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-rw-r--r--net/mptcp/subflow.c860
1 files changed, 860 insertions, 0 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
new file mode 100644
index 000000000000..1662e1178949
--- /dev/null
+++ b/net/mptcp/subflow.c
@@ -0,0 +1,860 @@
+// 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 <linux/module.h>
+#include <linux/netdevice.h>
+#include <net/sock.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/protocol.h>
+#include <net/tcp.h>
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+#include <net/ip6_route.h>
+#endif
+#include <net/mptcp.h>
+#include "protocol.h"
+
+static int subflow_rebuild_header(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ int err = 0;
+
+ if (subflow->request_mptcp && !subflow->token) {
+ pr_debug("subflow=%p", sk);
+ err = mptcp_token_new_connect(sk);
+ }
+
+ if (err)
+ return err;
+
+ return subflow->icsk_af_ops->rebuild_header(sk);
+}
+
+static void subflow_req_destructor(struct request_sock *req)
+{
+ struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+
+ pr_debug("subflow_req=%p", subflow_req);
+
+ if (subflow_req->mp_capable)
+ mptcp_token_destroy_request(subflow_req->token);
+ tcp_request_sock_ops.destructor(req);
+}
+
+static void subflow_init_req(struct request_sock *req,
+ const struct sock *sk_listener,
+ struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
+ struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+ struct tcp_options_received rx_opt;
+
+ pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
+
+ memset(&rx_opt.mptcp, 0, sizeof(rx_opt.mptcp));
+ mptcp_get_options(skb, &rx_opt);
+
+ subflow_req->mp_capable = 0;
+ subflow_req->remote_key_valid = 0;
+
+#ifdef CONFIG_TCP_MD5SIG
+ /* no MPTCP if MD5SIG is enabled on this socket or we may run out of
+ * TCP option space.
+ */
+ if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info))
+ return;
+#endif
+
+ if (rx_opt.mptcp.mp_capable && listener->request_mptcp) {
+ int err;
+
+ err = mptcp_token_new_request(req);
+ if (err == 0)
+ subflow_req->mp_capable = 1;
+
+ subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
+ }
+}
+
+static void subflow_v4_init_req(struct request_sock *req,
+ const struct sock *sk_listener,
+ struct sk_buff *skb)
+{
+ tcp_rsk(req)->is_mptcp = 1;
+
+ tcp_request_sock_ipv4_ops.init_req(req, sk_listener, skb);
+
+ subflow_init_req(req, sk_listener, skb);
+}
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static void subflow_v6_init_req(struct request_sock *req,
+ const struct sock *sk_listener,
+ struct sk_buff *skb)
+{
+ tcp_rsk(req)->is_mptcp = 1;
+
+ tcp_request_sock_ipv6_ops.init_req(req, sk_listener, skb);
+
+ subflow_init_req(req, sk_listener, skb);
+}
+#endif
+
+static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
+
+ if (subflow->conn && !subflow->conn_finished) {
+ pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk),
+ subflow->remote_key);
+ mptcp_finish_connect(sk);
+ subflow->conn_finished = 1;
+
+ if (skb) {
+ pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq);
+ subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
+ }
+ }
+}
+
+static struct request_sock_ops subflow_request_sock_ops;
+static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
+
+static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ pr_debug("subflow=%p", subflow);
+
+ /* Never answer to SYNs sent to broadcast or multicast */
+ if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+ goto drop;
+
