[PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit

Eric Dumazet
2010-06-04T16:25:37Z

Le vendredi 04 juin 2010 à 14:36 +0200, Eric Dumazet a écrit :
> Le vendredi 04 juin 2010 à 14:29 +0200, Patrick McHardy a écrit :
> > Changli Gao wrote:
> > > On Fri, Jun 4, 2010 at 7:40 PM, Patrick McHardy <kaber@trash.net> wrote:
> > >> Eric Dumazet wrote:
> > >>> Obviously, an IPS_UNTRACKED bit would be much easier to implement.
> > >>> Would it be acceptable ?
> > >> That also would be fine. However the main idea behind using a nfctinfo
> > >> bit was that we wouldn't need the untracked conntrack anymore at all.
> > >> But I guess a per-cpu untrack conntrack would already be an improvement
> > >> over the current situation.
> > >
> > > I think Eric didn't mean ip_conntrack_info but ip_conntrack_status
> > > bit. Since we have had a IPS_TEMPLATE bit, I think another
> > > IPS_UNTRACKED bit is also acceptable.
> >
> > Yes, of course. But using one of these bits implies that we'd still
> > have the untracked conntrack.
>
> Yes, it was my idea, with a per_cpu untracked conntrack.
>
> I'll submit a patch, thanks.
>
>

Here is first part, introducing IPS_UNTRACKED bit and various helpers to
abstract nf_conntrack_untracked access.

I'll cook second patch in a couple of hours for per_cpu conversion.

Thanks !

[PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit

NOTRACK makes all cpus share a cache line on nf_conntrack_untracked
twice per packet. This is bad for performance.
__read_mostly annotation is also a bad choice.

This patch introduces IPS_UNTRACKED bit so that we can use later a
per_cpu untrack structure more easily.

A new helper, nf_ct_untracked_get() returns a pointer to
nf_conntrack_untracked.

Another one, nf_ct_untracked_status_or() is used by nf_nat_init() to add
IPS_NAT_DONE_MASK bits to untracked status.

nf_ct_is_untracked() prototype is changed to work on a nf_conn pointer.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
include/linux/netfilter/nf_conntrack_common.h | 4 ++++
include/net/netfilter/nf_conntrack.h | 12 +++++++++---
include/net/netfilter/nf_conntrack_core.h | 2 +-
net/ipv4/netfilter/nf_nat_core.c | 2 +-
net/ipv4/netfilter/nf_nat_standalone.c | 2 +-
net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c | 2 +-
net/netfilter/nf_conntrack_core.c | 11 ++++++++---
net/netfilter/nf_conntrack_netlink.c | 2 +-
net/netfilter/xt_CT.c | 4 ++--
net/netfilter/xt_NOTRACK.c | 2 +-
net/netfilter/xt_TEE.c | 4 ++--
net/netfilter/xt_cluster.c | 2 +-
net/netfilter/xt_conntrack.c | 11 ++++++-----
net/netfilter/xt_socket.c | 2 +-
net/netfilter/xt_state.c | 14 ++++++++------
15 files changed, 47 insertions(+), 29 deletions(-)

diff --git a/include/linux/netfilter/nf_conntrack_common.h b/include/linux/netfilter/nf_conntrack_common.h
index 14e6d32..1afd18c 100644
--- a/include/linux/netfilter/nf_conntrack_common.h
+++ b/include/linux/netfilter/nf_conntrack_common.h
@@ -76,6 +76,10 @@ enum ip_conntrack_status {
/* Conntrack is a template */
IPS_TEMPLATE_BIT = 11,
IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT),
+
+ /* Conntrack is a fake untracked entry */
+ IPS_UNTRACKED_BIT = 12,
+ IPS_UNTRACKED = (1 << IPS_UNTRACKED_BIT),
};

/* Connection tracking event types */
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index bde095f..3bc38c7 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -261,7 +261,13 @@ extern s16 (*nf_ct_nat_offset)(const struct nf_conn *ct,
u32 seq);

/* Fake conntrack entry for untracked connections */
-extern struct nf_conn nf_conntrack_untracked;
+static inline struct nf_conn *nf_ct_untracked_get(void)
+{
+ extern struct nf_conn nf_conntrack_untracked;
+
+ return &nf_conntrack_untracked;
+}
+extern void nf_ct_untracked_status_or(unsigned long bits);

