// SPDX-License-Identifier: GPL-2.0-only
/* Connection state tracking for netfilter. This is separated from,
but required by, the NAT layer; it can also be used by an iptables
extension. */
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <[email protected]>
* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
* (C) 2005-2012 Patrick McHardy <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/vmalloc.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/siphash.h>
#include <linux/err.h>
#include <linux/percpu.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/socket.h>
#include <linux/mm.h>
#include <linux/nsproxy.h>
#include <linux/rculist_nulls.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_bpf.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_acct.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/nf_conntrack_timestamp.h>
#include <net/netfilter/nf_conntrack_timeout.h>
#include <net/netfilter/nf_conntrack_labels.h>
#include <net/netfilter/nf_conntrack_synproxy.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netns/hash.h>
#include <net/ip.h>
#include "nf_internals.h"
__cacheline_aligned_in_smp spinlock_t nf_conntrack_locks[CONNTRACK_LOCKS];
EXPORT_SYMBOL_GPL(nf_conntrack_locks);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(nf_conntrack_expect_lock);
EXPORT_SYMBOL_GPL(nf_conntrack_expect_lock);
struct hlist_nulls_head *nf_conntrack_hash __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_hash);
struct conntrack_gc_work {
struct delayed_work dwork;
u32 next_bucket;
u32 avg_timeout;
u32 count;
u32 start_time;
bool exiting;
bool early_drop;
};
static __read_mostly struct kmem_cache *nf_conntrack_cachep;
static DEFINE_SPINLOCK(nf_conntrack_locks_all_lock);
static __read_mostly bool nf_conntrack_locks_all;
/* serialize hash resizes and nf_ct_iterate_cleanup */
static DEFINE_MUTEX(nf_conntrack_mutex);
#define GC_SCAN_INTERVAL_MAX (60ul * HZ)
#define GC_SCAN_INTERVAL_MIN (1ul * HZ)
/* clamp timeouts to this value (TCP unacked) */
#define GC_SCAN_INTERVAL_CLAMP (300ul * HZ)
/* Initial bias pretending we have 100 entries at the upper bound so we don't
* wakeup often just because we have three entries with a 1s timeout while still
* allowing non-idle machines to wakeup more often when needed.
*/
#define GC_SCAN_INITIAL_COUNT 100
#define GC_SCAN_INTERVAL_INIT GC_SCAN_INTERVAL_MAX
#define GC_SCAN_MAX_DURATION msecs_to_jiffies(10)
#define GC_SCAN_EXPIRED_MAX (64000u / HZ)
#define MIN_CHAINLEN 50u
#define MAX_CHAINLEN (80u - MIN_CHAINLEN)
static struct conntrack_gc_work conntrack_gc_work;
void nf_conntrack_lock(spinlock_t *lock) __acquires(lock)
{
/* 1) Acquire the lock */
spin_lock(lock);
/* 2) read nf_conntrack_locks_all, with ACQUIRE semantics
* It pairs with the smp_store_release() in nf_conntrack_all_unlock()
*/
if (likely(smp_load_acquire(&nf_conntrack_locks_all) == false))
return;
/* fast path failed, unlock */
spin_unlock(lock);
/* Slow path 1) get global lock */
spin_lock(&nf_conntrack_locks_all_lock);
/* Slow path 2) get the lock we want */
spin_lock(lock);
/* Slow path 3) release the global lock */
spin_unlock(&nf_conntrack_locks_all_lock);
}
EXPORT_SYMBOL_GPL(nf_conntrack_lock);
static void nf_conntrack_double_unlock(unsigned int h1, unsigned int h2)
{
h1 %= CONNTRACK_LOCKS;
h2 %= CONNTRACK_LOCKS;
spin_unlock(&nf_conntrack_locks[h1]);
if (h1 != h2)
spin_unlock(&nf_conntrack_locks[h2]);
}
/* return true if we need to recompute hashes (in case hash table was resized) */
static bool nf_conntrack_double_lock(struct net *net, unsigned int h1,
unsigned int h2, unsigned int sequence)
{
h1 %= CONNTRACK_LOCKS;
h2 %= CONNTRACK_LOCKS;
if (h1 <= h2) {
nf_conntrack_lock(&nf_conntrack_locks[h1]);
if (h1 != h2)
spin_lock_nested(&nf_conntrack_locks[h2],
SINGLE_DEPTH_NESTING);
} else {
nf_conntrack_lock(&nf_conntrack_locks[h2]);
spin_lock_nested(&nf_conntrack_locks[h1],
SINGLE_DEPTH_NESTING);
}
if (read_seqcount_retry(&nf_conntrack_generation, sequence)) {
nf_conntrack_double_unlock(h1, h2);
return true;
}
return false;
}
static void nf_conntrack_all_lock(void)
__acquires(&nf_conntrack_locks_all_lock)
{
int i;
spin_lock(&nf_conntrack_locks_all_lock);
/* For nf_contrack_locks_all, only the latest time when another
* CPU will see an update is controlled, by the "release" of the
* spin_lock below.
* The earliest time is not controlled, an thus KCSAN could detect
* a race when nf_conntract_lock() reads the variable.
* WRITE_ONCE() is used to ensure the compiler will not
* optimize the write.
*/
WRITE_ONCE(nf_conntrack_locks_all, true);
for (i = 0; i < CONNTRACK_LOCKS; i++) {
spin_lock(&nf_conntrack_locks[i]);
/* This spin_unlock provides the "release" to ensure that
* nf_conntrack_locks_all==true is visible to everyone that
* acquired spin_lock(&nf_conntrack_locks[]).
*/
spin_unlock(&nf_conntrack_locks[i]);
}
}
static void nf_conntrack_all_unlock(void)
__releases(&nf_conntrack_locks_all_lock)
{
/* All prior stores must be complete before we clear
* 'nf_conntrack_locks_all'. Otherwise nf_conntrack_lock()
* might observe the false value but not the entire
* critical section.
* It pairs with the smp_load_acquire() in nf_conntrack_lock()
*/
smp_store_release(&nf_conntrack_locks_all, false);
spin_unlock(&nf_conntrack_locks_all_lock);
}
unsigned int nf_conntrack_htable_size __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
unsigned int nf_conntrack_max __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_max);
seqcount_spinlock_t nf_conntrack_generation __read_mostly;
static siphash_aligned_key_t nf_conntrack_hash_rnd;
static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple,
unsigned int zoneid,
const struct net *net)
{
siphash_key_t key;
get_random_once(&nf_conntrack_hash_rnd, sizeof(nf_conntrack_hash_rnd));
key = nf_conntrack_hash_rnd;
key.key[0] ^= zoneid;
key.key[1] ^= net_hash_mix(net);
return siphash((void *)tuple,
offsetofend(struct nf_conntrack_tuple, dst.__nfct_hash_offsetend),
&key);
}
static u32 scale_hash(u32 hash)
{
return reciprocal_scale(hash, nf_conntrack_htable_size);
}
static u32 __hash_conntrack(const struct net *net,
const struct nf_conntrack_tuple *tuple,
unsigned int zoneid,
unsigned int size)
{
return reciprocal_scale(hash_conntrack_raw(tuple, zoneid, net), size);
}
static u32 hash_conntrack(const struct net *net,
const struct nf_conntrack_tuple *tuple,
unsigned int zoneid)
{
return scale_hash(hash_conntrack_raw(tuple, zoneid, net));
}
static bool nf_ct_get_tuple_ports(const struct sk_buff *skb,
unsigned int dataoff,
struct nf_conntrack_tuple *tuple)
{ struct {
__be16 sport;
__be16 dport;
} _inet_hdr, *inet_hdr;
/* Actually only need first 4 bytes to get ports. */
inet_hdr = skb_header_pointer(skb, dataoff, sizeof(_inet_hdr), &_inet_hdr);
if (!inet_hdr)
return false;
tuple->src.u.udp.port = inet_hdr->sport;
tuple->dst.u.udp.port = inet_hdr->dport;
return true;
}
static bool
nf_ct_get_tuple(const struct sk_buff *skb,
unsigned int nhoff,
unsigned int dataoff,
u_int16_t l3num,
u_int8_t protonum,
struct net *net,
struct nf_conntrack_tuple *tuple)
{
unsigned int size;
const __be32 *ap;
__be32 _addrs[8];
memset(tuple, 0, sizeof(*tuple));
tuple->src.l3num = l3num;
switch (l3num) {
case NFPROTO_IPV4:
nhoff += offsetof(struct iphdr, saddr);
size = 2 * sizeof(__be32);
break;
case NFPROTO_IPV6:
nhoff += offsetof(struct ipv6hdr, saddr);
size = sizeof(_addrs);
break;
default:
return true;
}
ap = skb_header_pointer(skb, nhoff, size, _addrs);
if (!ap)
return false;
switch (l3num) {
case NFPROTO_IPV4:
tuple->src.u3.ip = ap[0];
tuple->dst.u3.ip = ap[1];
break;
case NFPROTO_IPV6:
memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
break;
}
tuple->dst.protonum = protonum;
tuple->dst.dir = IP_CT_DIR_ORIGINAL;
switch (protonum) {
#if IS_ENABLED(CONFIG_IPV6)
case IPPROTO_ICMPV6:
return icmpv6_pkt_to_tuple(skb, dataoff, net, tuple);
#endif
case IPPROTO_ICMP:
return icmp_pkt_to_tuple(skb, dataoff, net, tuple);
#ifdef CONFIG_NF_CT_PROTO_GRE
case IPPROTO_GRE:
return gre_pkt_to_tuple(skb, dataoff, net, tuple);
#endif
case IPPROTO_TCP:
case IPPROTO_UDP:
#ifdef CONFIG_NF_CT_PROTO_UDPLITE
case IPPROTO_UDPLITE:
#endif
#ifdef CONFIG_NF_CT_PROTO_SCTP
case IPPROTO_SCTP:
#endif
#ifdef CONFIG_NF_CT_PROTO_DCCP
case IPPROTO_DCCP:
#endif
/* fallthrough */
return nf_ct_get_tuple_ports(skb, dataoff, tuple);
default:
break;
}
return true;
}
static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
u_int8_t *protonum)
{
int dataoff = -1;
const struct iphdr *iph;
struct iphdr _iph;
iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
if (!iph)
return -1;
/* Conntrack defragments packets, we might still see fragments
* inside ICMP packets though.
