nf_tables_core.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* 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>
#include <net/netfilter/nft_meta.h>
#if defined(CONFIG_RETPOLINE) && defined(CONFIG_X86)
static struct static_key_false nf_tables_skip_direct_calls;
static bool nf_skip_indirect_calls(void)
{
return static_branch_likely(&nf_tables_skip_direct_calls);
}
static void __init nf_skip_indirect_calls_enable(void)
{
if (!cpu_feature_enabled(X86_FEATURE_RETPOLINE))
static_branch_enable(&nf_tables_skip_direct_calls);
}
#else
static inline bool nf_skip_indirect_calls(void) { return false; }
static inline void nf_skip_indirect_calls_enable(void) { }
#endif
static noinline void __nft_trace_packet(const struct nft_pktinfo *pkt,
const struct nft_verdict *verdict,
const struct nft_rule_dp *rule,
struct nft_traceinfo *info,
enum nft_trace_types type)
{
if (!info->trace || !info->nf_trace)
return;
info->type = type;
nft_trace_notify(pkt, verdict, rule, info);
}
static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
struct nft_verdict *verdict,
struct nft_traceinfo *info,
const struct nft_rule_dp *rule,
enum nft_trace_types type)
{
if (static_branch_unlikely(&nft_trace_enabled)) {
info->nf_trace = pkt->skb->nf_trace;
__nft_trace_packet(pkt, verdict, rule, info, type);
}
}
static inline void nft_trace_copy_nftrace(const struct nft_pktinfo *pkt,
struct nft_traceinfo *info)
{
if (static_branch_unlikely(&nft_trace_enabled))
info->nf_trace = pkt->skb->nf_trace;
}
static void nft_bitwise_fast_eval(const struct nft_expr *expr,
struct nft_regs *regs)
{
const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
u32 *src = ®s->data[priv->sreg];
u32 *dst = ®s->data[priv->dreg];
*dst = (*src & priv->mask) ^ priv->xor;
}
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);
if (((regs->data[priv->sreg] & priv->mask) == priv->data) ^ priv->inv)
return;
regs->verdict.code = NFT_BREAK;
}
static void nft_cmp16_fast_eval(const struct nft_expr *expr,
struct nft_regs *regs)
{
const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
const u64 *reg_data = (const u64 *)®s->data[priv->sreg];
const u64 *mask = (const u64 *)&priv->mask;
const u64 *data = (const u64 *)&priv->data;
if (((reg_data[0] & mask[0]) == data[0] &&
((reg_data[1] & mask[1]) == data[1])) ^ priv->inv)
return;
regs->verdict.code = NFT_BREAK;
}
static noinline void __nft_trace_verdict(const struct nft_pktinfo *pkt,
struct nft_traceinfo *info,
const struct nft_rule_dp *rule,
const struct nft_regs *regs)
{
enum nft_trace_types type;
switch (regs->verdict.code & NF_VERDICT_MASK) {
case NFT_CONTINUE:
case NFT_RETURN:
type = NFT_TRACETYPE_RETURN;
break;
case NF_STOLEN:
type = NFT_TRACETYPE_RULE;
/* can't access skb->nf_trace; use copy */
break;
default:
type = NFT_TRACETYPE_RULE;
if (info->trace)
info->nf_trace = pkt->skb->nf_trace;
break;
}
__nft_trace_packet(pkt, ®s->verdict, rule, info, type);
}
static inline void nft_trace_verdict(const struct nft_pktinfo *pkt,
struct nft_traceinfo *info,
const struct nft_rule_dp *rule,
const struct nft_regs *regs)
{
if (static_branch_unlikely(&nft_trace_enabled))
__nft_trace_verdict(pkt, info, rule, regs);
}
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->flags & NFT_PKTINFO_L4PROTO))
return false;
ptr = skb->data + nft_thoff(pkt);
}
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 __percpu *pstats;
struct nft_stats *stats;
base_chain = nft_base_chain(chain);
pstats = READ_ONCE(base_chain->stats);
if (pstats) {
local_bh_disable();
stats = this_cpu_ptr(pstats);
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_rule_dp *rule;
};
static void expr_call_ops_eval(const struct nft_expr *expr,
struct nft_regs *regs,
struct nft_pktinfo *pkt)
{
#ifdef CONFIG_RETPOLINE
unsigned long e;
if (nf_skip_indirect_calls())
goto indirect_call;
e = (unsigned long)expr->ops->eval;
