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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Packet matching code for ARP packets.
- *
- * Based heavily, if not almost entirely, upon ip_tables.c framework.
- *
- * Some ARP specific bits are:
- *
- * Copyright (C) 2002 David S. Miller (davem@redhat.com)
- * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
- *
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/kernel.h>
- #include <linux/skbuff.h>
- #include <linux/netdevice.h>
- #include <linux/capability.h>
- #include <linux/if_arp.h>
- #include <linux/kmod.h>
- #include <linux/vmalloc.h>
- #include <linux/proc_fs.h>
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/mutex.h>
- #include <linux/err.h>
- #include <net/compat.h>
- #include <net/sock.h>
- #include <linux/uaccess.h>
- #include <linux/netfilter/x_tables.h>
- #include <linux/netfilter_arp/arp_tables.h>
- #include "../../netfilter/xt_repldata.h"
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
- MODULE_DESCRIPTION("arptables core");
- void *arpt_alloc_initial_table(const struct xt_table *info)
- {
- return xt_alloc_initial_table(arpt, ARPT);
- }
- EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
- static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
- const char *hdr_addr, int len)
- {
- int i, ret;
- if (len > ARPT_DEV_ADDR_LEN_MAX)
- len = ARPT_DEV_ADDR_LEN_MAX;
- ret = 0;
- for (i = 0; i < len; i++)
- ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
- return ret != 0;
- }
- /*
- * Unfortunately, _b and _mask are not aligned to an int (or long int)
- * Some arches dont care, unrolling the loop is a win on them.
- * For other arches, we only have a 16bit alignement.
- */
- static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
- {
- #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
- unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
- #else
- unsigned long ret = 0;
- const u16 *a = (const u16 *)_a;
- const u16 *b = (const u16 *)_b;
- const u16 *mask = (const u16 *)_mask;
- int i;
- for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
- ret |= (a[i] ^ b[i]) & mask[i];
- #endif
- return ret;
- }
- /* Returns whether packet matches rule or not. */
- static inline int arp_packet_match(const struct arphdr *arphdr,
- struct net_device *dev,
- const char *indev,
- const char *outdev,
- const struct arpt_arp *arpinfo)
- {
- const char *arpptr = (char *)(arphdr + 1);
- const char *src_devaddr, *tgt_devaddr;
- __be32 src_ipaddr, tgt_ipaddr;
- long ret;
- if (NF_INVF(arpinfo, ARPT_INV_ARPOP,
- (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop))
- return 0;
- if (NF_INVF(arpinfo, ARPT_INV_ARPHRD,
- (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd))
- return 0;
- if (NF_INVF(arpinfo, ARPT_INV_ARPPRO,
- (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro))
- return 0;
- if (NF_INVF(arpinfo, ARPT_INV_ARPHLN,
- (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln))
- return 0;
- src_devaddr = arpptr;
- arpptr += dev->addr_len;
- memcpy(&src_ipaddr, arpptr, sizeof(u32));
- arpptr += sizeof(u32);
- tgt_devaddr = arpptr;
- arpptr += dev->addr_len;
- memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
- if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR,
- arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr,
- dev->addr_len)) ||
- NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR,
- arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr,
- dev->addr_len)))
- return 0;
- if (NF_INVF(arpinfo, ARPT_INV_SRCIP,
- (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) ||
- NF_INVF(arpinfo, ARPT_INV_TGTIP,
- (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr))
- return 0;
- /* Look for ifname matches. */
- ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
- if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0))
- return 0;
- ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
- if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0))
- return 0;
- return 1;
- }
- static inline int arp_checkentry(const struct arpt_arp *arp)
- {
- if (arp->flags & ~ARPT_F_MASK)
- return 0;
- if (arp->invflags & ~ARPT_INV_MASK)
- return 0;
- return 1;
- }
- static unsigned int
- arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
- {
- net_err_ratelimited("arp_tables: error: '%s'\n",
- (const char *)par->targinfo);
- return NF_DROP;
- }
- static inline const struct xt_entry_target *
- arpt_get_target_c(const struct arpt_entry *e)
- {
- return arpt_get_target((struct arpt_entry *)e);
- }
- static inline struct arpt_entry *
- get_entry(const void *base, unsigned int offset)
- {
- return (struct arpt_entry *)(base + offset);
- }
- static inline
- struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
- {
- return (void *)entry + entry->next_offset;
- }
- unsigned int arpt_do_table(struct sk_buff *skb,
- const struct nf_hook_state *state,
- struct xt_table *table)
- {
- unsigned int hook = state->hook;
- static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
- unsigned int verdict = NF_DROP;
- const struct arphdr *arp;
- struct arpt_entry *e, **jumpstack;
- const char *indev, *outdev;
- const void *table_base;
- unsigned int cpu, stackidx = 0;
- const struct xt_table_info *private;
- struct xt_action_param acpar;
- unsigned int addend;
- if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
- return NF_DROP;
- indev = state->in ? state->in->name : nulldevname;
- outdev = state->out ? state->out->name : nulldevname;
- local_bh_disable();
- addend = xt_write_recseq_begin();
- private = READ_ONCE(table->private); /* Address dependency. */
- cpu = smp_processor_id();
- table_base = private->entries;
- jumpstack = (struct arpt_entry **)private->jumpstack[cpu];
- /* No TEE support for arptables, so no need to switch to alternate
- * stack. All targets that reenter must return absolute verdicts.
