mirror of https://gitee.com/openkylin/linux.git
590 lines
15 KiB
C
590 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Multipath TCP
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*
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* Copyright (c) 2017 - 2019, Intel Corporation.
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*/
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#include <linux/kernel.h>
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#include <net/tcp.h>
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#include <net/mptcp.h>
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#include "protocol.h"
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static bool mptcp_cap_flag_sha256(u8 flags)
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{
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return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
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}
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void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
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int opsize, struct tcp_options_received *opt_rx)
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{
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struct mptcp_options_received *mp_opt = &opt_rx->mptcp;
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u8 subtype = *ptr >> 4;
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int expected_opsize;
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u8 version;
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u8 flags;
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switch (subtype) {
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case MPTCPOPT_MP_CAPABLE:
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/* strict size checking */
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if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
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if (skb->len > tcp_hdr(skb)->doff << 2)
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expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
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else
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expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
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} else {
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if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
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expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
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else
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expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
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}
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if (opsize != expected_opsize)
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break;
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/* try to be gentle vs future versions on the initial syn */
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version = *ptr++ & MPTCP_VERSION_MASK;
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if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
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if (version != MPTCP_SUPPORTED_VERSION)
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break;
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} else if (version < MPTCP_SUPPORTED_VERSION) {
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break;
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}
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flags = *ptr++;
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if (!mptcp_cap_flag_sha256(flags) ||
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(flags & MPTCP_CAP_EXTENSIBILITY))
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break;
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/* RFC 6824, Section 3.1:
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* "For the Checksum Required bit (labeled "A"), if either
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* host requires the use of checksums, checksums MUST be used.
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* In other words, the only way for checksums not to be used
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* is if both hosts in their SYNs set A=0."
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*
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* Section 3.3.0:
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* "If a checksum is not present when its use has been
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* negotiated, the receiver MUST close the subflow with a RST as
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* it is considered broken."
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*
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* We don't implement DSS checksum - fall back to TCP.
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*/
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if (flags & MPTCP_CAP_CHECKSUM_REQD)
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break;
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mp_opt->mp_capable = 1;
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if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
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mp_opt->sndr_key = get_unaligned_be64(ptr);
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ptr += 8;
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}
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if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
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mp_opt->rcvr_key = get_unaligned_be64(ptr);
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ptr += 8;
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}
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if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA) {
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/* Section 3.1.:
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* "the data parameters in a MP_CAPABLE are semantically
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* equivalent to those in a DSS option and can be used
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* interchangeably."
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*/
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mp_opt->dss = 1;
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mp_opt->use_map = 1;
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mp_opt->mpc_map = 1;
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mp_opt->data_len = get_unaligned_be16(ptr);
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ptr += 2;
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}
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pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
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version, flags, opsize, mp_opt->sndr_key,
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mp_opt->rcvr_key, mp_opt->data_len);
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break;
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case MPTCPOPT_DSS:
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pr_debug("DSS");
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ptr++;
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/* we must clear 'mpc_map' be able to detect MP_CAPABLE
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* map vs DSS map in mptcp_incoming_options(), and reconstruct
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* map info accordingly
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*/
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mp_opt->mpc_map = 0;
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flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
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mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
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mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
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mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
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mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
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mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
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pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
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mp_opt->data_fin, mp_opt->dsn64,
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mp_opt->use_map, mp_opt->ack64,
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mp_opt->use_ack);
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expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
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if (mp_opt->use_ack) {
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if (mp_opt->ack64)
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expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
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else
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expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
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}
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if (mp_opt->use_map) {
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if (mp_opt->dsn64)
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expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
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else
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expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
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}
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/* RFC 6824, Section 3.3:
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* If a checksum is present, but its use had
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* not been negotiated in the MP_CAPABLE handshake,
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* the checksum field MUST be ignored.
