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-rw-r--r--include/uapi/linux/fou.h32
-rw-r--r--net/ipv4/Kconfig10
-rw-r--r--net/ipv4/Makefile1
-rw-r--r--net/ipv4/fou.c279
4 files changed, 322 insertions, 0 deletions
diff --git a/include/uapi/linux/fou.h b/include/uapi/linux/fou.h
new file mode 100644
index 000000000000..e03376de453d
--- /dev/null
+++ b/include/uapi/linux/fou.h
@@ -0,0 +1,32 @@
+/* fou.h - FOU Interface */
+
+#ifndef _UAPI_LINUX_FOU_H
+#define _UAPI_LINUX_FOU_H
+
+/* NETLINK_GENERIC related info
+ */
+#define FOU_GENL_NAME "fou"
+#define FOU_GENL_VERSION 0x1
+
+enum {
+ FOU_ATTR_UNSPEC,
+ FOU_ATTR_PORT, /* u16 */
+ FOU_ATTR_AF, /* u8 */
+ FOU_ATTR_IPPROTO, /* u8 */
+
+ __FOU_ATTR_MAX,
+};
+
+#define FOU_ATTR_MAX (__FOU_ATTR_MAX - 1)
+
+enum {
+ FOU_CMD_UNSPEC,
+ FOU_CMD_ADD,
+ FOU_CMD_DEL,
+
+ __FOU_CMD_MAX,
+};
+
+#define FOU_CMD_MAX (__FOU_CMD_MAX - 1)
+
+#endif /* _UAPI_LINUX_FOU_H */
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index dbc10d84161f..84f710b7472a 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -311,6 +311,16 @@ config NET_UDP_TUNNEL
tristate
default n
+config NET_FOU
+ tristate "IP: Foo (IP protocols) over UDP"
+ select XFRM
+ select NET_UDP_TUNNEL
+ ---help---
+ Foo over UDP allows any IP protocol to be directly encapsulated
+ over UDP include tunnels (IPIP, GRE, SIT). By encapsulating in UDP
+ network mechanisms and optimizations for UDP (such as ECMP
+ and RSS) can be leveraged to provide better service.
+
config INET_AH
tristate "IP: AH transformation"
select XFRM_ALGO
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 8ee1cd4053ee..d78d404c596f 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_IP_MULTIPLE_TABLES) += fib_rules.o
obj-$(CONFIG_IP_MROUTE) += ipmr.o
obj-$(CONFIG_NET_IPIP) += ipip.o
gre-y := gre_demux.o
+obj-$(CONFIG_NET_FOU) += fou.o
obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
obj-$(CONFIG_NET_IPGRE) += ip_gre.o
obj-$(CONFIG_NET_UDP_TUNNEL) += udp_tunnel.o
diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
new file mode 100644
index 000000000000..d44f97b79418
--- /dev/null
+++ b/net/ipv4/fou.c
@@ -0,0 +1,279 @@
+#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/ip.h>
+#include <net/udp.h>
+#include <net/udp_tunnel.h>
+#include <net/xfrm.h>
+#include <uapi/linux/fou.h>
+#include <uapi/linux/genetlink.h>
+
+static DEFINE_SPINLOCK(fou_lock);
+static LIST_HEAD(fou_list);
+
+struct fou {
+ struct socket *sock;
+ u8 protocol;
+ u16 port;
+ struct list_head list;
+};
+
+struct fou_cfg {
+ u8 protocol;
+ struct udp_port_cfg udp_config;
+};
+
+static inline struct fou *fou_from_sock(struct sock *sk)
+{
+ return sk->sk_user_data;
+}
+
+static int fou_udp_encap_recv_deliver(struct sk_buff *skb,
+ u8 protocol, size_t len)
+{
+ struct iphdr *iph = ip_hdr(skb);
+
+ /* Remove 'len' bytes from the packet (UDP header and
+ * FOU header if present), modify the protocol to the one
+ * we found, and then call rcv_encap.
