))) { + /* subflows are fully established as soon as we get any + * additional ack, including ADD_ADDR. + */ + subflow->fully_established = 1; + WRITE_ONCE(msk->fully_established, true); + goto check_notify; + } + + /* If the first established packet does not contain MP_CAPABLE + data + * then fallback to TCP. Fallback scenarios requires a reset for + * MP_JOIN subflows. + */ + if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) { + if (subflow->mp_join) + goto reset; + subflow->mp_capable = 0; + pr_fallback(msk); + mptcp_do_fallback(ssk); + return false; + } + + if (mp_opt->deny_join_id0) + WRITE_ONCE(msk->pm.remote_deny_join_id0, true); + +set_fully_established: + if (unlikely(!READ_ONCE(msk->pm.server_side))) + pr_warn_once("bogus mpc option on established client sk"); + mptcp_subflow_fully_established(subflow, mp_opt); + +check_notify: + /* if the subflow is not already linked into the conn_list, we can't + * notify the PM: this subflow is still on the listener queue + * and the PM possibly acquiring the subflow lock could race with + * the listener close + */ + if (likely(subflow->pm_notified) || list_empty(&subflow->node)) + return true; + + subflow->pm_notified = 1; + if (subflow->mp_join) { + clear_3rdack_retransmission(ssk); + mptcp_pm_subflow_established(msk); + } else { + mptcp_pm_fully_established(msk, ssk); + } + return true; + +reset: + mptcp_subflow_reset(ssk); + return false; +} + +u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) +{ + u32 old_seq32, cur_seq32; + + old_seq32 = (u32)old_seq; + cur_seq32 = (u32)cur_seq; + cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32; + if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32))) + return cur_seq + (1LL << 32); + + /* reverse wrap could happen, too */ + if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32))) + return cur_seq - (1LL << 32); + return cur_seq; +} + +static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una) +{ + msk->bytes_acked += new_snd_una - msk->snd_una; + msk->snd_una = new_snd_una; +} + +static void ack_update_msk(struct mptcp_sock *msk, + struct sock *ssk, + struct mptcp_options_received *mp_opt) +{ + u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt); + struct sock *sk = (struct sock *)msk; + u64 old_snd_una; + + mptcp_data_lock(sk); + + /* avoid ack expansion on update conflict, to reduce the risk of + * wrongly expanding to a future ack sequence number, which is way + * more dangerous than missing an ack + */ + old_snd_una = msk->snd_una; + new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64); + + /* ACK for data not even sent yet? Ignore.*/ + if (unlikely(after64(new_snd_una, snd_nxt))) + new_snd_una = old_snd_una; + + new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd; + + if (after64(new_wnd_end, msk->wnd_end)) + msk->wnd_end = new_wnd_end; + + /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ + if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt))) + __mptcp_check_push(sk, ssk); + + if (after64(new_snd_una, old_snd_una)) { + __mptcp_snd_una_update(msk, new_snd_una); + __mptcp_data_acked(sk); + } + mptcp_data_unlock(sk); + + trace_ack_update_msk(mp_opt->data_ack, + old_snd_una, new_snd_una, + new_wnd_end, msk->wnd_end); +} + +bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit) +{ + /* Skip if DATA_FIN was already received. + * If updating simultaneously with the recvmsg loop, values + * should match. If they mismatch, the peer is misbehaving and + * we will prefer the most recent information. + */ + if (READ_ONCE(msk->rcv_data_fin)) + return false; + + WRITE_ONCE(msk->rcv_data_fin_seq, + mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); + WRITE_ONCE(msk->rcv_data_fin, 1); + + return true; +} + +static bool add_addr_hmac_valid(struct mptcp_sock *msk, + struct mptcp_options_received *mp_opt) +{ + u64 hmac = 0; + + if (mp_opt->echo) + return true; + + hmac = add_addr_generate_hmac(msk->remote_key, + msk->local_key, + &mp_opt->addr); + + pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n", + msk, hmac, mp_opt->ahmac); + + return hmac == mp_opt->ahmac; +} + +/* Return false if a subflow has been reset, else return true */ +bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + struct mptcp_options_received mp_opt; + struct mptcp_ext *mpext; + + if (__mptcp_check_fallback(msk)) { + /* Keep it simple and unconditionally trigger send data cleanup and + * pending queue spooling. We will need to acquire the data lock + * for more accurate checks, and once the lock is acquired, such + * helpers are cheap. + */ + mptcp_data_lock(subflow->conn); + if (sk_stream_memory_free(sk)) + __mptcp_check_push(subflow->conn, sk); + + /* on fallback we just need to ignore the msk-level snd_una, as + * this is really plain TCP + */ + __mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt)); + + __mptcp_data_acked(subflow->conn); + mptcp_data_unlock(subflow->conn); + return true; + } + + mptcp_get_options(skb, &mp_opt); + + /* The subflow can be in close state only if check_fully_established() + * just sent a reset. If so, tell the caller to ignore the current packet. + */ + if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) + return sk->sk_state != TCP_CLOSE; + + if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) { + if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) && + msk->local_key == mp_opt.rcvr_key) { + WRITE_ONCE(msk->rcv_fastclose, true); + mptcp_schedule_work((struct sock *)msk); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX); + } + + if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) && + add_addr_hmac_valid(msk, &mp_opt)) { + if (!mp_opt.echo) { + mptcp_pm_add_addr_received(sk, &mp_opt.addr); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR); + } else { + mptcp_pm_add_addr_echoed(msk, &mp_opt.addr); + mptcp_pm_del_add_timer(msk, &mp_opt.addr, true); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD); + } + + if (mp_opt.addr.port) + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD); + } + + if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR) + mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list); + + if (mp_opt.suboptions & OPTION_MPTCP_PRIO) { + mptcp_pm_mp_prio_received(sk, mp_opt.backup); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX); + } + + if (mp_opt.suboptions & OPTION_MPTCP_FAIL) { + mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX); + } + + if (mp_opt.suboptions & OPTION_MPTCP_RST) { + subflow->reset_seen = 1; + subflow->reset_reason = mp_opt.reset_reason; + subflow->reset_transient = mp_opt.reset_transient; + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX); + } + + if (!(mp_opt.suboptions & OPTION_MPTCP_DSS)) + return true; + } + + /* we can't wait for recvmsg() to update the ack_seq, otherwise + * monodirectional flows will stuck + */ + if (mp_opt.use_ack) + ack_update_msk(msk, sk, &mp_opt); + + /* Zero-data-length packets are dropped by the caller and not + * propagated to the MPTCP layer, so the skb extension does not + * need to be allocated or populated. DATA_FIN information, if + * present, needs to be updated here before the skb is freed. + */ + if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) { + if (mp_opt.data_fin && mp_opt.data_len == 1 && + mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64)) + mptcp_schedule_work((struct sock *)msk); + + return true; + } + + mpext = skb_ext_add(skb, SKB_EXT_MPTCP); + if (!mpext) + return true; + + memset(mpext, 0, sizeof(*mpext)); + + if (likely(mp_opt.use_map)) { + if (mp_opt.mpc_map) { + /* this is an MP_CAPABLE carrying MPTCP data + * we know this map the first