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-private.h"
  11 #include "device-util.h"
  12 #include "env-file.h"
  13 #include "errno-util.h"
  14 #include "escape.h"
  15 #include "fd-util.h"
  16 #include "log.h"
  17 #include "macro.h"
  18 #include "parse-util.h"
  19 #include "path-util.h"
  20 #include "signal-util.h"
  21 #include "socket-util.h"
  22 #include "string-table.h"
  23 #include "string-util.h"
  24 #include "strxcpyx.h"
  25 #include "udev-util.h"
  26 #include "utf8.h"
  27
  28 static const char* const resolve_name_timing_table[_RESOLVE_NAME_TIMING_MAX] = {
  29         [RESOLVE_NAME_NEVER] = "never",
  30         [RESOLVE_NAME_LATE] = "late",
  31         [RESOLVE_NAME_EARLY] = "early",
  32 };
  33
  34 DEFINE_STRING_TABLE_LOOKUP(resolve_name_timing, ResolveNameTiming);
  35
  36 int udev_parse_config_full(
  37                 unsigned *ret_children_max,
  38                 usec_t *ret_exec_delay_usec,
  39                 usec_t *ret_event_timeout_usec,
  40                 ResolveNameTiming *ret_resolve_name_timing,
  41                 int *ret_timeout_signal) {
  42
  43         _cleanup_free_ char *log_val = NULL, *children_max = NULL, *exec_delay = NULL, *event_timeout = NULL, *resolve_names = NULL, *timeout_signal = NULL;
  44         int r;
  45
  46         r = parse_env_file(NULL, "/etc/udev/udev.conf",
  47                            "udev_log", &log_val,
  48                            "children_max", &children_max,
  49                            "exec_delay", &exec_delay,
  50                            "event_timeout", &event_timeout,
  51                            "resolve_names", &resolve_names,
  52                            "timeout_signal", &timeout_signal);
  53         if (r == -ENOENT)
  54                 return 0;
  55         if (r < 0)
  56                 return r;
  57
  58         if (log_val) {
  59                 const char *log;
  60                 size_t n;
  61
  62                 /* unquote */
  63                 n = strlen(log_val);
  64                 if (n >= 2 &&
  65                     ((log_val[0] == '"' && log_val[n-1] == '"') ||
  66                      (log_val[0] == '\'' && log_val[n-1] == '\''))) {
  67                         log_val[n - 1] = '\0';
  68                         log = log_val + 1;
  69                 } else
  70                         log = log_val;
  71
  72                 /* we set the udev log level here explicitly, this is supposed
  73                  * to regulate the code in libudev/ and udev/. */
  74                 r = log_set_max_level_from_string(log);
  75                 if (r < 0)
  76                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  77                                    "failed to set udev log level '%s', ignoring: %m", log);
  78         }
  79
  80         if (ret_children_max && children_max) {
  81                 r = safe_atou(children_max, ret_children_max);
  82                 if (r < 0)
  83                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  84                                    "failed to parse children_max=%s, ignoring: %m", children_max);
  85         }
  86
  87         if (ret_exec_delay_usec && exec_delay) {
  88                 r = parse_sec(exec_delay, ret_exec_delay_usec);
  89                 if (r < 0)
  90                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  91                                    "failed to parse exec_delay=%s, ignoring: %m", exec_delay);
  92         }
  93
  94         if (ret_event_timeout_usec && event_timeout) {
  95                 r = parse_sec(event_timeout, ret_event_timeout_usec);
  96                 if (r < 0)
  97                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
  98                                    "failed to parse event_timeout=%s, ignoring: %m", event_timeout);
  99         }
 100
 101         if (ret_resolve_name_timing && resolve_names) {
 102                 ResolveNameTiming t;
 103
 104                 t = resolve_name_timing_from_string(resolve_names);
 105                 if (t < 0)
 106                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
 107                                    "failed to parse resolve_names=%s, ignoring.", resolve_names);
 108                 else
