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authorFlorian Westphal <fw@strlen.de>2022-02-02 12:00:56 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2022-02-04 05:39:57 +0100
commitd1ca60efc53d665cf89ed847a14a510a81770b81 (patch)
treebfc6a9d7bf7cd19a341a9a24396607c1e11eb3f1 /net
parent1f6339e034d5780ad7097c8d8c11b26e0762afba (diff)
netfilter: ctnetlink: disable helper autoassign
When userspace, e.g. conntrackd, inserts an entry with a specified helper, its possible that the helper is lost immediately after its added: ctnetlink_create_conntrack -> nf_ct_helper_ext_add + assign helper -> ctnetlink_setup_nat -> ctnetlink_parse_nat_setup -> parse_nat_setup -> nfnetlink_parse_nat_setup -> nf_nat_setup_info -> nf_conntrack_alter_reply -> __nf_ct_try_assign_helper ... and __nf_ct_try_assign_helper will zero the helper again. Set IPS_HELPER bit to bypass auto-assign logic, its unwanted, just like when helper is assigned via ruleset. Dropped old 'not strictly necessary' comment, it referred to use of rcu_assign_pointer() before it got replaced by RCU_INIT_POINTER(). NB: Fixes tag intentionally incorrect, this extends the referenced commit, but this change won't build without IPS_HELPER introduced there. Fixes: 6714cf5465d280 ("netfilter: nf_conntrack: fix explicit helper attachment and NAT") Reported-by: Pham Thanh Tuyen <phamtyn@gmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_conntrack_netlink.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index ac438370f94a..7032402ffd33 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2311,7 +2311,8 @@ ctnetlink_create_conntrack(struct net *net,
if (helper->from_nlattr)
helper->from_nlattr(helpinfo, ct);
- /* not in hash table yet so not strictly necessary */
+ /* disable helper auto-assignment for this entry */
+ ct->status |= IPS_HELPER;
RCU_INIT_POINTER(help->helper, helper);
}
} else {