util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * mdev - Mini udev for busybox
   4  *
   5  * Copyright 2005 Rob Landley <rob@landley.net>
   6  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   7  *
   8  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
   9  */
  10 #include "libbb.h"
  11 #include "xregex.h"
  12
  13 struct globals {
  14         int root_major, root_minor;
  15         char *subsystem;
  16 };
  17 #define G (*(struct globals*)&bb_common_bufsiz1)
  18 #define root_major (G.root_major)
  19 #define root_minor (G.root_minor)
  20 #define subsystem (G.subsystem)
  21
  22 /* Prevent infinite loops in /sys symlinks */
  23 #define MAX_SYSFS_DEPTH 3
  24
  25 /* We use additional 64+ bytes in make_device() */
  26 #define SCRATCH_SIZE 80
  27
  28 #if ENABLE_FEATURE_MDEV_RENAME
  29 /* Builds an alias path.
  30  * This function potentionally reallocates the alias parameter.
  31  */
  32 static char *build_alias(char *alias, const char *device_name)
  33 {
  34         char *dest;
  35
  36         /* ">bar/": rename to bar/device_name */
  37         /* ">bar[/]baz": rename to bar[/]baz */
  38         dest = strrchr(alias, '/');
  39         if (dest) { /* ">bar/[baz]" ? */
  40                 *dest = '\0'; /* mkdir bar */
  41                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
  42                 *dest = '/';
  43                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
  44                         dest = alias;
  45                         alias = concat_path_file(alias, device_name);
  46                         free(dest);
  47                 }
  48         }
  49
  50         return alias;
  51 }
  52 #endif
  53
  54 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  55 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  56 static void make_device(char *path, int delete)
  57 {
  58 #if ENABLE_FEATURE_MDEV_CONF
  59         parser_t *parser;
  60 #endif
  61         const char *device_name;
  62         int major, minor, type, len;
  63         int mode;
  64         char *dev_maj_min = path + strlen(path);
  65
  66         /* Force the configuration file settings exactly. */
  67         umask(0);
  68
  69         /* Try to read major/minor string.  Note that the kernel puts \n after
  70          * the data, so we don't need to worry about null terminating the string
  71          * because sscanf() will stop at the first nondigit, which \n is.
  72          * We also depend on path having writeable space after it.
  73          */
  74         major = -1;
  75         if (!delete) {
  76                 strcpy(dev_maj_min, "/dev");
  77                 len = open_read_close(path, dev_maj_min + 1, 64);
  78                 *dev_maj_min++ = '\0';
  79                 if (len < 1) {
  80                         if (!ENABLE_FEATURE_MDEV_EXEC)
  81                                 return;
  82                         /* no "dev" file, so just try to run script */
  83                         *dev_maj_min = '\0';
  84                 } else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
  85                         major = -1;
  86                 }
  87         }
  88
  89         /* Determine device name, type, major and minor */
  90         device_name = bb_basename(path);
  91         /* http://kernel.org/doc/pending/hotplug.txt says that only
  92          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
  93          * But since 2.6.25 block devices are also in /sys/class/block.
  94          * We use strstr("/block/") to forestall future surprises. */
  95         type = S_IFCHR;
  96         if (strstr(path, "/block/"))
  97                 type = S_IFBLK;
  98
  99 #if !ENABLE_FEATURE_MDEV_CONF
 100         mode = 0660;
 101 #else
 102         /* If we have config file, look up user settings */
 103         parser = config_open2("/etc/mdev.conf", fopen_for_read);
 104         while (1) {
 105                 regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 106                 int keep_matching;
 107                 char *val;
 108                 struct bb_uidgid_t ugid;
 109                 char *tokens[4];
 110 # if ENABLE_FEATURE_MDEV_EXEC
 111                 char *command = NULL;
 112 # endif
 113 # if ENABLE_FEATURE_MDEV_RENAME
 114                 char *alias = NULL;
 115                 char aliaslink = aliaslink; /* for compiler */
 116 # endif
 117                 /* Defaults in case we won't match any line */
 118                 ugid.uid = ugid.gid = 0;
 119                 keep_matching = 0;
 120                 mode = 0660;
 121
 122                 if (!config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
 123                         /* End of file, create dev node with default params */
 124                         goto line_matches;
 125                 }
 126
 127                 val = tokens[0];
 128                 keep_matching = ('-' == val[0]);
 129                 val += keep_matching; /* swallow leading dash */
 130
 131                 /* Fields: regex uid:gid mode [alias] [cmd] */
 132
 133                 /* 1st field: @<numeric maj,min>... */
 134                 if (val[0] == '@') {
 135                         /* @major,minor[-last] */
 136                         /* (useful when name is ambiguous:
 137                          * "/sys/class/usb/lp0" and
 138                          * "/sys/class/printer/lp0") */
 139                         int cmaj, cmin0, cmin1, sc;
 140                         if (major < 0)
 141                                 continue; /* no dev, no match */
 142                         sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
 143                         if (sc < 1 || major != cmaj
 144                          || (sc == 2 && minor != cmin0)
 145                          || (sc == 3 && (minor < cmin0 || minor > cmin1))