+ return tcp_conn_request(&subflow_request_sock_ops,
+ &subflow_request_sock_ipv4_ops,
+ sk, skb);
+drop:
+ tcp_listendrop(sk);
+ return 0;
+}
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
+static struct inet_connection_sock_af_ops subflow_v6_specific;
+static struct inet_connection_sock_af_ops subflow_v6m_specific;
+
+static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+
+ pr_debug("subflow=%p", subflow);
+
+ if (skb->protocol == htons(ETH_P_IP))
+ return subflow_v4_conn_request(sk, skb);
+
+ if (!ipv6_unicast_destination(skb))
+ goto drop;
+
+ return tcp_conn_request(&subflow_request_sock_ops,
+ &subflow_request_sock_ipv6_ops, sk, skb);
+
+drop:
+ tcp_listendrop(sk);
+ return 0; /* don't send reset */
+}
+#endif
+
+static struct sock *subflow_syn_recv_sock(const struct sock *sk,
+ struct sk_buff *skb,
+ struct request_sock *req,
+ struct dst_entry *dst,
+ struct request_sock *req_unhash,
+ bool *own_req)
+{
+ struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
+ struct mptcp_subflow_request_sock *subflow_req;
+ struct tcp_options_received opt_rx;
+ struct sock *child;
+
+ pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
+
+ /* if the sk is MP_CAPABLE, we try to fetch the client key */
+ subflow_req = mptcp_subflow_rsk(req);
+ if (subflow_req->mp_capable) {
+ if (TCP_SKB_CB(skb)->seq != subflow_req->ssn_offset + 1) {
+ /* here we can receive and accept an in-window,
+ * out-of-order pkt, which will not carry the MP_CAPABLE
+ * opt even on mptcp enabled paths
+ */
+ goto create_child;
+ }
+
+ opt_rx.mptcp.mp_capable = 0;
+ mptcp_get_options(skb, &opt_rx);
+ if (opt_rx.mptcp.mp_capable) {
+ subflow_req->remote_key = opt_rx.mptcp.sndr_key;
+ subflow_req->remote_key_valid = 1;
+ } else {
+ subflow_req->mp_capable = 0;
+ }
+ }
+
+create_child:
+ child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
+ req_unhash, own_req);
+
+ if (child && *own_req) {
+ struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
+
+ /* we have null ctx on TCP fallback, not fatal on MPC
+ * handshake
+ */
+ if (!ctx)
+ return child;
+
+ if (ctx->mp_capable) {
+ if (mptcp_token_new_accept(ctx->token))
+ goto close_child;
+ }
+ }
+
+ return child;
+
+close_child:
+ pr_debug("closing child socket");
+ tcp_send_active_reset(child, GFP_ATOMIC);
+ inet_csk_prepare_forced_close(child);
+ tcp_done(child);
+ return NULL;
+}
+
+static struct inet_connection_sock_af_ops subflow_specific;
+
+enum mapping_status {
+ MAPPING_OK,
+ MAPPING_INVALID,
+ MAPPING_EMPTY,
+ MAPPING_DATA_FIN
+};
+
+static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq)
+{
+ if ((u32)seq == (u32)old_seq)
+ return old_seq;
+
+ /* Assume map covers data not mapped yet. */
+ return seq | ((old_seq + old_data_len + 1) & GENMASK_ULL(63, 32));
+}
+
+static void warn_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
+{
+ WARN_ONCE(1, "Bad mapping: ssn=%d map_seq=%d map_data_len=%d",
+ ssn, subflow->map_subflow_seq, subflow->map_data_len);
+}
+
+static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ unsigned int skb_consumed;
+
+ skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
+ if (WARN_ON_ONCE(skb_consumed >= skb->len))
+ return true;
+
+ return skb->len - skb_consumed <= subflow->map_data_len -
+ mptcp_subflow_get_map_offset(subflow);
+}
+
+static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
+
+ if (unlikely(before(ssn, subflow->map_subflow_seq))) {
+ /* Mapping covers data later in the subflow stream,
+ * currently unsupported.
