| Message ID | 20200605092227.2420308-1-dcaratti@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | Matthieu Baerts |
| Headers | show |
| Series | [mptcp-next,v2] net: mptcp: improve fallback to TCP | expand |
On Fri, 2020-06-05 at 11:22 +0200, Davide Caratti wrote: > keep using MPTCP sockets and a "dummy mapping" in case of fallback to > regular TCP. Skip adding DSS option on send, if TCP fallback has been > done earlier. > > Notes: I'm unsure on what to do in mptcp_clean_una() to do a one-time > flush of the retransmit queue, as per Mat's suggestion. Any advice? > > Changes since v1 > - rebase on top of Paolo's fix for NULL dereference in mptcp_recvmsg() > > Changes since RFC v2: > - use a bit in msk->flags, rather than a dedicated boolean in struct > msk. This bit is going to be used in combination with another one, > TCP_FALLBACK_ALLOWED, that is 1 at the first subflow creation > and gets cleared once TCP fallback is no more allowed. > - separate code that adds support for "infinite mapping", and use > the term "dummy" instead of "infinite". Suggested by Mat > - remove inappropriate call to __mptcp_do_fallback() in > mptcp_accept() (Paolo) > > Changes since RFC v1: > - use a dedicated member of struct msk to indicate that a fallback > ha happened, use it in case of infinite mapping > - don't delete skb_ext in case of infinite mapping (Mat) > - test the value of pm.subflows on reception of an infinite map to > ensure that no other subflow is currently opened (Mat) > - in mptcp_established_options(), avoid adding TCP options in case > of fallback indication; simplify sendmsg()/recvmsg()/poll() to > keep using the MPTCP socket in case of TCP fallback. Set the > fallback indication in case subflow is not mp_capable after > successful 3-way handshake, instead of flipping 'is_mptcp' > (Paolo/Mat) > - remove deadcode in mptcp_finish_connect, and increment > MPTCP_MIB_MPCAPABLEACTIVEFALLBACK in subflow_finish_connect > (Paolo) > > BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/11 > BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/22 > Signed-off-by: Davide Caratti <dcaratti@redhat.com> > --- > net/mptcp/options.c | 9 ++++- > net/mptcp/protocol.c | 78 ++++++++++---------------------------------- > net/mptcp/protocol.h | 34 +++++++++++++++++++ > net/mptcp/subflow.c | 46 +++++++++++++++++--------- > 4 files changed, 90 insertions(+), 77 deletions(-) > > diff --git a/net/mptcp/options.c b/net/mptcp/options.c > index 01f1f4cf4902..cf0b59ead1e4 100644 > --- a/net/mptcp/options.c > +++ b/net/mptcp/options.c > @@ -624,6 +624,9 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, > > opts->suboptions = 0; > > + if (unlikely(mptcp_check_fallback(sk))) > + return false; > + > if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts)) > ret = true; > else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining, > @@ -714,7 +717,8 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, > */ > if (!mp_opt->mp_capable) { > subflow->mp_capable = 0; > - tcp_sk(sk)->is_mptcp = 0; > + pr_fallback(msk); > + __mptcp_do_fallback(msk); > return false; > } > > @@ -814,6 +818,9 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb, > struct mptcp_options_received mp_opt; > struct mptcp_ext *mpext; > > + if (__mptcp_check_fallback(msk)) > + return; > + > mptcp_get_options(skb, &mp_opt); > if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) > return; > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 5d7f4cd2c8e6..1d907519c223 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -52,11 +52,6 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk) > return msk->subflow; > } > > -static bool __mptcp_needs_tcp_fallback(const struct mptcp_sock *msk) > -{ > - return msk->first && !sk_is_mptcp(msk->first); > -} > - > static struct socket *mptcp_is_tcpsk(struct sock *sk) > { > struct socket *sock = sk->sk_socket; > @@ -94,7 +89,7 @@ static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk) > if (unlikely(sock)) > return sock; > > - if (likely(!__mptcp_needs_tcp_fallback(msk))) > + if (likely(!