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| author | Paolo Abeni <pabeni@redhat.com> | 2020-07-03 18:06:04 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-07 15:27:37 -0700 |
| commit | 9c29e36152748fd623fcff6cc8f538550f9eeafc (patch) | |
| tree | 74506d593ba92aa5fd658d16808402dccb08e1c9 | |
| parent | 5eff06902394425c722f0a44d9545909a8800f79 (diff) | |
| download | linux-9c29e36152748fd623fcff6cc8f538550f9eeafc.tar.bz2 | |
mptcp: fix DSS map generation on fin retransmission
The RFC 8684 mandates that no-data DATA FIN packets should carry
a DSS with 0 sequence number and data len equal to 1. Currently,
on FIN retransmission we re-use the existing mapping; if the previous
fin transmission was part of a partially acked data packet, we could
end-up writing in the egress packet a non-compliant DSS.
The above will be detected by a "Bad mapping" warning on the receiver
side.
This change addresses the issue explicitly checking for 0 len packet
when adding the DATA_FIN option.
Fixes: 6d0060f600ad ("mptcp: Write MPTCP DSS headers to outgoing data packets")
Reported-by: syzbot+42a07faa5923cfaeb9c9@syzkaller.appspotmail.com
Tested-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/mptcp/options.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c index df9a51425c6f..8f940be42f98 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -449,9 +449,9 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, } static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow, - struct mptcp_ext *ext) + struct sk_buff *skb, struct mptcp_ext *ext) { - if (!ext->use_map) { + if (!ext->use_map || !skb->len) { /* RFC6824 requires a DSS mapping with specific values * if DATA_FIN is set but no data payload is mapped */ @@ -503,7 +503,7 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb, opts->ext_copy = *mpext; if (skb && tcp_fin && subflow->data_fin_tx_enable) - mptcp_write_data_fin(subflow, &opts->ext_copy); + mptcp_write_data_fin(subflow, skb, &opts->ext_copy); ret = true; } |