From: Jonathon Reinhart jonathon.reinhart@gmail.com
commit 2671fa4dc0109d3fb581bc3078fdf17b5d9080f6 upstream.
These sysctls point to global variables: - NF_SYSCTL_CT_MAX (&nf_conntrack_max) - NF_SYSCTL_CT_EXPECT_MAX (&nf_ct_expect_max) - NF_SYSCTL_CT_BUCKETS (&nf_conntrack_htable_size_user)
Because their data pointers are not updated to point to per-netns structures, they must be marked read-only in a non-init_net ns. Otherwise, changes in any net namespace are reflected in (leaked into) all other net namespaces. This problem has existed since the introduction of net namespaces.
The current logic marks them read-only only if the net namespace is owned by an unprivileged user (other than init_user_ns).
Commit d0febd81ae77 ("netfilter: conntrack: re-visit sysctls in unprivileged namespaces") "exposes all sysctls even if the namespace is unpriviliged." Since we need to mark them readonly in any case, we can forego the unprivileged user check altogether.
Fixes: d0febd81ae77 ("netfilter: conntrack: re-visit sysctls in unprivileged namespaces") Signed-off-by: Jonathon Reinhart Jonathon.Reinhart@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_conntrack_standalone.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
--- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -1060,16 +1060,10 @@ static int nf_conntrack_standalone_init_ nf_conntrack_standalone_init_dccp_sysctl(net, table); nf_conntrack_standalone_init_gre_sysctl(net, table);
- /* Don't allow unprivileged users to alter certain sysctls */ - if (net->user_ns != &init_user_ns) { + /* Don't allow non-init_net ns to alter global sysctls */ + if (!net_eq(&init_net, net)) { table[NF_SYSCTL_CT_MAX].mode = 0444; table[NF_SYSCTL_CT_EXPECT_MAX].mode = 0444; - table[NF_SYSCTL_CT_HELPER].mode = 0444; -#ifdef CONFIG_NF_CONNTRACK_EVENTS - table[NF_SYSCTL_CT_EVENTS].mode = 0444; -#endif - table[NF_SYSCTL_CT_BUCKETS].mode = 0444; - } else if (!net_eq(&init_net, net)) { table[NF_SYSCTL_CT_BUCKETS].mode = 0444; }