cregit-Linux how code gets into the kernel

Release 4.8 net/ipv4/arp.c

Directory: net/ipv4
/* 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] = 64 * 1024,
			[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; }

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timo terastimo teras1715.74%110.00%
roland dreierroland dreier1211.11%110.00%
rolf manderscheidrolf manderscheid43.70%110.00%
al viroal viro10.93%110.00%
Total108100.00%10100.00%


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

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pre-gitpre-git2064.52%120.00%
david s. millerdavid s. miller825.81%360.00%
eric dumazeteric dumazet39.68%120.00%
Total31100.00%5100.00%


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

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eric w. biedermaneric w. biederman25100.00%1100.00%
Total25100.00%1100.00%


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) { 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; }

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pre-gitpre-git24080.27%1150.00%
herbert xuherbert xu3210.70%29.09%
denis v. lunevdenis v. lunev103.34%29.09%
stephen hemmingerstephen hemminger51.67%14.55%
hideaki yoshifujihideaki yoshifuji31.00%14.55%
david aherndavid ahern31.00%14.55%
al viroal viro20.67%14.55%
changli gaochangli gao20.67%14.55%
ian morrisian morris10.33%14.55%
david s. millerdavid s. miller10.33%14.55%
Total299100.00%22100.00%


static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb) { dst_link_failure(skb); kfree_skb(skb); }

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pre-gitpre-git26100.00%4100.00%
Total26100.00%4100.00%

/* 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); }

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thomas grafthomas graf9693.20%133.33%
jiri bencjiri benc76.80%266.67%
Total103100.00%3100.00%


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); }

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thomas grafthomas graf61100.00%1100.00%
Total61100.00%1100.00%

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); }

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pre-gitpre-git14040.94%833.33%
julian anastasovjulian anastasov8524.85%14.17%
jiri bencjiri benc288.19%14.17%
eric dumazeteric dumazet236.73%28.33%
changli gaochangli gao113.22%14.17%
americo wangamerico wang102.92%14.17%
jiri pirkojiri pirko102.92%14.17%
arnaldo carvalho de meloarnaldo carvalho de melo92.63%14.17%
david aherndavid ahern61.75%14.17%
hideaki yoshifujihideaki yoshifuji61.75%14.17%
david s. millerdavid s. miller41.17%14.17%
al viroal viro30.88%14.17%
eric w. biedermaneric w. biederman20.58%14.17%
denis v. lunevdenis v. lunev20.58%14.17%
thomas grafthomas graf20.58%14.17%
joe perchesjoe perches10.29%14.17%
Total342100.00%24100.00%


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); }

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julian anastasovjulian anastasov10883.72%125.00%
nicolas dichtelnicolas dichtel1813.95%125.00%
al viroal viro21.55%125.00%
denis v. lunevdenis v. lunev10.78%125.00%
Total129100.00%4100.00%


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(net, LINUX_MIB_ARPFILTER); flag = 1; } ip_rt_put(rt); return flag; }

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linus torvaldslinus torvalds5861.70%19.09%
david s. millerdavid s. miller1718.09%218.18%
pavel emelianovpavel emelianov1010.64%218.18%
hideaki yoshifujihideaki yoshifuji44.26%218.18%
denis v. lunevdenis v. lunev22.13%218.18%
al viroal viro22.13%19.09%
eric dumazeteric dumazet11.06%19.09%
Total94100.00%11100.00%

/* * 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; }

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alexey kuznetsovalexey kuznetsov9177.12%125.00%
jesper dangaard brouerjesper dangaard brouer1815.25%125.00%
eric dumazeteric dumazet54.24%125.00%
changli gaochangli gao43.39%125.00%
Total118100.00%4100.00%

/* * 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; }

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jesper dangaard brouerjesper dangaard brouer66100.00%1100.00%
Total66100.00%1100.00%

/* * 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 = (struct arphdr *) 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; }

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pre-gitpre-git36279.74%1961.29%
shmulik henshmulik hen214.63%13.23%
hideaki yoshifujihideaki yoshifuji214.63%13.23%
herbert xuherbert xu194.19%13.23%
arnaldo carvalho de meloarnaldo carvalho de melo112.42%26.45%
david s. millerdavid s. miller40.88%13.23%
pavel emelianovpavel emelianov40.88%13.23%
igor maravicigor maravic30.66%13.23%
jan engelhardtjan engelhardt30.66%13.23%
ian morrisian morris30.66%13.23%
al viroal viro20.44%13.23%
stephen hemmingerstephen hemminger10.22%13.23%
Total454100.00%31100.00%

EXPORT_SYMBOL(arp_create);
static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) { return dev_queue_xmit(skb); }

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eric w. biedermaneric w. biederman27100.00%2100.00%
Total27100.00%2100.00%

/* * 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); }

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david s. millerdavid s. miller1232.43%225.00%
shmulik henshmulik hen1232.43%112.50%
eric w. biedermaneric w. biederman821.62%225.00%
pre-gitpre-git410.81%225.00%
jan engelhardtjan engelhardt12.70%112.50%
Total37100.00%8100.00%

EXPORT_SYMBOL(arp_xmit); /* * 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; __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: 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) {