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, 79 insertions, 0 deletions

diff --git a/include/soc/qcom/tcs.h b/include/soc/qcom/tcs.h
new file mode 100644
index 000000000..cff67ce25
--- /dev/null
+++ b/include/soc/qcom/tcs.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2016-2019, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef __SOC_QCOM_TCS_H__
+#define __SOC_QCOM_TCS_H__
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+
+#define MAX_RPMH_PAYLOAD	16
+
+/**
+ * rpmh_state: state for the request
+ *
+ * RPMH_SLEEP_STATE:       State of the resource when the processor subsystem
+ *                         is powered down. There is no client using the
+ *                         resource actively.
+ * RPMH_WAKE_ONLY_STATE:   Resume resource state to the value previously
+ *                         requested before the processor was powered down.
+ * RPMH_ACTIVE_ONLY_STATE: Active or AMC mode requests. Resource state
+ *                         is aggregated immediately.
+ */
+enum rpmh_state {
+	RPMH_SLEEP_STATE,
+	RPMH_WAKE_ONLY_STATE,
+	RPMH_ACTIVE_ONLY_STATE,
+};
+
+/**
+ * struct tcs_cmd: an individual request to RPMH.
+ *
+ * @addr: the address of the resource slv_id:18:16 | offset:0:15
+ * @data: the resource state request
+ * @wait: ensure that this command is complete before returning.
+ *        Setting "wait" here only makes sense during rpmh_write_batch() for
+ *        active-only transfers, this is because:
+ *        rpmh_write() - Always waits.
+ *                       (DEFINE_RPMH_MSG_ONSTACK will set .wait_for_compl)
+ *        rpmh_write_async() - Never waits.
+ *                       (There's no request completion callback)
+ */
+struct tcs_cmd {
+	u32 addr;
+	u32 data;
+	u32 wait;
+};
+
+/**
+ * struct tcs_request: A set of tcs_cmds sent together in a TCS
+ *
+ * @state:          state for the request.
+ * @wait_for_compl: wait until we get a response from the h/w accelerator
+ *                  (same as setting cmd->wait for all commands in the request)
+ * @num_cmds:       the number of @cmds in this request
+ * @cmds:           an array of tcs_cmds
+ */
+struct tcs_request {
+	enum rpmh_state state;
+	u32 wait_for_compl;
+	u32 num_cmds;
+	struct tcs_cmd *cmds;
+};
+
+#define BCM_TCS_CMD_COMMIT_MASK		BIT(30)
+#define BCM_TCS_CMD_VALID_MASK		BIT(29)
+#define BCM_TCS_CMD_VOTE_MASK		GENMASK(13, 0)
+#define BCM_TCS_CMD_VOTE_Y_MASK		GENMASK(13, 0)
+#define BCM_TCS_CMD_VOTE_X_MASK		GENMASK(27, 14)
+
+/* Construct a Bus Clock Manager (BCM) specific TCS command */
+#define BCM_TCS_CMD(commit, valid, vote_x, vote_y)		\
+	(u32_encode_bits(commit, BCM_TCS_CMD_COMMIT_MASK) |	\
+	u32_encode_bits(valid, BCM_TCS_CMD_VALID_MASK) |	\
+	u32_encode_bits(vote_x, BCM_TCS_CMD_VOTE_X_MASK) |	\
+	u32_encode_bits(vote_y, BCM_TCS_CMD_VOTE_Y_MASK))
+
+#endif /* __SOC_QCOM_TCS_H__ */