diff options
Diffstat (limited to 'net/mptcp/protocol.c')
| -rw-r--r-- | net/mptcp/protocol.c | 2893 |
1 files changed, 2893 insertions, 0 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c new file mode 100644 index 000000000..72d944e6a --- /dev/null +++ b/net/mptcp/protocol.c @@ -0,0 +1,2893 @@ +// 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 <linux/sched/signal.h> +#include <linux/atomic.h> +#include <net/sock.h> +#include <net/inet_common.h> +#include <net/inet_hashtables.h> +#include <net/protocol.h> +#include <net/tcp.h> +#include <net/tcp_states.h> +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +#include <net/transp_v6.h> +#endif +#include <net/mptcp.h> +#include "protocol.h" +#include "mib.h" + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +struct mptcp6_sock { + struct mptcp_sock msk; + struct ipv6_pinfo np; +}; +#endif + +struct mptcp_skb_cb { + u64 map_seq; + u64 end_seq; + u32 offset; +}; + +#define MPTCP_SKB_CB(__skb) ((struct mptcp_skb_cb *)&((__skb)->cb[0])) + +static struct percpu_counter mptcp_sockets_allocated; + +/* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not + * completed yet or has failed, return the subflow socket. + * Otherwise return NULL. + */ +static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk) +{ + if (!msk->subflow || READ_ONCE(msk->can_ack)) + return NULL; + + return msk->subflow; +} + +static bool mptcp_is_tcpsk(struct sock *sk) +{ + struct socket *sock = sk->sk_socket; + + if (unlikely(sk->sk_prot == &tcp_prot)) { + /* we are being invoked after mptcp_accept() has + * accepted a non-mp-capable flow: sk is a tcp_sk, + * not an mptcp one. + * + * Hand the socket over to tcp so all further socket ops + * bypass mptcp. + */ + sock->ops = &inet_stream_ops; + return true; +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + } else if (unlikely(sk->sk_prot == &tcpv6_prot)) { + sock->ops = &inet6_stream_ops; + return true; +#endif + } + + return false; +} + +static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk) +{ + sock_owned_by_me((const struct sock *)msk); + + if (likely(!__mptcp_check_fallback(msk))) + return NULL; + + return msk->first; +} + +static int __mptcp_socket_create(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk = (struct sock *)msk; + struct socket *ssock; + int err; + + err = mptcp_subflow_create_socket(sk, &ssock); + if (err) + return err; + + msk->first = ssock->sk; + msk->subflow = ssock; + subflow = mptcp_subflow_ctx(ssock->sk); + list_add(&subflow->node, &msk->conn_list); + subflow->request_mptcp = 1; + + /* accept() will wait on first subflow sk_wq, and we always wakes up + * via msk->sk_socket + */ + RCU_INIT_POINTER(msk->first->sk_wq, &sk->sk_socket->wq); + + return 0; +} + +static void mptcp_drop(struct sock *sk, struct sk_buff *skb) +{ + sk_drops_add(sk, skb); + __kfree_skb(skb); +} + +static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, + struct sk_buff *from) +{ + bool fragstolen; + int delta; + + if (MPTCP_SKB_CB(from)->offset || + !skb_try_coalesce(to, from, &fragstolen, &delta)) + return false; + + pr_debug("colesced seq %llx into %llx new len %d new end seq %llx", + MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq, + to->len, MPTCP_SKB_CB(from)->end_seq); + MPTCP_SKB_CB(to)->end_seq = MPTCP_SKB_CB(from)->end_seq; + kfree_skb_partial(from, fragstolen); + atomic_add(delta, &sk->sk_rmem_alloc); + sk_mem_charge(sk, delta); + return true; +} + +static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to, + struct sk_buff *from) +{ + if (MPTCP_SKB_CB(from)->map_seq != MPTCP_SKB_CB(to)->end_seq) + return false; + + return mptcp_try_coalesce((struct sock *)msk, to, from); +} + +/* "inspired" by tcp_data_queue_ofo(), main differences: + * - use mptcp seqs + * - don't cope with sacks + */ +static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb) +{ + struct sock *sk = (struct sock *)msk; + struct rb_node **p, *parent; + u64 seq, end_seq, max_seq; + struct sk_buff *skb1; + int space; + + seq = MPTCP_SKB_CB(skb)->map_seq; + end_seq = MPTCP_SKB_CB(skb)->end_seq; + space = tcp_space(sk); + max_seq = space > 0 ? space + msk->ack_seq : msk->ack_seq; + + pr_debug("msk=%p seq=%llx limit=%llx empty=%d", msk, seq, max_seq, + RB_EMPTY_ROOT(&msk->out_of_order_queue)); + if (after64(seq, max_seq)) { + /* out of window */ + mptcp_drop(sk, skb); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_NODSSWINDOW); + return; + } + + p = &msk->out_of_order_queue.rb_node; + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUE); + if (RB_EMPTY_ROOT(&msk->out_of_order_queue)) { + rb_link_node(&skb->rbnode, NULL, p); + rb_insert_color(&skb->rbnode, &msk->out_of_order_queue); + msk->ooo_last_skb = skb; + goto end; + } + + /* with 2 subflows, adding at end of ooo queue is quite likely + * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup. + */ + if (mptcp_ooo_try_coalesce(msk, msk->ooo_last_skb, skb)) { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL); + return; + } + + /* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */ + if (!before64(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL); + parent = &msk->ooo_last_skb->rbnode; + p = &parent->rb_right; + goto insert; + } + + /* Find place to insert this segment. Handle overlaps on the way. */ + parent = NULL; + while (*p) { + parent = *p; + skb1 = rb_to_skb(parent); + if (before64(seq, MPTCP_SKB_CB(skb1)->map_seq)) { + p = &parent->rb_left; + continue; + } + if (before64(seq, MPTCP_SKB_CB(skb1)->end_seq)) { + if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) { + /* All the bits are present. Drop. */ + mptcp_drop(sk, skb); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); + return; + } + if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) { + /* partial overlap: + * | skb | + * | skb1 | + * continue traversing + */ + } else { + /* skb's seq == skb1's seq and skb covers skb1. + * Replace skb1 with skb. + */ + rb_replace_node(&skb1->rbnode, &skb->rbnode, + &msk->out_of_order_queue); + mptcp_drop(sk, skb1); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); + goto merge_right; + } + } else if (mptcp_ooo_try_coalesce(msk, skb1, skb)) { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE); + return; + } + p = &parent->rb_right; + } + +insert: + /* Insert segment into RB tree. */ + rb_link_node(&skb->rbnode, parent, p); + rb_insert_color(&skb->rbnode, &msk->out_of_order_queue); + +merge_right: + /* Remove other segments covered by skb. */ + while ((skb1 = skb_rb_next(skb)) != NULL) { + if (before64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) + break; + rb_erase(&skb1->rbnode, &msk->out_of_order_queue); + mptcp_drop(sk, skb1); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); + } + /* If there is no skb after us, we are the last_skb ! */ + if (!skb1) + msk->ooo_last_skb = skb; + +end: + skb_condense(skb); + skb_set_owner_r(skb, sk); +} + +static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk, + struct sk_buff *skb, unsigned int offset, + size_t copy_len) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); + struct sock *sk = (struct sock *)msk; + struct sk_buff *tail; + + __skb_unlink(skb, &ssk->sk_receive_queue); + + skb_ext_reset(skb); + skb_orphan(skb); + + /* try to fetch required memory from subflow */ + if (!sk_rmem_schedule(sk, skb, skb->truesize)) { + int amount = sk_mem_pages(skb->truesize) << SK_MEM_QUANTUM_SHIFT; + + if (ssk->sk_forward_alloc < amount) + goto drop; + + ssk->sk_forward_alloc -= amount; + sk->sk_forward_alloc += amount; + } + + /* the skb map_seq accounts for the skb offset: + * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq + * value + */ + MPTCP_SKB_CB(skb)->map_seq = mptcp_subflow_get_mapped_dsn(subflow); + MPTCP_SKB_CB(skb)->end_seq = MPTCP_SKB_CB(skb)->map_seq + copy_len; + MPTCP_SKB_CB(skb)->offset = offset; + + if (MPTCP_SKB_CB(skb)->map_seq == msk->ack_seq) { + /* in sequence */ + WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len); + tail = skb_peek_tail(&sk->sk_receive_queue); + if (tail && mptcp_try_coalesce(sk, tail, skb)) + return true; + + skb_set_owner_r(skb, sk); + __skb_queue_tail(&sk->sk_receive_queue, skb); + return true; + } else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) { + mptcp_data_queue_ofo(msk, skb); + return false; + } + + /* old data, keep it simple and drop the whole pkt, sender + * will retransmit as needed, if needed. + */ + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); +drop: + mptcp_drop(sk, skb); + return false; +} + +static void mptcp_stop_timer(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + sk_stop_timer(sk, &icsk->icsk_retransmit_timer); + mptcp_sk(sk)->timer_ival = 0; +} + +static void mptcp_check_data_fin_ack(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (__mptcp_check_fallback(msk)) + return; + + /* Look for an acknowledged DATA_FIN */ + if (((1 << sk->sk_state) & + (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) && + msk->write_seq == atomic64_read(&msk->snd_una)) { + mptcp_stop_timer(sk); + + WRITE_ONCE(msk->snd_data_fin_enable, 0); + + switch (sk->sk_state) { + case