1// SPDX-License-Identifier: GPL-2.0
2// bpf-lirc.c - handles bpf
3//
4// Copyright (C) 2018 Sean Young <sean@mess.org>
5
6#include <linux/bpf.h>
7#include <linux/filter.h>
8#include <linux/bpf_lirc.h>
9#include "rc-core-priv.h"
10
11#define lirc_rcu_dereference(p)						\
12	rcu_dereference_protected(p, lockdep_is_held(&ir_raw_handler_lock))
13
14/*
15 * BPF interface for raw IR
16 */
17const struct bpf_prog_ops lirc_mode2_prog_ops = {
18};
19
20BPF_CALL_1(bpf_rc_repeat, u32*, sample)
21{
22	struct ir_raw_event_ctrl *ctrl;
23
24	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
25
26	rc_repeat(ctrl->dev);
27
28	return 0;
29}
30
31static const struct bpf_func_proto rc_repeat_proto = {
32	.func	   = bpf_rc_repeat,
33	.gpl_only  = true, /* rc_repeat is EXPORT_SYMBOL_GPL */
34	.ret_type  = RET_INTEGER,
35	.arg1_type = ARG_PTR_TO_CTX,
36};
37
38BPF_CALL_4(bpf_rc_keydown, u32*, sample, u32, protocol, u64, scancode,
39	   u32, toggle)
40{
41	struct ir_raw_event_ctrl *ctrl;
42
43	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
44
45	rc_keydown(ctrl->dev, protocol, scancode, toggle != 0);
46
47	return 0;
48}
49
50static const struct bpf_func_proto rc_keydown_proto = {
51	.func	   = bpf_rc_keydown,
52	.gpl_only  = true, /* rc_keydown is EXPORT_SYMBOL_GPL */
53	.ret_type  = RET_INTEGER,
54	.arg1_type = ARG_PTR_TO_CTX,
55	.arg2_type = ARG_ANYTHING,
56	.arg3_type = ARG_ANYTHING,
57	.arg4_type = ARG_ANYTHING,
58};
59
60BPF_CALL_3(bpf_rc_pointer_rel, u32*, sample, s32, rel_x, s32, rel_y)
61{
62	struct ir_raw_event_ctrl *ctrl;
63
64	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
65
66	input_report_rel(ctrl->dev->input_dev, REL_X, rel_x);
67	input_report_rel(ctrl->dev->input_dev, REL_Y, rel_y);
68	input_sync(ctrl->dev->input_dev);
69
70	return 0;
71}
72
73static const struct bpf_func_proto rc_pointer_rel_proto = {
74	.func	   = bpf_rc_pointer_rel,
75	.gpl_only  = true,
76	.ret_type  = RET_INTEGER,
77	.arg1_type = ARG_PTR_TO_CTX,
78	.arg2_type = ARG_ANYTHING,
79	.arg3_type = ARG_ANYTHING,
80};
81
82static const struct bpf_func_proto *
83lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
84{
85	switch (func_id) {
86	case BPF_FUNC_rc_repeat:
87		return &rc_repeat_proto;
88	case BPF_FUNC_rc_keydown:
89		return &rc_keydown_proto;
90	case BPF_FUNC_rc_pointer_rel:
91		return &rc_pointer_rel_proto;
92	case BPF_FUNC_map_lookup_elem:
93		return &bpf_map_lookup_elem_proto;
94	case BPF_FUNC_map_update_elem:
95		return &bpf_map_update_elem_proto;
96	case BPF_FUNC_map_delete_elem:
97		return &bpf_map_delete_elem_proto;
98	case BPF_FUNC_map_push_elem:
99		return &bpf_map_push_elem_proto;
100	case BPF_FUNC_map_pop_elem:
101		return &bpf_map_pop_elem_proto;
102	case BPF_FUNC_map_peek_elem:
103		return &bpf_map_peek_elem_proto;
104	case BPF_FUNC_ktime_get_ns:
105		return &bpf_ktime_get_ns_proto;
106	case BPF_FUNC_ktime_get_boot_ns:
107		return &bpf_ktime_get_boot_ns_proto;
108	case BPF_FUNC_tail_call:
109		return &bpf_tail_call_proto;
110	case BPF_FUNC_get_prandom_u32:
111		return &bpf_get_prandom_u32_proto;
112	case BPF_FUNC_trace_printk:
113		if (bpf_token_capable(prog->aux->token, CAP_PERFMON))
114			return bpf_get_trace_printk_proto();
115		fallthrough;
116	default:
117		return NULL;
118	}
119}
120
121static bool lirc_mode2_is_valid_access(int off, int size,
122				       enum bpf_access_type type,
123				       const struct bpf_prog *prog,
124				       struct bpf_insn_access_aux *info)
125{
126	/* We have one field of u32 */
127	return type == BPF_READ && off == 0 && size == sizeof(u32);
128}
129
130const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
131	.get_func_proto  = lirc_mode2_func_proto,
132	.is_valid_access = lirc_mode2_is_valid_access
133};
134
135#define BPF_MAX_PROGS 64
136
137static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
138{
139	struct bpf_prog_array *old_array;
140	struct bpf_prog_array *new_array;
141	struct ir_raw_event_ctrl *raw;
142	int ret;
143
144	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
145		return -EINVAL;
146
147	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
148	if (ret)
149		return ret;
150
151	raw = rcdev->raw;
152	if (!raw) {
153		ret = -ENODEV;
154		goto unlock;
155	}
156
157	old_array = lirc_rcu_dereference(raw->progs);
158	if (old_array && bpf_prog_array_length(old_array) >= BPF_MAX_PROGS) {
