/* linux/net/ipv4/arp.c * * Version: $Id: arp.c,v 1.99 2001/08/30 22:55:42 davem Exp $ * * 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 */ #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/trdevice.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/jhash.h> #ifdef CONFIG_SYSCTL #include <linux/sysctl.h> #endif #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> #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) #include <net/ax25.h> #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE) #include <net/netrom.h> #endif #endif #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE) #include <net/atmclip.h> struct neigh_table *clip_tbl_hook; #endif #include <asm/system.h> #include <asm/uaccess.h> #include <linux/netfilter_arp.h> /* * Interface to generic neighbour cache. */ static u32 arp_hash(const void *pkey, const struct net_device *dev); 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 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, .hh_output = dev_queue_xmit, .queue_xmit = dev_queue_xmit, }; static 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, .hh_output = dev_queue_xmit, .queue_xmit = dev_queue_xmit, }; static struct neigh_ops arp_direct_ops = { .family = AF_INET, .output = dev_queue_xmit, .connected_output = dev_queue_xmit, .hh_output = dev_queue_xmit, .queue_xmit = dev_queue_xmit, }; 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, .hh_output = dev_queue_xmit, .queue_xmit = dev_queue_xmit, }; struct neigh_table arp_tbl = { .family = AF_INET, .entry_size = sizeof(struct neighbour) + 4, .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 = 3, .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, }; 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_IEEE802_TR: ip_tr_mc_map(addr, haddr); return 0; case ARPHRD_INFINIBAND: ip_ib_mc_map(addr, 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) { return jhash_2words(*(u32 *)pkey, dev->ifindex, arp_tbl.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; neigh->type = inet_addr_type(addr); rcu_read_lock(); in_dev = __in_dev_get_rcu(dev); if (in_dev == NULL) { rcu_read_unlock(); return -EINVAL; } parms = in_dev->arp_parms; __neigh_parms_put(neigh->parms); neigh->parms = neigh_parms_clone(parms); rcu_read_unlock(); if (dev->hard_header == NULL) { neigh->nud_state = NUD_NOARP; neigh->ops = &arp_direct_ops; neigh->output = neigh->ops->queue_xmit; } 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 defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) case ARPHRD_AX25: #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE) case ARPHRD_NETROM: #endif neigh->ops = &arp_broken_ops; neigh->output = neigh->ops->output; return 0; #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->hard_header_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 = NULL; struct net_device *dev = neigh->dev; __be32 target = *(__be32*)neigh->primary_key; int probes = atomic_read(&neigh->probes); struct in_device *in_dev = in_dev_get(dev); if (!in_dev) return; switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { default: case 0: /* By default announce any local IP */ if (skb && inet_addr_type(skb->nh.iph->saddr) == RTN_LOCAL) saddr = skb->nh.iph->saddr; break; case 1: /* Restrict announcements of saddr in same subnet */ if (!skb) break; saddr = skb->nh.iph->saddr; if (inet_addr_type(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; } if (in_dev) in_dev_put(in_dev); if (!saddr) saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); if ((probes -= neigh->parms->ucast_probes) < 0) { if (!