diff options
Diffstat (limited to 'net/mptcp/protocol.c')
| -rw-r--r-- | net/mptcp/protocol.c | 1286 |
1 files changed, 1286 insertions, 0 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c new file mode 100644 index 000000000000..3bccee455688 --- /dev/null +++ b/net/mptcp/protocol.c @@ -0,0 +1,1286 @@ +// 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> +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +#include <net/transp_v6.h> +#endif +#include <net/mptcp.h> +#include "protocol.h" + +#define MPTCP_SAME_STATE TCP_MAX_STATES + +static void __mptcp_close(struct sock *sk, long timeout); + +static const struct proto_ops *tcp_proto_ops(struct sock *sk) +{ +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + if (sk->sk_family == AF_INET6) + return &inet6_stream_ops; +#endif + return &inet_stream_ops; +} + +/* MP_CAPABLE handshake failed, convert msk to plain tcp, replacing + * socket->sk and stream ops and destroying msk + * return the msk socket, as we can't access msk anymore after this function + * completes + * Called with msk lock held, releases such lock before returning + */ +static struct socket *__mptcp_fallback_to_tcp(struct mptcp_sock *msk, + struct sock *ssk) +{ + struct mptcp_subflow_context *subflow; + struct socket *sock; + struct sock *sk; + + sk = (struct sock *)msk; + sock = sk->sk_socket; + subflow = mptcp_subflow_ctx(ssk); + + /* detach the msk socket */ + list_del_init(&subflow->node); + sock_orphan(sk); + sock->sk = NULL; + + /* socket is now TCP */ + lock_sock(ssk); + sock_graft(ssk, sock); + if (subflow->conn) { + /* We can't release the ULP data on a live socket, + * restore the tcp callback + */ + mptcp_subflow_tcp_fallback(ssk, subflow); + sock_put(subflow->conn); + subflow->conn = NULL; + } + release_sock(ssk); + sock->ops = tcp_proto_ops(ssk); + + /* destroy the left-over msk sock */ + __mptcp_close(sk, 0); + return sock; +} + +/* 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_needs_tcp_fallback(const struct mptcp_sock *msk) +{ + return msk->first && !sk_is_mptcp(msk->first); +} + +/* if the mp_capable handshake has failed, it fallbacks msk to plain TCP, + * releases the socket lock and returns a reference to the now TCP socket. + * Otherwise returns NULL + */ +static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk) +{ + sock_owned_by_me((const struct sock *)msk); + + if (likely(!__mptcp_needs_tcp_fallback(msk))) + return NULL; + + if (msk->subflow) { + /* the first subflow is an active connection, discart the + * paired socket + */ + msk->subflow->sk = NULL; + sock_release(msk->subflow); + msk->subflow = NULL; + } + + return __mptcp_fallback_to_tcp(msk, msk->first); +} + +static bool __mptcp_can_create_subflow(const struct mptcp_sock *msk) +{ + return !msk->first; +} + +static struct socket *__mptcp_socket_create(struct mptcp_sock *msk, int state) +{ + struct mptcp_subflow_context *subflow; + struct sock *sk = (struct sock *)msk; + struct socket *ssock; + int err; + + ssock = __mptcp_nmpc_socket(msk); + if (ssock) + goto set_state; + + if (!__mptcp_can_create_subflow(msk)) + return ERR_PTR(-EINVAL); + + err = mptcp_subflow_create_socket(sk, &ssock); + if (err) + return ERR_PTR(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; + +set_state: + if (state != MPTCP_SAME_STATE) + inet_sk_state_store(sk, state); + return ssock; +} + +static struct sock *mptcp_subflow_get(const struct mptcp_sock *msk) +{ + struct mptcp_subflow_context *subflow; + + sock_owned_by_me((const struct sock *)msk); + + mptcp_for_each_subflow(msk, subflow) { + return mptcp_subflow_tcp_sock(subflow); + } + + return NULL; +} + +static bool mptcp_ext_cache_refill(struct mptcp_sock *msk) +{ + if (!msk->cached_ext) + msk->cached_ext = __skb_ext_alloc(); + + 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 inline bool mptcp_skb_can_collapse_to(const struct mptcp_sock *msk, + 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 == msk->write_seq; +} + +static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, + struct msghdr *msg, long *timeo, int *pmss_now, + int *ps_goal) +{ + int mss_now, avail_size, size_goal, ret; + struct mptcp_sock *msk = mptcp_sk(sk); + struct