@@ -1224,20 +1224,58 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
return true;
}
-static void mptcp_set_rwin(const struct tcp_sock *tp)
+static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th)
{
const struct sock *ssk = (const struct sock *)tp;
- const struct mptcp_subflow_context *subflow;
+ struct mptcp_subflow_context *subflow;
+ u64 ack_seq, rcv_wnd_old, rcv_wnd_new;
struct mptcp_sock *msk;
- u64 ack_seq;
+ u32 new_win;
+ u64 win;
subflow = mptcp_subflow_ctx(ssk);
msk = mptcp_sk(subflow->conn);
- ack_seq = READ_ONCE(msk->ack_seq) + tp->rcv_wnd;
+ ack_seq = READ_ONCE(msk->ack_seq);
+ rcv_wnd_new = ack_seq + tp->rcv_wnd;
+
+ rcv_wnd_old = READ_ONCE(msk->rcv_wnd_sent);
+ if (after64(rcv_wnd_new, rcv_wnd_old)) {
+ u64 rcv_wnd;
+
+ for (;;) {
+ rcv_wnd = cmpxchg64(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new);
+
+ if (rcv_wnd == rcv_wnd_old)
+ break;
+ if (before64(rcv_wnd_new, rcv_wnd))
+ goto raise_win;
+ rcv_wnd_old = rcv_wnd;
+ };
+ return;
+ }
+
+ if (rcv_wnd_new != rcv_wnd_old) {
+raise_win:
+ win = rcv_wnd_old - ack_seq;
+ tp->rcv_wnd = min_t(u64, win, U32_MAX);
+ new_win = tp->rcv_wnd;
- if (after64(ack_seq, READ_ONCE(msk->rcv_wnd_sent)))
- WRITE_ONCE(msk->rcv_wnd_sent, ack_seq);
+ /* Make sure we do not exceed the maximum possible
+ * scaled window.
+ */
+ if (unlikely(th->syn))
+ new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale;
+ if (!tp->rx_opt.rcv_wscale &&
+ sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)
+ new_win = min(new_win, MAX_TCP_WINDOW);
+ else
+ new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
+
+ /* RFC1323 scaling applied */
+ new_win >>= tp->rx_opt.rcv_wscale;
+ th->window = htons(new_win);
+ }
}
u16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum)
@@ -1550,7 +1588,7 @@ void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp,
}
if (tp)
- mptcp_set_rwin(tp);
+ mptcp_set_rwin(tp, th);
}
__be32 mptcp_get_reset_option(const struct sk_buff *skb)
As per RFC, the offered MPTCP-level window should never shrink. While we currently track the right edge, we don't enforce the above constraint on the wire. Additionally, concurrent xmit on different subflows can end-up in erroneous right edge update. Address the above explicitly updating the announced window and protecting the update with an additional atomic operation (sic) Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/mptcp/options.c | 52 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 45 insertions(+), 7 deletions(-)