*/
if (iph->frag_off & htons(IP_OFFSET))
return -1;
dataoff = nhoff + (iph->ihl << 2);
*protonum = iph->protocol;
/* Check bogus IP headers */
if (dataoff > skb->len) {
pr_debug("bogus IPv4 packet: nhoff %u, ihl %u, skblen %u\n",
nhoff, iph->ihl << 2, skb->len);
return -1;
}
return dataoff;
}
#if IS_ENABLED(CONFIG_IPV6)
static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
u8 *protonum)
{
int protoff = -1;
unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
__be16 frag_off;
u8 nexthdr;
if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
&nexthdr, sizeof(nexthdr)) != 0) {
pr_debug("can't get nexthdr\n");
return -1;
}
protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
/*
* (protoff == skb->len) means the packet has not data, just
* IPv6 and possibly extensions headers, but it is tracked anyway
*/
if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
pr_debug("can't find proto in pkt\n");
return -1;
}
*protonum = nexthdr;
return protoff;
}
#endif
static int get_l4proto(const struct sk_buff *skb,
unsigned int nhoff, u8 pf, u8 *l4num)
{
switch (pf) {
case NFPROTO_IPV4:
return ipv4_get_l4proto(skb, nhoff, l4num);
#if IS_ENABLED(CONFIG_IPV6)
case NFPROTO_IPV6:
return ipv6_get_l4proto(skb, nhoff, l4num);
#endif
default:
*l4num = 0;
break;
}
return -1;
}
bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
u_int16_t l3num,
struct net *net, struct nf_conntrack_tuple *tuple)
{
u8 protonum;
int protoff;
protoff = get_l4proto(skb, nhoff, l3num, &protonum);
if (protoff <= 0)
return false;
return nf_ct_get_tuple(skb, nhoff, protoff, l3num, protonum, net, tuple);
}
EXPORT_SYMBOL_GPL(nf_ct_get_tuplepr);
bool
nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
const struct nf_conntrack_tuple *orig)
{
memset(inverse, 0, sizeof(*inverse));
inverse->src.l3num = orig->src.l3num;
switch (orig->src.l3num) {
case NFPROTO_IPV4:
inverse->src.u3.ip = orig->dst.u3.ip;
inverse->dst.u3.ip = orig->src.u3.ip;
break;
case NFPROTO_IPV6:
inverse->src.u3.in6 = orig->dst.u3.in6;
inverse->dst.u3.in6 = orig->src.u3.in6;
break;
default:
break;
}
inverse->dst.dir = !orig->dst.dir;
inverse->dst.protonum = orig->dst.protonum;
switch (orig->dst.protonum) {
case IPPROTO_ICMP:
return nf_conntrack_invert_icmp_tuple(inverse, orig);
#if IS_ENABLED(CONFIG_IPV6)
case IPPROTO_ICMPV6:
return nf_conntrack_invert_icmpv6_tuple(inverse, orig);
#endif
}
inverse->src.u.all = orig->dst.u.all;
inverse->dst.u.all = orig->src.u.all;
return true;
}
EXPORT_SYMBOL_GPL(nf_ct_invert_tuple);
/* Generate a almost-unique pseudo-id for a given conntrack.
*
* intentionally doesn't re-use any of the seeds used for hash
* table location, we assume id gets exposed to userspace.
*
* Following nf_conn items do not change throughout lifetime
* of the nf_conn:
*
* 1. nf_conn address
* 2. nf_conn->master address (normally NULL)
* 3. the associated net namespace
* 4. the original direction tuple
*/
u32 nf_ct_get_id(const struct nf_conn *ct)
{
static siphash_aligned_key_t ct_id_seed;
unsigned long a, b, c, d;
net_get_random_once(&ct_id_seed, sizeof(ct_id_seed));
a = (unsigned long)ct;
b = (unsigned long)ct->master;
c = (unsigned long)nf_ct_net(ct);
d = (unsigned long)siphash(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
sizeof(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple),
&ct_id_seed);
#ifdef CONFIG_64BIT
return siphash_4u64((u64)a, (u64)b, (u64)c, (u64)d, &ct_id_seed);
#else
return siphash_4u32((u32)a, (u32)b, (u32)c, (u32)d, &ct_id_seed);
#endif
}
EXPORT_SYMBOL_GPL(nf_ct_get_id);
static void
clean_from_lists(struct nf_conn *ct)
{
hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
/* Destroy all pending expectations */
nf_ct_remove_expectations(ct);
}
#define NFCT_ALIGN(len) (((len) + NFCT_INFOMASK) & ~NFCT_INFOMASK)
/* Released via nf_ct_destroy() */
struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
const struct nf_conntrack_zone *zone,
gfp_t flags)
{
struct nf_conn *tmpl, *p;
if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK) {
tmpl = kzalloc(sizeof(*tmpl) + NFCT_INFOMASK, flags);
if (!tmpl)
return NULL;
p = tmpl;
tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p);
if (tmpl != p) {
tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p);
tmpl->proto.tmpl_padto = (char *)tmpl - (char *)p;
}
} else {
tmpl = kzalloc(sizeof(*tmpl), flags);
if (!tmpl)
return NULL;
}
tmpl->status = IPS_TEMPLATE;
write_pnet(&tmpl->ct_net, net);
nf_ct_zone_add(tmpl, zone);
refcount_set(&tmpl->ct_general.use, 1);
return tmpl;
}
EXPORT_SYMBOL_GPL(nf_ct_tmpl_alloc);
void nf_ct_tmpl_free(struct nf_conn *tmpl)
{
kfree(tmpl->ext);
if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK)
kfree((char *)tmpl - tmpl->proto.tmpl_padto);
else
kfree(tmpl);
}
EXPORT_SYMBOL_GPL(nf_ct_tmpl_free);
static void destroy_gre_conntrack(struct nf_conn *ct)
{
#ifdef CONFIG_NF_CT_PROTO_GRE
struct nf_conn *master = ct->master;
if (master)
nf_ct_gre_keymap_destroy(master);
#endif
}
void nf_ct_destroy(struct nf_conntrack *nfct)
{
struct nf_conn *ct = (struct nf_conn *)nfct;
WARN_ON(refcount_read(&nfct->use) != 0);
if (unlikely(nf_ct_is_template(ct))) {
nf_ct_tmpl_free(ct);
return;
}
if (unlikely(nf_ct_protonum(ct) == IPPROTO_GRE))
destroy_gre_conntrack(ct);
/* Expectations will have been removed in clean_from_lists,
* except TFTP can create an expectation on the first packet,
* before connection is in the list, so we need to clean here,
* too.
*/
nf_ct_remove_expectations(ct);
if (ct->master)
nf_ct_put(ct->master);
nf_conntrack_free(ct);
}
EXPORT_SYMBOL(nf_ct_destroy);
static void __nf_ct_delete_from_lists(struct nf_conn *ct)
{
struct net *net = nf_ct_net(ct);
unsigned int hash, reply_hash;
unsigned int sequence;
do {
sequence = read_seqcount_begin(&nf_conntrack_generation);
hash = hash_conntrack(net,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_ORIGINAL));
reply_hash = hash_conntrack(net,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
clean_from_lists(ct);
nf_conntrack_double_unlock(hash, reply_hash);
}
static void nf_ct_delete_from_lists(struct nf_conn *ct)
{
nf_ct_helper_destroy(ct);
local_bh_disable();
__nf_ct_delete_from_lists(ct);
local_bh_enable();
}
static void nf_ct_add_to_ecache_list(struct nf_conn *ct)
{
#ifdef CONFIG_NF_CONNTRACK_EVENTS
struct nf_conntrack_net *cnet = nf_ct_pernet(nf_ct_net(ct));
spin_lock(&cnet->ecache.dying_lock);
hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
&cnet->ecache.dying_list);
spin_unlock(&cnet->ecache.dying_lock);
#endif
}
bool nf_ct_delete(struct nf_conn *ct, u32 portid, int report)
{
struct nf_conn_tstamp *tstamp;
struct net *net;
if (test_and_set_bit(IPS_DYING_BIT, &ct->status))
return false;
tstamp = nf_conn_tstamp_find(ct);
if (tstamp) {
s32 timeout = READ_ONCE(ct->timeout) - nfct_time_stamp;
tstamp->stop = ktime_get_real_ns();
if (timeout < 0)
tstamp->stop -= jiffies_to_nsecs(-timeout);
}
if (nf_conntrack_event_report(IPCT_DESTROY, ct,
portid, report) < 0) {
/* destroy event was not delivered. nf_ct_put will
* be done by event cache worker on redelivery.
