openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/net/openvswitch/vport-gre.c b/net/openvswitch/vport-gre.c
new file mode 100644
index 000000000..6cb5a697b
--- /dev/null
+++ b/net/openvswitch/vport-gre.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2007-2014 Nicira, Inc.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/if.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/if_tunnel.h>
+#include <linux/if_vlan.h>
+#include <linux/in.h>
+#include <linux/in_route.h>
+#include <linux/inetdevice.h>
+#include <linux/jhash.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/rculist.h>
+#include <net/route.h>
+#include <net/xfrm.h>
+
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/ip_tunnels.h>
+#include <net/gre.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/protocol.h>
+
+#include "datapath.h"
+#include "vport.h"
+#include "vport-netdev.h"
+
+static struct vport_ops ovs_gre_vport_ops;
+
+static struct vport *gre_tnl_create(const struct vport_parms *parms)
+{
+	struct net *net = ovs_dp_get_net(parms->dp);
+	struct net_device *dev;
+	struct vport *vport;
+	int err;
+
+	vport = ovs_vport_alloc(0, &ovs_gre_vport_ops, parms);
+	if (IS_ERR(vport))
+		return vport;
+
+	rtnl_lock();
+	dev = gretap_fb_dev_create(net, parms->name, NET_NAME_USER);
+	if (IS_ERR(dev)) {
+		rtnl_unlock();
+		ovs_vport_free(vport);
+		return ERR_CAST(dev);
+	}
+
+	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
+	if (err < 0) {
+		rtnl_delete_link(dev, 0, NULL);
+		rtnl_unlock();
+		ovs_vport_free(vport);
+		return ERR_PTR(err);
+	}
+
+	vport->dev = dev;
+	netdev_hold(vport->dev, &vport->dev_tracker, GFP_KERNEL);
+
+	rtnl_unlock();
+	return vport;
+}
+
+static struct vport *gre_create(const struct vport_parms *parms)
+{
+	struct vport *vport;
+
+	vport = gre_tnl_create(parms);
+	if (IS_ERR(vport))
+		return vport;
+
+	return ovs_netdev_link(vport, true);
+}
+
+static struct vport_ops ovs_gre_vport_ops = {
+	.type		= OVS_VPORT_TYPE_GRE,
+	.create		= gre_create,
+	.send		= dev_queue_xmit,
+	.destroy	= ovs_netdev_tunnel_destroy,
+};
+
+static int __init ovs_gre_tnl_init(void)
+{
+	return ovs_vport_ops_register(&ovs_gre_vport_ops);
+}
+
+static void __exit ovs_gre_tnl_exit(void)
+{
+	ovs_vport_ops_unregister(&ovs_gre_vport_ops);
+}
+
+module_init(ovs_gre_tnl_init);
+module_exit(ovs_gre_tnl_exit);
+
+MODULE_DESCRIPTION("OVS: GRE switching port");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("vport-type-3");