chunk of data + */ + mptcp_crypto_key_sha(subflow->remote_key, NULL, + &mpext->data_seq); + mpext->data_seq++; + mpext->subflow_seq = 1; + mpext->dsn64 = 1; + mpext->mpc_map = 1; + mpext->data_fin = 0; + } else { + mpext->data_seq = mp_opt.data_seq; + mpext->subflow_seq = mp_opt.subflow_seq; + mpext->dsn64 = mp_opt.dsn64; + mpext->data_fin = mp_opt.data_fin; + } + mpext->data_len = mp_opt.data_len; + mpext->use_map = 1; + mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD); + + if (mpext->csum_reqd) + mpext->csum = mp_opt.csum; + } + + return true; +} + +static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) +{ + const struct sock *ssk = (const struct sock *)tp; + struct mptcp_subflow_context *subflow; + u64 ack_seq, rcv_wnd_old, rcv_wnd_new; + struct mptcp_sock *msk; + u32 new_win; + u64 win; + + subflow = mptcp_subflow_ctx(ssk); + msk = mptcp_sk(subflow->conn); + + ack_seq = READ_ONCE(msk->ack_seq); + rcv_wnd_new = ack_seq + tp->rcv_wnd; + + rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent); + if (after64(rcv_wnd_new, rcv_wnd_old)) { + u64 rcv_wnd; + + for (;;) { + rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new); + + if (rcv_wnd == rcv_wnd_old) + break; + + rcv_wnd_old = rcv_wnd; + if (before64(rcv_wnd_new, rcv_wnd_old)) { + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE); + goto raise_win; + } + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT); + } + return; + } + + if (rcv_wnd_new != rcv_wnd_old) { +raise_win: + win = rcv_wnd_old - ack_seq; + tp->rcv_wnd = min_t(u64, win, U32_MAX); + new_win = tp->rcv_wnd; + + /* Make sure we do not exceed the maximum possible + * scaled window. + */ + if (unlikely(th->syn)) + new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale; + if (!tp->rx_opt.rcv_wscale && + READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)) + new_win = min(new_win, MAX_TCP_WINDOW); + else + new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); + + /* RFC1323 scaling applied */ + new_win >>= tp->rx_opt.rcv_wscale; + th->window = htons(new_win); + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED); + } +} + +__sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum) +{ + struct csum_pseudo_header header; + __wsum csum; + + /* cfr RFC 8684 3.3.1.: + * the data sequence number used in the pseudo-header is + * always the 64-bit value, irrespective of what length is used in the + * DSS option itself. + */ + header.data_seq = cpu_to_be64(data_seq); + header.subflow_seq = htonl(subflow_seq); + header.data_len = htons(data_len); + header.csum = 0; + + csum = csum_partial(&header, sizeof(header), sum); + return csum_fold(csum); +} + +static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext) +{ + return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len, + ~csum_unfold(mpext->csum)); +} + +static void put_len_csum(u16 len, __sum16 csum, void *data) +{ + __sum16 *sumptr = data + 2; + __be16 *ptr = data; + + put_unaligned_be16(len, ptr); + + put_unaligned(csum, sumptr); +} + +void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp, + struct mptcp_out_options *opts) +{ + const struct sock *ssk = (const struct sock *)tp; + struct mptcp_subflow_context *subflow; + + /* Which options can be used together? + * + * X: mutually exclusive + * O: often used together + * C: can be used together in some cases + * P: could be used together but we prefer not to (optimisations) + * + * Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | + * ------|------|------|------|------|------|------|------|------| + * MPC |------|------|------|------|------|------|------|------| + * MPJ | X |------|------|------|------|------|------|------| + * DSS | X | X |------|------|------|------|------|------| + * ADD | X | X | P |------|------|------|------|------| + * RM | C | C | C | P |------|------|------|------| + * PRIO | X | C | C | C | C |------|------|------| + * FAIL | X | X | C | X | X | X |------|------| + * FC | X | X | X | X | X | X | X |------| + * RST | X | X | X | X | X | X | O | O | + * ------|------|------|------|------|------|------|------|------| + * + * The same applies in mptcp_established_options() function. + */ + if (likely(OPTION_MPTCP_DSS & opts->suboptions)) { + struct mptcp_ext *mpext = &opts->ext_copy; + u8 len = TCPOLEN_MPTCP_DSS_BASE; + u8 flags = 0; + + if (mpext->use_ack) { + flags = MPTCP_DSS_HAS_ACK; + if (mpext->ack64) { + len += TCPOLEN_MPTCP_DSS_ACK64; + flags |= MPTCP_DSS_ACK64; + } else { + len += TCPOLEN_MPTCP_DSS_ACK32; + } + } + + if (mpext->use_map) { + len += TCPOLEN_MPTCP_DSS_MAP64; + + /* Use only 64-bit mapping flags for now, add + * support for optional 32-bit mappings later. + */ + flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64; + if (mpext->data_fin) + flags |= MPTCP_DSS_DATA_FIN; + + if (opts->csum_reqd) + len += TCPOLEN_MPTCP_DSS_CHECKSUM; + } + + *ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags); + + if (mpext->use_ack) { + if (mpext->ack64) { + put_unaligned_be64(mpext->data_ack, ptr); + ptr += 2; + } else { + put_unaligned_be32(mpext->data_ack32, ptr); + ptr += 1; + } + } + + if (mpext->use_map) { + put_unaligned_be64(mpext->data_seq, ptr); + ptr += 2; + put_unaligned_be32(mpext->subflow_seq, ptr); + ptr += 1; + if (opts->csum_reqd) { + /* data_len == 0 is reserved for the infinite mapping, + * the checksum will also be set to 0. + */ + put_len_csum(mpext->data_len, + (mpext->data_len ? mptcp_make_csum(mpext) : 0), + ptr); + } else { + put_unaligned_be32(mpext->data_len << 16 | + TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); + } + ptr += 1; + } + + /* We might need to add MP_FAIL options in rare cases */ + if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) + goto mp_fail; + } else if (OPTIONS_MPTCP_MPC & opts->suboptions) { + u8 len, flag = MPTCP_CAP_HMAC_SHA256; + + if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { + len = TCPOLEN_MPTCP_MPC_SYN; + } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { + len = TCPOLEN_MPTCP_MPC_SYNACK; + } else if (opts->data_len) { + len = TCPOLEN_MPTCP_MPC_ACK_DATA; + if (opts->csum_reqd) + len += TCPOLEN_MPTCP_DSS_CHECKSUM; + } else { + len = TCPOLEN_MPTCP_MPC_ACK; + } + + if (opts->csum_reqd) + flag |= MPTCP_CAP_CHECKSUM_REQD; + + if (!opts->allow_join_id0) + flag |= MPTCP_CAP_DENY_JOIN_ID0; + + *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, + MPTCP_SUPPORTED_VERSION, + flag); + + if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) & + opts->suboptions)) + goto mp_capable_done; + + put_unaligned_be64(opts->sndr_key, ptr); + ptr += 2; + if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions)) + goto mp_capable_done; + + put_unaligned_be64(opts->rcvr_key, ptr); + ptr += 2; + if (!opts->data_len) + goto mp_capable_done; + + if (opts->csum_reqd) { + put_len_csum(opts->data_len, + __mptcp_make_csum(opts->data_seq, + opts->subflow_seq, + opts->data_len, + ~csum_unfold(opts->csum)), + ptr); + } else { + put_unaligned_be32(opts->data_len << 16 | + TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); + } + ptr += 1; + + /* MPC is additionally mutually exclusive with MP_PRIO */ + goto mp_capable_done; + } else if (OPTIONS_MPTCP_MPJ & opts->suboptions) { + if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) { + *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, + TCPOLEN_MPTCP_MPJ_SYN, + opts->backup, opts->join_id); + put_unaligned_be32(opts->token, ptr); + ptr += 1; + put_unaligned_be32(opts->nonce, ptr); + ptr += 1; + } else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) { + *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, + TCPOLEN_MPTCP_MPJ_SYNACK, + opts->backup, opts->join_id); + put_unaligned_be64(opts->thmac, ptr); + ptr += 2; + put_unaligned_be32(opts->nonce, ptr); + ptr += 1; + } else { + *ptr++ = mptcp_option(MPTCPOPT_MP_JOIN, + TCPOLEN_MPTCP_MPJ_ACK, 0, 0); + memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN); + ptr += 5; + } + } else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) { + u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE; + u8 echo = MPTCP_ADDR_ECHO; + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + if (opts->addr.family == AF_INET6) + len = TCPOLEN_MPTCP_ADD_ADDR6_BASE; +#endif + + if (opts->addr.port) + len += TCPOLEN_MPTCP_PORT_LEN; + + if (opts->ahmac) { + len += sizeof(opts->ahmac); + echo = 0; + } + + *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, + len, echo, opts->addr.id); + if (opts->addr.family == AF_INET) { + memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4); + ptr += 1; + } +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + else if (opts->addr.family == AF_INET6) { + memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16); + ptr += 4; + } +#endif + + if (!opts->addr.port) { + if (opts->ahmac) { + put_unaligned_be64(opts->ahmac, ptr); + ptr += 2; + } + } else { + u16 port = ntohs(opts->addr.port); + + if (opts->ahmac) { + u8 *bptr = (u8 *)ptr; + + put_unaligned_be16(port, bptr); + bptr += 2; + put_unaligned_be64(opts->ahmac, bptr); + bptr += 8; + put_unaligned_be16(TCPOPT_NOP << 8 | + TCPOPT_NOP, bptr); + + ptr += 3; + } else { + put_unaligned_be32(port << 16 | + TCPOPT_NOP << 8 | + TCPOPT_NOP, ptr); + ptr += 1; + } + } + } else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) { + /* FASTCLOSE is mutually exclusive with others except RST */ + *ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE, + TCPOLEN_MPTCP_FASTCLOSE, + 0, 0); + put_unaligned_be64(opts->rcvr_key, ptr); + ptr += 2; + + if (OPTION_MPTCP_RST & opts->suboptions) + goto mp_rst; + return; + } else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) { +mp_fail: + /* MP_FAIL is mutually exclusive with others except RST */ + subflow = mptcp_subflow_ctx(ssk); + subflow->send_mp_fail = 0; + + *ptr++ = mptcp_option(MPTCPOPT_MP_FAIL, + TCPOLEN_MPTCP_FAIL, + 0, 0); + put_unaligned_be64(opts->fail_seq, ptr); + ptr += 2; + + if (OPTION_MPTCP_RST & opts->suboptions) + goto mp_rst; + return; + } else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) { +mp_rst: + *ptr++ = mptcp_option(MPTCPOPT_RST, + TCPOLEN_MPTCP_RST, + opts->reset_transient, + opts->reset_reason); + return; + } + + if (OPTION_MPTCP_PRIO & opts->suboptions) { + subflow = mptcp_subflow_ctx(ssk); + subflow->send_mp_prio = 0; + + *ptr++ = mptcp_option(MPTCPOPT_MP_PRIO, + TCPOLEN_MPTCP_PRIO, + opts->backup, TCPOPT_NOP); + + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX); + } + +mp_capable_done: + if (OPTION_MPTCP_RM_ADDR & opts->suboptions) { + u8 i = 1; + + *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, + TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr, + 0, opts->rm_list.ids[0]); + + while (i < opts->rm_list.nr) { + u8 id1, id2, id3, id4; + + id1 = opts->rm_list.ids[i]; + id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP; + id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP; + id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP; + put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr); + ptr += 1; + i += 4; + } + } + + if (tp) + mptcp_set_rwin(tp, th); +} + +__be32 mptcp_get_reset_option(const struct sk_buff *skb) +{ + const struct mptcp_ext *ext = mptcp_get_ext(skb); + u8 flags, reason; + + if (ext) { + flags = ext->reset_transient; + reason = ext->reset_reason; + + return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST, + flags, reason); + } + + return htonl(0u); +} +EXPORT_SYMBOL_GPL(mptcp_get_reset_option); |