*/
nf_ct_helper_destroy(ct);
local_bh_disable();
__nf_ct_delete_from_lists(ct);
nf_ct_add_to_ecache_list(ct);
local_bh_enable();
nf_conntrack_ecache_work(nf_ct_net(ct), NFCT_ECACHE_DESTROY_FAIL);
return false;
}
net = nf_ct_net(ct);
if (nf_conntrack_ecache_dwork_pending(net))
nf_conntrack_ecache_work(net, NFCT_ECACHE_DESTROY_SENT);
nf_ct_delete_from_lists(ct);
nf_ct_put(ct);
return true;
}
EXPORT_SYMBOL_GPL(nf_ct_delete);
static inline bool
nf_ct_key_equal(struct nf_conntrack_tuple_hash *h,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone,
const struct net *net)
{
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
/* A conntrack can be recreated with the equal tuple,
* so we need to check that the conntrack is confirmed
*/
return nf_ct_tuple_equal(tuple, &h->tuple) &&
nf_ct_zone_equal(ct, zone, NF_CT_DIRECTION(h)) &&
nf_ct_is_confirmed(ct) &&
net_eq(net, nf_ct_net(ct));
}
static inline bool
nf_ct_match(const struct nf_conn *ct1, const struct nf_conn *ct2)
{
return nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
&ct2->tuplehash[IP_CT_DIR_ORIGINAL].tuple) &&
nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_REPLY].tuple,
&ct2->tuplehash[IP_CT_DIR_REPLY].tuple) &&
nf_ct_zone_equal(ct1, nf_ct_zone(ct2), IP_CT_DIR_ORIGINAL) &&
nf_ct_zone_equal(ct1, nf_ct_zone(ct2), IP_CT_DIR_REPLY) &&
net_eq(nf_ct_net(ct1), nf_ct_net(ct2));
}
/* caller must hold rcu readlock and none of the nf_conntrack_locks */
static void nf_ct_gc_expired(struct nf_conn *ct)
{
if (!refcount_inc_not_zero(&ct->ct_general.use))
return;
/* load ->status after refcount increase */
smp_acquire__after_ctrl_dep();
if (nf_ct_should_gc(ct))
nf_ct_kill(ct);
nf_ct_put(ct);
}
/*
* Warning :
* - Caller must take a reference on returned object
* and recheck nf_ct_tuple_equal(tuple, &h->tuple)
*/
static struct nf_conntrack_tuple_hash *
____nf_conntrack_find(struct net *net, const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *tuple, u32 hash)
{
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_head *ct_hash;
struct hlist_nulls_node *n;
unsigned int bucket, hsize;
begin:
nf_conntrack_get_ht(&ct_hash, &hsize);
bucket = reciprocal_scale(hash, hsize);
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[bucket], hnnode) {
struct nf_conn *ct;
ct = nf_ct_tuplehash_to_ctrack(h);
if (nf_ct_is_expired(ct)) {
nf_ct_gc_expired(ct);
continue;
}
if (nf_ct_key_equal(h, tuple, zone, net))
return h;
}
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(n) != bucket) {
NF_CT_STAT_INC_ATOMIC(net, search_restart);
goto begin;
}
return NULL;
}
/* Find a connection corresponding to a tuple. */
static struct nf_conntrack_tuple_hash *
__nf_conntrack_find_get(struct net *net, const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *tuple, u32 hash)
{
struct nf_conntrack_tuple_hash *h;
struct nf_conn *ct;
h = ____nf_conntrack_find(net, zone, tuple, hash);
if (h) {
/* We have a candidate that matches the tuple we're interested
* in, try to obtain a reference and re-check tuple
*/
ct = nf_ct_tuplehash_to_ctrack(h);
if (likely(refcount_inc_not_zero(&ct->ct_general.use))) {
/* re-check key after refcount */
smp_acquire__after_ctrl_dep();
if (likely(nf_ct_key_equal(h, tuple, zone, net)))
return h;
/* TYPESAFE_BY_RCU recycled the candidate */
nf_ct_put(ct);
}
h = NULL;
}
return h;
}
struct nf_conntrack_tuple_hash *
nf_conntrack_find_get(struct net *net, const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *tuple)
{
unsigned int rid, zone_id = nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL);
struct nf_conntrack_tuple_hash *thash;
rcu_read_lock();
thash = __nf_conntrack_find_get(net, zone, tuple,
hash_conntrack_raw(tuple, zone_id, net));
if (thash)
goto out_unlock;
rid = nf_ct_zone_id(zone, IP_CT_DIR_REPLY);
if (rid != zone_id)
thash = __nf_conntrack_find_get(net, zone, tuple,
hash_conntrack_raw(tuple, rid, net));
out_unlock:
rcu_read_unlock();
return thash;
}
EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
static void __nf_conntrack_hash_insert(struct nf_conn *ct,
unsigned int hash,
unsigned int reply_hash)
{
hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
&nf_conntrack_hash[hash]);
hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode,
&nf_conntrack_hash[reply_hash]);
}
static bool nf_ct_ext_valid_pre(const struct nf_ct_ext *ext)
{
/* if ext->gen_id is not equal to nf_conntrack_ext_genid, some extensions
* may contain stale pointers to e.g. helper that has been removed.
*
* The helper can't clear this because the nf_conn object isn't in
* any hash and synchronize_rcu() isn't enough because associated skb
* might sit in a queue.
*/
return !ext || ext->gen_id == atomic_read(&nf_conntrack_ext_genid);
}
static bool nf_ct_ext_valid_post(struct nf_ct_ext *ext)
{
if (!ext)
return true;
if (ext->gen_id != atomic_read(&nf_conntrack_ext_genid))
return false;
/* inserted into conntrack table, nf_ct_iterate_cleanup()
* will find it. Disable nf_ct_ext_find() id check.
*/
WRITE_ONCE(ext->gen_id, 0);
return true;
}
int
nf_conntrack_hash_check_insert(struct nf_conn *ct)
{
const struct nf_conntrack_zone *zone;
struct net *net = nf_ct_net(ct);
unsigned int hash, reply_hash;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_node *n;
unsigned int max_chainlen;
unsigned int chainlen = 0;
unsigned int sequence;
int err = -EEXIST;
zone = nf_ct_zone(ct);
if (!nf_ct_ext_valid_pre(ct->ext))
return -EAGAIN;
local_bh_disable();
do {
sequence = read_seqcount_begin(&nf_conntrack_generation);
hash = hash_conntrack(net,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_ORIGINAL));
reply_hash = hash_conntrack(net,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
max_chainlen = MIN_CHAINLEN + get_random_u32_below(MAX_CHAINLEN);
/* See if there's one in the list already, including reverse */
hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) {
if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
zone, net))
goto out;
if (chainlen++ > max_chainlen)
goto chaintoolong;
}
chainlen = 0;
hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) {
if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
zone, net))
goto out;
if (chainlen++ > max_chainlen)
goto chaintoolong;
}
/* If genid has changed, we can't insert anymore because ct
* extensions could have stale pointers and nf_ct_iterate_destroy
* might have completed its table scan already.
*
* Increment of the ext genid right after this check is fine:
* nf_ct_iterate_destroy blocks until locks are released.
*/
if (!nf_ct_ext_valid_post(ct->ext)) {
err = -EAGAIN;
goto out;
}
smp_wmb();
/* The caller holds a reference to this object */
refcount_set(&ct->ct_general.use, 2);
__nf_conntrack_hash_insert(ct, hash, reply_hash);
nf_conntrack_double_unlock(hash, reply_hash);
NF_CT_STAT_INC(net, insert);
local_bh_enable();
return 0;
chaintoolong:
NF_CT_STAT_INC(net, chaintoolong);
err = -ENOSPC;
out:
nf_conntrack_double_unlock(hash, reply_hash);
local_bh_enable();
return err;
}
EXPORT_SYMBOL_GPL(nf_conntrack_hash_check_insert);
void nf_ct_acct_add(struct nf_conn *ct, u32 dir, unsigned int packets,
unsigned int bytes)
{
struct nf_conn_acct *acct;
acct = nf_conn_acct_find(ct);
if (acct) {
struct nf_conn_counter *counter = acct->counter;
atomic64_add(packets, &counter[dir].packets);
atomic64_add(bytes, &counter[dir].bytes);
}
}
EXPORT_SYMBOL_GPL(nf_ct_acct_add);
static void nf_ct_acct_merge(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
const struct nf_conn *loser_ct)
{
struct nf_conn_acct *acct;
acct = nf_conn_acct_find(loser_ct);
if (acct) {
struct nf_conn_counter *counter = acct->counter;
unsigned int bytes;
/* u32 should be fine since we must have seen one packet. */
bytes = atomic64_read(&counter[CTINFO2DIR(ctinfo)].bytes);
nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), bytes);
}
}
static void __nf_conntrack_insert_prepare(struct nf_conn *ct)
{
struct nf_conn_tstamp *tstamp;
refcount_inc(&ct->ct_general.use);
/* set conntrack timestamp, if enabled. */
tstamp = nf_conn_tstamp_find(ct);
if (tstamp)
tstamp->start = ktime_get_real_ns();
}
/**
* nf_ct_match_reverse - check if ct1 and ct2 refer to identical flow
* @ct1: conntrack in hash table to check against
* @ct2: merge candidate
*
* returns true if ct1 and ct2 happen to refer to the same flow, but
* in opposing directions, i.e.
* ct1: a:b -> c:d
* ct2: c:d -> a:b
* for both directions. If so, @ct2 should not have been created
* as the skb should have been picked up as ESTABLISHED flow.
* But ct1 was not yet committed to hash table before skb that created
* ct2 had arrived.
*
* Note we don't compare netns because ct entries in different net
* namespace cannot clash to begin with.
*
* @return: true if ct1 and ct2 are identical when swapping origin/reply.
*/
static bool
nf_ct_match_reverse(const struct nf_conn *ct1, const struct nf_conn *ct2)
{
u16 id1, id2;
if (!nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
&ct2->tuplehash[IP_CT_DIR_REPLY].tuple))
return false;
if (!nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_REPLY].tuple,
&ct2->tuplehash[IP_CT_DIR_ORIGINAL].tuple))
return false;
id1 = nf_ct_zone_id(nf_ct_zone(ct1), IP_CT_DIR_ORIGINAL);
id2 = nf_ct_zone_id(nf_ct_zone(ct2), IP_CT_DIR_REPLY);
if (id1 != id2)
return false;
id1 = nf_ct_zone_id(nf_ct_zone(ct1), IP_CT_DIR_REPLY);
id2 = nf_ct_zone_id(nf_ct_zone(ct2), IP_CT_DIR_ORIGINAL);
return id1 == id2;
}
static int nf_ct_can_merge(const struct nf_conn *ct,
const struct nf_conn *loser_ct)
{
return nf_ct_match(ct, loser_ct) ||
nf_ct_match_reverse(ct, loser_ct);
}
/* caller must hold locks to prevent concurrent changes */
static int __nf_ct_resolve_clash(struct sk_buff *skb,
struct nf_conntrack_tuple_hash *h)
{
/* This is the conntrack entry already in hashes that won race. */
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
enum ip_conntrack_info ctinfo;
struct nf_conn *loser_ct;
loser_ct = nf_ct_get(skb, &ctinfo);
if (nf_ct_can_merge(ct, loser_ct)) {
struct net *net = nf_ct_net(ct);
nf_conntrack_get(&ct->ct_general);
nf_ct_acct_merge(ct, ctinfo, loser_ct);
nf_ct_put(loser_ct);
nf_ct_set(skb, ct, ctinfo);
NF_CT_STAT_INC(net, clash_resolve);
return NF_ACCEPT;
}
return NF_DROP;
}
/**
* nf_ct_resolve_clash_harder - attempt to insert clashing conntrack entry
*
* @skb: skb that causes the collision
* @repl_idx: hash slot for reply direction
*
* Called when origin or reply direction had a clash.
