linux/net/ipv4/ip_options.c

// SPDX-License-Identifier: GPL-2.0
/*
 * 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.
 *
 *		The options processing module for ip.c
 *
 * Authors:	A.N.Kuznetsov
 *
 */

#define pr_fmt(fmt) …

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/cipso_ipv4.h>
#include <net/ip_fib.h>

/*
 * Write options to IP header, record destination address to
 * source route option, address of outgoing interface
 * (we should already know it, so that this  function is allowed be
 * called only after routing decision) and timestamp,
 * if we originate this datagram.
 *
 * daddr is real destination address, next hop is recorded in IP header.
 * saddr is address of outgoing interface.
 */

void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
		      __be32 daddr, struct rtable *rt)
{ … }

/*
 * Provided (sopt, skb) points to received options,
 * build in dopt compiled option set appropriate for answering.
 * i.e. invert SRR option, copy anothers,
 * and grab room in RR/TS options.
 *
 * NOTE: dopt cannot point to skb.
 */

int __ip_options_echo(struct net *net, struct ip_options *dopt,
		      struct sk_buff *skb, const struct ip_options *sopt)
{ … }

/*
 *	Options "fragmenting", just fill options not
 *	allowed in fragments with NOOPs.
 *	Simple and stupid 8), but the most efficient way.
 */

void ip_options_fragment(struct sk_buff *skb)
{ … }

/* helper used by ip_options_compile() to call fib_compute_spec_dst()
 * at most one time.
 */
static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
{ … }

/*
 * Verify options and fill pointers in struct options.
 * Caller should clear *opt, and set opt->data.
 * If opt == NULL, then skb->data should point to IP header.
 */

int __ip_options_compile(struct net *net,
			 struct ip_options *opt, struct sk_buff *skb,
			 __be32 *info)
{ … }
EXPORT_SYMBOL(…);

int ip_options_compile(struct net *net,
		       struct ip_options *opt, struct sk_buff *skb)
{ … }
EXPORT_SYMBOL(…);

/*
 *	Undo all the changes done by ip_options_compile().
 */

void ip_options_undo(struct ip_options *opt)
{ … }

int ip_options_get(struct net *net, struct ip_options_rcu **optp,
		   sockptr_t data, int optlen)
{ … }

void ip_forward_options(struct sk_buff *skb)
{ … }

int ip_options_rcv_srr(struct sk_buff *skb, struct net_device *dev)
{ … }
EXPORT_SYMBOL(…);