src/shared/udev-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <sys/inotify.h>
   6 #include <unistd.h>
   7
   8 #include "alloc-util.h"
   9 #include "device-nodes.h"
  10 #include "device-util.h"
  11 #include "env-file.h"
  12 #include "escape.h"
  13 #include "fd-util.h"
  14 #include "log.h"
  15 #include "macro.h"
  16 #include "parse-util.h"
  17 #include "path-util.h"
  18 #include "signal-util.h"
  19 #include "string-table.h"
  20 #include "string-util.h"
  21 #include "strxcpyx.h"
  22 #include "udev-util.h"
  23 #include "utf8.h"
  24
  25 static const char* const resolve_name_timing_table[_RESOLVE_NAME_TIMING_MAX] = {
  26         [RESOLVE_NAME_NEVER] = "never",
  27         [RESOLVE_NAME_LATE] = "late",
  28         [RESOLVE_NAME_EARLY] = "early",
  29 };
  30
  31 DEFINE_STRING_TABLE_LOOKUP(resolve_name_timing, ResolveNameTiming);
  32
  33 int udev_parse_config_full(
  34                 unsigned *ret_children_max,
  35                 usec_t *ret_exec_delay_usec,
  36                 usec_t *ret_event_timeout_usec,
  37                 ResolveNameTiming *ret_resolve_name_timing,
  38                 int *ret_timeout_signal) {
  39
  40         _cleanup_free_ char *log_val = NULL, *children_max = NULL, *exec_delay = NULL, *event_timeout = NULL, *resolve_names = NULL, *timeout_signal = NULL;
  41         int r;
  42
  43         r = parse_env_file(NULL, "/etc/udev/udev.conf",
  44                            "udev_log", &log_val,
  45                            "children_max", &children_max,
  46                            "exec_delay", &exec_delay,
  47                            "event_timeout", &event_timeout,
  48                            "resolve_names", &resolve_names,
  49                            "timeout_signal", &timeout_signal);
  50         if (r == -ENOENT)
  51                 return 0;
  52         if (r < 0)
  53                 return r;
  54
  55         if (log_val) {
  56                 const char *log;
  57                 size_t n;
  58
  59                 /* unquote */
  60                 n = strlen(log_val);
  61                 if (n >= 2 &&
  62                     ((log_val[0] == '"' && log_val[n-1] == '"') ||
  63                      (log_val[0] == '\'' && log_val[n-1] == '\''))) {
  64                         log_val[n - 1] = '\0';
  65                         log = log_val + 1;
  66                 } else
  67                         log = log_val;
  68
  69                 /* we set the udev log level here explicitly, this is supposed
  70                  * to regulate the code in libudev/ and udev/. */
  71                 r = log_set_max_level_from_string(log);
  72                 if (r < 0)
  73                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  74                                    "failed to set udev log level '%s', ignoring: %m", log);
  75         }
  76
  77         if (ret_children_max && children_max) {
  78                 r = safe_atou(children_max, ret_children_max);
  79                 if (r < 0)
  80                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  81                                    "failed to parse children_max=%s, ignoring: %m", children_max);
  82         }
  83
  84         if (ret_exec_delay_usec && exec_delay) {
  85                 r = parse_sec(exec_delay, ret_exec_delay_usec);
  86                 if (r < 0)
  87                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  88                                    "failed to parse exec_delay=%s, ignoring: %m", exec_delay);
  89         }
  90
  91         if (ret_event_timeout_usec && event_timeout) {
  92                 r = parse_sec(event_timeout, ret_event_timeout_usec);
  93                 if (r < 0)
  94                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  95                                    "failed to parse event_timeout=%s, ignoring: %m", event_timeout);
  96         }
  97
  98         if (ret_resolve_name_timing && resolve_names) {
  99                 ResolveNameTiming t;
 100
 101                 t = resolve_name_timing_from_string(resolve_names);
 102                 if (t < 0)
 103                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
 104                                    "failed to parse resolve_names=%s, ignoring.", resolve_names);