- */
- e = get_entry(table_base, private->hook_entry[hook]);
- acpar.state = state;
- acpar.hotdrop = false;
- arp = arp_hdr(skb);
- do {
- const struct xt_entry_target *t;
- struct xt_counters *counter;
- if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
- e = arpt_next_entry(e);
- continue;
- }
- counter = xt_get_this_cpu_counter(&e->counters);
- ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
- t = arpt_get_target_c(e);
- /* Standard target? */
- if (!t->u.kernel.target->target) {
- int v;
- v = ((struct xt_standard_target *)t)->verdict;
- if (v < 0) {
- /* Pop from stack? */
- if (v != XT_RETURN) {
- verdict = (unsigned int)(-v) - 1;
- break;
- }
- if (stackidx == 0) {
- e = get_entry(table_base,
- private->underflow[hook]);
- } else {
- e = jumpstack[--stackidx];
- e = arpt_next_entry(e);
- }
- continue;
- }
- if (table_base + v
- != arpt_next_entry(e)) {
- if (unlikely(stackidx >= private->stacksize)) {
- verdict = NF_DROP;
- break;
- }
- jumpstack[stackidx++] = e;
- }
- e = get_entry(table_base, v);
- continue;
- }
- acpar.target = t->u.kernel.target;
- acpar.targinfo = t->data;
- verdict = t->u.kernel.target->target(skb, &acpar);
- if (verdict == XT_CONTINUE) {
- /* Target might have changed stuff. */
- arp = arp_hdr(skb);
- e = arpt_next_entry(e);
- } else {
- /* Verdict */
- break;
- }
- } while (!acpar.hotdrop);
- xt_write_recseq_end(addend);
- local_bh_enable();
- if (acpar.hotdrop)
- return NF_DROP;
- else
- return verdict;
- }
- /* All zeroes == unconditional rule. */
- static inline bool unconditional(const struct arpt_entry *e)
- {
- static const struct arpt_arp uncond;
- return e->target_offset == sizeof(struct arpt_entry) &&
- memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
- }
- /* Figures out from what hook each rule can be called: returns 0 if
- * there are loops. Puts hook bitmask in comefrom.
- */
- static int mark_source_chains(const struct xt_table_info *newinfo,
- unsigned int valid_hooks, void *entry0,
- unsigned int *offsets)
- {
- unsigned int hook;
- /* No recursion; use packet counter to save back ptrs (reset
- * to 0 as we leave), and comefrom to save source hook bitmask.
- */
- for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
- unsigned int pos = newinfo->hook_entry[hook];
- struct arpt_entry *e = entry0 + pos;
- if (!(valid_hooks & (1 << hook)))
- continue;
- /* Set initial back pointer. */
- e->counters.pcnt = pos;
- for (;;) {
- const struct xt_standard_target *t
- = (void *)arpt_get_target_c(e);
- int visited = e->comefrom & (1 << hook);
- if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
- return 0;
- e->comefrom
- |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
- /* Unconditional return/END. */
- if ((unconditional(e) &&
- (strcmp(t->target.u.user.name,
- XT_STANDARD_TARGET) == 0) &&
- t->verdict < 0) || visited) {
- unsigned int oldpos, size;
- /* Return: backtrack through the last
- * big jump.
- */
- do {
- e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
- oldpos = pos;
- pos = e->counters.pcnt;
- e->counters.pcnt = 0;
- /* We're at the start. */
- if (pos == oldpos)
- goto next;
- e = entry0 + pos;
- } while (oldpos == pos + e->next_offset);
- /* Move along one */
- size = e->next_offset;
- e = entry0 + pos + size;
- if (pos + size >= newinfo->size)
- return 0;
- e->counters.pcnt = pos;
- pos += size;
- } else {
- int newpos = t->verdict;
- if (strcmp(t->target.u.user.name,
- XT_STANDARD_TARGET) == 0 &&
- newpos >= 0) {
- /* This a jump; chase it. */
- if (!xt_find_jump_offset(offsets, newpos,
- newinfo->number))
- return 0;
- } else {
- /* ... this is a fallthru */
- newpos = pos + e->next_offset;
- if (newpos >= newinfo->size)
- return 0;
- }
- e = entry0 + newpos;
- e->counters.pcnt = pos;
- pos = newpos;
- }
- }
- next: ;
- }
- return 1;
- }
- static int check_target(struct arpt_entry *e, struct net *net, const char *name)
- {
- struct xt_entry_target *t = arpt_get_target(e);
- struct xt_tgchk_param par = {
- .net = net,
- .table = name,
- .entryinfo = e,
- .target = t->u.kernel.target,
- .targinfo = t->data,
- .hook_mask = e->comefrom,
- .family = NFPROTO_ARP,
- };
- return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
- }
- static int
- find_check_entry(struct arpt_entry *e, struct net *net, const char *name,
- unsigned int size,
- struct xt_percpu_counter_alloc_state *alloc_state)
- {
- struct xt_entry_target *t;
- struct xt_target *target;
- int ret;
- if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
- return -ENOMEM;
- t = arpt_get_target(e);
- target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
- t->u.user.revision);
- if (IS_ERR(target)) {
- ret = PTR_ERR(target);
- goto out;
- }
- t->u.kernel.target = target;
- ret = check_target(e, net, name);
- if (ret)
- goto err;
- return 0;
- err:
- module_put(t->u.kernel.target->me);
- out:
- xt_percpu_counter_free(&e->counters);
- return ret;
- }
- static bool check_underflow(const struct arpt_entry *e)
- {
- const struct xt_entry_target *t;
- unsigned int verdict;
