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 /*
  12  * BPF interface for raw IR
  13  */
  14 const struct bpf_prog_ops lirc_mode2_prog_ops = {
  15 };
  16
  17 BPF_CALL_1(bpf_rc_repeat, u32*, sample)
  18 {
  19         struct ir_raw_event_ctrl *ctrl;
  20
  21         ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
  22
  23         rc_repeat(ctrl->dev);
  24
  25         return 0;
  26 }
  27
  28 static const struct bpf_func_proto rc_repeat_proto = {
  29         .func      = bpf_rc_repeat,
  30         .gpl_only  = true, /* rc_repeat is EXPORT_SYMBOL_GPL */
  31         .ret_type  = RET_INTEGER,
  32         .arg1_type = ARG_PTR_TO_CTX,
  33 };
  34
  35 /*
  36  * Currently rc-core does not support 64-bit scancodes, but there are many
  37  * known protocols with more than 32 bits. So, define the interface as u64
  38  * as a future-proof.
  39  */
  40 BPF_CALL_4(bpf_rc_keydown, u32*, sample, u32, protocol, u64, scancode,
  41            u32, toggle)
  42 {
  43         struct ir_raw_event_ctrl *ctrl;
  44
  45         ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
  46
  47         rc_keydown(ctrl->dev, protocol, scancode, toggle != 0);
  48
  49         return 0;
  50 }
  51
  52 static const struct bpf_func_proto rc_keydown_proto = {
  53         .func      = bpf_rc_keydown,
  54         .gpl_only  = true, /* rc_keydown is EXPORT_SYMBOL_GPL */
  55         .ret_type  = RET_INTEGER,
  56         .arg1_type = ARG_PTR_TO_CTX,
  57         .arg2_type = ARG_ANYTHING,
  58         .arg3_type = ARG_ANYTHING,
  59         .arg4_type = ARG_ANYTHING,
  60 };
  61
  62 BPF_CALL_3(bpf_rc_pointer_rel, u32*, sample, s32, rel_x, s32, rel_y)
  63 {
  64         struct ir_raw_event_ctrl *ctrl;
  65
  66         ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
  67
  68         input_report_rel(ctrl->dev->input_dev, REL_X, rel_x);
  69         input_report_rel(ctrl->dev->input_dev, REL_Y, rel_y);
  70         input_sync(ctrl->dev->input_dev);
  71
  72         return 0;
  73 }
  74
  75 static const struct bpf_func_proto rc_pointer_rel_proto = {
  76         .func      = bpf_rc_pointer_rel,
  77         .gpl_only  = true,
  78         .ret_type  = RET_INTEGER,
  79         .arg1_type = ARG_PTR_TO_CTX,
  80         .arg2_type = ARG_ANYTHING,
  81         .arg3_type = ARG_ANYTHING,
  82 };
  83
  84 static const struct bpf_func_proto *
  85 lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
  86 {
  87         switch (func_id) {
  88         case BPF_FUNC_rc_repeat:
  89                 return &rc_repeat_proto;
  90         case BPF_FUNC_rc_keydown:
  91                 return &rc_keydown_proto;
  92         case BPF_FUNC_rc_pointer_rel:
  93                 return &rc_pointer_rel_proto;
  94         case BPF_FUNC_map_lookup_elem:
  95                 return &bpf_map_lookup_elem_proto;
  96         case BPF_FUNC_map_update_elem:
  97                 return &bpf_map_update_elem_proto;
  98         case BPF_FUNC_map_delete_elem:
  99                 return &bpf_map_delete_elem_proto;
 100         case BPF_FUNC_map_push_elem:
 101                 return &bpf_map_push_elem_proto;
 102         case BPF_FUNC_map_pop_elem:
 103                 return &bpf_map_pop_elem_proto;
 104         case BPF_FUNC_map_peek_elem:
 105                 return &bpf_map_peek_elem_proto;
 106         case BPF_FUNC_ktime_get_ns:
 107                 return &bpf_ktime_get_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 (capable(CAP_SYS_ADMIN))
 114                         return bpf_get_trace_printk_proto();
 115                 /* fall through */
 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 __rcu *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         if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
 158                 ret = -E2BIG;
 159                 goto unlock;
 160         }
 161
 162         old_array = raw->progs;
 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
 175 static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
 176 {
 177         struct bpf_prog_array __rcu *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 = 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
 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 void lirc_bpf_free(struct rc_dev *rcdev)
 228 {
 229         struct bpf_prog_array_item *item;
 230
 231         if (!rcdev->raw->progs)
 232                 return;
 233
 234         item = rcu_dereference(rcdev->raw->progs)->items;
 235         while (item->prog) {
 236                 bpf_prog_put(item->prog);
 237                 item++;
 238         }
 239
 240         bpf_prog_array_free(rcdev->raw->progs);
 241 }
 242
 243 int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 244 {
 245         struct rc_dev *rcdev;
 246         int ret;
 247
 248         if (attr->attach_flags)
 249                 return -EINVAL;
 250
 251         rcdev = rc_dev_get_from_fd(attr->target_fd);
 252         if (IS_ERR(rcdev))
 253                 return PTR_ERR(rcdev);
 254
 255         ret = lirc_bpf_attach(rcdev, prog);
 256
 257         put_device(&rcdev->dev);
 258
 259         return ret;
 260 }
 261
 262 int lirc_prog_detach(const union bpf_attr *attr)
 263 {
 264         struct bpf_prog *prog;
 265         struct rc_dev *rcdev;
 266         int ret;
 267
 268         if (attr->attach_flags)
 269                 return -EINVAL;
 270
 271         prog = bpf_prog_get_type(attr->attach_bpf_fd,
 272                                  BPF_PROG_TYPE_LIRC_MODE2);
 273         if (IS_ERR(prog))
 274                 return PTR_ERR(prog);
 275
 276         rcdev = rc_dev_get_from_fd(attr->target_fd);
 277         if (IS_ERR(rcdev)) {
 278                 bpf_prog_put(prog);
 279                 return PTR_ERR(rcdev);
 280         }
 281
 282         ret = lirc_bpf_detach(rcdev, prog);
 283
 284         bpf_prog_put(prog);
 285         put_device(&rcdev->dev);
 286
 287         return ret;
 288 }
 289
 290 int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
 291 {
 292         __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
 293         struct bpf_prog_array __rcu *progs;
 294         struct rc_dev *rcdev;
 295         u32 cnt, flags = 0;
 296         int ret;
 297
 298         if (attr->query.query_flags)
 299                 return -EINVAL;
 300
 301         rcdev = rc_dev_get_from_fd(attr->query.target_fd);
 302         if (IS_ERR(rcdev))
 303                 return PTR_ERR(rcdev);
 304
 305         if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
 306                 ret = -EINVAL;
 307                 goto put;
 308         }
 309
 310         ret = mutex_lock_interruptible(&ir_raw_handler_lock);
 311         if (ret)
 312                 goto put;
 313
 314         progs = rcdev->raw->progs;
 315         cnt = progs ? bpf_prog_array_length(progs) : 0;
 316
 317         if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
 318                 ret = -EFAULT;
 319                 goto unlock;
 320         }
 321
 322         if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
 323                 ret = -EFAULT;
 324                 goto unlock;
 325         }
 326
 327         if (attr->query.prog_cnt != 0 && prog_ids && cnt)
 328                 ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
 329
 330 unlock:
 331         mutex_unlock(&ir_raw_handler_lock);
 332 put:
 333         put_device(&rcdev->dev);
 334
 335         return ret;
 336 }