* The skb can be handled without packet drop provided the reply direction
* is unique or there the existing entry has the identical tuple in both
* directions.
*
* Caller must hold conntrack table locks to prevent concurrent updates.
*
* Returns NF_DROP if the clash could not be handled.
*/
static int nf_ct_resolve_clash_harder(struct sk_buff *skb, u32 repl_idx)
{
struct nf_conn *loser_ct = (struct nf_conn *)skb_nfct(skb);
const struct nf_conntrack_zone *zone;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_node *n;
struct net *net;
zone = nf_ct_zone(loser_ct);
net = nf_ct_net(loser_ct);
/* Reply direction must never result in a clash, unless both origin
* and reply tuples are identical.
*/
hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[repl_idx], hnnode) {
if (nf_ct_key_equal(h,
&loser_ct->tuplehash[IP_CT_DIR_REPLY].tuple,
zone, net))
return __nf_ct_resolve_clash(skb, h);
}
/* We want the clashing entry to go away real soon: 1 second timeout. */
WRITE_ONCE(loser_ct->timeout, nfct_time_stamp + HZ);
/* IPS_NAT_CLASH removes the entry automatically on the first
* reply. Also prevents UDP tracker from moving the entry to
* ASSURED state, i.e. the entry can always be evicted under
* pressure.
*/
loser_ct->status |= IPS_FIXED_TIMEOUT | IPS_NAT_CLASH;
__nf_conntrack_insert_prepare(loser_ct);
/* fake add for ORIGINAL dir: we want lookups to only find the entry
* already in the table. This also hides the clashing entry from
* ctnetlink iteration, i.e. conntrack -L won't show them.
*/
hlist_nulls_add_fake(&loser_ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
hlist_nulls_add_head_rcu(&loser_ct->tuplehash[IP_CT_DIR_REPLY].hnnode,
&nf_conntrack_hash[repl_idx]);
NF_CT_STAT_INC(net, clash_resolve);
return NF_ACCEPT;
}
/**
* nf_ct_resolve_clash - attempt to handle clash without packet drop
*
* @skb: skb that causes the clash
* @h: tuplehash of the clashing entry already in table
* @reply_hash: hash slot for reply direction
*
* A conntrack entry can be inserted to the connection tracking table
* if there is no existing entry with an identical tuple.
*
* If there is one, @skb (and the associated, unconfirmed conntrack) has
* to be dropped. In case @skb is retransmitted, next conntrack lookup
* will find the already-existing entry.
*
* The major problem with such packet drop is the extra delay added by
* the packet loss -- it will take some time for a retransmit to occur
* (or the sender to time out when waiting for a reply).
*
* This function attempts to handle the situation without packet drop.
*
* If @skb has no NAT transformation or if the colliding entries are
* exactly the same, only the to-be-confirmed conntrack entry is discarded
* and @skb is associated with the conntrack entry already in the table.
*
* Failing that, the new, unconfirmed conntrack is still added to the table
* provided that the collision only occurs in the ORIGINAL direction.
* The new entry will be added only in the non-clashing REPLY direction,
* so packets in the ORIGINAL direction will continue to match the existing
* entry. The new entry will also have a fixed timeout so it expires --
* due to the collision, it will only see reply traffic.
*
* Returns NF_DROP if the clash could not be resolved.
*/
static __cold noinline int
nf_ct_resolve_clash(struct sk_buff *skb, struct nf_conntrack_tuple_hash *h,
u32 reply_hash)
{
/* This is the conntrack entry already in hashes that won race. */
struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
const struct nf_conntrack_l4proto *l4proto;
enum ip_conntrack_info ctinfo;
struct nf_conn *loser_ct;
struct net *net;
int ret;
loser_ct = nf_ct_get(skb, &ctinfo);
net = nf_ct_net(loser_ct);
l4proto = nf_ct_l4proto_find(nf_ct_protonum(ct));
if (!l4proto->allow_clash)
goto drop;
ret = __nf_ct_resolve_clash(skb, h);
if (ret == NF_ACCEPT)
return ret;
ret = nf_ct_resolve_clash_harder(skb, reply_hash);
if (ret == NF_ACCEPT)
return ret;
drop:
NF_CT_STAT_INC(net, drop);
NF_CT_STAT_INC(net, insert_failed);
return NF_DROP;
}
/* Confirm a connection given skb; places it in hash table */
int
__nf_conntrack_confirm(struct sk_buff *skb)
{
unsigned int chainlen = 0, sequence, max_chainlen;
const struct nf_conntrack_zone *zone;
unsigned int hash, reply_hash;
struct nf_conntrack_tuple_hash *h;
struct nf_conn *ct;
struct nf_conn_help *help;
struct hlist_nulls_node *n;
enum ip_conntrack_info ctinfo;
struct net *net;
int ret = NF_DROP;
ct = nf_ct_get(skb, &ctinfo);
net = nf_ct_net(ct);
/* ipt_REJECT uses nf_conntrack_attach to attach related
ICMP/TCP RST packets in other direction. Actual packet
which created connection will be IP_CT_NEW or for an
expected connection, IP_CT_RELATED. */
if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
return NF_ACCEPT;
zone = nf_ct_zone(ct);
local_bh_disable();
do {
sequence = read_seqcount_begin(&nf_conntrack_generation);
/* reuse the hash saved before */
hash = *(unsigned long *)&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev;
hash = scale_hash(hash);
reply_hash = hash_conntrack(net,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
/* We're not in hash table, and we refuse to set up related
* connections for unconfirmed conns. But packet copies and
* REJECT will give spurious warnings here.
*/
/* Another skb with the same unconfirmed conntrack may
* win the race. This may happen for bridge(br_flood)
* or broadcast/multicast packets do skb_clone with
* unconfirmed conntrack.
*/
if (unlikely(nf_ct_is_confirmed(ct))) {
WARN_ON_ONCE(1);
nf_conntrack_double_unlock(hash, reply_hash);
local_bh_enable();
return NF_DROP;
}
if (!nf_ct_ext_valid_pre(ct->ext)) {
NF_CT_STAT_INC(net, insert_failed);
goto dying;
}
/* We have to check the DYING flag after unlink to prevent
* a race against nf_ct_get_next_corpse() possibly called from
* user context, else we insert an already 'dead' hash, blocking
* further use of that particular connection -JM.
*/
ct->status |= IPS_CONFIRMED;
if (unlikely(nf_ct_is_dying(ct))) {
NF_CT_STAT_INC(net, insert_failed);
goto dying;
}
max_chainlen = MIN_CHAINLEN + get_random_u32_below(MAX_CHAINLEN);
/* See if there's one in the list already, including reverse:
NAT could have grabbed it without realizing, since we're
not in the hash. If there is, we lost race. */
hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) {
if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
zone, net))
goto out;
if (chainlen++ > max_chainlen)
goto chaintoolong;
}
chainlen = 0;
hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) {
if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
zone, net))
goto out;
if (chainlen++ > max_chainlen) {
chaintoolong:
NF_CT_STAT_INC(net, chaintoolong);
NF_CT_STAT_INC(net, insert_failed);
ret = NF_DROP;
goto dying;
}
}
/* Timer relative to confirmation time, not original
setting time, otherwise we'd get timer wrap in
weird delay cases. */
ct->timeout += nfct_time_stamp;
__nf_conntrack_insert_prepare(ct);
/* Since the lookup is lockless, hash insertion must be done after
* starting the timer and setting the CONFIRMED bit. The RCU barriers
* guarantee that no other CPU can find the conntrack before the above
* stores are visible.
*/
__nf_conntrack_hash_insert(ct, hash, reply_hash);
nf_conntrack_double_unlock(hash, reply_hash);
local_bh_enable();
/* ext area is still valid (rcu read lock is held,
* but will go out of scope soon, we need to remove
* this conntrack again.
*/
if (!nf_ct_ext_valid_post(ct->ext)) {
nf_ct_kill(ct);
NF_CT_STAT_INC_ATOMIC(net, drop);
return NF_DROP;
}
help = nfct_help(ct);
if (help && help->helper)
nf_conntrack_event_cache(IPCT_HELPER, ct);
nf_conntrack_event_cache(master_ct(ct) ?
IPCT_RELATED : IPCT_NEW, ct);
return NF_ACCEPT;
out:
ret = nf_ct_resolve_clash(skb, h, reply_hash);
dying:
nf_conntrack_double_unlock(hash, reply_hash);
local_bh_enable();
return ret;
}
EXPORT_SYMBOL_GPL(__nf_conntrack_confirm);
/* Returns true if a connection corresponds to the tuple (required
for NAT). */
int
nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
const struct nf_conn *ignored_conntrack)
{
struct net *net = nf_ct_net(ignored_conntrack);
const struct nf_conntrack_zone *zone;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_head *ct_hash;
unsigned int hash, hsize;
struct hlist_nulls_node *n;
struct nf_conn *ct;
zone = nf_ct_zone(ignored_conntrack);
rcu_read_lock();
begin:
nf_conntrack_get_ht(&ct_hash, &hsize);
hash = __hash_conntrack(net, tuple, nf_ct_zone_id(zone, IP_CT_DIR_REPLY), hsize);
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[hash], hnnode) {
ct = nf_ct_tuplehash_to_ctrack(h);
if (ct == ignored_conntrack)
continue;
if (nf_ct_is_expired(ct)) {
nf_ct_gc_expired(ct);
continue;
}
if (nf_ct_key_equal(h, tuple, zone, net)) {
/* Tuple is taken already, so caller will need to find
* a new source port to use.
*
* Only exception:
* If the *original tuples* are identical, then both
* conntracks refer to the same flow.
* This is a rare situation, it can occur e.g. when
* more than one UDP packet is sent from same socket
* in different threads.
*
* Let nf_ct_resolve_clash() deal with this later.