 109                         *ret_resolve_name_timing = t;
 110         }
 111
 112         if (ret_timeout_signal && timeout_signal) {
 113                 r = signal_from_string(timeout_signal);
 114                 if (r < 0)
 115                         log_syntax(NULL, LOG_WARNING, "/etc/udev/udev.conf", 0, r,
 116                                    "failed to parse timeout_signal=%s, ignoring: %m", timeout_signal);
 117                 else
 118                         *ret_timeout_signal = r;
 119         }
 120
 121         return 0;
 122 }
 123
 124 /* Note that if -ENOENT is returned, it will be logged at debug level rather than error,
 125  * because it's an expected, common occurrence that the caller will handle with a fallback */
 126 static int device_new_from_dev_path(const char *devlink, sd_device **ret_device) {
 127         struct stat st;
 128         int r;
 129
 130         assert(devlink);
 131
 132         if (stat(devlink, &st) < 0)
 133                 return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno,
 134                                       "Failed to stat() %s: %m", devlink);
 135
 136         if (!S_ISBLK(st.st_mode))
 137                 return log_error_errno(SYNTHETIC_ERRNO(ENOTBLK),
 138                                        "%s does not point to a block device: %m", devlink);
 139
 140         r = sd_device_new_from_stat_rdev(ret_device, &st);
 141         if (r < 0)
 142                 return log_error_errno(r, "Failed to initialize device from %s: %m", devlink);
 143
 144         return 0;
 145 }
 146
 147 struct DeviceMonitorData {
 148         const char *sysname;
 149         const char *devlink;
 150         sd_device *device;
 151 };
 152
 153 static void device_monitor_data_free(struct DeviceMonitorData *d) {
 154         assert(d);
 155
 156         sd_device_unref(d->device);
 157 }
 158
 159 static int device_monitor_handler(sd_device_monitor *monitor, sd_device *device, void *userdata) {
 160         struct DeviceMonitorData *data = userdata;
 161         const char *sysname;
 162
 163         assert(device);
 164         assert(data);
 165         assert(data->sysname || data->devlink);
 166         assert(!data->device);
 167
 168         /* Ignore REMOVE events here. We are waiting for initialization after all, not de-initialization. We
 169          * might see a REMOVE event from an earlier use of the device (devices by the same name are recycled
 170          * by the kernel after all), which we should not get confused by. After all we cannot distinguish use
 171          * cycles of the devices, as the udev queue is entirely asynchronous.
 172          *
 173          * If we see a REMOVE event here for the use cycle we actually care about then we won't notice of
 174          * course, but that should be OK, given the timeout logic used on the wait loop: this will be noticed
 175          * by means of -ETIMEDOUT. Thus we won't notice immediately, but eventually, and that should be
 176          * sufficient for an error path that should regularly not happen.
 177          *
 178          * (And yes, we only need to special case REMOVE. It's the only "negative" event type, where a device
 179          * ceases to exist. All other event types are "positive": the device exists and is registered in the
 180          * udev database, thus whenever we see the event, we can consider it initialized.) */
 181         if (device_for_action(device, SD_DEVICE_REMOVE))
 182                 return 0;
 183
 184         if (data->sysname && sd_device_get_sysname(device, &sysname) >= 0 && streq(sysname, data->sysname))
 185                 goto found;
 186
 187         if (data->devlink) {
 188                 const char *devlink;
 189
 190                 FOREACH_DEVICE_DEVLINK(device, devlink)
 191                         if (path_equal(devlink, data->devlink))
 192                                 goto found;
 193
 194                 if (sd_device_get_devname(device, &devlink) >= 0 && path_equal(devlink, data->devlink))
 195                         goto found;
 196         }
 197
 198         return 0;
 199
 200 found:
 201         data->device = sd_device_ref(device);
 202         return sd_event_exit(sd_device_monitor_get_event(monitor), 0);
 203 }
 204
 205 static int device_wait_for_initialization_internal(
