udp: Add udp_sock_create for UDP tunnels to open listener socket

Added udp_tunnel.c which can contain some common functions for UDP
tunnels. The first function in this is udp_sock_create which is used
to open the listener port for a UDP tunnel.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 105 insertions, 0 deletions

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 05c57f0fcabe..dbc10d84161f 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -307,6 +307,10 @@ config NET_IPVTI
           the notion of a secure tunnel for IPSEC and then use routing protocol
           on top.
 
+config NET_UDP_TUNNEL
+        tristate
+        default n
+
 config INET_AH
         tristate "IP: AH transformation"
         select XFRM_ALGO
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index f032688d20d3..8ee1cd4053ee 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_NET_IPIP) += ipip.o
 gre-y := gre_demux.o
 obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
 obj-$(CONFIG_NET_IPGRE) += ip_gre.o
+obj-$(CONFIG_NET_UDP_TUNNEL) += udp_tunnel.o
 obj-$(CONFIG_NET_IPVTI) += ip_vti.o
 obj-$(CONFIG_SYN_COOKIES) += syncookies.o
 obj-$(CONFIG_INET_AH) += ah4.o
diff --git a/net/ipv4/udp_tunnel.c b/net/ipv4/udp_tunnel.c
new file mode 100644
index 000000000000..61ec1a65207e
--- /dev/null
+++ b/net/ipv4/udp_tunnel.c
@@ -0,0 +1,100 @@
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/socket.h>
+#include <linux/udp.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <net/udp.h>
+#include <net/udp_tunnel.h>
+#include <net/net_namespace.h>
+
+int udp_sock_create(struct net *net, struct udp_port_cfg *cfg,
+                    struct socket **sockp)
+{
+        int err = -EINVAL;
+        struct socket *sock = NULL;
+
+#if IS_ENABLED(CONFIG_IPV6)
+        if (cfg->family == AF_INET6) {
+                struct sockaddr_in6 udp6_addr;
+
+                err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
+                if (err < 0)
+                        goto error;
+
+                sk_change_net(sock->sk, net);
+
+                udp6_addr.sin6_family = AF_INET6;
+                memcpy(&udp6_addr.sin6_addr, &cfg->local_ip6,
+                       sizeof(udp6_addr.sin6_addr));
+                udp6_addr.sin6_port = cfg->local_udp_port;
+                err = kernel_bind(sock, (struct sockaddr *)&udp6_addr,
+                                  sizeof(udp6_addr));
+                if (err < 0)
+                        goto error;
+
+                if (cfg->peer_udp_port) {
+                        udp6_addr.sin6_family = AF_INET6;
+                        memcpy(&udp6_addr.sin6_addr, &cfg->peer_ip6,
+                               sizeof(udp6_addr.sin6_addr));
+                        udp6_addr.sin6_port = cfg->peer_udp_port;
+                        err = kernel_connect(sock,
+                                             (struct sockaddr *)&udp6_addr,
+                                             sizeof(udp6_addr), 0);
+                }
+                if (err < 0)
+                        goto error;
+
+                udp_set_no_check6_tx(sock->sk, !cfg->use_udp6_tx_checksums);
+                udp_set_no_check6_rx(sock->sk, !cfg->use_udp6_rx_checksums);
+        } else
+#endif
+        if (cfg->family == AF_INET) {
+                struct sockaddr_in udp_addr;
+
+                err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
+                if (err < 0)
+                        goto error;
+
+                sk_change_net(sock->sk, net);
+
+                udp_addr.sin_family = AF_INET;
+                udp_addr.sin_addr = cfg->local_ip;
+                udp_addr.sin_port = cfg->local_udp_port;
+                err = kernel_bind(sock, (struct sockaddr *)&udp_addr,
+                                  sizeof(udp_addr));
+                if (err < 0)
+                        goto error;
+
+                if (cfg->peer_udp_port) {
+                        udp_addr.sin_family = AF_INET;
+                        udp_addr.sin_addr = cfg->peer_ip;
+                        udp_addr.sin_port = cfg->peer_udp_port;
+                        err = kernel_connect(sock,
+                                             (struct sockaddr *)&udp_addr,
+                                             sizeof(udp_addr), 0);
+                        if (err < 0)
+                                goto error;
+                }
+
+                sock->sk->sk_no_check_tx = !cfg->use_udp_checksums;
+        } else {
+                return -EPFNOSUPPORT;
+        }
+
+
+        *sockp = sock;
+
+        return 0;
+
+error:
+        if (sock) {
+                kernel_sock_shutdown(sock, SHUT_RDWR);
+                sk_release_kernel(sock->sk);
+        }
+        *sockp = NULL;
+        return err;
+}
+EXPORT_SYMBOL(udp_sock_create);
+
+MODULE_LICENSE("GPL");