[NETFILTER]: nf_conntrack_expect: introduce nf_conntrack_expect_max sysct
As a last step of preventing DoS by creating lots of expectations, this
patch introduces a global maximum and a sysctl to control it. The default
is initialized to 4 * the expectation hash table size, which results in
1/64 of the default maxmimum of conntracks.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index 5ef0dd4..513828f 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c
@@ -35,6 +35,7 @@
static unsigned int nf_ct_expect_hash_rnd __read_mostly;
static unsigned int nf_ct_expect_count;
+unsigned int nf_ct_expect_max __read_mostly;
static int nf_ct_expect_hash_rnd_initted __read_mostly;
static int nf_ct_expect_vmalloc;
@@ -367,6 +368,14 @@
master_help->expecting >= master_help->helper->max_expected)
evict_oldest_expect(master);
+ if (nf_ct_expect_count >= nf_ct_expect_max) {
+ if (net_ratelimit())
+ printk(KERN_WARNING
+ "nf_conntrack: expectation table full");
+ ret = -EMFILE;
+ goto out;
+ }
+
nf_ct_expect_insert(expect);
nf_ct_expect_event(IPEXP_NEW, expect);
ret = 0;
@@ -522,6 +531,7 @@
if (!nf_ct_expect_hsize)
nf_ct_expect_hsize = 1;
}
+ nf_ct_expect_max = nf_ct_expect_hsize * 4;
nf_ct_expect_hash = nf_ct_alloc_hashtable(&nf_ct_expect_hsize,
&nf_ct_expect_vmalloc);