tcp: populate inet->cork.fl.u.ip6 in tcp_v6_syn_recv_sock()

As explained in commit 85d05e281712 ("ipv6: change inet6_sk_rebuild_header()
to use inet->cork.fl.u.ip6"):

TCP v6 spends a good amount of time rebuilding a fresh fl6 at each
transmit in inet6_csk_xmit()/inet6_csk_route_socket().

TCP v4 caches the information in inet->cork.fl.u.ip4 instead.

After this patch, passive TCP ipv6 flows have correctly initialized
inet->cork.fl.u.ip6 structure.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260206173426.1638518-7-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
index 745891d2e113707f5c2329cc4c4b14b55c0c7400..ece8dabd209a5b2fb42ec88b9acbc81c01b4174e 100644 (file)
--- a/include/net/inet6_connection_sock.h
+++ b/include/net/inet6_connection_sock.h
@@ -18,7 +18,9 @@ struct sk_buff;
 struct sock;
 struct sockaddr;
 
-struct dst_entry *inet6_csk_route_req(const struct sock *sk, struct flowi6 *fl6,
+struct dst_entry *inet6_csk_route_req(const struct sock *sk,
+                                     struct dst_entry *dst,
+                                     struct flowi6 *fl6,
                                      const struct request_sock *req, u8 proto);
 
 int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);

diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 03e307d5b6b9a2085b1e6b3e3c743795aa16879c..b6c4123aa0aeb803afdf807d8683156b710df2f6 100644 (file)
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -25,6 +25,7 @@
 #include <net/sock_reuseport.h>
 
 struct dst_entry *inet6_csk_route_req(const struct sock *sk,
+                                     struct dst_entry *dst,
                                      struct flowi6 *fl6,
                                      const struct request_sock *req,
                                      u8 proto)
@@ -32,7 +33,6 @@ struct dst_entry *inet6_csk_route_req(const struct sock *sk,
        const struct inet_request_sock *ireq = inet_rsk(req);
        const struct ipv6_pinfo *np = inet6_sk(sk);
        struct in6_addr *final_p, final;
-       struct dst_entry *dst;
 
        memset(fl6, 0, sizeof(*fl6));
        fl6->flowi6_proto = proto;
@@ -48,10 +48,11 @@ struct dst_entry *inet6_csk_route_req(const struct sock *sk,
        fl6->flowi6_uid = sk_uid(sk);
        security_req_classify_flow(req, flowi6_to_flowi_common(fl6));
 
-       dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
-       if (IS_ERR(dst))
-               return NULL;
-
+       if (!dst) {
+               dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
+               if (IS_ERR(dst))
+                       return NULL;
+       }
        return dst;
 }
 

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0fbcb39b3aa709e936a518865e2d16c4027081dd..d10487b4e5bff87d4ff2a7b912a826964101a163 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -539,7 +539,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
        u8 tclass;
 
        /* First, grab a route. */
-       if (!dst && (dst = inet6_csk_route_req(sk, fl6, req,
+       if (!dst && (dst = inet6_csk_route_req(sk, NULL, fl6, req,
                                               IPPROTO_TCP)) == NULL)
                goto done;
 
@@ -789,7 +789,7 @@ static struct dst_entry *tcp_v6_route_req(const struct sock *sk,
        if (security_inet_conn_request(sk, skb, req))
                return NULL;
 
-       return inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
+       return inet6_csk_route_req(sk, NULL, &fl->u.ip6, req, IPPROTO_TCP);
 }
 
 struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
@@ -1318,12 +1318,12 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
                                         struct request_sock *req_unhash,
                                         bool *own_req)
 {
-       struct inet_request_sock *ireq;
-       struct ipv6_pinfo *newnp;
        const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+       struct inet_request_sock *ireq;
        struct ipv6_txoptions *opt;
        struct inet_sock *newinet;
        bool found_dup_sk = false;
+       struct ipv6_pinfo *newnp;
        struct tcp_sock *newtp;
        struct sock *newsk;
 #ifdef CONFIG_TCP_MD5SIG
@@ -1392,11 +1392,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
        if (sk_acceptq_is_full(sk))
                goto exit_overflow;
 
-       if (!dst) {
-               dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
-               if (!dst)
-                       goto exit;
-       }
+       dst = inet6_csk_route_req(sk, dst, &fl6, req, IPPROTO_TCP);
+       if (!dst)
+               goto exit;
 
        newsk = tcp_create_openreq_child(sk, req, skb);
        if (!newsk)
@@ -1412,6 +1410,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
        inet6_sk_rx_dst_set(newsk, skb);
 
        newinet = inet_sk(newsk);
+       newinet->cork.fl.u.ip6 = fl6;
        newinet->pinet6 = tcp_inet6_sk(newsk);
        newinet->ipv6_fl_list = NULL;
        newinet->inet_opt = NULL;