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, 63 insertions, 0 deletions

diff --git a/include/net/llc_if.h b/include/net/llc_if.h
new file mode 100644
index 000000000..a33325961
--- /dev/null
+++ b/include/net/llc_if.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LLC_IF_H
+#define LLC_IF_H
+/*
+ * Copyright (c) 1997 by Procom Technology,Inc.
+ * 		 2001 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+/* Defines LLC interface to network layer */
+/* Available primitives */
+#include <linux/if.h>
+#include <linux/if_arp.h>
+#include <linux/llc.h>
+#include <linux/etherdevice.h>
+#include <net/llc.h>
+
+#define LLC_DATAUNIT_PRIM	1
+#define LLC_CONN_PRIM		2
+#define LLC_DATA_PRIM		3
+#define LLC_DISC_PRIM		4
+#define LLC_RESET_PRIM		5
+#define LLC_FLOWCONTROL_PRIM	6 /* Not supported at this time */
+#define LLC_DISABLE_PRIM	7
+#define LLC_XID_PRIM		8
+#define LLC_TEST_PRIM		9
+#define LLC_SAP_ACTIVATION     10
+#define LLC_SAP_DEACTIVATION   11
+
+#define LLC_NBR_PRIMITIVES     11
+
+#define LLC_IND			1
+#define LLC_CONFIRM		2
+
+/* Primitive type */
+#define LLC_PRIM_TYPE_REQ	1
+#define LLC_PRIM_TYPE_IND	2
+#define LLC_PRIM_TYPE_RESP	3
+#define LLC_PRIM_TYPE_CONFIRM	4
+
+/* Reset reasons, remote entity or local LLC */
+#define LLC_RESET_REASON_REMOTE	1
+#define LLC_RESET_REASON_LOCAL	2
+
+/* Disconnect reasons */
+#define LLC_DISC_REASON_RX_DM_RSP_PDU	0
+#define LLC_DISC_REASON_RX_DISC_CMD_PDU	1
+#define LLC_DISC_REASON_ACK_TMR_EXP	2
+
+/* Confirm reasons */
+#define LLC_STATUS_CONN		0 /* connect confirm & reset confirm */
+#define LLC_STATUS_DISC		1 /* connect confirm & reset confirm */
+#define LLC_STATUS_FAILED	2 /* connect confirm & reset confirm */
+#define LLC_STATUS_IMPOSSIBLE	3 /* connect confirm */
+#define LLC_STATUS_RECEIVED	4 /* data conn */
+#define LLC_STATUS_REMOTE_BUSY	5 /* data conn */
+#define LLC_STATUS_REFUSE	6 /* data conn */
+#define LLC_STATUS_CONFLICT	7 /* disconnect conn */
+#define LLC_STATUS_RESET_DONE	8 /*  */
+
+int llc_establish_connection(struct sock *sk, const u8 *lmac, u8 *dmac,
+			     u8 dsap);
+int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb);
+int llc_send_disc(struct sock *sk);
+#endif /* LLC_IF_H */