summaryrefslogtreecommitdiffstats
path: root/drivers/media/rc/bpf-lirc.c
blob: 390a722e6211320cd59764ac9de5cf8ff8cad9d6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
// SPDX-License-Identifier: GPL-2.0
// bpf-lirc.c - handles bpf
//
// Copyright (C) 2018 Sean Young <sean@mess.org>

#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/bpf_lirc.h>
#include "rc-core-priv.h"

/*
 * BPF interface for raw IR
 */
const struct bpf_prog_ops lirc_mode2_prog_ops = {
};

BPF_CALL_1(bpf_rc_repeat, u32*, sample)
{
	struct ir_raw_event_ctrl *ctrl;

	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);

	rc_repeat(ctrl->dev);

	return 0;
}

static const struct bpf_func_proto rc_repeat_proto = {
	.func	   = bpf_rc_repeat,
	.gpl_only  = true, /* rc_repeat is EXPORT_SYMBOL_GPL */
	.ret_type  = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_CTX,
};

/*
 * Currently rc-core does not support 64-bit scancodes, but there are many
 * known protocols with more than 32 bits. So, define the interface as u64
 * as a future-proof.
 */
BPF_CALL_4(bpf_rc_keydown, u32*, sample, u32, protocol, u64, scancode,
	   u32, toggle)
{
	struct ir_raw_event_ctrl *ctrl;

	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);

	rc_keydown(ctrl->dev, protocol, scancode, toggle != 0);

	return 0;
}

static const struct bpf_func_proto rc_keydown_proto = {
	.func	   = bpf_rc_keydown,
	.gpl_only  = true, /* rc_keydown is EXPORT_SYMBOL_GPL */
	.ret_type  = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_CTX,
	.arg2_type = ARG_ANYTHING,
	.arg3_type = ARG_ANYTHING,
	.arg4_type = ARG_ANYTHING,
};

BPF_CALL_3(bpf_rc_pointer_rel, u32*, sample, s32, rel_x, s32, rel_y)
{
	struct ir_raw_event_ctrl *ctrl;

	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);

	input_report_rel(ctrl->dev->input_dev, REL_X, rel_x);
	input_report_rel(ctrl->dev->input_dev, REL_Y, rel_y);
	input_sync(ctrl->dev->input_dev);

	return 0;
}

static const struct bpf_func_proto rc_pointer_rel_proto = {
	.func	   = bpf_rc_pointer_rel,
	.gpl_only  = true,
	.ret_type  = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_CTX,
	.arg2_type = ARG_ANYTHING,
	.arg3_type = ARG_ANYTHING,
};

static const struct bpf_func_proto *
lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
	switch (func_id) {
	case BPF_FUNC_rc_repeat:
		return &rc_repeat_proto;
	case BPF_FUNC_rc_keydown:
		return &rc_keydown_proto;
	case BPF_FUNC_rc_pointer_rel:
		return &rc_pointer_rel_proto;
	case BPF_FUNC_map_lookup_elem:
		return &bpf_map_lookup_elem_proto;
	case BPF_FUNC_map_update_elem:
		return &bpf_map_update_elem_proto;
	case BPF_FUNC_map_delete_elem:
		return &bpf_map_delete_elem_proto;
	case BPF_FUNC_ktime_get_ns:
		return &bpf_ktime_get_ns_proto;
	case BPF_FUNC_tail_call:
		return &bpf_tail_call_proto;
	case BPF_FUNC_get_prandom_u32:
		return &bpf_get_prandom_u32_proto;
	case BPF_FUNC_trace_printk:
		if (capable(CAP_SYS_ADMIN))
			return bpf_get_trace_printk_proto();
		/* fall through */
	default:
		return NULL;
	}
}

static bool lirc_mode2_is_valid_access(int off, int size,
				       enum bpf_access_type type,
				       const struct bpf_prog *prog,
				       struct bpf_insn_access_aux *info)
{
	/* We have one field of u32 */
	return type == BPF_READ && off == 0 && size == sizeof(u32);
}

const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
	.get_func_proto  = lirc_mode2_func_proto,
	.is_valid_access = lirc_mode2_is_valid_access
};