/* Iterate over all conntracks: if iter returns true, it's deleted. */
extern void
@@ -289,9 +295,9 @@ static inline int nf_ct_is_dying(struct nf_conn *ct)
return test_bit(IPS_DYING_BIT, &ct->status);
}

-static inline int nf_ct_is_untracked(const struct sk_buff *skb)
+static inline int nf_ct_is_untracked(const struct nf_conn *ct)
{
- return (skb->nfct == &nf_conntrack_untracked.ct_general);
+ return test_bit(IPS_UNTRACKED_BIT, &ct->status);
}

extern int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp);
diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index 3d7524f..aced085 100644
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -60,7 +60,7 @@ static inline int nf_conntrack_confirm(struct sk_buff *skb)
struct nf_conn *ct = (struct nf_conn *)skb->nfct;
int ret = NF_ACCEPT;

- if (ct && ct != &nf_conntrack_untracked) {
+ if (ct && !nf_ct_is_untracked(ct)) {
if (!nf_ct_is_confirmed(ct))
ret = __nf_conntrack_confirm(skb);
if (likely(ret == NF_ACCEPT))
diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 4f8bddb..c7719b2 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -742,7 +742,7 @@ static int __init nf_nat_init(void)
spin_unlock_bh(&nf_nat_lock);

/* Initialize fake conntrack so that NAT will skip it */
- nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
+ nf_ct_untracked_status_or(IPS_NAT_DONE_MASK);

l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);

diff --git a/net/ipv4/netfilter/nf_nat_standalone.c b/net/ipv4/netfilter/nf_nat_standalone.c
index beb2581..6723c68 100644
--- a/net/ipv4/netfilter/nf_nat_standalone.c
+++ b/net/ipv4/netfilter/nf_nat_standalone.c
@@ -98,7 +98,7 @@ nf_nat_fn(unsigned int hooknum,
return NF_ACCEPT;

/* Don't try to NAT if this packet is not conntracked */
- if (ct == &nf_conntrack_untracked)
+ if (nf_ct_is_untracked(ct))
return NF_ACCEPT;

nat = nfct_nat(ct);
diff --git a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
index 9be8177..1df3c8b 100644
--- a/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c
@@ -208,7 +208,7 @@ icmpv6_error(struct net *net, struct nf_conn *tmpl,
type = icmp6h->icmp6_type - 130;
if (type >= 0 && type < sizeof(noct_valid_new) &&
noct_valid_new[type]) {
- skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfct = &nf_ct_untracked_get()->ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);
return NF_ACCEPT;
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index eeeb8bc..6c1da21 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -62,7 +62,7 @@ EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
unsigned int nf_conntrack_max __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_max);

-struct nf_conn nf_conntrack_untracked __read_mostly;
+struct nf_conn nf_conntrack_untracked;
EXPORT_SYMBOL_GPL(nf_conntrack_untracked);

static int nf_conntrack_hash_rnd_initted;
@@ -1321,6 +1321,12 @@ EXPORT_SYMBOL_GPL(nf_conntrack_set_hashsize);
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)
+{
+ nf_conntrack_untracked.status |= bits;
+}
+EXPORT_SYMBOL_GPL(nf_ct_untracked_status_or);
+
static int nf_conntrack_init_init_net(void)
{
int max_factor = 8;
@@ -1368,8 +1374,7 @@ static int nf_conntrack_init_init_net(void)
#endif
atomic_set(&nf_conntrack_untracked.ct_general.use, 1);
/* - and look it like as a confirmed connection */
- set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status);
-
+ nf_ct_untracked_status_or(IPS_CONFIRMED | IPS_UNTRACKED);
return 0;

#ifdef CONFIG_NF_CONNTRACK_ZONES
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index c42ff6a..5bae1cd 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -480,7 +480,7 @@ ctnetlink_conntrack_event(unsigned int events, struct nf_ct_event *item)
int err;

/* ignore our fake conntrack entry */
- if (ct == &nf_conntrack_untracked)
+ if (nf_ct_is_untracked(ct))
return 0;

if (events & (1 << IPCT_DESTROY)) {
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index 562bf32..0cb6053 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -67,7 +67,7 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par)
return -EINVAL;

if (info->flags & XT_CT_NOTRACK) {
- ct = &nf_conntrack_untracked;
+ ct = nf_ct_untracked_get();
atomic_inc(&ct->ct_general.use);
goto out;
}
@@ -132,7 +132,7 @@ static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par)
struct nf_conn *ct = info->ct;
struct nf_conn_help *help;