 206                 sd_device *_device,
 207                 const char *devlink,
 208                 const char *subsystem,
 209                 usec_t deadline,
 210                 sd_device **ret) {
 211
 212         _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *monitor = NULL;
 213         _cleanup_(sd_event_source_unrefp) sd_event_source *timeout_source = NULL;
 214         _cleanup_(sd_event_unrefp) sd_event *event = NULL;
 215         /* Ensure that if !_device && devlink, device gets unrefd on errors since it will be new */
 216         _cleanup_(sd_device_unrefp) sd_device *device = sd_device_ref(_device);
 217         _cleanup_(device_monitor_data_free) struct DeviceMonitorData data = {
 218                 .devlink = devlink,
 219         };
 220         int r;
 221
 222         assert(device || (subsystem && devlink));
 223
 224         /* Devlink might already exist, if it does get the device to use the sysname filtering */
 225         if (!device && devlink) {
 226                 r = device_new_from_dev_path(devlink, &device);
 227                 if (r < 0 && r != -ENOENT)
 228                         return r;
 229         }
 230
 231         if (device) {
 232                 if (sd_device_get_is_initialized(device) > 0) {
 233                         if (ret)
 234                                 *ret = sd_device_ref(device);
 235                         return 0;
 236                 }
 237                 /* We need either the sysname or the devlink for filtering */
 238                 assert_se(sd_device_get_sysname(device, &data.sysname) >= 0 || devlink);
 239         }
 240
 241         /* Wait until the device is initialized, so that we can get access to the ID_PATH property */
 242
 243         r = sd_event_new(&event);
 244         if (r < 0)
 245                 return log_error_errno(r, "Failed to get default event: %m");
 246
 247         r = sd_device_monitor_new(&monitor);
 248         if (r < 0)
 249                 return log_error_errno(r, "Failed to acquire monitor: %m");
 250
 251         if (device && !subsystem) {
 252                 r = sd_device_get_subsystem(device, &subsystem);
 253                 if (r < 0 && r != -ENOENT)
 254                         return log_device_error_errno(device, r, "Failed to get subsystem: %m");
 255         }
 256
 257         if (subsystem) {
 258                 r = sd_device_monitor_filter_add_match_subsystem_devtype(monitor, subsystem, NULL);
 259                 if (r < 0)
 260                         return log_error_errno(r, "Failed to add %s subsystem match to monitor: %m", subsystem);
 261         }
 262
 263         r = sd_device_monitor_attach_event(monitor, event);
 264         if (r < 0)
 265                 return log_error_errno(r, "Failed to attach event to device monitor: %m");
 266
 267         r = sd_device_monitor_start(monitor, device_monitor_handler, &data);
 268         if (r < 0)
 269                 return log_error_errno(r, "Failed to start device monitor: %m");
 270
 271         if (deadline != USEC_INFINITY) {
 272                 r = sd_event_add_time(
 273                                 event, &timeout_source,
 274                                 CLOCK_MONOTONIC, deadline, 0,
 275                                 NULL, INT_TO_PTR(-ETIMEDOUT));
 276                 if (r < 0)
 277                         return log_error_errno(r, "Failed to add timeout event source: %m");
 278         }
 279
 280         /* Check again, maybe things changed. Udev will re-read the db if the device wasn't initialized
 281          * yet. */
 282         if (!device && devlink) {
 283                 r = device_new_from_dev_path(devlink, &device);
 284                 if (r < 0 && r != -ENOENT)
 285                         return r;
 286         }
 287         if (device && sd_device_get_is_initialized(device) > 0) {
 288                 if (ret)
 289                         *ret = sd_device_ref(device);
 290                 return 0;
 291         }
 292
 293         r = sd_event_loop(event);
 294         if (r < 0)
 295                 return log_error_errno(r, "Failed to wait for device to be initialized: %m");
 296
 297         if (ret)
 298                 *ret = TAKE_PTR(data.device);
 299         return 0;
 300 }
 301
