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mptcp: update per unacked sequence on pkt reception

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So that we keep per unacked sequence number consistent; since
we update per msk data, use an atomic64 cmpxchg() to protect
against concurrent updates from multiple subflows.

Initialize the snd_una at connect()/accept() time.

Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2020-03-27 14:48:42 -07:00 committed by David S. Miller
parent 926bdeab55
commit cc9d256698
3 changed files with 49 additions and 6 deletions
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52
net/mptcp/options.c
View File

@ -744,6 +744,46 @@ fully_established:
return true;
}
static u64 expand_ack(u64 old_ack, u64 cur_ack, bool use_64bit)
{
u32 old_ack32, cur_ack32;
if (use_64bit)
return cur_ack;
old_ack32 = (u32)old_ack;
cur_ack32 = (u32)cur_ack;
cur_ack = (old_ack & GENMASK_ULL(63, 32)) + cur_ack32;
if (unlikely(before(cur_ack32, old_ack32)))
return cur_ack + (1LL << 32);
return cur_ack;
}
static void update_una(struct mptcp_sock *msk,
struct mptcp_options_received *mp_opt)
{
u64 new_snd_una, snd_una, old_snd_una = atomic64_read(&msk->snd_una);
u64 write_seq = READ_ONCE(msk->write_seq);
/* avoid ack expansion on update conflict, to reduce the risk of
* wrongly expanding to a future ack sequence number, which is way
* more dangerous than missing an ack
*/
new_snd_una = expand_ack(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
/* ACK for data not even sent yet? Ignore. */
if (after64(new_snd_una, write_seq))
new_snd_una = old_snd_una;
while (after64(new_snd_una, old_snd_una)) {
snd_una = old_snd_una;
old_snd_una = atomic64_cmpxchg(&msk->snd_una, snd_una,
new_snd_una);
if (old_snd_una == snd_una)
break;
}
}
static bool add_addr_hmac_valid(struct mptcp_sock *msk,
struct mptcp_options_received *mp_opt)
{
@ -805,6 +845,12 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
if (!mp_opt->dss)
return;
/* we can't wait for recvmsg() to update the ack_seq, otherwise
* monodirectional flows will stuck
*/
if (mp_opt->use_ack)
update_una(msk, mp_opt);
mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
if (!mpext)
return;
@ -831,12 +877,6 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
mpext->use_map = 1;
}
if (mp_opt->use_ack) {
mpext->data_ack = mp_opt->data_ack;
mpext->use_ack = 1;
mpext->ack64 = mp_opt->ack64;
}
mpext->data_fin = mp_opt->data_fin;
}

2
net/mptcp/protocol.c
View File

@ -906,6 +906,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk, struct request_sock *req)
}
msk->write_seq = subflow_req->idsn + 1;
atomic64_set(&msk->snd_una, msk->write_seq);
if (subflow_req->remote_key_valid) {
msk->can_ack = true;
msk->remote_key = subflow_req->remote_key;
@ -1107,6 +1108,7 @@ void mptcp_finish_connect(struct sock *ssk)
WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
WRITE_ONCE(msk->ack_seq, ack_seq);
WRITE_ONCE(msk->can_ack, 1);
atomic64_set(&msk->snd_una, msk->write_seq);
mptcp_pm_new_connection(msk, 0);
}

1
net/mptcp/protocol.h
View File

@ -147,6 +147,7 @@ struct mptcp_sock {
u64 remote_key;
u64 write_seq;
u64 ack_seq;
atomic64_t snd_una;
u32 token;
unsigned long flags;
bool can_ack;