This is a note to let you know that I've just added the patch titled
netfilter: ctnetlink: disable helper autoassign
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-ctnetlink-disable-helper-autoassign.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6e18b8978fc67369a98f2e73e4f21cfa7cc9dd61
Author: Florian Westphal <fw@xxxxxxxxx>
Date: Wed Feb 2 12:00:56 2022 +0100
netfilter: ctnetlink: disable helper autoassign
[ Upstream commit d1ca60efc53d665cf89ed847a14a510a81770b81 ]
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@xxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/uapi/linux/netfilter/nf_conntrack_common.h b/include/uapi/linux/netfilter/nf_conntrack_common.h
index 4b3395082d15c..26071021e986f 100644
--- a/include/uapi/linux/netfilter/nf_conntrack_common.h
+++ b/include/uapi/linux/netfilter/nf_conntrack_common.h
@@ -106,7 +106,7 @@ enum ip_conntrack_status {
IPS_NAT_CLASH = IPS_UNTRACKED,
#endif
- /* Conntrack got a helper explicitly attached via CT target. */
+ /* Conntrack got a helper explicitly attached (ruleset, ctnetlink). */
IPS_HELPER_BIT = 13,
IPS_HELPER = (1 << IPS_HELPER_BIT),
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index c6bcc28ae3387..eeeaa34b3e7b5 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -2283,7 +2283,8 @@ 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 {