 105                 else
 106                         *ret_resolve_name_timing = t;
 107         }
 108
 109         if (ret_timeout_signal && timeout_signal) {
 110                 r = signal_from_string(timeout_signal);
 111                 if (r < 0)
 112                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
 113                                    "failed to parse timeout_signal=%s, ignoring: %m", timeout_signal);
 114                 else
 115                         *ret_timeout_signal = r;
 116         }
 117
 118         return 0;
 119 }
 120
 121 /* Note that if -ENOENT is returned, it will be logged at debug level rather than error,
 122  * because it's an expected, common occurrence that the caller will handle with a fallback */
 123 static int device_new_from_dev_path(const char *devlink, sd_device **ret_device) {
 124         struct stat st;
 125         int r;
 126
 127         assert(devlink);
 128
 129         if (stat(devlink, &st) < 0)
 130                 return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno,
 131                                       "Failed to stat() %s: %m", devlink);
 132
 133         if (!S_ISBLK(st.st_mode))
 134                 return log_error_errno(SYNTHETIC_ERRNO(ENOTBLK),
 135                                        "%s does not point to a block device: %m", devlink);
 136
 137         r = sd_device_new_from_devnum(ret_device, 'b', st.st_rdev);
 138         if (r < 0)
 139                 return log_error_errno(r, "Failed to initialize device from %s: %m", devlink);
 140
 141         return 0;
 142 }
 143
 144 struct DeviceMonitorData {
 145         const char *sysname;
 146         const char *devlink;
 147         sd_device *device;
 148 };
 149
 150 static void device_monitor_data_free(struct DeviceMonitorData *d) {
 151         assert(d);
 152
 153         sd_device_unref(d->device);
 154 }
 155
 156 static int device_monitor_handler(sd_device_monitor *monitor, sd_device *device, void *userdata) {
 157         struct DeviceMonitorData *data = userdata;
 158         const char *sysname;
 159
 160         assert(device);
 161         assert(data);
 162         assert(data->sysname || data->devlink);
 163         assert(!data->device);
 164
 165         /* Ignore REMOVE events here. We are waiting for initialization after all, not de-initialization. We
 166          * might see a REMOVE event from an earlier use of the device (devices by the same name are recycled
 167          * by the kernel after all), which we should not get confused by. After all we cannot distinguish use
 168          * cycles of the devices, as the udev queue is entirely asynchronous.
 169          *
 170          * If we see a REMOVE event here for the use cycle we actually care about then we won't notice of
 171          * course, but that should be OK, given the timeout logic used on the wait loop: this will be noticed
 172          * by means of -ETIMEDOUT. Thus we won't notice immediately, but eventually, and that should be
 173          * sufficient for an error path that should regularly not happen.
 174          *
 175          * (And yes, we only need to special case REMOVE. It's the only "negative" event type, where a device
 176          * ceases to exist. All other event types are "positive": the device exists and is registered in the
 177          * udev database, thus whenever we see the event, we can consider it initialized.) */
 178         if (device_for_action(device, DEVICE_ACTION_REMOVE))
 179                 return 0;
 180
 181         if (data->sysname && sd_device_get_sysname(device, &sysname) >= 0 && streq(sysname, data->sysname))
 182                 goto found;
 183
 184         if (data->devlink) {
 185                 const char *devlink;
 186
 187                 FOREACH_DEVICE_DEVLINK(device, devlink)
 188                         if (path_equal(devlink, data->devlink))
 189                                 goto found;
 190
 191                 if (sd_device_get_devname(device, &devlink) >= 0 && path_equal(devlink, data->devlink))
 192                         goto found;
 193         }
 194
 195         return 0;
 196
 197 found:
 198         data->device = sd_device_ref(device);
 199         return sd_event_exit(sd_device_monitor_get_event(monitor), 0);
