Undocumented historical behavior inherited from ip_conntrack (ipv4 only ancestor) days. If set to 0, no limit is applied. conntrack table can grow to huge value, only limited by size of conntrack table and the kernel-internal upper limit on the hash chain lengths. This feature makes no sense; users can just set conntrack_max=2147483647 (INT_MAX) if tehy want. Disallow a 0 value. This will make it slightly easier to allow per-netns constraints for this value in a future patch. Signed-off-by: Florian Westphal --- net/netfilter/nf_conntrack_core.c | 2 +- net/netfilter/nf_conntrack_standalone.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 344f88295976..0b95f226f211 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1668,7 +1668,7 @@ __nf_conntrack_alloc(struct net *net, /* We don't want any race condition at early drop stage */ ct_count = atomic_inc_return(&cnet->count); - if (nf_conntrack_max && unlikely(ct_count > nf_conntrack_max)) { + if (unlikely(ct_count > nf_conntrack_max)) { if (!early_drop(net, hash)) { if (!conntrack_gc_work.early_drop) conntrack_gc_work.early_drop = true; diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 708b79380f04..207b240b14e5 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -648,7 +648,7 @@ static struct ctl_table nf_ct_sysctl_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ZERO, + .extra1 = SYSCTL_ONE, .extra2 = SYSCTL_INT_MAX, }, [NF_SYSCTL_CT_COUNT] = { @@ -929,7 +929,7 @@ static struct ctl_table nf_ct_netfilter_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ZERO, + .extra1 = SYSCTL_ONE, .extra2 = SYSCTL_INT_MAX, }, }; -- 2.51.0