+ */
+ iph->tot_len = htons(ntohs(iph->tot_len) - len);
+ __skb_pull(skb, len);
+ skb_postpull_rcsum(skb, udp_hdr(skb), len);
+ skb_reset_transport_header(skb);
+
+ return -protocol;
+}
+
+static int fou_udp_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct fou *fou = fou_from_sock(sk);
+
+ if (!fou)
+ return 1;
+
+ return fou_udp_encap_recv_deliver(skb, fou->protocol,
+ sizeof(struct udphdr));
+}
+
+static int fou_add_to_port_list(struct fou *fou)
+{
+ struct fou *fout;
+
+ spin_lock(&fou_lock);
+ list_for_each_entry(fout, &fou_list, list) {
+ if (fou->port == fout->port) {
+ spin_unlock(&fou_lock);
+ return -EALREADY;
+ }
+ }
+
+ list_add(&fou->list, &fou_list);
+ spin_unlock(&fou_lock);
+
+ return 0;
+}
+
+static void fou_release(struct fou *fou)
+{
+ struct socket *sock = fou->sock;
+ struct sock *sk = sock->sk;
+
+ udp_del_offload(&fou->udp_offloads);
+
+ list_del(&fou->list);
+
+ /* Remove hooks into tunnel socket */
+ sk->sk_user_data = NULL;
+
+ sock_release(sock);
+
+ kfree(fou);
+}
+
+static int fou_create(struct net *net, struct fou_cfg *cfg,
+ struct socket **sockp)
+{
+ struct fou *fou = NULL;
+ int err;
+ struct socket *sock = NULL;
+ struct sock *sk;
+
+ /* Open UDP socket */
+ err = udp_sock_create(net, &cfg->udp_config, &sock);
+ if (err < 0)
+ goto error;
+
+ /* Allocate FOU port structure */
+ fou = kzalloc(sizeof(*fou), GFP_KERNEL);
+ if (!fou) {
+ err = -ENOMEM;
+ goto error;
+ }
+
+ sk = sock->sk;
+
+ /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
+ fou->protocol = cfg->protocol;
+ fou->port = cfg->udp_config.local_udp_port;
+ udp_sk(sk)->encap_rcv = fou_udp_recv;
+
+ udp_sk(sk)->encap_type = 1;
+ udp_encap_enable();
+
+ sk->sk_user_data = fou;
+ fou->sock = sock;
+
+ udp_set_convert_csum(sk, true);
+
+ sk->sk_allocation = GFP_ATOMIC;
+
+ err = fou_add_to_port_list(fou);
+ if (err)
+ goto error;
+
+ if (sockp)
+ *sockp = sock;
+
+ return 0;
+
+error:
+ kfree(fou);
+ if (sock)
+ sock_release(sock);
+
+ return err;
+}
+
+static int fou_destroy(struct net *net, struct fou_cfg *cfg)
+{
+ struct fou *fou;
+ u16 port = cfg->udp_config.local_udp_port;
+ int err = -EINVAL;
+
+ spin_lock(&fou_lock);
+ list_for_each_entry(fou, &fou_list, list) {
+ if (fou->port == port) {
+ fou_release(fou);
+ err = 0;
+ break;
+ }
+ }
+ spin_unlock(&fou_lock);
+
+ return err;
+}
+
+static struct genl_family fou_nl_family = {
+ .id = GENL_ID_GENERATE,
+ .hdrsize = 0,
+ .name = FOU_GENL_NAME,
+ .version = FOU_GENL_VERSION,
+ .maxattr = FOU_ATTR_MAX,
+ .netnsok = true,
+};
+
+static struct nla_policy fou_nl_policy[FOU_ATTR_MAX + 1] = {
+ [FOU_ATTR_PORT] = { .type = NLA_U16, },
+ [FOU_ATTR_AF] = { .type = NLA_U8, },
+ [FOU_ATTR_IPPROTO] = { .type = NLA_U8, },
+};
+
+static int parse_nl_config(struct genl_info *info,
+ struct fou_cfg *cfg)
+{
+ memset(cfg, 0, sizeof(*cfg));
+
+ cfg->udp_config.family = AF_INET;
+
+ if (info->attrs[FOU_ATTR_AF]) {
+ u8 family = nla_get_u8(info->attrs[FOU_ATTR_AF]);
+
+ if (family != AF_INET && family != AF_INET6)
+ return -EINVAL;
+
+ cfg->udp_config.family = family;
+ }
+
+ if (info->attrs[FOU_ATTR_PORT]) {
+ u16 port = nla_get_u16(info->attrs[FOU_ATTR_PORT]);
+
+ cfg->udp_config.local_udp_port = port;
+ }
+
+ if (info->attrs[FOU_ATTR_IPPROTO])
+ cfg->protocol = nla_get_u8(info->attrs[FOU_ATTR_IPPROTO]);
+
+ return 0;
+}
+
+static int fou_nl_cmd_add_port(struct sk_buff *skb, struct genl_info *info)
+{
+ struct fou_cfg cfg;
+ int err;
+
+ err = parse_nl_config(info, &cfg);
+ if (err)
+ return err;
+
+ return fou_create(&init_net, &cfg, NULL);
+}
+
+static int fou_nl_cmd_rm_port(struct sk_buff *skb, struct genl_info *info)
+{
+ struct fou_cfg cfg;
+
+ parse_nl_config(info, &cfg);
+
+ return fou_destroy(&init_net, &cfg);
+}
+
+static const struct genl_ops fou_nl_ops[] = {
+ {
+ .cmd = FOU_CMD_ADD,
+ .doit = fou_nl_cmd_add_port,
+ .policy = fou_nl_policy,
+ .flags = GENL_ADMIN_PERM,
+ },
+ {
+ .cmd = FOU_CMD_DEL,
+ .doit = fou_nl_cmd_rm_port,
+ .policy = fou_nl_policy,
+ .flags = GENL_ADMIN_PERM,
+ },
+};
+
+static int __init fou_init(void)
+{
+ int ret;
+
+ ret = genl_register_family_with_ops(&fou_nl_family,
+ fou_nl_ops);
+
+ return ret;
+}
+
+static void __exit fou_fini(void)
+{
+ struct fou *fou, *next;
+
+ genl_unregister_family(&fou_nl_family);
+
+ /* Close all the FOU sockets */
+
+ spin_lock(&fou_lock);
+ list_for_each_entry_safe(fou, next, &fou_list, list)
+ fou_release(fou);
+ spin_unlock(&fou_lock);
+}
+
+module_init(fou_init);
+module_exit(fou_fini);
+MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
+MODULE_LICENSE("GPL");
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.