75 lines
2.2 KiB
Diff
75 lines
2.2 KiB
Diff
From: Kevin Cernekee <cernekee@chromium.org>
|
|
Date: Sun, 3 Dec 2017 12:12:45 -0800
|
|
Subject: netfilter: nfnetlink_cthelper: Add missing permission checks
|
|
Origin: https://git.kernel.org/linus/4b380c42f7d00a395feede754f0bc2292eebe6e5
|
|
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-17448
|
|
|
|
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>
|
|
---
|
|
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>
|
|
|
|
@@ -407,6 +408,9 @@ 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;
|
|
|
|
@@ -611,6 +615,9 @@ 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,
|
|
@@ -678,6 +685,9 @@ 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]);
|
|
|