From: Florian Westphal <fw@xxxxxxxxx>
The nat extension structure is 32bytes in size on x86_64:
struct nf_conn_nat {
struct hlist_node bysource; /* 0 16 */
struct nf_conn * ct; /* 16 8 */
union nf_conntrack_nat_help help; /* 24 4 */
int masq_index; /* 28 4 */
/* size: 32, cachelines: 1, members: 4 */
/* last cacheline: 32 bytes */
};
The hlist is needed to quickly check for possible tuple collisions
when installing a new nat binding. Storing this in the extension
area has two drawbacks:
1. We need ct backpointer to get the conntrack struct from the extension.
2. When reallocation of extension area occurs we need to fixup the bysource
hash head via hlist_replace_rcu.
We can avoid both by placing the hlist_head in nf_conn and place nf_conn in
the bysource hash rather than the extenstion.
We can also remove the ->move support; no other extension needs it.
Moving the entire nat extension into nf_conn would be possible as well but
then we have to add yet another callback for deletion from the bysource
hash table rather than just using nat extension ->destroy hook for this.
nf_conn size doesn't increase due to aligment, followup patch replaces
hlist_node with single pointer.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/net/netfilter/nf_conntrack.h | 3 +++
include/net/netfilter/nf_conntrack_extend.h | 3 ---
include/net/netfilter/nf_nat.h | 2 --
net/netfilter/nf_conntrack_extend.c | 15 ++-----------
net/netfilter/nf_nat_core.c | 33 ++++++-----------------------
5 files changed, 12 insertions(+), 44 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 2a5133e..e5135d8 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -117,6 +117,9 @@ struct nf_conn {
/* Extensions */
struct nf_ct_ext *ext;
+#if IS_ENABLED(CONFIG_NF_NAT)
+ struct hlist_node nat_bysource;
+#endif
/* Storage reserved for other modules, must be the last member */
union nf_conntrack_proto proto;
};
diff --git a/include/net/netfilter/nf_conntrack_extend.h b/include/net/netfilter/nf_conntrack_extend.h
index b925395..1c3035d 100644
--- a/include/net/netfilter/nf_conntrack_extend.h
+++ b/include/net/netfilter/nf_conntrack_extend.h
@@ -99,9 +99,6 @@ void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id,
struct nf_ct_ext_type {
/* Destroys relationships (can be NULL). */
void (*destroy)(struct nf_conn *ct);
- /* Called when realloacted (can be NULL).
- Contents has already been moved. */
- void (*move)(void *new, void *old);
enum nf_ct_ext_id id;
diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 344b1ab..02515f7 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -29,8 +29,6 @@ struct nf_conn;
/* The structure embedded in the conntrack structure. */
struct nf_conn_nat {
- struct hlist_node bysource;
- struct nf_conn *ct;
union nf_conntrack_nat_help help;
#if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE_IPV4) || \
IS_ENABLED(CONFIG_NF_NAT_MASQUERADE_IPV6)
diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c
index 1a95459..02bcf00 100644
--- a/net/netfilter/nf_conntrack_extend.c
+++ b/net/netfilter/nf_conntrack_extend.c
@@ -73,7 +73,7 @@ void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id,
size_t var_alloc_len, gfp_t gfp)
{
struct nf_ct_ext *old, *new;
- int i, newlen, newoff;
+ int newlen, newoff;
struct nf_ct_ext_type *t;
/* Conntrack must not be confirmed to avoid races on reallocation. */
@@ -99,19 +99,8 @@ void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id,
return NULL;
if (new != old) {
- for (i = 0; i < NF_CT_EXT_NUM; i++) {
- if (!__nf_ct_ext_exist(old, i))
- continue;
-
- rcu_read_lock();
- t = rcu_dereference(nf_ct_ext_types[i]);
- if (t && t->move)
- t->move((void *)new + new->offset[i],
- (void *)old + old->offset[i]);
- rcu_read_unlock();
- }
kfree_rcu(old, rcu);
- ct->ext = new;
+ rcu_assign_pointer(ct->ext, new);
}
new->offset[id] = newoff;
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 6877a39..6925347 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -198,11 +198,9 @@ find_appropriate_src(struct net *net,
const struct nf_nat_range *range)
{
unsigned int h = hash_by_src(net, tuple);
- const struct nf_conn_nat *nat;
const struct nf_conn *ct;
- hlist_for_each_entry_rcu(nat, &nf_nat_bysource[h], bysource) {
- ct = nat->ct;
+ hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
if (same_src(ct, tuple) &&
net_eq(net, nf_ct_net(ct)) &&
nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
@@ -435,8 +433,7 @@ nf_nat_setup_info(struct nf_conn *ct,
spin_lock_bh(&nf_nat_lock);
/* nf_conntrack_alter_reply might re-allocate extension aera */
nat = nfct_nat(ct);
- nat->ct = ct;
- hlist_add_head_rcu(&nat->bysource,
+ hlist_add_head_rcu(&ct->nat_bysource,
&nf_nat_bysource[srchash]);
spin_unlock_bh(&nf_nat_lock);
}
@@ -543,7 +540,7 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
if (nf_nat_proto_remove(ct, data))
return 1;
- if (!nat || !nat->ct)
+ if (!nat)
return 0;
/* This netns is being destroyed, and conntrack has nat null binding.
@@ -556,9 +553,8 @@ static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
return 1;
spin_lock_bh(&nf_nat_lock);
- hlist_del_rcu(&nat->bysource);
+ hlist_del_rcu(&ct->nat_bysource);
ct->status &= ~IPS_NAT_DONE_MASK;
- nat->ct = NULL;
spin_unlock_bh(&nf_nat_lock);
add_timer(&ct->timeout);
@@ -688,27 +684,13 @@ static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
{
struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
- if (nat == NULL || nat->ct == NULL)
+ if (!nat)
return;
- NF_CT_ASSERT(nat->ct->status & IPS_SRC_NAT_DONE);
-
- spin_lock_bh(&nf_nat_lock);
- hlist_del_rcu(&nat->bysource);
- spin_unlock_bh(&nf_nat_lock);
-}
-
-static void nf_nat_move_storage(void *new, void *old)
-{
- struct nf_conn_nat *new_nat = new;
- struct nf_conn_nat *old_nat = old;
- struct nf_conn *ct = old_nat->ct;
-
- if (!ct || !(ct->status & IPS_SRC_NAT_DONE))
- return;
+ NF_CT_ASSERT(ct->status & IPS_SRC_NAT_DONE);
spin_lock_bh(&nf_nat_lock);
- hlist_replace_rcu(&old_nat->bysource, &new_nat->bysource);
+ hlist_del_rcu(&ct->nat_bysource);
spin_unlock_bh(&nf_nat_lock);
}
@@ -716,7 +698,6 @@ static struct nf_ct_ext_type nat_extend __read_mostly = {
.len = sizeof(struct nf_conn_nat),
.align = __alignof__(struct nf_conn_nat),
.destroy = nf_nat_cleanup_conntrack,
- .move = nf_nat_move_storage,
.id = NF_CT_EXT_NAT,
.flags = NF_CT_EXT_F_PREALLOC,
};
--
2.1.4
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