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 8e8dcfbc299382454cf715a917c0f876ad5c35d4..8a68382a4fe9104c9bdd787669b801dc868e3973 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 b11a4e50d52b6f1950660654eee022d387b6dc4b..b8b25124e7def07a2bf34110ebedc210fb672344 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 39e2cbdf38019cc99e31e54ac221dbc7ef825110..a3778aee4e77f8dadc0b32500ee976a65aef8f86 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;