TCP_FIN_WAIT1: + inet_sk_state_store(sk, TCP_FIN_WAIT2); + sk->sk_state_change(sk); + break; + case TCP_CLOSING: + case TCP_LAST_ACK: + inet_sk_state_store(sk, TCP_CLOSE); + sk->sk_state_change(sk); + break; + } + + if (sk->sk_shutdown == SHUTDOWN_MASK || + sk->sk_state == TCP_CLOSE) + sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); + else + sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); + } +} + +static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (READ_ONCE(msk->rcv_data_fin) && + ((1 << sk->sk_state) & + (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) { + u64 rcv_data_fin_seq = READ_ONCE(msk->rcv_data_fin_seq); + + if (msk->ack_seq == rcv_data_fin_seq) { + if (seq) + *seq = rcv_data_fin_seq; + + return true; + } + } + + return false; +} + +static void mptcp_set_timeout(const struct sock *sk, const struct sock *ssk) +{ + long tout = ssk && inet_csk(ssk)->icsk_pending ? + inet_csk(ssk)->icsk_timeout - jiffies : 0; + + if (tout <= 0) + tout = mptcp_sk(sk)->timer_ival; + mptcp_sk(sk)->timer_ival = tout > 0 ? tout : TCP_RTO_MIN; +} + +static void mptcp_check_data_fin(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + u64 rcv_data_fin_seq; + + if (__mptcp_check_fallback(msk) || !msk->first) + return; + + /* Need to ack a DATA_FIN received from a peer while this side + * of the connection is in ESTABLISHED, FIN_WAIT1, or FIN_WAIT2. + * msk->rcv_data_fin was set when parsing the incoming options + * at the subflow level and the msk lock was not held, so this + * is the first opportunity to act on the DATA_FIN and change + * the msk state. + * + * If we are caught up to the sequence number of the incoming + * DATA_FIN, send the DATA_ACK now and do state transition. If + * not caught up, do nothing and let the recv code send DATA_ACK + * when catching up. + */ + + if (mptcp_pending_data_fin(sk, &rcv_data_fin_seq)) { + struct mptcp_subflow_context *subflow; + + WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1); + WRITE_ONCE(msk->rcv_data_fin, 0); + + sk->sk_shutdown |= RCV_SHUTDOWN; + smp_mb__before_atomic(); /* SHUTDOWN must be visible first */ + set_bit(MPTCP_DATA_READY, &msk->flags); + + switch (sk->sk_state) { + case TCP_ESTABLISHED: + inet_sk_state_store(sk, TCP_CLOSE_WAIT); + break; + case TCP_FIN_WAIT1: + inet_sk_state_store(sk, TCP_CLOSING); + break; + case TCP_FIN_WAIT2: + inet_sk_state_store(sk, TCP_CLOSE); + // @@ Close subflows now? + break; + default: + /* Other states not expected */ + WARN_ON_ONCE(1); + break; + } + + mptcp_set_timeout(sk, NULL); + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + lock_sock(ssk); + tcp_send_ack(ssk); + release_sock(ssk); + } + + sk->sk_state_change(sk); + + if (sk->sk_shutdown == SHUTDOWN_MASK || + sk->sk_state == TCP_CLOSE) + sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); + else + sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); + } +} + +static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, + struct sock *ssk, + unsigned int *bytes) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); + struct sock *sk = (struct sock *)msk; + unsigned int moved = 0; + bool more_data_avail; + struct tcp_sock *tp; + u32 old_copied_seq; + bool done = false; + + pr_debug("msk=%p ssk=%p", msk, ssk); + tp = tcp_sk(ssk); + old_copied_seq = tp->copied_seq; + do { + u32 map_remaining, offset; + u32 seq = tp->copied_seq; + struct sk_buff *skb; + bool fin; + + /* try to move as much data as available */ + map_remaining = subflow->map_data_len - + mptcp_subflow_get_map_offset(subflow); + + skb = skb_peek(&ssk->sk_receive_queue); + if (!skb) { + /* if no data is found, a racing workqueue/recvmsg + * already processed the new data, stop here or we + * can enter an infinite loop + */ + if (!moved) + done = true; + break; + } + + if (__mptcp_check_fallback(msk)) { + /* if we are running under the workqueue, TCP could have + * collapsed skbs between dummy map creation and now + * be sure to adjust the size + */ + map_remaining = skb->len; + subflow->map_data_len = skb->len; + } + + offset = seq - TCP_SKB_CB(skb)->seq; + fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN; + if (fin) { + done = true; + seq++; + } + + if (offset < skb->len) { + size_t len = skb->len - offset; + + if (tp->urg_data) + done = true; + + if (__mptcp_move_skb(msk, ssk, skb, offset, len)) + moved += len; + seq += len; + + if (WARN_ON_ONCE(map_remaining < len)) + break; + } else { + WARN_ON_ONCE(!fin); + sk_eat_skb(ssk, skb); + done = true; + } + + WRITE_ONCE(tp->copied_seq, seq); + more_data_avail = mptcp_subflow_data_available(ssk); + + if (atomic_read(&sk->sk_rmem_alloc) > READ_ONCE(sk->sk_rcvbuf)) { + done = true; + break; + } + } while (more_data_avail); + + *bytes += moved; + if (tp->copied_seq != old_copied_seq) + tcp_cleanup_rbuf(ssk, 1); + + return done; +} + +static bool mptcp_ofo_queue(struct mptcp_sock *msk) +{ + struct sock *sk = (struct sock *)msk; + struct sk_buff *skb, *tail; + bool moved = false; + struct rb_node *p; + u64 end_seq; + + p = rb_first(&msk->out_of_order_queue); + pr_debug("msk=%p empty=%d", msk, RB_EMPTY_ROOT(&msk->out_of_order_queue)); + while (p) { + skb = rb_to_skb(p); + if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) + break; + + p = rb_next(p); + rb_erase(&skb->rbnode, &msk->out_of_order_queue); + + if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq, + msk->ack_seq))) { + mptcp_drop(sk, skb); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); + continue; + } + + end_seq = MPTCP_SKB_CB(skb)->end_seq; + tail = skb_peek_tail(&sk->sk_receive_queue); + if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) { + int delta = msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq; + + /* skip overlapping data, if any */ + pr_debug("uncoalesced seq=%llx ack seq=%llx delta=%d", + MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq, + delta); + MPTCP_SKB_CB(skb)->offset += delta; + __skb_queue_tail(&sk->sk_receive_queue, skb); + } + msk->ack_seq = end_seq; + moved = true; + } + return moved; +} + +/* In most cases we will be able to lock the mptcp socket. If its already + * owned, we need to defer to the work queue to avoid ABBA deadlock. + */ +static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk) +{ + struct sock *sk = (struct sock *)msk; + unsigned int moved = 0; + + if (READ_ONCE(sk->sk_lock.owned)) + return false; + + if (unlikely(!spin_trylock_bh(&sk->sk_lock.slock))) + return false; + + /* must re-check after taking the lock */ + if (!READ_ONCE(sk->sk_lock.owned)) { + __mptcp_move_skbs_from_subflow(msk, ssk, &moved); + mptcp_ofo_queue(msk); + + /* If the moves have caught up with the DATA_FIN sequence number + * it's time to ack the DATA_FIN and change socket state, but + * this is not a good place to change state. Let the workqueue + * do it. + */ + if (mptcp_pending_data_fin(sk, NULL) && + schedule_work(&msk->work)) + sock_hold(sk); + } + + spin_unlock_bh(&sk->sk_lock.slock); + + return moved > 0; +} + +void mptcp_data_ready(struct sock *sk, struct sock *ssk) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); + struct mptcp_sock *msk = mptcp_sk(sk); + bool wake; + + /* move_skbs_to_msk below can legitly clear the data_avail flag, + * but we will need later to properly woke the reader, cache its + * value + */ + wake = subflow->data_avail == MPTCP_SUBFLOW_DATA_AVAIL; + if (wake) + set_bit(MPTCP_DATA_READY, &msk->flags); + + if (atomic_read(&sk->sk_rmem_alloc) < READ_ONCE(sk->sk_rcvbuf) && + move_skbs_to_msk(msk, ssk)) + goto wake; + + /* don't schedule if mptcp sk is (still) over limit */ + if (atomic_read(&sk->sk_rmem_alloc) > READ_ONCE(sk->sk_rcvbuf)) + goto wake; + + /* mptcp socket is owned, release_cb should retry */ + if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, + &sk->sk_tsq_flags)) { + sock_hold(sk); + + /* need to try again, its possible release_cb() has already + * been called after the test_and_set_bit() above. + */ + move_skbs_to_msk(msk, ssk); + } +wake: + if (wake) + sk->sk_data_ready(sk); +} + +static void __mptcp_flush_join_list(struct mptcp_sock *msk) +{ + if (likely(list_empty(&msk->join_list))) + return; + + spin_lock_bh(&msk->join_list_lock); + list_splice_tail_init(&msk->join_list, &msk->conn_list); + spin_unlock_bh(&msk->join_list_lock); +} + +static bool mptcp_timer_pending(struct sock *sk) +{ + return timer_pending(&inet_csk(sk)->icsk_retransmit_timer); +} + +static void mptcp_reset_timer(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + unsigned long tout; + + /* should never be called with mptcp level timer cleared */ + tout = READ_ONCE(mptcp_sk(sk)->timer_ival); + if (WARN_ON_ONCE(!tout)) + tout = TCP_RTO_MIN; + sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout); +} + +void mptcp_data_acked(struct sock *sk) +{ + mptcp_reset_timer(sk); + + if ((!test_bit(MPTCP_SEND_SPACE, &mptcp_sk(sk)->flags) || + (inet_sk_state_load(sk) != TCP_ESTABLISHED)) && + schedule_work(&mptcp_sk(sk)->work)) + sock_hold(sk); +} + +void mptcp_subflow_eof(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (!test_and_set_bit(MPTCP_WORK_EOF, &msk->flags) && + schedule_work(&msk->work)) + sock_hold(sk); +} + +static void mptcp_check_for_eof(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk = (struct sock *)msk; + int receivers = 0; + + mptcp_for_each_subflow(msk, subflow) + receivers += !subflow->rx_eof; + + if (!receivers && !