- if (ct != &nf_conntrack_untracked) {
+ if (!nf_ct_is_untracked(ct)) {
help = nfct_help(ct);
if (help)
module_put(help->helper->me);
diff --git a/net/netfilter/xt_NOTRACK.c b/net/netfilter/xt_NOTRACK.c
index 512b912..9d78218 100644
--- a/net/netfilter/xt_NOTRACK.c
+++ b/net/netfilter/xt_NOTRACK.c
@@ -23,7 +23,7 @@ notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
If there is a real ct entry correspondig to this packet,
it'll hang aroun till timing out. We don't deal with it
for performance reasons. JK */
- skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfct = &nf_ct_untracked_get()->ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);

diff --git a/net/netfilter/xt_TEE.c b/net/netfilter/xt_TEE.c
index 859d9fd..7a11826 100644
--- a/net/netfilter/xt_TEE.c
+++ b/net/netfilter/xt_TEE.c
@@ -104,7 +104,7 @@ tee_tg4(struct sk_buff *skb, const struct xt_action_param *par)
#ifdef WITH_CONNTRACK
/* Avoid counting cloned packets towards the original connection. */
nf_conntrack_put(skb->nfct);
- skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfct = &nf_ct_untracked_get()->ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);
#endif
@@ -177,7 +177,7 @@ tee_tg6(struct sk_buff *skb, const struct xt_action_param *par)

#ifdef WITH_CONNTRACK
nf_conntrack_put(skb->nfct);
- skb->nfct = &nf_conntrack_untracked.ct_general;
+ skb->nfct = &nf_ct_untracked_get()->ct_general;
skb->nfctinfo = IP_CT_NEW;
nf_conntrack_get(skb->nfct);
#endif
diff --git a/net/netfilter/xt_cluster.c b/net/netfilter/xt_cluster.c
index 30b95a1..f4af1bf 100644
--- a/net/netfilter/xt_cluster.c
+++ b/net/netfilter/xt_cluster.c
@@ -120,7 +120,7 @@ xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par)
if (ct == NULL)
return false;

- if (ct == &nf_conntrack_untracked)
+ if (nf_ct_is_untracked(ct))
return false;

if (ct->master)
diff --git a/net/netfilter/xt_conntrack.c b/net/netfilter/xt_conntrack.c
index 39681f1..e536710 100644
--- a/net/netfilter/xt_conntrack.c
+++ b/net/netfilter/xt_conntrack.c
@@ -123,11 +123,12 @@ conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,

ct = nf_ct_get(skb, &ctinfo);

- if (ct == &nf_conntrack_untracked)
- statebit = XT_CONNTRACK_STATE_UNTRACKED;
- else if (ct != NULL)
- statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
- else
+ if (ct) {
+ if (nf_ct_is_untracked(ct))
+ statebit = XT_CONNTRACK_STATE_UNTRACKED;
+ else
+ statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
+ } else
statebit = XT_CONNTRACK_STATE_INVALID;

if (info->match_flags & XT_CONNTRACK_STATE) {
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index 3d54c23..1ca8990 100644
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -127,7 +127,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
* reply packet of an established SNAT-ted connection. */

ct = nf_ct_get(skb, &ctinfo);
- if (ct && (ct != &nf_conntrack_untracked) &&
+ if (ct && !nf_ct_is_untracked(ct) &&
((iph->protocol != IPPROTO_ICMP &&
ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) ||
(iph->protocol == IPPROTO_ICMP &&
diff --git a/net/netfilter/xt_state.c b/net/netfilter/xt_state.c
index e12e053..a507922 100644
--- a/net/netfilter/xt_state.c
+++ b/net/netfilter/xt_state.c
@@ -26,14 +26,16 @@ state_mt(const struct sk_buff *skb, struct xt_action_param *par)
const struct xt_state_info *sinfo = par->matchinfo;
enum ip_conntrack_info ctinfo;
unsigned int statebit;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

- if (nf_ct_is_untracked(skb))
- statebit = XT_STATE_UNTRACKED;
- else if (!nf_ct_get(skb, &ctinfo))
+ if (!ct)
statebit = XT_STATE_INVALID;
- else
- statebit = XT_STATE_BIT(ctinfo);
-
+ else {
+ if (nf_ct_is_untracked(ct))
+ statebit = XT_STATE_UNTRACKED;
+ else
+ statebit = XT_STATE_BIT(ctinfo);
+ }
return (sinfo->statemask & statebit);
}