159		ret = -E2BIG;
160		goto unlock;
161	}
162
163	ret = bpf_prog_array_copy(old_array, NULL, prog, 0, &new_array);
164	if (ret < 0)
165		goto unlock;
166
167	rcu_assign_pointer(raw->progs, new_array);
168	bpf_prog_array_free(old_array);
169
170unlock:
171	mutex_unlock(&ir_raw_handler_lock);
172	return ret;
173}
174
175static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
176{
177	struct bpf_prog_array *old_array;
178	struct bpf_prog_array *new_array;
179	struct ir_raw_event_ctrl *raw;
180	int ret;
181
182	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
183		return -EINVAL;
184
185	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
186	if (ret)
187		return ret;
188
189	raw = rcdev->raw;
190	if (!raw) {
191		ret = -ENODEV;
192		goto unlock;
193	}
194
195	old_array = lirc_rcu_dereference(raw->progs);
196	ret = bpf_prog_array_copy(old_array, prog, NULL, 0, &new_array);
197	/*
198	 * Do not use bpf_prog_array_delete_safe() as we would end up
199	 * with a dummy entry in the array, and the we would free the
200	 * dummy in lirc_bpf_free()
201	 */
202	if (ret)
203		goto unlock;
204
205	rcu_assign_pointer(raw->progs, new_array);
206	bpf_prog_array_free(old_array);
207	bpf_prog_put(prog);
208unlock:
209	mutex_unlock(&ir_raw_handler_lock);
210	return ret;
211}
212
213void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
214{
215	struct ir_raw_event_ctrl *raw = rcdev->raw;
216
217	raw->bpf_sample = sample;
218
219	if (raw->progs) {
220		rcu_read_lock();
221		bpf_prog_run_array(rcu_dereference(raw->progs),
222				   &raw->bpf_sample, bpf_prog_run);
223		rcu_read_unlock();
224	}
225}
226
227/*
228 * This should be called once the rc thread has been stopped, so there can be
229 * no concurrent bpf execution.
230 *
231 * Should be called with the ir_raw_handler_lock held.
232 */
233void lirc_bpf_free(struct rc_dev *rcdev)
234{
235	struct bpf_prog_array_item *item;
236	struct bpf_prog_array *array;
237
238	array = lirc_rcu_dereference(rcdev->raw->progs);
239	if (!array)
240		return;
241
242	for (item = array->items; item->prog; item++)
243		bpf_prog_put(item->prog);
244
245	bpf_prog_array_free(array);
246}
247
248int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
249{
250	struct rc_dev *rcdev;
251	int ret;
252
253	if (attr->attach_flags)
254		return -EINVAL;
255
256	rcdev = rc_dev_get_from_fd(attr->target_fd, true);
257	if (IS_ERR(rcdev))
258		return PTR_ERR(rcdev);
259
260	ret = lirc_bpf_attach(rcdev, prog);
261
262	put_device(&rcdev->dev);
263
264	return ret;
265}
266
267int lirc_prog_detach(const union bpf_attr *attr)
268{
269	struct bpf_prog *prog;
270	struct rc_dev *rcdev;
271	int ret;
272
273	if (attr->attach_flags)
274		return -EINVAL;
275
276	prog = bpf_prog_get_type(attr->attach_bpf_fd,
277				 BPF_PROG_TYPE_LIRC_MODE2);
278	if (IS_ERR(prog))
279		return PTR_ERR(prog);
280
281	rcdev = rc_dev_get_from_fd(attr->target_fd, true);
282	if (IS_ERR(rcdev)) {
283		bpf_prog_put(prog);
284		return PTR_ERR(rcdev);
285	}
286
287	ret = lirc_bpf_detach(rcdev, prog);
288
289	bpf_prog_put(prog);
290	put_device(&rcdev->dev);
291
292	return ret;
293}
294
295int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
296{
297	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
298	struct bpf_prog_array *progs;
299	struct rc_dev *rcdev;
300	u32 cnt, flags = 0;
301	int ret;
302
303	if (attr->query.query_flags)
304		return -EINVAL;
305
306	rcdev = rc_dev_get_from_fd(attr->query.target_fd, false);
307	if (IS_ERR(rcdev))
308		return PTR_ERR(rcdev);
309
310	if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
311		ret = -EINVAL;
312		goto put;
313	}
314
315	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
316	if (ret)
317		goto put;
318
319	progs = lirc_rcu_dereference(rcdev->raw->progs);
320	cnt = progs ? bpf_prog_array_length(progs) : 0;
321
322	if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
323		ret = -EFAULT;
324		goto unlock;
325	}
326
327	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
328		ret = -EFAULT;
329		goto unlock;
330	}
331
332	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
333		ret = bpf_prog_array_copy_to_user(progs, prog_ids,
334						  attr->query.prog_cnt);
335
336unlock:
337	mutex_unlock(&ir_raw_handler_lock);
338put:
339	put_device(&rcdev->dev);
340
341	return ret;
342}
343