(neigh->nud_state&NUD_VALID)) printk(KERN_DEBUG "trying to ucast probe in NUD_INVALID\n"); dst_ha = neigh->ha; read_lock_bh(&neigh->lock); } else if ((probes -= neigh->parms->app_probes) < 0) { #ifdef CONFIG_ARPD neigh_app_ns(neigh); #endif return; } arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, dst_ha, dev->dev_addr, NULL); if (dst_ha) read_unlock_bh(&neigh->lock); } static int arp_ignore(struct in_device *in_dev, struct net_device *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; 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(dev, sip, tip, scope); } static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = sip, .saddr = tip } } }; struct rtable *rt; int flag = 0; /*unsigned long now; */ if (ip_route_output_key(&rt, &fl) < 0) return 1; if (rt->u.dst.dev != dev) { NET_INC_STATS_BH(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: printk(KERN_DEBUG "ARP: 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) { printk(KERN_DEBUG "arp_find is called with dst==NULL\n"); kfree_skb(skb); return 1; } paddr = ((struct rtable*)skb->dst)->rt_gateway; if (arp_set_predefined(inet_addr_type(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) { read_lock_bh(&n->lock); memcpy(haddr, n->ha, dev->addr_len); read_unlock_bh(&n->lock); neigh_release(n); return 0; } neigh_release(n); } else kfree_skb(skb); return 1; } /* END OF OBSOLETE FUNCTIONS */ int arp_bind_neighbour(struct dst_entry *dst) { struct net_device *dev = dst->dev; struct neighbour *n = dst->neighbour; if (dev == NULL) return -EINVAL; if (n == NULL) { __be32 nexthop = ((struct rtable*)dst)->rt_gateway; if (dev->flags&(IFF_LOOPBACK|IFF_POINTOPOINT)) nexthop = 0; n = __neigh_lookup_errno( #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE) dev->type == ARPHRD_ATM ? clip_tbl_hook : #endif &arp_tbl, &nexthop, dev); if (IS_ERR(n)) return PTR_ERR(n); dst->neighbour = n; } return 0; } /* * Check if we can use proxy ARP for this path */ static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt) { struct in_device *out_dev; int imi, omi = -1; if (!IN_DEV_PROXY_ARP(in_dev)) return 0; if ((imi = IN_DEV_MEDIUM_ID(in_dev)) == 0) return 1; if (imi == -1) return 0; /* place to check for proxy_arp for routes */ if ((out_dev = in_dev_get(rt->u.dst.dev)) != NULL) { omi = IN_DEV_MEDIUM_ID(out_dev); in_dev_put(out_dev); } return (omi != imi && omi != -1); } /* * 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, unsigned char *dest_hw, unsigned char *src_hw, unsigned char *target_hw) { struct sk_buff *skb; struct arphdr *arp; unsigned char *arp_ptr; /* * Allocate a buffer */ skb = alloc_skb(sizeof(struct arphdr)+ 2*(dev->addr_len+4) + LL_RESERVED_SPACE(dev), GFP_ATOMIC); if (skb == NULL) return NULL; skb_reserve(skb, LL_RESERVED_SPACE(dev)); skb->nh.raw = skb->data; arp = (struct arphdr *) skb_put(skb,sizeof(struct arphdr) + 2*(dev->addr_len+4)); 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 && 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 defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) case ARPHRD_AX25: arp->ar_hrd = htons(ARPHRD_AX25); arp->ar_pro = htons(AX25_P_IP); break; #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE) case ARPHRD_NETROM: arp->ar_hrd = htons(ARPHRD_NETROM); arp->ar_pro = htons(AX25_P_IP); break; #endif #endif #ifdef CONFIG_FDDI case ARPHRD_FDDI: arp->ar_hrd = htons(ARPHRD_ETHER); arp->ar_pro = htons(ETH_P_IP); break; #endif #ifdef CONFIG_TR case ARPHRD_IEEE802_TR: arp->ar_hrd = htons(ARPHRD_IEEE802); 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; 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; } /* * Send an arp packet. */ void arp_xmit(struct sk_buff *skb) { /* Send it off, maybe filter it using firewalling first. */ NF_HOOK(NF_ARP, NF_ARP_OUT, skb, NULL, skb->dev, dev_queue_xmit); } /* * Create and send an arp packet. */ void arp_send(int type, int ptype, __be32 dest_ip, struct net_device *dev, __be32 src_ip, unsigned char *dest_hw, unsigned char *src_hw, 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); } /* * 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(dev); struct arphdr *arp; unsigned char *arp_ptr; struct rtable *rt; unsigned char *sha, *tha; __be32 sip, tip; u16 dev_type = dev->type; int addr_type; struct