[PATCH net-next v9 5/7] mptcp: support rstreason for passive reset

[Jason Xing]

From: Jason Xing <kernelx...@tencent.com>

It relies on what reset options in the skb are as rfc8684 says. Reusing
this logic can save us much energy. This patch replaces most of the prior
NOT_SPECIFIED reasons.

Signed-off-by: Jason Xing <kernelx...@tencent.com>
Reviewed-by: Matthieu Baerts (NGI0) <matt...@kernel.org>
---
 net/mptcp/protocol.h | 27 +++++++++++++++++++++++++++
 net/mptcp/subflow.c  | 22 +++++++++++++++++-----
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index fdfa843e2d88..252618859ee8 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -581,6 +581,33 @@ mptcp_subflow_ctx_reset(struct mptcp_subflow_context 
*subflow)
        WRITE_ONCE(subflow->local_id, -1);
 }
 
+/* Convert reset reasons in MPTCP to enum sk_rst_reason type */
+static inline enum sk_rst_reason
+sk_rst_convert_mptcp_reason(u32 reason)
+{
+       switch (reason) {
+       case MPTCP_RST_EUNSPEC:
+               return SK_RST_REASON_MPTCP_RST_EUNSPEC;
+       case MPTCP_RST_EMPTCP:
+               return SK_RST_REASON_MPTCP_RST_EMPTCP;
+       case MPTCP_RST_ERESOURCE:
+               return SK_RST_REASON_MPTCP_RST_ERESOURCE;
+       case MPTCP_RST_EPROHIBIT:
+               return SK_RST_REASON_MPTCP_RST_EPROHIBIT;
+       case MPTCP_RST_EWQ2BIG:
+               return SK_RST_REASON_MPTCP_RST_EWQ2BIG;
+       case MPTCP_RST_EBADPERF:
+               return SK_RST_REASON_MPTCP_RST_EBADPERF;
+       case MPTCP_RST_EMIDDLEBOX:
+               return SK_RST_REASON_MPTCP_RST_EMIDDLEBOX;
+       default:
+               /* It should not happen, or else errors may occur
+                * in MPTCP layer
+                */
+               return SK_RST_REASON_ERROR;
+       }
+}
+
 static inline u64
 mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
 {
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index ac867d277860..fb7abf2d01ca 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -309,8 +309,13 @@ static struct dst_entry *subflow_v4_route_req(const struct 
sock *sk,
                return dst;
 
        dst_release(dst);
-       if (!req->syncookie)
-               tcp_request_sock_ops.send_reset(sk, skb, 
SK_RST_REASON_NOT_SPECIFIED);
+       if (!req->syncookie) {
+               struct mptcp_ext *mpext = mptcp_get_ext(skb);
+               enum sk_rst_reason reason;
+
+               reason = sk_rst_convert_mptcp_reason(mpext->reset_reason);
+               tcp_request_sock_ops.send_reset(sk, skb, reason);
+       }
        return NULL;
 }
 
@@ -377,8 +382,13 @@ static struct dst_entry *subflow_v6_route_req(const struct 
sock *sk,
                return dst;
 
        dst_release(dst);
-       if (!req->syncookie)
-               tcp6_request_sock_ops.send_reset(sk, skb, 
SK_RST_REASON_NOT_SPECIFIED);
+       if (!req->syncookie) {
+               struct mptcp_ext *mpext = mptcp_get_ext(skb);
+               enum sk_rst_reason reason;
+
+               reason = sk_rst_convert_mptcp_reason(mpext->reset_reason);
+               tcp6_request_sock_ops.send_reset(sk, skb, reason);
+       }
        return NULL;
 }
 #endif
@@ -783,6 +793,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock 
*sk,
        struct mptcp_subflow_request_sock *subflow_req;
        struct mptcp_options_received mp_opt;
        bool fallback, fallback_is_fatal;
+       enum sk_rst_reason reason;
        struct mptcp_sock *owner;
        struct sock *child;
 
@@ -913,7 +924,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock 
*sk,
        tcp_rsk(req)->drop_req = true;
        inet_csk_prepare_for_destroy_sock(child);
        tcp_done(child);
-       req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+       reason = sk_rst_convert_mptcp_reason(mptcp_get_ext(skb)->reset_reason);
+       req->rsk_ops->send_reset(sk, skb, reason);
 
        /* The last child reference will be released by the caller */
        return child;
-- 
2.37.3