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, 77 insertions, 0 deletions

diff --git a/include/net/calipso.h b/include/net/calipso.h
new file mode 100644
index 000000000..76b9e08c1
--- /dev/null
+++ b/include/net/calipso.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * CALIPSO - Common Architecture Label IPv6 Security Option
+ *
+ * This is an implementation of the CALIPSO protocol as specified in
+ * RFC 5570.
+ *
+ * Authors: Paul Moore <paul@paul-moore.com>
+ *          Huw Davies <huw@codeweavers.com>
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ * (c) Copyright Huw Davies <huw@codeweavers.com>, 2015
+ */
+
+#ifndef _CALIPSO_H
+#define _CALIPSO_H
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <net/netlabel.h>
+#include <net/request_sock.h>
+#include <linux/refcount.h>
+#include <linux/unaligned.h>
+
+/* known doi values */
+#define CALIPSO_DOI_UNKNOWN          0x00000000
+
+/* doi mapping types */
+#define CALIPSO_MAP_UNKNOWN          0
+#define CALIPSO_MAP_PASS             2
+
+/*
+ * CALIPSO DOI definitions
+ */
+
+/* DOI definition struct */
+struct calipso_doi {
+	u32 doi;
+	u32 type;
+
+	refcount_t refcount;
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+/*
+ * Sysctl Variables
+ */
+extern int calipso_cache_enabled;
+extern int calipso_cache_bucketsize;
+
+#ifdef CONFIG_NETLABEL
+int __init calipso_init(void);
+void calipso_exit(void);
+bool calipso_validate(const struct sk_buff *skb, const unsigned char *option);
+#else
+static inline int __init calipso_init(void)
+{
+	return 0;
+}
+
+static inline void calipso_exit(void)
+{
+}
+static inline bool calipso_validate(const struct sk_buff *skb,
+				    const unsigned char *option)
+{
+	return true;
+}
+#endif /* CONFIG_NETLABEL */
+
+#endif /* _CALIPSO_H */