neighbour *n; /* arp_rcv below verifies the ARP header and verifies the device * is ARP'able. */ if (in_dev == NULL) goto out; arp = skb->nh.arph; switch (dev_type) { default: if (arp->ar_pro != htons(ETH_P_IP) || htons(dev_type) != arp->ar_hrd) goto out; break; #ifdef CONFIG_NET_ETHERNET case ARPHRD_ETHER: #endif #ifdef CONFIG_TR case ARPHRD_IEEE802_TR: #endif #ifdef CONFIG_FDDI case ARPHRD_FDDI: #endif #ifdef CONFIG_NET_FC case ARPHRD_IEEE802: #endif #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_TR) || \ defined(CONFIG_FDDI) || defined(CONFIG_NET_FC) /* * ETHERNET, Token Ring 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; #endif #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) case ARPHRD_AX25: if (arp->ar_pro != htons(AX25_P_IP) || arp->ar_hrd != htons(ARPHRD_AX25)) goto out; break; #if defined(CONFIG_NETROM) || defined(CONFIG_NETROM_MODULE) case ARPHRD_NETROM: if (arp->ar_pro != htons(AX25_P_IP) || arp->ar_hrd != htons(ARPHRD_NETROM)) goto out; break; #endif #endif } /* 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; 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 (LOOPBACK(tip) || MULTICAST(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(tip) == RTN_LOCAL && !arp_ignore(in_dev,dev,sip,tip)) arp_send(ARPOP_REPLY,ETH_P_ARP,tip,dev,tip,sha,dev->dev_addr,dev->dev_addr); goto out; } if (arp->ar_op == htons(ARPOP_REQUEST) && ip_route_input(skb, tip, sip, 0, dev) == 0) { rt = (struct rtable*)skb->dst; addr_type = rt->rt_type; if (addr_type == RTN_LOCAL) { n = neigh_event_ns(&arp_tbl, sha, &sip, dev); if (n) { int dont_send = 0; if (!dont_send) dont_send |= arp_ignore(in_dev,dev,sip,tip); if (!dont_send && IN_DEV_ARPFILTER(in_dev)) dont_send |= arp_filter(sip,tip,dev); if (!dont_send) 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 ((rt->rt_flags&RTCF_DNAT) || (addr_type == RTN_UNICAST && rt->u.dst.dev != dev && (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, &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); in_dev_put(in_dev); return 0; } goto out; } } } /* Update our ARP tables */ n = __neigh_lookup(&arp_tbl, &sip, dev, 0); if (ipv4_devconf.arp_accept) { /* 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) && inet_addr_type(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: if (in_dev) in_dev_put(in_dev); kfree_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) { struct arphdr *arp; /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ if (!pskb_may_pull(skb, (sizeof(struct arphdr) + (2 * dev->addr_len) + (2 * sizeof(u32))))) goto freeskb; arp = skb->nh.arph; if (arp->ar_hln != dev->addr_len || dev->flags & IFF_NOARP || skb->pkt_type == PACKET_OTHERHOST || skb->pkt_type == PACKET_LOOPBACK || arp->ar_pln != 4) goto freeskb; if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) goto out_of_mem; memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); return NF_HOOK(NF_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(struct arpreq *r, struct net_device * dev) { __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; struct neighbour *neigh; int err; if (r->arp_flags&ATF_PUBL) { __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(r->arp_ha.sa_family, r->arp_ha.sa_data); if (!dev) return -ENODEV; } if (mask) { if (pneigh_lookup(&arp_tbl, &ip, dev, 1) == NULL) return -ENOBUFS; return 0; } if (dev == NULL) { ipv4_devconf.proxy_arp = 1; return 0; } if (__in_dev_get_rtnl(dev)) { __in_dev_get_rtnl(dev)->cnf.proxy_arp = 1; return 0; } return -ENXIO; } if (r->arp_flags & ATF_PERM) r->arp_flags |= ATF_COM; if (dev == NULL) { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip, .tos = RTO_ONLINK } } }; struct rtable * rt; if ((err = ip_route_output_key(&rt, &fl)) != 0) return err; dev = rt->u.dst.dev; ip_rt_put(rt); if (!dev) return -EINVAL; } switch (dev->type) { #ifdef 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 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 