+ */
+ warn_bad_map(subflow, ssn);
+ return false;
+ }
+ if (unlikely(!before(ssn, subflow->map_subflow_seq +
+ subflow->map_data_len))) {
+ /* Mapping does covers past subflow data, invalid */
+ warn_bad_map(subflow, ssn + skb->len);
+ return false;
+ }
+ return true;
+}
+
+static enum mapping_status get_mapping_status(struct sock *ssk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ struct mptcp_ext *mpext;
+ struct sk_buff *skb;
+ u16 data_len;
+ u64 map_seq;
+
+ skb = skb_peek(&ssk->sk_receive_queue);
+ if (!skb)
+ return MAPPING_EMPTY;
+
+ mpext = mptcp_get_ext(skb);
+ if (!mpext || !mpext->use_map) {
+ if (!subflow->map_valid && !skb->len) {
+ /* the TCP stack deliver 0 len FIN pkt to the receive
+ * queue, that is the only 0len pkts ever expected here,
+ * and we can admit no mapping only for 0 len pkts
+ */
+ if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
+ WARN_ONCE(1, "0len seq %d:%d flags %x",
+ TCP_SKB_CB(skb)->seq,
+ TCP_SKB_CB(skb)->end_seq,
+ TCP_SKB_CB(skb)->tcp_flags);
+ sk_eat_skb(ssk, skb);
+ return MAPPING_EMPTY;
+ }
+
+ if (!subflow->map_valid)
+ return MAPPING_INVALID;
+
+ goto validate_seq;
+ }
+
+ pr_debug("seq=%llu is64=%d ssn=%u data_len=%u data_fin=%d",
+ mpext->data_seq, mpext->dsn64, mpext->subflow_seq,
+ mpext->data_len, mpext->data_fin);
+
+ data_len = mpext->data_len;
+ if (data_len == 0) {
+ pr_err("Infinite mapping not handled");
+ return MAPPING_INVALID;
+ }
+
+ if (mpext->data_fin == 1) {
+ if (data_len == 1) {
+ pr_debug("DATA_FIN with no payload");
+ if (subflow->map_valid) {
+ /* A DATA_FIN might arrive in a DSS
+ * option before the previous mapping
+ * has been fully consumed. Continue
+ * handling the existing mapping.
+ */
+ skb_ext_del(skb, SKB_EXT_MPTCP);
+ return MAPPING_OK;
+ } else {
+ return MAPPING_DATA_FIN;
+ }
+ }
+
+ /* Adjust for DATA_FIN using 1 byte of sequence space */
+ data_len--;
+ }
+
+ if (!mpext->dsn64) {
+ map_seq = expand_seq(subflow->map_seq, subflow->map_data_len,
+ mpext->data_seq);
+ pr_debug("expanded seq=%llu", subflow->map_seq);
+ } else {
+ map_seq = mpext->data_seq;
+ }
+
+ if (subflow->map_valid) {
+ /* Allow replacing only with an identical map */
+ if (subflow->map_seq == map_seq &&
+ subflow->map_subflow_seq == mpext->subflow_seq &&
+ subflow->map_data_len == data_len) {
+ skb_ext_del(skb, SKB_EXT_MPTCP);
+ return MAPPING_OK;
+ }
+
+ /* If this skb data are fully covered by the current mapping,
+ * the new map would need caching, which is not supported
+ */
+ if (skb_is_fully_mapped(ssk, skb))
+ return MAPPING_INVALID;
+
+ /* will validate the next map after consuming the current one */
+ return MAPPING_OK;
+ }
+
+ subflow->map_seq = map_seq;
+ subflow->map_subflow_seq = mpext->subflow_seq;
+ subflow->map_data_len = data_len;
+ subflow->map_valid = 1;
+ subflow->mpc_map = mpext->mpc_map;
+ pr_debug("new map seq=%llu subflow_seq=%u data_len=%u",
+ subflow->map_seq, subflow->map_subflow_seq,
+ subflow->map_data_len);
+
+validate_seq:
+ /* we revalidate valid mapping on new skb, because we must ensure
+ * the current skb is completely covered by the available mapping
+ */
+ if (!validate_mapping(ssk, skb))
+ return MAPPING_INVALID;
+
+ skb_ext_del(skb, SKB_EXT_MPTCP);
+ return MAPPING_OK;
+}
+
+static bool subflow_check_data_avail(struct sock *ssk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ enum mapping_status status;
+ struct mptcp_sock *msk;
+ struct sk_buff *skb;
+
+ pr_debug("msk=%p ssk=%p data_avail=%d skb=%p", subflow->conn, ssk,
+ subflow->data_avail, skb_peek(&ssk->sk_receive_queue));
+ if (subflow->data_avail)
+ return true;
+
+ if (!subflow->conn)
+ return false;
+
+ msk = mptcp_sk(subflow->conn);
+ for (;;) {
+ u32 map_remaining;
+ size_t delta;
+ u64 ack_seq;
+ u64 old_ack;
+
+ status = get_mapping_status(ssk);
+ pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
+ if (status == MAPPING_INVALID) {
+ ssk->sk_err = EBADMSG;
+ goto fatal;
+ }
+
+ if (status != MAPPING_OK)
+ return false;
+
+ skb = skb_peek(&ssk->sk_receive_queue);
+ if (WARN_ON_ONCE(!skb))
+ return false;
+
+ /* if msk lacks the remote key, this subflow must provide an
+ * MP_CAPABLE-based mapping
+ */
+ if (unlikely(!READ_ONCE(msk->can_ack))) {
+ if (!subflow->mpc_map) {
+ ssk->sk_err = EBADMSG;
+ goto fatal;
+ }
+ WRITE_ONCE(msk->remote_key, subflow->remote_key);
+ WRITE_ONCE(msk->ack_seq, subflow->map_seq);
+ WRITE_ONCE(msk->can_ack, true);
+ }
+
+ old_ack = READ_ONCE(msk->ack_seq);
+ ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
+ pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
+ ack_seq);
+ if (ack_seq == old_ack)
+ break;
+
+ /* only accept in-sequence mapping. Old values are spurious
+ * retransmission; we can hit "future" values on active backup
+ * subflow switch, we relay on retransmissions to get
+ * in-sequence data.
