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 */
17 const struct bpf_prog_ops lirc_mode2_prog_ops = {
18 };
19
BPF_CALL_1(bpf_rc_repeat,u32 *,sample)20 BPF_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
31 static 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
BPF_CALL_4(bpf_rc_keydown,u32 *,sample,u32,protocol,u64,scancode,u32,toggle)38 BPF_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
50 static 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
BPF_CALL_3(bpf_rc_pointer_rel,u32 *,sample,s32,rel_x,s32,rel_y)60 BPF_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
73 static 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
82 static const struct bpf_func_proto *
lirc_mode2_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)83 lirc_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 (perfmon_capable())
114 return bpf_get_trace_printk_proto();
115 fallthrough;
116 default:
117 return NULL;
118 }
119 }
120
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)121 static 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
130 const 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
lirc_bpf_attach(struct rc_dev * rcdev,struct bpf_prog * prog)137 static 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, &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
170 unlock:
171 mutex_unlock(&ir_raw_handler_lock);
172 return ret;
173 }
174
lirc_bpf_detach(struct rc_dev * rcdev,struct bpf_prog * prog)175 static 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, &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);
208 unlock:
209 mutex_unlock(&ir_raw_handler_lock);
210 return ret;
211 }
212
lirc_bpf_run(struct rc_dev * rcdev,u32 sample)213 void 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 BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN);
221 }
222
223 /*
224 * This should be called once the rc thread has been stopped, so there can be
225 * no concurrent bpf execution.
226 *
227 * Should be called with the ir_raw_handler_lock held.
228 */
lirc_bpf_free(struct rc_dev * rcdev)229 void lirc_bpf_free(struct rc_dev *rcdev)
230 {
231 struct bpf_prog_array_item *item;
232 struct bpf_prog_array *array;
233
234 array = lirc_rcu_dereference(rcdev->raw->progs);
235 if (!array)
236 return;
237
238 for (item = array->items; item->prog; item++)
239 bpf_prog_put(item->prog);
240
241 bpf_prog_array_free(array);
242 }
243
lirc_prog_attach(const union bpf_attr * attr,struct bpf_prog * prog)244 int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
245 {
246 struct rc_dev *rcdev;
247 int ret;
248
249 if (attr->attach_flags)
250 return -EINVAL;
251
252 rcdev = rc_dev_get_from_fd(attr->target_fd);
253 if (IS_ERR(rcdev))
254 return PTR_ERR(rcdev);
255
256 ret = lirc_bpf_attach(rcdev, prog);
257
258 put_device(&rcdev->dev);
259
260 return ret;
261 }
262
lirc_prog_detach(const union bpf_attr * attr)263 int lirc_prog_detach(const union bpf_attr *attr)
264 {
265 struct bpf_prog *prog;
266 struct rc_dev *rcdev;
267 int ret;
268
269 if (attr->attach_flags)
270 return -EINVAL;
271
272 prog = bpf_prog_get_type(attr->attach_bpf_fd,
273 BPF_PROG_TYPE_LIRC_MODE2);
274 if (IS_ERR(prog))
275 return PTR_ERR(prog);
276
277 rcdev = rc_dev_get_from_fd(attr->target_fd);
278 if (IS_ERR(rcdev)) {
279 bpf_prog_put(prog);
280 return PTR_ERR(rcdev);
281 }
282
283 ret = lirc_bpf_detach(rcdev, prog);
284
285 bpf_prog_put(prog);
286 put_device(&rcdev->dev);
287
288 return ret;
289 }
290
lirc_prog_query(const union bpf_attr * attr,union bpf_attr __user * uattr)291 int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
292 {
293 __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
294 struct bpf_prog_array *progs;
295 struct rc_dev *rcdev;
296 u32 cnt, flags = 0;
297 int ret;
298
299 if (attr->query.query_flags)
300 return -EINVAL;
301
302 rcdev = rc_dev_get_from_fd(attr->query.target_fd);
303 if (IS_ERR(rcdev))
304 return PTR_ERR(rcdev);
305
306 if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
307 ret = -EINVAL;
308 goto put;
309 }
310
311 ret = mutex_lock_interruptible(&ir_raw_handler_lock);
312 if (ret)
313 goto put;
314
315 progs = lirc_rcu_dereference(rcdev->raw->progs);
316 cnt = progs ? bpf_prog_array_length(progs) : 0;
317
318 if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
319 ret = -EFAULT;
320 goto unlock;
321 }
322
323 if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
324 ret = -EFAULT;
325 goto unlock;
326 }
327
328 if (attr->query.prog_cnt != 0 && prog_ids && cnt)
329 ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
330
331 unlock:
332 mutex_unlock(&ir_raw_handler_lock);
333 put:
334 put_device(&rcdev->dev);
335
336 return ret;
337 }
338