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linux/net/ipv4/arp.c
David Ahern 859bd2ef1f net: Evict neighbor entries on carrier down 
When a link's carrier goes down it could be a sign of the port changing
networks. If the new network has overlapping addresses with the old one,
then the kernel will continue trying to use neighbor entries established
based on the old network until the entries finally age out - meaning a
potentially long delay with communications not working.

This patch evicts neighbor entries on carrier down with the exception of
those marked permanent. Permanent entries are managed by userspace (either
an admin or a routing daemon such as FRR).

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-10-12 09:47:39 -07:00

1456 lines
36 KiB
C
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/* 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).
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* 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 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,
.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_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, dev->addr_len);
} else if (neigh->type == RTN_BROADCAST ||
(dev->flags & IFF_POINTOPOINT)) {
neigh->nud_state = NUD_NOARP;
memcpy(neigh->ha, dev->broadcast, dev->addr_len);
}
if (dev->header_ops->cache)
neigh->ops = &arp_hh_ops;
else
neigh->ops = &arp_generic_ops;
if (neigh->nud_state & NUD_VALID)
neigh->output = neigh->ops->connected_output;
else
neigh->output = neigh->ops->output;
}
return 0;
}
static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
dst_link_failure(skb);
kfree_skb(skb);
}
/* Create and send an arp packet. */
static void arp_send_dst(int type, int ptype, __be32 dest_ip,
struct net_device *dev, __be32 src_ip,
const unsigned char *dest_hw,
const unsigned char *src_hw,
const unsigned char *target_hw,
struct dst_entry *dst)
{
struct sk_buff *skb;
/* arp on this interface. */
if (dev->flags & IFF_NOARP)
return;
skb = arp_create(type, ptype, dest_ip, dev, src_ip,
dest_hw, src_hw, target_hw);
if (!skb)
return;
skb_dst_set(skb, dst_clone(dst));
arp_xmit(skb);
}
void arp_send(int type, int ptype, __be32 dest_ip,
struct net_device *dev, __be32 src_ip,
const unsigned char *dest_hw, const unsigned char *src_hw,
const unsigned char *target_hw)
{
arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw,
target_hw, NULL);
}
EXPORT_SYMBOL(arp_send);
static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
{
__be32 saddr = 0;
u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
struct net_device *dev = neigh->dev;
__be32 target = *(__be32 *)neigh->primary_key;
int probes = atomic_read(&neigh->probes);
struct in_device *in_dev;
struct dst_entry *dst = NULL;
rcu_read_lock();
in_dev = __in_dev_get_rcu(dev);
if (!in_dev) {
rcu_read_unlock();
return;
}
switch (IN_DEV_ARP_ANNOUNCE(in_dev)) {
default:
case 0: /* By default announce any local IP */
if (skb && inet_addr_type_dev_table(dev_net(dev), dev,
ip_hdr(skb)->saddr) == RTN_LOCAL)
saddr = ip_hdr(skb)->saddr;
break;
case 1: /* Restrict announcements of saddr in same subnet */
if (!skb)
break;
saddr = ip_hdr(skb)->saddr;
if (inet_addr_type_dev_table(dev_net(dev), dev,
saddr) == RTN_LOCAL) {
/* saddr should be known to target */
if (inet_addr_onlink(in_dev, target, saddr))
break;
}
saddr = 0;
break;
case 2: /* Avoid secondary IPs, get a primary/preferred one */
break;
}
rcu_read_unlock();
if (!saddr)
saddr = inet_select_addr(dev, target, RT_SCOPE_LINK);
probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
if (probes < 0) {
if (!(neigh->nud_state & NUD_VALID))
pr_debug("trying to ucast probe in NUD_INVALID\n");
neigh_ha_snapshot(dst_ha, neigh, dev);
dst_hw = dst_ha;
} else {
probes -= NEIGH_VAR(neigh->parms, APP_PROBES);
if (probes < 0) {
neigh_app_ns(neigh);
return;
}
}
if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE))
