2 files changed, 36 insertions, 0 deletions

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 6ac4e3b5007f..4367d913c0e2 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -250,6 +250,9 @@ extern int inet_csk_get_port(struct sock *sk, unsigned short snum);
 
 extern struct dst_entry* inet_csk_route_req(struct sock *sk,
                                             const struct request_sock *req);
+extern struct dst_entry* inet_csk_route_child_sock(struct sock *sk,
+                                                   struct sock *newsk,
+                                                   const struct request_sock *req);
 
 static inline void inet_csk_reqsk_queue_add(struct sock *sk,
                                             struct request_sock *req,
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 54944da2f794..3a2ba5632dff 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -379,6 +379,39 @@ no_route:
 }
 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 
+struct dst_entry *inet_csk_route_child_sock(struct sock *sk,
+                                            struct sock *newsk,
+                                            const struct request_sock *req)
+{
+        const struct inet_request_sock *ireq = inet_rsk(req);
+        struct inet_sock *newinet = inet_sk(newsk);
+        struct ip_options_rcu *opt = ireq->opt;
+        struct net *net = sock_net(sk);
+        struct flowi4 *fl4;
+        struct rtable *rt;
+
+        fl4 = &newinet->cork.fl.u.ip4;
+        flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
+                           RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
+                           sk->sk_protocol, inet_sk_flowi_flags(sk),
+                           (opt && opt->opt.srr) ? opt->opt.faddr : ireq->rmt_addr,
+                           ireq->loc_addr, ireq->rmt_port, inet_sk(sk)->inet_sport);
+        security_req_classify_flow(req, flowi4_to_flowi(fl4));
+        rt = ip_route_output_flow(net, fl4, sk);
+        if (IS_ERR(rt))
+                goto no_route;
+        if (opt && opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
+                goto route_err;
+        return &rt->dst;
+
+route_err:
+        ip_rt_put(rt);
+no_route:
+        IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
+
 static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
                                  const u32 rnd, const u32 synq_hsize)
 {