path: root/net/ipv4/arp.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* linux/net/ipv4/arp.c
 *
 * Copyright (C) 1994 by Florian  La Roche
 *
 * This module implements the Address Resolution Protocol ARP (RFC 826),
 * which is used to convert IP addresses (or in the future maybe other
 * high-level addresses) into a low-level hardware address (like an Ethernet
 * address).
 *
 * Fixes:
 *		Alan Cox	:	Removed the Ethernet assumptions in
 *					Florian's code
 *		Alan Cox	:	Fixed some small errors in the ARP
 *					logic
 *		Alan Cox	:	Allow >4K in /proc
 *		Alan Cox	:	Make ARP add its own protocol entry
 *		Ross Martin     :       Rewrote arp_rcv() and arp_get_info()
 *		Stephen Henson	:	Add AX25 support to arp_get_info()
 *		Alan Cox	:	Drop data when a device is downed.
 *		Alan Cox	:	Use init_timer().
 *		Alan Cox	:	Double lock fixes.
 *		Martin Seine	:	Move the arphdr structure
 *					to if_arp.h for compatibility.
 *					with BSD based programs.
 *		Andrew Tridgell :       Added ARP netmask code and
 *					re-arranged proxy handling.
 *		Alan Cox	:	Changed to use notifiers.
 *		Niibe Yutaka	:	Reply for this device or proxies only.
 *		Alan Cox	:	Don't proxy across hardware types!
 *		Jonathan Naylor :	Added support for NET/ROM.
 *		Mike Shaver     :       RFC1122 checks.
 *		Jonathan Naylor :	Only lookup the hardware address for
 *					the correct hardware type.
 *		Germano Caronni	:	Assorted subtle races.
 *		Craig Schlenter :	Don't modify permanent entry
 *					during arp_rcv.
 *		Russ Nelson	:	Tidied up a few bits.
 *		Alexey Kuznetsov:	Major changes to caching and behaviour,
 *					eg intelligent arp probing and
 *					generation
 *					of host down events.
 *		Alan Cox	:	Missing unlock in device events.
 *		Eckes		:	ARP ioctl control errors.
 *		Alexey Kuznetsov:	Arp free fix.
 *		Manuel Rodriguez:	Gratuitous ARP.
 *              Jonathan Layes  :       Added arpd support through kerneld
 *                                      message queue (960314)
 *		Mike Shaver	:	/proc/sys/net/ipv4/arp_* support
 *		Mike McLagan    :	Routing by source
 *		Stuart Cheshire	:	Metricom and grat arp fixes
 *					*** FOR 2.1 clean this up ***
 *		Lawrence V. Stefani: (08/12/96) Added FDDI support.
 *		Alan Cox	:	Took the AP1000 nasty FDDI hack and
 *					folded into the mainstream FDDI code.
 *					Ack spit, Linus how did you allow that
 *					one in...
 *		Jes Sorensen	:	Make FDDI work again in 2.1.x and
 *					clean up the APFDDI & gen. FDDI bits.
 *		Alexey Kuznetsov:	new arp state machine;
 *					now it is in net/core/neighbour.c.
 *		Krzysztof Halasa:	Added Frame Relay ARP support.
 *		Arnaldo C. Melo :	convert /proc/net/arp to seq_file
 *		Shmulik Hen:		Split arp_send to arp_create and
 *					arp_xmit so intermediate drivers like
 *					bonding can change the skb before
 *					sending (e.g. insert 8021q tag).
 *		Harald Welte	:	convert to make use of jenkins hash
 *		Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/capability.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/mm.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/fddidevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/net.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

#include <net/net_namespace.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/protocol.h>
#include <net/tcp.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/ax25.h>
#include <net/netrom.h>
#include <net/dst_metadata.h>
#include <net/ip_tunnels.h>

