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linux/net/ipv4/arp.c
YOSHIFUJI Hideaki / 吉藤英明 6752c8db8e firewire net, ipv4 arp: Extend hardware address and remove driver-level packet inspection. 
Inspection of upper layer protocol is considered harmful, especially
if it is about ARP or other stateful upper layer protocol; driver
cannot (and should not) have full state of them.

IPv4 over Firewire module used to inspect ARP (both in sending path
and in receiving path), and record peer's GUID, max packet size, max
speed and fifo address.  This patch removes such inspection by extending
our "hardware address" definition to include other information as well:
max packet size, max speed and fifo.  By doing this, The neighbour
module in networking subsystem can cache them.

Note: As we have started ignoring sspd and max_rec in ARP/NDP, those
      information will not be used in the driver when sending.

When a packet is being sent, the IP layer fills our pseudo header with
the extended "hardware address", including GUID and fifo.  The driver
can look-up node-id (the real but rather volatile low-level address)
by GUID, and then the module can send the packet to the wire using
parameters provided in the extendedn hardware address.

This approach is realistic because IP over IEEE1394 (RFC2734) and IPv6
over IEEE1394 (RFC3146) share same "hardware address" format
in their address resolution protocols.

Here, extended "hardware address" is defined as follows:

union fwnet_hwaddr {
	u8 u[16];
	struct {
		__be64 uniq_id;		/* EUI-64			*/
		u8 max_rec;		/* max packet size		*/
		u8 sspd;		/* max speed			*/
		__be16 fifo_hi;		/* hi 16bits of FIFO addr	*/
		__be32 fifo_lo;		/* lo 32bits of FIFO addr	*/
	} __packed uc;
};

Note that Hardware address is declared as union, so that we can map full
IP address into this, when implementing MCAP (Multicast Cannel Allocation
Protocol) for IPv6, but IP and ARP subsystem do not need to know this
format in detail.

One difference between original ARP (RFC826) and 1394 ARP (RFC2734)
is that 1394 ARP Request/Reply do not contain the target hardware address
field (aka ar$tha).  This difference is handled in the ARP subsystem.

CC: Stephan Gatzka <stephan.gatzka@gmail.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-26 12:32:13 -04:00

