// 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 ([email protected])
* Copyright (C) 2006-2009 Patrick McHardy <[email protected]>
*
*/
#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 <[email protected]>");
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(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
const struct xt_table *table = priv;
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_NETFILTER_XTABLES_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_NETFILTER_XTABLES_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_NETFILTER_XTABLES_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;
strscpy(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_NETFILTER_XTABLES_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 (len < sizeof(tmp))
return -EINVAL;
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;
if ((u64)len < (u64)tmp.size + sizeof(tmp))
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_NETFILTER_XTABLES_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 (len < sizeof(tmp))
return -EINVAL;
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;
if ((u64)len < (u64)tmp.size + sizeof(tmp))
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_NETFILTER_XTABLES_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_NETFILTER_XTABLES_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 *template_ops)
{
struct nf_hook_ops *ops;
unsigned int num_ops;
int ret, i;
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) {
xt_free_table_info(newinfo);
return ret;
}
new_table = xt_register_table(net, table, &bootstrap, newinfo);
if (IS_ERR(new_table)) {
struct arpt_entry *iter;
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
cleanup_entry(iter, net);
xt_free_table_info(newinfo);
return PTR_ERR(new_table);
}
num_ops = hweight32(table->valid_hooks);
if (num_ops == 0) {
ret = -EINVAL;
goto out_free;
}
ops = kmemdup_array(template_ops, num_ops, sizeof(*ops), GFP_KERNEL);
if (!ops) {
ret = -ENOMEM;
goto out_free;
}
for (i = 0; i < num_ops; i++)
ops[i].priv = new_table;
new_table->ops = ops;
ret = nf_register_net_hooks(net, ops, num_ops);
if (ret != 0)
goto out_free;
return ret;
out_free:
__arpt_unregister_table(net, new_table);
return ret;
}
void arpt_unregister_table_pre_exit(struct net *net, const char *name)
{
struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
if (table)
nf_unregister_net_hooks(net, table->ops, hweight32(table->valid_hooks));
}
EXPORT_SYMBOL(arpt_unregister_table_pre_exit);
void arpt_unregister_table(struct net *net, const char *name)
{
struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
if (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_NETFILTER_XTABLES_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);
Codebase Browser
linux