Currently data fin on data packet are not handled properly:
the 'rcv_data_fin_seq' field is interpreted as the last
sequence number carrying a valid data, but for data fin
packet with valid maps we currently store map_seq + map_len,
that is, the next value.
The 'write_seq' fields carries instead the value subseguent
to the last valid byte, so in mptcp_write_data_fin() we
never detect correctly the last DSS map.
Fixes: 7279da6145bb ("mptcp: Use MPTCP-level flag for sending DATA_FIN")
Fixes: 1a49b2c2a501 ("mptcp: Handle incoming 32-bit DATA_FIN values")
Reviewed-by: Mat Martineau <mathew.j.martin...@linux.intel.com>
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
net/mptcp/options.c | 10 +++++-----
net/mptcp/subflow.c | 2 +-
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index afa486912f5a..888bbbbb3e8a 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -451,7 +451,10 @@ 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 sk_buff *skb, struct mptcp_ext *ext)
{
- u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq);
+ /* The write_seq value has already been incremented, so the actual
+ * sequence number for the DATA_FIN is one less.
+ */
+ u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
if (!ext->use_map || !skb->len) {
/* RFC6824 requires a DSS mapping with specific values
@@ -460,10 +463,7 @@ static void mptcp_write_data_fin(struct
mptcp_subflow_context *subflow,
ext->data_fin = 1;
ext->use_map = 1;
ext->dsn64 = 1;
- /* The write_seq value has already been incremented, so
- * the actual sequence number for the DATA_FIN is one less.
- */
- ext->data_seq = data_fin_tx_seq - 1;
+ ext->data_seq = data_fin_tx_seq;
ext->subflow_seq = 0;
ext->data_len = 1;
} else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 5f2fa935022d..6f035af1c9d2 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -749,7 +749,7 @@ static enum mapping_status get_mapping_status(struct sock
*ssk,
return MAPPING_DATA_FIN;
}
} else {
- u64 data_fin_seq = mpext->data_seq + data_len;
+ u64 data_fin_seq = mpext->data_seq + data_len - 1;
/* If mpext->data_seq is a 32-bit value, data_fin_seq
* must also be limited to 32 bits.
--
2.26.2
