diff options
Diffstat (limited to 'net/ipv4/arp.c')
| -rw-r--r-- | net/ipv4/arp.c | 1472 |
1 files changed, 1472 insertions, 0 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c new file mode 100644 index 0000000000..9456f5bb35 --- /dev/null +++ b/net/ipv4/arp.c @@ -0,0 +1,1472 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* linux/net/ipv4/arp.c + * + * Copyright (C) 1994 by Florian La Roche + * + * This module implements the Address Resolution Protocol ARP (RFC 826), + * which is used to convert IP addresses (or in the future maybe other + * high-level addresses) into a low-level hardware address (like an Ethernet + * address). + * + * Fixes: + * Alan Cox : Removed the Ethernet assumptions in + * Florian's code + * Alan Cox : Fixed some small errors in the ARP + * logic + * Alan Cox : Allow >4K in /proc + * Alan Cox : Make ARP add its own protocol entry + * Ross Martin : Rewrote arp_rcv() and arp_get_info() + * Stephen Henson : Add AX25 support to arp_get_info() + * Alan Cox : Drop data when a device is downed. + * Alan Cox : Use init_timer(). + * Alan Cox : Double lock fixes. + * Martin Seine : Move the arphdr structure + * to if_arp.h for compatibility. + * with BSD based programs. + * Andrew Tridgell : Added ARP netmask code and + * re-arranged proxy handling. + * Alan Cox : Changed to use notifiers. + * Niibe Yutaka : Reply for this device or proxies only. + * Alan Cox : Don't proxy across hardware types! + * Jonathan Naylor : Added support for NET/ROM. + * Mike Shaver : RFC1122 checks. + * Jonathan Naylor : Only lookup the hardware address for + * the correct hardware type. + * Germano Caronni : Assorted subtle races. + * Craig Schlenter : Don't modify permanent entry + * during arp_rcv. + * Russ Nelson : Tidied up a few bits. + * Alexey Kuznetsov: Major changes to caching and behaviour, + * eg intelligent arp probing and + * generation + * of host down events. + * Alan Cox : Missing unlock in device events. + * Eckes : ARP ioctl control errors. + * Alexey Kuznetsov: Arp free fix. + * Manuel Rodriguez: Gratuitous ARP. + * Jonathan Layes : Added arpd support through kerneld + * message queue (960314) + * Mike Shaver : /proc/sys/net/ipv4/arp_* support + * Mike McLagan : Routing by source + * Stuart Cheshire : Metricom and grat arp fixes + * *** FOR 2.1 clean this up *** + * Lawrence V. Stefani: (08/12/96) Added FDDI support. + * Alan Cox : Took the AP1000 nasty FDDI hack and + * folded into the mainstream FDDI code. + * Ack spit, Linus how did you allow that + * one in... + * Jes Sorensen : Make FDDI work again in 2.1.x and + * clean up the APFDDI & gen. FDDI bits. + * Alexey Kuznetsov: new arp state machine; + * now it is in net/core/neighbour.c. + * Krzysztof Halasa: Added Frame Relay ARP support. + * Arnaldo C. Melo : convert /proc/net/arp to seq_file + * Shmulik Hen: Split arp_send to arp_create and + * arp_xmit so intermediate drivers like + * bonding can change the skb before + * sending (e.g. insert 8021q tag). + * Harald Welte : convert to make use of jenkins hash + * Jesper D. Brouer: Proxy ARP PVLAN RFC 3069 support. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/string.h> +#include <linux/kernel.h> +#include <linux/capability.h> +#include <linux/socket.h> +#include <linux/sockios.h> +#include <linux/errno.h> +#include <linux/in.h> +#include <linux/mm.h> +#include <linux/inet.h> +#include <linux/inetdevice.h> +#include <linux/netdevice.h> +#include <linux/etherdevice.h> +#include <linux/fddidevice.h> +#include <linux/if_arp.h> +#include <linux/skbuff.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/stat.h> +#include <linux/init.h> +#include <linux/net.h> +#include <linux/rcupdate.h> +#include <linux/slab.h> +#ifdef CONFIG_SYSCTL +#include <linux/sysctl.h> +#endif + +#include <net/net_namespace.h> +#include <net/ip.h> +#include <net/icmp.h> +#include <net/route.h> +#include <net/protocol.h> +#include <net/tcp.h> +#include <net/sock.h> +#include <net/arp.h> +#include <net/ax25.h> +#include <net/netrom.h> +#include <net/dst_metadata.h> +#include <net/ip_tunnels.h> + +#include <linux/uaccess.h> + +#include <linux/netfilter_arp.h> + +/* + * Interface to generic neighbour cache. + */ +static u32 arp_hash(const void *pkey, const struct net_device *dev, __u32 *hash_rnd); +static bool arp_key_eq(const struct neighbour *n, const void *pkey); +static int arp_constructor(struct neighbour *neigh); +static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); +static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); +static void parp_redo(struct sk_buff *skb); +static int