__mptcp_check_fallback(msk))) > return NULL; > > return msk->subflow; > @@ -229,6 +224,15 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, > if (!skb) > 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) { > @@ -445,8 +449,15 @@ static void mptcp_clean_una(struct sock *sk) > { > struct mptcp_sock *msk = mptcp_sk(sk); > struct mptcp_data_frag *dtmp, *dfrag; > - u64 snd_una = atomic64_read(&msk->snd_una); > 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)) > @@ -719,7 +730,6 @@ 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; > - struct socket *ssock; > size_t copied = 0; > struct sock *ssk; > bool tx_ok; > @@ -738,15 +748,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) > goto out; > } > > -fallback: > - ssock = __mptcp_tcp_fallback(msk); > - if (unlikely(ssock)) { > - release_sock(sk); > - pr_debug("fallback passthrough"); > - ret = sock_sendmsg(ssock, msg); > - return ret >= 0 ? ret + copied : (copied ? copied : ret); > - } > - > pfrag = sk_page_frag(sk); > restart: > mptcp_clean_una(sk); > @@ -798,17 +799,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) > } > break; > } > - if (ret == 0 && unlikely(__mptcp_needs_tcp_fallback(msk))) { > - /* Can happen for passive sockets: > - * 3WHS negotiated MPTCP, but first packet after is > - * plain TCP (e.g. due to middlebox filtering unknown > - * options). > - * > - * Fall back to TCP. > - */ > - release_sock(ssk); > - goto fallback; > - } > > copied += ret; > > @@ -951,7 +941,6 @@ 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 socket *ssock; > int copied = 0; > int target; > long timeo; > @@ -960,16 +949,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, > return -EOPNOTSUPP; > > lock_sock(sk); > - ssock = __mptcp_tcp_fallback(msk); > - if (unlikely(ssock)) { > -fallback: > - release_sock(sk); > - pr_debug("fallback-read subflow=%p", > - mptcp_subflow_ctx(ssock->sk)); > - copied = sock_recvmsg(ssock, msg, flags); > - return copied; > - } > - > timeo = sock_rcvtimeo(sk, nonblock); > > len = min_t(size_t, len, INT_MAX); > @@ -1032,9 +1011,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, > > pr_debug("block timeout %ld", timeo); > mptcp_wait_data(sk, &timeo); > - ssock = __mptcp_tcp_fallback(msk); > - if (unlikely(ssock)) > - goto fallback; > } > > if (skb_queue_empty(&sk->sk_receive_queue)) { > @@ -1659,12 +1635,6 @@ void mptcp_finish_connect(struct sock *ssk) > sk = subflow->conn; > msk = mptcp_sk(sk); > > - if (!subflow->mp_capable) { > - MPTCP_INC_STATS(sock_net(sk), > - MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); > - return; > - } > - > pr_debug("msk=%p, token=%u", sk, subflow->token); > > mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq); > @@ -1964,21 +1934,9 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock, > { > 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_tcp_fallback(msk); > - if (!ssock) > - 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); > > diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h > index 0592fec3418b..2b39d5344d95 100644 > --- a/net/mptcp/protocol.h > +++ b/net/mptcp/protocol.h > @@ -89,6 +89,7 @@ > #define MPTCP_SEND_SPACE 1 > #define MPTCP_WORK_RTX 2 > #define MPTCP_WORK_EOF 3 > +#define MPTCP_FALLBACK_DONE 4 > > struct mptcp_options_received { > u64 sndr_key; > @@ -461,4 +462,37 @@ static inline bool before64(__u64 seq1, __u64 seq2) > > void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops); > > +static inline bool __mptcp_check_fallback(struct mptcp_sock *msk) > +{ > + return test_bit(MPTCP_FALLBACK_DONE, &msk->flags); > +} > + > +static inline bool mptcp_check_fallback(struct sock *sk) > +{ > + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); > + struct mptcp_sock *msk = mptcp_sk(subflow->conn); > + > + return __mptcp_check_fallback(msk); > +} > + > +static inline void __mptcp_do_fallback(struct mptcp_sock *msk) > +{ > + if (test_bit(MPTCP_FALLBACK_DONE, &msk->flags)) { > + pr_debug("TCP fallback already done (msk=%p)", msk); > + return; > + } > + set_bit(MPTCP_FALLBACK_DONE, &msk->flags); > +} > + > +static inline void mptcp_do_fallback(struct sock *sk) > +{ > + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); > + struct mptcp_sock *msk = mptcp_sk(subflow->conn); > + > + __mptcp_do_fallback(msk); > +} > + > +#define pr_fallback(a) do { pr_debug("%s:fallback to TCP (msk=%p)",\ > + __FUNCTION__, a); } while (0) > + > #endif /* __MPTCP_PROTOCOL_H */ > diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c > index 10b4770a1419..8245395f8354 100644 > --- a/net/mptcp/subflow.c > +++ b/net/mptcp/subflow.c > @@ -223,7 +223,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) > struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); > struct