- if (!unconditional(e))
- return false;
- t = arpt_get_target_c(e);
- if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
- return false;
- verdict = ((struct xt_standard_target *)t)->verdict;
- verdict = -verdict - 1;
- return verdict == NF_DROP || verdict == NF_ACCEPT;
- }
- static inline int check_entry_size_and_hooks(struct arpt_entry *e,
- struct xt_table_info *newinfo,
- const unsigned char *base,
- const unsigned char *limit,
- const unsigned int *hook_entries,
- const unsigned int *underflows,
- unsigned int valid_hooks)
- {
- unsigned int h;
- int err;
- if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
- (unsigned char *)e + e->next_offset > limit)
- return -EINVAL;
- if (e->next_offset
- < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
- return -EINVAL;
- if (!arp_checkentry(&e->arp))
- return -EINVAL;
- err = xt_check_entry_offsets(e, e->elems, e->target_offset,
- e->next_offset);
- if (err)
- return err;
- /* Check hooks & underflows */
- for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
- if (!(valid_hooks & (1 << h)))
- continue;
- if ((unsigned char *)e - base == hook_entries[h])
- newinfo->hook_entry[h] = hook_entries[h];
- if ((unsigned char *)e - base == underflows[h]) {
- if (!check_underflow(e))
- return -EINVAL;
- newinfo->underflow[h] = underflows[h];
- }
- }
- /* Clear counters and comefrom */
- e->counters = ((struct xt_counters) { 0, 0 });
- e->comefrom = 0;
- return 0;
- }
- static void cleanup_entry(struct arpt_entry *e, struct net *net)
- {
- struct xt_tgdtor_param par;
- struct xt_entry_target *t;
- t = arpt_get_target(e);
- par.net = net;
- par.target = t->u.kernel.target;
- par.targinfo = t->data;
- par.family = NFPROTO_ARP;
- if (par.target->destroy != NULL)
- par.target->destroy(&par);
- module_put(par.target->me);
- xt_percpu_counter_free(&e->counters);
- }
- /* Checks and translates the user-supplied table segment (held in
- * newinfo).
- */
- static int translate_table(struct net *net,
- struct xt_table_info *newinfo,
- void *entry0,
- const struct arpt_replace *repl)
- {
- struct xt_percpu_counter_alloc_state alloc_state = { 0 };
- struct arpt_entry *iter;
- unsigned int *offsets;
- unsigned int i;
- int ret = 0;
- newinfo->size = repl->size;
- newinfo->number = repl->num_entries;
- /* Init all hooks to impossible value. */
- for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
- newinfo->hook_entry[i] = 0xFFFFFFFF;
- newinfo->underflow[i] = 0xFFFFFFFF;
- }
- offsets = xt_alloc_entry_offsets(newinfo->number);
- if (!offsets)
- return -ENOMEM;
- i = 0;
- /* Walk through entries, checking offsets. */
- xt_entry_foreach(iter, entry0, newinfo->size) {
- ret = check_entry_size_and_hooks(iter, newinfo, entry0,
- entry0 + repl->size,
- repl->hook_entry,
- repl->underflow,
- repl->valid_hooks);
- if (ret != 0)
- goto out_free;
- if (i < repl->num_entries)
- offsets[i] = (void *)iter - entry0;
- ++i;
- if (strcmp(arpt_get_target(iter)->u.user.name,
- XT_ERROR_TARGET) == 0)
- ++newinfo->stacksize;
- }
- ret = -EINVAL;
- if (i != repl->num_entries)
- goto out_free;
- ret = xt_check_table_hooks(newinfo, repl->valid_hooks);
- if (ret)
- goto out_free;
- if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
- ret = -ELOOP;
- goto out_free;
- }
- kvfree(offsets);
- /* Finally, each sanity check must pass */
- i = 0;
- xt_entry_foreach(iter, entry0, newinfo->size) {
- ret = find_check_entry(iter, net, repl->name, repl->size,
- &alloc_state);
- if (ret != 0)
- break;
- ++i;
- }
- if (ret != 0) {
- xt_entry_foreach(iter, entry0, newinfo->size) {
- if (i-- == 0)
- break;
- cleanup_entry(iter, net);
- }
- return ret;
- }
- return ret;
- out_free:
- kvfree(offsets);
- return ret;
- }
- static void get_counters(const struct xt_table_info *t,
- struct xt_counters counters[])
- {
- struct arpt_entry *iter;
- unsigned int cpu;
- unsigned int i;
- for_each_possible_cpu(cpu) {
- seqcount_t *s = &per_cpu(xt_recseq, cpu);
- i = 0;
- xt_entry_foreach(iter, t->entries, t->size) {
- struct xt_counters *tmp;
- u64 bcnt, pcnt;
- unsigned int start;
- tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
- do {
- start = read_seqcount_begin(s);
- bcnt = tmp->bcnt;
- pcnt = tmp->pcnt;
- } while (read_seqcount_retry(s, start));
- ADD_COUNTER(counters[i], bcnt, pcnt);
- ++i;
- cond_resched();
- }
- }
- }
- static void get_old_counters(const struct xt_table_info *t,
- struct xt_counters counters[])
- {
- struct arpt_entry *iter;
- unsigned int cpu, i;
- for_each_possible_cpu(cpu) {
- i = 0;
- xt_entry_foreach(iter, t->entries, t->size) {
- struct xt_counters *tmp;
- tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
- ADD_COUNTER(counters[i], tmp->bcnt, tmp->pcnt);
- ++i;
- }
- cond_resched();
- }
- }
- static struct xt_counters *alloc_counters(const struct xt_table *table)
- {
- unsigned int countersize;
- struct xt_counters *counters;
- const struct xt_table_info *private = table->private;
- /* We need atomic snapshot of counters: rest doesn't change
- * (other than comefrom, which userspace doesn't care
- * about).