arp_is_multicast(const void *pkey); + +static const struct neigh_ops arp_generic_ops = { + .family = AF_INET, + .solicit = arp_solicit, + .error_report = arp_error_report, + .output = neigh_resolve_output, + .connected_output = neigh_connected_output, +}; + +static const struct neigh_ops arp_hh_ops = { + .family = AF_INET, + .solicit = arp_solicit, + .error_report = arp_error_report, + .output = neigh_resolve_output, + .connected_output = neigh_resolve_output, +}; + +static const struct neigh_ops arp_direct_ops = { + .family = AF_INET, + .output = neigh_direct_output, + .connected_output = neigh_direct_output, +}; + +struct neigh_table arp_tbl = { + .family = AF_INET, + .key_len = 4, + .protocol = cpu_to_be16(ETH_P_IP), + .hash = arp_hash, + .key_eq = arp_key_eq, + .constructor = arp_constructor, + .proxy_redo = parp_redo, + .is_multicast = arp_is_multicast, + .id = "arp_cache", + .parms = { + .tbl = &arp_tbl, + .reachable_time = 30 * HZ, + .data = { + [NEIGH_VAR_MCAST_PROBES] = 3, + [NEIGH_VAR_UCAST_PROBES] = 3, + [NEIGH_VAR_RETRANS_TIME] = 1 * HZ, + [NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ, + [NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ, + [NEIGH_VAR_INTERVAL_PROBE_TIME_MS] = 5 * HZ, + [NEIGH_VAR_GC_STALETIME] = 60 * HZ, + [NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX, + [NEIGH_VAR_PROXY_QLEN] = 64, + [NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ, + [NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10, + [NEIGH_VAR_LOCKTIME] = 1 * HZ, + }, + }, + .gc_interval = 30 * HZ, + .gc_thresh1 = 128, + .gc_thresh2 = 512, + .gc_thresh3 = 1024, +}; +EXPORT_SYMBOL(arp_tbl); + +int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir) +{ + switch (dev->type) { + case ARPHRD_ETHER: + case ARPHRD_FDDI: + case ARPHRD_IEEE802: + ip_eth_mc_map(addr, haddr); + return 0; + case ARPHRD_INFINIBAND: + ip_ib_mc_map(addr, dev->broadcast, haddr); + return 0; + case ARPHRD_IPGRE: + ip_ipgre_mc_map(addr, dev->broadcast, haddr); + return 0; + default: + if (dir) { + memcpy(haddr, dev->broadcast, dev->addr_len); + return 0; + } + } + return -EINVAL; +} + + +static u32 arp_hash(const void *pkey, + const struct net_device *dev, + __u32 *hash_rnd) +{ + return arp_hashfn(pkey, dev, hash_rnd); +} + +static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) +{ + return neigh_key_eq32(neigh, pkey); +} + +static int arp_constructor(struct neighbour *neigh) +{ + __be32 addr; + struct net_device *dev = neigh->dev; + struct in_device *in_dev; + struct neigh_parms *parms; + u32 inaddr_any = INADDR_ANY; + + if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) + memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len); + + addr = *(__be32 *)neigh->primary_key; + rcu_read_lock(); + in_dev = __in_dev_get_rcu(dev); + if (!in_dev) { + rcu_read_unlock(); + return -EINVAL; + } + + neigh->type = inet_addr_type_dev_table(dev_net(dev), dev, addr); + + parms = in_dev->arp_parms; + __neigh_parms_put(neigh->parms); + neigh->parms = neigh_parms_clone(parms); + rcu_read_unlock(); + + if (!dev->header_ops) { + neigh->nud_state = NUD_NOARP; + neigh->ops = &arp_direct_ops; + neigh->output = neigh_direct_output; + } else { + /* Good devices (checked by reading texts, but only Ethernet is + tested) + + ARPHRD_ETHER: (ethernet, apfddi) + ARPHRD_FDDI: (fddi) + ARPHRD_IEEE802: (tr) + ARPHRD_METRICOM: (strip) + ARPHRD_ARCNET: + etc. etc. etc. + + ARPHRD_IPDDP will also work, if author repairs it. + I did not it, because this driver does not work even + in old paradigm. + */ + + if (neigh->type == RTN_MULTICAST) { + neigh->nud_state = NUD_NOARP; + arp_mc_map(addr, neigh->ha, dev, 1); + } else if (dev->flags & (IFF_NOARP | IFF_LOOPBACK)) { + neigh->nud_state = NUD_NOARP; + memcpy(neigh->ha, dev->dev_addr, 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_reason(skb, SKB_DROP_REASON_NEIGH_FAILED); +} + +/* Create and send an arp packet. */ +static void arp_send_dst(int type, int ptype, __be32 dest_ip, + struct net_device *dev, __be32 src_ip, + const unsigned char *dest_hw, + const unsigned char *src_hw, + const unsigned char *target_hw, + struct dst_entry *dst) +{ + struct sk_buff *skb; + + /* arp on this interface. */ + if (dev->flags & IFF_NOARP) + return; + + skb = arp_create(type, ptype, dest_ip, dev, src_ip, + dest_hw, src_hw, target_hw); + if (!skb) + return; + + skb_dst_set(skb, dst_clone(dst)); + arp_xmit(skb); +} + +void arp_send(int type, int ptype, __be32 dest_ip, + struct net_device *dev, __be32 src_ip, + const unsigned char *dest_hw, const unsigned char *src_hw, + const unsigned char *target_hw) +{ + arp_send_dst(type, ptype, dest_ip, dev, src_ip, dest_hw, src_hw, + target_hw, NULL); +} +EXPORT_SYMBOL(arp_send); + +static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb) +{ + __be32 saddr = 0; + u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL; + struct net_device *dev = neigh->dev; + __be32 target = *(__be32 *)neigh->primary_key; + int probes = atomic_read(&neigh->probes); + struct in_device *in_dev; + struct dst_entry *dst = NULL; + + rcu_read_lock(); + in_dev = __in_dev_get_rcu(dev); + if (!in_dev) { + rcu_read_unlock(); + return; + } + switch (IN_DEV_ARP_ANNOUNCE(in_dev)) { + default: + case 0: /* By default announce any local IP */ + if (skb && inet_addr_type_dev_table(dev_net(dev), dev, + ip_hdr(skb)->saddr) == RTN_LOCAL) + saddr = ip_hdr(skb)->saddr; + break; + case 1: /* Restrict announcements of saddr in same subnet */ + if (!skb) + break; + saddr = ip_hdr(skb)->saddr; + if (inet_addr_type_dev_table(dev_net(dev), dev, + saddr) == RTN_LOCAL) { + /* saddr should be known to target */ + if (inet_addr_onlink(in_dev, target, saddr)) + break; + } + saddr = 0; + break; + case 2: /* Avoid secondary IPs, get a primary/preferred one */ + break; + } + rcu_read_unlock(); + + if (!saddr) + saddr = inet_select_addr(dev, target, RT_SCOPE_LINK); + + probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES); + if (probes < 0) { + if (!(READ_ONCE(neigh->nud_state) & NUD_VALID)) + pr_debug("trying to ucast probe in NUD_INVALID\n"); + neigh_ha_snapshot(dst_ha, neigh, dev); + dst_hw = dst_ha; + } else { + probes -= NEIGH_VAR(neigh->parms, APP_PROBES); + if (probes < 0) { + neigh_app_ns(neigh); + return; + } + } + + if (skb && !(dev->priv_flags & IFF_XMIT_DST_RELEASE)) + dst = skb_dst(skb); + arp_send_dst(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr, + dst_hw, dev->dev_addr, NULL, dst); +} + +static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) +{ + struct net *net = dev_net(in_dev->dev); + int scope; + + switch (IN_DEV_ARP_IGNORE(in_dev)) { + case 0: /* Reply, the tip is already validated */ + return 0; + case 1: /* Reply only if tip is configured on the incoming interface */ + sip = 0; + scope = RT_SCOPE_HOST; + break; + case 2: /* + * Reply only if tip is configured on the incoming interface + * and is in same subnet as sip + */ + scope = RT_SCOPE_HOST; + break; + case 3: /* Do not reply for scope host addresses */ + sip = 0; + scope = RT_SCOPE_LINK; + in_dev = NULL; + break; + case 4: /* Reserved */ + case 5: + case 6: + case 7: + return 0; + case 8: /* Do not reply */ + return 1; + default: + return 0; + } + return !inet_confirm_addr(net, in_dev, sip, tip, scope); +} + +static int arp_accept(struct in_device *in_dev, __be32 sip) +{ + struct net *net = dev_net(in_dev->dev); + int scope = RT_SCOPE_LINK; + + switch (IN_DEV_ARP_ACCEPT(in_dev)) { + case 0: /* Don't create new entries from garp */ + return 0; + case 1: /* Create new entries from garp */ + return 1; + case 2: /* Create a neighbor in the arp table only if sip + * is in the same subnet as an address configured + * on the interface that received the garp message + */ + return !!inet_confirm_addr(net, in_dev, sip, 0, scope); + default: + return 0; + } +} + +static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) +{ + struct rtable *rt; + int flag = 0; + /*unsigned long now; */ + struct net *net = dev_net(dev); + + rt = ip_route_output(net, sip, tip, 0, l3mdev_master_ifindex_rcu(dev)); + if (IS_ERR(rt)) + return 1; + if (rt->dst.dev != dev) { + __NET_INC_STATS(net, LINUX_MIB_ARPFILTER); + flag = 1; + } + ip_rt_put(rt); + return flag; +} + +/* + * Check if we can use proxy ARP for this path + */ +static inline int arp_fwd_proxy(struct in_device *in_dev, + struct net_device *dev, struct rtable *rt) +{ + struct in_device *out_dev; + int imi, omi = -1; + + if (rt->dst.dev == dev) + return 0; + + if (!IN_DEV_PROXY_ARP(in_dev)) + return 0; + imi = IN_DEV_MEDIUM_ID(in_dev); + if (imi == 0) + return 1; + if (imi == -1) + return 0; + + /* place to check for proxy_arp for routes */ + + out_dev = __in_dev_get_rcu(rt->dst.dev); + if (out_dev) + omi = IN_DEV_MEDIUM_ID(out_dev); + + return omi != imi && omi != -1; +} + +/* + * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev) + * + * RFC3069 supports proxy arp replies back to the same interface. This + * is done to support (ethernet) switch features, like RFC 3069, where + * the individual ports are not allowed to communicate with each + * other, BUT they are allowed to talk to the upstream router. As + * described in RFC 3069, it is possible to allow these hosts to + * communicate through the upstream router, by proxy_arp'ing. + * + * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation" + * + * This technology is known by different names: + * In RFC 3069 it is called VLAN Aggregation. + * Cisco and Allied Telesyn call it Private VLAN. + * Hewlett-Packard call it Source-Port filtering or port-isolation. + * Ericsson call it MAC-Forced Forwarding (RFC Draft). + * + */ +static inline int arp_fwd_pvlan(struct in_device *in_dev, + struct net_device *dev, struct rtable *rt, + __be32 sip, __be32 tip) +{ + /* Private VLAN is only concerned about the same ethernet segment */ + if (rt->dst.dev != dev) + return 0; + + /* Don't reply on self probes (often done by windowz boxes)*/ + if (sip == tip) + return 0; + + if (IN_DEV_PROXY_ARP_PVLAN(in_dev)) + return 1; + else + return 0; +} + +/* + * Interface to link layer: send routine and receive handler. + */ + +/* + * Create an arp packet. If dest_hw is not set, we create a broadcast + * message. + */ +struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip, + struct net_device *dev, __be32 src_ip, + const unsigned char *dest_hw, + const unsigned char *src_hw, + const unsigned char *target_hw) +{ + struct sk_buff *skb; + struct arphdr *arp; + unsigned char *arp_ptr; + int hlen = LL_RESERVED_SPACE(dev); + int tlen = dev->needed_tailroom; + + /* + * Allocate a buffer + */ + + skb = alloc_skb(arp_hdr_len(dev) + hlen + tlen, GFP_ATOMIC); + if (!skb) + return NULL; + + skb_reserve(skb, hlen); + skb_reset_network_header(skb); + arp = skb_put(skb, arp_hdr_len(dev)); + skb->dev = dev; + skb->protocol = htons(ETH_P_ARP); + if (!src_hw) + src_hw = dev->dev_addr; + if (!dest_hw) + dest_hw = dev->broadcast; + + /* + * Fill the device header for the ARP frame + */ + if (dev_hard_header(skb, dev, ptype, dest_hw, src_hw, skb->len) < 0) + goto out; + + /* + * Fill out the arp protocol part. + * + * The arp hardware type should match the device type, except for FDDI, + * which (according to RFC 1390) should always equal 1 (Ethernet). + */ + /* + * Exceptions everywhere. AX.25 uses the AX.25 PID value not the + * DIX code for the protocol. Make these device structure fields. + */ + switch (dev->type) { + default: + arp->ar_hrd = htons(dev->type); + arp->ar_pro = htons(ETH_P_IP); + break; + +#if IS_ENABLED(CONFIG_AX25) + case ARPHRD_AX25: + arp->ar_hrd = htons(ARPHRD_AX25); + arp->ar_pro = htons(AX25_P_IP); + break; + +#if IS_ENABLED(CONFIG_NETROM) + case ARPHRD_NETROM: + arp->ar_hrd = htons(ARPHRD_NETROM); + arp->ar_pro = htons(AX25_P_IP); + break; +#endif +#endif + +#if IS_ENABLED(CONFIG_FDDI) + case ARPHRD_FDDI: + arp->ar_hrd = htons(ARPHRD_ETHER); + arp->ar_pro = htons(ETH_P_IP); + break; +#endif + } + + arp->ar_hln = dev->addr_len; + arp->ar_pln = 4; + arp->ar_op = htons(type); + + arp_ptr = (unsigned char *)(arp + 1); + + memcpy(arp_ptr, src_hw, dev->addr_len); + arp_ptr += dev->addr_len; + memcpy(arp_ptr, &src_ip, 4); + arp_ptr += 4; + + switch (dev->type) { +#if IS_ENABLED(CONFIG_FIREWIRE_NET) + case ARPHRD_IEEE1394: + break; +#endif + default: + if (target_hw) + memcpy(arp_ptr, target_hw, dev->addr_len); + else + memset(arp_ptr, 0, dev->addr_len); + arp_ptr += dev->addr_len; + } + memcpy(arp_ptr, &dest_ip, 4); + + return skb; + +out: + kfree_skb(skb); + return NULL; +} +EXPORT_SYMBOL(arp_create); + +static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb) +{ + return dev_queue_xmit(skb); +} + +/* + * Send an arp packet. + */ +void arp_xmit(struct sk_buff *skb) +{ + /* Send it off, maybe filter it using firewalling first. */ + NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, + dev_net(skb->dev), NULL, skb, NULL, skb->dev, + arp_xmit_finish); +} +EXPORT_SYMBOL(arp_xmit); + +static bool arp_is_garp(struct net *net, struct net_device *dev, + int *addr_type, __be16 ar_op, + __be32 sip, __be32 tip, + unsigned char *sha, unsigned char *tha) +{ + bool is_garp = tip == sip; + + /* Gratuitous ARP _replies_ also require target hwaddr to be + * the same as source. + */ + if (is_garp && ar_op == htons(ARPOP_REPLY)) + is_garp = + /* IPv4 over IEEE 1394 doesn't provide target + * hardware address field in its ARP payload. + */ + tha && + !memcmp(tha, sha, dev->addr_len); + + if (is_garp) { + *addr_type = inet_addr_type_dev_table(net, dev, sip); + if (*addr_type != RTN_UNICAST) + is_garp = false; + } + return is_garp; +} + +/* + * Process an arp request. + */ + +static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) +{ + struct net_device *dev = skb->dev; + struct in_device *in_dev = __in_dev_get_rcu(dev); + struct arphdr *arp; + unsigned char *arp_ptr; + struct rtable *rt; + unsigned char *sha; + unsigned char *tha = NULL; + __be32 sip, tip; + u16 dev_type = dev->type; + int addr_type; + struct neighbour *n; + struct dst_entry *reply_dst = NULL; + bool is_garp = false; + + /* arp_rcv below verifies the ARP header and verifies the device + * is ARP'able. + */ + + if (!in_dev) + goto out_free_skb; + + arp = arp_hdr(skb); + + switch (dev_type) { + default: + if (arp->ar_pro != htons(ETH_P_IP) || + htons(dev_type) != arp->ar_hrd) + goto out_free_skb; + break; + case ARPHRD_ETHER: + case ARPHRD_FDDI: + case ARPHRD_IEEE802: + /* + * ETHERNET, and Fibre Channel (which are IEEE 802 + * devices, according to RFC 2625) devices will accept ARP + * hardware types of either 1 (Ethernet) or 6 (IEEE 802.2). + * This is the case also of FDDI, where the RFC 1390 says that + * FDDI devices should accept ARP hardware of (1) Ethernet, + * however, to be more robust, we'll accept both 1 (Ethernet) + * or 6 (IEEE 802.2) + */ + if ((arp->ar_hrd != htons(ARPHRD_ETHER) && + arp->ar_hrd != htons(ARPHRD_IEEE802)) || + arp->ar_pro != htons(ETH_P_IP)) + goto out_free_skb; + break; + case ARPHRD_AX25: + if (arp->ar_pro != htons(AX25_P_IP) || + arp->ar_hrd != htons(ARPHRD_AX25)) + goto out_free_skb; + break; + case ARPHRD_NETROM: + if (arp->ar_pro != htons(AX25_P_IP) || + arp->ar_hrd != htons(ARPHRD_NETROM)) + goto out_free_skb; + break; + } + + /* Understand only these message types */ + + if (arp->ar_op != htons(ARPOP_REPLY) && + arp->ar_op != htons(ARPOP_REQUEST)) + goto out_free_skb; + +/* + * Extract fields + */ + arp_ptr = (unsigned char *)(arp + 1); + sha = arp_ptr; + arp_ptr += dev->addr_len; + memcpy(&sip, arp_ptr, 4); + arp_ptr += 4; + switch (dev_type) { +#if IS_ENABLED(CONFIG_FIREWIRE_NET) + case ARPHRD_IEEE1394: + break; +#endif + default: + tha = arp_ptr; + arp_ptr += dev->addr_len; + } + memcpy(&tip, arp_ptr, 4); +/* + * Check for bad requests for 127.x.x.x and requests for multicast + * addresses. If this is one such, delete it. + */ + if (ipv4_is_multicast(tip) || + (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip))) + goto out_free_skb; + + /* + * For some 802.11 wireless deployments (and possibly other networks), + * there will be an ARP proxy and gratuitous ARP frames are attacks + * and thus should not be accepted. + */ + if (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP)) + goto out_free_skb; + +/* + * Special case: We must set Frame Relay source Q.922 address + */ + if (dev_type == ARPHRD_DLCI) + sha = dev->broadcast; + +/* + * Process entry. The idea here is we want to send a reply if it is a + * request for us or if it is a request for someone else that we hold + * a proxy for. We want to add an entry to our cache if it is a reply + * to us or if it is a request for our address. + * (The assumption for this last is that if someone is requesting our + * address, they are probably intending to talk to us, so it saves time + * if we cache their address. Their address is also probably not in + * our cache, since ours is not in their cache.) + * + * Putting this another way, we only care about replies if they are to + * us, in which case we add them to the cache. For requests, we care + * about those for us and those for our proxies. We reply to both, + * and in the case of requests for us we add the requester to the arp + * cache. + */ + + if (arp->ar_op == htons(ARPOP_REQUEST) && skb_metadata_dst(skb)) + reply_dst = (struct dst_entry *) + iptunnel_metadata_reply(skb_metadata_dst(skb), + GFP_ATOMIC); + + /* Special case: IPv4 duplicate address detection packet (RFC2131) */ + if (sip == 0) { + if (arp->ar_op == htons(ARPOP_REQUEST) && + inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL && + !arp_ignore(in_dev, sip, tip)) + arp_send_dst(ARPOP_REPLY, ETH_P_ARP, sip, dev, tip, + sha, dev->dev_addr, sha, reply_dst); + goto out_consume_skb; + } + + if (arp->ar_op == htons(ARPOP_REQUEST) && + ip_route_input_noref(skb, tip, sip, 0, dev) == 0) { + + rt = skb_rtable(skb); + addr_type = rt->rt_type; + + if (addr_type == RTN_LOCAL) { + int dont_send; + + dont_send = arp_ignore(in_dev, sip, tip); + if (!dont_send && IN_DEV_ARPFILTER(in_dev)) + dont_send = arp_filter(sip, tip, dev); + if (!dont_send) { + n = neigh_event_ns(&arp_tbl, sha, &sip, dev); + if (n) { + arp_send_dst(ARPOP_REPLY, ETH_P_ARP, + sip, dev, tip, sha, + dev->dev_addr, sha, + reply_dst); + neigh_release(n); + } + } + goto out_consume_skb; + } else if (IN_DEV_FORWARD(in_dev)) { + if (addr_type == RTN_UNICAST && + (arp_fwd_proxy(in_dev, dev, rt) || + arp_fwd_pvlan(in_dev, dev, rt, sip, tip) || + (rt->dst.dev != dev && + pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))) { + n = neigh_event_ns(&arp_tbl, sha, &sip, dev); + if (n) + neigh_release(n); + + if (NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED || + skb->pkt_type == PACKET_HOST || + NEIGH_VAR(in_dev->arp_parms, PROXY_DELAY) == 0) { + arp_send_dst(ARPOP_REPLY, ETH_P_ARP, + sip, dev, tip, sha, + dev->dev_addr, sha, + reply_dst); + } else { + pneigh_enqueue(&arp_tbl, + in_dev->arp_parms, skb); + goto out_free_dst; + } + goto out_consume_skb; + } + } + } + + /* Update our ARP tables */ + + n = __neigh_lookup(&arp_tbl, &sip, dev, 0); + + addr_type = -1; + if (n || arp_accept(in_dev, sip)) { + is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, + sip, tip, sha, tha); + } + + if (arp_accept(in_dev, sip)) { + /* Unsolicited ARP is not accepted by default. + It is possible, that this option should be enabled for some + devices (strip is candidate) + */ + if (!n && + (is_garp || + (arp->ar_op == htons(ARPOP_REPLY) && + (addr_type == RTN_UNICAST || + (addr_type < 0 && + /* postpone calculation to as late as possible */ + inet_addr_type_dev_table(net, dev, sip) == + RTN_UNICAST))))) + n = __neigh_lookup(&arp_tbl, &sip, dev, 1); + } + + if (n) { + int state = NUD_REACHABLE; + int override; + + /* If several different ARP replies follows back-to-back, + use the FIRST one. It is possible, if several proxy + agents are active. Taking the first reply prevents + arp trashing and chooses the fastest router. + */ + override = time_after(jiffies, + n->updated + + NEIGH_VAR(n->parms, LOCKTIME)) || + is_garp; + + /* Broadcast replies and request packets + do not assert neighbour reachability. + */ + if (arp->ar_op != htons(ARPOP_REPLY) || + skb->pkt_type != PACKET_HOST) + state = NUD_STALE; + neigh_update(n, sha, state, + override ? NEIGH_UPDATE_F_OVERRIDE : 0, 0); + neigh_release(n); + } + +out_consume_skb: + consume_skb(skb); + +out_free_dst: + dst_release(reply_dst); + return NET_RX_SUCCESS; + +out_free_skb: + kfree_skb(skb); + return NET_RX_DROP; +} + +static void parp_redo(struct sk_buff *skb) +{ + arp_process(dev_net(skb->dev), NULL, skb); +} + +static int arp_is_multicast(const void *pkey) +{ + return ipv4_is_multicast(*((__be32 *)pkey)); +} + +/* + * Receive an arp request from the device layer. + */ + +static int arp_rcv(struct sk_buff *skb, struct net_device *dev, + struct packet_type *pt, struct net_device *orig_dev) +{ + const struct arphdr *arp; + + /* do not tweak dropwatch on an ARP we will ignore */ + if (dev->flags & IFF_NOARP || + skb->pkt_type == PACKET_OTHERHOST || + skb->pkt_type == PACKET_LOOPBACK) + goto consumeskb; + + skb = skb_share_check(skb, GFP_ATOMIC); + if (!skb) + goto out_of_mem; + + /* ARP header, plus 2 device addresses, plus 2 IP addresses. */ + if (!pskb_may_pull(skb, arp_hdr_len(dev))) + goto freeskb; + + arp = arp_hdr(skb); + if (arp->ar_hln != dev->addr_len || arp->ar_pln != 4) + goto freeskb; + + memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb)); + + return NF_HOOK(NFPROTO_ARP, NF_ARP_IN, + dev_net(dev), NULL, skb, dev, NULL, + arp_process); + +consumeskb: + consume_skb(skb); + return NET_RX_SUCCESS; +freeskb: + kfree_skb(skb); +out_of_mem: + return NET_RX_DROP; +} + +/* + * User level interface (ioctl) + */ + +/* + * Set (create) an ARP cache entry. + */ + +static int arp_req_set_proxy(struct net *net, struct net_device *dev, int on) +{ + if (!dev) { + IPV4_DEVCONF_ALL(net, PROXY_ARP) = on; + return 0; + } + if (__in_dev_get_rtnl(dev)) { + IN_DEV_CONF_SET(__in_dev_get_rtnl(dev), PROXY_ARP, on); + return 0; + } + return -ENXIO; +} + +static int arp_req_set_public(struct net *net, struct arpreq *r, + struct net_device *dev) +{ + __be32 ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; + __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; + + if (mask && mask != htonl(0xFFFFFFFF)) + return -EINVAL; + if (!dev && (r->arp_flags & ATF_COM)) { + dev = dev_getbyhwaddr_rcu(net, r->arp_ha.sa_family, + r->arp_ha.sa_data); + if (!dev) + return -ENODEV; + } + if (mask) { + if (!pneigh_lookup(&arp_tbl, net, &ip, dev, 1)) + return -ENOBUFS; + return 0; + } + + return arp_req_set_proxy(net, dev, 1); +} + +static int arp_req_set(struct net *net, struct arpreq *r, + struct net_device *dev) +{ + __be32 ip; + struct neighbour *neigh; + int err; + + if (r->arp_flags & ATF_PUBL) + return arp_req_set_public(net, r, dev); + + ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; + if (r->arp_flags & ATF_PERM) + r->arp_flags |= ATF_COM; + if (!dev) { + struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); + + if (IS_ERR(rt)) + return PTR_ERR(rt); + dev = rt->dst.dev; + ip_rt_put(rt); + if (!dev) + return -EINVAL; + } + switch (dev->type) { +#if IS_ENABLED(CONFIG_FDDI) + case ARPHRD_FDDI: + /* + * According to RFC 1390, FDDI devices should accept ARP + * hardware types of 1 (Ethernet). However, to be more + * robust, we'll accept hardware types of either 1 (Ethernet) + * or 6 (IEEE 802.2). + */ + if (r->arp_ha.sa_family != ARPHRD_FDDI && + r->arp_ha.sa_family != ARPHRD_ETHER && + r->arp_ha.sa_family != ARPHRD_IEEE802) + return -EINVAL; + break; +#endif + default: + if (r->arp_ha.sa_family != dev->type) + return -EINVAL; + break; + } + + neigh = __neigh_lookup_errno(&arp_tbl, &ip, dev); + err = PTR_ERR(neigh); + if (!IS_ERR(neigh)) { + unsigned int state = NUD_STALE; + if (r->arp_flags & ATF_PERM) + state = NUD_PERMANENT; + err = neigh_update(neigh, (r->arp_flags & ATF_COM) ? + r->arp_ha.sa_data : NULL, state, + NEIGH_UPDATE_F_OVERRIDE | + NEIGH_UPDATE_F_ADMIN, 0); + neigh_release(neigh); + } + return err; +} + +static unsigned int arp_state_to_flags(struct neighbour *neigh) +{ + if (neigh->nud_state&NUD_PERMANENT) + return ATF_PERM | ATF_COM; + else if (neigh->nud_state&NUD_VALID) + return ATF_COM; + else + return 0; +} + +/* + * Get an ARP cache entry. + */ + +static int arp_req_get(struct arpreq *r, struct net_device *dev) +{ + __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; + struct neighbour *neigh; + int err = -ENXIO; + + neigh = neigh_lookup(&arp_tbl, &ip, dev); + if (neigh) { + if (!(READ_ONCE(neigh->nud_state) & NUD_NOARP)) { + read_lock_bh(&neigh->lock); + memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); + r->arp_flags = arp_state_to_flags(neigh); + read_unlock_bh(&neigh->lock); + r->arp_ha.sa_family = dev->type; + strscpy(r->arp_dev, dev->name, sizeof(r->arp_dev)); + err = 0; + } + neigh_release(neigh); + } + return err; +} + +int arp_invalidate(struct net_device *dev, __be32 ip, bool force) +{ + struct neighbour *neigh = neigh_lookup(&arp_tbl, &ip, dev); + int err = -ENXIO; + struct neigh_table *tbl = &arp_tbl; + + if (neigh) { + if ((READ_ONCE(neigh->nud_state) & NUD_VALID) && !force) { + neigh_release(neigh); + return 0; + } + + if (READ_ONCE(neigh->nud_state) & ~NUD_NOARP) + err = neigh_update(neigh, NULL, NUD_FAILED, + NEIGH_UPDATE_F_OVERRIDE| + NEIGH_UPDATE_F_ADMIN, 0); + write_lock_bh(&tbl->lock); + neigh_release(neigh); + neigh_remove_one(neigh, tbl); + write_unlock_bh(&tbl->lock); + } + + return err; +} + +static int arp_req_delete_public(struct net *net, struct arpreq *r, + struct net_device *dev) +{ + __be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr; + __be32 mask = ((struct sockaddr_in *)&r->arp_netmask)->sin_addr.s_addr; + + if (mask == htonl(0xFFFFFFFF)) + return pneigh_delete(&arp_tbl, net, &ip, dev); + + if (mask) + return -EINVAL; + + return arp_req_set_proxy(net, dev, 0); +} + +static int arp_req_delete(struct net *net, struct arpreq *r, + struct net_device *dev) +{ + __be32 ip; + + if (r->arp_flags & ATF_PUBL) + return arp_req_delete_public(net, r, dev); + + ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr; + if (!dev) { + struct rtable *rt = ip_route_output(net, ip, 0, RTO_ONLINK, 0); + if (IS_ERR(rt)) + return PTR_ERR(rt); + dev = rt->dst.dev; + ip_rt_put(rt); + if (!dev) + return -EINVAL; + } + return arp_invalidate(dev, ip, true); +} + +/* + * 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; + fallthrough; + case SIOCGARP: + err = copy_from_user(&r, arg, sizeof(struct arpreq)); + if (err) + return -EFAULT; + break; + default: + return -EINVAL; + } + + if (r.arp_pa.sa_family != AF_INET) + return -EPFNOSUPPORT; + + if (!(r.arp_flags & ATF_PUBL) && + (r.arp_flags & (ATF_NETMASK | ATF_DONTPUB))) + return -EINVAL; + if (!(r.arp_flags & ATF_NETMASK)) + ((struct sockaddr_in *)&r.arp_netmask)->sin_addr.s_addr = + htonl(0xFFFFFFFFUL); + rtnl_lock(); + if (r.arp_dev[0]) { + err = -ENODEV; + dev = __dev_get_by_name(net, r.arp_dev); + if (!dev) + goto out; + + /* Mmmm... It is wrong... ARPHRD_NETROM==0 */ + if (!r.arp_ha.sa_family) + r.arp_ha.sa_family = dev->type; + err = -EINVAL; + if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type) + goto out; + } else if (cmd == SIOCGARP) { + err = -ENODEV; + goto out; + } + + switch (cmd) { + case SIOCDARP: + err = arp_req_delete(net, &r, dev); + break; + case SIOCSARP: + err = arp_req_set(net, &r, dev); + break; + case SIOCGARP: + err = arp_req_get(&r, dev); + break; + } +out: + rtnl_unlock(); + if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r))) + err = -EFAULT; + return err; +} + +static int arp_netdev_event(struct notifier_block *this, unsigned long event, + void *ptr) +{ + struct net_device *dev = netdev_notifier_info_to_dev(ptr); + struct netdev_notifier_change_info *change_info; + struct in_device *in_dev; + bool evict_nocarrier; + + switch (event) { + case NETDEV_CHANGEADDR: + neigh_changeaddr(&arp_tbl, dev); + rt_cache_flush(dev_net(dev)); + break; + case NETDEV_CHANGE: + change_info = ptr; + if (change_info->flags_changed & IFF_NOARP) + neigh_changeaddr(&arp_tbl, dev); + + in_dev = __in_dev_get_rtnl(dev); + if (!in_dev) + evict_nocarrier = true; + else + evict_nocarrier = IN_DEV_ARP_EVICT_NOCARRIER(in_dev); + + if (evict_nocarrier && !netif_carrier_ok(dev)) + neigh_carrier_down(&arp_tbl, dev); + break; + default: + break; + } + + return NOTIFY_DONE; +} + +static struct notifier_block arp_netdev_notifier = { + .notifier_call = arp_netdev_event, +}; + +/* Note, that it is not on notifier chain. + It is necessary, that this routine was called after route cache will be + flushed. + */ +void arp_ifdown(struct net_device *dev) +{ + neigh_ifdown(&arp_tbl, dev); +} + + +/* + * Called once on startup. + */ + +static struct packet_type arp_packet_type __read_mostly = { + .type = cpu_to_be16(ETH_P_ARP), + .func = arp_rcv, +}; + +#ifdef CONFIG_PROC_FS +#if IS_ENABLED(CONFIG_AX25) + +/* + * ax25 -> ASCII conversion + */ +static void ax2asc2(ax25_address *a, char *buf) +{ + char c, *s; + int n; + + for (n = 0, s = buf; n < 6; n++) { + c = (a->ax25_call[n] >> 1) & 0x7F; + + if (c != ' ') + *s++ = c; + } + + *s++ = '-'; + n = (a->ax25_call[6] >> 1) & 0x0F; + if (n > 9) { + *s++ = '1'; + n -= 10; + } + + *s++ = n + '0'; + *s++ = '\0'; + + if (*buf == '\0' || *buf == '-') { + buf[0] = '*'; + buf[1] = '\0'; + } +} +#endif /* CONFIG_AX25 */ + +#define HBUFFERLEN 30 + +static void arp_format_neigh_entry(struct seq_file *seq, + struct neighbour *n) +{ + char hbuffer[HBUFFERLEN]; + int k, j; + char tbuf[16]; + struct net_device *dev = n->dev; + int hatype = dev->type; + + read_lock(&n->lock); + /* Convert hardware address to XX:XX:XX:XX ... form. */ +#if IS_ENABLED(CONFIG_AX25) + if (hatype == ARPHRD_AX25 || hatype == ARPHRD_NETROM) + ax2asc2((ax25_address *)n->ha, hbuffer); + else { +#endif + for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) { + hbuffer[k++] = hex_asc_hi(n->ha[j]); + hbuffer[k++] = hex_asc_lo(n->ha[j]); + hbuffer[k++] = ':'; + } + if (k != 0) + --k; + hbuffer[k] = 0; +#if IS_ENABLED(CONFIG_AX25) + } +#endif + sprintf(tbuf, "%pI4", n->primary_key); + seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s * %s\n", + tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name); + read_unlock(&n->lock); +} + +static void arp_format_pneigh_entry(struct seq_file *seq, + struct pneigh_entry *n) +{ + struct net_device *dev = n->dev; + int hatype = dev ? dev->type : 0; + char tbuf[16]; + + sprintf(tbuf, "%pI4", n->key); + seq_printf(seq, "%-16s 0x%-10x0x%-10x%s * %s\n", + tbuf, hatype, ATF_PUBL | ATF_PERM, "00:00:00:00:00:00", + dev ? dev->name : "*"); +} + +static int arp_seq_show(struct seq_file *seq, void *v) +{ + if (v == SEQ_START_TOKEN) { + seq_puts(seq, "IP address HW type Flags " + "HW address Mask Device\n"); + } else { + struct neigh_seq_state *state = seq->private; + + if (state->flags & NEIGH_SEQ_IS_PNEIGH) + arp_format_pneigh_entry(seq, v); + else + arp_format_neigh_entry(seq, v); + } + + return 0; +} + +static void *arp_seq_start(struct seq_file *seq, loff_t *pos) +{ + /* Don't want to confuse "arp -a" w/ magic entries, + * so we tell the generic iterator to skip NUD_NOARP. + */ + return neigh_seq_start(seq, pos, &arp_tbl, NEIGH_SEQ_SKIP_NOARP); +} + +static const struct seq_operations arp_seq_ops = { + .start = arp_seq_start, + .next = neigh_seq_next, + .stop = neigh_seq_stop, + .show = arp_seq_show, +}; +#endif /* CONFIG_PROC_FS */ + +static int __net_init arp_net_init(struct net *net) +{ + if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops, + sizeof(struct neigh_seq_state))) + return -ENOMEM; + return 0; +} + +static void __net_exit arp_net_exit(struct net *net) +{ + remove_proc_entry("arp", net->proc_net); +} + +static struct pernet_operations arp_net_ops = { + .init = arp_net_init, + .exit = arp_net_exit, +}; + +void __init arp_init(void) +{ + neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl); + + dev_add_pack(&arp_packet_type); + register_pernet_subsys(&arp_net_ops); +#ifdef CONFIG_SYSCTL + neigh_sysctl_register(NULL, &arp_tbl.parms, NULL); +#endif + register_netdevice_notifier(&arp_netdev_notifier); +} |