#define BPF_MAX_PROGS 64

static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
	struct bpf_prog_array __rcu *old_array;
	struct bpf_prog_array *new_array;
	struct ir_raw_event_ctrl *raw;
	int ret;

	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
		return -EINVAL;

	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
	if (ret)
		return ret;

	raw = rcdev->raw;
	if (!raw) {
		ret = -ENODEV;
		goto unlock;
	}

	if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
		ret = -E2BIG;
		goto unlock;
	}

	old_array = raw->progs;
	ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
	if (ret < 0)
		goto unlock;

	rcu_assign_pointer(raw->progs, new_array);
	bpf_prog_array_free(old_array);

unlock:
	mutex_unlock(&ir_raw_handler_lock);
	return ret;
}

static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
	struct bpf_prog_array __rcu *old_array;
	struct bpf_prog_array *new_array;
	struct ir_raw_event_ctrl *raw;
	int ret;

	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
		return -EINVAL;

	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
	if (ret)
		return ret;

	raw = rcdev->raw;
	if (!raw) {
		ret = -ENODEV;
		goto unlock;
	}

	old_array = raw->progs;
	ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
	/*
	 * Do not use bpf_prog_array_delete_safe() as we would end up
	 * with a dummy entry in the array, and the we would free the
	 * dummy in lirc_bpf_free()
	 */
	if (ret)
		goto unlock;

	rcu_assign_pointer(raw->progs, new_array);
	bpf_prog_array_free(old_array);
	bpf_prog_put(prog);
unlock:
	mutex_unlock(&ir_raw_handler_lock);
	return ret;
}

void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
{
	struct ir_raw_event_ctrl *raw = rcdev->raw;

	raw->bpf_sample = sample;

	if (raw->progs)
		BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN);
}

/*
 * This should be called once the rc thread has been stopped, so there can be
 * no concurrent bpf execution.
 */
void lirc_bpf_free(struct rc_dev *rcdev)
{
	struct bpf_prog_array_item *item;

	if (!rcdev->raw->progs)
		return;

	item = rcu_dereference(rcdev->raw->progs)->items;
	while (item->prog) {
		bpf_prog_put(item->prog);
		item++;
	}

	bpf_prog_array_free(rcdev->raw->progs);
}

int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
	struct rc_dev *rcdev;
	int ret;

	if (attr->attach_flags)
		return -EINVAL;

	rcdev = rc_dev_get_from_fd(attr->target_fd);
	if (IS_ERR(rcdev))
		return PTR_ERR(rcdev);

	ret = lirc_bpf_attach(rcdev, prog);

	put_device(&rcdev->dev);

	return ret;
}

int lirc_prog_detach(const union bpf_attr *attr)
{
	struct bpf_prog *prog;
	struct rc_dev *rcdev;
	int ret;

	if (attr->attach_flags)
		return -EINVAL;

	prog = bpf_prog_get_type(attr->attach_bpf_fd,
				 BPF_PROG_TYPE_LIRC_MODE2);
	if (IS_ERR(prog))
		return PTR_ERR(prog);

	rcdev = rc_dev_get_from_fd(attr->target_fd);
	if (IS_ERR(rcdev)) {
		bpf_prog_put(prog);
		return PTR_ERR(rcdev);
	}

	ret = lirc_bpf_detach(rcdev, prog);

	bpf_prog_put(prog);
	put_device(&rcdev->dev);

	return ret;
}

int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
{
	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
	struct bpf_prog_array __rcu *progs;
	struct rc_dev *rcdev;
	u32 cnt, flags = 0;
	int ret;

	if (attr->query.query_flags)
		return -EINVAL;

	rcdev = rc_dev_get_from_fd(attr->query.target_fd);
	if (IS_ERR(rcdev))
		return PTR_ERR(rcdev);

	if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
		ret = -EINVAL;
		goto put;
	}

	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
	if (ret)
		goto put;

	progs = rcdev->raw->progs;
	cnt = progs ? bpf_prog_array_length(progs) : 0;

	if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
		ret = -EFAULT;
		goto unlock;
	}

	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
		ret = -EFAULT;
		goto unlock;
	}

	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
		ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);

unlock:
	mutex_unlock(&ir_raw_handler_lock);
put:
	put_device(&rcdev->dev);

	return ret;
}