- */
- countersize = sizeof(struct xt_counters) * private->number;
- counters = vzalloc(countersize);
- if (counters == NULL)
- return ERR_PTR(-ENOMEM);
- get_counters(private, counters);
- return counters;
- }
- static int copy_entries_to_user(unsigned int total_size,
- const struct xt_table *table,
- void __user *userptr)
- {
- unsigned int off, num;
- const struct arpt_entry *e;
- struct xt_counters *counters;
- struct xt_table_info *private = table->private;
- int ret = 0;
- void *loc_cpu_entry;
- counters = alloc_counters(table);
- if (IS_ERR(counters))
- return PTR_ERR(counters);
- loc_cpu_entry = private->entries;
- /* FIXME: use iterator macros --RR */
- /* ... then go back and fix counters and names */
- for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
- const struct xt_entry_target *t;
- e = loc_cpu_entry + off;
- if (copy_to_user(userptr + off, e, sizeof(*e))) {
- ret = -EFAULT;
- goto free_counters;
- }
- if (copy_to_user(userptr + off
- + offsetof(struct arpt_entry, counters),
- &counters[num],
- sizeof(counters[num])) != 0) {
- ret = -EFAULT;
- goto free_counters;
- }
- t = arpt_get_target_c(e);
- if (xt_target_to_user(t, userptr + off + e->target_offset)) {
- ret = -EFAULT;
- goto free_counters;
- }
- }
- free_counters:
- vfree(counters);
- return ret;
- }
- #ifdef CONFIG_COMPAT
- static void compat_standard_from_user(void *dst, const void *src)
- {
- int v = *(compat_int_t *)src;
- if (v > 0)
- v += xt_compat_calc_jump(NFPROTO_ARP, v);
- memcpy(dst, &v, sizeof(v));
- }
- static int compat_standard_to_user(void __user *dst, const void *src)
- {
- compat_int_t cv = *(int *)src;
- if (cv > 0)
- cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
- return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
- }
- static int compat_calc_entry(const struct arpt_entry *e,
- const struct xt_table_info *info,
- const void *base, struct xt_table_info *newinfo)
- {
- const struct xt_entry_target *t;
- unsigned int entry_offset;
- int off, i, ret;
- off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
- entry_offset = (void *)e - base;
- t = arpt_get_target_c(e);
- off += xt_compat_target_offset(t->u.kernel.target);
- newinfo->size -= off;
- ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
- if (ret)
- return ret;
- for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
- if (info->hook_entry[i] &&
- (e < (struct arpt_entry *)(base + info->hook_entry[i])))
- newinfo->hook_entry[i] -= off;
- if (info->underflow[i] &&
- (e < (struct arpt_entry *)(base + info->underflow[i])))
- newinfo->underflow[i] -= off;
- }
- return 0;
- }
- static int compat_table_info(const struct xt_table_info *info,
- struct xt_table_info *newinfo)
- {
- struct arpt_entry *iter;
- const void *loc_cpu_entry;
- int ret;
- if (!newinfo || !info)
- return -EINVAL;
- /* we dont care about newinfo->entries */
- memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
- newinfo->initial_entries = 0;
- loc_cpu_entry = info->entries;
- ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
- if (ret)
- return ret;
- xt_entry_foreach(iter, loc_cpu_entry, info->size) {
- ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
- if (ret != 0)
- return ret;
- }
- return 0;
- }
- #endif
- static int get_info(struct net *net, void __user *user, const int *len)
- {
- char name[XT_TABLE_MAXNAMELEN];
- struct xt_table *t;
- int ret;
- if (*len != sizeof(struct arpt_getinfo))
- return -EINVAL;
- if (copy_from_user(name, user, sizeof(name)) != 0)
- return -EFAULT;
- name[XT_TABLE_MAXNAMELEN-1] = '\0';
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- xt_compat_lock(NFPROTO_ARP);
- #endif
- t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
- if (!IS_ERR(t)) {
- struct arpt_getinfo info;
- const struct xt_table_info *private = t->private;
- #ifdef CONFIG_COMPAT
- struct xt_table_info tmp;
- if (in_compat_syscall()) {
- ret = compat_table_info(private, &tmp);
- xt_compat_flush_offsets(NFPROTO_ARP);
- private = &tmp;
- }
- #endif
- memset(&info, 0, sizeof(info));
- info.valid_hooks = t->valid_hooks;
- memcpy(info.hook_entry, private->hook_entry,
- sizeof(info.hook_entry));
- memcpy(info.underflow, private->underflow,
- sizeof(info.underflow));
- info.num_entries = private->number;
- info.size = private->size;
- strcpy(info.name, name);
- if (copy_to_user(user, &info, *len) != 0)
- ret = -EFAULT;
- else
- ret = 0;
- xt_table_unlock(t);
- module_put(t->me);
- } else
- ret = PTR_ERR(t);
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- xt_compat_unlock(NFPROTO_ARP);
- #endif
- return ret;
- }
- static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
- const int *len)
- {
- int ret;
