mptcp: more DATA FIN fixes

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 <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index afa486912f5a04d9873a042a6ee75cda55fc493e..888bbbbb3e8a40753636a1df89f77eb1d9ddb7d7 100644 (file)
--- 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 5f2fa935022dc26bb869546dea19411554470d0e..6f035af1c9d256ab595f3fccc8c08bdac4dba814 100644 (file)
--- 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.