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_tail_call:
 107                 return &bpf_tail_call_proto;
 108         case BPF_FUNC_get_prandom_u32:
 109                 return &bpf_get_prandom_u32_proto;
 110         case BPF_FUNC_trace_printk:
 111                 if (capable(CAP_SYS_ADMIN))
 112                         return bpf_get_trace_printk_proto();
 113                 /* fall through */
 114         default:
 115                 return NULL;
 116         }
 117 }
 118
 119 static bool lirc_mode2_is_valid_access(int off, int size,
 120                                        enum bpf_access_type type,
 121                                        const struct bpf_prog *prog,
 122                                        struct bpf_insn_access_aux *info)
 123 {
 124         /* We have one field of u32 */
 125         return type == BPF_READ && off == 0 && size == sizeof(u32);
 126 }
 127
 128 const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
 129         .get_func_proto  = lirc_mode2_func_proto,
 130         .is_valid_access = lirc_mode2_is_valid_access
 131 };
 132
 133 #define BPF_MAX_PROGS 64
 134
 135 static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
 136 {
 137         struct bpf_prog_array *old_array;
 138         struct bpf_prog_array *new_array;
 139         struct ir_raw_event_ctrl *raw;
 140         int ret;
 141
 142         if (rcdev->driver_type != RC_DRIVER_IR_RAW)
 143                 return -EINVAL;
 144
 145         ret = mutex_lock_interruptible(&ir_raw_handler_lock);
 146         if (ret)
 147                 return ret;
 148
 149         raw = rcdev->raw;
 150         if (!raw) {
 151                 ret = -ENODEV;
 152                 goto unlock;
 153         }
 154
 155         old_array = lirc_rcu_dereference(raw->progs);
 156         if (old_array && bpf_prog_array_length(old_array) >= BPF_MAX_PROGS) {
 157                 ret = -E2BIG;
 158                 goto unlock;
 159         }
 160
 161         ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
 162         if (ret < 0)
 163                 goto unlock;
 164
 165         rcu_assign_pointer(raw->progs, new_array);
 166         bpf_prog_array_free(old_array);
 167
 168 unlock:
 169         mutex_unlock(&ir_raw_handler_lock);
 170         return ret;
 171 }
 172
 173 static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
 174 {
 175         struct bpf_prog_array *old_array;
 176         struct bpf_prog_array *new_array;
 177         struct ir_raw_event_ctrl *raw;
 178         int ret;
 179
 180         if (rcdev->driver_type != RC_DRIVER_IR_RAW)
 181                 return -EINVAL;
 182
 183         ret = mutex_lock_interruptible(&ir_raw_handler_lock);
 184         if (ret)
 185                 return ret;
 186
 187         raw = rcdev->raw;
 188         if (!raw) {
 189                 ret = -ENODEV;
 190                 goto unlock;
 191         }
 192
 193         old_array = lirc_rcu_dereference(raw->progs);
 194         ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
 195         /*
 196          * Do not use bpf_prog_array_delete_safe() as we would end up
 197          * with a dummy entry in the array, and the we would free the
 198          * dummy in lirc_bpf_free()
 199          */
 200         if (ret)
 201                 goto unlock;
 202
 203         rcu_assign_pointer(raw->progs, new_array);
 204         bpf_prog_array_free(old_array);
 205         bpf_prog_put(prog);
 206 unlock:
 207         mutex_unlock(&ir_raw_handler_lock);
 208         return ret;
 209 }
 210
 211 void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
 212 {
 213         struct ir_raw_event_ctrl *raw = rcdev->raw;
 214
 215         raw->bpf_sample = sample;
 216
 217         if (raw->progs)
 218                 BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN);
 219 }
 220
 221 /*
 222  * This should be called once the rc thread has been stopped, so there can be
 223  * no concurrent bpf execution.
 224  *
 225  * Should be called with the ir_raw_handler_lock held.
 226  */
 227 void lirc_bpf_free(struct rc_dev *rcdev)
 228 {
 229         struct bpf_prog_array_item *item;
 230         struct bpf_prog_array *array;
 231
 232         array = lirc_rcu_dereference(rcdev->raw->progs);
 233         if (!array)
 234                 return;
 235
 236         for (item = array->items; item->prog; item++)
 237                 bpf_prog_put(item->prog);
 238
 239         bpf_prog_array_free(array);
 240 }
 241
 242 int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 243 {
 244         struct rc_dev *rcdev;
 245         int ret;
 246
 247         if (attr->attach_flags)
 248                 return -EINVAL;
 249
 250         rcdev = rc_dev_get_from_fd(attr->target_fd);
 251         if (IS_ERR(rcdev))
 252                 return PTR_ERR(rcdev);
 253
 254         ret = lirc_bpf_attach(rcdev, prog);
 255
 256         put_device(&rcdev->dev);
 257
 258         return ret;
 259 }
 260
 261 int lirc_prog_detach(const union bpf_attr *attr)
 262 {
 263         struct bpf_prog *prog;
 264         struct rc_dev *rcdev;
 265         int ret;
 266
 267         if (attr->attach_flags)
 268                 return -EINVAL;
 269
 270         prog = bpf_prog_get_type(attr->attach_bpf_fd,
 271                                  BPF_PROG_TYPE_LIRC_MODE2);
 272         if (IS_ERR(prog))
 273                 return PTR_ERR(prog);
 274
 275         rcdev = rc_dev_get_from_fd(attr->target_fd);
 276         if (IS_ERR(rcdev)) {
 277                 bpf_prog_put(prog);
 278                 return PTR_ERR(rcdev);
 279         }
 280
 281         ret = lirc_bpf_detach(rcdev, prog);
 282
 283         bpf_prog_put(prog);
 284         put_device(&rcdev->dev);
 285
 286         return ret;
 287 }
 288
 289 int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
 290 {
 291         __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
 292         struct bpf_prog_array *progs;
 293         struct rc_dev *rcdev;
 294         u32 cnt, flags = 0;
 295         int ret;
 296
 297         if (attr->query.query_flags)
 298                 return -EINVAL;
 299
 300         rcdev = rc_dev_get_from_fd(attr->query.target_fd);
 301         if (IS_ERR(rcdev))
 302                 return PTR_ERR(rcdev);
 303
 304         if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
 305                 ret = -EINVAL;
 306                 goto put;
 307         }
 308
 309         ret = mutex_lock_interruptible(&ir_raw_handler_lock);
 310         if (ret)
 311                 goto put;
 312
 313         progs = lirc_rcu_dereference(rcdev->raw->progs);
 314         cnt = progs ? bpf_prog_array_length(progs) : 0;
 315
 316         if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
 317                 ret = -EFAULT;
 318                 goto unlock;
 319         }
 320
 321         if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
 322                 ret = -EFAULT;
 323                 goto unlock;
 324         }
 325
 326         if (attr->query.prog_cnt != 0 && prog_ids && cnt)
 327                 ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
 328
 329 unlock:
 330         mutex_unlock(&ir_raw_handler_lock);
 331 put:
 332         put_device(&rcdev->dev);
 333
 334         return ret;
 335 }