mptcp: refine opt_mp_capable determination

OPTIONS_MPTCP_MPC is a combination of three flags.

It would be better to be strict about testing what
flag is expected, at least for code readability.

mptcp_parse_option() already makes the distinction.

- subflow_check_req() should use OPTION_MPTCP_MPC_SYN.

- mptcp_subflow_init_cookie_req() should use OPTION_MPTCP_MPC_ACK.

- subflow_finish_connect() should use OPTION_MPTCP_MPC_SYNACK

- subflow_syn_recv_sock should use OPTION_MPTCP_MPC_ACK

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Fixes: 74c7dfbee3e1 ("mptcp: consolidate in_opt sub-options fields in a bitmask")
Link: https://lore.kernel.org/r/20240111194917.4044654-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 13039ac8d1ab641fb9b22b621ac011e6a7bc9e37..1117d1e84274a5ea1ede990566f67c0073fd86a0 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -157,7 +157,7 @@ static int subflow_check_req(struct request_sock *req,
 
        mptcp_get_options(skb, &mp_opt);
 
-       opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
+       opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
        opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
        if (opt_mp_capable) {
                SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
@@ -254,7 +254,7 @@ int mptcp_subflow_init_cookie_req(struct request_sock *req,
        subflow_init_req(req, sk_listener);
        mptcp_get_options(skb, &mp_opt);
 
-       opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
+       opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
        opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
        if (opt_mp_capable && opt_mp_join)
                return -EINVAL;
@@ -486,7 +486,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 
        mptcp_get_options(skb, &mp_opt);
        if (subflow->request_mptcp) {
-               if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
+               if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
                        MPTCP_INC_STATS(sock_net(sk),
                                        MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
                        mptcp_do_fallback(sk);
@@ -783,7 +783,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
                 * options.
                 */
                mptcp_get_options(skb, &mp_opt);
-               if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC))
+               if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK))
                        fallback = true;
 
        } else if (subflow_req->mp_join) {