This is a note to let you know that I've just added the patch titled
netfilter: nfnetlink_cthelper: Add missing permission checks
to the 4.9-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-nfnetlink_cthelper-add-missing-permission-checks.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4b380c42f7d00a395feede754f0bc2292eebe6e5 Mon Sep 17 00:00:00 2001
From: Kevin Cernekee <cernekee@xxxxxxxxxxxx>
Date: Sun, 3 Dec 2017 12:12:45 -0800
Subject: netfilter: nfnetlink_cthelper: Add missing permission checks
From: Kevin Cernekee <cernekee@xxxxxxxxxxxx>
commit 4b380c42f7d00a395feede754f0bc2292eebe6e5 upstream.
The capability check in nfnetlink_rcv() verifies that the caller
has CAP_NET_ADMIN in the namespace that "owns" the netlink socket.
However, nfnl_cthelper_list is shared by all net namespaces on the
system. An unprivileged user can create user and net namespaces
in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable()
check:
$ nfct helper list
nfct v1.4.4: netlink error: Operation not permitted
$ vpnns -- nfct helper list
{
.name = ftp,
.queuenum = 0,
.l3protonum = 2,
.l4protonum = 6,
.priv_data_len = 24,
.status = enabled,
};
Add capable() checks in nfnetlink_cthelper, as this is cleaner than
trying to generalize the solution.
Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Acked-by: Michal Kubecek <mkubecek@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netfilter/nfnetlink_cthelper.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/net/netfilter/nfnetlink_cthelper.c
+++ b/net/netfilter/nfnetlink_cthelper.c
@@ -17,6 +17,7 @@
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
+#include <linux/capability.h>
#include <net/netlink.h>
#include <net/sock.h>
@@ -392,6 +393,9 @@ static int nfnl_cthelper_new(struct net
struct nfnl_cthelper *nlcth;
int ret = 0;
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
return -EINVAL;
@@ -595,6 +599,9 @@ static int nfnl_cthelper_get(struct net
struct nfnl_cthelper *nlcth;
bool tuple_set = false;
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
if (nlh->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
.dump = nfnl_cthelper_dump_table,
@@ -661,6 +668,9 @@ static int nfnl_cthelper_del(struct net
struct nfnl_cthelper *nlcth, *n;
int j = 0, ret;
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
if (tb[NFCTH_NAME])
helper_name = nla_data(tb[NFCTH_NAME]);
Patches currently in stable-queue which might be from cernekee@xxxxxxxxxxxx are
queue-4.9/netfilter-xt_osf-add-missing-permission-checks.patch
queue-4.9/netfilter-nfnetlink_cthelper-add-missing-permission-checks.patch