* [PATCH net v2] mptcp: always include dack if possible.
@ 2020-03-04 15:51 Paolo Abeni
2020-03-05 1:07 ` Mat Martineau
2020-03-06 5:35 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Paolo Abeni @ 2020-03-04 15:51 UTC (permalink / raw)
To: netdev; +Cc: Mat Martineau, Matthieu Baerts, David S. Miller, Christoph Paasch
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>
---
net/mptcp/options.c | 19 +++++++++++++++++--
1 file 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;
--
2.21.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net v2] mptcp: always include dack if possible.
2020-03-04 15:51 [PATCH net v2] mptcp: always include dack if possible Paolo Abeni
@ 2020-03-05 1:07 ` Mat Martineau
2020-03-06 5:35 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Mat Martineau @ 2020-03-05 1:07 UTC (permalink / raw)
To: Paolo Abeni; +Cc: netdev, Matthieu Baerts, David S. Miller, Christoph Paasch
On Wed, 4 Mar 2020, Paolo Abeni wrote:
> 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>
--
Mat Martineau
Intel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net v2] mptcp: always include dack if possible.
2020-03-04 15:51 [PATCH net v2] mptcp: always include dack if possible Paolo Abeni
2020-03-05 1:07 ` Mat Martineau
@ 2020-03-06 5:35 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2020-03-06 5:35 UTC (permalink / raw)
To: pabeni; +Cc: netdev, mathew.j.martineau, matthieu.baerts, cpaasch
From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 4 Mar 2020 16:51:07 +0100
> 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>
Applied, thank you.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-03-06 5:35 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-03-04 15:51 [PATCH net v2] mptcp: always include dack if possible Paolo Abeni
2020-03-05 1:07 ` Mat Martineau
2020-03-06 5:35 ` David Miller
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).