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 static const struct bpf_func_proto * 63 lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 64 { 65 switch (func_id) { 66 case BPF_FUNC_rc_repeat: 67 return &rc_repeat_proto; 68 case BPF_FUNC_rc_keydown: 69 return &rc_keydown_proto; 70 case BPF_FUNC_map_lookup_elem: 71 return &bpf_map_lookup_elem_proto; 72 case BPF_FUNC_map_update_elem: 73 return &bpf_map_update_elem_proto; 74 case BPF_FUNC_map_delete_elem: 75 return &bpf_map_delete_elem_proto; 76 case BPF_FUNC_ktime_get_ns: 77 return &bpf_ktime_get_ns_proto; 78 case BPF_FUNC_tail_call: 79 return &bpf_tail_call_proto; 80 case BPF_FUNC_get_prandom_u32: 81 return &bpf_get_prandom_u32_proto; 82 case BPF_FUNC_trace_printk: 83 if (capable(CAP_SYS_ADMIN)) 84 return bpf_get_trace_printk_proto(); 85 /* fall through */ 86 default: 87 return NULL; 88 } 89 } 90 91 static bool lirc_mode2_is_valid_access(int off, int size, 92 enum bpf_access_type type, 93 const struct bpf_prog *prog, 94 struct bpf_insn_access_aux *info) 95 { 96 /* We have one field of u32 */ 97 return type == BPF_READ && off == 0 && size == sizeof(u32); 98 } 99 100 const struct bpf_verifier_ops lirc_mode2_verifier_ops = { 101 .get_func_proto = lirc_mode2_func_proto, 102 .is_valid_access = lirc_mode2_is_valid_access 103 }; 104 105 #define BPF_MAX_PROGS 64 106 107 static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog) 108 { 109 struct bpf_prog_array __rcu *old_array; 110 struct bpf_prog_array *new_array; 111 struct ir_raw_event_ctrl *raw; 112 int ret; 113 114 if (rcdev->driver_type != RC_DRIVER_IR_RAW) 115 return -EINVAL; 116 117 ret = mutex_lock_interruptible(&ir_raw_handler_lock); 118 if (ret) 119 return ret; 120 121 raw = rcdev->raw; 122 if (!raw) { 123 ret = -ENODEV; 124 goto unlock; 125 } 126 127 if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) { 128 ret = -E2BIG; 129 goto unlock; 130 } 131 132 old_array = raw->progs; 133 ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array); 134 if (ret < 0) 135 goto unlock; 136 137 rcu_assign_pointer(raw->progs, new_array); 138 bpf_prog_array_free(old_array); 139 140 unlock: 141 mutex_unlock(&ir_raw_handler_lock); 142 return ret; 143 } 144 145 static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog) 146 { 147 struct bpf_prog_array __rcu *old_array; 148 struct bpf_prog_array *new_array; 149 struct ir_raw_event_ctrl *raw; 150 int ret; 151 152 if (rcdev->driver_type != RC_DRIVER_IR_RAW) 153 return -EINVAL; 154 155 ret = mutex_lock_interruptible(&ir_raw_handler_lock); 156 if (ret) 157 return ret; 158 159 raw = rcdev->raw; 160 if (!raw) { 161 ret = -ENODEV; 162 goto unlock; 163 } 164 165 old_array = raw->progs; 166 ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array); 167 /* 168 * Do not use bpf_prog_array_delete_safe() as we would end up 169 * with a dummy entry in the array, and the we would free the 170 * dummy in lirc_bpf_free() 171 */ 172 if (ret) 173 goto unlock; 174 175 rcu_assign_pointer(raw->progs, new_array); 176 bpf_prog_array_free(old_array); 177 unlock: 178 mutex_unlock(&ir_raw_handler_lock); 179 return ret; 180 } 181 182 void lirc_bpf_run(struct rc_dev *rcdev, u32 sample) 183 { 184 struct ir_raw_event_ctrl *raw = rcdev->raw; 185 186 raw->bpf_sample = sample; 187 188 if (raw->progs) 189 BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN); 190 } 191 192 /* 193 * This should be called once the rc thread has been stopped, so there can be 194 * no concurrent bpf execution. 195 */ 196 void lirc_bpf_free(struct rc_dev *rcdev) 197 { 198 struct bpf_prog **progs; 199 200 if (!rcdev->raw->progs) 201 return; 202 203 progs = rcu_dereference(rcdev->raw->progs)->progs; 204 while (*progs) 205 bpf_prog_put(*progs++); 206 207 bpf_prog_array_free(rcdev->raw->progs); 208 } 209 210 int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog) 211 { 212 struct rc_dev *rcdev; 213 int ret; 214 215 if (attr->attach_flags) 216 return -EINVAL; 217 218 rcdev = rc_dev_get_from_fd(attr->target_fd); 219 if (IS_ERR(rcdev)) 220 return PTR_ERR(rcdev); 221 222 ret = lirc_bpf_attach(rcdev, prog); 223 224 put_device(&rcdev->dev); 225 226 return ret; 227 } 228 229 int lirc_prog_detach(const union bpf_attr *attr) 230 { 231 struct bpf_prog *prog; 232 struct rc_dev *rcdev; 233 int ret; 234 235 if (attr->attach_flags) 236 return -EINVAL; 237 238 prog = bpf_prog_get_type(attr->attach_bpf_fd, 239 BPF_PROG_TYPE_LIRC_MODE2); 240 if (IS_ERR(prog)) 241 return PTR_ERR(prog); 242 243 rcdev = rc_dev_get_from_fd(attr->target_fd); 244 if (IS_ERR(rcdev)) { 245 bpf_prog_put(prog); 246 return PTR_ERR(rcdev); 247 } 248 249 ret = lirc_bpf_detach(rcdev, prog); 250 251 bpf_prog_put(prog); 252 put_device(&rcdev->dev); 253 254 return ret; 255 } 256 257 int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) 258 { 259 __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); 260 struct bpf_prog_array __rcu *progs; 261 struct rc_dev *rcdev; 262 u32 cnt, flags = 0; 263 int ret; 264 265 if (attr->query.query_flags) 266 return -EINVAL; 267 268 rcdev = rc_dev_get_from_fd(attr->query.target_fd); 269 if (IS_ERR(rcdev)) 270 return PTR_ERR(rcdev); 271 272 if (rcdev->driver_type != RC_DRIVER_IR_RAW) { 273 ret = -EINVAL; 274 goto put; 275 } 276 277 ret = mutex_lock_interruptible(&ir_raw_handler_lock); 278 if (ret) 279 goto put; 280 281 progs = rcdev->raw->progs; 282 cnt = progs ? bpf_prog_array_length(progs) : 0; 283 284 if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) { 285 ret = -EFAULT; 286 goto unlock; 287 } 288 289 if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) { 290 ret = -EFAULT; 291 goto unlock; 292 } 293 294 if (attr->query.prog_cnt != 0 && prog_ids && cnt) 295 ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt); 296 297 unlock: 298 mutex_unlock(&ir_raw_handler_lock); 299 put: 300 put_device(&rcdev->dev); 301 302 return ret; 303 } 304