path: root/include/net/ip.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the IP module.
 *
 * Version:	@(#)ip.h	1.0.2	05/07/93
 *
 * Authors:	Ross Biro
 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Alan Cox, <gw4pts@gw4pts.ampr.org>
 *
 * Changes:
 *		Mike McLagan    :       Routing by source
 */
#ifndef _IP_H
#define _IP_H

#include <linux/types.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/skbuff.h>
#include <linux/jhash.h>

#include <net/inet_sock.h>
#include <net/route.h>
#include <net/snmp.h>
#include <net/flow.h>
#include <net/flow_dissector.h>
#include <net/netns/hash.h>

#define IPV4_MAX_PMTU		65535U		/* RFC 2675, Section 5.1 */
#define IPV4_MIN_MTU		68			/* RFC 791 */

extern unsigned int sysctl_fib_sync_mem;
extern unsigned int sysctl_fib_sync_mem_min;
extern unsigned int sysctl_fib_sync_mem_max;

struct sock;

struct inet_skb_parm {
	int			iif;
	struct ip_options	opt;		/* Compiled IP options		*/
	u16			flags;

#define IPSKB_FORWARDED		BIT(0)
#define IPSKB_XFRM_TUNNEL_SIZE	BIT(1)
#define IPSKB_XFRM_TRANSFORMED	BIT(2)
#define IPSKB_FRAG_COMPLETE	BIT(3)
#define IPSKB_REROUTED		BIT(4)
#define IPSKB_DOREDIRECT	BIT(5)
#define IPSKB_FRAG_PMTU		BIT(6)
#define IPSKB_L3SLAVE		BIT(7)

	u16			frag_max_size;
};

static inline bool ipv4_l3mdev_skb(u16 flags)
{
	return !!(flags & IPSKB_L3SLAVE);
}

static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
{
	return ip_hdr(skb)->ihl * 4;
}

struct ipcm_cookie {
	struct sockcm_cookie	sockc;
	__be32			addr;
	int			oif;
	struct ip_options_rcu	*opt;
	__u8			ttl;
	__s16			tos;
	char			priority;
	__u16			gso_size;
};

static inline void ipcm_init(struct ipcm_cookie *ipcm)
{
	*ipcm = (struct ipcm_cookie) { .tos = -1 };
}

static inline void ipcm_init_sk(struct ipcm_cookie *ipcm,
				const struct inet_sock *inet)
{
	ipcm_init(ipcm);

	ipcm->sockc.mark = inet->sk.sk_mark;
	ipcm->sockc.tsflags = inet->sk.sk_tsflags;
	ipcm->oif = inet->sk.sk_bound_dev_if;
	ipcm->addr = inet->inet_saddr;
}

#define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
#define PKTINFO_SKB_CB(skb) ((struct in_pktinfo *)((skb)->cb))

/* return enslaved device index if relevant */
static inline int inet_sdif(struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
	if (skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
		return IPCB(skb)->iif;
#endif
	return 0;
}

/* Special input handler for packets caught by router alert option.
   They are selected only by protocol field, and then processed likely
   local ones; but only if someone wants them! Otherwise, router
   not running rsvpd will kill RSVP.

   It is user level problem, what it will make with them.
   I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
   but receiver should be enough clever f.e. to forward mtrace requests,
   sent to multicast group to reach destination designated router.
 */

struct ip_ra_chain {
	struct ip_ra_chain __rcu *next;
	struct sock		*sk;
	union {
		void			(*destructor)(struct sock *);
		struct sock		*saved_sk;
	};
	struct rcu_head		rcu;
};

/* IP flags. */
#define IP_CE		0x8000		/* Flag: "Congestion"		*/
#define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
#define IP_MF		0x2000		/* Flag: "More Fragments"	*/
#define IP_OFFSET	0x1FFF		/* "Fragment Offset" part	*/

#define IP_FRAG_TIME	(30 * HZ)		/* fragment lifetime	*/

struct msghdr;
struct net_device;
struct packet_type;
struct rtable;
struct sockaddr;

int igmp_mc_init(void);

/*
 *	Functions provided by ip.c
 */

int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
			  __be32 saddr, __be32 daddr,
			  struct ip_options_rcu *opt);
int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
	   struct net_device *orig_dev);
void ip_list_rcv(struct list_head *head, struct packet_type *pt,
		 struct net_device *orig_dev);
int ip_local_deliver(struct sk_buff *skb);
void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int proto);
int ip_mr_input(struct sk_buff *skb);
int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb);
int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb);
int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
		   int (*output)(struct net *, struct sock *, struct sk_buff *));

struct ip_fraglist_iter {
	struct sk_buff	*frag;
	struct iphdr	*iph;
	int		offset;
	unsigned int	hlen;
};

void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
		      unsigned int hlen, struct ip_fraglist_iter *iter);
void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter);

static inline struct sk_buff *ip_fraglist_next(struct ip_fraglist_iter *iter)
{
	struct sk_buff *skb = iter->frag;

	iter->frag = skb->next;
	skb_mark_not_on_list(skb);

	return skb;
}

struct ip_frag_state {
	bool		DF;
	unsigned int	hlen;
	unsigned int	ll_rs;
	unsigned int	mtu;
	unsigned int	left;
	int		offset;
	int		ptr;
	__be16		not_last_frag;
};

void ip_frag_init(struct sk_buff *skb, unsigned int hlen, unsigned int ll_rs,
		  unsigned int mtu, bool DF, struct ip_frag_state *state);
struct sk_buff *ip_frag_next(struct sk_buff *skb,
			     struct ip_frag_state *state);

void ip_send_check(struct iphdr *ip);
int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb);
int ip_local_out(struct net *net, struct sock