 146                         ) {
 147                                 continue; /* this line doesn't match */
 148                         }
 149                 } else { /* ... or regex to match device name */
 150                         regex_t match;
 151                         int result;
 152                         const char *dev_name_or_subsystem = device_name;
 153                         if ('/' == val[0] && subsystem) {
 154                                 dev_name_or_subsystem = subsystem;
 155                                 val++;
 156                         }
 157
 158                         /* Is this it? */
 159                         xregcomp(&match, val, REG_EXTENDED);
 160                         result = regexec(&match, dev_name_or_subsystem, ARRAY_SIZE(off), off, 0);
 161                         regfree(&match);
 162
 163                         //bb_error_msg("matches:");
 164                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 165                         //      if (off[i].rm_so < 0) continue;
 166                         //      bb_error_msg("match %d: '%.*s'\n", i,
 167                         //              (int)(off[i].rm_eo - off[i].rm_so),
 168                         //              device_name + off[i].rm_so);
 169                         //}
 170
 171                         /* If not this device, skip rest of line */
 172                         /* (regexec returns whole pattern as "range" 0) */
 173                         if (result || off[0].rm_so
 174                          || ((int)off[0].rm_eo != (int)strlen(dev_name_or_subsystem))
 175                         ) {
 176                                 continue; /* this line doesn't match */
 177                         }
 178                 }
 179
 180                 /* This line matches: stop parsing the file after parsing
 181                  * the rest of fields unless keep_matching == 1 */
 182
 183                 /* 2nd field: uid:gid - device ownership */
 184                 if (get_uidgid(&ugid, tokens[1], 1) == 0)
 185                         bb_error_msg("unknown user/group %s", tokens[1]);
 186
 187                 /* 3rd field: mode - device permissions */
 188                 mode = strtoul(tokens[2], NULL, 8);
 189
 190                 val = tokens[3];
 191                 /* 4th field (opt): >|=alias */
 192 # if ENABLE_FEATURE_MDEV_RENAME
 193                 if (!val)
 194                         goto line_matches;
 195                 aliaslink = val[0];
 196                 if (aliaslink == '>' || aliaslink == '=') {
 197                         char *a, *s, *st;
 198 #  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 199                         char *p;
 200                         unsigned i, n;
 201 #  endif
 202                         a = val;
 203                         s = strchrnul(val, ' ');
 204                         st = strchrnul(val, '\t');
 205                         if (st < s)
 206                                 s = st;
 207                         val = (s[0] && s[1]) ? s+1 : NULL;
 208                         s[0] = '\0';
 209
 210 #  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 211                         /* substitute %1..9 with off[1..9], if any */
 212                         n = 0;
 213                         s = a;
 214                         while (*s)
 215                                 if (*s++ == '%')
 216                                         n++;
 217
 218                         p = alias = xzalloc(strlen(a) + n * strlen(device_name));
 219                         s = a + 1;
 220                         while (*s) {
 221                                 *p = *s;
 222                                 if ('%' == *s) {
 223                                         i = (s[1] - '0');
 224                                         if (i <= 9 && off[i].rm_so >= 0) {
 225                                                 n = off[i].rm_eo - off[i].rm_so;
 226                                                 strncpy(p, device_name + off[i].rm_so, n);
 227                                                 p += n - 1;
 228                                                 s++;
 229                                         }
 230                                 }
 231                                 p++;
 232                                 s++;
 233                         }
 234 #  else
 235                         alias = xstrdup(a + 1);
 236 #  endif
 237                 }
 238 # endif /* ENABLE_FEATURE_MDEV_RENAME */
 239
 240 # if ENABLE_FEATURE_MDEV_EXEC
 241                 /* The rest (opt): @|$|*command */
 242                 if (!val)
 243                         goto line_matches;
 244                 {
 245                         const char *s = "@$*";
 246                         const char *s2 = strchr(s, val[0]);
 247
 248                         if (!s2)
 249                                 bb_error_msg_and_die("bad line %u", parser->lineno);
 250
 251                         /* Correlate the position in the "@$*" with the delete
 252                          * step so that we get the proper behavior:
 253                          * @cmd: run on create
 254                          * $cmd: run on delete
 255                          * *cmd: run on both
 256                          */
 257                         if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 258                                 command = xstrdup(val + 1);
 259                         }
 260                 }
 261 # endif
 262                 /* End of field parsing */
 263  line_matches:
 264 #endif /* ENABLE_FEATURE_MDEV_CONF */
 265
 266                 /* "Execute" the line we found */
 267
 268                 if (!delete && major >= 0) {
 269                         if (ENABLE_FEATURE_MDEV_RENAME)
