netfilter: move nat hlist_head to nf_conn

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@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 2a5133e214c946e514067db236a33aa4d228e458..e5135d8728b4c565d86ec2db8ade5994b150ac65 100644 (file)
--- 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 b925395fa5ed712427fffc1f3f746fa9b1a61925..1c3035dda31f66a33d50cf2617d3a70288812383 100644 (file)
--- 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 344b1ab19220c34ec14b99b112ef3f5699a846f4..02515f7ed4cceceeaa9eb974531e2ec342346d07 100644 (file)
--- 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 1a9545965c0d285ebe6967863865ebbcc552cb60..02bcf00c24920b332401cd7c82ab6ced951659f5 100644 (file)
--- 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 6877a396f8fce12f47a6e4703e3725f7ac78bef9..692534701426cfae8c5f783d9e803180b0bf7c80 100644 (file)
--- 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,
 };