l2tp: cleanup netlink send of tunnel address information

l2tp_nl_tunnel_send has conditionally compiled code to support AF_INET6,
which makes the code difficult to follow and triggers checkpatch
warnings.

Split the code out into functions to handle the AF_INET v.s. AF_INET6
cases, which both improves readability and resolves the checkpatch
warnings.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index fc26eba..0021cc0 100644 (file)
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -310,16 +310,79 @@ out:
        return ret;
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+static int l2tp_nl_tunnel_send_addr6(struct sk_buff *skb, struct sock *sk,
+                                    enum l2tp_encap_type encap)
+{
+       struct inet_sock *inet = inet_sk(sk);
+       struct ipv6_pinfo *np = inet6_sk(sk);
+
+       switch (encap) {
+       case L2TP_ENCAPTYPE_UDP:
+               if (udp_get_no_check6_tx(sk) &&
+                   nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_TX))
+                       return -1;
+               if (udp_get_no_check6_rx(sk) &&
+                   nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_RX))
+                       return -1;
+               if (nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
+                   nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
+                       return -1;
+               fallthrough;
+       case L2TP_ENCAPTYPE_IP:
+               if (nla_put_in6_addr(skb, L2TP_ATTR_IP6_SADDR, &np->saddr) ||
+                   nla_put_in6_addr(skb, L2TP_ATTR_IP6_DADDR, &sk->sk_v6_daddr))
+                       return -1;
+               break;
+       }
+       return 0;
+}
+#endif
+
+static int l2tp_nl_tunnel_send_addr4(struct sk_buff *skb, struct sock *sk,
+                                    enum l2tp_encap_type encap)
+{
+       struct inet_sock *inet = inet_sk(sk);
+
+       switch (encap) {
+       case L2TP_ENCAPTYPE_UDP:
+               if (nla_put_u8(skb, L2TP_ATTR_UDP_CSUM, !sk->sk_no_check_tx) ||
+                   nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
+                   nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
+                       return -1;
+               fallthrough;
+       case L2TP_ENCAPTYPE_IP:
+               if (nla_put_in_addr(skb, L2TP_ATTR_IP_SADDR, inet->inet_saddr) ||
+                   nla_put_in_addr(skb, L2TP_ATTR_IP_DADDR, inet->inet_daddr))
+                       return -1;
+               break;
+       }
+
+       return 0;
+}
+
+/* Append attributes for the tunnel address, handling the different attribute types
+ * used for different tunnel encapsulation and AF_INET v.s. AF_INET6.
+ */
+static int l2tp_nl_tunnel_send_addr(struct sk_buff *skb, struct l2tp_tunnel *tunnel)
+{
+       struct sock *sk = tunnel->sock;
+
+       if (!sk)
+               return 0;
+
+#if IS_ENABLED(CONFIG_IPV6)
+       if (sk->sk_family == AF_INET6)
+               return l2tp_nl_tunnel_send_addr6(skb, sk, tunnel->encap);
+#endif
+       return l2tp_nl_tunnel_send_addr4(skb, sk, tunnel->encap);
+}
+
 static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int flags,
                               struct l2tp_tunnel *tunnel, u8 cmd)
 {
        void *hdr;
        struct nlattr *nest;
-       struct sock *sk = NULL;
-       struct inet_sock *inet;
-#if IS_ENABLED(CONFIG_IPV6)
-       struct ipv6_pinfo *np = NULL;
-#endif
 
        hdr = genlmsg_put(skb, portid, seq, &l2tp_nl_family, flags, cmd);
        if (!hdr)
@@ -363,58 +426,9 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 portid, u32 seq, int fla
                goto nla_put_failure;
        nla_nest_end(skb, nest);
 
-       sk = tunnel->sock;
-       if (!sk)
-               goto out;
-
-#if IS_ENABLED(CONFIG_IPV6)
-       if (sk->sk_family == AF_INET6)
-               np = inet6_sk(sk);
-#endif
-
-       inet = inet_sk(sk);
-
-       switch (tunnel->encap) {
-       case L2TP_ENCAPTYPE_UDP:
-               switch (sk->sk_family) {
-               case AF_INET:
-                       if (nla_put_u8(skb, L2TP_ATTR_UDP_CSUM, !sk->sk_no_check_tx))
-                               goto nla_put_failure;
-                       break;
-#if IS_ENABLED(CONFIG_IPV6)
-               case AF_INET6:
-                       if (udp_get_no_check6_tx(sk) &&
-                           nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_TX))
-                               goto nla_put_failure;
-                       if (udp_get_no_check6_rx(sk) &&
-                           nla_put_flag(skb, L2TP_ATTR_UDP_ZERO_CSUM6_RX))
-                               goto nla_put_failure;
-                       break;
-#endif
-               }
-               if (nla_put_u16(skb, L2TP_ATTR_UDP_SPORT, ntohs(inet->inet_sport)) ||
-                   nla_put_u16(skb, L2TP_ATTR_UDP_DPORT, ntohs(inet->inet_dport)))
-                       goto nla_put_failure;
-               /* fall through  */
-       case L2TP_ENCAPTYPE_IP:
-#if IS_ENABLED(CONFIG_IPV6)
-               if (np) {
-                       if (nla_put_in6_addr(skb, L2TP_ATTR_IP6_SADDR,
-                                            &np->saddr) ||
-                           nla_put_in6_addr(skb, L2TP_ATTR_IP6_DADDR,
-                                            &sk->sk_v6_daddr))
-                               goto nla_put_failure;
-               } else
-#endif
-               if (nla_put_in_addr(skb, L2TP_ATTR_IP_SADDR,
-                                   inet->inet_saddr) ||
-                   nla_put_in_addr(skb, L2TP_ATTR_IP_DADDR,
-                                   inet->inet_daddr))
-                       goto nla_put_failure;
-               break;
-       }
+       if (l2tp_nl_tunnel_send_addr(skb, tunnel))
+               goto nla_put_failure;
 
-out:
        genlmsg_end(skb, hdr);
        return 0;