 302 int device_wait_for_initialization(sd_device *device, const char *subsystem, usec_t deadline, sd_device **ret) {
 303         return device_wait_for_initialization_internal(device, NULL, subsystem, deadline, ret);
 304 }
 305
 306 int device_wait_for_devlink(const char *devlink, const char *subsystem, usec_t deadline, sd_device **ret) {
 307         return device_wait_for_initialization_internal(NULL, devlink, subsystem, deadline, ret);
 308 }
 309
 310 int device_is_renaming(sd_device *dev) {
 311         int r;
 312
 313         assert(dev);
 314
 315         r = sd_device_get_property_value(dev, "ID_RENAMING", NULL);
 316         if (r == -ENOENT)
 317                 return false;
 318         if (r < 0)
 319                 return r;
 320
 321         return true;
 322 }
 323
 324 bool device_for_action(sd_device *dev, sd_device_action_t a) {
 325         sd_device_action_t b;
 326
 327         assert(dev);
 328
 329         if (a < 0)
 330                 return false;
 331
 332         if (sd_device_get_action(dev, &b) < 0)
 333                 return false;
 334
 335         return a == b;
 336 }
 337
 338 void log_device_uevent(sd_device *device, const char *str) {
 339         sd_device_action_t action = _SD_DEVICE_ACTION_INVALID;
 340         uint64_t seqnum = 0;
 341
 342         if (!DEBUG_LOGGING)
 343                 return;
 344
 345         (void) sd_device_get_seqnum(device, &seqnum);
 346         (void) sd_device_get_action(device, &action);
 347         log_device_debug(device, "%s%s(SEQNUM=%"PRIu64", ACTION=%s)",
 348                          strempty(str), isempty(str) ? "" : " ",
 349                          seqnum, strna(device_action_to_string(action)));
 350 }
 351
 352 int udev_rule_parse_value(char *str, char **ret_value, char **ret_endpos) {
 353         char *i, *j;
 354         bool is_escaped;
 355
 356         /* value must be double quotated */
 357         is_escaped = str[0] == 'e';
 358         str += is_escaped;
 359         if (str[0] != '"')
 360                 return -EINVAL;
 361         str++;
 362
 363         if (!is_escaped) {
 364                 /* unescape double quotation '\"'->'"' */
 365                 for (i = j = str; *i != '"'; i++, j++) {
 366                         if (*i == '\0')
 367                                 return -EINVAL;
 368                         if (i[0] == '\\' && i[1] == '"')
 369                                 i++;
 370                         *j = *i;
 371                 }
 372                 j[0] = '\0';
 373         } else {
 374                 _cleanup_free_ char *unescaped = NULL;
 375                 ssize_t l;
 376
 377                 /* find the end position of value */
 378                 for (i = str; *i != '"'; i++) {
 379                         if (i[0] == '\\')
 380                                 i++;
 381                         if (*i == '\0')
 382                                 return -EINVAL;
 383                 }
 384                 i[0] = '\0';
 385
 386                 l = cunescape_length(str, i - str, 0, &unescaped);
 387                 if (l < 0)
 388                         return l;
 389
 390                 assert(l <= i - str);
 391                 memcpy(str, unescaped, l + 1);
 392         }
 393
 394         *ret_value = str;
 395         *ret_endpos = i + 1;
 396         return 0;
 397 }
 398
 399 size_t udev_replace_whitespace(const char *str, char *to, size_t len) {
 400         bool is_space = false;
 401         size_t i, j;
 402
 403         assert(str);
 404         assert(to);
 405
 406         /* Copy from 'str' to 'to', while removing all leading and trailing whitespace, and replacing
 407          * each run of consecutive whitespace with a single underscore. The chars from 'str' are copied
 408          * up to the \0 at the end of the string, or at most 'len' chars.  This appends \0 to 'to', at
 409          * the end of the copied characters.
 410          *
 411          * If 'len' chars are copied into 'to', the final \0 is placed at len+1 (i.e. 'to[len] = \0'),
 412          * so the 'to' buffer must have at least len+1 chars available.
 413          *
 414          * Note this may be called with 'str' == 'to', i.e. to replace whitespace in-place in a buffer.
 415          * This function can handle that situation.
