nf_tables_core.c
/*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Development of this code funded by Astaro AG (http://www.astaro.com/)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/static_key.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_log.h>
static noinline void __nft_trace_packet(struct nft_traceinfo *info,
const struct nft_chain *chain,
enum nft_trace_types type)
{
const struct nft_pktinfo *pkt = info->pkt;
if (!info->trace || !pkt->skb->nf_trace)
return;
info->chain = chain;
info->type = type;
nft_trace_notify(info);
}
static inline void nft_trace_packet(struct nft_traceinfo *info,
const struct nft_chain *chain,
const struct nft_rule *rule,
enum nft_trace_types type)
{
if (static_branch_unlikely(&nft_trace_enabled)) {
info->rule = rule;
__nft_trace_packet(info, chain, type);
}
}
static void nft_cmp_fast_eval(const struct nft_expr *expr,
struct nft_regs *regs)
{
const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
u32 mask = nft_cmp_fast_mask(priv->len);
if ((regs->data[priv->sreg] & mask) == priv->data)
return;
regs->verdict.code = NFT_BREAK;
}
static bool nft_payload_fast_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_payload *priv = nft_expr_priv(expr);
const struct sk_buff *skb = pkt->skb;
u32 *dest = ®s->data[priv->dreg];
unsigned char *ptr;
if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
ptr = skb_network_header(skb);
else {
if (!pkt->tprot_set)
return false;
ptr = skb_network_header(skb) + pkt->xt.thoff;
}
ptr += priv->offset;
if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
return false;
*dest = 0;
if (priv->len == 2)
*(u16 *)dest = *(u16 *)ptr;
else if (priv->len == 4)
*(u32 *)dest = *(u32 *)ptr;
else
*(u8 *)dest = *(u8 *)ptr;
return true;
}
DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
static noinline void nft_update_chain_stats(const struct nft_chain *chain,
const struct nft_pktinfo *pkt)
{
struct nft_base_chain *base_chain;
struct nft_stats *stats;
base_chain = nft_base_chain(chain);
if (!base_chain->stats)
return;
local_bh_disable();
stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
if (stats) {
u64_stats_update_begin(&stats->syncp);
stats->pkts++;
stats->bytes += pkt->skb->len;
u64_stats_update_end(&stats->syncp);
}
local_bh_enable();
}
struct nft_jumpstack {
const struct nft_chain *chain;
struct nft_rule *const *rules;
};
static void expr_call_ops_eval(const struct nft_expr *expr,
struct nft_regs *regs,
struct nft_pktinfo *pkt)
{
unsigned long e = (unsigned long)expr->ops->eval;
if (e == (unsigned long)nft_meta_get_eval)
nft_meta_get_eval(expr, regs, pkt);
else if (e == (unsigned long)nft_lookup_eval)
nft_lookup_eval(expr, regs, pkt);
else
expr->ops->eval(expr, regs, pkt);
}
unsigned int
nft_do_chain(struct nft_pktinfo *pkt, void *priv)
{
const struct nft_chain *chain = priv, *basechain = chain;
const struct net *net = nft_net(pkt);
struct nft_rule *const *rules;
const struct nft_rule *rule;
const struct nft_expr *expr, *last;
struct nft_regs regs;
unsigned int stackptr = 0;
struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
bool genbit = READ_ONCE(net->nft.gencursor);
struct nft_traceinfo info;
info.trace = false;
if (static_branch_unlikely(&nft_trace_enabled))
nft_trace_init(&info, pkt, ®s.verdict, basechain);
do_chain:
if (genbit)
rules = rcu_dereference(chain->rules_gen_1);
else
rules = rcu_dereference(chain->rules_gen_0);
next_rule:
rule = *rules;
regs.verdict.code = NFT_CONTINUE;
for (; *rules ; rules++) {
rule = *rules;
nft_rule_for_each_expr(expr, last, rule) {
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, ®s);
else if (expr->ops != &nft_payload_fast_ops ||
!nft_payload_fast_eval(expr, ®s, pkt))
expr_call_ops_eval(expr, ®s, pkt);
if (regs.verdict.code != NFT_CONTINUE)
break;
}
switch (regs.verdict.code) {
case NFT_BREAK:
regs.verdict.code = NFT_CONTINUE;
continue;
case NFT_CONTINUE:
nft_trace_packet(&info, chain, rule,
NFT_TRACETYPE_RULE);
continue;
}
break;
}
switch (regs.verdict.code & NF_VERDICT_MASK) {
case NF_ACCEPT:
case NF_DROP:
case NF_QUEUE:
case NF_STOLEN:
nft_trace_packet(&info, chain, rule,
NFT_TRACETYPE_RULE);
return regs.verdict.code;
}
switch (regs.verdict.code) {
case NFT_JUMP:
if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
return NF_DROP;
jumpstack[stackptr].chain = chain;
jumpstack[stackptr].rules = rules + 1;
stackptr++;
/* fall through */
case NFT_GOTO:
nft_trace_packet(&info, chain, rule,
NFT_TRACETYPE_RULE);
chain = regs.verdict.chain;
goto do_chain;
case NFT_CONTINUE:
/* fall through */
case NFT_RETURN:
nft_trace_packet(&info, chain, rule,
NFT_TRACETYPE_RETURN);
break;
default:
WARN_ON(1);
}
if (stackptr > 0) {
stackptr--;
chain = jumpstack[stackptr].chain;
rules = jumpstack[stackptr].rules;
goto next_rule;
}
nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
if (static_branch_unlikely(&nft_counters_enabled))
nft_update_chain_stats(basechain, pkt);
return nft_base_chain(basechain)->policy;
}
EXPORT_SYMBOL_GPL(nft_do_chain);
static struct nft_expr_type *nft_basic_types[] = {
&nft_imm_type,
&nft_cmp_type,
&nft_lookup_type,
&nft_bitwise_type,
&nft_byteorder_type,
&nft_payload_type,
&nft_dynset_type,
&nft_range_type,
&nft_meta_type,
&nft_rt_type,
&nft_exthdr_type,
};
int __init nf_tables_core_module_init(void)
{
int err, i;
for (i = 0; i < ARRAY_SIZE(nft_basic_types); i++) {
err = nft_register_expr(nft_basic_types[i]);
if (err)
goto err;
}
return 0;
err:
while (i-- > 0)
nft_unregister_expr(nft_basic_types[i]);
return err;
}
void nf_tables_core_module_exit(void)
{
int i;
i = ARRAY_SIZE(nft_basic_types);
while (i-- > 0)
nft_unregister_expr(nft_basic_types[i]);
}