dst = skb_dst(skb);
arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
dst_hw, dev->dev_addr, NULL, dst);
}
static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
{
struct net *net = dev_net(in_dev->dev);
int scope;
switch (IN_DEV_ARP_IGNORE(in_dev)) {
case 0: /* Reply, the tip is already validated */
return 0;
case 1: /* Reply only if tip is configured on the incoming interface */
sip = 0;
scope = RT_SCOPE_HOST;
break;
case 2: /*
* Reply only if tip is configured on the incoming interface
* and is in same subnet as sip
*/
scope = RT_SCOPE_HOST;
break;
case 3: /* Do not reply for scope host addresses */
sip = 0;
scope = RT_SCOPE_LINK;
in_dev = NULL;
break;
case 4: /* Reserved */
case 5:
case 6:
case 7:
return 0;
case 8: /* Do not reply */
return 1;
default:
return 0;
}
return !inet_confirm_addr(net, in_dev, sip, tip, scope);
}
static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev)
{
struct rtable *rt;
int flag = 0;
/*unsigned long now; */
struct net *net = dev_net(dev);
rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev));
if (IS_ERR(rt))
return 1;
if (rt->dst.dev != dev) {
__NET_INC_STATS(net, LINUX_MIB_ARPFILTER);
flag = 1;
}
ip_rt_put(rt);
return flag;
}
/*
* Check if we can use proxy ARP for this path
*/
static inline int arp_fwd_proxy(struct in_device *in_dev,
struct net_device *dev, struct rtable *rt)
{
struct in_device *out_dev;
int imi, omi = -1;
if (rt->dst.dev == dev)
return 0;
if (!IN_DEV_PROXY_ARP(in_dev))
return 0;
imi = IN_DEV_MEDIUM_ID(in_dev);
if (imi == 0)
return 1;
if (imi == -1)
return 0;
/* place to check for proxy_arp for routes */
out_dev = __in_dev_get_rcu(rt->dst.dev);
if (out_dev)
omi = IN_DEV_MEDIUM_ID(out_dev);
return omi != imi && omi != -1;
}
/*
* Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
*
* RFC3069 supports proxy arp replies back to the same interface. This
* is done to support (ethernet) switch features, like RFC 3069, where
* the individual ports are not allowed to communicate with each
* other, BUT they are allowed to talk to the upstream router. As
* described in RFC 3069, it is possible to allow these hosts to
* communicate through the upstream router, by proxy_arp'ing.
*
* RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
*
* This technology is known by different names:
* In RFC 3069 it is called VLAN Aggregation.
* Cisco and Allied Telesyn call it Private VLAN.
* Hewlett-Packard call it Source-Port filtering or port-isolation.
* Ericsson call it MAC-Forced Forwarding (RFC Draft).
*
*/
static inline int arp_fwd_pvlan(struct in_device *in_dev,
struct net_device *dev, struct rtable *rt,
__be32 sip, __be32 tip)
{
/* Private VLAN is only concerned about the same ethernet segment */
if (rt->dst.dev != dev)
return 0;
/* Don't reply on self probes (often done by windowz boxes)*/
if (sip == tip)
return 0;
if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
return 1;
else
return 0;
}
/*
* Interface to link layer: send routine and receive handler.
*/
/*
* Create an arp packet. If dest_hw is not set, we create a broadcast
* message.
*/
struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
struct net_device *dev, __be32 src_ip,
const unsigned char *dest_hw,
const unsigned char *src_hw,
const unsigned char *target_hw)
{
struct sk_buff *skb;
struct arphdr *arp;
unsigned char *arp_ptr;
int hlen = LL_RESERVED_SPACE(dev);
int tlen = dev->needed_tailroom;
/*
* Allocate a buffer
*/
skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC);
if (!skb)
return NULL;
skb_reserve(skb, hlen);
skb_reset_network_header(skb);
arp = skb_put(skb, arp_hdr_len(dev));
skb->dev = dev;
skb->protocol = htons(ETH_P_ARP);
if (!src_hw)
src_hw = dev->dev_addr;
if (!dest_hw)
dest_hw = dev->broadcast;
/*
* Fill the device header for the ARP frame
*/
if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0)
goto out;
/*
* Fill out the arp protocol part.