*/
if (nf_ct_tuple_equal(&ignored_conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple) &&
nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL))
continue;
NF_CT_STAT_INC_ATOMIC(net, found);
rcu_read_unlock();
return 1;
}
}
if (get_nulls_value(n) != hash) {
NF_CT_STAT_INC_ATOMIC(net, search_restart);
goto begin;
}
rcu_read_unlock();
return 0;
}
EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
#define NF_CT_EVICTION_RANGE 8
/* There's a small race here where we may free a just-assured
connection. Too bad: we're in trouble anyway. */
static unsigned int early_drop_list(struct net *net,
struct hlist_nulls_head *head)
{
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_node *n;
unsigned int drops = 0;
struct nf_conn *tmp;
hlist_nulls_for_each_entry_rcu(h, n, head, hnnode) {
tmp = nf_ct_tuplehash_to_ctrack(h);
if (nf_ct_is_expired(tmp)) {
nf_ct_gc_expired(tmp);
continue;
}
if (test_bit(IPS_ASSURED_BIT, &tmp->status) ||
!net_eq(nf_ct_net(tmp), net) ||
nf_ct_is_dying(tmp))
continue;
if (!refcount_inc_not_zero(&tmp->ct_general.use))
continue;
/* load ->ct_net and ->status after refcount increase */
smp_acquire__after_ctrl_dep();
/* kill only if still in same netns -- might have moved due to
* SLAB_TYPESAFE_BY_RCU rules.
*
* We steal the timer reference. If that fails timer has
* already fired or someone else deleted it. Just drop ref
* and move to next entry.
*/
if (net_eq(nf_ct_net(tmp), net) &&
nf_ct_is_confirmed(tmp) &&
nf_ct_delete(tmp, 0, 0))
drops++;
nf_ct_put(tmp);
}
return drops;
}
static noinline int early_drop(struct net *net, unsigned int hash)
{
unsigned int i, bucket;
for (i = 0; i < NF_CT_EVICTION_RANGE; i++) {
struct hlist_nulls_head *ct_hash;
unsigned int hsize, drops;
rcu_read_lock();
nf_conntrack_get_ht(&ct_hash, &hsize);
if (!i)
bucket = reciprocal_scale(hash, hsize);
else
bucket = (bucket + 1) % hsize;
drops = early_drop_list(net, &ct_hash[bucket]);
rcu_read_unlock();
if (drops) {
NF_CT_STAT_ADD_ATOMIC(net, early_drop, drops);
return true;
}
}
return false;
}
static bool gc_worker_skip_ct(const struct nf_conn *ct)
{
return !nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct);
}
static bool gc_worker_can_early_drop(const struct nf_conn *ct)
{
const struct nf_conntrack_l4proto *l4proto;
u8 protonum = nf_ct_protonum(ct);
if (!test_bit(IPS_ASSURED_BIT, &ct->status))
return true;
l4proto = nf_ct_l4proto_find(protonum);
if (l4proto->can_early_drop && l4proto->can_early_drop(ct))
return true;
return false;
}
static void gc_worker(struct work_struct *work)
{
unsigned int i, hashsz, nf_conntrack_max95 = 0;
u32 end_time, start_time = nfct_time_stamp;
struct conntrack_gc_work *gc_work;
unsigned int expired_count = 0;
unsigned long next_run;
s32 delta_time;
long count;
gc_work = container_of(work, struct conntrack_gc_work, dwork.work);
i = gc_work->next_bucket;
if (gc_work->early_drop)
nf_conntrack_max95 = nf_conntrack_max / 100u * 95u;
if (i == 0) {
gc_work->avg_timeout = GC_SCAN_INTERVAL_INIT;
gc_work->count = GC_SCAN_INITIAL_COUNT;
gc_work->start_time = start_time;
}
next_run = gc_work->avg_timeout;
count = gc_work->count;
end_time = start_time + GC_SCAN_MAX_DURATION;
do {
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_head *ct_hash;
struct hlist_nulls_node *n;
struct nf_conn *tmp;
rcu_read_lock();
nf_conntrack_get_ht(&ct_hash, &hashsz);
if (i >= hashsz) {
rcu_read_unlock();
break;
}
hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
struct nf_conntrack_net *cnet;
struct net *net;
long expires;
tmp = nf_ct_tuplehash_to_ctrack(h);
if (test_bit(IPS_OFFLOAD_BIT, &tmp->status)) {
nf_ct_offload_timeout(tmp);
if (!nf_conntrack_max95)
continue;
}
if (expired_count > GC_SCAN_EXPIRED_MAX) {
rcu_read_unlock();
gc_work->next_bucket = i;
gc_work->avg_timeout = next_run;
gc_work->count = count;
delta_time = nfct_time_stamp - gc_work->start_time;
/* re-sched immediately if total cycle time is exceeded */
next_run = delta_time < (s32)GC_SCAN_INTERVAL_MAX;
goto early_exit;
}
if (nf_ct_is_expired(tmp)) {
nf_ct_gc_expired(tmp);
expired_count++;
continue;
}
expires = clamp(nf_ct_expires(tmp), GC_SCAN_INTERVAL_MIN, GC_SCAN_INTERVAL_CLAMP);
expires = (expires - (long)next_run) / ++count;
next_run += expires;
if (nf_conntrack_max95 == 0 || gc_worker_skip_ct(tmp))
continue;
net = nf_ct_net(tmp);
cnet = nf_ct_pernet(net);
if (atomic_read(&cnet->count) < nf_conntrack_max95)
continue;
/* need to take reference to avoid possible races */
if (!refcount_inc_not_zero(&tmp->ct_general.use))
continue;
/* load ->status after refcount increase */
smp_acquire__after_ctrl_dep();
if (gc_worker_skip_ct(tmp)) {
nf_ct_put(tmp);
continue;
}
if (gc_worker_can_early_drop(tmp)) {
nf_ct_kill(tmp);
expired_count++;
}
nf_ct_put(tmp);
}
/* could check get_nulls_value() here and restart if ct
* was moved to another chain. But given gc is best-effort
* we will just continue with next hash slot.
*/
rcu_read_unlock();
cond_resched();
i++;
delta_time = nfct_time_stamp - end_time;
if (delta_time > 0 && i < hashsz) {
gc_work->avg_timeout = next_run;
gc_work->count = count;
gc_work->next_bucket = i;
next_run = 0;
goto early_exit;
}
} while (i < hashsz);
gc_work->next_bucket = 0;
next_run = clamp(next_run, GC_SCAN_INTERVAL_MIN, GC_SCAN_INTERVAL_MAX);
delta_time = max_t(s32, nfct_time_stamp - gc_work->start_time, 1);
if (next_run > (unsigned long)delta_time)
next_run -= delta_time;
else
next_run = 1;
early_exit:
if (gc_work->exiting)
return;
if (next_run)
gc_work->early_drop = false;
queue_delayed_work(system_power_efficient_wq, &gc_work->dwork, next_run);
}
static void conntrack_gc_work_init(struct conntrack_gc_work *gc_work)
{
INIT_DELAYED_WORK(&gc_work->dwork, gc_worker);
gc_work->exiting = false;
}
static struct nf_conn *
__nf_conntrack_alloc(struct net *net,
const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *orig,
const struct nf_conntrack_tuple *repl,
gfp_t gfp, u32 hash)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
unsigned int ct_count;
struct nf_conn *ct;
/* We don't want any race condition at early drop stage */
ct_count = atomic_inc_return(&cnet->count);
if (nf_conntrack_max && unlikely(ct_count > nf_conntrack_max)) {
if (!early_drop(net, hash)) {
if (!conntrack_gc_work.early_drop)
conntrack_gc_work.early_drop = true;
atomic_dec(&cnet->count);
net_warn_ratelimited("nf_conntrack: table full, dropping packet\n");
return ERR_PTR(-ENOMEM);
}
}
/*
* Do not use kmem_cache_zalloc(), as this cache uses
* SLAB_TYPESAFE_BY_RCU.
*/
ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
if (ct == NULL)
goto out;
spin_lock_init(&ct->lock);
ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL;
ct->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
/* save hash for reusing when confirming */
*(unsigned long *)(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev) = hash;
ct->status = 0;
WRITE_ONCE(ct->timeout, 0);
write_pnet(&ct->ct_net, net);
memset_after(ct, 0, __nfct_init_offset);
nf_ct_zone_add(ct, zone);
/* Because we use RCU lookups, we set ct_general.use to zero before
* this is inserted in any list.