mptcp_ext *mpext = NULL; + struct sk_buff *skb, *tail; + bool can_collapse = false; + struct page_frag *pfrag; + 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 + */ + pfrag = sk_page_frag(sk); + while (!sk_page_frag_refill(ssk, pfrag) || + !mptcp_ext_cache_refill(msk)) { + ret = sk_stream_wait_memory(ssk, timeo); + if (ret) + return ret; + if (unlikely(__mptcp_needs_tcp_fallback(msk))) + return 0; + } + + /* 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(msk, skb, mpext); + if (!can_collapse) + TCP_SKB_CB(skb)->eor = 1; + else + avail_size = size_goal - skb->len; + } + psize = min_t(size_t, pfrag->size - pfrag->offset, avail_size); + + /* Copy to page */ + pr_debug("left=%zu", msg_data_left(msg)); + psize = copy_page_from_iter(pfrag->page, pfrag->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; + + /* 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, pfrag->page, pfrag->offset, psize, + msg->msg_flags | MSG_SENDPAGE_NOTLAST); + if (ret <= 0) + return ret; + if (unlikely(ret < psize)) + iov_iter_revert(&msg->msg_iter, psize - ret); + + /* 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 = msk->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: + pfrag->offset += ret; + msk->write_seq += ret; + mptcp_subflow_ctx(ssk)->rel_write_seq += ret; + + return ret; +} + +static void ssk_check_wmem(struct mptcp_sock *msk, struct sock *ssk) +{ + struct socket *sock; + + if (likely(sk_stream_is_writeable(ssk))) + return; + + sock = READ_ONCE(ssk->sk_socket); + + if (sock) { + clear_bit(MPTCP_SEND_SPACE, &msk->flags); + smp_mb__after_atomic(); + /* set NOSPACE only after clearing SEND_SPACE flag */ + set_bit(SOCK_NOSPACE, &sock->flags); + } +} + +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 socket *ssock; + size_t copied = 0; + struct sock *ssk; + long timeo; + + if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL)) + return -EOPNOTSUPP; + + lock_sock(sk); + ssock = __mptcp_tcp_fallback(msk); + if (unlikely(ssock)) { +fallback: + pr_debug("fallback passthrough"); + ret = sock_sendmsg(ssock, msg); + return ret >= 0 ? ret + copied : (copied ? copied : ret); + } + + timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); + + ssk = mptcp_subflow_get(msk); + if (!ssk) { + release_sock(sk); + return -ENOTCONN; + } + + pr_debug("conn_list->subflow=%p", ssk); + + lock_sock(ssk); + while (msg_data_left(msg)) { + ret = mptcp_sendmsg_frag(sk, ssk, msg, &timeo, &mss_now, + &size_goal); + if (ret < 0) + break; + if (ret == 0 && unlikely(__mptcp_needs_tcp_fallback(msk))) { + release_sock(ssk); + ssock = __mptcp_tcp_fallback(msk); + goto fallback; + } + + copied += ret; + } + + if (copied) { + ret = copied; + tcp_push(ssk, msg->msg_flags, mss_now, tcp_sk(ssk)->nonagle, + size_goal); + } + + ssk_check_wmem(msk, ssk); + release_sock(ssk); + release_sock(sk); + return ret; +} + +int mptcp_read_actor(read_descriptor_t *desc, struct sk_buff *skb, + unsigned int offset, size_t len) +{ + struct mptcp_read_arg *arg = desc->arg.data; + size_t copy_len; + + copy_len = min(desc->count, len); + + if (likely(arg->msg)) { + int err; + + err = skb_copy_datagram_msg(skb, offset, arg->msg, copy_len); + if (err) { + pr_debug("error path"); + desc->error = err; + return err; + } + } else { + pr_debug("Flushing skb payload"); + } + + desc->count -= copy_len; + + pr_debug("consumed %zu bytes, %zu left", copy_len, desc->count); + return copy_len; +} + +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(struct sock *sk, struct msghdr *msg, size_t len, + int nonblock, int flags, int *addr_len) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + struct mptcp_subflow_context *subflow; + bool more_data_avail = false; + struct mptcp_read_arg arg; + read_descriptor_t desc; + bool wait_data = false; + struct socket *ssock; + struct tcp_sock *tp; + bool done = false; + struct sock *ssk; + int copied = 0; + int target; + long timeo; + + if (msg->msg_flags & ~(MSG_WAITALL | MSG_DONTWAIT)) + return -EOPNOTSUPP; + + lock_sock(sk); + ssock = __mptcp_tcp_fallback(msk); + if (unlikely(ssock)) { +fallback: + pr_debug("fallback-read subflow=%p", + mptcp_subflow_ctx(ssock->sk)); + copied = sock_recvmsg(ssock, msg, flags); + return