+ * Cuncurrent subflows support will require subflow data
+ * reordering
+ */
+ map_remaining = subflow->map_data_len -
+ mptcp_subflow_get_map_offset(subflow);
+ if (before64(ack_seq, old_ack))
+ delta = min_t(size_t, old_ack - ack_seq, map_remaining);
+ else
+ delta = min_t(size_t, ack_seq - old_ack, map_remaining);
+
+ /* discard mapped data */
+ pr_debug("discarding %zu bytes, current map len=%d", delta,
+ map_remaining);
+ if (delta) {
+ struct mptcp_read_arg arg = {
+ .msg = NULL,
+ };
+ read_descriptor_t desc = {
+ .count = delta,
+ .arg.data = &arg,
+ };
+ int ret;
+
+ ret = tcp_read_sock(ssk, &desc, mptcp_read_actor);
+ if (ret < 0) {
+ ssk->sk_err = -ret;
+ goto fatal;
+ }
+ if (ret < delta)
+ return false;
+ if (delta == map_remaining)
+ subflow->map_valid = 0;
+ }
+ }
+ return true;
+
+fatal:
+ /* fatal protocol error, close the socket */
+ /* This barrier is coupled with smp_rmb() in tcp_poll() */
+ smp_wmb();
+ ssk->sk_error_report(ssk);
+ tcp_set_state(ssk, TCP_CLOSE);
+ tcp_send_active_reset(ssk, GFP_ATOMIC);
+ return false;
+}
+
+bool mptcp_subflow_data_available(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sk_buff *skb;
+
+ /* check if current mapping is still valid */
+ if (subflow->map_valid &&
+ mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
+ subflow->map_valid = 0;
+ subflow->data_avail = 0;
+
+ pr_debug("Done with mapping: seq=%u data_len=%u",
+ subflow->map_subflow_seq,
+ subflow->map_data_len);
+ }
+
+ if (!subflow_check_data_avail(sk)) {
+ subflow->data_avail = 0;
+ return false;
+ }
+
+ skb = skb_peek(&sk->sk_receive_queue);
+ subflow->data_avail = skb &&
+ before(tcp_sk(sk)->copied_seq, TCP_SKB_CB(skb)->end_seq);
+ return subflow->data_avail;
+}
+
+static void subflow_data_ready(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sock *parent = subflow->conn;
+
+ if (!parent || !subflow->mp_capable) {
+ subflow->tcp_data_ready(sk);
+
+ if (parent)
+ parent->sk_data_ready(parent);
+ return;
+ }
+
+ if (mptcp_subflow_data_available(sk)) {
+ set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags);
+
+ parent->sk_data_ready(parent);
+ }
+}
+
+static void subflow_write_space(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sock *parent = subflow->conn;
+
+ sk_stream_write_space(sk);
+ if (parent && sk_stream_is_writeable(sk)) {
+ set_bit(MPTCP_SEND_SPACE, &mptcp_sk(parent)->flags);
+ smp_mb__after_atomic();
+ /* set SEND_SPACE before sk_stream_write_space clears NOSPACE */
+ sk_stream_write_space(parent);
+ }
+}
+
+static struct inet_connection_sock_af_ops *
+subflow_default_af_ops(struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ if (sk->sk_family == AF_INET6)
+ return &subflow_v6_specific;
+#endif
+ return &subflow_specific;
+}
+
+void mptcp_handle_ipv6_mapped(struct sock *sk, bool mapped)
+{
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct inet_connection_sock_af_ops *target;
+
+ target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
+
+ pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d",
+ subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
+
+ if (likely(icsk->icsk_af_ops == target))
+ return;
+
+ subflow->icsk_af_ops = icsk->icsk_af_ops;
+ icsk->icsk_af_ops = target;
+#endif
+}
+
+int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
+{
+ struct mptcp_subflow_context *subflow;
+ struct net *net = sock_net(sk);
+ struct socket *sf;
+ int err;
+
+ err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
+ &sf);
+ if (err)
+ return err;
+
+ lock_sock(sf->sk);
+
+ /* kernel sockets do not by default acquire net ref, but TCP timer
+ * needs it.
