mptcp: distinguish rcv vs sent backup flag in requests

When sending an MP_JOIN + SYN + ACK, it is possible to mark the subflow
as 'backup' by setting the flag with the same name. Before this patch,
the backup was set if the other peer set it in its MP_JOIN + SYN
request.

It is not correct: the backup flag should be set in the MPJ+SYN+ACK only
if the host asks for it, and not mirroring what was done by the other
peer. It is then required to have a dedicated bit for each direction,
similar to what is done in the subflow context.

Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 8e8dcfb..8a68382 100644 (file)
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -909,7 +909,7 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
                return true;
        } else if (subflow_req->mp_join) {
                opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
-               opts->backup = subflow_req->backup;
+               opts->backup = subflow_req->request_bkup;
                opts->join_id = subflow_req->local_id;
                opts->thmac = subflow_req->thmac;
                opts->nonce = subflow_req->local_nonce;

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index b11a4e5..b8b2512 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -448,6 +448,7 @@ struct mptcp_subflow_request_sock {
        u16     mp_capable : 1,
                mp_join : 1,
                backup : 1,
+               request_bkup : 1,
                csum_reqd : 1,
                allow_join_id0 : 1;
        u8      local_id;

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 39e2cbd..a3778ae 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -2005,6 +2005,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
                new_ctx->fully_established = 1;
                new_ctx->remote_key_valid = 1;
                new_ctx->backup = subflow_req->backup;
+               new_ctx->request_bkup = subflow_req->request_bkup;
                WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
                new_ctx->token = subflow_req->token;
                new_ctx->thmac = subflow_req->thmac;