mptcp: consolidate initial ack seq generation

Currently the initial ack sequence is generated on demand whenever
it's requested and the remote key is handy. The relevant code is
scattered in different places and can lead to multiple, unneeded,
crypto operations.

This change consolidates the ack sequence generation code in a single
helper, storing the sequence number at the subflow level.

The above additionally saves a few conditional in fast-path and will
simplify the upcoming fast-open implementation.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 784a205e80dab0352dfaa18c83033ff7f5c27107..ae076468fcb9ab79502e7505cabef3da05c3b396 100644 (file)
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -953,8 +953,9 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
                return subflow->mp_capable;
        }
 
-       if (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||
-           ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo)) {
+       if (subflow->remote_key_valid &&
+           (((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||
+            ((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo))) {
                /* subflows are fully established as soon as we get any
                 * additional ack, including ADD_ADDR.
                 */

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index efc84816a692914fbd75500d867b5a132ef96c26..66a599d2ee1948b79bc617941b72ef75643fec2e 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3045,7 +3045,6 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
        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;
@@ -3071,15 +3070,6 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
        msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
        msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
 
-       if (mp_opt->suboptions & OPTIONS_MPTCP_MPC) {
-               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);
-               atomic64_set(&msk->rcv_wnd_sent, 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);
@@ -3352,7 +3342,6 @@ 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;
@@ -3360,22 +3349,16 @@ void mptcp_finish_connect(struct sock *ssk)
 
        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_seq = subflow->iasn;
        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->snd_nxt, msk->write_seq);
-       WRITE_ONCE(msk->ack_seq, ack_seq);
-       WRITE_ONCE(msk->can_ack, 1);
        WRITE_ONCE(msk->snd_una, msk->write_seq);
-       atomic64_set(&msk->rcv_wnd_sent, ack_seq);
 
        mptcp_pm_new_connection(msk, ssk, 0);
 

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 6a09ab99a12de9d56f97c6c009a46ff3b059953f..b5abea3d1a9c006a9262c6a491a6ad6ee921df9e 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -467,7 +467,7 @@ struct mptcp_subflow_context {
                send_fastclose : 1,
                send_infinite_map : 1,
                rx_eof : 1,
-               can_ack : 1,        /* only after processing the remote a key */
+               remote_key_valid : 1,        /* received the peer key from */
                disposable : 1,     /* ctx can be free at ulp release time */
                stale : 1,          /* unable to snd/rcv data, do not use for xmit */
                local_id_valid : 1, /* local_id is correctly initialized */
@@ -477,7 +477,10 @@ struct mptcp_subflow_context {
        u64     thmac;
        u32     local_nonce;
        u32     remote_token;
-       u8      hmac[MPTCPOPT_HMAC_LEN];
+       union {
+               u8      hmac[MPTCPOPT_HMAC_LEN]; /* MPJ subflow only */
+               u64     iasn;       /* initial ack sequence number, MPC subflows only */
+       };
        u8      local_id;
        u8      remote_id;
        u8      reset_seen:1;
@@ -603,7 +606,7 @@ unsigned int mptcp_stale_loss_cnt(const struct net *net);
 int mptcp_get_pm_type(const struct net *net);
 void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
-                                    struct mptcp_options_received *mp_opt);
+                                    const struct mptcp_options_received *mp_opt);
 bool __mptcp_retransmit_pending_data(struct sock *sk);
 void mptcp_check_and_set_pending(struct sock *sk);
 void __mptcp_push_pending(struct sock *sk, unsigned int flags);

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index f3c336872475e87e1df131571f04fad00dde6770..eca4de08ca9c0a95d837ab00bff1e9c6148db0f3 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -392,11 +392,33 @@ static void mptcp_set_connected(struct sock *sk)
        mptcp_data_unlock(sk);
 }
 