 200 }
 201
 202 static int device_wait_for_initialization_internal(
 203                 sd_device *_device,
 204                 const char *devlink,
 205                 const char *subsystem,
 206                 usec_t deadline,
 207                 sd_device **ret) {
 208
 209         _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *monitor = NULL;
 210         _cleanup_(sd_event_source_unrefp) sd_event_source *timeout_source = NULL;
 211         _cleanup_(sd_event_unrefp) sd_event *event = NULL;
 212         /* Ensure that if !_device && devlink, device gets unrefd on errors since it will be new */
 213         _cleanup_(sd_device_unrefp) sd_device *device = sd_device_ref(_device);
 214         _cleanup_(device_monitor_data_free) struct DeviceMonitorData data = {
 215                 .devlink = devlink,
 216         };
 217         int r;
 218
 219         assert(device || (subsystem && devlink));
 220
 221         /* Devlink might already exist, if it does get the device to use the sysname filtering */
 222         if (!device && devlink) {
 223                 r = device_new_from_dev_path(devlink, &device);
 224                 if (r < 0 && r != -ENOENT)
 225                         return r;
 226         }
 227
 228         if (device) {
 229                 if (sd_device_get_is_initialized(device) > 0) {
 230                         if (ret)
 231                                 *ret = sd_device_ref(device);
 232                         return 0;
 233                 }
 234                 /* We need either the sysname or the devlink for filtering */
 235                 assert_se(sd_device_get_sysname(device, &data.sysname) >= 0 || devlink);
 236         }
 237
 238         /* Wait until the device is initialized, so that we can get access to the ID_PATH property */
 239
 240         r = sd_event_new(&event);
 241         if (r < 0)
 242                 return log_error_errno(r, "Failed to get default event: %m");
 243
 244         r = sd_device_monitor_new(&monitor);
 245         if (r < 0)
 246                 return log_error_errno(r, "Failed to acquire monitor: %m");
 247
 248         if (device && !subsystem) {
 249                 r = sd_device_get_subsystem(device, &subsystem);
 250                 if (r < 0 && r != -ENOENT)
 251                         return log_device_error_errno(device, r, "Failed to get subsystem: %m");
 252         }
 253
 254         if (subsystem) {
 255                 r = sd_device_monitor_filter_add_match_subsystem_devtype(monitor, subsystem, NULL);
 256                 if (r < 0)
 257                         return log_error_errno(r, "Failed to add %s subsystem match to monitor: %m", subsystem);
 258         }
 259
 260         r = sd_device_monitor_attach_event(monitor, event);
 261         if (r < 0)
 262                 return log_error_errno(r, "Failed to attach event to device monitor: %m");
 263
 264         r = sd_device_monitor_start(monitor, device_monitor_handler, &data);
 265         if (r < 0)
 266                 return log_error_errno(r, "Failed to start device monitor: %m");
 267
 268         if (deadline != USEC_INFINITY) {
 269                 r = sd_event_add_time(
 270                                 event, &timeout_source,
 271                                 CLOCK_MONOTONIC, deadline, 0,
 272                                 NULL, INT_TO_PTR(-ETIMEDOUT));
 273                 if (r < 0)
 274                         return log_error_errno(r, "Failed to add timeout event source: %m");
 275         }
 276
 277         /* Check again, maybe things changed. Udev will re-read the db if the device wasn't initialized
 278          * yet. */
 279         if (!device && devlink) {
 280                 r = device_new_from_dev_path(devlink, &device);
 281                 if (r < 0 && r != -ENOENT)
 282                         return r;
 283         }
 284         if (device && sd_device_get_is_initialized(device) > 0) {
 285                 if (ret)
 286                         *ret = sd_device_ref(device);
 287                 return 0;
 288         }
 289
 290         r = sd_event_loop(event);
 291         if (r < 0)
 292                 return log_error_errno(r, "Failed to wait for device to be initialized: %m");
 293
 294         if (ret)
