drivers/media/rc/bpf-lirc.c

   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
  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
  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
  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 *
  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 (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
 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
 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, 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
 170 unlock:
 171         mutex_unlock(&ir_raw_handler_lock);
 172         return ret;
 173 }
 174
 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, 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);
 208 unlock:
 209         mutex_unlock(&ir_raw_handler_lock);
 210         return ret;
 211 }
 212
 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                 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  */
 233 void 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
 248 int 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
 267 int 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
 295 int 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
 336 unlock:
 337         mutex_unlock(&ir_raw_handler_lock);
 338 put:
 339         put_device(&rcdev->dev);
 340
 341         return ret;
 342 }