+ */
+ sf->sk->sk_net_refcnt = 1;
+ get_net(net);
+ this_cpu_add(*net->core.sock_inuse, 1);
+ err = tcp_set_ulp(sf->sk, "mptcp");
+ release_sock(sf->sk);
+
+ if (err)
+ return err;
+
+ subflow = mptcp_subflow_ctx(sf->sk);
+ pr_debug("subflow=%p", subflow);
+
+ *new_sock = sf;
+ sock_hold(sk);
+ subflow->conn = sk;
+
+ return 0;
+}
+
+static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
+ gfp_t priority)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct mptcp_subflow_context *ctx;
+
+ ctx = kzalloc(sizeof(*ctx), priority);
+ if (!ctx)
+ return NULL;
+
+ rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
+ INIT_LIST_HEAD(&ctx->node);
+
+ pr_debug("subflow=%p", ctx);
+
+ ctx->tcp_sock = sk;
+
+ return ctx;
+}
+
+static void __subflow_state_change(struct sock *sk)
+{
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (skwq_has_sleeper(wq))
+ wake_up_interruptible_all(&wq->wait);
+ rcu_read_unlock();
+}
+
+static bool subflow_is_done(const struct sock *sk)
+{
+ return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
+}
+
+static void subflow_state_change(struct sock *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sock *parent = READ_ONCE(subflow->conn);
+
+ __subflow_state_change(sk);
+
+ /* as recvmsg() does not acquire the subflow socket for ssk selection
+ * a fin packet carrying a DSS can be unnoticed if we don't trigger
+ * the data available machinery here.
+ */
+ if (parent && subflow->mp_capable && mptcp_subflow_data_available(sk)) {
+ set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags);
+
+ parent->sk_data_ready(parent);
+ }
+
+ if (parent && !(parent->sk_shutdown & RCV_SHUTDOWN) &&
+ !subflow->rx_eof && subflow_is_done(sk)) {
+ subflow->rx_eof = 1;
+ parent->sk_shutdown |= RCV_SHUTDOWN;
+ __subflow_state_change(parent);
+ }
+}
+
+static int subflow_ulp_init(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct mptcp_subflow_context *ctx;
+ struct tcp_sock *tp = tcp_sk(sk);
+ int err = 0;
+
+ /* disallow attaching ULP to a socket unless it has been
+ * created with sock_create_kern()
+ */
+ if (!sk->sk_kern_sock) {
+ err = -EOPNOTSUPP;
+ goto out;
+ }
+
+ ctx = subflow_create_ctx(sk, GFP_KERNEL);
+ if (!ctx) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ pr_debug("subflow=%p, family=%d", ctx, sk->sk_family);
+
+ tp->is_mptcp = 1;
+ ctx->icsk_af_ops = icsk->icsk_af_ops;
+ icsk->icsk_af_ops = subflow_default_af_ops(sk);
+ ctx->tcp_data_ready = sk->sk_data_ready;
+ ctx->tcp_state_change = sk->sk_state_change;
+ ctx->tcp_write_space = sk->sk_write_space;
+ sk->sk_data_ready = subflow_data_ready;
+ sk->sk_write_space = subflow_write_space;
+ sk->sk_state_change = subflow_state_change;
+out:
+ return err;
+}
+
+static void subflow_ulp_release(struct sock *sk)
+{
+ struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk);
+
+ if (!ctx)
+ return;
+
+ if (ctx->conn)
+ sock_put(ctx->conn);
+
+ kfree_rcu(ctx, rcu);
+}
+
+static void subflow_ulp_fallback(struct sock *sk,
+ struct mptcp_subflow_context *old_ctx)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ mptcp_subflow_tcp_fallback(sk, old_ctx);
+ icsk->icsk_ulp_ops = NULL;
+ rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
+ tcp_sk(sk)->is_mptcp = 0;
+}
+
+static void subflow_ulp_clone(const struct request_sock *req,