copied; + } + + arg.msg = msg; + desc.arg.data = &arg; + desc.error = 0; + + timeo = sock_rcvtimeo(sk, nonblock); + + len = min_t(size_t, len, INT_MAX); + target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); + + while (!done) { + u32 map_remaining; + int bytes_read; + + ssk = mptcp_subflow_recv_lookup(msk); + pr_debug("msk=%p ssk=%p", msk, ssk); + if (!ssk) + goto wait_for_data; + + subflow = mptcp_subflow_ctx(ssk); + tp = tcp_sk(ssk); + + lock_sock(ssk); + do { + /* try to read as much data as available */ + map_remaining = subflow->map_data_len - + mptcp_subflow_get_map_offset(subflow); + desc.count = min_t(size_t, len - copied, map_remaining); + pr_debug("reading %zu bytes, copied %d", desc.count, + copied); + bytes_read = tcp_read_sock(ssk, &desc, + mptcp_read_actor); + if (bytes_read < 0) { + if (!copied) + copied = bytes_read; + done = true; + goto next; + } + + pr_debug("msk ack_seq=%llx -> %llx", msk->ack_seq, + msk->ack_seq + bytes_read); + msk->ack_seq += bytes_read; + copied += bytes_read; + if (copied >= len) { + done = true; + goto next; + } + if (tp->urg_data && tp->urg_seq == tp->copied_seq) { + pr_err("Urgent data present, cannot proceed"); + done = true; + goto next; + } +next: + more_data_avail = mptcp_subflow_data_available(ssk); + } while (more_data_avail && !done); + release_sock(ssk); + continue; + +wait_for_data: + more_data_avail = false; + + /* 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 (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); + wait_data = true; + mptcp_wait_data(sk, &timeo); + if (unlikely(__mptcp_tcp_fallback(msk))) + goto fallback; + } + + if (more_data_avail) { + if (!test_bit(MPTCP_DATA_READY, &msk->flags)) + set_bit(MPTCP_DATA_READY, &msk->flags); + } else if (!wait_data) { + clear_bit(MPTCP_DATA_READY, &msk->flags); + + /* .. race-breaker: ssk might get new data after last + * data_available() returns false. + */ + ssk = mptcp_subflow_recv_lookup(msk); + if (unlikely(ssk)) + set_bit(MPTCP_DATA_READY, &msk->flags); + } + + release_sock(sk); + return copied; +} + +/* 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. + */ +static 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 int __mptcp_init_sock(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + INIT_LIST_HEAD(&msk->conn_list); + __set_bit(MPTCP_SEND_SPACE, &msk->flags); + + msk->first = NULL; + + return 0; +} + +static int mptcp_init_sock(struct sock *sk) +{ + if (!mptcp_is_enabled(sock_net(sk))) + return -ENOPROTOOPT; + + return __mptcp_init_sock(sk); +} + +static void mptcp_subflow_shutdown(struct sock *ssk, int how) +{ + lock_sock(ssk); + + switch (ssk->sk_state) { + case TCP_LISTEN: + if (!(how & RCV_SHUTDOWN)) + break; + /* fall through */ + case TCP_SYN_SENT: + tcp_disconnect(ssk, O_NONBLOCK); + break; + default: + ssk->sk_shutdown |= how; + tcp_shutdown(ssk, how); + break; + } + + /* Wake up anyone sleeping in poll. */ + ssk->sk_state_change(ssk); + release_sock(ssk); +} + +/* Called with msk lock held, releases such lock before returning */ +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); + + mptcp_token_destroy(msk->token); + inet_sk_state_store(sk, TCP_CLOSE); + + list_splice_init(&msk->conn_list, &conn_list); + + 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); + } + + sk_common_release(sk); +} + +static void mptcp_close(struct sock *sk, long timeout) +{ + lock_sock(sk); + __mptcp_close(sk, timeout); +} + +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 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; + u64 ack_seq; + + subflow = mptcp_subflow_ctx(newsk); + lock_sock(sk); + + local_bh_disable(); + new_mptcp_sock = sk_clone_lock(sk, GFP_ATOMIC); + if (!new_mptcp_sock) { + *err = -ENOBUFS; + local_bh_enable(); + release_sock(sk); + mptcp_subflow_shutdown(newsk, SHUT_RDWR + 1); + tcp_close(newsk, 0); + return NULL; + } + + __mptcp_init_sock(new_mptcp_sock); + + msk = mptcp_sk(new_mptcp_sock); + msk->local_key = subflow->local_key; + msk->token = subflow->token; + msk->subflow = NULL; + msk->first = newsk; + + mptcp_token_update_accept(newsk, new_mptcp_sock); + + msk->write_seq = subflow->idsn + 1; + if (subflow->can_ack) { + msk->can_ack = true; + msk->remote_key = subflow->remote_key; + mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq); + ack_seq++; + msk->ack_seq = ack_seq; + } + newsk = new_mptcp_sock; + mptcp_copy_inaddrs(newsk, ssk); + list_add(&subflow->node, &msk->conn_list); + + /* will be fully established at mptcp_stream_accept() + * completion. + */ + inet_sk_state_store(new_mptcp_sock, TCP_SYN_RECV); + bh_unlock_sock(new_mptcp_sock); + local_bh_enable(); + release_sock(sk); + + /* the subflow can already receive packet, avoid racing with + * the receive path and process the pending ones + */ + lock_sock(ssk); + subflow->rel_write_seq = 1; + subflow->tcp_sock = ssk; + subflow->conn = new_mptcp_sock; + if (unlikely(!skb_queue_empty(&ssk->sk_receive_queue))) + mptcp_subflow_data_available(ssk); + release_sock(ssk); + } + + return newsk; +} + +static void mptcp_destroy(struct sock *sk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + if (msk->cached_ext) + __skb_ext_put(msk->cached_ext); +} + +static int mptcp_setsockopt(struct sock *sk, int level, int optname, + char __user *optval, unsigned int optlen) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + int ret = -EOPNOTSUPP; + struct socket *ssock; + struct sock *ssk; + + pr_debug("msk=%p", msk); + + /* @@ the meaning of setsockopt() when the socket is connected and + * there are multiple subflows is not defined. + */ + lock_sock(sk); + ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE); + if (IS_ERR(ssock)) { + release_sock(sk); + return ret; + } + + ssk = ssock->sk; + sock_hold(ssk); + release_sock(sk); + + ret = tcp_setsockopt(ssk, level, optname, optval, optlen); + sock_put(ssk); + + return ret; +} + +static int mptcp_getsockopt(struct sock *sk, int level, int optname, + char __user *optval, int __user *option) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + int ret = -EOPNOTSUPP; + struct socket *ssock; + struct sock *ssk; + + pr_debug("msk=%p", msk); + + /* @@ the meaning of getsockopt() when the socket is connected and + * there are multiple subflows is not defined. + */ + lock_sock(sk); + ssock = __mptcp_socket_create(msk, MPTCP_SAME_STATE); + if (IS_ERR(ssock)) { + release_sock(sk); + return ret; + } + + ssk = ssock->sk; + sock_hold(ssk); + release_sock(sk); + + ret = tcp_getsockopt(ssk, level, optname, optval, option); + sock_put(ssk); + + return ret; +} + +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); + + if (!subflow->mp_capable) + return; + + 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; + subflow->rel_write_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->token, subflow->token); + WRITE_ONCE(msk->write_seq, subflow->idsn + 1); + WRITE_ONCE(msk->ack_seq, ack_seq); + WRITE_ONCE(msk->can_ack, 1); +} + +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); +} + +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, + .close = mptcp_close, + .accept = mptcp_accept, + .setsockopt = mptcp_setsockopt, + .getsockopt = mptcp_getsockopt, + .shutdown = tcp_shutdown, + .destroy = mptcp_destroy, + .sendmsg = mptcp_sendmsg, + .recvmsg = mptcp_recvmsg, + .hash = inet_hash, + .unhash = inet_unhash, + .get_port = mptcp_get_port, + .stream_memory_free = mptcp_memory_free, + .obj_size = sizeof(struct mptcp_sock), + .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_socket_create(msk, MPTCP_SAME_STATE); + if (IS_ERR(ssock)) { + err = PTR_ERR(ssock); + 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 int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, + int addr_len, int flags) +{ + struct mptcp_sock *msk = mptcp_sk(sock->sk); + struct socket *ssock; + int err; + + lock_sock(sock->sk); + ssock = __mptcp_socket_create(msk, TCP_SYN_SENT); + if (IS_ERR(ssock)) { + err = PTR_ERR(ssock); + goto unlock; + } + +#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_ctx(ssock->sk)->request_mptcp = 0; +#endif + + err = ssock->ops->connect(ssock, uaddr, addr_len, flags); + inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk)); + mptcp_copy_inaddrs(sock->sk, ssock->sk); + +unlock: + release_sock(sock->sk); + return err; +} + +static int mptcp_v4_getname(struct socket *sock, struct sockaddr *uaddr, + int peer) +{ + if (sock->sk->sk_prot == &tcp_prot) { + /* we are being invoked from __sys_accept4, after + * mptcp_accept() has just 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 inet_getname(sock, uaddr, peer); +} + +#if IS_ENABLED(CONFIG_MPTCP_IPV6) +static int mptcp_v6_getname(struct socket *sock, struct sockaddr *uaddr, + int peer) +{ + if (sock->sk->sk_prot == &tcpv6_prot) { + /* we are being invoked from __sys_accept4 after + * mptcp_accept() has accepted a non-mp-capable + * subflow: sk is a tcp_sk, not mptcp. + * + * Hand the socket over to tcp so all further + * socket ops bypass mptcp. + */ + sock->ops = &inet6_stream_ops; + } + + return inet6_getname(sock, uaddr, peer); +} +#endif + +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_socket_create(msk, TCP_LISTEN); + if (IS_ERR(ssock)) { + err = PTR_ERR(ssock); + goto unlock; + } + + 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 bool is_tcp_proto(const struct proto *p) +{ +#if IS_ENABLED(CONFIG_MPTCP_IPV6) + return p == &tcp_prot || p == &tcpv6_prot; +#else + return p == &tcp_prot; +#endif +} + +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; + + sock_hold(ssock->sk); + release_sock(sock->sk); + + err = ssock->ops->accept(sock, newsock, flags, kern); + if (err == 0 && !is_tcp_proto(newsock->sk->sk_prot)) { + 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. + */ + list_for_each_entry(subflow, &msk->conn_list, node) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + if (!ssk->sk_socket) + mptcp_sock_graft(ssk, newsock); + } + + inet_sk_state_store(newsock->sk, TCP_ESTABLISHED); + } + + sock_put(ssock->sk); + return err; + +unlock_fail: + release_sock(sock->sk); + return -EINVAL; +} + +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; + struct socket *ssock; + __poll_t mask = 0; + + msk = mptcp_sk(sk); + lock_sock(sk); + ssock = __mptcp_nmpc_socket(msk); + if (ssock) { + mask = ssock->ops->poll(file, ssock, wait); + release_sock(sk); + return mask; + } + + release_sock(sk); + sock_poll_wait(file, sock, wait); + lock_sock(sk); + ssock = __mptcp_tcp_fallback(msk); + if (unlikely(ssock)) + return ssock->ops->poll(file, ssock, NULL); + + if (test_bit(MPTCP_DATA_READY, &msk->flags)) + mask = EPOLLIN | EPOLLRDNORM; + if (sk_stream_is_writeable(sk) && + test_bit(MPTCP_SEND_SPACE, &msk->flags)) + mask |= EPOLLOUT | EPOLLWRNORM; + if (sk->sk_shutdown & RCV_SHUTDOWN) + mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP; + + release_sock(sk); + + 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); + + if (how == SHUT_WR || how == SHUT_RDWR) + inet_sk_state_store(sock->sk, TCP_FIN_WAIT1); + + 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; + } + + mptcp_for_each_subflow(msk, subflow) { + struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow); + + mptcp_subflow_shutdown(tcp_sk, how); + } + +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 = mptcp_v4_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, +#ifdef CONFIG_COMPAT + .compat_setsockopt = compat_sock_common_setsockopt, + .compat_getsockopt = compat_sock_common_getsockopt, +#endif +}; + +static struct inet_protosw mptcp_protosw = { + .type = SOCK_STREAM, + .protocol = IPPROTO_MPTCP, + .prot = &mptcp_prot, + .ops = &mptcp_stream_ops, + .flags = INET_PROTOSW_ICSK, +}; + +void mptcp_proto_init(void) +{ + mptcp_prot.h.hashinfo = tcp_prot.h.hashinfo; + + mptcp_subflow_init(); + + if (proto_register(&mptcp_prot, 1) != 0) + panic("Failed to register MPTCP proto.\n"); + + inet_register_protosw(&mptcp_protosw); +} + +#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 = mptcp_v6_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_setsockopt = compat_sock_common_setsockopt, + .compat_getsockopt = compat_sock_common_getsockopt, +#endif +}; + +static struct proto mptcp_v6_prot; + +static void mptcp_v6_destroy(struct sock *sk) +{ + mptcp_destroy(sk); + inet6_destroy_sock(sk); +} + +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 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.destroy = mptcp_v6_destroy; + mptcp_v6_prot.obj_size = sizeof(struct mptcp_sock) + + sizeof(struct ipv6_pinfo); + + 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 |