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 {