netfilter: kill the fake untracked conntrack objects
resurrect an old patch from Pablo Neira to remove the untracked objects.
Currently, there are four possible states of an skb wrt. conntrack.
1. No conntrack attached, ct is NULL.
2. Normal (kmem cache allocated) ct attached.
3. a template (kmalloc'd), not in any hash tables at any point in time
4. the 'untracked' conntrack, a percpu nf_conn object, tagged via
IPS_UNTRACKED_BIT in ct->status.
Untracked is supposed to be identical to case 1. It exists only
so users can check
-m conntrack --ctstate UNTRACKED vs.
-m conntrack --ctstate INVALID
e.g. attempts to set connmark on INVALID or UNTRACKED conntracks is
supposed to be a no-op.
Thus currently we need to check
ct == NULL || nf_ct_is_untracked(ct)
in a lot of places in order to avoid altering untracked objects.
The other consequence of the percpu untracked object is that all
-j NOTRACK (and, later, kfree_skb of such skbs) result in an atomic op
(inc/dec the untracked conntracks refcount).
This adds a new kernel-private ctinfo state, IP_CT_UNTRACKED, to
make the distinction instead.
The (few) places that care about packet invalid (ct is NULL) vs.
packet untracked now need to test ct == NULL vs. ctinfo == IP_CT_UNTRACKED,
but all other places can omit the nf_ct_is_untracked() check.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 8a4a57b8..9a75d99 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -1556,12 +1556,8 @@
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
if (!ct || !nf_ct_is_untracked(ct)) {
- struct nf_conn *untracked;
-
nf_conntrack_put(&ct->ct_general);
- untracked = nf_ct_untracked_get();
- nf_conntrack_get(&untracked->ct_general);
- nf_ct_set(skb, untracked, IP_CT_NEW);
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
}
#endif
}
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 1960587..012b99f 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -243,14 +243,6 @@
enum ip_conntrack_dir dir,
u32 seq);
-/* Fake conntrack entry for untracked connections */
-DECLARE_PER_CPU_ALIGNED(struct nf_conn, nf_conntrack_untracked);
-static inline struct nf_conn *nf_ct_untracked_get(void)
-{
- return raw_cpu_ptr(&nf_conntrack_untracked);
-}
-void nf_ct_untracked_status_or(unsigned long bits);
-
/* Iterate over all conntracks: if iter returns true, it's deleted. */
void nf_ct_iterate_cleanup(struct net *net,
int (*iter)(struct nf_conn *i, void *data),
@@ -283,7 +275,7 @@
static inline int nf_ct_is_untracked(const struct nf_conn *ct)
{
- return test_bit(IPS_UNTRACKED_BIT, &ct->status);
+ return false;
}
/* Packet is received from loopback */
diff --git a/include/uapi/linux/netfilter/nf_conntrack_common.h b/include/uapi/linux/netfilter/nf_conntrack_common.h
index 6a8e33d..b4a0a19 100644
--- a/include/uapi/linux/netfilter/nf_conntrack_common.h
+++ b/include/uapi/linux/netfilter/nf_conntrack_common.h
@@ -28,12 +28,14 @@
/* only for userspace compatibility */
#ifndef __KERNEL__
IP_CT_NEW_REPLY = IP_CT_NUMBER,
+#else
+ IP_CT_UNTRACKED = 7,
#endif
};
#define NF_CT_STATE_INVALID_BIT (1 << 0)
#define NF_CT_STATE_BIT(ctinfo) (1 << ((ctinfo) % IP_CT_IS_REPLY + 1))
-#define NF_CT_STATE_UNTRACKED_BIT (1 << (IP_CT_NUMBER + 1))
+#define NF_CT_STATE_UNTRACKED_BIT (1 << (IP_CT_UNTRACKED + 1))
/* Bitset representing status of connection. */
enum ip_conntrack_status {
@@ -94,7 +96,7 @@
IPS_TEMPLATE_BIT = 11,
IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT),
- /* Conntrack is a fake untracked entry */
+ /* Conntrack is a fake untracked entry. Obsolete and not used anymore */
IPS_UNTRACKED_BIT = 12,
IPS_UNTRACKED = (1 << IPS_UNTRACKED_BIT),
diff --git a/net/ipv4/netfilter/nf_dup_ipv4.c b/net/ipv4/netfilter/nf_dup_ipv4.c
index f0dbff0..39895b9 100644
--- a/net/ipv4/netfilter/nf_dup_ipv4.c
