Add tou.c that implements common setsockopt functionality. This includes
initialization and argument structure for the setsockopt.

Signed-off-by: Tom Herbert <t...@herbertland.com>
---
 include/uapi/linux/if_tunnel.h |  10 ++++
 net/ipv4/Makefile              |   3 +-
 net/ipv4/af_inet.c             |   4 ++
 net/ipv4/tou.c                 | 132 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 148 insertions(+), 1 deletion(-)
 create mode 100644 net/ipv4/tou.c

diff --git a/include/uapi/linux/if_tunnel.h b/include/uapi/linux/if_tunnel.h
index af4de90..c6b4afa 100644
--- a/include/uapi/linux/if_tunnel.h
+++ b/include/uapi/linux/if_tunnel.h
@@ -71,6 +71,16 @@ enum tunnel_encap_types {
 #define TUNNEL_ENCAP_FLAG_CSUM6                (1<<1)
 #define TUNNEL_ENCAP_FLAG_REMCSUM      (1<<2)
 
+/* Structure for Transport Over UDP (TOU) encapsulation. This is used in
+ * setsockopt of inet sockets.
+ */
+struct tou_encap {
+       u16                     type; /* enum tunnel_encap_types */
+       u16                     flags;
+       __be16                  sport;
+       __be16                  dport;
+};
+
 /* SIT-mode i_flags */
 #define        SIT_ISATAP      0x0001
 
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index bfa1336..3b46dd6 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -12,7 +12,8 @@ obj-y     := route.o inetpeer.o protocol.o \
             tcp_offload.o datagram.o raw.o udp.o udplite.o \
             udp_offload.o arp.o icmp.o devinet.o af_inet.o igmp.o \
             fib_frontend.o fib_semantics.o fib_trie.o \
-            inet_fragment.o ping.o ip_tunnel_core.o gre_offload.o
+            inet_fragment.o ping.o ip_tunnel_core.o gre_offload.o \
+            tou.o
 
 obj-$(CONFIG_NET_IP_TUNNEL) += ip_tunnel.o
 obj-$(CONFIG_SYSCTL) += sysctl_net_ipv4.o
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 377424e..7a856f8 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -120,6 +120,7 @@
 #include <linux/mroute.h>
 #endif
 #include <net/l3mdev.h>
+#include <net/tou.h>
 
 
 /* The inetsw table contains everything that inet_create needs to
@@ -1822,6 +1823,9 @@ static int __init inet_init(void)
        /* Add UDP-Lite (RFC 3828) */
        udplite4_register();
 
+       /* Set TOU slab cache (Transport layer encapsulation over UDP) */
+       tou_init();
+
        ping_init();
 
        /*
diff --git a/net/ipv4/tou.c b/net/ipv4/tou.c
new file mode 100644
index 0000000..601466a
--- /dev/null
+++ b/net/ipv4/tou.c
@@ -0,0 +1,132 @@
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/socket.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <net/genetlink.h>
+#include <net/gue.h>
+#include <net/ip.h>
+#include <net/protocol.h>
+#include <net/udp.h>
+#include <net/udp_tunnel.h>
+#include <net/xfrm.h>
+#include <net/tou.h>
+#include <net/ip6_tunnel.h>
+#include <uapi/linux/fou.h>
+#include <uapi/linux/genetlink.h>
+
+static struct kmem_cache *tou_cachep __read_mostly;
+
+int tou_encap_setsockopt(struct sock *sk, char __user *optval, int optlen,
+                        bool is_ipv6)
+{
+       struct tou_encap te;
+       struct ip_tunnel_encap encap;
+       struct inet_sock *inet = inet_sk(sk);
+       struct ip_tunnel_encap *e = inet->tou_encap;
+       int hlen = 0, old_hlen = 0;
+
+       if (optlen < sizeof(te))
+               return -EINVAL;
+
+       if (copy_from_user(&te, optval, sizeof(te)))
+               return -EFAULT;
+
+       if (e) {
+               old_hlen = is_ipv6 ? ip6_encap_hlen(e) : ip_encap_hlen(e);
+               if (unlikely(old_hlen < 0))
+                       return -EINVAL;
+       }
+
+       if (te.type == TUNNEL_ENCAP_NONE) {
+               if (e) {
+                       if (unlikely(old_hlen < 0))
+                               return -EINVAL;
+
+                       inet->tou_encap = NULL;
+                       kmem_cache_free(tou_cachep, e);
+
+                       goto adjust_ext_hdr;
+               } else {
+                       return 0;
+               }
+       }
+
+       memset(&encap, 0, sizeof(encap));
+       encap.type = te.type;
+       encap.sport = te.sport;
+       encap.dport = te.dport;
+       encap.flags = te.flags;
+
+       hlen = is_ipv6 ? ip6_encap_hlen(e) : ip_encap_hlen(e);
+       if (hlen < 0)
+               return hlen;
+
+       if (!e) {
+               e = kmem_cache_alloc(tou_cachep, GFP_KERNEL);
+               if (!e)
+                       return -ENOMEM;
+               inet->tou_encap = e;
+       }
+
+       *e = encap;
+
+adjust_ext_hdr:
+       if (inet->is_icsk) {
+               struct inet_connection_sock *icsk = inet_csk(sk);
+
+               /* For a connected socket add the overhead of encapsulation
+                * (specifically the difference between the new encapsulation
+                * and the old one it present) into the extrenal header length
+                * and adjust the mss.
+                */
+               icsk->icsk_ext_hdr_len += (hlen - old_hlen);
+               icsk->icsk_sync_mss(sk, icsk->icsk_pmtu_cookie);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(tou_encap_setsockopt);
+
+int tou_encap_getsockopt(struct sock *sk, char __user *optval,
+                        int len, int __user *optlen, bool is_ipv6)
+{
+       struct tou_encap te;
+       struct inet_sock *inet = inet_sk(sk);
+       struct ip_tunnel_encap *e = inet->tou_encap;
+
+       if (len < sizeof(te))
+               return -EINVAL;
+
+       len = sizeof(te);
+
+       memset(&te, 0, sizeof(te));
+
+       if (!e) {
+               te.type = TUNNEL_ENCAP_NONE;
+       } else {
+               te.type = e->type;
+               te.sport = e->sport;
+               te.dport = e->dport;
+               te.flags = e->flags;
+       }
+
+       if (put_user(len, optlen))
+               return -EFAULT;
+
+       if (copy_to_user(optval, &te, len))
+               return -EFAULT;
+
+       return 0;
+}
+EXPORT_SYMBOL(tou_encap_getsockopt);
+
+void __init tou_init(void)
+{
+       tou_cachep = kmem_cache_create("tou_cache",
+                                      sizeof(struct ip_tunnel_encap), 0,
+                                      SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+}
-- 
2.8.0.rc2

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