1451 lines
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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 <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 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,
};
static const struct neigh_ops arp_broken_ops = {
.family = AF_INET,
.solicit = arp_solicit,
.error_report = arp_error_report,
.output = neigh_compat_output,
.connected_output = neigh_compat_output,
};
struct neigh_table arp_tbl = {
.family = AF_INET,
.key_len = 4,
.hash = arp_hash,
.constructor = arp_constructor,
.proxy_redo = parp_redo,
.id = "arp_cache",
.parms = {
.tbl = &arp_tbl,
.base_reachable_time = 30 * HZ,
.retrans_time = 1 * HZ,
.gc_staletime = 60 * HZ,
.reachable_time = 30 * HZ,
.delay_probe_time = 5 * HZ,
.queue_len_bytes = 64*1024,
.ucast_probes = 3,
.mcast_probes = 3,
.anycast_delay = 1 * HZ,
.proxy_delay = (8 * HZ) / 10,
.proxy_qlen = 64,
.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(*(u32 *)pkey, dev, *hash_rnd);
}
static int arp_constructor(struct neighbour *neigh)
{
__be32 addr = *(__be32 *)neigh->primary_key;
struct net_device *dev = neigh->dev;
struct in_device *in_dev;
struct neigh_parms *parms;
rcu_read_lock();
in_dev = __in_dev_get_rcu(dev);
if (in_dev == NULL) {
rcu_read_unlock();
return -EINVAL;
}
neigh->type = inet_addr_type(dev_net(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 1
/* So... these "amateur" devices are hopeless.
The only thing, that I can say now:
It is very sad that we need to keep ugly obsolete
code to make them happy.
They should be moved to more reasonable state, now
they use rebuild_header INSTEAD OF hard_start_xmit!!!
Besides that, they are sort of out of date
(a lot of redundant clones/copies, useless in 2.1),
I wonder why people believe that they work.
*/
switch (dev->type) {
default:
break;
case ARPHRD_ROSE:
#if IS_ENABLED(CONFIG_AX25)
case ARPHRD_AX25:
#if IS_ENABLED(CONFIG_NETROM)
case ARPHRD_NETROM:
#endif
neigh->ops = &arp_broken_ops;
neigh->output = neigh->ops->output;
return 0;
#else
break;
#endif
}
#endif
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);
}
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;
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_net(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_net(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->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->parms->app_probes;
if (probes < 0) {
#ifdef CONFIG_ARPD
neigh_app_ns(neigh);
#endif
return;
}
}
arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
dst_hw, dev->dev_addr, NULL);
}
static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)
{
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;
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(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, 0);
if (IS_ERR(rt))
return 1;
if (rt->dst.dev != dev) {
NET_INC_STATS_BH(net, LINUX_MIB_ARPFILTER);
flag = 1;
}
ip_rt_put(rt);
return flag;
}
/* OBSOLETE FUNCTIONS */
/*
* Find an arp mapping in the cache. If not found, post a request.
*
* It is very UGLY routine: it DOES NOT use skb->dst->neighbour,
* even if it exists. It is supposed that skb->dev was mangled
* by a virtual device (eql, shaper). Nobody but broken devices
* is allowed to use this function, it is scheduled to be removed. --ANK
*/
static int arp_set_predefined(int addr_hint, unsigned char *haddr,
__be32 paddr, struct net_device *dev)
{
switch (addr_hint) {
case RTN_LOCAL:
pr_debug("arp called for own IP address\n");
memcpy(haddr, dev->dev_addr, dev->addr_len);
return 1;
case RTN_MULTICAST:
arp_mc_map(paddr, haddr, dev, 1);
return 1;
case RTN_BROADCAST:
memcpy(haddr, dev->broadcast, dev->addr_len);
return 1;
}
return 0;
}
int arp_find(unsigned char *haddr, struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
__be32 paddr;
struct neighbour *n;
if (!skb_dst(skb)) {
pr_debug("arp_find is called with dst==NULL\n");
kfree_skb(skb);
return 1;
}
paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr);
if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
paddr, dev))
return 0;
n = __neigh_lookup(&arp_tbl, &paddr, dev, 1);
if (n) {
n->used = jiffies;
if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) {
neigh_ha_snapshot(haddr, n, dev);
neigh_release(n);
return 0;
}
neigh_release(n);
} else
kfree_skb(skb);
return 1;
}
EXPORT_SYMBOL(arp_find);
/* END OF OBSOLETE FUNCTIONS */
/*
* 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 == NULL), 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 == NULL)
return NULL;
skb_reserve(skb, hlen);
skb_reset_network_header(skb);
arp = (struct arphdr *) skb_put(skb, arp_hdr_len(dev));
skb->dev = dev;
skb->protocol = htons(ETH_P_ARP);
if (src_hw == NULL)
src_hw = dev->dev_addr;
if (dest_hw == NULL)
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 != NULL)
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);
/*
* 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, skb, NULL, skb->dev, dev_queue_xmit);
}
EXPORT_SYMBOL(arp_xmit);
/*
* Create and send an arp packet.
*/