*
* The arp hardware type should match the device type, except for FDDI,
* which (according to RFC 1390) should always equal 1 (Ethernet).
*/
/*
* Exceptions everywhere. AX.25 uses the AX.25 PID value not the
* DIX code for the protocol. Make these device structure fields.
*/
switch (dev->type) {
default:
arp->ar_hrd = htons(dev->type);
arp->ar_pro = htons(ETH_P_IP);
break;
#if IS_ENABLED(CONFIG_AX25)
case ARPHRD_AX25:
arp->ar_hrd = htons(ARPHRD_AX25);
arp->ar_pro = htons(AX25_P_IP);
break;
#if IS_ENABLED(CONFIG_NETROM)
case ARPHRD_NETROM:
arp->ar_hrd = htons(ARPHRD_NETROM);
arp->ar_pro = htons(AX25_P_IP);
break;
#endif
#endif
#if IS_ENABLED(CONFIG_FDDI)
case ARPHRD_FDDI:
arp->ar_hrd = htons(ARPHRD_ETHER);
arp->ar_pro = htons(ETH_P_IP);
break;
#endif
}
arp->ar_hln = dev->addr_len;
arp->ar_pln = 4;
arp->ar_op = htons(type);
arp_ptr = (unsigned char *)(arp + 1);
memcpy(arp_ptr, src_hw, dev->addr_len);
arp_ptr += dev->addr_len;
memcpy(arp_ptr, &src_ip, 4);
arp_ptr += 4;
switch (dev->type) {
#if IS_ENABLED(CONFIG_FIREWIRE_NET)
case ARPHRD_IEEE1394:
break;
#endif
default:
if (target_hw)
memcpy(arp_ptr, target_hw, dev->addr_len);
else
memset(arp_ptr, 0, dev->addr_len);
arp_ptr += dev->addr_len;
}
memcpy(arp_ptr, &dest_ip, 4);
return skb;
out:
kfree_skb(skb);
return NULL;
}
EXPORT_SYMBOL(arp_create);
static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
return dev_queue_xmit(skb);
}
/*
* Send an arp packet.
*/
void arp_xmit(struct sk_buff *skb)
{
/* Send it off, maybe filter it using firewalling first. */
NF_HOOK(NFPROTO_ARP, NF_ARP_OUT,
dev_net(skb->dev), NULL, skb, NULL, skb->dev,
arp_xmit_finish);
}
EXPORT_SYMBOL(arp_xmit);
static bool arp_is_garp(struct net *net, struct net_device *dev,
int *addr_type, __be16 ar_op,
__be32 sip, __be32 tip,
unsigned char *sha, unsigned char *tha)
{
bool is_garp = tip == sip;
/* Gratuitous ARP _replies_ also require target hwaddr to be
* the same as source.
*/
if (is_garp && ar_op == htons(ARPOP_REPLY))
is_garp =
/* IPv4 over IEEE 1394 doesn't provide target
* hardware address field in its ARP payload.
*/
tha &&
!memcmp(tha, sha, dev->addr_len);
if (is_garp) {
*addr_type = inet_addr_type_dev_table(net, dev, sip);
if (*addr_type != RTN_UNICAST)
is_garp = false;
}
return is_garp;
}
/*
* Process an arp request.
*/
static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
struct in_device *in_dev = __in_dev_get_rcu(dev);
struct arphdr *arp;
unsigned char *arp_ptr;
struct rtable *rt;
unsigned char *sha;
unsigned char *tha = NULL;
__be32 sip, tip;
u16 dev_type = dev->type;
int addr_type;
struct neighbour *n;
struct dst_entry *reply_dst = NULL;
bool is_garp = false;
/* arp_rcv below verifies the ARP header and verifies the device
* is ARP'able.
