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, 204 insertions, 0 deletions

diff --git a/drivers/hid/hid-appletb-bl.c b/drivers/hid/hid-appletb-bl.c
new file mode 100644
index 000000000..bad2aead8
--- /dev/null
+++ b/drivers/hid/hid-appletb-bl.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple Touch Bar Backlight Driver
+ *
+ * Copyright (c) 2017-2018 Ronald Tschalär
+ * Copyright (c) 2022-2023 Kerem Karabay <kekrby@gmail.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hid.h>
+#include <linux/backlight.h>
+#include <linux/device.h>
+
+#include "hid-ids.h"
+
+#define APPLETB_BL_ON			1
+#define APPLETB_BL_DIM			3
+#define APPLETB_BL_OFF			4
+
+#define HID_UP_APPLEVENDOR_TB_BL	0xff120000
+
+#define HID_VD_APPLE_TB_BRIGHTNESS	0xff120001
+#define HID_USAGE_AUX1			0xff120020
+#define HID_USAGE_BRIGHTNESS		0xff120021
+
+static int appletb_bl_def_brightness = 2;
+module_param_named(brightness, appletb_bl_def_brightness, int, 0444);
+MODULE_PARM_DESC(brightness, "Default brightness:\n"
+			 "    0 - Touchbar is off\n"
+			 "    1 - Dim brightness\n"
+			 "    [2] - Full brightness");
+
+struct appletb_bl {
+	struct hid_field *aux1_field, *brightness_field;
+	struct backlight_device *bdev;
+
+	bool full_on;
+};
+
+static const u8 appletb_bl_brightness_map[] = {
+	APPLETB_BL_OFF,
+	APPLETB_BL_DIM,
+	APPLETB_BL_ON,
+};
+
+static int appletb_bl_set_brightness(struct appletb_bl *bl, u8 brightness)
+{
+	struct hid_report *report = bl->brightness_field->report;
+	struct hid_device *hdev = report->device;
+	int ret;
+
+	ret = hid_set_field(bl->aux1_field, 0, 1);
+	if (ret) {
+		hid_err(hdev, "Failed to set auxiliary field (%pe)\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	ret = hid_set_field(bl->brightness_field, 0, brightness);
+	if (ret) {
+		hid_err(hdev, "Failed to set brightness field (%pe)\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	if (!bl->full_on) {
+		ret = hid_hw_power(hdev, PM_HINT_FULLON);
+		if (ret < 0) {
+			hid_err(hdev, "Device didn't power on (%pe)\n", ERR_PTR(ret));
+			return ret;
+		}
+
+		bl->full_on = true;
+	}
+
+	hid_hw_request(hdev, report, HID_REQ_SET_REPORT);
+
+	if (brightness == APPLETB_BL_OFF) {
+		hid_hw_power(hdev, PM_HINT_NORMAL);
+		bl->full_on = false;
+	}
+
+	return 0;
+}
+
+static int appletb_bl_update_status(struct backlight_device *bdev)
+{
+	struct appletb_bl *bl = bl_get_data(bdev);
+	u8 brightness;
+
+	if (backlight_is_blank(bdev))
+		brightness = APPLETB_BL_OFF;
+	else
+		brightness = appletb_bl_brightness_map[backlight_get_brightness(bdev)];
+
+	return appletb_bl_set_brightness(bl, brightness);
+}
+
+static const struct backlight_ops appletb_bl_backlight_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = appletb_bl_update_status,
+};
+
+static int appletb_bl_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct hid_field *aux1_field, *brightness_field;
+	struct backlight_properties bl_props = { 0 };
+	struct device *dev = &hdev->dev;
+	struct appletb_bl *bl;
+	int ret;
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return dev_err_probe(dev, ret, "HID parse failed\n");
+
+	aux1_field = hid_find_field(hdev, HID_FEATURE_REPORT,
+				    HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_AUX1);
+
+	brightness_field = hid_find_field(hdev, HID_FEATURE_REPORT,
+					  HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_BRIGHTNESS);
+
+	if (!aux1_field || !brightness_field)
+		return -ENODEV;
+
+	if (aux1_field->report != brightness_field->report)
+		return dev_err_probe(dev, -ENODEV, "Encountered unexpected report structure\n");
+
+	bl = devm_kzalloc(dev, sizeof(*bl), GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
+	if (ret)
+		return dev_err_probe(dev, ret, "HID hardware start failed\n");
+
+	ret = hid_hw_open(hdev);
+	if (ret) {
+		dev_err_probe(dev, ret, "HID hardware open failed\n");
+		goto stop_hw;
+	}
+
+	bl->aux1_field = aux1_field;
+	bl->brightness_field = brightness_field;
+
+	ret = appletb_bl_set_brightness(bl,
+		appletb_bl_brightness_map[(appletb_bl_def_brightness > 2) ? 2 : appletb_bl_def_brightness]);
+
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to set default touch bar brightness to %d\n",
+			      appletb_bl_def_brightness);
+		goto close_hw;
+	}
+
+	bl_props.type = BACKLIGHT_RAW;
+	bl_props.max_brightness = ARRAY_SIZE(appletb_bl_brightness_map) - 1;
+
+	bl->bdev = devm_backlight_device_register(dev, "appletb_backlight", dev, bl,
+						  &appletb_bl_backlight_ops, &bl_props);
+	if (IS_ERR(bl->bdev)) {
+		ret = PTR_ERR(bl->bdev);
+		dev_err_probe(dev, ret, "Failed to register backlight device\n");
+		goto close_hw;
+	}
+
+	hid_set_drvdata(hdev, bl);
+
+	return 0;
+
+close_hw:
+	hid_hw_close(hdev);
+stop_hw:
+	hid_hw_stop(hdev);
+
+	return ret;
+}
+
+static void appletb_bl_remove(struct hid_device *hdev)
+{
+	struct appletb_bl *bl = hid_get_drvdata(hdev);
+
+	appletb_bl_set_brightness(bl, APPLETB_BL_OFF);
+
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id appletb_bl_hid_ids[] = {
+	/* MacBook Pro's 2018, 2019, with T2 chip: iBridge DFR Brightness */
+	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, appletb_bl_hid_ids);
+
+static struct hid_driver appletb_bl_hid_driver = {
+	.name = "hid-appletb-bl",
+	.id_table = appletb_bl_hid_ids,
+	.probe = appletb_bl_probe,
+	.remove = appletb_bl_remove,
+};
+module_hid_driver(appletb_bl_hid_driver);
+
+MODULE_AUTHOR("Ronald Tschalär");
+MODULE_AUTHOR("Kerem Karabay <kekrby@gmail.com>");
+MODULE_DESCRIPTION("MacBook Pro Touch Bar Backlight driver");
+MODULE_LICENSE("GPL");