l2tp: Use inet_sk_init_flowi4() in l2tp_ip_sendmsg().

Use inet_sk_init_flowi4() to automatically initialise the flowi4
structure in l2tp_ip_sendmsg() instead of passing parameters manually
to ip_route_output_ports().

Override ->daddr with the value passed in the msghdr structure if
provided.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: James Chapman <jchapman@katalix.com>
Link: https://patch.msgid.link/2ff22a3560c5050228928456662b80b9c84a8fe4.1734357769.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 4bc24fddfd52424b08cb78bc0125a3e698021e8c..29795d2839e8b00ece63e6e71fa83d53e34f9dda 100644 (file)
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -425,7 +425,6 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        int rc;
        struct inet_sock *inet = inet_sk(sk);
        struct rtable *rt = NULL;
-       struct flowi4 *fl4;
        int connected = 0;
        __be32 daddr;
 
@@ -455,7 +454,6 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                if (sk->sk_state != TCP_ESTABLISHED)
                        goto out;
 
-               daddr = inet->inet_daddr;
                connected = 1;
        }
 
@@ -482,29 +480,24 @@ static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                goto error;
        }
 
-       fl4 = &inet->cork.fl.u.ip4;
        if (connected)
                rt = dst_rtable(__sk_dst_check(sk, 0));
 
        rcu_read_lock();
        if (!rt) {
-               const struct ip_options_rcu *inet_opt;
+               struct flowi4 *fl4 = &inet->cork.fl.u.ip4;
 
-               inet_opt = rcu_dereference(inet->inet_opt);
+               inet_sk_init_flowi4(inet, fl4);
 
-               /* Use correct destination address if we have options. */
-               if (inet_opt && inet_opt->opt.srr)
-                       daddr = inet_opt->opt.faddr;
+               /* Overwrite ->daddr if msg->msg_name was provided */
+               if (!connected)
+                       fl4->daddr = daddr;
 
                /* If this fails, retransmit mechanism of transport layer will
                 * keep trying until route appears or the connection times
                 * itself out.
                 */
-               rt = ip_route_output_ports(sock_net(sk), fl4, sk,
-                                          daddr, inet->inet_saddr,
-                                          inet->inet_dport, inet->inet_sport,
-                                          sk->sk_protocol, ip_sock_rt_tos(sk),
-                                          sk->sk_bound_dev_if);
+               rt = ip_route_output_flow(sock_net(sk), fl4, sk);
                if (IS_ERR(rt))
                        goto no_route;
                if (connected) {