*/
if (!in_dev)
goto out_free_skb;
arp = arp_hdr(skb);
switch (dev_type) {
default:
if (arp->ar_pro != htons(ETH_P_IP) ||
htons(dev_type) != arp->ar_hrd)
goto out_free_skb;
break;
case ARPHRD_ETHER:
case ARPHRD_FDDI:
case ARPHRD_IEEE802:
/*
* ETHERNET, and Fibre Channel (which are IEEE 802
* devices, according to RFC 2625) devices will accept ARP
* hardware types of either 1 (Ethernet) or 6 (IEEE 802.2).
* This is the case also of FDDI, where the RFC 1390 says that
* FDDI devices should accept ARP hardware of (1) Ethernet,
* however, to be more robust, we'll accept both 1 (Ethernet)
* or 6 (IEEE 802.2)
*/
if ((arp->ar_hrd != htons(ARPHRD_ETHER) &&
arp->ar_hrd != htons(ARPHRD_IEEE802)) ||
arp->ar_pro != htons(ETH_P_IP))
goto out_free_skb;
break;
case ARPHRD_AX25:
if (arp->ar_pro != htons(AX25_P_IP) ||
arp->ar_hrd != htons(ARPHRD_AX25))
goto out_free_skb;
break;
case ARPHRD_NETROM:
if (arp->ar_pro != htons(AX25_P_IP) ||
arp->ar_hrd != htons(ARPHRD_NETROM))
goto out_free_skb;
break;
}
/* Understand only these message types */
if (arp->ar_op != htons(ARPOP_REPLY) &&
arp->ar_op != htons(ARPOP_REQUEST))
goto out_free_skb;
/*
* Extract fields
*/
arp_ptr = (unsigned char *)(arp + 1);
sha = arp_ptr;
arp_ptr += dev->addr_len;
memcpy(&sip, arp_ptr, 4);
arp_ptr += 4;
switch (dev_type) {
#if IS_ENABLED(CONFIG_FIREWIRE_NET)
case ARPHRD_IEEE1394:
break;
#endif
default:
tha = arp_ptr;
arp_ptr += dev->addr_len;
}
memcpy(&tip, arp_ptr, 4);
/*
* Check for bad requests for 127.x.x.x and requests for multicast
* addresses. If this is one such, delete it.
*/
if (ipv4_is_multicast(tip) ||
(!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
goto out_free_skb;
/*
* For some 802.11 wireless deployments (and possibly other networks),
* there will be an ARP proxy and gratuitous ARP frames are attacks
* and thus should not be accepted.
*/
if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
goto out_free_skb;
/*
* Special case: We must set Frame Relay source Q.922 address
*/
if (dev_type == ARPHRD_DLCI)
sha = dev->broadcast;
/*
* Process entry. The idea here is we want to send a reply if it is a
* request for us or if it is a request for someone else that we hold
* a proxy for. We want to add an entry to our cache if it is a reply
* to us or if it is a request for our address.
* (The assumption for this last is that if someone is requesting our
* address, they are probably intending to talk to us, so it saves time
* if we cache their address. Their address is also probably not in
* our cache, since ours is not in their cache.)
*
* Putting this another way, we only care about replies if they are to
* us, in which case we add them to the cache. For requests, we care
* about those for us and those for our proxies. We reply to both,
* and in the case of requests for us we add the requester to the arp
* cache.