(sk->sk_shutdown & RCV_SHUTDOWN)) { + /* hopefully temporary hack: propagate shutdown status + * to msk, when all subflows agree on it + */ + sk->sk_shutdown |= RCV_SHUTDOWN; + + smp_mb__before_atomic(); /* SHUTDOWN must be visible first */ + set_bit(MPTCP_DATA_READY, &msk->flags); + sk->sk_data_ready(sk); + } +} + +static bool mptcp_ext_cache_refill(struct mptcp_sock *msk) +{ + const struct sock *sk = (const struct sock *)msk; + + if (!msk->cached_ext) + msk->cached_ext = __skb_ext_alloc(sk->sk_allocation); + + return !!msk->cached_ext; +} + +static struct sock *mptcp_subflow_recv_lookup(const struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk = (struct sock *)msk; + + sock_owned_by_me(sk); + + mptcp_for_each_subflow(msk, subflow) { + if (subflow->data_avail) + return mptcp_subflow_tcp_sock(subflow); + } + + return NULL; +} + +static bool mptcp_skb_can_collapse_to(u64 write_seq, + const struct sk_buff *skb, + const struct mptcp_ext *mpext) +{ + if (!tcp_skb_can_collapse_to(skb)) + return false; + + /* can collapse only if MPTCP level sequence is in order */ + return mpext && mpext->data_seq + mpext->data_len == write_seq; +} + +/* we can append data to the given data frag if: + * - there is space available in the backing page_frag + * - the data frag tail matches the current page_frag free offset + * - the data frag end sequence number matches the current write seq + */ +static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk, + const struct page_frag *pfrag, + const struct mptcp_data_frag *df) +{ + return df && pfrag->page == df->page && + pfrag->offset == (df->offset + df->data_len) && + df->data_seq + df->data_len == msk->write_seq; +} + +static void dfrag_uncharge(struct sock *sk, int len) +{ + sk_mem_uncharge(sk, len); + sk_wmem_queued_add(sk, -len); +} + +static void dfrag_clear(struct sock *sk, struct mptcp_data_frag *dfrag) +{ + int len = dfrag->data_len + dfrag->overhead; + + list_del(&dfrag->list); + dfrag_uncharge(sk, len); + put_page(dfrag->page); +} + +static bool mptcp_is_writeable(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + + if (!sk_stream_is_writeable((struct sock *)msk)) + return false; + + mptcp_for_each_subflow(msk, subflow) { + if (sk_stream_is_writeable(subflow->tcp_sock)) + return true; + } + return false; +} + +static void mptcp_clean_una(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct mptcp_data_frag *dtmp, *dfrag; + bool cleaned = false; + u64 snd_una; + + /* on fallback we just need to ignore snd_una, as this is really + * plain TCP + */ + if (__mptcp_check_fallback(msk)) + atomic64_set(&msk->snd_una, msk->write_seq); + snd_una = atomic64_read(&msk->snd_una); + + list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) { + if (after64(dfrag->data_seq + dfrag->data_len, snd_una)) + break; + + dfrag_clear(sk, dfrag); + cleaned = true; + } + + dfrag = mptcp_rtx_head(sk); + if (dfrag && after64(snd_una, dfrag->data_seq)) { + u64 delta = snd_una - dfrag->data_seq; + + if (WARN_ON_ONCE(delta > dfrag->data_len)) + goto out; + + dfrag->data_seq += delta; + dfrag->offset += delta; + dfrag->data_len -= delta; + + dfrag_uncharge(sk, delta); + cleaned = true; + } + +out: + if (cleaned) { + sk_mem_reclaim_partial(sk); + + /* Only wake up writers if a subflow is ready */ + if (mptcp_is_writeable(msk)) { + set_bit(MPTCP_SEND_SPACE, &mptcp_sk(sk)->flags); + smp_mb__after_atomic(); + + /* set SEND_SPACE before sk_stream_write_space clears + * NOSPACE + */ + sk_stream_write_space(sk); + } + } +} + +/* ensure we get enough memory for the frag hdr, beyond some minimal amount of + * data + */ +static bool mptcp_page_frag_refill(struct sock *sk, struct page_frag *pfrag) +{ + if (likely(skb_page_frag_refill(32U + sizeof(struct mptcp_data_frag), + pfrag, sk->sk_allocation))) + return true; + + sk->sk_prot->enter_memory_pressure(sk); + sk_stream_moderate_sndbuf(sk); + return false; +} + +static struct mptcp_data_frag * +mptcp_carve_data_frag(const struct mptcp_sock *msk, struct page_frag *pfrag, + int orig_offset) +{ + int offset = ALIGN(orig_offset, sizeof(long)); + struct mptcp_data_frag *dfrag; + + dfrag = (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset); + dfrag->data_len = 0; + dfrag->data_seq = msk->write_seq; + dfrag->overhead = offset - orig_offset + sizeof(struct mptcp_data_frag); + dfrag->offset = offset + sizeof(struct mptcp_data_frag); + dfrag->page = pfrag->page; + + return dfrag; +} + +static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, + struct msghdr *msg, struct mptcp_data_frag *dfrag, + long *timeo, int *pmss_now, + int *ps_goal) +{ + int mss_now, avail_size, size_goal, offset, ret, frag_truesize = 0; + bool dfrag_collapsed, can_collapse = false; + struct mptcp_sock *msk = mptcp_sk(sk); + struct mptcp_ext *mpext = NULL; + bool retransmission = !!dfrag; + struct sk_buff *skb, *tail; + struct page_frag *pfrag; + struct page *page; + u64 *write_seq; + size_t psize; + + /* use the mptcp page cache so that we can easily move the data + * from one substream to another, but do per subflow memory accounting + * Note: pfrag is used only !retransmission, but the compiler if + * fooled into a warning if we don't init here + */ + pfrag = sk_page_frag(sk); + if (!retransmission) { + write_seq = &msk->write_seq; + page = pfrag->page; + } else { + write_seq = &dfrag->data_seq; + page = dfrag->page; + } + + /* compute copy limit */ + mss_now = tcp_send_mss(ssk, &size_goal, msg->msg_flags); + *pmss_now = mss_now; + *ps_goal = size_goal; + avail_size = size_goal; + skb = tcp_write_queue_tail(ssk); + if (skb) { + mpext = skb_ext_find(skb, SKB_EXT_MPTCP); + + /* Limit the write to the size available in the + * current skb, if any, so that we create at most a new skb. + * Explicitly tells TCP internals to avoid collapsing on later + * queue management operation, to avoid breaking the ext <-> + * SSN association set here + */ + can_collapse = (size_goal - skb->len > 0) && + mptcp_skb_can_collapse_to(*write_seq, skb, mpext); + if (!can_collapse) + TCP_SKB_CB(skb)->eor = 1; + else + avail_size = size_goal - skb->len; + } + + if (!retransmission) { + /* reuse tail pfrag, if possible, or carve a new one from the + * page allocator + */ + dfrag = mptcp_rtx_tail(sk); + offset = pfrag->offset; + dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag); + if (!dfrag_collapsed) { + dfrag = mptcp_carve_data_frag(msk, pfrag, offset); + offset = dfrag->offset; + frag_truesize = dfrag->overhead; + } + psize = min_t(size_t, pfrag->size - offset, avail_size); + + /* Copy to page */ + pr_debug("left=%zu", msg_data_left(msg)); + psize = copy_page_from_iter(pfrag->page, offset, + min_t(size_t, msg_data_left(msg), + psize), + &msg->msg_iter); + pr_debug("left=%zu", msg_data_left(msg)); + if (!psize) + return -EINVAL; + + if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) { + iov_iter_revert(&msg->msg_iter, psize); + return -ENOMEM; + } + } else { + offset = dfrag->offset; + psize = min_t(size_t, dfrag->data_len, avail_size); + } + + /* tell the TCP stack to delay the push so that we can safely + * access the skb after the sendpages call + */ + ret = do_tcp_sendpages(ssk, page, offset, psize, + msg->msg_flags | MSG_SENDPAGE_NOTLAST | MSG_DONTWAIT); + if (ret <= 0) { + if (!retransmission) + iov_iter_revert(&msg->msg_iter, psize); + return ret; + } + + frag_truesize += ret; + if (!retransmission) { + if (unlikely(ret < psize)) + iov_iter_revert(&msg->msg_iter, psize - ret); + + /* send successful, keep track of sent data for mptcp-level + * retransmission + */ + dfrag->data_len += ret; + if (!dfrag_collapsed) { + get_page(dfrag->page); + list_add_tail(&dfrag->list, &msk->rtx_queue); + sk_wmem_queued_add(sk, frag_truesize); + } else { + sk_wmem_queued_add(sk, ret); + } + + /* charge data on mptcp rtx queue to the master socket + * Note: we charge such data both to sk and ssk + */ + sk->sk_forward_alloc -= frag_truesize; + } + + /* if the tail skb extension is still the cached one, collapsing + * really happened. Note: we can't check for 'same skb' as the sk_buff + * hdr on tail can be transmitted, freed and re-allocated by the + * do_tcp_sendpages() call + */ + tail = tcp_write_queue_tail(ssk); + if (mpext && tail && mpext == skb_ext_find(tail, SKB_EXT_MPTCP)) { + WARN_ON_ONCE(!can_collapse); + mpext->data_len += ret; + goto out; + } + + skb = tcp_write_queue_tail(ssk); + mpext = __skb_ext_set(skb, SKB_EXT_MPTCP, msk->cached_ext); + msk->cached_ext = NULL; + + memset(mpext, 0, sizeof(*mpext)); + mpext->data_seq = *write_seq; + mpext->subflow_seq = mptcp_subflow_ctx(ssk)->rel_write_seq; + mpext->data_len = ret; + mpext->use_map = 1; + mpext->dsn64 = 1; + + pr_debug("data_seq=%llu subflow_seq=%u data_len=%u dsn64=%d", + mpext->data_seq, mpext->subflow_seq, mpext->data_len, + mpext->dsn64); + +out: + if (!retransmission) + pfrag->offset += frag_truesize; + WRITE_ONCE(*write_seq, *write_seq + ret); + mptcp_subflow_ctx(ssk)->rel_write_seq += ret; + + return ret; +} + +static void mptcp_nospace(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + + clear_bit(MPTCP_SEND_SPACE, &msk->flags); + smp_mb__after_atomic(); /* msk->flags is changed by write_space cb */ + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + struct socket *sock = READ_ONCE(ssk->sk_socket); + + /* enables ssk->write_space() callbacks */ + if (sock) + set_bit(SOCK_NOSPACE, &sock->flags); + } +} + +static bool mptcp_subflow_active(struct mptcp_subflow_context *subflow) +{ + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + /* can't send if JOIN hasn't completed yet (i.e. is usable for mptcp) */ + if (subflow->request_join && !subflow->fully_established) + return false; + + /* only send if our side has not closed yet */ + return ((1 << ssk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)); +} + +#define MPTCP_SEND_BURST_SIZE ((1 << 16) - \ + sizeof(struct tcphdr) - \ + MAX_TCP_OPTION_SPACE - \ + sizeof(struct ipv6hdr) - \ + sizeof(struct frag_hdr)) + +struct subflow_send_info { + struct sock *ssk; + u64 ratio; +}; + +static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk, + u32 *sndbuf) +{ + struct subflow_send_info send_info[2]; + struct mptcp_subflow_context *subflow; + int i, nr_active = 0; + struct sock *ssk; + u64 ratio; + u32 pace; + + sock_owned_by_me((struct sock *)msk); + + *sndbuf = 0; + if (!mptcp_ext_cache_refill(msk)) + return NULL; + + if (__mptcp_check_fallback(msk)) { + if (!msk->first) + return NULL; + *sndbuf = msk->first->sk_sndbuf; + return sk_stream_memory_free(msk->first) ? msk->first : NULL; + } + + /* re-use last subflow, if the burst allow that */ + if (msk->last_snd && msk->snd_burst > 0 && + sk_stream_memory_free(msk->last_snd) && + mptcp_subflow_active(mptcp_subflow_ctx(msk->last_snd))) { + mptcp_for_each_subflow(msk, subflow) { + ssk = mptcp_subflow_tcp_sock(subflow); + *sndbuf = max(tcp_sk(ssk)->snd_wnd, *sndbuf); + } + return msk->last_snd; + } + + /* pick the subflow with the lower wmem/wspace ratio */ + for (i = 0; i < 2; ++i) { + send_info[i].ssk = NULL; + send_info[i].ratio = -1; + } + mptcp_for_each_subflow(msk, subflow) { + ssk = mptcp_subflow_tcp_sock(subflow); + if (!mptcp_subflow_active(subflow)) + continue; + + nr_active += !subflow->backup; + *sndbuf = max(tcp_sk(ssk)->snd_wnd, *sndbuf); + if (!sk_stream_memory_free(subflow->tcp_sock)) + continue; + + pace = READ_ONCE(ssk->sk_pacing_rate); + if (!pace) + continue; + + ratio = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32, + pace); + if (ratio < send_info[subflow->backup].ratio) { + send_info[subflow->backup].ssk = ssk; + send_info[subflow->backup].ratio = ratio; + } + } + + pr_debug("msk=%p nr_active=%d ssk=%p:%lld backup=%p:%lld", + msk, nr_active, send_info[0].ssk, send_info[0].ratio, + send_info[1].ssk, send_info[1].ratio); + + /* pick the best backup if no other subflow is active */ + if (!nr_active) + send_info[0].ssk = send_info[1].ssk; + + if (send_info[0].ssk) { + msk->last_snd = send_info[0].ssk; + msk->snd_burst = min_t(int, MPTCP_SEND_BURST_SIZE, + sk_stream_wspace(msk->last_snd)); + return msk->last_snd; + } + return NULL; +} + +static void ssk_check_wmem(struct mptcp_sock *msk) +{ + if (unlikely(!mptcp_is_writeable(msk))) + mptcp_nospace(msk); +} + +static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +{ + int mss_now = 0, size_goal = 0, ret = 0; + struct mptcp_sock *msk = mptcp_sk(sk); + struct page_frag *pfrag; + size_t copied = 0; + struct sock *ssk; + u32 sndbuf; + bool tx_ok; + long timeo; + + if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL)) + return -EOPNOTSUPP; + + lock_sock(sk); + + timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); + + if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) { + ret = sk_stream_wait_connect(sk, &timeo); + if (ret) + goto out; + } + + pfrag = sk_page_frag(sk); +restart: + mptcp_clean_una(sk); + + if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) { + ret = -EPIPE; + goto out; + } + + __mptcp_flush_join_list(msk); + ssk = mptcp_subflow_get_send(msk, &sndbuf); + while (!sk_stream_memory_free(sk) || + !ssk || + !mptcp_page_frag_refill(ssk, pfrag)) { + if (ssk) { + /* make sure retransmit timer is + * running before we wait for memory. + * + * The retransmit timer might be needed + * to make the peer send an up-to-date + * MPTCP Ack. + */ + mptcp_set_timeout(sk, ssk); + if (!mptcp_timer_pending(sk)) + mptcp_reset_timer(sk); + } + + mptcp_nospace(msk); + ret = sk_stream_wait_memory(sk, &timeo); + if (ret) + goto out; + + mptcp_clean_una(sk); + + ssk = mptcp_subflow_get_send(msk, &sndbuf); + if (list_empty(&msk->conn_list)) { + ret = -ENOTCONN; + goto out; + } + } + + /* do auto tuning */ + if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK) && + sndbuf > READ_ONCE(sk->sk_sndbuf)) + WRITE_ONCE(sk->sk_sndbuf, sndbuf); + + pr_debug("conn_list->subflow=%p", ssk); + + lock_sock(ssk); + tx_ok = msg_data_left(msg); + while (tx_ok) { + ret = mptcp_sendmsg_frag(sk, ssk, msg, NULL, &timeo, &mss_now, + &size_goal); + if (ret < 0) { + if (ret == -EAGAIN && timeo > 0) { + mptcp_set_timeout(sk, ssk); + release_sock(ssk); + goto restart; + } + break; + } + + /* burst can be negative, we will try move to the next subflow + * at selection time, if possible. + */ + msk->snd_burst -= ret; + copied += ret; + + tx_ok = msg_data_left(msg); + if (!tx_ok) + break; + + if (!sk_stream_memory_free(ssk) || + !mptcp_page_frag_refill(ssk, pfrag) || + !mptcp_ext_cache_refill(msk)) { + tcp_push(ssk, msg->msg_flags, mss_now, + tcp_sk(ssk)->nonagle, size_goal); + mptcp_set_timeout(sk, ssk); + release_sock(ssk); + goto restart; + } + + /* memory is charged to mptcp level socket as well, i.e. + * if msg is very large, mptcp socket may run out of buffer + * space. mptcp_clean_una() will release data that has + * been acked at mptcp level in the mean time, so there is + * a good chance we can continue sending data right away. + * + * Normally, when the tcp subflow can accept more data, then + * so can the MPTCP socket. However, we need to cope with + * peers that might lag behind in their MPTCP-level + * acknowledgements, i.e. data might have been acked at + * tcp level only. So, we must also check the MPTCP socket + * limits before we send more data. + */ + if (unlikely(!sk_stream_memory_free(sk))) { + tcp_push(ssk, msg->msg_flags, mss_now, + tcp_sk(ssk)->nonagle, size_goal); + mptcp_clean_una(sk); + if (!sk_stream_memory_free(sk)) { + /* can't send more for now, need to wait for + * MPTCP-level ACKs from peer. + * + * Wakeup will happen via mptcp_clean_una(). + */ + mptcp_set_timeout(sk, ssk); + release_sock(ssk); + goto restart; + } + } + } + + mptcp_set_timeout(sk, ssk); + if (copied) { + tcp_push(ssk, msg->msg_flags, mss_now, tcp_sk(ssk)->nonagle, + size_goal); + + /* start the timer, if it's not pending */ + if (!mptcp_timer_pending(sk)) + mptcp_reset_timer(sk); + } + + release_sock(ssk); +out: + ssk_check_wmem(msk); + release_sock(sk); + return copied ? : ret; +} + +static void mptcp_wait_data(struct sock *sk, long *timeo) +{ + DEFINE_WAIT_FUNC(wait, woken_wake_function); + struct mptcp_sock *msk = mptcp_sk(sk); + + add_wait_queue(sk_sleep(sk), &wait); + sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); + + sk_wait_event(sk, timeo, + test_and_clear_bit(MPTCP_DATA_READY, &msk->flags), &wait); + + sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); + remove_wait_queue(sk_sleep(sk), &wait); +} + +static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk, + struct msghdr *msg, + size_t len) +{ + struct sock *sk = (struct sock *)msk; + struct sk_buff *skb; + int copied = 0; + + while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) { + u32 offset = MPTCP_SKB_CB(skb)->offset; + u32 data_len = skb->len - offset; + u32 count = min_t(size_t, len - copied, data_len); + int err; + + err = skb_copy_datagram_msg(skb, offset, msg, count); + if (unlikely(err < 0)) { + if (!copied) + return err; + break; + } + + copied += count; + + if (count < data_len) { + MPTCP_SKB_CB(skb)->offset += count; + break; + } + + __skb_unlink(skb, &sk->sk_receive_queue); + __kfree_skb(skb); + + if (copied >= len) + break; + } + + return copied; +} + +/* receive buffer autotuning. See tcp_rcv_space_adjust for more information. + * + * Only difference: Use highest rtt estimate of the subflows in use. + */ +static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk = (struct sock *)msk; + u32 time, advmss = 1; + u64 rtt_us, mstamp; + + sock_owned_by_me(sk); + + if (copied <= 0) + return; + + msk->rcvq_space.copied += copied; + + mstamp = div_u64(tcp_clock_ns(), NSEC_PER_USEC); + time = tcp_stamp_us_delta(mstamp, msk->rcvq_space.time); + + rtt_us = msk->rcvq_space.rtt_us; + if (rtt_us && time < (rtt_us >> 3)) + return; + + rtt_us = 0; + mptcp_for_each_subflow(msk, subflow) { + const struct tcp_sock *tp; + u64 sf_rtt_us; + u32 sf_advmss; + + tp = tcp_sk(mptcp_subflow_tcp_sock(subflow)); + + sf_rtt_us = READ_ONCE(tp->rcv_rtt_est.rtt_us); + sf_advmss = READ_ONCE(tp->advmss); + + rtt_us = max(sf_rtt_us, rtt_us); + advmss = max(sf_advmss, advmss); + } + + msk->rcvq_space.rtt_us = rtt_us; + if (time < (rtt_us >> 3) || rtt_us == 0) + return; + + if (msk->rcvq_space.copied <= msk->rcvq_space.space) + goto new_measure; + + if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) && + !