From: Florian Westphal <fw@xxxxxxxxx>
Its not needed anymore:
A. If entry is totally new, then the rcu-protected resource
must already have been removed from global visibility before call
to nf_ct_iterate_destroy.
B. If entry was allocated before, but is not yet in the hash table
(uncofirmed case), genid gets incremented and synchronize_rcu() call
makes sure access has completed.
C. Next attempt to peek at extension area will fail for unconfirmed
conntracks, because ext->genid != genid.
D. Conntracks in the hash are iterated as before.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/netfilter/nf_conntrack_core.c | 46 ++++++++---------------------
net/netfilter/nf_conntrack_helper.c | 5 ----
net/netfilter/nfnetlink_cttimeout.c | 1 -
3 files changed, 13 insertions(+), 39 deletions(-)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 76310940cbd7..7b4b3f5db959 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2457,34 +2457,6 @@ static int iter_net_only(struct nf_conn *i, void *data)
return d->iter(i, d->data);
}
-static void
-__nf_ct_unconfirmed_destroy(struct net *net)
-{
- int cpu;
-
- for_each_possible_cpu(cpu) {
- struct nf_conntrack_tuple_hash *h;
- struct hlist_nulls_node *n;
- struct ct_pcpu *pcpu;
-
- pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
-
- spin_lock_bh(&pcpu->lock);
- hlist_nulls_for_each_entry(h, n, &pcpu->unconfirmed, hnnode) {
- struct nf_conn *ct;
-
- ct = nf_ct_tuplehash_to_ctrack(h);
-
- /* we cannot call iter() on unconfirmed list, the
- * owning cpu can reallocate ct->ext at any time.
- */
- set_bit(IPS_DYING_BIT, &ct->status);
- }
- spin_unlock_bh(&pcpu->lock);
- cond_resched();
- }
-}
-
void nf_ct_iterate_cleanup_net(struct net *net,
int (*iter)(struct nf_conn *i, void *data),
void *data, u32 portid, int report)
@@ -2527,26 +2499,34 @@ nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
if (atomic_read(&cnet->count) == 0)
continue;
- __nf_ct_unconfirmed_destroy(net);
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 our __nf_ct_unconfirmed_destroy() might
- * not have affected all namespaces.
+ * the global list, so hook drop above might not have
+ * affected all namespaces.
*/
net_ns_barrier();
- /* a conntrack could have been unlinked from unconfirmed list
- * before we grabbed pcpu lock in __nf_ct_unconfirmed_destroy().
+ /* 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();
nf_ct_iterate_cleanup(iter, data, 0, 0);
+
+ /* 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);
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 8dec42ec603e..c12a87ebc3ee 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -468,11 +468,6 @@ void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
nf_ct_iterate_destroy(unhelp, me);
-
- /* Maybe someone has gotten the helper already when unhelp above.
- * So need to wait it.
- */
- synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index 9bc4ebe65faa..f069c24c6146 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -674,7 +674,6 @@ static void __exit cttimeout_exit(void)
RCU_INIT_POINTER(nf_ct_timeout_hook, NULL);
nf_ct_iterate_destroy(untimeout, NULL);
- synchronize_rcu();
}
module_init(cttimeout_init);
--
2.30.2
