net: Convert protocol error handlers from void to int

We'll need this to handle ICMP errors for tunnels without a sending socket
(i.e. FoU and GUE). There, we might have to look up different types of IP
tunnels, registered as network protocols, before we get a match, so we
want this for the error handlers of IPPROTO_IPIP and IPPROTO_IPV6 in both
inet_protos and inet6_protos. These error codes will be used in the next
patch.

For consistency, return sensible error codes in protocol error handlers
whenever handlers can't handle errors because, even if valid, they don't
match a protocol or any of its states.

This has no effect on existing error handling paths.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 10 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index de47038afdf0..a336787d75e5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -423,7 +423,7 @@ EXPORT_SYMBOL(tcp_req_err);
  *
  */
 
-void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+int tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 {
         const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
         struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
@@ -446,20 +446,21 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
                                        inet_iif(icmp_skb), 0);
         if (!sk) {
                 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
-                return;
+                return -ENOENT;
         }
         if (sk->sk_state == TCP_TIME_WAIT) {
                 inet_twsk_put(inet_twsk(sk));
-                return;
+                return 0;
         }
         seq = ntohl(th->seq);
-        if (sk->sk_state == TCP_NEW_SYN_RECV)
-                return tcp_req_err(sk, seq,
-                                  type == ICMP_PARAMETERPROB ||
-                                  type == ICMP_TIME_EXCEEDED ||
-                                  (type == ICMP_DEST_UNREACH &&
-                                   (code == ICMP_NET_UNREACH ||
-                                    code == ICMP_HOST_UNREACH)));
+        if (sk->sk_state == TCP_NEW_SYN_RECV) {
+                tcp_req_err(sk, seq, type == ICMP_PARAMETERPROB ||
+                                     type == ICMP_TIME_EXCEEDED ||
+                                     (type == ICMP_DEST_UNREACH &&
+                                      (code == ICMP_NET_UNREACH ||
+                                       code == ICMP_HOST_UNREACH)));
+                return 0;
+        }
 
         bh_lock_sock(sk);
         /* If too many ICMPs get dropped on busy
@@ -613,6 +614,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 out:
         bh_unlock_sock(sk);
         sock_put(sk);
+        return 0;
 }
 
 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)