tcp: add ipv6_addr_v4mapped_loopback() helper

tcp_twsk_unique() has a hard coded assumption about ipv4 loopback being 127/8 Lets instead use the standard ipv4_is_loopback() method, in a new ipv6_addr_v4mapped_loopback() helper. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
mariux64 · Oct 1, 2019 · be2644a · be2644a
1 parent 5be5515
commit be2644a
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Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
@@ -696,6 +696,11 @@ static inline bool ipv6_addr_v4mapped(const struct in6_addr *a)
 					cpu_to_be32(0x0000ffff))) == 0UL;
 }
 
+static inline bool ipv6_addr_v4mapped_loopback(const struct in6_addr *a)
+{
+	return ipv6_addr_v4mapped(a) && ipv4_is_loopback(a->s6_addr32[3]);
+}
+
 static inline u32 ipv6_portaddr_hash(const struct net *net,
 				     const struct in6_addr *addr6,
 				     unsigned int port)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
@@ -121,11 +121,9 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
 #if IS_ENABLED(CONFIG_IPV6)
 		if (tw->tw_family == AF_INET6) {
 			if (ipv6_addr_loopback(&tw->tw_v6_daddr) ||
-			    (ipv6_addr_v4mapped(&tw->tw_v6_daddr) &&
-			     (tw->tw_v6_daddr.s6_addr[12] == 127)) ||
+			    ipv6_addr_v4mapped_loopback(&tw->tw_v6_daddr) ||
 			    ipv6_addr_loopback(&tw->tw_v6_rcv_saddr) ||
-			    (ipv6_addr_v4mapped(&tw->tw_v6_rcv_saddr) &&
-			     (tw->tw_v6_rcv_saddr.s6_addr[12] == 127)))
+			    ipv6_addr_v4mapped_loopback(&tw->tw_v6_rcv_saddr))
 				loopback = true;
 		} else
 #endif