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, 23 insertions, 0 deletions

diff --git a/security/selinux/include/conditional.h b/security/selinux/include/conditional.h
new file mode 100644
index 000000000..060833e2d
--- /dev/null
+++ b/security/selinux/include/conditional.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Interface to booleans in the security server. This is exported
+ * for the selinuxfs.
+ *
+ * Author: Karl MacMillan <kmacmillan@tresys.com>
+ *
+ * Copyright (C) 2003 - 2004 Tresys Technology, LLC
+ */
+
+#ifndef _SELINUX_CONDITIONAL_H_
+#define _SELINUX_CONDITIONAL_H_
+
+#include "security.h"
+
+int security_get_bools(struct selinux_policy *policy, u32 *len, char ***names,
+		       int **values);
+
+int security_set_bools(u32 len, const int *values);
+
+int security_get_bool_value(u32 index);
+
+#endif