+static void subflow_set_remote_key(struct mptcp_sock *msk,
+                                  struct mptcp_subflow_context *subflow,
+                                  const struct mptcp_options_received *mp_opt)
+{
+       /* active MPC subflow will reach here multiple times:
+        * at subflow_finish_connect() time and at 4th ack time
+        */
+       if (subflow->remote_key_valid)
+               return;
+
+       subflow->remote_key_valid = 1;
+       subflow->remote_key = mp_opt->sndr_key;
+       mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
+       subflow->iasn++;
+
+       WRITE_ONCE(msk->remote_key, subflow->remote_key);
+       WRITE_ONCE(msk->ack_seq, subflow->iasn);
+       WRITE_ONCE(msk->can_ack, true);
+       atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
+}
+
 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 mptcp_sock *msk;
 
        subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 
@@ -404,6 +426,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
        if (subflow->conn_finished)
                return;
 
+       msk = mptcp_sk(parent);
        mptcp_propagate_sndbuf(parent, sk);
        subflow->rel_write_seq = 1;
        subflow->conn_finished = 1;
@@ -416,19 +439,16 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
                        MPTCP_INC_STATS(sock_net(sk),
                                        MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
                        mptcp_do_fallback(sk);
-                       pr_fallback(mptcp_sk(subflow->conn));
+                       pr_fallback(msk);
                        goto fallback;
                }
 
                if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
-                       WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
+                       WRITE_ONCE(msk->csum_enabled, true);
                if (mp_opt.deny_join_id0)
-                       WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
+                       WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
                subflow->mp_capable = 1;
-               subflow->can_ack = 1;
-               subflow->remote_key = mp_opt.sndr_key;
-               pr_debug("subflow=%p, remote_key=%llu", subflow,
-                        subflow->remote_key);
+               subflow_set_remote_key(msk, subflow, &mp_opt);
                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
                mptcp_finish_connect(sk);
                mptcp_set_connected(parent);
@@ -466,7 +486,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
                subflow->mp_join = 1;
                MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 
-               if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
+               if (subflow_use_different_dport(msk, sk)) {
                        pr_debug("synack inet_dport=%d %d",
                                 ntohs(inet_sk(sk)->inet_dport),
                                 ntohs(inet_sk(parent)->inet_dport));
@@ -474,7 +494,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
                }
        } else if (mptcp_check_fallback(sk)) {
 fallback:
-               mptcp_rcv_space_init(mptcp_sk(parent), sk);
+               mptcp_rcv_space_init(msk, sk);
                mptcp_set_connected(parent);
        }
        return;
@@ -637,13 +657,12 @@ static void subflow_drop_ctx(struct sock *ssk)
 }
 
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
-                                    struct mptcp_options_received *mp_opt)
+                                    const struct mptcp_options_received *mp_opt)
 {
        struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 
-       subflow->remote_key = mp_opt->sndr_key;
+       subflow_set_remote_key(msk, subflow, mp_opt);
        subflow->fully_established = 1;
-       subflow->can_ack = 1;
        WRITE_ONCE(msk->fully_established, true);
 }
 
@@ -1198,16 +1217,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
                if (WARN_ON_ONCE(!skb))
                        goto no_data;
 
-               /* if msk lacks the remote key, this subflow must provide an
-                * MP_CAPABLE-based mapping
-                */
-               if (unlikely(!READ_ONCE(msk->can_ack))) {
-                       if (!subflow->mpc_map)
-                               goto fallback;
-                       WRITE_ONCE(msk->remote_key, subflow->remote_key);
-                       WRITE_ONCE(msk->ack_seq, subflow->map_seq);
-                       WRITE_ONCE(msk->can_ack, true);
-               }
+               if (unlikely(!READ_ONCE(msk->can_ack)))
+                       goto fallback;
 
                old_ack = READ_ONCE(msk->ack_seq);
                ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
@@ -1480,6 +1491,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 
        mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
                                             &flags, &ifindex);
+       subflow->remote_key_valid = 1;
        subflow->remote_key = msk->remote_key;
        subflow->local_key = msk->local_key;
        subflow->token = msk->token;
@@ -1873,6 +1885,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
                new_ctx->ssn_offset = subflow_req->ssn_offset;
                new_ctx->mp_join = 1;
                new_ctx->fully_established = 1;
+               new_ctx->remote_key_valid = 1;
                new_ctx->backup = subflow_req->backup;
                new_ctx->remote_id = subflow_req->remote_id;
                new_ctx->token = subflow_req->token;