[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/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h
index 9d5af4e..cae1a0d 100644
--- a/include/net/netfilter/nf_conntrack_expect.h
+++ b/include/net/netfilter/nf_conntrack_expect.h
@@ -8,6 +8,7 @@
extern struct hlist_head *nf_ct_expect_hash;
extern unsigned int nf_ct_expect_hsize;
+extern unsigned int nf_ct_expect_max;
struct nf_conntrack_expect
{
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);
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 098e799..6af96c6 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -372,7 +372,14 @@
.extra1 = &log_invalid_proto_min,
.extra2 = &log_invalid_proto_max,
},
-
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "nf_conntrack_expect_max",
+ .data = &nf_ct_expect_max,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
{ .ctl_name = 0 }
};