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*/
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if (opsize != expected_opsize &&
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opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
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break;
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mp_opt->dss = 1;
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if (mp_opt->use_ack) {
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if (mp_opt->ack64) {
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mp_opt->data_ack = get_unaligned_be64(ptr);
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ptr += 8;
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} else {
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mp_opt->data_ack = get_unaligned_be32(ptr);
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ptr += 4;
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}
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pr_debug("data_ack=%llu", mp_opt->data_ack);
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}
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if (mp_opt->use_map) {
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if (mp_opt->dsn64) {
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mp_opt->data_seq = get_unaligned_be64(ptr);
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ptr += 8;
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} else {
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mp_opt->data_seq = get_unaligned_be32(ptr);
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ptr += 4;
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}
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mp_opt->subflow_seq = get_unaligned_be32(ptr);
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ptr += 4;
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mp_opt->data_len = get_unaligned_be16(ptr);
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ptr += 2;
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pr_debug("data_seq=%llu subflow_seq=%u data_len=%u",
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mp_opt->data_seq, mp_opt->subflow_seq,
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mp_opt->data_len);
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}
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break;
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default:
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break;
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}
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}
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void mptcp_get_options(const struct sk_buff *skb,
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struct tcp_options_received *opt_rx)
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{
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const unsigned char *ptr;
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const struct tcphdr *th = tcp_hdr(skb);
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int length = (th->doff * 4) - sizeof(struct tcphdr);
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ptr = (const unsigned char *)(th + 1);
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while (length > 0) {
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int opcode = *ptr++;
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int opsize;
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switch (opcode) {
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case TCPOPT_EOL:
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return;
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case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
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length--;
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continue;
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default:
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opsize = *ptr++;
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if (opsize < 2) /* "silly options" */
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return;
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if (opsize > length)
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return; /* don't parse partial options */
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if (opcode == TCPOPT_MPTCP)
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mptcp_parse_option(skb, ptr, opsize, opt_rx);
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ptr += opsize - 2;
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length -= opsize;
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}
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}
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}
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bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
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unsigned int *size, struct mptcp_out_options *opts)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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/* we will use snd_isn to detect first pkt [re]transmission
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* in mptcp_established_options_mp()
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*/
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subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
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if (subflow->request_mptcp) {
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pr_debug("local_key=%llu", subflow->local_key);
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opts->suboptions = OPTION_MPTCP_MPC_SYN;
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opts->sndr_key = subflow->local_key;
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*size = TCPOLEN_MPTCP_MPC_SYN;
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return true;
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}
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return false;
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}
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void mptcp_rcv_synsent(struct sock *sk)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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struct tcp_sock *tp = tcp_sk(sk);
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pr_debug("subflow=%p", subflow);
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if (subflow->request_mptcp && tp->rx_opt.mptcp.mp_capable) {
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subflow->mp_capable = 1;
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subflow->can_ack = 1;
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subflow->remote_key = tp->rx_opt.mptcp.sndr_key;
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} else {
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tcp_sk(sk)->is_mptcp = 0;
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}
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}
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static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
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unsigned int *size,
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unsigned int remaining,
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struct mptcp_out_options *opts)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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struct mptcp_ext *mpext;
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unsigned int data_len;
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pr_debug("subflow=%p fully established=%d seq=%x:%x remaining=%d",
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subflow, subflow->fully_established, subflow->snd_isn,
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skb ? TCP_SKB_CB(skb)->seq : 0, remaining);
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if (subflow->mp_capable && !subflow->fully_established && skb &&
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subflow->snd_isn == TCP_SKB_CB(skb)->seq) {
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/* When skb is not available, we better over-estimate the
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* emitted options len. A full DSS option is longer than
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* TCPOLEN_MPTCP_MPC_ACK_DATA, so let's the caller try to fit
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* that.
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*/
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mpext = mptcp_get_ext(skb);
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data_len = mpext ? mpext->data_len : 0;
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/* we will check ext_copy.data_len in mptcp_write_options() to
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* discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
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* TCPOLEN_MPTCP_MPC_ACK
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*/
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opts->ext_copy.data_len = data_len;
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opts->suboptions = OPTION_MPTCP_MPC_ACK;
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opts->sndr_key = subflow->local_key;
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opts->rcvr_key = subflow->remote_key;
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/* Section 3.1.