+ struct sock *newsk,
+ const gfp_t priority)
+{
+ struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
+ struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
+ struct mptcp_subflow_context *new_ctx;
+
+ if (!subflow_req->mp_capable) {
+ subflow_ulp_fallback(newsk, old_ctx);
+ return;
+ }
+
+ new_ctx = subflow_create_ctx(newsk, priority);
+ if (!new_ctx) {
+ subflow_ulp_fallback(newsk, old_ctx);
+ return;
+ }
+
+ /* see comments in subflow_syn_recv_sock(), MPTCP connection is fully
+ * established only after we receive the remote key
+ */
+ new_ctx->conn_finished = 1;
+ new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
+ new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
+ new_ctx->tcp_state_change = old_ctx->tcp_state_change;
+ new_ctx->tcp_write_space = old_ctx->tcp_write_space;
+ new_ctx->mp_capable = 1;
+ new_ctx->fourth_ack = subflow_req->remote_key_valid;
+ new_ctx->can_ack = subflow_req->remote_key_valid;
+ new_ctx->remote_key = subflow_req->remote_key;
+ new_ctx->local_key = subflow_req->local_key;
+ new_ctx->token = subflow_req->token;
+ new_ctx->ssn_offset = subflow_req->ssn_offset;
+ new_ctx->idsn = subflow_req->idsn;
+}
+
+static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
+ .name = "mptcp",
+ .owner = THIS_MODULE,
+ .init = subflow_ulp_init,
+ .release = subflow_ulp_release,
+ .clone = subflow_ulp_clone,
+};
+
+static int subflow_ops_init(struct request_sock_ops *subflow_ops)
+{
+ subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
+ subflow_ops->slab_name = "request_sock_subflow";
+
+ subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
+ subflow_ops->obj_size, 0,
+ SLAB_ACCOUNT |
+ SLAB_TYPESAFE_BY_RCU,
+ NULL);
+ if (!subflow_ops->slab)
+ return -ENOMEM;
+
+ subflow_ops->destructor = subflow_req_destructor;
+
+ return 0;
+}
+
+void mptcp_subflow_init(void)
+{
+ subflow_request_sock_ops = tcp_request_sock_ops;
+ if (subflow_ops_init(&subflow_request_sock_ops) != 0)
+ panic("MPTCP: failed to init subflow request sock ops\n");
+
+ subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
+ subflow_request_sock_ipv4_ops.init_req = subflow_v4_init_req;
+
+ subflow_specific = ipv4_specific;
+ subflow_specific.conn_request = subflow_v4_conn_request;
+ subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
+ subflow_specific.sk_rx_dst_set = subflow_finish_connect;
+ subflow_specific.rebuild_header = subflow_rebuild_header;
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
+ subflow_request_sock_ipv6_ops.init_req = subflow_v6_init_req;
+
+ subflow_v6_specific = ipv6_specific;
+ subflow_v6_specific.conn_request = subflow_v6_conn_request;
+ subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
+ subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
+ subflow_v6_specific.rebuild_header = subflow_rebuild_header;
+
+ subflow_v6m_specific = subflow_v6_specific;
+ subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
+ subflow_v6m_specific.send_check = ipv4_specific.send_check;
+ subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
+ subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
+ subflow_v6m_specific.net_frag_header_len = 0;
+#endif
+
+ if (tcp_register_ulp(&subflow_ulp_ops) != 0)
+ panic("MPTCP: failed to register subflows to ULP\n");
+}