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, 71 insertions, 0 deletions

diff --git a/net/dsa/user.h b/net/dsa/user.h
new file mode 100644
index 000000000..016884bea
--- /dev/null
+++ b/net/dsa/user.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __DSA_USER_H
+#define __DSA_USER_H
+
+#include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
+#include <linux/list.h>
+#include <linux/netpoll.h>
+#include <linux/types.h>
+#include <net/dsa.h>
+#include <net/gro_cells.h>
+
+struct net_device;
+struct netlink_ext_ack;
+
+extern struct notifier_block dsa_user_switchdev_notifier;
+extern struct notifier_block dsa_user_switchdev_blocking_notifier;
+
+struct dsa_user_priv {
+	/* Copy of CPU port xmit for faster access in user transmit hot path */
+	struct sk_buff *	(*xmit)(struct sk_buff *skb,
+					struct net_device *dev);
+
+	struct gro_cells	gcells;
+
+	/* DSA port data, such as switch, port index, etc. */
+	struct dsa_port		*dp;
+
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	struct netpoll		*netpoll;
+#endif
+
+	/* TC context */
+	struct list_head	mall_tc_list;
+};
+
+void dsa_user_mii_bus_init(struct dsa_switch *ds);
+int dsa_user_create(struct dsa_port *dp);
+void dsa_user_destroy(struct net_device *user_dev);
+int dsa_user_suspend(struct net_device *user_dev);
+int dsa_user_resume(struct net_device *user_dev);
+int dsa_user_register_notifier(void);
+void dsa_user_unregister_notifier(void);
+int dsa_user_host_uc_install(struct net_device *dev, const u8 *addr);
+void dsa_user_host_uc_uninstall(struct net_device *dev);
+void dsa_user_sync_ha(struct net_device *dev);
+void dsa_user_unsync_ha(struct net_device *dev);
+void dsa_user_setup_tagger(struct net_device *user);
+int dsa_user_change_mtu(struct net_device *dev, int new_mtu);
+int dsa_user_change_conduit(struct net_device *dev, struct net_device *conduit,
+			    struct netlink_ext_ack *extack);
+int dsa_user_manage_vlan_filtering(struct net_device *dev,
+				   bool vlan_filtering);
+
+static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
+{
+	struct dsa_user_priv *p = netdev_priv(dev);
+
+	return p->dp;
+}
+
+static inline struct net_device *
+dsa_user_to_conduit(const struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_user_to_port(dev);
+
+	return dsa_port_to_conduit(dp);
+}
+
+#endif