*/
refcount_set(&ct->ct_general.use, 0);
return ct;
out:
atomic_dec(&cnet->count);
return ERR_PTR(-ENOMEM);
}
struct nf_conn *nf_conntrack_alloc(struct net *net,
const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *orig,
const struct nf_conntrack_tuple *repl,
gfp_t gfp)
{
return __nf_conntrack_alloc(net, zone, orig, repl, gfp, 0);
}
EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
void nf_conntrack_free(struct nf_conn *ct)
{
struct net *net = nf_ct_net(ct);
struct nf_conntrack_net *cnet;
/* A freed object has refcnt == 0, that's
* the golden rule for SLAB_TYPESAFE_BY_RCU
*/
WARN_ON(refcount_read(&ct->ct_general.use) != 0);
if (ct->status & IPS_SRC_NAT_DONE) {
const struct nf_nat_hook *nat_hook;
rcu_read_lock();
nat_hook = rcu_dereference(nf_nat_hook);
if (nat_hook)
nat_hook->remove_nat_bysrc(ct);
rcu_read_unlock();
}
kfree(ct->ext);
kmem_cache_free(nf_conntrack_cachep, ct);
cnet = nf_ct_pernet(net);
smp_mb__before_atomic();
atomic_dec(&cnet->count);
}
EXPORT_SYMBOL_GPL(nf_conntrack_free);
/* Allocate a new conntrack: we return -ENOMEM if classification
failed due to stress. Otherwise it really is unclassifiable. */
static noinline struct nf_conntrack_tuple_hash *
init_conntrack(struct net *net, struct nf_conn *tmpl,
const struct nf_conntrack_tuple *tuple,
struct sk_buff *skb,
unsigned int dataoff, u32 hash)
{
struct nf_conn *ct;
struct nf_conn_help *help;
struct nf_conntrack_tuple repl_tuple;
#ifdef CONFIG_NF_CONNTRACK_EVENTS
struct nf_conntrack_ecache *ecache;
#endif
struct nf_conntrack_expect *exp = NULL;
const struct nf_conntrack_zone *zone;
struct nf_conn_timeout *timeout_ext;
struct nf_conntrack_zone tmp;
struct nf_conntrack_net *cnet;
if (!nf_ct_invert_tuple(&repl_tuple, tuple))
return NULL;
zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
ct = __nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC,
hash);
if (IS_ERR(ct))
return ERR_CAST(ct);
if (!nf_ct_add_synproxy(ct, tmpl)) {
nf_conntrack_free(ct);
return ERR_PTR(-ENOMEM);
}
timeout_ext = tmpl ? nf_ct_timeout_find(tmpl) : NULL;
if (timeout_ext)
nf_ct_timeout_ext_add(ct, rcu_dereference(timeout_ext->timeout),
GFP_ATOMIC);
nf_ct_acct_ext_add(ct, GFP_ATOMIC);
nf_ct_tstamp_ext_add(ct, GFP_ATOMIC);
nf_ct_labels_ext_add(ct);
#ifdef CONFIG_NF_CONNTRACK_EVENTS
ecache = tmpl ? nf_ct_ecache_find(tmpl) : NULL;
if ((ecache || net->ct.sysctl_events) &&
!nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,
ecache ? ecache->expmask : 0,
GFP_ATOMIC)) {
nf_conntrack_free(ct);
return ERR_PTR(-ENOMEM);
}
#endif
cnet = nf_ct_pernet(net);
if (cnet->expect_count) {
spin_lock_bh(&nf_conntrack_expect_lock);
exp = nf_ct_find_expectation(net, zone, tuple, !tmpl || nf_ct_is_confirmed(tmpl));
if (exp) {
/* Welcome, Mr. Bond. We've been expecting you... */
__set_bit(IPS_EXPECTED_BIT, &ct->status);
/* exp->master safe, refcnt bumped in nf_ct_find_expectation */
ct->master = exp->master;
if (exp->helper) {
help = nf_ct_helper_ext_add(ct, GFP_ATOMIC);
if (help)
rcu_assign_pointer(help->helper, exp->helper);
}
#ifdef CONFIG_NF_CONNTRACK_MARK
ct->mark = READ_ONCE(exp->master->mark);
#endif
#ifdef CONFIG_NF_CONNTRACK_SECMARK
ct->secmark = exp->master->secmark;
#endif
NF_CT_STAT_INC(net, expect_new);
}
spin_unlock_bh(&nf_conntrack_expect_lock);
}
if (!exp && tmpl)
__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
/* Other CPU might have obtained a pointer to this object before it was
* released. Because refcount is 0, refcount_inc_not_zero() will fail.
*
* After refcount_set(1) it will succeed; ensure that zeroing of
* ct->status and the correct ct->net pointer are visible; else other
* core might observe CONFIRMED bit which means the entry is valid and
* in the hash table, but its not (anymore).
*/
smp_wmb();
/* Now it is going to be associated with an sk_buff, set refcount to 1. */
refcount_set(&ct->ct_general.use, 1);
if (exp) {
if (exp->expectfn)
exp->expectfn(ct, exp);
nf_ct_expect_put(exp);
}
return &ct->tuplehash[IP_CT_DIR_ORIGINAL];
}
/* On success, returns 0, sets skb->_nfct | ctinfo */
static int
resolve_normal_ct(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
u_int8_t protonum,
const struct nf_hook_state *state)
{
const struct nf_conntrack_zone *zone;
struct nf_conntrack_tuple tuple;
struct nf_conntrack_tuple_hash *h;
enum ip_conntrack_info ctinfo;
struct nf_conntrack_zone tmp;
u32 hash, zone_id, rid;
struct nf_conn *ct;
if (!nf_ct_get_tuple(skb, skb_network_offset(skb),
dataoff, state->pf, protonum, state->net,
&tuple))
return 0;
/* look for tuple match */
zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
zone_id = nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL);
hash = hash_conntrack_raw(&tuple, zone_id, state->net);
h = __nf_conntrack_find_get(state->net, zone, &tuple, hash);
if (!h) {
rid = nf_ct_zone_id(zone, IP_CT_DIR_REPLY);
if (zone_id != rid) {
u32 tmp = hash_conntrack_raw(&tuple, rid, state->net);
h = __nf_conntrack_find_get(state->net, zone, &tuple, tmp);
}
}
if (!h) {
h = init_conntrack(state->net, tmpl, &tuple,
skb, dataoff, hash);
if (!h)
return 0;
if (IS_ERR(h))
return PTR_ERR(h);
}
ct = nf_ct_tuplehash_to_ctrack(h);
/* It exists; we have (non-exclusive) reference. */
if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) {
ctinfo = IP_CT_ESTABLISHED_REPLY;
} else {
unsigned long status = READ_ONCE(ct->status);
/* Once we've had two way comms, always ESTABLISHED. */
if (likely(status & IPS_SEEN_REPLY))
ctinfo = IP_CT_ESTABLISHED;
else if (status & IPS_EXPECTED)
ctinfo = IP_CT_RELATED;
else
ctinfo = IP_CT_NEW;
}
nf_ct_set(skb, ct, ctinfo);
return 0;
}
/*
* icmp packets need special treatment to handle error messages that are
* related to a connection.
*
* Callers need to check if skb has a conntrack assigned when this
* helper returns; in such case skb belongs to an already known connection.
*/
static unsigned int __cold
nf_conntrack_handle_icmp(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
u8 protonum,
const struct nf_hook_state *state)
{
int ret;
if (state->pf == NFPROTO_IPV4 && protonum == IPPROTO_ICMP)
ret = nf_conntrack_icmpv4_error(tmpl, skb, dataoff, state);
#if IS_ENABLED(CONFIG_IPV6)
else if (state->pf == NFPROTO_IPV6 && protonum == IPPROTO_ICMPV6)
ret = nf_conntrack_icmpv6_error(tmpl, skb, dataoff, state);
#endif
else
return NF_ACCEPT;
if (ret <= 0)
NF_CT_STAT_INC_ATOMIC(state->net, error);
return ret;
}
static int generic_packet(struct nf_conn *ct, struct sk_buff *skb,
enum ip_conntrack_info ctinfo)
{
const unsigned int *timeout = nf_ct_timeout_lookup(ct);
if (!timeout)
timeout = &nf_generic_pernet(nf_ct_net(ct))->timeout;
nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
return NF_ACCEPT;
}
/* Returns verdict for packet, or -1 for invalid. */
static int nf_conntrack_handle_packet(struct nf_conn *ct,
struct sk_buff *skb,
unsigned int dataoff,
enum ip_conntrack_info ctinfo,
const struct nf_hook_state *state)
{
switch (nf_ct_protonum(ct)) {
case IPPROTO_TCP:
return nf_conntrack_tcp_packet(ct, skb, dataoff,
ctinfo, state);
case IPPROTO_UDP:
return nf_conntrack_udp_packet(ct, skb, dataoff,
ctinfo, state);
case IPPROTO_ICMP:
return nf_conntrack_icmp_packet(ct, skb, ctinfo, state);
#if IS_ENABLED(CONFIG_IPV6)
case IPPROTO_ICMPV6:
return nf_conntrack_icmpv6_packet(ct, skb, ctinfo, state);
#endif
#ifdef CONFIG_NF_CT_PROTO_UDPLITE
case IPPROTO_UDPLITE:
return nf_conntrack_udplite_packet(ct, skb, dataoff,
ctinfo, state);
#endif
#ifdef CONFIG_NF_CT_PROTO_SCTP
case IPPROTO_SCTP:
return nf_conntrack_sctp_packet(ct, skb, dataoff,
ctinfo, state);
#endif
#ifdef CONFIG_NF_CT_PROTO_DCCP
case IPPROTO_DCCP:
return nf_conntrack_dccp_packet(ct, skb, dataoff,
ctinfo, state);
#endif
#ifdef CONFIG_NF_CT_PROTO_GRE
case IPPROTO_GRE:
return nf_conntrack_gre_packet(ct, skb, dataoff,
ctinfo, state);
#endif
}
return generic_packet(ct, skb, ctinfo);
}
unsigned int
nf_conntrack_in(struct sk_buff *skb, const struct nf_hook_state *state)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct, *tmpl;
u_int8_t protonum;
int dataoff, ret;
tmpl = nf_ct_get(skb, &ctinfo);
if (tmpl || ctinfo == IP_CT_UNTRACKED) {
/* Previously seen (loopback or untracked)? Ignore. */
if ((tmpl && !nf_ct_is_template(tmpl)) ||
ctinfo == IP_CT_UNTRACKED)
return NF_ACCEPT;
skb->_nfct = 0;
}
/* rcu_read_lock()ed by nf_hook_thresh */
dataoff = get_l4proto(skb, skb_network_offset(skb), state->pf, &protonum);
if (dataoff <= 0) {
NF_CT_STAT_INC_ATOMIC(state->net, invalid);
ret = NF_ACCEPT;
goto out;
}
if (protonum == IPPROTO_ICMP || protonum == IPPROTO_ICMPV6) {
ret = nf_conntrack_handle_icmp(tmpl, skb, dataoff,
protonum, state);
if (ret <= 0) {
ret = -ret;
goto out;
}
/* ICMP[v6] protocol trackers may assign one conntrack. */
if (skb->_nfct)
goto out;
}
repeat:
ret = resolve_normal_ct(tmpl, skb, dataoff,
protonum, state);
if (ret < 0) {
/* Too stressed to deal. */
NF_CT_STAT_INC_ATOMIC(state->net, drop);
ret = NF_DROP;
goto out;
}
ct = nf_ct_get(skb, &ctinfo);
if (!ct) {
/* Not valid part of a connection */
NF_CT_STAT_INC_ATOMIC(state->net, invalid);
ret = NF_ACCEPT;
goto out;
}
ret = nf_conntrack_handle_packet(ct, skb, dataoff, ctinfo, state);
if (ret <= 0) {
/* Invalid: inverse of the return code tells
* the netfilter core what to do */
nf_ct_put(ct);
skb->_nfct = 0;
/* Special case: TCP tracker reports an attempt to reopen a
* closed/aborted connection. We have to go back and create a
* fresh conntrack.
