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, 49 insertions, 0 deletions

diff --git a/net/netlabel/netlabel_user.h b/net/netlabel/netlabel_user.h
new file mode 100644
index 000000000..d4c434956
--- /dev/null
+++ b/net/netlabel/netlabel_user.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * NetLabel NETLINK Interface
+ *
+ * This file defines the NETLINK interface for the NetLabel system.  The
+ * NetLabel system manages static and dynamic label mappings for network
+ * protocols such as CIPSO and RIPSO.
+ *
+ * Author: Paul Moore <paul@paul-moore.com>
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ */
+
+#ifndef _NETLABEL_USER_H
+#define _NETLABEL_USER_H
+
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/capability.h>
+#include <linux/audit.h>
+#include <net/netlink.h>
+#include <net/genetlink.h>
+#include <net/netlabel.h>
+
+/* NetLabel NETLINK helper functions */
+
+/**
+ * netlbl_netlink_auditinfo - Fetch the audit information from a NETLINK msg
+ * @audit_info: NetLabel audit information
+ */
+static inline void netlbl_netlink_auditinfo(struct netlbl_audit *audit_info)
+{
+	security_current_getlsmprop_subj(&audit_info->prop);
+	audit_info->loginuid = audit_get_loginuid(current);
+	audit_info->sessionid = audit_get_sessionid(current);
+}
+
+/* NetLabel NETLINK I/O functions */
+
+int netlbl_netlink_init(void);
+
+/* NetLabel Audit Functions */
+
+struct audit_buffer *netlbl_audit_start_common(int type,
+					      struct netlbl_audit *audit_info);
+
+#endif