Add a helper to directly set the IPV6_V6ONLY sockopt from kernel space
without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 include/net/ipv6.h        |  3 +++
 net/ipv6/ip6_udp_tunnel.c |  5 +----
 net/ipv6/ipv6_sockglue.c  | 11 +++++++++++
 net/sunrpc/svcsock.c      |  8 ++------
 4 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 955badd1e8ffc..e24b59201a00d 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1174,4 +1174,7 @@ int ipv6_sock_mc_join_ssm(struct sock *sk, int ifindex,
                          const struct in6_addr *addr, unsigned int mode);
 int ipv6_sock_mc_drop(struct sock *sk, int ifindex,
                      const struct in6_addr *addr);
+
+int ip6_sock_set_v6only(struct sock *sk, bool val);
+
 #endif /* _NET_IPV6_H */
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
index 6523609516d25..bc4ee5cb14c8b 100644
--- a/net/ipv6/ip6_udp_tunnel.c
+++ b/net/ipv6/ip6_udp_tunnel.c
@@ -25,10 +25,7 @@ int udp_sock_create6(struct net *net, struct udp_port_cfg 
*cfg,
                goto error;
 
        if (cfg->ipv6_v6only) {
-               int val = 1;
-
-               err = kernel_setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY,
-                                       (char *) &val, sizeof(val));
+               err = ip6_sock_set_v6only(sock->sk, true);
                if (err < 0)
                        goto error;
        }
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 18d05403d3b52..f26224bb3e098 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -136,6 +136,17 @@ static bool setsockopt_needs_rtnl(int optname)
        return false;
 }
 
+int ip6_sock_set_v6only(struct sock *sk, bool val)
+{
+       if (inet_sk(sk)->inet_num)
+               return -EINVAL;
+       lock_sock(sk);
+       sk->sk_ipv6only = val;
+       release_sock(sk);
+       return 0;
+}
+EXPORT_SYMBOL(ip6_sock_set_v6only);
+
 static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
                    char __user *optval, unsigned int optlen)
 {
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 7a4f01c79e0f1..7fa7fedec3c5a 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1328,7 +1328,6 @@ static struct svc_xprt *svc_create_socket(struct svc_serv 
*serv,
        struct sockaddr *newsin = (struct sockaddr *)&addr;
        int             newlen;
        int             family;
-       int             val;
        RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
 
        dprintk("svc: svc_create_socket(%s, %d, %s)\n",
@@ -1364,11 +1363,8 @@ static struct svc_xprt *svc_create_socket(struct 
svc_serv *serv,
         * getting requests from IPv4 remotes.  Those should
         * be shunted to a PF_INET listener via rpcbind.
         */
-       val = 1;
-       if (family == PF_INET6)
-               kernel_setsockopt(sock, SOL_IPV6, IPV6_V6ONLY,
-                                       (char *)&val, sizeof(val));
-
+       if (family == PF_INET6 && IS_REACHABLE(CONFIG_IPV6))
+               ip6_sock_set_v6only(sock->sk, true);
        if (type == SOCK_STREAM)
                sock->sk->sk_reuse = SK_CAN_REUSE; /* allow address reuse */
        error = kernel_bind(sock, sin, len);
-- 
2.26.2

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