mptcp_options_received mp_opt; > struct sock *parent = subflow->conn; > - struct tcp_sock *tp = tcp_sk(sk); > > subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); > > @@ -237,6 +236,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) > return; > > subflow->conn_finished = 1; > + subflow->ssn_offset = TCP_SKB_CB(skb)->seq; > + pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset); > > mptcp_get_options(skb, &mp_opt); > if (subflow->request_mptcp && mp_opt.mp_capable) { > @@ -252,21 +253,19 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) > pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow, > subflow->thmac, subflow->remote_nonce); > } else if (subflow->request_mptcp) { > - tp->is_mptcp = 0; > + mptcp_do_fallback(sk); > + pr_fallback(mptcp_sk(subflow->conn)); > + MPTCP_INC_STATS(sock_net(sk), > + MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); > } > > - if (!tp->is_mptcp) > + if (mptcp_check_fallback(sk)) > return; > > if (subflow->mp_capable) { > pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk), > subflow->remote_key); > mptcp_finish_connect(sk); > - > - if (skb) { > - pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq); > - subflow->ssn_offset = TCP_SKB_CB(skb)->seq; > - } > } else if (subflow->mp_join) { > u8 hmac[SHA256_DIGEST_SIZE]; > > @@ -286,9 +285,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) > > memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); > > - if (skb) > - subflow->ssn_offset = TCP_SKB_CB(skb)->seq; > - > if (!mptcp_finish_join(sk)) > goto do_reset; > > @@ -564,7 +560,8 @@ enum mapping_status { > MAPPING_OK, > MAPPING_INVALID, > MAPPING_EMPTY, > - MAPPING_DATA_FIN > + MAPPING_DATA_FIN, > + MAPPING_DUMMY > }; > > static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq) > @@ -628,6 +625,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk) > if (!skb) > return MAPPING_EMPTY; > > + if (mptcp_check_fallback(ssk)) > + return MAPPING_DUMMY; > + > mpext = mptcp_get_ext(skb); > if (!mpext || !mpext->use_map) { > if (!subflow->map_valid && !skb->len) { > @@ -769,6 +769,16 @@ static bool subflow_check_data_avail(struct sock *ssk) > ssk->sk_err = EBADMSG; > goto fatal; > } > + if (status == MAPPING_DUMMY) { > + __mptcp_do_fallback(msk); > + skb = skb_peek(&ssk->sk_receive_queue); > + subflow->map_valid = 1; > + subflow->map_seq = READ_ONCE(msk->ack_seq); > + subflow->map_data_len = skb->len; > + subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - > + subflow->ssn_offset; > + return true; > + } > > if (status != MAPPING_OK) > return false; > @@ -892,14 +902,18 @@ static void subflow_data_ready(struct sock *sk) > { > struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); > struct sock *parent = subflow->conn; > + struct mptcp_sock *msk; > > - if (!subflow->mp_capable && !subflow->mp_join) { > - subflow->tcp_data_ready(sk); > - > + msk = mptcp_sk(parent); > + if (inet_sk_state_load(sk) == TCP_LISTEN) { > + set_bit(MPTCP_DATA_READY, &msk->flags); > parent->sk_data_ready(parent); > return; > } > > + WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && > + !subflow->mp_join); > + > if (mptcp_subflow_data_available(sk)) > mptcp_data_ready(parent, sk); > } > @@ -1122,7 +1136,7 @@ static void subflow_state_change(struct sock *sk) > * a fin packet carrying a DSS can be unnoticed if we don't trigger > * the data available machinery here. > */ > - if (subflow->mp_capable && mptcp_subflow_data_available(sk)) > + if (mptcp_subflow_data_available(sk)) > mptcp_data_ready(parent, sk); > > if (!(parent->sk_shutdown & RCV_SHUTDOWN) && The patch LGTM, modolo the follow-up to cope with issues/35 I propose to merge this as is, and handle fixes (and commit message rewrite) with squash-to patches. WDYT? Thanks! Paolo
Hi Paolo, Davide, On 08/06/2020 12:16, Paolo Abeni wrote: > On Fri, 2020-06-05 at 11:22 +0200, Davide Caratti wrote: (...) > The patch LGTM, modolo the follow-up to cope with issues/35 > > I propose to merge this as is, and handle fixes (and commit message > rewrite) with squash-to patches. > > WDYT? Sounds good to me! This will unblock Florian as well. Cheers, Matt