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) { + int rcvmem, rcvbuf; + u64 rcvwin, grow; + + rcvwin = ((u64)msk->rcvq_space.copied << 1) + 16 * advmss; + + grow = rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space); + + do_div(grow, msk->rcvq_space.space); + rcvwin += (grow << 1); + + rcvmem = SKB_TRUESIZE(advmss + MAX_TCP_HEADER); + while (tcp_win_from_space(sk, rcvmem) < advmss) + rcvmem += 128; + + do_div(rcvwin, advmss); + rcvbuf = min_t(u64, rcvwin * rcvmem, + READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); + + if (rcvbuf > sk->sk_rcvbuf) { + u32 window_clamp; + + window_clamp = tcp_win_from_space(sk, rcvbuf); + WRITE_ONCE(sk->sk_rcvbuf, rcvbuf); + + /* Make subflows follow along. If we do not do this, we + * get drops at subflow level if skbs can't be moved to + * the mptcp rx queue fast enough (announced rcv_win can + * exceed ssk->sk_rcvbuf). + */ + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk; + bool slow; + + ssk = mptcp_subflow_tcp_sock(subflow); + slow = lock_sock_fast(ssk); + WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf); + tcp_sk(ssk)->window_clamp = window_clamp; + tcp_cleanup_rbuf(ssk, 1); + unlock_sock_fast(ssk, slow); + } + } + } + + msk->rcvq_space.space = msk->rcvq_space.copied; +new_measure: + msk->rcvq_space.copied = 0; + msk->rcvq_space.time = mstamp; +} + +static bool __mptcp_move_skbs(struct mptcp_sock *msk) +{ + unsigned int moved = 0; + bool done; + + /* avoid looping forever below on racing close */ + if (((struct sock *)msk)->sk_state == TCP_CLOSE) + return false; + + __mptcp_flush_join_list(msk); + do { + struct sock *ssk = mptcp_subflow_recv_lookup(msk); + + if (!ssk) + break; + + lock_sock(ssk); + done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved); + release_sock(ssk); + } while (!done); + + if (mptcp_ofo_queue(msk) || moved > 0) { + mptcp_check_data_fin((struct sock *)msk); + return true; + } + return false; +} + +static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, + int nonblock, int flags, int *addr_len) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + int copied = 0; + int target; + long timeo; + + if (msg->msg_flags & ~(MSG_WAITALL | MSG_DONTWAIT)) + return -EOPNOTSUPP; + + lock_sock(sk); + timeo = sock_rcvtimeo(sk, nonblock); + + len = min_t(size_t, len, INT_MAX); + target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); + __mptcp_flush_join_list(msk); + + while (len > (size_t)copied) { + int bytes_read; + + bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied); + if (unlikely(bytes_read < 0)) { + if (!copied) + copied = bytes_read; + goto out_err; + } + + copied += bytes_read; + + if (skb_queue_empty(&sk->sk_receive_queue) && + __mptcp_move_skbs(msk)) + continue; + + /* only the master socket status is relevant here. The exit + * conditions mirror closely tcp_recvmsg() + */ + if (copied >= target) + break; + + if (copied) { + if (sk->sk_err || + sk->sk_state == TCP_CLOSE || + (sk->sk_shutdown & RCV_SHUTDOWN) || + !timeo || + signal_pending(current)) + break; + } else { + if (sk->sk_err) { + copied = sock_error(sk); + break; + } + + if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags)) + mptcp_check_for_eof(msk); + + if (sk->sk_shutdown & RCV_SHUTDOWN) + break; + + if (sk->sk_state == TCP_CLOSE) { + copied = -ENOTCONN; + break; + } + + if (!timeo) { + copied = -EAGAIN; + break; + } + + if (signal_pending(current)) { + copied = sock_intr_errno(timeo); + break; + } + } + + pr_debug("block timeout %ld", timeo); + mptcp_wait_data(sk, &timeo); + } + + if (skb_queue_empty(&sk->sk_receive_queue)) { + /* entire backlog drained, clear DATA_READY. */ + clear_bit(MPTCP_DATA_READY, &msk->flags); + + /* .. race-breaker: ssk might have gotten new data + * after last __mptcp_move_skbs() returned false. + */ + if (unlikely(__mptcp_move_skbs(msk))) + set_bit(MPTCP_DATA_READY, &msk->flags); + } else if (unlikely(!test_bit(MPTCP_DATA_READY, &msk->flags))) { + /* data to read but mptcp_wait_data() cleared DATA_READY */ + set_bit(MPTCP_DATA_READY, &msk->flags); + } +out_err: + pr_debug("msk=%p data_ready=%d rx queue empty=%d copied=%d", + msk, test_bit(MPTCP_DATA_READY, &msk->flags), + skb_queue_empty(&sk->sk_receive_queue), copied); + mptcp_rcv_space_adjust(msk, copied); + + release_sock(sk); + return copied; +} + +static void mptcp_retransmit_handler(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (atomic64_read(&msk->snd_una) == READ_ONCE(msk->write_seq)) { + mptcp_stop_timer(sk); + } else { + set_bit(MPTCP_WORK_RTX, &msk->flags); + if (schedule_work(&msk->work)) + sock_hold(sk); + } +} + +static void mptcp_retransmit_timer(struct timer_list *t) +{ + struct inet_connection_sock *icsk = from_timer(icsk, t, + icsk_retransmit_timer); + struct sock *sk = &icsk->icsk_inet.sk; + + bh_lock_sock(sk); + if (!sock_owned_by_user(sk)) { + mptcp_retransmit_handler(sk); + } else { + /* delegate our work to tcp_release_cb() */ + if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, + &sk->sk_tsq_flags)) + sock_hold(sk); + } + bh_unlock_sock(sk); + sock_put(sk); +} + +/* Find an idle subflow. Return NULL if there is unacked data at tcp + * level. + * + * A backup subflow is returned only if that is the only kind available. + */ +static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + struct sock *backup = NULL; + + sock_owned_by_me((const struct sock *)msk); + + if (__mptcp_check_fallback(msk)) + return msk->first; + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + if (!mptcp_subflow_active(subflow)) + continue; + + /* still data outstanding at TCP level? Don't retransmit. */ + if (!tcp_write_queue_empty(ssk)) { + if (inet_csk(ssk)->icsk_ca_state >= TCP_CA_Loss) + continue; + return NULL; + } + + if (subflow->backup) { + if (!backup) + backup = ssk; + continue; + } + + return ssk; + } + + return backup; +} + +/* subflow sockets can be either outgoing (connect) or incoming + * (accept). + * + * Outgoing subflows use in-kernel sockets. + * Incoming subflows do not have their own 'struct socket' allocated, + * so we need to use tcp_close() after detaching them from the mptcp + * parent socket. + */ +void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, + struct mptcp_subflow_context *subflow, + long timeout) +{ + struct socket *sock = READ_ONCE(ssk->sk_socket); + + list_del(&subflow->node); + + if (sock && sock != sk->sk_socket) { + /* outgoing subflow */ + sock_release(sock); + } else { + /* incoming subflow */ + tcp_close(ssk, timeout); + } +} + +static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu) +{ + return 0; +} + +static void pm_work(struct mptcp_sock *msk) +{ + struct mptcp_pm_data *pm = &msk->pm; + + spin_lock_bh(&msk->pm.lock); + + pr_debug("msk=%p status=%x", msk, pm->status); + if (pm->status & BIT(MPTCP_PM_ADD_ADDR_RECEIVED)) { + pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED); + mptcp_pm_nl_add_addr_received(msk); + } + if (pm->status & BIT(MPTCP_PM_RM_ADDR_RECEIVED)) { + pm->status &= ~BIT(MPTCP_PM_RM_ADDR_RECEIVED); + mptcp_pm_nl_rm_addr_received(msk); + } + if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) { + pm->status &= ~BIT(MPTCP_PM_ESTABLISHED); + mptcp_pm_nl_fully_established(msk); + } + if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) { + pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED); + mptcp_pm_nl_subflow_established(msk); + } + + spin_unlock_bh(&msk->pm.lock); +} + +static void __mptcp_close_subflow(struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow, *tmp; + + list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + if (inet_sk_state_load(ssk) != TCP_CLOSE) + continue; + + __mptcp_close_ssk((struct sock *)msk, ssk, subflow, 0); + } +} + +static void mptcp_worker(struct work_struct *work) +{ + struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work); + struct sock *ssk, *sk = &msk->sk.icsk_inet.sk; + int orig_len, orig_offset, mss_now = 0, size_goal = 0; + struct mptcp_data_frag *dfrag; + u64 orig_write_seq; + size_t copied = 0; + struct msghdr msg = { + .msg_flags = MSG_DONTWAIT, + }; + long timeo = 0; + + lock_sock(sk); + mptcp_clean_una(sk); + mptcp_check_data_fin_ack(sk); + __mptcp_flush_join_list(msk); + if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) + __mptcp_close_subflow(msk); + + __mptcp_move_skbs(msk); + + if (msk->pm.status) + pm_work(msk); + + if (test_and_clear_bit(MPTCP_WORK_EOF, &msk->flags)) + mptcp_check_for_eof(msk); + + mptcp_check_data_fin(sk); + + if (!test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags)) + goto unlock; + + dfrag = mptcp_rtx_head(sk); + if (!dfrag) + goto unlock; + + if (!mptcp_ext_cache_refill(msk)) + goto reset_unlock; + + ssk = mptcp_subflow_get_retrans(msk); + if (!ssk) + goto