From: Florian Westphal fw@strlen.de
[ 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@gmail.com Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/uapi/linux/netfilter/nf_conntrack_common.h | 2 +- net/netfilter/nf_conntrack_netlink.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-)
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 {