 295                 *ret = TAKE_PTR(data.device);
 296         return 0;
 297 }
 298
 299 int device_wait_for_initialization(sd_device *device, const char *subsystem, usec_t deadline, sd_device **ret) {
 300         return device_wait_for_initialization_internal(device, NULL, subsystem, deadline, ret);
 301 }
 302
 303 int device_wait_for_devlink(const char *devlink, const char *subsystem, usec_t deadline, sd_device **ret) {
 304         return device_wait_for_initialization_internal(NULL, devlink, subsystem, deadline, ret);
 305 }
 306
 307 int device_is_renaming(sd_device *dev) {
 308         int r;
 309
 310         assert(dev);
 311
 312         r = sd_device_get_property_value(dev, "ID_RENAMING", NULL);
 313         if (r == -ENOENT)
 314                 return false;
 315         if (r < 0)
 316                 return r;
 317
 318         return true;
 319 }
 320
 321 bool device_for_action(sd_device *dev, DeviceAction action) {
 322         DeviceAction a;
 323
 324         assert(dev);
 325
 326         if (device_get_action(dev, &a) < 0)
 327                 return false;
 328
 329         return a == action;
 330 }
 331
 332 void log_device_uevent(sd_device *device, const char *str) {
 333         DeviceAction action = _DEVICE_ACTION_INVALID;
 334         uint64_t seqnum = 0;
 335
 336         if (!DEBUG_LOGGING)
 337                 return;
 338
 339         (void) device_get_seqnum(device, &seqnum);
 340         (void) device_get_action(device, &action);
 341         log_device_debug(device, "%s%s(SEQNUM=%"PRIu64", ACTION=%s)",
 342                          strempty(str), isempty(str) ? "" : " ",
 343                          seqnum, strna(device_action_to_string(action)));
 344 }
 345
 346 int udev_rule_parse_value(char *str, char **ret_value, char **ret_endpos) {
 347         char *i, *j;
 348         int r;
 349         bool is_escaped;
 350
 351         /* value must be double quotated */
 352         is_escaped = str[0] == 'e';
 353         str += is_escaped;
 354         if (str[0] != '"')
 355                 return -EINVAL;
 356         str++;
 357
 358         if (!is_escaped) {
 359                 /* unescape double quotation '\"'->'"' */
 360                 for (i = j = str; *i != '"'; i++, j++) {
 361                         if (*i == '\0')
 362                                 return -EINVAL;
 363                         if (i[0] == '\\' && i[1] == '"')
 364                                 i++;
 365                         *j = *i;
 366                 }
 367                 j[0] = '\0';
 368         } else {
 369                 _cleanup_free_ char *unescaped = NULL;
 370
 371                 /* find the end position of value */
 372                 for (i = str; *i != '"'; i++) {
 373                         if (i[0] == '\\')
 374                                 i++;
 375                         if (*i == '\0')
 376                                 return -EINVAL;
 377                 }
 378                 i[0] = '\0';
 379
 380                 r = cunescape_length(str, i - str, 0, &unescaped);
 381                 if (r < 0)
 382                         return r;
 383                 assert(r <= i - str);
 384                 memcpy(str, unescaped, r + 1);
 385         }
 386
 387         *ret_value = str;
 388         *ret_endpos = i + 1;
 389         return 0;
 390 }
 391
 392 size_t udev_replace_whitespace(const char *str, char *to, size_t len) {
 393         bool is_space = false;
 394         size_t i, j;
 395
 396         assert(str);
 397         assert(to);
 398
 399         /* Copy from 'str' to 'to', while removing all leading and trailing whitespace, and replacing
 400          * each run of consecutive whitespace with a single underscore. The chars from 'str' are copied
 401          * up to the \0 at the end of the string, or at most 'len' chars.  This appends \0 to 'to', at
 402          * the end of the copied characters.
 403          *
 404          * If 'len' chars are copied into 'to', the final \0 is placed at len+1 (i.e. 'to[len] = \0'),
 405          * so the 'to' buffer must have at least len+1 chars available.
 406          *
 407          * Note this may be called with 'str' == 'to', i.e. to replace whitespace in-place in a buffer.
 408          * This function can handle that situation.