 416          *
 417          * Note that only 'len' characters are read from 'str'. */
 418
 419         i = strspn(str, WHITESPACE);
 420
 421         for (j = 0; j < len && i < len && str[i] != '\0'; i++) {
 422                 if (isspace(str[i])) {
 423                         is_space = true;
 424                         continue;
 425                 }
 426
 427                 if (is_space) {
 428                         if (j + 1 >= len)
 429                                 break;
 430
 431                         to[j++] = '_';
 432                         is_space = false;
 433                 }
 434                 to[j++] = str[i];
 435         }
 436
 437         to[j] = '\0';
 438         return j;
 439 }
 440
 441 size_t udev_replace_ifname(char *str) {
 442         size_t replaced = 0;
 443
 444         assert(str);
 445
 446         /* See ifname_valid_full(). */
 447
 448         for (char *p = str; *p != '\0'; p++)
 449                 if (!ifname_valid_char(*p)) {
 450                         *p = '_';
 451                         replaced++;
 452                 }
 453
 454         return replaced;
 455 }
 456
 457 size_t udev_replace_chars(char *str, const char *allow) {
 458         size_t i = 0, replaced = 0;
 459
 460         assert(str);
 461
 462         /* allow chars in allow list, plain ascii, hex-escaping and valid utf8. */
 463
 464         while (str[i] != '\0') {
 465                 int len;
 466
 467                 if (allow_listed_char_for_devnode(str[i], allow)) {
 468                         i++;
 469                         continue;
 470                 }
 471
 472                 /* accept hex encoding */
 473                 if (str[i] == '\\' && str[i+1] == 'x') {
 474                         i += 2;
 475                         continue;
 476                 }
 477
 478                 /* accept valid utf8 */
 479                 len = utf8_encoded_valid_unichar(str + i, SIZE_MAX);
 480                 if (len > 1) {
 481                         i += len;
 482                         continue;
 483                 }
 484
 485                 /* if space is allowed, replace whitespace with ordinary space */
 486                 if (isspace(str[i]) && allow && strchr(allow, ' ')) {
 487                         str[i] = ' ';
 488                         i++;
 489                         replaced++;
 490                         continue;
 491                 }
 492
 493                 /* everything else is replaced with '_' */
 494                 str[i] = '_';
 495                 i++;
 496                 replaced++;
 497         }
 498         return replaced;
 499 }
 500
 501 int udev_resolve_subsys_kernel(const char *string, char *result, size_t maxsize, bool read_value) {
 502         _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
 503         _cleanup_free_ char *temp = NULL;
 504         char *subsys, *sysname, *attr;
 505         const char *val;
 506         int r;
 507
 508         assert(string);
 509         assert(result);
 510
 511         /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
 512
 513         if (string[0] != '[')
 514                 return -EINVAL;
 515
 516         temp = strdup(string);
 517         if (!temp)
 518                 return -ENOMEM;
 519
 520         subsys = &temp[1];
 521
 522         sysname = strchr(subsys, '/');
 523         if (!sysname)
 524                 return -EINVAL;
 525         sysname[0] = '\0';
 526         sysname = &sysname[1];
 527
 528         attr = strchr(sysname, ']');
 529         if (!attr)
 530                 return -EINVAL;
 531         attr[0] = '\0';
 532         attr = &attr[1];
 533         if (attr[0] == '/')
 534                 attr = &attr[1];
 535         if (attr[0] == '\0')
 536                 attr = NULL;
 537
 538         if (read_value && !attr)
 539                 return -EINVAL;
 540
 541         r = sd_device_new_from_subsystem_sysname(&dev, subsys, sysname);
 542         if (r < 0)
 543                 return r;
 544
 545         if (read_value) {
 546                 r = sd_device_get_sysattr_value(dev, attr, &val);
 547                 if (r < 0 && !ERRNO_IS_PRIVILEGE(r) && r != -ENOENT)
 548                         return r;
 549                 if (r >= 0)
 550                         strscpy(result, maxsize, val);
 551                 else
 552                         result[0] = '\0';
 553                 log_debug("value '[%s/%s]%s' is '%s'", subsys, sysname, attr, result);
 554         } else {
 555                 r = sd_device_get_syspath(dev, &val);
 556                 if (r < 0)
 557                         return r;
 558
 559                 strscpyl(result, maxsize, val, attr ? "/" : NULL, attr ?: NULL, NULL);
 560                 log_debug("path '[%s/%s]%s' is '%s'", subsys, sysname, strempty(attr), result);
 561         }
 562         return 0;
 563 }
 564
 565 int udev_queue_is_empty(void) {
 566         return access("/run/udev/queue", F_OK) < 0 ?
 567                 (errno == ENOENT ? true : -errno) : false;
 568 }
 569
 570 int udev_queue_init(void) {
 571         _cleanup_close_ int fd = -1;
 572
 573         fd = inotify_init1(IN_CLOEXEC);
 574         if (fd < 0)
 575                 return -errno;
 576
 577         if (inotify_add_watch(fd, "/run/udev" , IN_DELETE) < 0)
 578                 return -errno;
 579
 580         return TAKE_FD(fd);
 581 }