+++ b/net/ipv4/netfilter/nf_dup_ipv4.c
@@ -69,8 +69,7 @@
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
/* Avoid counting cloned packets towards the original connection. */
nf_reset(skb);
- nf_ct_set(skb, nf_ct_untracked_get(), IP_CT_NEW);
- nf_conntrack_get(skb_nfct(skb));
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
#endif
/*
* If we are in PREROUTING/INPUT, decrease the TTL to mitigate potential
diff --git a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
index d2c2ccb..d5f028e 100644
--- a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
@@ -221,8 +221,7 @@
type = icmp6h->icmp6_type - 130;
if (type >= 0 && type < sizeof(noct_valid_new) &&
noct_valid_new[type]) {
- nf_ct_set(skb, nf_ct_untracked_get(), IP_CT_NEW);
- nf_conntrack_get(skb_nfct(skb));
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
return NF_ACCEPT;
}
diff --git a/net/ipv6/netfilter/nf_dup_ipv6.c b/net/ipv6/netfilter/nf_dup_ipv6.c
index 888ecd1..4a7dded 100644
--- a/net/ipv6/netfilter/nf_dup_ipv6.c
+++ b/net/ipv6/netfilter/nf_dup_ipv6.c
@@ -58,8 +58,7 @@
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
nf_reset(skb);
- nf_ct_set(skb, nf_ct_untracked_get(), IP_CT_NEW);
- nf_conntrack_get(skb_nfct(skb));
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
#endif
if (hooknum == NF_INET_PRE_ROUTING ||
hooknum == NF_INET_LOCAL_IN) {
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index bcf1d2a..03150f6 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -180,14 +180,6 @@
unsigned int nf_conntrack_max __read_mostly;
seqcount_t nf_conntrack_generation __read_mostly;
-
-/* nf_conn must be 8 bytes aligned, as the 3 LSB bits are used
- * for the nfctinfo. We cheat by (ab)using the PER CPU cache line
- * alignment to enforce this.
- */
-DEFINE_PER_CPU_ALIGNED(struct nf_conn, nf_conntrack_untracked);
-EXPORT_PER_CPU_SYMBOL(nf_conntrack_untracked);
-
static unsigned int nf_conntrack_hash_rnd __read_mostly;
static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple,
@@ -1314,9 +1306,10 @@
int ret;
tmpl = nf_ct_get(skb, &ctinfo);
- if (tmpl) {
+ if (tmpl || ctinfo == IP_CT_UNTRACKED) {
/* Previously seen (loopback or untracked)? Ignore. */
- if (!nf_ct_is_template(tmpl)) {
+ if ((tmpl && !nf_ct_is_template(tmpl)) ||
+ ctinfo == IP_CT_UNTRACKED) {
NF_CT_STAT_INC_ATOMIC(net, ignore);
return NF_ACCEPT;
}
@@ -1629,18 +1622,6 @@
}
EXPORT_SYMBOL_GPL(nf_ct_free_hashtable);
-static int untrack_refs(void)
-{
- int cnt = 0, cpu;
-
- for_each_possible_cpu(cpu) {
- struct nf_conn *ct = &per_cpu(nf_conntrack_untracked, cpu);
-
- cnt += atomic_read(&ct->ct_general.use) - 1;
- }
- return cnt;
-}
-
void nf_conntrack_cleanup_start(void)
{
conntrack_gc_work.exiting = true;
@@ -1650,8 +1631,6 @@
void nf_conntrack_cleanup_end(void)
{
RCU_INIT_POINTER(nf_ct_destroy, NULL);
- while (untrack_refs() > 0)
- schedule();
cancel_delayed_work_sync(&conntrack_gc_work.dwork);
nf_ct_free_hashtable(nf_conntrack_hash, nf_conntrack_htable_size);
@@ -1825,20 +1804,11 @@
module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
&nf_conntrack_htable_size, 0600);
-void nf_ct_untracked_status_or(unsigned long bits)
-{
- int cpu;
-
- for_each_possible_cpu(cpu)
- per_cpu(nf_conntrack_untracked, cpu).status |= bits;
-}
-EXPORT_SYMBOL_GPL(nf_ct_untracked_status_or);
-
int nf_conntrack_init_start(void)
{
int max_factor = 8;
int ret = -ENOMEM;
- int i, cpu;
+ int i;
seqcount_init(&nf_conntrack_generation);
@@ -1921,15 +1891,6 @@
if (ret < 0)
goto err_proto;
- /* Set up fake conntrack: to never be deleted, not in any hashes */
- for_each_possible_cpu(cpu) {
- struct nf_conn *ct = &per_cpu(nf_conntrack_untracked, cpu);
- write_pnet(&ct->ct_net, &init_net);
- atomic_set(&ct->ct_general.use, 1);
- }
- /* - and look it like as a confirmed connection */