reset_unlock; + + lock_sock(ssk); + + orig_len = dfrag->data_len; + orig_offset = dfrag->offset; + orig_write_seq = dfrag->data_seq; + while (dfrag->data_len > 0) { + int ret = mptcp_sendmsg_frag(sk, ssk, &msg, dfrag, &timeo, + &mss_now, &size_goal); + if (ret < 0) + break; + + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RETRANSSEGS); + copied += ret; + dfrag->data_len -= ret; + dfrag->offset += ret; + + if (!mptcp_ext_cache_refill(msk)) + break; + } + if (copied) + tcp_push(ssk, msg.msg_flags, mss_now, tcp_sk(ssk)->nonagle, + size_goal); + + dfrag->data_seq = orig_write_seq; + dfrag->offset = orig_offset; + dfrag->data_len = orig_len; + + mptcp_set_timeout(sk, ssk); + release_sock(ssk); + +reset_unlock: + if (!mptcp_timer_pending(sk)) + mptcp_reset_timer(sk); + +unlock: + release_sock(sk); + sock_put(sk); +} + +static int __mptcp_init_sock(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + spin_lock_init(&msk->join_list_lock); + + INIT_LIST_HEAD(&msk->conn_list); + INIT_LIST_HEAD(&msk->join_list); + INIT_LIST_HEAD(&msk->rtx_queue); + __set_bit(MPTCP_SEND_SPACE, &msk->flags); + INIT_WORK(&msk->work, mptcp_worker); + msk->out_of_order_queue = RB_ROOT; + + msk->first = NULL; + inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss; + + mptcp_pm_data_init(msk); + + /* re-use the csk retrans timer for MPTCP-level retrans */ + timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0); + + return 0; +} + +static int mptcp_init_sock(struct sock *sk) +{ + struct net *net = sock_net(sk); + int ret; + + ret = __mptcp_init_sock(sk); + if (ret) + return ret; + + if (!mptcp_is_enabled(net)) + return -ENOPROTOOPT; + + if (unlikely(!net->mib.mptcp_statistics) && !mptcp_mib_alloc(net)) + return -ENOMEM; + + ret = __mptcp_socket_create(mptcp_sk(sk)); + if (ret) + return ret; + + sk_sockets_allocated_inc(sk); + sk->sk_rcvbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]); + sk->sk_sndbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]); + + return 0; +} + +static void __mptcp_clear_xmit(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct mptcp_data_frag *dtmp, *dfrag; + + sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer); + + list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) + dfrag_clear(sk, dfrag); +} + +static void mptcp_cancel_work(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (cancel_work_sync(&msk->work)) + sock_put(sk); +} + +void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how) +{ + lock_sock(ssk); + + switch (ssk->sk_state) { + case TCP_LISTEN: + if (!(how & RCV_SHUTDOWN)) + break; + fallthrough; + case TCP_SYN_SENT: + tcp_disconnect(ssk, O_NONBLOCK); + break; + default: + if (__mptcp_check_fallback(mptcp_sk(sk))) { + pr_debug("Fallback"); + ssk->sk_shutdown |= how; + tcp_shutdown(ssk, how); + } else { + pr_debug("Sending DATA_FIN on subflow %p", ssk); + mptcp_set_timeout(sk, ssk); + tcp_send_ack(ssk); + } + break; + } + + release_sock(ssk); +} + +static const unsigned char new_state[16] = { + /* current state: new state: action: */ + [0 /* (Invalid) */] = TCP_CLOSE, + [TCP_ESTABLISHED] = TCP_FIN_WAIT1 | TCP_ACTION_FIN, + [TCP_SYN_SENT] = TCP_CLOSE, + [TCP_SYN_RECV] = TCP_FIN_WAIT1 | TCP_ACTION_FIN, + [TCP_FIN_WAIT1] = TCP_FIN_WAIT1, + [TCP_FIN_WAIT2] = TCP_FIN_WAIT2, + [TCP_TIME_WAIT] = TCP_CLOSE, /* should not happen ! */ + [TCP_CLOSE] = TCP_CLOSE, + [TCP_CLOSE_WAIT] = TCP_LAST_ACK | TCP_ACTION_FIN, + [TCP_LAST_ACK] = TCP_LAST_ACK, + [TCP_LISTEN] = TCP_CLOSE, + [TCP_CLOSING] = TCP_CLOSING, + [TCP_NEW_SYN_RECV] = TCP_CLOSE, /* should not happen ! */ +}; + +static int mptcp_close_state(struct sock *sk) +{ + int next = (int)new_state[sk->sk_state]; + int ns = next & TCP_STATE_MASK; + + inet_sk_state_store(sk, ns); + + return next & TCP_ACTION_FIN; +} + +static void mptcp_close(struct sock *sk, long timeout) +{ + struct mptcp_subflow_context *subflow, *tmp; + struct mptcp_sock *msk = mptcp_sk(sk); + LIST_HEAD(conn_list); + + lock_sock(sk); + sk->sk_shutdown = SHUTDOWN_MASK; + + if (sk->sk_state == TCP_LISTEN) { + inet_sk_state_store(sk, TCP_CLOSE); + goto cleanup; + } else if (sk->sk_state == TCP_CLOSE) { + goto cleanup; + } + + if (__mptcp_check_fallback(msk)) { + goto update_state; + } else if (mptcp_close_state(sk)) { + pr_debug("Sending DATA_FIN sk=%p", sk); + WRITE_ONCE(msk->write_seq, msk->write_seq + 1); + WRITE_ONCE(msk->snd_data_fin_enable, 1); + + mptcp_for_each_subflow(msk, subflow) { + struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow); + + mptcp_subflow_shutdown(sk, tcp_sk, SHUTDOWN_MASK); + } + } + + sk_stream_wait_close(sk, timeout); + +update_state: + inet_sk_state_store(sk, TCP_CLOSE); + +cleanup: + /* be sure to always acquire the join list lock, to sync vs + * mptcp_finish_join(). + */ + spin_lock_bh(&msk->join_list_lock); + list_splice_tail_init(&msk->join_list, &msk->conn_list); + spin_unlock_bh(&msk->join_list_lock); + list_splice_init(&msk->conn_list, &conn_list); + + __mptcp_clear_xmit(sk); + + release_sock(sk); + + list_for_each_entry_safe(subflow, tmp, &conn_list, node) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + __mptcp_close_ssk(sk, ssk, subflow, timeout); + } + + mptcp_cancel_work(sk); + + __skb_queue_purge(&sk->sk_receive_queue); + + sk_common_release(sk); +} + +static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk) +{ +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + const struct ipv6_pinfo *ssk6 = inet6_sk(ssk); + struct ipv6_pinfo *msk6 = inet6_sk(msk); + + msk->sk_v6_daddr = ssk->sk_v6_daddr; + msk->sk_v6_rcv_saddr = ssk->sk_v6_rcv_saddr; + + if (msk6 && ssk6) { + msk6->saddr = ssk6->saddr; + msk6->flow_label = ssk6->flow_label; + } +#endif + + inet_sk(msk)->inet_num = inet_sk(ssk)->inet_num; + inet_sk(msk)->inet_dport = inet_sk(ssk)->inet_dport; + inet_sk(msk)->inet_sport = inet_sk(ssk)->inet_sport; + inet_sk(msk)->inet_daddr = inet_sk(ssk)->inet_daddr; + inet_sk(msk)->inet_saddr = inet_sk(ssk)->inet_saddr; + inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr; +} + +static int mptcp_disconnect(struct sock *sk, int flags) +{ + /* Should never be called. + * inet_stream_connect() calls ->disconnect, but that + * refers to the subflow socket, not the mptcp one. + */ + WARN_ON_ONCE(1); + return 0; +} + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk) +{ + unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo); + + return (struct ipv6_pinfo *)(((u8 *)sk) + offset); +} +#endif + +struct sock *mptcp_sk_clone(const struct sock *sk, + const struct mptcp_options_received *mp_opt, + struct request_sock *req) +{ + struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req); + struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC); + struct mptcp_sock *msk; + u64 ack_seq; + + if (!nsk) + return NULL; + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + if (nsk->sk_family == AF_INET6) + inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk); +#endif + + __mptcp_init_sock(nsk); + + msk = mptcp_sk(nsk); + msk->local_key = subflow_req->local_key; + msk->token = subflow_req->token; + msk->subflow = NULL; + WRITE_ONCE(msk->fully_established, false); + + msk->write_seq = subflow_req->idsn + 1; + atomic64_set(&msk->snd_una, msk->write_seq); + if (mp_opt->mp_capable) { + msk->can_ack = true; + msk->remote_key = mp_opt->sndr_key; + mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq); + ack_seq++; + WRITE_ONCE(msk->ack_seq, ack_seq); + } + + sock_reset_flag(nsk, SOCK_RCU_FREE); + /* will be fully established after successful MPC subflow creation */ + inet_sk_state_store(nsk, TCP_SYN_RECV); + + security_inet_csk_clone(nsk, req); + bh_unlock_sock(nsk); + + /* keep a single reference */ + __sock_put(nsk); + return nsk; +} + +void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk) +{ + const struct tcp_sock *tp = tcp_sk(ssk); + + msk->rcvq_space.copied = 0; + msk->rcvq_space.rtt_us = 0; + + msk->rcvq_space.time = tp->tcp_mstamp; + + /* initial rcv_space offering made to peer */ + msk->rcvq_space.space = min_t(u32, tp->rcv_wnd, + TCP_INIT_CWND * tp->advmss); + if (msk->rcvq_space.space == 0) + msk->rcvq_space.space = TCP_INIT_CWND * TCP_MSS_DEFAULT; +} + +static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, + bool kern) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct socket *listener; + struct sock *newsk; + + listener = __mptcp_nmpc_socket(msk); + if (WARN_ON_ONCE(!listener)) { + *err = -EINVAL; + return NULL; + } + + pr_debug("msk=%p, listener=%p", msk, mptcp_subflow_ctx(listener->sk)); + newsk = inet_csk_accept(listener->sk, flags, err, kern); + if (!newsk) + return NULL; + + pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk)); + if (sk_is_mptcp(newsk)) { + struct mptcp_subflow_context *subflow; + struct sock *new_mptcp_sock; + struct sock *ssk = newsk; + + subflow = mptcp_subflow_ctx(newsk); + new_mptcp_sock = subflow->conn; + + /* is_mptcp should be false if subflow->conn is missing, see + * subflow_syn_recv_sock() + */ + if (WARN_ON_ONCE(!new_mptcp_sock)) { + tcp_sk(newsk)->is_mptcp = 0; + goto out; + } + + /* acquire the 2nd reference for the owning socket */ + sock_hold(new_mptcp_sock); + + local_bh_disable(); + bh_lock_sock(new_mptcp_sock); + msk = mptcp_sk(new_mptcp_sock); + msk->first = newsk; + + newsk = new_mptcp_sock; + mptcp_copy_inaddrs(newsk, ssk); + list_add(&subflow->node, &msk->conn_list); + + mptcp_rcv_space_init(msk, ssk); + bh_unlock_sock(new_mptcp_sock); + + __MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK); + local_bh_enable(); + } else { + MPTCP_INC_STATS(sock_net(sk), + MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK); + } + +out: + newsk->sk_kern_sock = kern; + return newsk; +} + +void mptcp_destroy_common(struct mptcp_sock *msk) +{ + skb_rbtree_purge(&msk->out_of_order_queue); + mptcp_token_destroy(msk); + mptcp_pm_free_anno_list(msk); +} + +static void mptcp_destroy(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (msk->cached_ext) + __skb_ext_put(msk->cached_ext); + + mptcp_destroy_common(msk); + sk_sockets_allocated_dec(sk); +} + +static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct sock *sk = (struct sock *)msk; + struct socket *ssock; + int ret; + + switch (optname) { + case SO_REUSEPORT: + case SO_REUSEADDR: + lock_sock(sk); + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) { + release_sock(sk); + return -EINVAL; + } + + ret = sock_setsockopt(ssock, SOL_SOCKET, optname, optval, optlen); + if (ret == 0) { + if (optname == SO_REUSEPORT) + sk->sk_reuseport = ssock->sk->sk_reuseport; + else if (optname == SO_REUSEADDR) + sk->sk_reuse = ssock->sk->sk_reuse; + } + release_sock(sk); + return ret; + } + + return sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname, optval, optlen); +} + +static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct sock *sk = (struct sock *)msk; + int ret = -EOPNOTSUPP; + struct socket *ssock; + + switch (optname) { + case IPV6_V6ONLY: + lock_sock(sk); + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) { + release_sock(sk); + return -EINVAL; + } + + ret = tcp_setsockopt(ssock->sk, SOL_IPV6, optname, optval, optlen); + if (ret == 0) + sk->sk_ipv6only = ssock->sk->sk_ipv6only; + + release_sock(sk); + break; + } + + return ret; +} + +static bool mptcp_unsupported(int level, int optname) +{ + if (level == SOL_IP) { + switch (optname) { + case IP_ADD_MEMBERSHIP: + case IP_ADD_SOURCE_MEMBERSHIP: + case IP_DROP_MEMBERSHIP: + case IP_DROP_SOURCE_MEMBERSHIP: + case IP_BLOCK_SOURCE: + case IP_UNBLOCK_SOURCE: + case MCAST_JOIN_GROUP: + case MCAST_LEAVE_GROUP: + case MCAST_JOIN_SOURCE_GROUP: + case MCAST_LEAVE_SOURCE_GROUP: + case MCAST_BLOCK_SOURCE: + case MCAST_UNBLOCK_SOURCE: + case MCAST_MSFILTER: + return true; + } + return false; + } + if (level == SOL_IPV6) { + switch (optname) { + case IPV6_ADDRFORM: + case IPV6_ADD_MEMBERSHIP: + case IPV6_DROP_MEMBERSHIP: + case IPV6_JOIN_ANYCAST: + case IPV6_LEAVE_ANYCAST: + case MCAST_JOIN_GROUP: + case MCAST_LEAVE_GROUP: + case MCAST_JOIN_SOURCE_GROUP: + case MCAST_LEAVE_SOURCE_GROUP: + case MCAST_BLOCK_SOURCE: + case MCAST_UNBLOCK_SOURCE: + case MCAST_MSFILTER: + return true; + } + return false; + } + return false; +} + +static int mptcp_setsockopt(struct sock *sk, int level, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct sock *ssk; + + pr_debug("msk=%p", msk); + + if (mptcp_unsupported(level, optname)) + return -ENOPROTOOPT; + + if (level == SOL_SOCKET) + return mptcp_setsockopt_sol_socket(msk, optname, optval, optlen); + + /* @@ the meaning of setsockopt() when the socket is connected and + * there are multiple subflows is not yet defined. It is up to the + * MPTCP-level socket to configure the subflows until the subflow + * is in TCP fallback, when TCP socket options are passed through + * to the one remaining subflow. + */ + lock_sock(sk); + ssk = __mptcp_tcp_fallback(msk); + release_sock(sk); + if (ssk) + return tcp_setsockopt(ssk, level, optname, optval, optlen); + + if (level == SOL_IPV6) + return mptcp_setsockopt_v6(msk, optname, optval, optlen); + + return -EOPNOTSUPP; +} + +static int mptcp_getsockopt(struct sock *sk, int level, int optname, + char __user *optval, int __user *option) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct sock *ssk; + + pr_debug("msk=%p", msk); + + /* @@ the meaning of setsockopt() when the socket is connected and + * there are multiple subflows is not yet defined. It is up to the + * MPTCP-level socket to configure the subflows until the subflow + * is in TCP fallback, when socket options are passed through + * to the one remaining subflow. + */ + lock_sock(sk); + ssk = __mptcp_tcp_fallback(msk); + release_sock(sk); + if (ssk) + return tcp_getsockopt(ssk, level, optname, optval, option); + + return -EOPNOTSUPP; +} + +#define MPTCP_DEFERRED_ALL (TCPF_DELACK_TIMER_DEFERRED | \ + TCPF_WRITE_TIMER_DEFERRED) + +/* this is very alike tcp_release_cb() but we must handle differently a + * different set of events + */ +static void mptcp_release_cb(struct sock *sk) +{ + unsigned long flags, nflags; + + do { + flags = sk->sk_tsq_flags; + if (!(flags & MPTCP_DEFERRED_ALL)) + return; + nflags = flags & ~MPTCP_DEFERRED_ALL; + } while (cmpxchg(&sk->sk_tsq_flags, flags, nflags) != flags); + + sock_release_ownership(sk); + + if (flags & TCPF_DELACK_TIMER_DEFERRED) { + struct mptcp_sock *msk = mptcp_sk(sk); + struct sock *ssk; + + ssk = mptcp_subflow_recv_lookup(msk); + if (!ssk || !schedule_work(&msk->work)) + __sock_put(sk); + } + + if (flags & TCPF_WRITE_TIMER_DEFERRED) { + mptcp_retransmit_handler(sk); + __sock_put(sk); + } +} + +static int mptcp_hash(struct sock *sk) +{ + /* should never be called, + * we hash the TCP subflows not the master socket + */ + WARN_ON_ONCE(1); + return 0; +} + +static void mptcp_unhash(struct sock *sk) +{ + /* called from sk_common_release(), but nothing to do here */ +} + +static int mptcp_get_port(struct sock *sk, unsigned short snum) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct socket *ssock; + + ssock = __mptcp_nmpc_socket(msk); + pr_debug("msk=%p, subflow=%p", msk, ssock); + if (WARN_ON_ONCE(!ssock)) + return -EINVAL; + + return inet_csk_get_port(ssock->sk, snum); +} + +void mptcp_finish_connect(struct sock *ssk) +{ + struct mptcp_subflow_context *subflow; + struct mptcp_sock *msk; + struct sock *sk; + u64 ack_seq; + + subflow = mptcp_subflow_ctx(ssk); + sk = subflow->conn; + msk = mptcp_sk(sk); + + pr_debug("msk=%p, token=%u", sk, subflow->token); + + mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq); + ack_seq++; + subflow->map_seq = ack_seq; + subflow->map_subflow_seq = 1; + + /* the socket is not connected yet, no msk/subflow ops can access/race + * accessing the field below + */ + WRITE_ONCE(msk->remote_key, subflow->remote_key); + WRITE_ONCE(msk->local_key, subflow->local_key); + WRITE_ONCE(msk->write_seq, subflow->idsn + 1); + WRITE_ONCE(msk->ack_seq, ack_seq); + WRITE_ONCE(msk->can_ack, 1); + atomic64_set(&msk->snd_una, msk->write_seq); + + mptcp_pm_new_connection(msk, 0); + + mptcp_rcv_space_init(msk, ssk); +} + +static void mptcp_sock_graft(struct sock *sk, struct socket *parent) +{ + write_lock_bh(&sk->sk_callback_lock); + rcu_assign_pointer(sk->sk_wq, &parent->wq); + sk_set_socket(sk, parent); + sk->sk_uid = SOCK_INODE(parent)->i_uid; + write_unlock_bh(&sk->sk_callback_lock); +} + +bool mptcp_finish_join(struct sock *sk) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + struct sock *parent = (void *)msk; + struct socket *parent_sock; + bool ret; + + pr_debug("msk=%p, subflow=%p", msk, subflow); + + /* mptcp socket already closing? */ + if (!mptcp_is_fully_established(parent)) + return false; + + if (!msk->pm.server_side) + return true; + + if (!mptcp_pm_allow_new_subflow(msk)) + return false; + + /* active connections are already on conn_list, and we can't acquire + * msk lock here. + * use the join list lock as synchronization point and double-check + * msk status to avoid racing with mptcp_close() + */ + spin_lock_bh(&msk->join_list_lock); + ret = inet_sk_state_load(parent) == TCP_ESTABLISHED; + if (ret && !WARN_ON_ONCE(!list_empty(&subflow->node))) + list_add_tail(&subflow->node, &msk->join_list); + spin_unlock_bh(&msk->join_list_lock); + if (!ret) + return false; + + /* attach to msk socket only after we are sure he will deal with us + * at close time + */ + parent_sock = READ_ONCE(parent->sk_socket); + if (parent_sock && !sk->sk_socket) + mptcp_sock_graft(sk, parent_sock); + subflow->map_seq = READ_ONCE(msk->ack_seq); + return true; +} + +static bool mptcp_memory_free(const struct sock *sk, int wake) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + return wake ? test_bit(MPTCP_SEND_SPACE, &msk->flags) : true; +} + +static struct proto mptcp_prot = { + .name = "MPTCP", + .owner = THIS_MODULE, + .init = mptcp_init_sock, + .disconnect = mptcp_disconnect, + .close = mptcp_close, + .accept = mptcp_accept, + .setsockopt = mptcp_setsockopt, + .getsockopt = mptcp_getsockopt, + .shutdown = tcp_shutdown, + .destroy = mptcp_destroy, + .sendmsg = mptcp_sendmsg, + .recvmsg = mptcp_recvmsg, + .release_cb = mptcp_release_cb, + .hash = mptcp_hash, + .unhash = mptcp_unhash, + .get_port = mptcp_get_port, + .sockets_allocated = &mptcp_sockets_allocated, + .memory_allocated = &tcp_memory_allocated, + .memory_pressure = &tcp_memory_pressure, + .stream_memory_free = mptcp_memory_free, + .sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_tcp_wmem), + .sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_tcp_rmem), + .sysctl_mem = sysctl_tcp_mem, + .obj_size = sizeof(struct mptcp_sock), + .slab_flags = SLAB_TYPESAFE_BY_RCU, + .no_autobind = true, +}; + +static int mptcp_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct socket *ssock; + int err; + + lock_sock(sock->sk); + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) { + err = -EINVAL; + goto unlock; + } + + err = ssock->ops->bind(ssock, uaddr, addr_len); + if (!err) + mptcp_copy_inaddrs(sock->sk, ssock->sk); + +unlock: + release_sock(sock->sk); + return err; +} + +static void mptcp_subflow_early_fallback(struct mptcp_sock *msk, + struct mptcp_subflow_context *subflow) +{ + subflow->request_mptcp = 0; + __mptcp_do_fallback(msk); +} + +static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, + int addr_len, int flags) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct mptcp_subflow_context *subflow; + struct socket *ssock; + int err; + + lock_sock(sock->sk); + if (sock->state != SS_UNCONNECTED && msk->subflow) { + /* pending connection or invalid state, let existing subflow + * cope with that + */ + ssock = msk->subflow; + goto do_connect; + } + + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) { + err = -EINVAL; + goto unlock; + } + + mptcp_token_destroy(msk); + inet_sk_state_store(sock->sk, TCP_SYN_SENT); + subflow = mptcp_subflow_ctx(ssock->sk); +#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(ssock->sk)->md5sig_info)) + mptcp_subflow_early_fallback(msk, subflow); +#endif + if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) + mptcp_subflow_early_fallback(msk, subflow); + +do_connect: + err = ssock->ops->connect(ssock, uaddr, addr_len, flags); + sock->state = ssock->state; + + /* on successful connect, the msk state will be moved to established by + * subflow_finish_connect() + */ + if (!err || err == -EINPROGRESS) + mptcp_copy_inaddrs(sock->sk, ssock->sk); + else + inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk)); + +unlock: + release_sock(sock->sk); + return err; +} + +static int mptcp_listen(struct socket *sock, int backlog) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct socket *ssock; + int err; + + pr_debug("msk=%p", msk); + + lock_sock(sock->sk); + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) { + err = -EINVAL; + goto unlock; + } + + mptcp_token_destroy(msk); + inet_sk_state_store(sock->sk, TCP_LISTEN); + sock_set_flag(sock->sk, SOCK_RCU_FREE); + + err = ssock->ops->listen(ssock, backlog); + inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk)); + if (!err) + mptcp_copy_inaddrs(sock->sk, ssock->sk); + +unlock: + release_sock(sock->sk); + return err; +} + +static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, + int flags, bool kern) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct socket *ssock; + int err; + + pr_debug("msk=%p", msk); + + lock_sock(sock->sk); + if (sock->sk->sk_state != TCP_LISTEN) + goto unlock_fail; + + ssock = __mptcp_nmpc_socket(msk); + if (!ssock) + goto unlock_fail; + + clear_bit(MPTCP_DATA_READY, &msk->flags); + sock_hold(ssock->sk); + release_sock(sock->sk); + + err = ssock->ops->accept(sock, newsock, flags, kern); + if (err == 0 && !mptcp_is_tcpsk(newsock->sk)) { + struct mptcp_sock *msk = mptcp_sk(newsock->sk); + struct mptcp_subflow_context *subflow; + + /* set ssk->sk_socket of accept()ed flows to mptcp socket. + * This is needed so NOSPACE flag can be set from tcp stack. + */ + __mptcp_flush_join_list(msk); + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + if (!ssk->sk_socket) + mptcp_sock_graft(ssk, newsock); + } + } + + if (inet_csk_listen_poll(ssock->sk)) + set_bit(MPTCP_DATA_READY, &msk->flags); + sock_put(ssock->sk); + return err; + +unlock_fail: + release_sock(sock->sk); + return -EINVAL; +} + +static __poll_t mptcp_check_readable(struct mptcp_sock *msk) +{ + return test_bit(MPTCP_DATA_READY, &msk->flags) ? EPOLLIN | EPOLLRDNORM : + 0; +} + +static __poll_t mptcp_poll(struct file *file, struct socket *sock, + struct poll_table_struct *wait) +{ + struct sock *sk = sock->sk; + struct mptcp_sock *msk; + __poll_t mask = 0; + int state; + + msk = mptcp_sk(sk); + sock_poll_wait(file, sock, wait); + + state = inet_sk_state_load(sk); + pr_debug("msk=%p state=%d flags=%lx", msk, state, msk->flags); + if (state == TCP_LISTEN) + return mptcp_check_readable(msk); + + if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) { + mask |= mptcp_check_readable(msk); + if (test_bit(MPTCP_SEND_SPACE, &msk->flags)) + mask |= EPOLLOUT | EPOLLWRNORM; + } + if (sk->sk_shutdown & RCV_SHUTDOWN) + mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP; + + return mask; +} + +static int mptcp_shutdown(struct socket *sock, int how) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct mptcp_subflow_context *subflow; + int ret = 0; + + pr_debug("sk=%p, how=%d", msk, how); + + lock_sock(sock->sk); + + how++; + if ((how & ~SHUTDOWN_MASK) || !how) { + ret = -EINVAL; + goto out_unlock; + } + + if (sock->state == SS_CONNECTING) { + if ((1 << sock->sk->sk_state) & + (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE)) + sock->state = SS_DISCONNECTING; + else + sock->state = SS_CONNECTED; + } + + /* If we've already sent a FIN, or it's a closed state, skip this. */ + if (__mptcp_check_fallback(msk)) { + if (how == SHUT_WR || how == SHUT_RDWR) + inet_sk_state_store(sock->sk, TCP_FIN_WAIT1); + + mptcp_for_each_subflow(msk, subflow) { + struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow); + + mptcp_subflow_shutdown(sock->sk, tcp_sk, how); + } + } else if ((how & SEND_SHUTDOWN) && + ((1 << sock->sk->sk_state) & + (TCPF_ESTABLISHED | TCPF_SYN_SENT | + TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) && + mptcp_close_state(sock->sk)) { + __mptcp_flush_join_list(msk); + + WRITE_ONCE(msk->write_seq, msk->write_seq + 1); + WRITE_ONCE(msk->snd_data_fin_enable, 1); + + mptcp_for_each_subflow(msk, subflow) { + struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow); + + mptcp_subflow_shutdown(sock->sk, tcp_sk, how); + } + } + + /* Wake up anyone sleeping in poll. */ + sock->sk->sk_state_change(sock->sk); + +out_unlock: + release_sock(sock->sk); + + return ret; +} + +static const struct proto_ops mptcp_stream_ops = { + .family = PF_INET, + .owner = THIS_MODULE, + .release = inet_release, + .bind = mptcp_bind, + .connect = mptcp_stream_connect, + .socketpair = sock_no_socketpair, + .accept = mptcp_stream_accept, + .getname = inet_getname, + .poll = mptcp_poll, + .ioctl = inet_ioctl, + .gettstamp = sock_gettstamp, + .listen = mptcp_listen, + .shutdown = mptcp_shutdown, + .setsockopt = sock_common_setsockopt, + .getsockopt = sock_common_getsockopt, + .sendmsg = inet_sendmsg, + .recvmsg = inet_recvmsg, + .mmap = sock_no_mmap, + .sendpage = inet_sendpage, +}; + +static struct inet_protosw mptcp_protosw = { + .type = SOCK_STREAM, + .protocol = IPPROTO_MPTCP, + .prot = &mptcp_prot, + .ops = &mptcp_stream_ops, + .flags = INET_PROTOSW_ICSK, +}; + +void __init mptcp_proto_init(void) +{ + mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo; + + if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL)) + panic("Failed to allocate MPTCP pcpu counter\n"); + + mptcp_subflow_init(); + mptcp_pm_init(); + mptcp_token_init(); + + if (proto_register(&mptcp_prot, 1) != 0) + panic("Failed to register MPTCP proto.\n"); + + inet_register_protosw(&mptcp_protosw); + + BUILD_BUG_ON(sizeof(struct mptcp_skb_cb) > sizeof_field(struct sk_buff, cb)); +} + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +static const struct proto_ops mptcp_v6_stream_ops = { + .family = PF_INET6, + .owner = THIS_MODULE, + .release = inet6_release, + .bind = mptcp_bind, + .connect = mptcp_stream_connect, + .socketpair = sock_no_socketpair, + .accept = mptcp_stream_accept, + .getname = inet6_getname, + .poll = mptcp_poll, + .ioctl = inet6_ioctl, + .gettstamp = sock_gettstamp, + .listen = mptcp_listen, + .shutdown = mptcp_shutdown, + .setsockopt = sock_common_setsockopt, + .getsockopt = sock_common_getsockopt, + .sendmsg = inet6_sendmsg, + .recvmsg = inet6_recvmsg, + .mmap = sock_no_mmap, + .sendpage = inet_sendpage, +#ifdef CONFIG_COMPAT + .compat_ioctl = inet6_compat_ioctl, +#endif +}; + +static struct proto mptcp_v6_prot; + +static struct inet_protosw mptcp_v6_protosw = { + .type = SOCK_STREAM, + .protocol = IPPROTO_MPTCP, + .prot = &mptcp_v6_prot, + .ops = &mptcp_v6_stream_ops, + .flags = INET_PROTOSW_ICSK, +}; + +int __init mptcp_proto_v6_init(void) +{ + int err; + + mptcp_v6_prot = mptcp_prot; + strcpy(mptcp_v6_prot.name, "MPTCPv6"); + mptcp_v6_prot.slab = NULL; + mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock); + + err = proto_register(&mptcp_v6_prot, 1); + if (err) + return err; + + err = inet6_register_protosw(&mptcp_v6_protosw); + if (err) + proto_unregister(&mptcp_v6_prot); + + return err; +} +#endif |