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authorPaolo Abeni <pabeni@redhat.com>2020-07-03 18:06:04 +0200
committerDavid S. Miller <davem@davemloft.net>2020-07-07 15:27:37 -0700
commit9c29e36152748fd623fcff6cc8f538550f9eeafc (patch)
tree74506d593ba92aa5fd658d16808402dccb08e1c9 /net
parent5eff06902394425c722f0a44d9545909a8800f79 (diff)
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>
Diffstat (limited to 'net')
-rw-r--r--net/mptcp/options.c6
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;
}