 409          *
 410          * Note that only 'len' characters are read from 'str'. */
 411
 412         i = strspn(str, WHITESPACE);
 413
 414         for (j = 0; j < len && i < len && str[i] != '\0'; i++) {
 415                 if (isspace(str[i])) {
 416                         is_space = true;
 417                         continue;
 418                 }
 419
 420                 if (is_space) {
 421                         if (j + 1 >= len)
 422                                 break;
 423
 424                         to[j++] = '_';
 425                         is_space = false;
 426                 }
 427                 to[j++] = str[i];
 428         }
 429
 430         to[j] = '\0';
 431         return j;
 432 }
 433
 434 size_t udev_replace_chars(char *str, const char *allow) {
 435         size_t i = 0, replaced = 0;
 436
 437         assert(str);
 438
 439         /* allow chars in allow list, plain ascii, hex-escaping and valid utf8. */
 440
 441         while (str[i] != '\0') {
 442                 int len;
 443
 444                 if (allow_listed_char_for_devnode(str[i], allow)) {
 445                         i++;
 446                         continue;
 447                 }
 448
 449                 /* accept hex encoding */
 450                 if (str[i] == '\\' && str[i+1] == 'x') {
 451                         i += 2;
 452                         continue;
 453                 }
 454
 455                 /* accept valid utf8 */
 456                 len = utf8_encoded_valid_unichar(str + i, (size_t) -1);
 457                 if (len > 1) {
 458                         i += len;
 459                         continue;
 460                 }
 461
 462                 /* if space is allowed, replace whitespace with ordinary space */
 463                 if (isspace(str[i]) && allow && strchr(allow, ' ')) {
 464                         str[i] = ' ';
 465                         i++;
 466                         replaced++;
 467                         continue;
 468                 }
 469
 470                 /* everything else is replaced with '_' */
 471                 str[i] = '_';
 472                 i++;
 473                 replaced++;
 474         }
 475         return replaced;
 476 }
 477
 478 int udev_resolve_subsys_kernel(const char *string, char *result, size_t maxsize, bool read_value) {
 479         _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
 480         _cleanup_free_ char *temp = NULL;
 481         char *subsys, *sysname, *attr;
 482         const char *val;
 483         int r;
 484
 485         assert(string);
 486         assert(result);
 487
 488         /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
 489
 490         if (string[0] != '[')
 491                 return -EINVAL;
 492
 493         temp = strdup(string);
 494         if (!temp)
 495                 return -ENOMEM;
 496
 497         subsys = &temp[1];
 498
 499         sysname = strchr(subsys, '/');
 500         if (!sysname)
 501                 return -EINVAL;
 502         sysname[0] = '\0';
 503         sysname = &sysname[1];
 504
 505         attr = strchr(sysname, ']');
 506         if (!attr)
 507                 return -EINVAL;
 508         attr[0] = '\0';
 509         attr = &attr[1];
 510         if (attr[0] == '/')
 511                 attr = &attr[1];
 512         if (attr[0] == '\0')
 513                 attr = NULL;
 514
 515         if (read_value && !attr)
 516                 return -EINVAL;
 517
 518         r = sd_device_new_from_subsystem_sysname(&dev, subsys, sysname);
 519         if (r < 0)
 520                 return r;
 521
 522         if (read_value) {
 523                 r = sd_device_get_sysattr_value(dev, attr, &val);
 524                 if (r < 0 && r != -ENOENT)
 525                         return r;
 526                 if (r == -ENOENT)
 527                         result[0] = '\0';
 528                 else
 529                         strscpy(result, maxsize, val);
 530                 log_debug("value '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
 531         } else {
 532                 r = sd_device_get_syspath(dev, &val);
 533                 if (r < 0)
 534                         return r;
 535
 536                 strscpyl(result, maxsize, val, attr ? "/" : NULL, attr ?: NULL, NULL);
 537                 log_debug("path '[%s/%s]%s' is '%s'", subsys, sysname, strempty(attr), result);
 538         }
 539         return 0;
 540 }
 541
 542 int udev_queue_is_empty(void) {
 543         return access("/run/udev/queue", F_OK) < 0 ?
 544                 (errno == ENOENT ? true : -errno) : false;
 545 }
 546
 547 int udev_queue_init(void) {
 548         _cleanup_close_ int fd = -1;
 549
 550         fd = inotify_init1(IN_CLOEXEC);
 551         if (fd < 0)
 552                 return -errno;
 553
 554         if (inotify_add_watch(fd, "/run/udev" , IN_DELETE) < 0)
 555                 return -errno;
 556
 557         return TAKE_FD(fd);
 558 }