- struct arpt_get_entries get;
- struct xt_table *t;
- if (*len < sizeof(get))
- return -EINVAL;
- if (copy_from_user(&get, uptr, sizeof(get)) != 0)
- return -EFAULT;
- if (*len != sizeof(struct arpt_get_entries) + get.size)
- return -EINVAL;
- get.name[sizeof(get.name) - 1] = '\0';
- t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
- if (!IS_ERR(t)) {
- const struct xt_table_info *private = t->private;
- if (get.size == private->size)
- ret = copy_entries_to_user(private->size,
- t, uptr->entrytable);
- else
- ret = -EAGAIN;
- module_put(t->me);
- xt_table_unlock(t);
- } else
- ret = PTR_ERR(t);
- return ret;
- }
- static int __do_replace(struct net *net, const char *name,
- unsigned int valid_hooks,
- struct xt_table_info *newinfo,
- unsigned int num_counters,
- void __user *counters_ptr)
- {
- int ret;
- struct xt_table *t;
- struct xt_table_info *oldinfo;
- struct xt_counters *counters;
- void *loc_cpu_old_entry;
- struct arpt_entry *iter;
- ret = 0;
- counters = xt_counters_alloc(num_counters);
- if (!counters) {
- ret = -ENOMEM;
- goto out;
- }
- t = xt_request_find_table_lock(net, NFPROTO_ARP, name);
- if (IS_ERR(t)) {
- ret = PTR_ERR(t);
- goto free_newinfo_counters_untrans;
- }
- /* You lied! */
- if (valid_hooks != t->valid_hooks) {
- ret = -EINVAL;
- goto put_module;
- }
- oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
- if (!oldinfo)
- goto put_module;
- /* Update module usage count based on number of rules */
- if ((oldinfo->number > oldinfo->initial_entries) ||
- (newinfo->number <= oldinfo->initial_entries))
- module_put(t->me);
- if ((oldinfo->number > oldinfo->initial_entries) &&
- (newinfo->number <= oldinfo->initial_entries))
- module_put(t->me);
- xt_table_unlock(t);
- get_old_counters(oldinfo, counters);
- /* Decrease module usage counts and free resource */
- loc_cpu_old_entry = oldinfo->entries;
- xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
- cleanup_entry(iter, net);
- xt_free_table_info(oldinfo);
- if (copy_to_user(counters_ptr, counters,
- sizeof(struct xt_counters) * num_counters) != 0) {
- /* Silent error, can't fail, new table is already in place */
- net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
- }
- vfree(counters);
- return ret;
- put_module:
- module_put(t->me);
- xt_table_unlock(t);
- free_newinfo_counters_untrans:
- vfree(counters);
- out:
- return ret;
- }
- static int do_replace(struct net *net, sockptr_t arg, unsigned int len)
- {
- int ret;
- struct arpt_replace tmp;
- struct xt_table_info *newinfo;
- void *loc_cpu_entry;
- struct arpt_entry *iter;
- if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
- return -EFAULT;
- /* overflow check */
- if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
- return -ENOMEM;
- if (tmp.num_counters == 0)
- return -EINVAL;
- tmp.name[sizeof(tmp.name)-1] = 0;
- newinfo = xt_alloc_table_info(tmp.size);
- if (!newinfo)
- return -ENOMEM;
- loc_cpu_entry = newinfo->entries;
- if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
- tmp.size) != 0) {
- ret = -EFAULT;
- goto free_newinfo;
- }
- ret = translate_table(net, newinfo, loc_cpu_entry, &tmp);
- if (ret != 0)
- goto free_newinfo;
- ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
- tmp.num_counters, tmp.counters);
- if (ret)
- goto free_newinfo_untrans;
- return 0;
- free_newinfo_untrans:
- xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
- cleanup_entry(iter, net);
- free_newinfo:
- xt_free_table_info(newinfo);
- return ret;
- }
- static int do_add_counters(struct net *net, sockptr_t arg, unsigned int len)
- {
- unsigned int i;
- struct xt_counters_info tmp;
- struct xt_counters *paddc;
- struct xt_table *t;
- const struct xt_table_info *private;
- int ret = 0;
- struct arpt_entry *iter;
- unsigned int addend;
- paddc = xt_copy_counters(arg, len, &tmp);
- if (IS_ERR(paddc))
- return PTR_ERR(paddc);
- t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
- if (IS_ERR(t)) {
- ret = PTR_ERR(t);
- goto free;
- }
- local_bh_disable();
- private = t->private;
- if (private->number != tmp.num_counters) {
- ret = -EINVAL;
- goto unlock_up_free;
- }
- i = 0;
- addend = xt_write_recseq_begin();
- xt_entry_foreach(iter, private->entries, private->size) {
- struct xt_counters *tmp;
- tmp = xt_get_this_cpu_counter(&iter->counters);
- ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
- ++i;
- }
- xt_write_recseq_end(addend);
- unlock_up_free:
- local_bh_enable();
- xt_table_unlock(t);
- module_put(t->me);
- free:
- vfree(paddc);
- return ret;
- }
- #ifdef CONFIG_COMPAT
- struct compat_arpt_replace {
- char name[XT_TABLE_MAXNAMELEN];
- u32 valid_hooks;
- u32 num_entries;
- u32 size;
- u32 hook_entry[NF_ARP_NUMHOOKS];
