path: root/net/ipv4/fou_core.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/udp.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <net/genetlink.h>
#include <net/gro.h>
#include <net/gue.h>
#include <net/fou.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/udp.h>
#include <net/udp_tunnel.h>
#include <uapi/linux/fou.h>
#include <uapi/linux/genetlink.h>

#include "fou_nl.h"

struct fou {
	struct socket *sock;
	u8 protocol;
	u8 flags;
	__be16 port;
	u8 family;
	u16 type;
	struct list_head list;
	struct rcu_head rcu;
};

#define FOU_F_REMCSUM_NOPARTIAL BIT(0)

struct fou_cfg {
	u16 type;
	u8 protocol;
	u8 flags;
	struct udp_port_cfg udp_config;
};

static unsigned int fou_net_id;

struct fou_net {
	struct list_head fou_list;
	struct mutex fou_lock;
};

static inline struct fou *fou_from_sock(struct sock *sk)
{
	return rcu_dereference_sk_user_data(sk);
}

static int fou_recv_pull(struct sk_buff *skb, struct fou *fou, size_t len)
{
	/* Remove 'len' bytes from the packet (UDP header and
	 * FOU header if present).
	 */
	if (fou->family == AF_INET)
		ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(skb)->tot_len) - len);
	else
		ipv6_hdr(skb)->payload_len =
		    htons(ntohs(ipv6_hdr(skb)->payload_len) - len);

	__skb_pull(skb, len);
	skb_postpull_rcsum(skb, udp_hdr(skb), len);
	skb_reset_transport_header(skb);
	return iptunnel_pull_offloads(skb);
}

static int fou_udp_recv(struct sock *sk, struct sk_buff *skb)
{
	struct fou *fou = fou_from_sock(sk);

	if (!fou)
		return 1;

	if (fou_recv_pull(skb, fou, sizeof(struct udphdr)))
		goto drop;

	return -fou->protocol;

drop:
	kfree_skb(skb);
	return 0;
}

static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
				  void *data, size_t hdrlen, u8 ipproto,
				  bool nopartial)
{
	__be16 *pd = data;
	size_t start = ntohs(pd[0]);
	size_t offset = ntohs(pd[1]);
	size_t plen = sizeof(struct udphdr) + hdrlen +
	    max_t(size_t, offset + sizeof(u16), start);

	if (skb->remcsum_offload)
		return guehdr;

	if (!pskb_may_pull(skb, plen))
		return NULL;
	guehdr = (struct guehdr *)&udp_hdr(skb)[1];

	skb_remcsum_process(skb, (void *)guehdr + hdrlen,
			    start, offset, nopartial);

	return guehdr;