Hi Davide, Paolo, Mat, On 08/06/2020 12:16, Paolo Abeni wrote: > On Fri, 2020-06-05 at 11:22 +0200, Davide Caratti wrote: >> keep using MPTCP sockets and a "dummy mapping" in case of fallback to >> regular TCP. Skip adding DSS option on send, if TCP fallback has been >> done earlier. >> >> Notes: I'm unsure on what to do in mptcp_clean_una() to do a one-time >> flush of the retransmit queue, as per Mat's suggestion. Any advice? >> >> Changes since v1 >> - rebase on top of Paolo's fix for NULL dereference in mptcp_recvmsg() >> >> Changes since RFC v2: >> - use a bit in msk->flags, rather than a dedicated boolean in struct >> msk. This bit is going to be used in combination with another one, >> TCP_FALLBACK_ALLOWED, that is 1 at the first subflow creation >> and gets cleared once TCP fallback is no more allowed. >> - separate code that adds support for "infinite mapping", and use >> the term "dummy" instead of "infinite". Suggested by Mat >> - remove inappropriate call to __mptcp_do_fallback() in >> mptcp_accept() (Paolo) >> >> Changes since RFC v1: >> - use a dedicated member of struct msk to indicate that a fallback >> ha happened, use it in case of infinite mapping >> - don't delete skb_ext in case of infinite mapping (Mat) >> - test the value of pm.subflows on reception of an infinite map to >> ensure that no other subflow is currently opened (Mat) >> - in mptcp_established_options(), avoid adding TCP options in case >> of fallback indication; simplify sendmsg()/recvmsg()/poll() to >> keep using the MPTCP socket in case of TCP fallback. Set the >> fallback indication in case subflow is not mp_capable after >> successful 3-way handshake, instead of flipping 'is_mptcp' >> (Paolo/Mat) >> - remove deadcode in mptcp_finish_connect, and increment >> MPTCP_MIB_MPCAPABLEACTIVEFALLBACK in subflow_finish_connect >> (Paolo) >> >> BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/11 >> BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/22 >> Signed-off-by: Davide Caratti <dcaratti@redhat.com> Thank you for the patch and the reviews! This commit is now at the end of the export branch (before the two DO-NOT-MERGE ones), tests are all passing! @Davide: do not hesitate to create a new PR for Packetdrill ;-) Cheers, Matt
diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 01f1f4cf4902..cf0b59ead1e4 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -624,6 +624,9 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb, opts->suboptions = 0; + if (unlikely(mptcp_check_fallback(sk))) + return false; + if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts)) ret = true; else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining, @@ -714,7 +717,8 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *sk, */ if (!mp_opt->mp_capable) { subflow->mp_capable = 0; - tcp_sk(sk)->is_mptcp = 0; + pr_fallback(msk); + __mptcp_do_fallback(msk); return false; } @@ -814,6 +818,9 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb, struct mptcp_options_received mp_opt; struct mptcp_ext *mpext; + if (__mptcp_check_fallback(msk)) + return; + mptcp_get_options(skb, &mp_opt); if (!check_fully_established(msk, sk, subflow, skb, &mp_opt)) return; diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 5d7f4cd2c8e6..1d907519c223 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -52,11 +52,6 @@ static struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk) return msk->subflow; } -static bool __mptcp_needs_tcp_fallback(const struct mptcp_sock *msk) -{ - return msk->first && !sk_is_mptcp(msk->first); -} - static struct socket *mptcp_is_tcpsk(struct sock *sk) { struct socket *sock = sk->sk_socket; @@ -94,7 +89,7 @@ static struct socket *__mptcp_tcp_fallback(struct mptcp_sock *msk) if (unlikely(sock)) return sock; - if (likely(!__mptcp_needs_tcp_fallback(msk))) + if (likely(!__mptcp_check_fallback(msk))) return NULL; return msk->subflow; @@ -229,6 +224,15 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, if (!skb) 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) { @@ -445,8 +449,15 @@ static void mptcp_clean_una(struct sock *sk) { struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_data_frag *dtmp, *dfrag; - u64 snd_una = atomic64_read(&msk->snd_una); 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)) @@ -719,7 +730,6 @@ 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; - struct socket *ssock; size_t copied = 0; struct sock *ssk; bool tx_ok; @@ -738,15 +748,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) goto out; } -fallback: - ssock = __mptcp_tcp_fallback(msk); - if (unlikely(ssock)) { - release_sock(sk); - pr_debug("fallback passthrough"); - ret = sock_sendmsg(ssock, msg); - return ret >= 0 ? ret + copied : (copied ? copied : ret); - } - pfrag = sk_page_frag(sk); restart: mptcp_clean_una(sk); @@ -798,17 +799,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) } break; } - if (ret == 0 && unlikely(__mptcp_needs_tcp_fallback(msk))) { - /* Can happen for passive sockets: - * 3WHS negotiated MPTCP, but first packet after is - * plain TCP (e.g. due to middlebox filtering unknown - * options). - * - * Fall back to TCP. - */ - release_sock(ssk); - goto fallback; - } copied += ret; @@ -951,7 +941,6 @@ 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 socket *ssock; int copied = 0; int target; long timeo; @@ -960,16 +949,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, return -EOPNOTSUPP; lock_sock(sk); - ssock = __mptcp_tcp_fallback(msk); - if (unlikely(ssock)) { -fallback: - release_sock(sk); - pr_debug("fallback-read subflow=%p", - mptcp_subflow_ctx(ssock->sk)); - copied = sock_recvmsg(ssock, msg, flags); - return copied; - } - timeo = sock_rcvtimeo(sk, nonblock); len = min_t(size_t, len, INT_MAX); @@ -1032,9 +1011,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, pr_debug("block timeout %ld", timeo); mptcp_wait_data(sk, &timeo); - ssock = __mptcp_tcp_fallback(msk); - if (unlikely(ssock)) - goto fallback; } if (skb_queue_empty(&sk->sk_receive_queue)) { @@ -1659,12 +1635,6 @@ void mptcp_finish_connect(struct sock *ssk) sk = subflow->conn; msk = mptcp_sk(sk); - if (!subflow->mp_capable) { - MPTCP_INC_STATS(sock_net(sk), - MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); - return; - } - pr_debug("msk=%p, token=%u", sk, subflow->token); mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq); @@ -1964,21 +1934,9 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock, { 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_tcp_fallback(msk); - if (!ssock) - 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); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 0592fec3418b..2b39d5344d95 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -89,6 +89,7 @@ #define MPTCP_SEND_SPACE 1 #define MPTCP_WORK_RTX 2 #define MPTCP_WORK_EOF 3 +#define MPTCP_FALLBACK_DONE 4 struct mptcp_options_received { u64 sndr_key; @@ -461,4 +462,37 @@ static inline bool before64(__u64 seq1, __u64 seq2) void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops); +static inline bool __mptcp_check_fallback(struct mptcp_sock *msk) +{ + return test_bit(MPTCP_FALLBACK_DONE, &msk->flags); +} + +static inline bool mptcp_check_fallback(struct sock *sk) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + + return __mptcp_check_fallback(msk); +} + +static inline void __mptcp_do_fallback(struct mptcp_sock *msk) +{ + if (test_bit(MPTCP_FALLBACK_DONE, &msk->flags)) { + pr_debug("TCP fallback already done (msk=%p)", msk); + return; + } + set_bit(MPTCP_FALLBACK_DONE, &msk->flags); +} + +static inline void mptcp_do_fallback(struct sock *sk) +{ + struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct mptcp_sock *msk = mptcp_sk(subflow->conn); + + __mptcp_do_fallback(msk); +} + +#define pr_fallback(a) do { pr_debug("%s:fallback to TCP (msk=%p)",\ + __FUNCTION__, a); } while (0) + #endif /* __MPTCP_PROTOCOL_H */ diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 10b4770a1419..8245395f8354 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -223,7 +223,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); struct mptcp_options_received mp_opt; struct sock *parent = subflow->conn; - struct tcp_sock *tp = tcp_sk(sk); subflow->icsk_af_ops->sk_rx_dst_set(sk, skb); @@ -237,6 +236,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) return; subflow->conn_finished = 1; + subflow->ssn_offset = TCP_SKB_CB(skb)->seq; + pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset); mptcp_get_options(skb, &mp_opt); if (subflow->request_mptcp && mp_opt.mp_capable) { @@ -252,21 +253,19 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow, subflow->thmac, subflow->remote_nonce); } else if (subflow->request_mptcp) { - tp->is_mptcp = 0; + mptcp_do_fallback(sk); + pr_fallback(mptcp_sk(subflow->conn)); + MPTCP_INC_STATS(sock_net(sk), + MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); } - if (!tp->is_mptcp) + if (mptcp_check_fallback(sk)) return; if (subflow->mp_capable) { pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk), subflow->remote_key); mptcp_finish_connect(sk); - - if (skb) { - pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq); - subflow->ssn_offset = TCP_SKB_CB(skb)->seq; - } } else if (subflow->mp_join) { u8 hmac[SHA256_DIGEST_SIZE]; @@ -286,9 +285,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN); - if (skb) - subflow->ssn_offset = TCP_SKB_CB(skb)->seq; - if (!mptcp_finish_join(sk)) goto do_reset; @@ -564,7 +560,8 @@ enum mapping_status { MAPPING_OK, MAPPING_INVALID, MAPPING_EMPTY, - MAPPING_DATA_FIN + MAPPING_DATA_FIN, + MAPPING_DUMMY }; static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq) @@ -628,6 +625,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk) if (!skb) return MAPPING_EMPTY; + if (mptcp_check_fallback(ssk)) + return MAPPING_DUMMY; + mpext = mptcp_get_ext(skb); if (!mpext || !mpext->use_map) { if (!subflow->map_valid && !skb->len) { @@ -769,6 +769,16 @@ static bool subflow_check_data_avail(struct sock *ssk) ssk->sk_err = EBADMSG; goto fatal; } + if (status == MAPPING_DUMMY) { + __mptcp_do_fallback(msk); + skb = skb_peek(&ssk->sk_receive_queue); + subflow->map_valid = 1; + subflow->map_seq = READ_ONCE(msk->ack_seq); + subflow->map_data_len = skb->len; + subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - + subflow->ssn_offset; + return true; + } if (status != MAPPING_OK) return false; @@ -892,14 +902,18 @@ static void subflow_data_ready(struct sock *sk) { struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); struct sock *parent = subflow->conn; + struct mptcp_sock *msk; - if (!subflow->mp_capable && !subflow->mp_join) { - subflow->tcp_data_ready(sk); - + msk = mptcp_sk(parent); + if (inet_sk_state_load(sk) == TCP_LISTEN) { + set_bit(MPTCP_DATA_READY, &msk->flags); parent->sk_data_ready(parent); return; } + WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable && + !subflow->mp_join); + if (mptcp_subflow_data_available(sk)) mptcp_data_ready(parent, sk); } @@ -1122,7 +1136,7 @@ static void subflow_state_change(struct sock *sk) * a fin packet carrying a DSS can be unnoticed if we don't trigger * the data available machinery here. */ - if (subflow->mp_capable && mptcp_subflow_data_available(sk)) + if (mptcp_subflow_data_available(sk)) mptcp_data_ready(parent, sk); if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
keep using MPTCP sockets and a "dummy mapping" in case of fallback to regular TCP. Skip adding DSS option on send, if TCP fallback has been done earlier. Notes: I'm unsure on what to do in mptcp_clean_una() to do a one-time flush of the retransmit queue, as per Mat's suggestion. Any advice? Changes since v1 - rebase on top of Paolo's fix for NULL dereference in mptcp_recvmsg() Changes since RFC v2: - use a bit in msk->flags, rather than a dedicated boolean in struct msk. This bit is going to be used in combination with another one, TCP_FALLBACK_ALLOWED, that is 1 at the first subflow creation and gets cleared once TCP fallback is no more allowed. - separate code that adds support for "infinite mapping", and use the term "dummy" instead of "infinite". Suggested by Mat - remove inappropriate call to __mptcp_do_fallback() in mptcp_accept() (Paolo) Changes since RFC v1: - use a dedicated member of struct msk to indicate that a fallback ha happened, use it in case of infinite mapping - don't delete skb_ext in case of infinite mapping (Mat) - test the value of pm.subflows on reception of an infinite map to ensure that no other subflow is currently opened (Mat) - in mptcp_established_options(), avoid adding TCP options in case of fallback indication; simplify sendmsg()/recvmsg()/poll() to keep using the MPTCP socket in case of TCP fallback. Set the fallback indication in case subflow is not mp_capable after successful 3-way handshake, instead of flipping 'is_mptcp' (Paolo/Mat) - remove deadcode in mptcp_finish_connect, and increment MPTCP_MIB_MPCAPABLEACTIVEFALLBACK in subflow_finish_connect (Paolo) BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/11 BugLink: https://github.com/multipath-tcp/mptcp_net-next/issues/22 Signed-off-by: Davide Caratti <dcaratti@redhat.com> --- net/mptcp/options.c | 9 ++++- net/mptcp/protocol.c | 78 ++++++++++---------------------------------- net/mptcp/protocol.h | 34 +++++++++++++++++++ net/mptcp/subflow.c | 46 +++++++++++++++++--------- 4 files changed, 90 insertions(+), 77 deletions(-)