#include <linux/uaccess.h>

#include <linux/netfilter_arp.h>

/*
 *	Interface to generic neighbour cache.
 */
static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd);
static bool arp_key_eq(const struct neighbour *n, const void *pkey);
static int arp_constructor(struct neighbour *neigh);
static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
static void parp_redo(struct sk_buff *skb);
static int arp_is_multicast(const void *pkey);

static const struct neigh_ops arp_generic_ops = {
	.family =		AF_INET,
	.solicit =		arp_solicit,
	.error_report =		arp_error_report,
	.output =		neigh_resolve_output,
	.connected_output =	neigh_connected_output,
};

static const struct neigh_ops arp_hh_ops = {
	.family =		AF_INET,
	.solicit =		arp_solicit,
	.error_report =		arp_error_report,
	.output =		neigh_resolve_output,
	.connected_output =	neigh_resolve_output,
};

static const struct neigh_ops arp_direct_ops = {
	.family =		AF_INET,
	.output =		neigh_direct_output,
	.connected_output =	neigh_direct_output,
};

struct neigh_table arp_tbl = {
	.family		= AF_INET,
	.key_len	= 4,
	.protocol	= cpu_to_be16(ETH_P_IP),
	.hash		= arp_hash,
	.key_eq		= arp_key_eq,
	.constructor	= arp_constructor,
	.proxy_redo	= parp_redo,
	.is_multicast	= arp_is_multicast,
	.id		= "arp_cache",
	.parms		= {
		.tbl			= &arp_tbl,
		.reachable_time		= 30 * HZ,
		.data	= {
			[NEIGH_VAR_MCAST_PROBES] = 3,
			[NEIGH_VAR_UCAST_PROBES] = 3,
			[NEIGH_VAR_RETRANS_TIME] = 1 * HZ,
			[NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
			[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
			[NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ,
			[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
			[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
			[NEIGH_VAR_PROXY_QLEN] = 64,
			[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
			[NEIGH_VAR_PROXY_DELAY]	= (8 * HZ) / 10,
			[NEIGH_VAR_LOCKTIME] = 1 * HZ,
		},
	},
	.gc_interval	= 30 * HZ,
	.gc_thresh1	= 128,
	.gc_thresh2	= 512,
	.gc_thresh3	= 1024,
};
EXPORT_SYMBOL(arp_tbl);

int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
{
	switch (dev->type) {
	case ARPHRD_ETHER:
	case ARPHRD_FDDI:
	case ARPHRD_IEEE802:
		ip_eth_mc_map(addr, haddr);
		return 0;
	case ARPHRD_INFINIBAND:
		ip_ib_mc_map(addr, dev->broadcast, haddr);
		return 0;
	case ARPHRD_IPGRE:
		ip_ipgre_mc_map(addr, dev->broadcast, haddr);
		return 0;
	default:
		if (dir) {
			memcpy(haddr, dev->broadcast, dev->addr_len);
			return 0;
		}
	}
	return -EINVAL;
}


static u32 arp_hash(const void *pkey,
		    const struct net_device *dev,
		    __u32 *hash_rnd)
{
	return arp_hashfn(pkey, dev, hash_rnd);
}

static bool arp_key_eq(const struct neighbour *neigh, const void *pkey)
{
	return neigh_key_eq32(neigh, pkey);
}

static int arp_constructor(struct neighbour *neigh)
{
	__be32 addr;
	struct net_device *dev = neigh->dev;
	struct in_device *in_dev;
	struct neigh_parms *parms;
	u32 inaddr_any = INADDR_ANY;

	if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))
		memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len);

	addr = *(__be32 *)neigh->primary_key;
	rcu_read_lock();
	in_dev = __in_dev_get_rcu(dev);
	if (!in_dev) {
		rcu_read_unlock();
		return -EINVAL;
	}

	neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr);

	parms = in_dev->arp_parms;
	__neigh_parms_put(neigh->parms);
	neigh->parms = neigh_parms_clone(parms);
	rcu_read_unlock();

	if (!dev->header_ops) {
		neigh->nud_state = NUD_NOARP;
		neigh->ops = &arp_direct_ops;
		neigh->output = neigh_direct_output;
	} else {
		/* Good devices (checked by reading texts, but only Ethernet is
		   tested)

		   ARPHRD_ETHER: (ethernet, apfddi)
		   ARPHRD_FDDI: (fddi)
		   ARPHRD_IEEE802: (tr)
		   ARPHRD_METRICOM: (strip)
		   ARPHRD_ARCNET:
		   etc. etc. etc.

		   ARPHRD_IPDDP will also work, if author repairs it.
		   I did not it, because this driver does not work even
		   in old paradigm.
		 */

		if (neigh->type == RTN_MULTICAST) {
			neigh->nud_state = NUD_NOARP;
			arp_mc_map(addr, neigh->ha, dev, 1);
		} else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) {
			neigh->nud_state = NUD_NOARP;
			memcpy(neigh->ha, dev->dev_addr,