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

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 include/net/sock.h        |  1 +
 net/core/sock.c           | 21 +++++++++++++++------
 net/ipv4/udp_tunnel.c     |  4 +---
 net/ipv6/ip6_udp_tunnel.c |  4 +---
 4 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 809596ffd32d2..b63ea15362065 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2691,5 +2691,6 @@ void sock_set_reuseaddr(struct sock *sk, unsigned char 
reuse);
 void sock_set_linger(struct sock *sk, bool onoff, unsigned int linger);
 void sock_set_priority(struct sock *sk, u32 priority);
 void sock_set_sndtimeo(struct sock *sk, unsigned int secs);
+int sock_bindtoindex(struct sock *sk, int ifindex);
 
 #endif /* _SOCK_H */
diff --git a/net/core/sock.c b/net/core/sock.c
index 76527681e50b9..4b7439308caec 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -566,7 +566,7 @@ struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie)
 }
 EXPORT_SYMBOL(sk_dst_check);
 
-static int sock_setbindtodevice_locked(struct sock *sk, int ifindex)
+static int sock_bindtoindex_locked(struct sock *sk, int ifindex)
 {
        int ret = -ENOPROTOOPT;
 #ifdef CONFIG_NETDEVICES
@@ -594,6 +594,18 @@ static int sock_setbindtodevice_locked(struct sock *sk, 
int ifindex)
        return ret;
 }
 
+int sock_bindtoindex(struct sock *sk, int ifindex)
+{
+       int ret;
+
+       lock_sock(sk);
+       ret = sock_bindtoindex_locked(sk, ifindex);
+       release_sock(sk);
+
+       return ret;
+}
+EXPORT_SYMBOL(sock_bindtoindex);
+
 static int sock_setbindtodevice(struct sock *sk, char __user *optval,
                                int optlen)
 {
@@ -634,10 +646,7 @@ static int sock_setbindtodevice(struct sock *sk, char 
__user *optval,
                        goto out;
        }
 
-       lock_sock(sk);
-       ret = sock_setbindtodevice_locked(sk, index);
-       release_sock(sk);
-
+       return sock_bindtoindex(sk, index);
 out:
 #endif
 
@@ -1221,7 +1230,7 @@ int sock_setsockopt(struct socket *sock, int level, int 
optname,
                break;
 
        case SO_BINDTOIFINDEX:
-               ret = sock_setbindtodevice_locked(sk, val);
+               ret = sock_bindtoindex_locked(sk, val);
                break;
 
        default:
diff --git a/net/ipv4/udp_tunnel.c b/net/ipv4/udp_tunnel.c
index 150e6f0fdbf59..2158e8bddf41c 100644
--- a/net/ipv4/udp_tunnel.c
+++ b/net/ipv4/udp_tunnel.c
@@ -22,9 +22,7 @@ int udp_sock_create4(struct net *net, struct udp_port_cfg 
*cfg,
                goto error;
 
        if (cfg->bind_ifindex) {
-               err = kernel_setsockopt(sock, SOL_SOCKET, SO_BINDTOIFINDEX,
-                                       (void *)&cfg->bind_ifindex,
-                                       sizeof(cfg->bind_ifindex));
+               err = sock_bindtoindex(sock->sk, cfg->bind_ifindex);
                if (err < 0)
                        goto error;
        }
diff --git a/net/ipv6/ip6_udp_tunnel.c b/net/ipv6/ip6_udp_tunnel.c
index 58956a6b66a21..6523609516d25 100644
--- a/net/ipv6/ip6_udp_tunnel.c
+++ b/net/ipv6/ip6_udp_tunnel.c
@@ -33,9 +33,7 @@ int udp_sock_create6(struct net *net, struct udp_port_cfg 
*cfg,
                        goto error;
        }
        if (cfg->bind_ifindex) {
-               err = kernel_setsockopt(sock, SOL_SOCKET, SO_BINDTOIFINDEX,
-                                       (void *)&cfg->bind_ifindex,
-                                       sizeof(cfg->bind_ifindex));
+               err = sock_bindtoindex(sock->sk, cfg->bind_ifindex);
                if (err < 0)
                        goto error;
        }
-- 
2.26.2

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