*/
if (ret == -NF_REPEAT)
goto repeat;
NF_CT_STAT_INC_ATOMIC(state->net, invalid);
if (ret == NF_DROP)
NF_CT_STAT_INC_ATOMIC(state->net, drop);
ret = -ret;
goto out;
}
if (ctinfo == IP_CT_ESTABLISHED_REPLY &&
!test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
nf_conntrack_event_cache(IPCT_REPLY, ct);
out:
if (tmpl)
nf_ct_put(tmpl);
return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_in);
/* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
void __nf_ct_refresh_acct(struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
const struct sk_buff *skb,
u32 extra_jiffies,
bool do_acct)
{
/* Only update if this is not a fixed timeout */
if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
goto acct;
/* If not in hash table, timer will not be active yet */
if (nf_ct_is_confirmed(ct))
extra_jiffies += nfct_time_stamp;
if (READ_ONCE(ct->timeout) != extra_jiffies)
WRITE_ONCE(ct->timeout, extra_jiffies);
acct:
if (do_acct)
nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
}
EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
bool nf_ct_kill_acct(struct nf_conn *ct,
enum ip_conntrack_info ctinfo,
const struct sk_buff *skb)
{
nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
return nf_ct_delete(ct, 0, 0);
}
EXPORT_SYMBOL_GPL(nf_ct_kill_acct);
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
#include <linux/mutex.h>
/* Generic function for tcp/udp/sctp/dccp and alike. */
int nf_ct_port_tuple_to_nlattr(struct sk_buff *skb,
const struct nf_conntrack_tuple *tuple)
{
if (nla_put_be16(skb, CTA_PROTO_SRC_PORT, tuple->src.u.tcp.port) ||
nla_put_be16(skb, CTA_PROTO_DST_PORT, tuple->dst.u.tcp.port))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nlattr);
const struct nla_policy nf_ct_port_nla_policy[CTA_PROTO_MAX+1] = {
[CTA_PROTO_SRC_PORT] = { .type = NLA_U16 },
[CTA_PROTO_DST_PORT] = { .type = NLA_U16 },
};
EXPORT_SYMBOL_GPL(nf_ct_port_nla_policy);
int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[],
struct nf_conntrack_tuple *t,
u_int32_t flags)
{
if (flags & CTA_FILTER_FLAG(CTA_PROTO_SRC_PORT)) {
if (!tb[CTA_PROTO_SRC_PORT])
return -EINVAL;
t->src.u.tcp.port = nla_get_be16(tb[CTA_PROTO_SRC_PORT]);
}
if (flags & CTA_FILTER_FLAG(CTA_PROTO_DST_PORT)) {
if (!tb[CTA_PROTO_DST_PORT])
return -EINVAL;
t->dst.u.tcp.port = nla_get_be16(tb[CTA_PROTO_DST_PORT]);
}
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_to_tuple);
unsigned int nf_ct_port_nlattr_tuple_size(void)
{
static unsigned int size __read_mostly;
if (!size)
size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
return size;
}
EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_tuple_size);
#endif
/* Used by ipt_REJECT and ip6t_REJECT. */
static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
/* This ICMP is in reverse direction to the packet which caused it */
ct = nf_ct_get(skb, &ctinfo);
if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
ctinfo = IP_CT_RELATED_REPLY;
else
ctinfo = IP_CT_RELATED;
/* Attach to new skbuff, and increment count */
nf_ct_set(nskb, ct, ctinfo);
nf_conntrack_get(skb_nfct(nskb));
}
/* This packet is coming from userspace via nf_queue, complete the packet
* processing after the helper invocation in nf_confirm().
*/
static int nf_confirm_cthelper(struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo)
{
const struct nf_conntrack_helper *helper;
const struct nf_conn_help *help;
int protoff;
help = nfct_help(ct);
if (!help)
return NF_ACCEPT;
helper = rcu_dereference(help->helper);
if (!helper)
return NF_ACCEPT;
if (!(helper->flags & NF_CT_HELPER_F_USERSPACE))
return NF_ACCEPT;
switch (nf_ct_l3num(ct)) {
case NFPROTO_IPV4:
protoff = skb_network_offset(skb) + ip_hdrlen(skb);
break;
#if IS_ENABLED(CONFIG_IPV6)
case NFPROTO_IPV6: {
__be16 frag_off;
u8 pnum;
pnum = ipv6_hdr(skb)->nexthdr;
protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
&frag_off);
if (protoff < 0 || (frag_off & htons(~0x7)) != 0)
return NF_ACCEPT;
break;
}
#endif
default:
return NF_ACCEPT;
}
if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
!nf_is_loopback_packet(skb)) {
if (!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
return NF_DROP;
}
}
/* We've seen it coming out the other side: confirm it */
return nf_conntrack_confirm(skb);
}
static int nf_conntrack_update(struct net *net, struct sk_buff *skb)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
ct = nf_ct_get(skb, &ctinfo);
if (!ct)
return NF_ACCEPT;
return nf_confirm_cthelper(skb, ct, ctinfo);
}
static bool nf_conntrack_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
const struct sk_buff *skb)
{
const struct nf_conntrack_tuple *src_tuple;
const struct nf_conntrack_tuple_hash *hash;
struct nf_conntrack_tuple srctuple;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
ct = nf_ct_get(skb, &ctinfo);
if (ct) {
src_tuple = nf_ct_tuple(ct, CTINFO2DIR(ctinfo));
memcpy(dst_tuple, src_tuple, sizeof(*dst_tuple));
return true;
}
if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
NFPROTO_IPV4, dev_net(skb->dev),
&srctuple))
return false;
hash = nf_conntrack_find_get(dev_net(skb->dev),
&nf_ct_zone_dflt,
&srctuple);
if (!hash)
return false;
ct = nf_ct_tuplehash_to_ctrack(hash);
src_tuple = nf_ct_tuple(ct, !hash->tuple.dst.dir);
memcpy(dst_tuple, src_tuple, sizeof(*dst_tuple));
nf_ct_put(ct);
return true;
}
/* Bring out ya dead! */
static struct nf_conn *
get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
const struct nf_ct_iter_data *iter_data, unsigned int *bucket)
{
struct nf_conntrack_tuple_hash *h;
struct nf_conn *ct;
struct hlist_nulls_node *n;
spinlock_t *lockp;
for (; *bucket < nf_conntrack_htable_size; (*bucket)++) {
struct hlist_nulls_head *hslot = &nf_conntrack_hash[*bucket];
if (hlist_nulls_empty(hslot))
continue;
lockp = &nf_conntrack_locks[*bucket % CONNTRACK_LOCKS];
local_bh_disable();
nf_conntrack_lock(lockp);
hlist_nulls_for_each_entry(h, n, hslot, hnnode) {
if (NF_CT_DIRECTION(h) != IP_CT_DIR_REPLY)
continue;
/* All nf_conn objects are added to hash table twice, one
* for original direction tuple, once for the reply tuple.
*
* Exception: In the IPS_NAT_CLASH case, only the reply
* tuple is added (the original tuple already existed for
* a different object).
*
* We only need to call the iterator once for each
* conntrack, so we just use the 'reply' direction
* tuple while iterating.
*/
ct = nf_ct_tuplehash_to_ctrack(h);
if (iter_data->net &&
!net_eq(iter_data->net, nf_ct_net(ct)))
continue;
if (iter(ct, iter_data->data))
goto found;
}
spin_unlock(lockp);
local_bh_enable();
cond_resched();
}
return NULL;
found:
refcount_inc(&ct->ct_general.use);
spin_unlock(lockp);
local_bh_enable();
return ct;
}
static void nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data),
const struct nf_ct_iter_data *iter_data)
{
unsigned int bucket = 0;
struct nf_conn *ct;
might_sleep();
mutex_lock(&nf_conntrack_mutex);
while ((ct = get_next_corpse(iter, iter_data, &bucket)) != NULL) {
/* Time to push up daises... */
nf_ct_delete(ct, iter_data->portid, iter_data->report);
nf_ct_put(ct);
cond_resched();
}
mutex_unlock(&nf_conntrack_mutex);
}
void nf_ct_iterate_cleanup_net(int (*iter)(struct nf_conn *i, void *data),
const struct nf_ct_iter_data *iter_data)
{
struct net *net = iter_data->net;
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
might_sleep();
if (atomic_read(&cnet->count) == 0)
return;
nf_ct_iterate_cleanup(iter, iter_data);
}
EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup_net);
/**
* nf_ct_iterate_destroy - destroy unconfirmed conntracks and iterate table
* @iter: callback to invoke for each conntrack
* @data: data to pass to @iter
*
* Like nf_ct_iterate_cleanup, but first marks conntracks on the
* unconfirmed list as dying (so they will not be inserted into
* main table).
*
* Can only be called in module exit path.
*/
void
nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
{
struct nf_ct_iter_data iter_data = {};
struct net *net;
down_read(&net_rwsem);
for_each_net(net) {
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
if (atomic_read(&cnet->count) == 0)
continue;
nf_queue_nf_hook_drop(net);
}
up_read(&net_rwsem);
/* Need to wait for netns cleanup worker to finish, if its
* running -- it might have deleted a net namespace from
* the global list, so hook drop above might not have
* affected all namespaces.
*/
net_ns_barrier();
/* a skb w. unconfirmed conntrack could have been reinjected just
* before we called nf_queue_nf_hook_drop().
*
* This makes sure its inserted into conntrack table.
*/
synchronize_net();
nf_ct_ext_bump_genid();
iter_data.data = data;
nf_ct_iterate_cleanup(iter, &iter_data);
/* Another cpu might be in a rcu read section with
* rcu protected pointer cleared in iter callback
* or hidden via nf_ct_ext_bump_genid() above.
*
* Wait until those are done.
