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| author |   Paolo Abeni <pabeni@redhat.com> | 2020-03-04 16:51:07 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2020-03-05 21:34:42 -0800 |
| commit | 2398e3991bda7caa6b112a6f650fbab92f732b91 (patch) | |
| tree | 57236049c35a02f7a728e5aa499bbd33931c9528 | |
| parent | net: nfc: fix bounds checking bugs on "pipe" (diff) | |
| download | linux-dev-2398e3991bda7caa6b112a6f650fbab92f732b91.tar.xz linux-dev-2398e3991bda7caa6b112a6f650fbab92f732b91.zip | |
mptcp: always include dack if possible.
Currently passive MPTCP socket can skip including the DACK
option - if the peer sends data before accept() completes.
The above happens because the msk 'can_ack' flag is set
only after the accept() call.
Such missing DACK option may cause - as per RFC spec -
unwanted fallback to TCP.
This change addresses the issue using the key material
available in the current subflow, if any, to create a suitable
dack option when msk ack seq is not yet available.
v1 -> v2:
- adavance the generated ack after the initial MPC packet
Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/mptcp/options.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 45acd877bef3..fd2c3150e591 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -334,6 +334,8 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, struct mptcp_sock *msk; unsigned int ack_size; bool ret = false; + bool can_ack; + u64 ack_seq; u8 tcp_fin; if (skb) { @@ -360,9 +362,22 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, ret = true; } + /* passive sockets msk will set the 'can_ack' after accept(), even + * if the first subflow may have the already the remote key handy + */ + can_ack = true; opts->ext_copy.use_ack = 0; msk = mptcp_sk(subflow->conn); - if (!msk || !READ_ONCE(msk->can_ack)) { + if (likely(msk && READ_ONCE(msk->can_ack))) { + ack_seq = msk->ack_seq; + } else if (subflow->can_ack) { + mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq); + ack_seq++; + } else { + can_ack = false; + } + + if (unlikely(!can_ack)) { *size = ALIGN(dss_size, 4); return ret; } @@ -375,7 +390,7 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, dss_size += ack_size; - opts->ext_copy.data_ack = msk->ack_seq; + opts->ext_copy.data_ack = ack_seq; opts->ext_copy.ack64 = 1; opts->ext_copy.use_ack = 1; |