*/
if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb))
reply_dst = (struct dst_entry *)
iptunnel_metadata_reply(skb_metadata_dst(skb),
GFP_ATOMIC);
/* Special case: IPv4 duplicate address detection packet (RFC2131) */
if (sip == 0) {
if (arp->ar_op == htons(ARPOP_REQUEST) &&
inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
!arp_ignore(in_dev, sip, tip))
arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip,
sha, dev->dev_addr, sha, reply_dst);
goto out_consume_skb;
}
if (arp->ar_op == htons(ARPOP_REQUEST) &&
ip_route_input_noref(skb, tip, sip, 0, dev) == 0) {
rt = skb_rtable(skb);
addr_type = rt->rt_type;
if (addr_type == RTN_LOCAL) {
int dont_send;
dont_send = arp_ignore(in_dev, sip, tip);
if (!dont_send && IN_DEV_ARPFILTER(in_dev))
dont_send = arp_filter(sip, tip, dev);
if (!dont_send) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n) {
arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
sip, dev, tip, sha,
dev->dev_addr, sha,
reply_dst);
neigh_release(n);
}
}
goto out_consume_skb;
} else if (IN_DEV_FORWARD(in_dev)) {
if (addr_type == RTN_UNICAST &&
(arp_fwd_proxy(in_dev, dev, rt) ||
arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
(rt->dst.dev != dev &&
pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n)
neigh_release(n);
if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED ||
skb->pkt_type == PACKET_HOST ||
NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) {
arp_send_dst(ARPOP_REPLY, ETH_P_ARP,
sip, dev, tip, sha,
dev->dev_addr, sha,
reply_dst);
} else {
pneigh_enqueue(&arp_tbl,
in_dev->arp_parms, skb);
goto out_free_dst;
}
goto out_consume_skb;
}
}
}
/* Update our ARP tables */
n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
addr_type = -1;
if (n || IN_DEV_ARP_ACCEPT(in_dev)) {
is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op,
sip, tip, sha, tha);
}
if (IN_DEV_ARP_ACCEPT(in_dev)) {
/* Unsolicited ARP is not accepted by default.
It is possible, that this option should be enabled for some
devices (strip is candidate)
*/
if (!n &&
(is_garp ||
(arp->ar_op == htons(ARPOP_REPLY) &&
(addr_type == RTN_UNICAST ||
(addr_type < 0 &&
/* postpone calculation to as late as possible */
inet_addr_type_dev_table(net, dev, sip) ==
RTN_UNICAST)))))
n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
}
if (n) {
int state = NUD_REACHABLE;
int override;
/* If several different ARP replies follows back-to-back,
use the FIRST one. It is possible, if several proxy
agents are active. Taking the first reply prevents
arp trashing and chooses the fastest router.
*/
override = time_after(jiffies,
n->updated +
NEIGH_VAR(n->parms, LOCKTIME)) ||
is_garp;
/* Broadcast replies and request packets
do not assert neighbour reachability.
*/
if (arp->ar_op != htons(ARPOP_REPLY) ||
skb->pkt_type != PACKET_HOST)
state = NUD_STALE;
neigh_update(n, sha, state,
override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0);
neigh_release(n);
}
out_consume_skb:
consume_skb(skb);
out_free_dst:
dst_release(reply_dst);
return NET_RX_SUCCESS;
out_free_skb:
kfree_skb(skb);
return NET_RX_DROP;
}
static void parp_redo(struct sk_buff *skb)
{
arp_process(dev_net(skb->dev), NULL, skb);
}
/*
* Receive an arp request from the device layer.
*/
static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
const struct arphdr *arp;
/* do not tweak dropwatch on an ARP we will ignore */
if (dev->flags & IFF_NOARP ||
skb->pkt_type == PACKET_OTHERHOST ||
skb->pkt_type == PACKET_LOOPBACK)
goto consumeskb;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
goto out_of_mem;
/* ARP header, plus 2 device addresses, plus 2 IP addresses. */
if (!pskb_may_pull(skb, arp_hdr_len(dev)))
goto freeskb;
arp = arp_hdr(skb);
if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4)
goto freeskb;
memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
return NF_HOOK(NFPROTO_ARP, NF_ARP_IN,
dev_net(dev), NULL, skb, dev, NULL,
arp_process);
consumeskb:
consume_skb(skb);
return NET_RX_SUCCESS;
freeskb:
kfree_skb(skb);
out_of_mem:
return NET_RX_DROP;
}
/*
* User level interface (ioctl)
*/
/*
* Set (create) an ARP cache entry.
