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@chromium.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
+#include <linux/capability.h>
#include <net/netlink.h>
#include <net/sock.h>
struct nfnl_cthelper *nlcth;
int ret = 0;
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
return -EINVAL;
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,
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]);