arp_state_to_flags(struct neighbour *neigh) { unsigned flags = 0; if (neigh->nud_state&NUD_PERMANENT) flags = ATF_PERM|ATF_COM; else if (neigh->nud_state&NUD_VALID) flags = ATF_COM; return flags; } /* * 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; } static int arp_req_delete(struct arpreq *r, struct net_device * dev) { int err; __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; struct neighbour *neigh; if (r->arp_flags & ATF_PUBL) { __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; if (mask == htonl(0xFFFFFFFF)) return pneigh_delete(&arp_tbl, &ip, dev); if (mask == 0) { if (dev == NULL) { ipv4_devconf.proxy_arp = 0; return 0; } if (__in_dev_get_rtnl(dev)) { __in_dev_get_rtnl(dev)->cnf.proxy_arp = 0; return 0; } return -ENXIO; } return -EINVAL; } if (dev == NULL) { struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip, .tos = RTO_ONLINK } } }; struct rtable * rt; if ((err = ip_route_output_key(&rt, &fl)) != 0) return err; dev = rt->u.dst.dev; ip_rt_put(rt); if (!dev) return -EINVAL; } err = -ENXIO; neigh = neigh_lookup(&arp_tbl, &ip, dev); 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; } /* * Handle an ARP layer I/O control request. */ int arp_ioctl(unsigned int cmd, void __user *arg) { int err; struct arpreq r; struct net_device *dev = NULL; switch (cmd) { case SIOCDARP: case SIOCSARP: if (!capable(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; if ((dev = __dev_get_by_name(r.arp_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(&r, dev); break; case SIOCSARP: err = arp_req_set(&r, dev); break; case SIOCGARP: err = arp_req_get(&r, dev); if (!err && copy_to_user(arg, &r, sizeof(r))) err = -EFAULT; break; } out: rtnl_unlock(); 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(0); 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 = { .type = __constant_htons(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, NET_IPV4, NET_IPV4_NEIGH, "ipv4", NULL, NULL); #endif register_netdevice_notifier(&arp_netdev_notifier); } #ifdef CONFIG_PROC_FS #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) /* ------------------------------------------------------------------------ */ /* * 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++ = '-'; if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 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]; const char hexbuf[] = "0123456789ABCDEF"; 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 defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) 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++] = hexbuf[(n->ha[j] >> 4) & 15]; hbuffer[k++] = hexbuf[n->ha[j] & 15]; hbuffer[k++] = ':'; } hbuffer[--k] = 0; #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE) } #endif sprintf(tbuf, "%u.%u.%u.%u", NIPQUAD(*(u32*)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, "%u.%u.%u.%u", NIPQUAD(*(u32*)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 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) { struct seq_file *seq; int rc = -ENOMEM; struct neigh_seq_state *s = kzalloc(sizeof(*s), GFP_KERNEL); if (!s) goto out; rc = seq_open(file, &arp_seq_ops); if (rc) goto out_kfree; seq = file->private_data; seq->private = s; out: return rc; out_kfree: kfree(s); goto out; } static const struct file_operations arp_seq_fops = { .owner = THIS_MODULE, .open = arp_seq_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release_private, }; static int __init arp_proc_init(void) { if (!proc_net_fops_create("arp", S_IRUGO, &arp_seq_fops)) return -ENOMEM; return 0; } #else /* CONFIG_PROC_FS */ static int __init arp_proc_init(void) { return 0; } #endif /* CONFIG_PROC_FS */ EXPORT_SYMBOL(arp_broken_ops); EXPORT_SYMBOL(arp_find); EXPORT_SYMBOL(arp_create); EXPORT_SYMBOL(arp_xmit); EXPORT_SYMBOL(arp_send); EXPORT_SYMBOL(arp_tbl); #if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE) EXPORT_SYMBOL(clip_tbl_hook); #endif