- u32 underflow[NF_ARP_NUMHOOKS];
- u32 num_counters;
- compat_uptr_t counters;
- struct compat_arpt_entry entries[];
- };
- static inline void compat_release_entry(struct compat_arpt_entry *e)
- {
- struct xt_entry_target *t;
- t = compat_arpt_get_target(e);
- module_put(t->u.kernel.target->me);
- }
- static int
- check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
- struct xt_table_info *newinfo,
- unsigned int *size,
- const unsigned char *base,
- const unsigned char *limit)
- {
- struct xt_entry_target *t;
- struct xt_target *target;
- unsigned int entry_offset;
- int ret, off;
- if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
- (unsigned char *)e + e->next_offset > limit)
- return -EINVAL;
- if (e->next_offset < sizeof(struct compat_arpt_entry) +
- sizeof(struct compat_xt_entry_target))
- return -EINVAL;
- if (!arp_checkentry(&e->arp))
- return -EINVAL;
- ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
- e->next_offset);
- if (ret)
- return ret;
- off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
- entry_offset = (void *)e - (void *)base;
- t = compat_arpt_get_target(e);
- target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
- t->u.user.revision);
- if (IS_ERR(target)) {
- ret = PTR_ERR(target);
- goto out;
- }
- t->u.kernel.target = target;
- off += xt_compat_target_offset(target);
- *size += off;
- ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
- if (ret)
- goto release_target;
- return 0;
- release_target:
- module_put(t->u.kernel.target->me);
- out:
- return ret;
- }
- static void
- compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
- unsigned int *size,
- struct xt_table_info *newinfo, unsigned char *base)
- {
- struct xt_entry_target *t;
- struct arpt_entry *de;
- unsigned int origsize;
- int h;
- origsize = *size;
- de = *dstptr;
- memcpy(de, e, sizeof(struct arpt_entry));
- memcpy(&de->counters, &e->counters, sizeof(e->counters));
- *dstptr += sizeof(struct arpt_entry);
- *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
- de->target_offset = e->target_offset - (origsize - *size);
- t = compat_arpt_get_target(e);
- xt_compat_target_from_user(t, dstptr, size);
- de->next_offset = e->next_offset - (origsize - *size);
- for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
- if ((unsigned char *)de - base < newinfo->hook_entry[h])
- newinfo->hook_entry[h] -= origsize - *size;
- if ((unsigned char *)de - base < newinfo->underflow[h])
- newinfo->underflow[h] -= origsize - *size;
- }
- }
- static int translate_compat_table(struct net *net,
- struct xt_table_info **pinfo,
- void **pentry0,
- const struct compat_arpt_replace *compatr)
- {
- unsigned int i, j;
- struct xt_table_info *newinfo, *info;
- void *pos, *entry0, *entry1;
- struct compat_arpt_entry *iter0;
- struct arpt_replace repl;
- unsigned int size;
- int ret;
- info = *pinfo;
- entry0 = *pentry0;
- size = compatr->size;
- info->number = compatr->num_entries;
- j = 0;
- xt_compat_lock(NFPROTO_ARP);
- ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
- if (ret)
- goto out_unlock;
- /* Walk through entries, checking offsets. */
- xt_entry_foreach(iter0, entry0, compatr->size) {
- ret = check_compat_entry_size_and_hooks(iter0, info, &size,
- entry0,
- entry0 + compatr->size);
- if (ret != 0)
- goto out_unlock;
- ++j;
- }
- ret = -EINVAL;
- if (j != compatr->num_entries)
- goto out_unlock;
- ret = -ENOMEM;
- newinfo = xt_alloc_table_info(size);
- if (!newinfo)
- goto out_unlock;
- memset(newinfo->entries, 0, size);
- newinfo->number = compatr->num_entries;
- for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
- newinfo->hook_entry[i] = compatr->hook_entry[i];
- newinfo->underflow[i] = compatr->underflow[i];
- }
- entry1 = newinfo->entries;
- pos = entry1;
- size = compatr->size;
- xt_entry_foreach(iter0, entry0, compatr->size)
- compat_copy_entry_from_user(iter0, &pos, &size,
- newinfo, entry1);
- /* all module references in entry0 are now gone */
- xt_compat_flush_offsets(NFPROTO_ARP);
- xt_compat_unlock(NFPROTO_ARP);
- memcpy(&repl, compatr, sizeof(*compatr));
- for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
- repl.hook_entry[i] = newinfo->hook_entry[i];
- repl.underflow[i] = newinfo->underflow[i];
- }
- repl.num_counters = 0;
- repl.counters = NULL;
- repl.size = newinfo->size;
- ret = translate_table(net, newinfo, entry1, &repl);
- if (ret)
- goto free_newinfo;
- *pinfo = newinfo;
- *pentry0 = entry1;
- xt_free_table_info(info);
- return 0;
- free_newinfo:
- xt_free_table_info(newinfo);
- return ret;
- out_unlock:
- xt_compat_flush_offsets(NFPROTO_ARP);
- xt_compat_unlock(NFPROTO_ARP);
- xt_entry_foreach(iter0, entry0, compatr->size) {