*/
static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on)
{
if (!dev) {
IPV4_DEVCONF_ALL(net, PROXY_ARP) = on;
return 0;
}
if (__in_dev_get_rtnl(dev)) {
IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on);
return 0;
}
return -ENXIO;
}
static int arp_req_set_public(struct net *net, struct arpreq *r,
struct net_device *dev)
{
__be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
if (mask && mask != htonl(0xFFFFFFFF))
return -EINVAL;
if (!dev && (r->arp_flags & ATF_COM)) {
dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family,
r->arp_ha.sa_data);
if (!dev)
return -ENODEV;
}
if (mask) {
if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1))
return -ENOBUFS;
return 0;
}
return arp_req_set_proxy(net, dev, 1);
}
static int arp_req_set(struct net *net, struct arpreq *r,
struct net_device *dev)
{
__be32 ip;
struct neighbour *neigh;
int err;
if (r->arp_flags & ATF_PUBL)
return arp_req_set_public(net, r, dev);
ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
if (r->arp_flags & ATF_PERM)
r->arp_flags |= ATF_COM;
if (!dev) {
struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
if (IS_ERR(rt))
return PTR_ERR(rt);
dev = rt->dst.dev;
ip_rt_put(rt);
if (!dev)
return -EINVAL;
}
switch (dev->type) {
#if IS_ENABLED(CONFIG_FDDI)
case ARPHRD_FDDI:
/*
* According to RFC 1390, FDDI devices should accept ARP
* hardware types of 1 (Ethernet). However, to be more
* robust, we'll accept hardware types of either 1 (Ethernet)
* or 6 (IEEE 802.2).
*/
if (r->arp_ha.sa_family != ARPHRD_FDDI &&
r->arp_ha.sa_family != ARPHRD_ETHER &&
r->arp_ha.sa_family != ARPHRD_IEEE802)
return -EINVAL;
break;
#endif
default:
if (r->arp_ha.sa_family != dev->type)
return -EINVAL;
break;
}
neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev);
err = PTR_ERR(neigh);
if (!IS_ERR(neigh)) {
unsigned int state = NUD_STALE;
if (r->arp_flags & ATF_PERM)
state = NUD_PERMANENT;
err = neigh_update(neigh, (r->arp_flags & ATF_COM) ?
r->arp_ha.sa_data : NULL, state,
NEIGH_UPDATE_F_OVERRIDE |
NEIGH_UPDATE_F_ADMIN, 0);
neigh_release(neigh);
}
return err;
}
static unsigned int arp_state_to_flags(struct neighbour *neigh)
{
if (neigh->nud_state&NUD_PERMANENT)
return ATF_PERM | ATF_COM;
else if (neigh->nud_state&NUD_VALID)
return ATF_COM;
else
return 0;
}
/*
* Get an ARP cache entry.