#define X(e, fun) \
do { if ((e) == (unsigned long)(fun)) \
return fun(expr, regs, pkt); } while (0)
X(e, nft_payload_eval);
X(e, nft_cmp_eval);
X(e, nft_counter_eval);
X(e, nft_meta_get_eval);
X(e, nft_lookup_eval);
#if IS_ENABLED(CONFIG_NFT_CT)
X(e, nft_ct_get_fast_eval);
#endif
X(e, nft_range_eval);
X(e, nft_immediate_eval);
X(e, nft_byteorder_eval);
X(e, nft_dynset_eval);
X(e, nft_rt_get_eval);
X(e, nft_bitwise_eval);
X(e, nft_objref_eval);
X(e, nft_objref_map_eval);
#undef X
indirect_call:
#endif /* CONFIG_RETPOLINE */
expr->ops->eval(expr, regs, pkt);
}
#define nft_rule_expr_first(rule) (struct nft_expr *)&rule->data[0]
#define nft_rule_expr_next(expr) ((void *)expr) + expr->ops->size
#define nft_rule_expr_last(rule) (struct nft_expr *)&rule->data[rule->dlen]
#define nft_rule_dp_for_each_expr(expr, last, rule) \
for ((expr) = nft_rule_expr_first(rule), (last) = nft_rule_expr_last(rule); \
(expr) != (last); \
(expr) = nft_rule_expr_next(expr))
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);
const struct nft_expr *expr, *last;
const struct nft_rule_dp *rule;
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_rule_blob *blob;
struct nft_traceinfo info;
info.trace = false;
if (static_branch_unlikely(&nft_trace_enabled))
nft_trace_init(&info, pkt, basechain);
do_chain:
if (genbit)
blob = rcu_dereference(chain->blob_gen_1);
else
blob = rcu_dereference(chain->blob_gen_0);
rule = (struct nft_rule_dp *)blob->data;
next_rule:
regs.verdict.code = NFT_CONTINUE;
for (; !rule->is_last ; rule = nft_rule_next(rule)) {
nft_rule_dp_for_each_expr(expr, last, rule) {
if (expr->ops == &nft_cmp_fast_ops)
nft_cmp_fast_eval(expr, ®s);
else if (expr->ops == &nft_cmp16_fast_ops)
nft_cmp16_fast_eval(expr, ®s);
else if (expr->ops == &nft_bitwise_fast_ops)
nft_bitwise_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;
nft_trace_copy_nftrace(pkt, &info);
continue;
case NFT_CONTINUE:
nft_trace_packet(pkt, ®s.verdict, &info, rule,
NFT_TRACETYPE_RULE);
continue;
}
break;
}
nft_trace_verdict(pkt, &info, rule, ®s);
switch (regs.verdict.code & NF_VERDICT_MASK) {
case NF_ACCEPT:
case NF_QUEUE:
case NF_STOLEN:
return regs.verdict.code;
case NF_DROP:
return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);
}
switch (regs.verdict.code) {
case NFT_JUMP:
if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
return NF_DROP;
jumpstack[stackptr].rule = nft_rule_next(rule);
stackptr++;
fallthrough;
case NFT_GOTO:
chain = regs.verdict.chain;
goto do_chain;
case NFT_CONTINUE:
case NFT_RETURN:
break;
default:
WARN_ON_ONCE(1);
}
if (stackptr > 0) {
stackptr--;
rule = jumpstack[stackptr].rule;
goto next_rule;
}
nft_trace_packet(pkt, ®s.verdict, &info, NULL, NFT_TRACETYPE_POLICY);
if (static_branch_unlikely(&nft_counters_enabled))
nft_update_chain_stats(basechain, pkt);
if (nft_base_chain(basechain)->policy == NF_DROP)
return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);
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,
&nft_last_type,
&nft_counter_type,
&nft_objref_type,
&nft_inner_type,
};
static struct nft_object_type *nft_basic_objects[] = {
#ifdef CONFIG_NETWORK_SECMARK
&nft_secmark_obj_type,
#endif
&nft_counter_obj_type,
};
int __init nf_tables_core_module_init(void)
{
int err, i, j = 0;
nft_counter_init_seqcount();
for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
err = nft_register_obj(nft_basic_objects[i]);
if (err)
goto err;
}
for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
err = nft_register_expr(nft_basic_types[j]);
if (err)
goto err;
}
nf_skip_indirect_calls_enable();
return 0;
err:
while (j-- > 0)
nft_unregister_expr(nft_basic_types[j]);
while (i-- > 0)
nft_unregister_obj(nft_basic_objects[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]);
i = ARRAY_SIZE(nft_basic_objects);
while (i-- > 0)
nft_unregister_obj(nft_basic_objects[i]);
}