 270                                 unlink(device_name);
 271                         if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 272                                 bb_perror_msg_and_die("mknod %s", device_name);
 273                         if (major == root_major && minor == root_minor)
 274                                 symlink(device_name, "root");
 275 #if ENABLE_FEATURE_MDEV_CONF
 276                         chown(device_name, ugid.uid, ugid.gid);
 277 # if ENABLE_FEATURE_MDEV_RENAME
 278                         if (alias) {
 279                                 alias = build_alias(alias, device_name);
 280                                 /* move the device, and optionally
 281                                  * make a symlink to moved device node */
 282                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 283                                         symlink(alias, device_name);
 284                                 free(alias);
 285                         }
 286 # endif
 287 #endif
 288                 }
 289 #if ENABLE_FEATURE_MDEV_EXEC
 290                 if (command) {
 291                         /* setenv will leak memory, use putenv/unsetenv/free */
 292                         char *s = xasprintf("%s=%s", "MDEV", device_name);
 293                         char *s1 = xasprintf("%s=%s", "SUBSYSTEM", subsystem);
 294                         putenv(s);
 295                         putenv(s1);
 296                         if (system(command) == -1)
 297                                 bb_perror_msg_and_die("can't run '%s'", command);
 298                         unsetenv("SUBSYSTEM");
 299                         free(s1);
 300                         unsetenv("MDEV");
 301                         free(s);
 302                         free(command);
 303                 }
 304 #endif
 305                 if (delete) {
 306                         unlink(device_name);
 307                         /* At creation time, device might have been moved
 308                          * and a symlink might have been created. Undo that. */
 309 #if ENABLE_FEATURE_MDEV_RENAME
 310                         if (alias) {
 311                                 alias = build_alias(alias, device_name);
 312                                 unlink(alias);
 313                                 free(alias);
 314                         }
 315 #endif
 316                 }
 317
 318 #if ENABLE_FEATURE_MDEV_CONF
 319                 /* We found matching line.
 320                  * Stop unless it was prefixed with '-' */
 321                 if (!keep_matching)
 322                         break;
 323         } /* end of "while line is read from /etc/mdev.conf" */
 324
 325         config_close(parser);
 326 #endif /* ENABLE_FEATURE_MDEV_CONF */
 327 }
 328
 329 /* File callback for /sys/ traversal */
 330 static int FAST_FUNC fileAction(const char *fileName,
 331                 struct stat *statbuf UNUSED_PARAM,
 332                 void *userData,
 333                 int depth UNUSED_PARAM)
 334 {
 335         size_t len = strlen(fileName) - 4; /* can't underflow */
 336         char *scratch = userData;
 337
 338         /* len check is for paranoid reasons */
 339         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 340                 return FALSE;
 341
 342         strcpy(scratch, fileName);
 343         scratch[len] = '\0';
 344         make_device(scratch, 0);
 345
 346         return TRUE;
 347 }
 348
 349 /* Directory callback for /sys/ traversal */
 350 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 351                 struct stat *statbuf UNUSED_PARAM,
 352                 void *userData UNUSED_PARAM,
 353                 int depth)
 354 {
 355         /* Extract device subsystem -- the name of the directory
 356          * under /sys/class/ */
 357         if (1 == depth) {
 358                 free(subsystem);
 359                 subsystem = strrchr(fileName, '/');
 360                 if (subsystem)
 361                         subsystem = xstrdup(subsystem + 1);
 362         }
 363
 364         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 365 }
 366
 367 /* For the full gory details, see linux/Documentation/firmware_class/README
 368  *
 369  * Firmware loading works like this:
 370  * - kernel sets FIRMWARE env var
 371  * - userspace checks /lib/firmware/$FIRMWARE
 372  * - userspace waits for /sys/$DEVPATH/loading to appear
 373  * - userspace writes "1" to /sys/$DEVPATH/loading
 374  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 375  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 376  * - kernel loads firmware into device
 377  */
 378 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 379 {
 380         int cnt;
 381         int firmware_fd, loading_fd, data_fd;
 382
 383         /* check for /lib/firmware/$FIRMWARE */
 384         xchdir("/lib/firmware");
 385         firmware_fd = xopen(firmware, O_RDONLY);
 386
 387         /* in case we goto out ... */
 388         data_fd = -1;
 389
 390         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 391         xchdir(sysfs_path);
 392         for (cnt = 0; cnt < 30; ++cnt) {
 393                 loading_fd = open("loading", O_WRONLY);
 394                 if (loading_fd != -1)
 395                         goto loading;
 396                 sleep(1);
 397         }
 398         goto out;
 399
 400  loading:
 401         /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 402         if (full_write(loading_fd, "1", 1) != 1)
 403                 goto out;
 404
 405         /* load firmware into /sys/$DEVPATH/data */
 406         data_fd = open("data", O_WRONLY);
 407         if (data_fd == -1)
 408                 goto out;
 409         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 410
