[PATCH net 14/14] netfilter: nf_conntrack_helper: cap maximum number of expectation at helper registration
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2026-06-23 22:16:12
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On helper registration, the maximum number of expectations cannot go over
NF_CT_EXPECT_MAX_CNT (255), but zero can be specified then
nf_conntrack_expect_max applies. Turn zero into NF_CT_EXPECT_MAX_CNT
otherwise, expectation LRU eviction on insertion is disabled.
Moreover, expand this sanity check all expectation classes.
This max_expecy policy is only tunable since userspace helpers are
available, set Fixes: tag to the commit that adds such infrastructure.
Remove the check for p->max_expected given this field must always
be non-zero after this patch.
Fixes: 12f7a505331e ("netfilter: add user-space connection tracking helper infrastructure")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nf_conntrack_expect.c | 3 +--
net/netfilter/nf_conntrack_helper.c | 9 +++++++--
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
index 113bb1cb1683..38630c5e006f 100644
--- a/net/netfilter/nf_conntrack_expect.c
+++ b/net/netfilter/nf_conntrack_expect.c@@ -496,8 +496,7 @@ static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect, lockdep_is_held(&nf_conntrack_expect_lock)); if (helper) { p = &helper->expect_policy[expect->class]; - if (p->max_expected && - master_help->expecting[expect->class] >= p->max_expected) + if (master_help->expecting[expect->class] >= p->max_expected) evict_oldest_expect(master_help, expect, p); } else { const struct nf_conntrack_expect_policy default_exp_policy = {
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 8b94001c2430..500509b17663 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c@@ -374,8 +374,13 @@ int __nf_conntrack_helper_register(struct nf_conntrack_helper *me) if (!nf_ct_helper_hash) return -ENOENT; - if (me->expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT) - return -EINVAL; + for (i = 0; i <= me->expect_class_max; i++) { + if (!me->expect_policy[i].max_expected) + me->expect_policy[i].max_expected = NF_CT_EXPECT_MAX_CNT; + + if (me->expect_policy[i].max_expected > NF_CT_EXPECT_MAX_CNT) + return -EINVAL; + } mutex_lock(&nf_ct_helper_mutex); for (i = 0; i < nf_ct_helper_hsize; i++) {
--
2.47.3