- if (j-- == 0)
- break;
- compat_release_entry(iter0);
- }
- return ret;
- }
- static int compat_do_replace(struct net *net, sockptr_t arg, unsigned int len)
- {
- int ret;
- struct compat_arpt_replace tmp;
- struct xt_table_info *newinfo;
- void *loc_cpu_entry;
- struct arpt_entry *iter;
- if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
- return -EFAULT;
- /* overflow check */
- if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
- return -ENOMEM;
- if (tmp.num_counters == 0)
- return -EINVAL;
- tmp.name[sizeof(tmp.name)-1] = 0;
- newinfo = xt_alloc_table_info(tmp.size);
- if (!newinfo)
- return -ENOMEM;
- loc_cpu_entry = newinfo->entries;
- if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
- tmp.size) != 0) {
- ret = -EFAULT;
- goto free_newinfo;
- }
- ret = translate_compat_table(net, &newinfo, &loc_cpu_entry, &tmp);
- if (ret != 0)
- goto free_newinfo;
- ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
- tmp.num_counters, compat_ptr(tmp.counters));
- if (ret)
- goto free_newinfo_untrans;
- return 0;
- free_newinfo_untrans:
- xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
- cleanup_entry(iter, net);
- free_newinfo:
- xt_free_table_info(newinfo);
- return ret;
- }
- static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
- compat_uint_t *size,
- struct xt_counters *counters,
- unsigned int i)
- {
- struct xt_entry_target *t;
- struct compat_arpt_entry __user *ce;
- u_int16_t target_offset, next_offset;
- compat_uint_t origsize;
- int ret;
- origsize = *size;
- ce = *dstptr;
- if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
- copy_to_user(&ce->counters, &counters[i],
- sizeof(counters[i])) != 0)
- return -EFAULT;
- *dstptr += sizeof(struct compat_arpt_entry);
- *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
- target_offset = e->target_offset - (origsize - *size);
- t = arpt_get_target(e);
- ret = xt_compat_target_to_user(t, dstptr, size);
- if (ret)
- return ret;
- next_offset = e->next_offset - (origsize - *size);
- if (put_user(target_offset, &ce->target_offset) != 0 ||
- put_user(next_offset, &ce->next_offset) != 0)
- return -EFAULT;
- return 0;
- }
- static int compat_copy_entries_to_user(unsigned int total_size,
- struct xt_table *table,
- void __user *userptr)
- {
- struct xt_counters *counters;
- const struct xt_table_info *private = table->private;
- void __user *pos;
- unsigned int size;
- int ret = 0;
- unsigned int i = 0;
- struct arpt_entry *iter;
- counters = alloc_counters(table);
- if (IS_ERR(counters))
- return PTR_ERR(counters);
- pos = userptr;
- size = total_size;
- xt_entry_foreach(iter, private->entries, total_size) {
- ret = compat_copy_entry_to_user(iter, &pos,
- &size, counters, i++);
- if (ret != 0)
- break;
- }
- vfree(counters);
- return ret;
- }
- struct compat_arpt_get_entries {
- char name[XT_TABLE_MAXNAMELEN];
- compat_uint_t size;
- struct compat_arpt_entry entrytable[];
- };
- static int compat_get_entries(struct net *net,
- struct compat_arpt_get_entries __user *uptr,
- int *len)
- {
- int ret;
- struct compat_arpt_get_entries get;
- struct xt_table *t;
- if (*len < sizeof(get))
- return -EINVAL;
- if (copy_from_user(&get, uptr, sizeof(get)) != 0)
- return -EFAULT;
- if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
- return -EINVAL;
- get.name[sizeof(get.name) - 1] = '\0';
- xt_compat_lock(NFPROTO_ARP);
- t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
- if (!IS_ERR(t)) {
- const struct xt_table_info *private = t->private;
- struct xt_table_info info;
- ret = compat_table_info(private, &info);
- if (!ret && get.size == info.size) {
- ret = compat_copy_entries_to_user(private->size,
- t, uptr->entrytable);
- } else if (!ret)
- ret = -EAGAIN;
- xt_compat_flush_offsets(NFPROTO_ARP);
- module_put(t->me);
- xt_table_unlock(t);
- } else
- ret = PTR_ERR(t);
- xt_compat_unlock(NFPROTO_ARP);
- return ret;
- }
- #endif
- static int do_arpt_set_ctl(struct sock *sk, int cmd, sockptr_t arg,
- unsigned int len)
- {
- int ret;
- if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
- return -EPERM;
- switch (cmd) {
- case ARPT_SO_SET_REPLACE:
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- ret = compat_do_replace(sock_net(sk), arg, len);
- else
- #endif
- ret = do_replace(sock_net(sk), arg, len);
- break;
- case ARPT_SO_SET_ADD_COUNTERS:
- ret = do_add_counters(sock_net(sk), arg, len);
- break;
- default:
- ret = -EINVAL;
- }
- return ret;
- }
- static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
- {
- int ret;
- if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
- return -EPERM;
- switch (cmd) {
- case ARPT_SO_GET_INFO:
- ret = get_info(sock_net(sk), user, len);
- break;
- case ARPT_SO_GET_ENTRIES:
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- ret = compat_get_entries(sock_net(sk), user, len);
- else
- #endif
- ret = get_entries(sock_net(sk), user, len);
- break;
- case ARPT_SO_GET_REVISION_TARGET: {
- struct xt_get_revision rev;
- if (*len != sizeof(rev)) {
- ret = -EINVAL;
- break;
- }
- if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
- ret = -EFAULT;
- break;
- }
- rev.name[sizeof(rev.name)-1] = 0;
- try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
- rev.revision, 1, &ret),
- "arpt_%s", rev.name);
- break;
- }
- default:
- ret = -EINVAL;
- }
- return ret;
- }
- static void __arpt_unregister_table(struct net *net, struct xt_table *table)
- {
- struct xt_table_info *private;
- void *loc_cpu_entry;
- struct module *table_owner = table->me;
- struct arpt_entry *iter;
- private = xt_unregister_table(table);
- /* Decrease module usage counts and free resources */
- loc_cpu_entry = private->entries;
- xt_entry_foreach(iter, loc_cpu_entry, private->size)
- cleanup_entry(iter, net);
- if (private->number > private->initial_entries)
- module_put(table_owner);
- xt_free_table_info(private);
- }
- int arpt_register_table(struct net *net,
- const struct xt_table *table,
- const struct arpt_replace *repl,
- const struct nf_hook_ops *ops,
- struct xt_table **res)
- {
- int ret;
- struct xt_table_info *newinfo;
- struct xt_table_info bootstrap = {0};
- void *loc_cpu_entry;
- struct xt_table *new_table;
- newinfo = xt_alloc_table_info(repl->size);
- if (!newinfo)
- return -ENOMEM;
- loc_cpu_entry = newinfo->entries;
- memcpy(loc_cpu_entry, repl->entries, repl->size);
- ret = translate_table(net, newinfo, loc_cpu_entry, repl);
- if (ret != 0)
- goto out_free;
- new_table = xt_register_table(net, table, &bootstrap, newinfo);
- if (IS_ERR(new_table)) {
- ret = PTR_ERR(new_table);
- goto out_free;
- }
- /* set res now, will see skbs right after nf_register_net_hooks */
- WRITE_ONCE(*res, new_table);
- ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
- if (ret != 0) {
- __arpt_unregister_table(net, new_table);
- *res = NULL;
- }
- return ret;
- out_free:
- xt_free_table_info(newinfo);
- return ret;
- }
- void arpt_unregister_table_pre_exit(struct net *net, struct xt_table *table,
- const struct nf_hook_ops *ops)
- {
- nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
- }
- EXPORT_SYMBOL(arpt_unregister_table_pre_exit);
- void arpt_unregister_table(struct net *net, struct xt_table *table)
- {
- __arpt_unregister_table(net, table);
- }
- /* The built-in targets: standard (NULL) and error. */
- static struct xt_target arpt_builtin_tg[] __read_mostly = {
- {
- .name = XT_STANDARD_TARGET,
- .targetsize = sizeof(int),
- .family = NFPROTO_ARP,
- #ifdef CONFIG_COMPAT
- .compatsize = sizeof(compat_int_t),
- .compat_from_user = compat_standard_from_user,
- .compat_to_user = compat_standard_to_user,
- #endif
- },
- {
- .name = XT_ERROR_TARGET,
- .target = arpt_error,
- .targetsize = XT_FUNCTION_MAXNAMELEN,
- .family = NFPROTO_ARP,
- },
- };
- static struct nf_sockopt_ops arpt_sockopts = {
- .pf = PF_INET,
- .set_optmin = ARPT_BASE_CTL,
- .set_optmax = ARPT_SO_SET_MAX+1,
- .set = do_arpt_set_ctl,
- .get_optmin = ARPT_BASE_CTL,
- .get_optmax = ARPT_SO_GET_MAX+1,
- .get = do_arpt_get_ctl,
- .owner = THIS_MODULE,
- };
- static int __net_init arp_tables_net_init(struct net *net)
- {
- return xt_proto_init(net, NFPROTO_ARP);
- }
- static void __net_exit arp_tables_net_exit(struct net *net)
- {
- xt_proto_fini(net, NFPROTO_ARP);
- }
- static struct pernet_operations arp_tables_net_ops = {
- .init = arp_tables_net_init,
- .exit = arp_tables_net_exit,
- };
- static int __init arp_tables_init(void)
- {
- int ret;
- ret = register_pernet_subsys(&arp_tables_net_ops);
- if (ret < 0)
- goto err1;
- /* No one else will be downing sem now, so we won't sleep */
- ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
- if (ret < 0)
- goto err2;
- /* Register setsockopt */
- ret = nf_register_sockopt(&arpt_sockopts);
- if (ret < 0)
- goto err4;
- return 0;
- err4:
- xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
- err2:
- unregister_pernet_subsys(&arp_tables_net_ops);
- err1:
- return ret;
- }
- static void __exit arp_tables_fini(void)
- {
- nf_unregister_sockopt(&arpt_sockopts);
- xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
- unregister_pernet_subsys(&arp_tables_net_ops);
- }
- EXPORT_SYMBOL(arpt_register_table);
- EXPORT_SYMBOL(arpt_unregister_table);
- EXPORT_SYMBOL(arpt_do_table);
- module_init(arp_tables_init);
- module_exit(arp_tables_fini);
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