*/
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_ct_iterate_destroy);
static int kill_all(struct nf_conn *i, void *data)
{
return 1;
}
void nf_conntrack_cleanup_start(void)
{
cleanup_nf_conntrack_bpf();
conntrack_gc_work.exiting = true;
}
void nf_conntrack_cleanup_end(void)
{
RCU_INIT_POINTER(nf_ct_hook, NULL);
cancel_delayed_work_sync(&conntrack_gc_work.dwork);
kvfree(nf_conntrack_hash);
nf_conntrack_proto_fini();
nf_conntrack_helper_fini();
nf_conntrack_expect_fini();
kmem_cache_destroy(nf_conntrack_cachep);
}
/*
* Mishearing the voices in his head, our hero wonders how he's
* supposed to kill the mall.
*/
void nf_conntrack_cleanup_net(struct net *net)
{
LIST_HEAD(single);
list_add(&net->exit_list, &single);
nf_conntrack_cleanup_net_list(&single);
}
void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
{
struct nf_ct_iter_data iter_data = {};
struct net *net;
int busy;
/*
* This makes sure all current packets have passed through
* netfilter framework. Roll on, two-stage module
* delete...
*/
synchronize_rcu_expedited();
i_see_dead_people:
busy = 0;
list_for_each_entry(net, net_exit_list, exit_list) {
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
iter_data.net = net;
nf_ct_iterate_cleanup_net(kill_all, &iter_data);
if (atomic_read(&cnet->count) != 0)
busy = 1;
}
if (busy) {
schedule();
goto i_see_dead_people;
}
list_for_each_entry(net, net_exit_list, exit_list) {
nf_conntrack_ecache_pernet_fini(net);
nf_conntrack_expect_pernet_fini(net);
free_percpu(net->ct.stat);
}
}
void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
{
struct hlist_nulls_head *hash;
unsigned int nr_slots, i;
if (*sizep > (UINT_MAX / sizeof(struct hlist_nulls_head)))
return NULL;
BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL);
if (hash && nulls)
for (i = 0; i < nr_slots; i++)
INIT_HLIST_NULLS_HEAD(&hash[i], i);
return hash;
}
EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable);
int nf_conntrack_hash_resize(unsigned int hashsize)
{
int i, bucket;
unsigned int old_size;
struct hlist_nulls_head *hash, *old_hash;
struct nf_conntrack_tuple_hash *h;
struct nf_conn *ct;
if (!hashsize)
return -EINVAL;
hash = nf_ct_alloc_hashtable(&hashsize, 1);
if (!hash)
return -ENOMEM;
mutex_lock(&nf_conntrack_mutex);
old_size = nf_conntrack_htable_size;
if (old_size == hashsize) {
mutex_unlock(&nf_conntrack_mutex);
kvfree(hash);
return 0;
}
local_bh_disable();
nf_conntrack_all_lock();
write_seqcount_begin(&nf_conntrack_generation);
/* Lookups in the old hash might happen in parallel, which means we
* might get false negatives during connection lookup. New connections
* created because of a false negative won't make it into the hash
* though since that required taking the locks.
*/
for (i = 0; i < nf_conntrack_htable_size; i++) {
while (!hlist_nulls_empty(&nf_conntrack_hash[i])) {
unsigned int zone_id;
h = hlist_nulls_entry(nf_conntrack_hash[i].first,
struct nf_conntrack_tuple_hash, hnnode);
ct = nf_ct_tuplehash_to_ctrack(h);
hlist_nulls_del_rcu(&h->hnnode);
zone_id = nf_ct_zone_id(nf_ct_zone(ct), NF_CT_DIRECTION(h));
bucket = __hash_conntrack(nf_ct_net(ct),
&h->tuple, zone_id, hashsize);
hlist_nulls_add_head_rcu(&h->hnnode, &hash[bucket]);
}
}
old_hash = nf_conntrack_hash;
nf_conntrack_hash = hash;
nf_conntrack_htable_size = hashsize;
write_seqcount_end(&nf_conntrack_generation);
nf_conntrack_all_unlock();
local_bh_enable();
mutex_unlock(&nf_conntrack_mutex);
synchronize_net();
kvfree(old_hash);
return 0;
}
int nf_conntrack_set_hashsize(const char *val, const struct kernel_param *kp)
{
unsigned int hashsize;
int rc;
if (current->nsproxy->net_ns != &init_net)
return -EOPNOTSUPP;
/* On boot, we can set this without any fancy locking. */
if (!nf_conntrack_hash)
return param_set_uint(val, kp);
rc = kstrtouint(val, 0, &hashsize);
if (rc)
return rc;
return nf_conntrack_hash_resize(hashsize);
}
int nf_conntrack_init_start(void)
{
unsigned long nr_pages = totalram_pages();
int max_factor = 8;
int ret = -ENOMEM;
int i;
seqcount_spinlock_init(&nf_conntrack_generation,
&nf_conntrack_locks_all_lock);
for (i = 0; i < CONNTRACK_LOCKS; i++)
spin_lock_init(&nf_conntrack_locks[i]);
if (!nf_conntrack_htable_size) {
nf_conntrack_htable_size
= (((nr_pages << PAGE_SHIFT) / 16384)
/ sizeof(struct hlist_head));
if (BITS_PER_LONG >= 64 &&
nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
nf_conntrack_htable_size = 262144;
else if (nr_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
nf_conntrack_htable_size = 65536;
if (nf_conntrack_htable_size < 1024)
nf_conntrack_htable_size = 1024;
/* Use a max. factor of one by default to keep the average
* hash chain length at 2 entries. Each entry has to be added
* twice (once for original direction, once for reply).
* When a table size is given we use the old value of 8 to
* avoid implicit reduction of the max entries setting.
*/
max_factor = 1;
}
nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1);
if (!nf_conntrack_hash)
return -ENOMEM;
nf_conntrack_max = max_factor * nf_conntrack_htable_size;
nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
sizeof(struct nf_conn),
NFCT_INFOMASK + 1,
SLAB_TYPESAFE_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
if (!nf_conntrack_cachep)
goto err_cachep;
ret = nf_conntrack_expect_init();
if (ret < 0)
goto err_expect;
ret = nf_conntrack_helper_init();
if (ret < 0)
goto err_helper;
ret = nf_conntrack_proto_init();
if (ret < 0)
goto err_proto;
conntrack_gc_work_init(&conntrack_gc_work);
queue_delayed_work(system_power_efficient_wq, &conntrack_gc_work.dwork, HZ);
ret = register_nf_conntrack_bpf();
if (ret < 0)
goto err_kfunc;
return 0;
err_kfunc:
cancel_delayed_work_sync(&conntrack_gc_work.dwork);
nf_conntrack_proto_fini();
err_proto:
nf_conntrack_helper_fini();
err_helper:
nf_conntrack_expect_fini();
err_expect:
kmem_cache_destroy(nf_conntrack_cachep);
err_cachep:
kvfree(nf_conntrack_hash);
return ret;
}
static void nf_conntrack_set_closing(struct nf_conntrack *nfct)
{
struct nf_conn *ct = nf_ct_to_nf_conn(nfct);
switch (nf_ct_protonum(ct)) {
case IPPROTO_TCP:
nf_conntrack_tcp_set_closing(ct);
break;
}
}
static const struct nf_ct_hook nf_conntrack_hook = {
.update = nf_conntrack_update,
.destroy = nf_ct_destroy,
.get_tuple_skb = nf_conntrack_get_tuple_skb,
.attach = nf_conntrack_attach,
.set_closing = nf_conntrack_set_closing,
.confirm = __nf_conntrack_confirm,
};
void nf_conntrack_init_end(void)
{
RCU_INIT_POINTER(nf_ct_hook, &nf_conntrack_hook);
}
/*
* We need to use special "null" values, not used in hash table
*/
#define UNCONFIRMED_NULLS_VAL ((1<<30)+0)
int nf_conntrack_init_net(struct net *net)
{
struct nf_conntrack_net *cnet = nf_ct_pernet(net);
int ret = -ENOMEM;
BUILD_BUG_ON(IP_CT_UNTRACKED == IP_CT_NUMBER);
BUILD_BUG_ON_NOT_POWER_OF_2(CONNTRACK_LOCKS);
atomic_set(&cnet->count, 0);
net->ct.stat = alloc_percpu(struct ip_conntrack_stat);
if (!net->ct.stat)
return ret;
ret = nf_conntrack_expect_pernet_init(net);
if (ret < 0)
goto err_expect;
nf_conntrack_acct_pernet_init(net);
nf_conntrack_tstamp_pernet_init(net);
nf_conntrack_ecache_pernet_init(net);
nf_conntrack_proto_pernet_init(net);
return 0;
err_expect:
free_percpu(net->ct.stat);
return ret;
}
/* ctnetlink code shared by both ctnetlink and nf_conntrack_bpf */
int __nf_ct_change_timeout(struct nf_conn *ct, u64 timeout)
{
if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
return -EPERM;
__nf_ct_set_timeout(ct, timeout);
if (test_bit(IPS_DYING_BIT, &ct->status))
return -ETIME;
return 0;
}
EXPORT_SYMBOL_GPL(__nf_ct_change_timeout);
void __nf_ct_change_status(struct nf_conn *ct, unsigned long on, unsigned long off)
{
unsigned int bit;
/* Ignore these unchangable bits */
on &= ~IPS_UNCHANGEABLE_MASK;
off &= ~IPS_UNCHANGEABLE_MASK;
for (bit = 0; bit < __IPS_MAX_BIT; bit++) {
if (on & (1 << bit))
set_bit(bit, &ct->status);
else if (off & (1 << bit))
clear_bit(bit, &ct->status);
}
}
EXPORT_SYMBOL_GPL(__nf_ct_change_status);
int nf_ct_change_status_common(struct nf_conn *ct, unsigned int status)
{
unsigned long d;
d = ct->status ^ status;
if (d & (IPS_EXPECTED|IPS_CONFIRMED|IPS_DYING))
/* unchangeable */
return -EBUSY;
if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY))
/* SEEN_REPLY bit can only be set */
return -EBUSY;
if (d & IPS_ASSURED && !(status & IPS_ASSURED))
/* ASSURED bit can only be set */
return -EBUSY;
__nf_ct_change_status(ct, status, 0);
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_change_status_common);
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