- nf_ct_untracked_status_or(IPS_CONFIRMED | IPS_UNTRACKED);
-
conntrack_gc_work_init(&conntrack_gc_work);
queue_delayed_work(system_long_wq, &conntrack_gc_work.dwork, HZ);
@@ -1977,6 +1938,7 @@
int ret = -ENOMEM;
int cpu;
+ BUILD_BUG_ON(IP_CT_UNTRACKED == IP_CT_NUMBER);
atomic_set(&net->ct.count, 0);
net->ct.pcpu_lists = alloc_percpu(struct ct_pcpu);
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 5e35643..9cbf49f 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -861,9 +861,6 @@
nf_ct_helper_expectfn_register(&follow_master_nat);
- /* Initialize fake conntrack so that NAT will skip it */
- nf_ct_untracked_status_or(IPS_NAT_DONE_MASK);
-
BUG_ON(nfnetlink_parse_nat_setup_hook != NULL);
RCU_INIT_POINTER(nfnetlink_parse_nat_setup_hook,
nfnetlink_parse_nat_setup);
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 6e23dbb..6c6fd48 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -72,12 +72,12 @@
switch (priv->key) {
case NFT_CT_STATE:
- if (ct == NULL)
- state = NF_CT_STATE_INVALID_BIT;
- else if (nf_ct_is_untracked(ct))
+ if (ct)
+ state = NF_CT_STATE_BIT(ctinfo);
+ else if (ctinfo == IP_CT_UNTRACKED)
state = NF_CT_STATE_UNTRACKED_BIT;
else
- state = NF_CT_STATE_BIT(ctinfo);
+ state = NF_CT_STATE_INVALID_BIT;
*dest = state;
return;
default:
@@ -718,12 +718,10 @@
ct = nf_ct_get(pkt->skb, &ctinfo);
/* Previously seen (loopback or untracked)? Ignore. */
- if (ct)
+ if (ct || ctinfo == IP_CT_UNTRACKED)
return;
- ct = nf_ct_untracked_get();
- atomic_inc(&ct->ct_general.use);
- nf_ct_set(skb, ct, IP_CT_NEW);
+ nf_ct_set(skb, ct, IP_CT_UNTRACKED);
}
static struct nft_expr_type nft_notrack_type;
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index b008db0..3cbe1bc 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -26,11 +26,12 @@
if (skb->_nfct != 0)
return XT_CONTINUE;
- /* special case the untracked ct : we want the percpu object */
- if (!ct)
- ct = nf_ct_untracked_get();
- atomic_inc(&ct->ct_general.use);
- nf_ct_set(skb, ct, IP_CT_NEW);
+ if (ct) {
+ atomic_inc(&ct->ct_general.use);
+ nf_ct_set(skb, ct, IP_CT_NEW);
+ } else {
+ nf_ct_set(skb, ct, IP_CT_UNTRACKED);
+ }
return XT_CONTINUE;
}
@@ -335,7 +336,7 @@
struct nf_conn *ct = info->ct;
struct nf_conn_help *help;
- if (ct && !nf_ct_is_untracked(ct)) {
+ if (ct) {
help = nfct_help(ct);
if (help)
module_put(help->helper->me);
@@ -412,8 +413,7 @@
if (skb->_nfct != 0)
return XT_CONTINUE;
- nf_ct_set(skb, nf_ct_untracked_get(), IP_CT_NEW);
- nf_conntrack_get(skb_nfct(skb));
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
return XT_CONTINUE;
}
diff --git a/net/netfilter/xt_conntrack.c b/net/netfilter/xt_conntrack.c
index c0fb217..39cf1d0 100644
--- a/net/netfilter/xt_conntrack.c
+++ b/net/netfilter/xt_conntrack.c
@@ -172,12 +172,11 @@
ct = nf_ct_get(skb, &ctinfo);
- if (ct) {
- if (nf_ct_is_untracked(ct))
- statebit = XT_CONNTRACK_STATE_UNTRACKED;
- else
- statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
- } else
+ if (ct)
+ statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
+ else if (ctinfo == IP_CT_UNTRACKED)
+ statebit = XT_CONNTRACK_STATE_UNTRACKED;
+ else
statebit = XT_CONNTRACK_STATE_INVALID;
if (info->match_flags & XT_CONNTRACK_STATE) {
diff --git a/net/netfilter/xt_state.c b/net/netfilter/xt_state.c
index 5746a33..5fbd791 100644
--- a/net/netfilter/xt_state.c
+++ b/net/netfilter/xt_state.c
@@ -28,14 +28,13 @@
unsigned int statebit;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
- if (!ct)
+ if (ct)
+ statebit = XT_STATE_BIT(ctinfo);
+ else if (ctinfo == IP_CT_UNTRACKED)
+ statebit = XT_STATE_UNTRACKED;
+ else
statebit = XT_STATE_INVALID;
- else {
- if (nf_ct_is_untracked(ct))
- statebit = XT_STATE_UNTRACKED;
- else
- statebit = XT_STATE_BIT(ctinfo);
- }
+
return (sinfo->statemask & statebit);
}