*/
static int arp_req_get(struct arpreq *r, struct net_device *dev)
{
__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
struct neighbour *neigh;
int err = -ENXIO;
neigh = neigh_lookup(&arp_tbl, &ip, dev);
if (neigh) {
if (!(neigh->nud_state & NUD_NOARP)) {
read_lock_bh(&neigh->lock);
memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
r->arp_flags = arp_state_to_flags(neigh);
read_unlock_bh(&neigh->lock);
r->arp_ha.sa_family = dev->type;
strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
err = 0;
}
neigh_release(neigh);
}
return err;
}
static int arp_invalidate(struct net_device *dev, __be32 ip)
{
struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
int err = -ENXIO;
struct neigh_table *tbl = &arp_tbl;
if (neigh) {
if (neigh->nud_state & ~NUD_NOARP)
err = neigh_update(neigh, NULL, NUD_FAILED,
NEIGH_UPDATE_F_OVERRIDE|
NEIGH_UPDATE_F_ADMIN, 0);
write_lock_bh(&tbl->lock);
neigh_release(neigh);
neigh_remove_one(neigh, tbl);
write_unlock_bh(&tbl->lock);
}
return err;
}
static int arp_req_delete_public(struct net *net, struct arpreq *r,
struct net_device *dev)
{
__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
__be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr;
if (mask == htonl(0xFFFFFFFF))
return pneigh_delete(&arp_tbl, net, &ip, dev);
if (mask)
return -EINVAL;
return arp_req_set_proxy(net, dev, 0);
}
static int arp_req_delete(struct net *net, struct arpreq *r,
struct net_device *dev)
{
__be32 ip;
if (r->arp_flags & ATF_PUBL)
return arp_req_delete_public(net, r, dev);
ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
if (!dev) {
struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0);
if (IS_ERR(rt))
return PTR_ERR(rt);
dev = rt->dst.dev;
ip_rt_put(rt);
if (!dev)
return -EINVAL;
}
return arp_invalidate(dev, ip);
}
/*
* Handle an ARP layer I/O control request.
*/
int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
{
int err;
struct arpreq r;
struct net_device *dev = NULL;
switch (cmd) {
case SIOCDARP:
case SIOCSARP:
if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
return -EPERM;
/* fall through */
case SIOCGARP:
err = copy_from_user(&r, arg, sizeof(struct arpreq));
if (err)
return -EFAULT;
break;
default:
return -EINVAL;
}
if (r.arp_pa.sa_family != AF_INET)
return -EPFNOSUPPORT;
if (!(r.arp_flags & ATF_PUBL) &&
(r.arp_flags & (ATF_NETMASK | ATF_DONTPUB)))
return -EINVAL;
if (!(r.arp_flags & ATF_NETMASK))
((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr =
htonl(0xFFFFFFFFUL);
rtnl_lock();
if (r.arp_dev[0]) {
err = -ENODEV;
dev = __dev_get_by_name(net, r.arp_dev);
if (!dev)
goto out;
/* Mmmm... It is wrong... ARPHRD_NETROM==0 */
if (!r.arp_ha.sa_family)
r.arp_ha.sa_family = dev->type;
err = -EINVAL;
if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
goto out;
} else if (cmd == SIOCGARP) {
err = -ENODEV;
goto out;
}
switch (cmd) {
case SIOCDARP:
err = arp_req_delete(net, &r, dev);
break;
case SIOCSARP:
err = arp_req_set(net, &r, dev);
break;
case SIOCGARP:
err = arp_req_get(&r, dev);
break;
}
out:
rtnl_unlock();
if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
err = -EFAULT;
return err;
}
static int arp_netdev_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct netdev_notifier_change_info *change_info;
switch (event) {
case NETDEV_CHANGEADDR:
neigh_changeaddr(&arp_tbl, dev);
rt_cache_flush(dev_net(dev));
break;
case NETDEV_CHANGE:
change_info = ptr;
if (change_info->flags_changed & IFF_NOARP)
neigh_changeaddr(&arp_tbl, dev);
if (!netif_carrier_ok(dev))
neigh_carrier_down(&arp_tbl, dev);
break;
default:
break;
}
return NOTIFY_DONE;
}
static struct notifier_block arp_netdev_notifier = {
.notifier_call = arp_netdev_event,
};
/* Note, that it is not on notifier chain.
It is necessary, that this routine was called after route cache will be
flushed.
*/
void arp_ifdown(struct net_device *dev)
{
neigh_ifdown(&arp_tbl, dev);
}
/*
* Called once on startup.