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)
{
struct sk_buff *skb;
/*
* No 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 == NULL)
return;
arp_xmit(skb);
}
EXPORT_SYMBOL(arp_send);
/*
* Process an arp request.
*/
static int arp_process(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;
__be32 sip, tip;
u16 dev_type = dev->type;
int addr_type;
struct neighbour *n;
struct net *net = dev_net(dev);
/* arp_rcv below verifies the ARP header and verifies the device
* is ARP'able.
*/
if (in_dev == NULL)
goto out;
arp = arp_hdr(skb);
switch (dev_type) {
default:
if (arp->ar_pro != htons(ETH_P_IP) ||
htons(dev_type) != arp->ar_hrd)
goto out;
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;
break;
case ARPHRD_AX25:
if (arp->ar_pro != htons(AX25_P_IP) ||
arp->ar_hrd != htons(ARPHRD_AX25))
goto out;
break;
case ARPHRD_NETROM:
if (arp->ar_pro != htons(AX25_P_IP) ||
arp->ar_hrd != htons(ARPHRD_NETROM))
goto out;
break;
}
/* Understand only these message types */
if (arp->ar_op != htons(ARPOP_REPLY) &&
arp->ar_op != htons(ARPOP_REQUEST))
goto out;
/*
* 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:
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;
/*
* 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.
*/
/* Special case: IPv4 duplicate address detection packet (RFC2131) */
if (sip == 0) {
if (arp->ar_op == htons(ARPOP_REQUEST) &&
inet_addr_type(net, tip) == RTN_LOCAL &&
!arp_ignore(in_dev, sip, tip))
arp_send(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, sha,
dev->dev_addr, sha);
goto out;
}
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(ARPOP_REPLY, ETH_P_ARP, sip,
dev, tip, sha, dev->dev_addr,
sha);
neigh_release(n);
}
}
goto out;
} 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 ||
in_dev->arp_parms->proxy_delay == 0) {
arp_send(ARPOP_REPLY, ETH_P_ARP, sip,
dev, tip, sha, dev->dev_addr,
sha);
} else {
pneigh_enqueue(&arp_tbl,
in_dev->arp_parms, skb);
return 0;
}
goto out;
}
}
}
/* Update our ARP tables */
n = __neigh_lookup(&arp_tbl, &sip, dev, 0);
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 == NULL &&
(arp->ar_op == htons(ARPOP_REPLY) ||
(arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
inet_addr_type(net, 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 + n->parms->locktime);
/* 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);
neigh_release(n);
}
out:
consume_skb(skb);
return 0;
}
static void parp_redo(struct sk_buff *skb)
{
arp_process(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;
if (dev->flags & IFF_NOARP ||
skb->pkt_type == PACKET_OTHERHOST ||
skb->pkt_type == PACKET_LOOPBACK)
goto freeskb;
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, skb, dev, NULL, arp_process);
freeskb:
kfree_skb(skb);
out_of_mem:
return 0;
}
/*
* 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 == NULL) {
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) == NULL)
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 == NULL) {
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);
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) {
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));
neigh_release(neigh);
err = 0;
}
return err;
}
int arp_invalidate(struct net_device *dev, __be32 ip)
{
struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev);
int err = -ENXIO;
if (neigh) {
if (neigh->nud_state & ~NUD_NOARP)
err = neigh_update(neigh, NULL, NUD_FAILED,
NEIGH_UPDATE_F_OVERRIDE|
NEIGH_UPDATE_F_ADMIN);
neigh_release(neigh);
}
return err;
}
EXPORT_SYMBOL(arp_invalidate);
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 == NULL) {
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;
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 == NULL)
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 = ptr;
switch (event) {
case NETDEV_CHANGEADDR:
neigh_changeaddr(&arp_tbl, dev);
rt_cache_flush(dev_net(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(&arp_tbl);
dev_add_pack(&arp_packet_type);
arp_proc_init();
#ifdef CONFIG_SYSCTL
neigh_sysctl_register(NULL, &arp_tbl.parms, "ipv4", NULL);
#endif
register_netdevice_notifier(&arp_netdev_notifier);
}
#ifdef CONFIG_PROC_FS
#if IS_ENABLED(CONFIG_AX25)
/* ------------------------------------------------------------------------ */
/*
* ax25 -> ASCII conversion
*/
static char *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 == '-')
return "*";
return buf;
}
#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%s * %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 arp_seq_open(struct inode *inode, struct file *file)
{
return seq_open_net(inode, file, &arp_seq_ops,
sizeof(struct neigh_seq_state));
}
static const struct file_operations arp_seq_fops = {
.owner = THIS_MODULE,
.open = arp_seq_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release_net,
};
static int __net_init arp_net_init(struct net *net)
{
if (!proc_create("arp", S_IRUGO, net->proc_net, &arp_seq_fops))
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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