net: inet_diag: export IPV6_V6ONLY sockopt

For AF_INET6 sockets, the value of struct ipv6_pinfo.ipv6only is
exported to userspace. It indicates whether a socket bound to in6addr_any
listens on IPv4 as well as IPv6. Since the socket is natively IPv6, it is not
listed by e.g. 'ss -l -4'.

This patch is accompanied by an appropriate one for iproute2 to enable
the additional information in 'ss -e'.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 1 deletions

diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index b629fc53b109..68a1f71fde9f 100644
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -112,9 +112,10 @@ enum {
         INET_DIAG_SHUTDOWN,
         INET_DIAG_DCTCPINFO,
         INET_DIAG_PROTOCOL,  /* response attribute only */
+        INET_DIAG_SKV6ONLY,
 };
 
-#define INET_DIAG_MAX INET_DIAG_PROTOCOL
+#define INET_DIAG_MAX INET_DIAG_SKV6ONLY
 
 /* INET_DIAG_MEM */
 
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 516a1f6fbdd3..9bc26677058e 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -151,6 +151,10 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
                         if (nla_put_u8(skb, INET_DIAG_TCLASS,
                                        inet6_sk(sk)->tclass) < 0)
                                 goto errout;
+
+                if (ipv6_only_sock(sk) &&
+                    nla_put_u8(skb, INET_DIAG_SKV6ONLY, 1))
+                        goto errout;
         }
 #endif