60 lines
1.7 KiB
Diff
60 lines
1.7 KiB
Diff
From 2af0d441c8b1151a5d8bb46ec9c58ab575fe7d6f Mon Sep 17 00:00:00 2001
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From: Kevin Cernekee <cernekee@chromium.org>
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Date: Tue, 5 Dec 2017 15:42:41 -0800
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Subject: [PATCH] netfilter: xt_osf: Add missing permission checks
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The capability check in nfnetlink_rcv() verifies that the caller
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has CAP_NET_ADMIN in the namespace that "owns" the netlink socket.
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However, xt_osf_fingers is shared by all net namespaces on the
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system. An unprivileged user can create user and net namespaces
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in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable()
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check:
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vpnns -- nfnl_osf -f /tmp/pf.os
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vpnns -- nfnl_osf -f /tmp/pf.os -d
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These non-root operations successfully modify the systemwide OS
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fingerprint list. Add new capable() checks so that they can't.
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Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
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---
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net/netfilter/xt_osf.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c
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index 36e14b1f061d..a34f314a8c23 100644
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--- a/net/netfilter/xt_osf.c
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+++ b/net/netfilter/xt_osf.c
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@@ -19,6 +19,7 @@
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#include <linux/module.h>
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#include <linux/kernel.h>
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+#include <linux/capability.h>
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#include <linux/if.h>
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#include <linux/inetdevice.h>
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#include <linux/ip.h>
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@@ -70,6 +71,9 @@ static int xt_osf_add_callback(struct net *net, struct sock *ctnl,
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struct xt_osf_finger *kf = NULL, *sf;
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int err = 0;
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+ if (!capable(CAP_NET_ADMIN))
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+ return -EPERM;
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+
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if (!osf_attrs[OSF_ATTR_FINGER])
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return -EINVAL;
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@@ -115,6 +119,9 @@ static int xt_osf_remove_callback(struct net *net, struct sock *ctnl,
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struct xt_osf_finger *sf;
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int err = -ENOENT;
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+ if (!capable(CAP_NET_ADMIN))
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+ return -EPERM;
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+
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if (!osf_attrs[OSF_ATTR_FINGER])
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return -EINVAL;
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--
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2.14.3
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