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* The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
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* packets that start the first subflow of an MPTCP connection,
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* as well as the first packet that carries data
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*/
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if (data_len > 0)
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*size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4);
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else
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*size = TCPOLEN_MPTCP_MPC_ACK;
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pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
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subflow, subflow->local_key, subflow->remote_key,
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data_len);
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return true;
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}
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return false;
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}
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static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
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struct mptcp_ext *ext)
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{
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if (!ext->use_map) {
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/* RFC6824 requires a DSS mapping with specific values
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* if DATA_FIN is set but no data payload is mapped
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*/
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ext->data_fin = 1;
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ext->use_map = 1;
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ext->dsn64 = 1;
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ext->data_seq = subflow->data_fin_tx_seq;
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ext->subflow_seq = 0;
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ext->data_len = 1;
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} else if (ext->data_seq + ext->data_len == subflow->data_fin_tx_seq) {
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/* If there's an existing DSS mapping and it is the
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* final mapping, DATA_FIN consumes 1 additional byte of
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* mapping space.
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*/
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ext->data_fin = 1;
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ext->data_len++;
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}
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}
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static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
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unsigned int *size,
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unsigned int remaining,
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struct mptcp_out_options *opts)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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unsigned int dss_size = 0;
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struct mptcp_ext *mpext;
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struct mptcp_sock *msk;
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unsigned int ack_size;
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bool ret = false;
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u8 tcp_fin;
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if (skb) {
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mpext = mptcp_get_ext(skb);
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tcp_fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
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} else {
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mpext = NULL;
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tcp_fin = 0;
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}
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if (!skb || (mpext && mpext->use_map) || tcp_fin) {
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unsigned int map_size;
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map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
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remaining -= map_size;
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dss_size = map_size;
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if (mpext)
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opts->ext_copy = *mpext;
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if (skb && tcp_fin && subflow->data_fin_tx_enable)
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mptcp_write_data_fin(subflow, &opts->ext_copy);
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ret = true;
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}
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/* passive sockets msk will set the 'can_ack' after accept(), even
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* if the first subflow may have the already the remote key handy
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*/
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opts->ext_copy.use_ack = 0;
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msk = mptcp_sk(subflow->conn);
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if (!READ_ONCE(msk->can_ack)) {
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*size = ALIGN(dss_size, 4);
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return ret;
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}
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ack_size = TCPOLEN_MPTCP_DSS_ACK64;
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/* Add kind/length/subtype/flag overhead if mapping is not populated */
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if (dss_size == 0)
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ack_size += TCPOLEN_MPTCP_DSS_BASE;
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dss_size += ack_size;
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opts->ext_copy.data_ack = msk->ack_seq;
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opts->ext_copy.ack64 = 1;
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opts->ext_copy.use_ack = 1;
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*size = ALIGN(dss_size, 4);
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return true;
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}
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bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
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unsigned int *size, unsigned int remaining,
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struct mptcp_out_options *opts)
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{
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unsigned int opt_size = 0;
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bool ret = false;
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if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
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ret = true;
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else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
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opts))
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ret = true;
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/* we reserved enough space for the above options, and exceeding the