 411         /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
 412         if (cnt > 0)
 413                 full_write(loading_fd, "0", 1);
 414         else
 415                 full_write(loading_fd, "-1", 2);
 416
 417  out:
 418         if (ENABLE_FEATURE_CLEAN_UP) {
 419                 close(firmware_fd);
 420                 close(loading_fd);
 421                 close(data_fd);
 422         }
 423 }
 424
 425 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 426 int mdev_main(int argc UNUSED_PARAM, char **argv)
 427 {
 428         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 429
 430         /* We can be called as hotplug helper */
 431         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 432 #if 1
 433         bb_sanitize_stdio();
 434 #else
 435         /* Debug code */
 436         /* Replace LOGFILE by other file or device name if you need */
 437 #define LOGFILE "/dev/console"
 438         /* Just making sure fd 0 is not closed,
 439          * we don't really intend to read from it */
 440         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 441         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 442         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 443 #endif
 444
 445         xchdir("/dev");
 446
 447         if (argv[1] && strcmp(argv[1], "-s") == 0) {
 448                 /* Scan:
 449                  * mdev -s
 450                  */
 451                 struct stat st;
 452
 453                 xstat("/", &st);
 454                 root_major = major(st.st_dev);
 455                 root_minor = minor(st.st_dev);
 456
 457                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 458                  * /sys/block/loop* (for example) are symlinks to dirs,
 459                  * not real directories.
 460                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 461                  * but we can't enforce that on users)
 462                  */
 463                 if (access("/sys/class/block", F_OK) != 0) {
 464                         /* Scan obsolete /sys/block only if /sys/class/block
 465                          * doesn't exist. Otherwise we'll have dupes.
 466                          * Also, do not complain if it doesn't exist.
 467                          * Some people configure kernel to have no blockdevs.
 468                          */
 469                         recursive_action("/sys/block",
 470                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
 471                                 fileAction, dirAction, temp, 0);
 472                 }
 473                 recursive_action("/sys/class",
 474                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 475                         fileAction, dirAction, temp, 0);
 476         } else {
 477                 char *fw;
 478                 char *seq;
 479                 char *action;
 480                 char *env_path;
 481
 482                 /* Hotplug:
 483                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
 484                  * ACTION can be "add" or "remove"
 485                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 486                  */
 487                 action = getenv("ACTION");
 488                 env_path = getenv("DEVPATH");
 489                 subsystem = getenv("SUBSYSTEM");
 490                 if (!action || !env_path /*|| !subsystem*/)
 491                         bb_show_usage();
 492                 fw = getenv("FIRMWARE");
 493
 494                 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 495                  * If it does not match, earlier mdev is running
 496                  * in parallel, and we need to wait */
 497                 seq = getenv("SEQNUM");
 498                 if (seq) {
 499                         int timeout = 2000 / 32; /* 2000 msec */
 500                         do {
 501                                 int seqlen;
 502                                 char seqbuf[sizeof(int)*3 + 2];
 503
 504                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 505                                 if (seqlen < 0) {
 506                                         seq = NULL;
 507                                         break;
 508                                 }
 509                                 seqbuf[seqlen] = '\0';
 510                                 if (seqbuf[0] == '\n' /* seed file? */
 511                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 512                                 ) {
 513                                         break;
 514                                 }
 515                                 usleep(32*1000);
 516                         } while (--timeout);
 517                 }
 518
 519                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 520                 if (strcmp(action, "remove") == 0) {
 521                         /* Ignoring "remove firmware". It was reported
 522                          * to happen and to cause erroneous deletion
 523                          * of device nodes. */
 524                         if (!fw)
 525                                 make_device(temp, 1);
 526                 }
 527                 else if (strcmp(action, "add") == 0) {
 528                         make_device(temp, 0);
 529                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 530                                 if (fw)
 531                                         load_firmware(fw, temp);
 532                         }
 533                 }
 534
 535                 if (seq) {
 536                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 537                 }
 538         }
 539
 540         if (ENABLE_FEATURE_CLEAN_UP)
 541                 RELEASE_CONFIG_BUFFER(temp);
 542
 543         return EXIT_SUCCESS;
 544 }