*/
static struct packet_type arp_packet_type __read_mostly = {
.type = cpu_to_be16(ETH_P_ARP),
.func = arp_rcv,
};
static int arp_proc_init(void);
void __init arp_init(void)
{
neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
dev_add_pack(&arp_packet_type);
arp_proc_init();
#ifdef CONFIG_SYSCTL
neigh_sysctl_register(NULL, &arp_tbl.parms, NULL);
#endif
register_netdevice_notifier(&arp_netdev_notifier);
}
#ifdef CONFIG_PROC_FS
#if IS_ENABLED(CONFIG_AX25)
/* ------------------------------------------------------------------------ */
/*
* ax25 -> ASCII conversion
*/
static void ax2asc2(ax25_address *a, char *buf)
{
char c, *s;
int n;
for (n = 0, s = buf; n < 6; n++) {
c = (a->ax25_call[n] >> 1) & 0x7F;
if (c != ' ')
*s++ = c;
}
*s++ = '-';
n = (a->ax25_call[6] >> 1) & 0x0F;
if (n > 9) {
*s++ = '1';
n -= 10;
}
*s++ = n + '0';
*s++ = '\0';
if (*buf == '\0' || *buf == '-') {
buf[0] = '*';
buf[1] = '\0';
}
}
#endif /* CONFIG_AX25 */
#define HBUFFERLEN 30
static void arp_format_neigh_entry(struct seq_file *seq,
struct neighbour *n)
{
char hbuffer[HBUFFERLEN];
int k, j;
char tbuf[16];
struct net_device *dev = n->dev;
int hatype = dev->type;
read_lock(&n->lock);
/* Convert hardware address to XX:XX:XX:XX ... form. */
#if IS_ENABLED(CONFIG_AX25)
if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM)
ax2asc2((ax25_address *)n->ha, hbuffer);
else {
#endif
for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
hbuffer[k++] = hex_asc_hi(n->ha[j]);
hbuffer[k++] = hex_asc_lo(n->ha[j]);
hbuffer[k++] = ':';
}
if (k != 0)
--k;
hbuffer[k] = 0;
#if IS_ENABLED(CONFIG_AX25)
}
#endif
sprintf(tbuf, "%pI4", n->primary_key);
seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n",
tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
read_unlock(&n->lock);
}
static void arp_format_pneigh_entry(struct seq_file *seq,
struct pneigh_entry *n)
{
struct net_device *dev = n->dev;
int hatype = dev ? dev->type : 0;
char tbuf[16];
sprintf(tbuf, "%pI4", n->key);
seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n",
tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00",
dev ? dev->name : "*");
}
static int arp_seq_show(struct seq_file *seq, void *v)
{
if (v == SEQ_START_TOKEN) {
seq_puts(seq, "IP address HW type Flags "
"HW address Mask Device\n");
} else {
struct neigh_seq_state *state = seq->private;
if (state->flags & NEIGH_SEQ_IS_PNEIGH)
arp_format_pneigh_entry(seq, v);
else
arp_format_neigh_entry(seq, v);
}
return 0;
}
static void *arp_seq_start(struct seq_file *seq, loff_t *pos)
{
/* Don't want to confuse "arp -a" w/ magic entries,
* so we tell the generic iterator to skip NUD_NOARP.
*/
return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP);
}
/* ------------------------------------------------------------------------ */
static const struct seq_operations arp_seq_ops = {
.start = arp_seq_start,
.next = neigh_seq_next,
.stop = neigh_seq_stop,
.show = arp_seq_show,
};
/* ------------------------------------------------------------------------ */
static int __net_init arp_net_init(struct net *net)
{
if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
sizeof(struct neigh_seq_state)))
return -ENOMEM;
return 0;
}
static void __net_exit arp_net_exit(struct net *net)
{
remove_proc_entry("arp", net->proc_net);
}
static struct pernet_operations arp_net_ops = {
.init = arp_net_init,
.exit = arp_net_exit,
};
static int __init arp_proc_init(void)
{
return register_pernet_subsys(&arp_net_ops);
}
#else /* CONFIG_PROC_FS */
static int __init arp_proc_init(void)
{
return 0;
}
#endif /* CONFIG_PROC_FS */
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