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* TCP option space would be fatal
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*/
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if (WARN_ON_ONCE(opt_size > remaining))
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return false;
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*size += opt_size;
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remaining -= opt_size;
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return ret;
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}
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bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
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struct mptcp_out_options *opts)
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{
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struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
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if (subflow_req->mp_capable) {
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opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
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opts->sndr_key = subflow_req->local_key;
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*size = TCPOLEN_MPTCP_MPC_SYNACK;
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pr_debug("subflow_req=%p, local_key=%llu",
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subflow_req, subflow_req->local_key);
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return true;
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}
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return false;
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}
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static bool check_fully_established(struct mptcp_subflow_context *subflow,
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struct sk_buff *skb,
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struct mptcp_options_received *mp_opt)
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{
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/* here we can process OoO, in-window pkts, only in-sequence 4th ack
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* are relevant
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*/
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if (likely(subflow->fully_established ||
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TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1))
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return true;
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if (mp_opt->use_ack)
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subflow->fully_established = 1;
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if (subflow->can_ack)
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return true;
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/* If the first established packet does not contain MP_CAPABLE + data
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* then fallback to TCP
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*/
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if (!mp_opt->mp_capable) {
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subflow->mp_capable = 0;
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tcp_sk(mptcp_subflow_tcp_sock(subflow))->is_mptcp = 0;
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return false;
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}
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subflow->remote_key = mp_opt->sndr_key;
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subflow->can_ack = 1;
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return true;
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}
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void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
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struct tcp_options_received *opt_rx)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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struct mptcp_options_received *mp_opt;
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struct mptcp_ext *mpext;
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mp_opt = &opt_rx->mptcp;
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if (!check_fully_established(subflow, skb, mp_opt))
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return;
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if (!mp_opt->dss)
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return;
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mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
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if (!mpext)
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return;
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memset(mpext, 0, sizeof(*mpext));
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if (mp_opt->use_map) {
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if (mp_opt->mpc_map) {
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/* this is an MP_CAPABLE carrying MPTCP data
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* we know this map the first chunk of data
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*/
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mptcp_crypto_key_sha(subflow->remote_key, NULL,
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&mpext->data_seq);
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mpext->data_seq++;
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mpext->subflow_seq = 1;
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mpext->dsn64 = 1;
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mpext->mpc_map = 1;
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} else {
|
|
mpext->data_seq = mp_opt->data_seq;
|
|
mpext->subflow_seq = mp_opt->subflow_seq;
|
|
mpext->dsn64 = mp_opt->dsn64;
|
|
}
|
|
mpext->data_len = mp_opt->data_len;
|
|
mpext->use_map = 1;
|
|
}
|
|
|
|
if (mp_opt->use_ack) {
|
|
mpext->data_ack = mp_opt->data_ack;
|
|
mpext->use_ack = 1;
|
|
mpext->ack64 = mp_opt->ack64;
|
|
}
|
|
|
|
mpext->data_fin = mp_opt->data_fin;
|
|
}
|
|
|
|
void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
|
|
{
|
|
if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
|
|
OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
|
|
u8 len;
|
|
|
|
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->ext_copy.data_len)
|
|
len = TCPOLEN_MPTCP_MPC_ACK_DATA;
|
|
else
|
|
len = TCPOLEN_MPTCP_MPC_ACK;
|
|
|
|
*ptr++ = htonl((TCPOPT_MPTCP << 24) | (len << 16) |
|
|
(MPTCPOPT_MP_CAPABLE << 12) |
|
|
(MPTCP_SUPPORTED_VERSION << 8) |
|
|
MPTCP_CAP_HMAC_SHA256);
|
|
|
|
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->ext_copy.data_len)
|
|
goto mp_capable_done;
|
|
|
|
put_unaligned_be32(opts->ext_copy.data_len << 16 |
|
|
TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
|
|
ptr += 1;
|
|
}
|
|
|
|
mp_capable_done:
|
|
if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
|
|
struct mptcp_ext *mpext = &opts->ext_copy;
|
|
u8 len = TCPOLEN_MPTCP_DSS_BASE;
|
|
u8 flags = 0;
|
|
|
|
if (mpext->use_ack) {
|
|
len += TCPOLEN_MPTCP_DSS_ACK64;
|
|
flags = MPTCP_DSS_HAS_ACK | MPTCP_DSS_ACK64;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
*ptr++ = htonl((TCPOPT_MPTCP << 24) |
|
|
(len << 16) |
|
|
(MPTCPOPT_DSS << 12) |
|
|
(flags));
|
|
|
|
if (mpext->use_ack) {
|
|
put_unaligned_be64(mpext->data_ack, ptr);
|
|
ptr += 2;
|
|
}
|
|
|
|
if (mpext->use_map) {
|
|
put_unaligned_be64(mpext->data_seq, ptr);
|
|
ptr += 2;
|
|
put_unaligned_be32(mpext->subflow_seq, ptr);
|
|
ptr += 1;
|
|
put_unaligned_be32(mpext->data_len << 16 |
|
|
TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
|
|
}
|
|
}
|
|
}
|