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                 parse_chown_usergroup_or_die(&ugid, tokens[1]);
 185
 186                 /* 3rd field: mode - device permissions */
 187                 mode = strtoul(tokens[2], NULL, 8);
 188
 189                 val = tokens[3];
 190                 /* 4th field (opt): >|=alias */
 191 # if ENABLE_FEATURE_MDEV_RENAME
 192                 if (!val)
 193                         goto line_matches;
 194                 aliaslink = val[0];
 195                 if (aliaslink == '>' || aliaslink == '=') {
 196                         char *a, *s, *st;
 197 #  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 198                         char *p;
 199                         unsigned i, n;
 200 #  endif
 201                         a = val;
 202                         s = strchrnul(val, ' ');
 203                         st = strchrnul(val, '\t');
 204                         if (st < s)
 205                                 s = st;
 206                         val = (s[0] && s[1]) ? s+1 : NULL;
 207                         s[0] = '\0';
 208
 209 #  if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 210                         /* substitute %1..9 with off[1..9], if any */
 211                         n = 0;
 212                         s = a;
 213                         while (*s)
 214                                 if (*s++ == '%')
 215                                         n++;
 216
 217                         p = alias = xzalloc(strlen(a) + n * strlen(device_name));
 218                         s = a + 1;
 219                         while (*s) {
 220                                 *p = *s;
 221                                 if ('%' == *s) {
 222                                         i = (s[1] - '0');
 223                                         if (i <= 9 && off[i].rm_so >= 0) {
 224                                                 n = off[i].rm_eo - off[i].rm_so;
 225                                                 strncpy(p, device_name + off[i].rm_so, n);
 226                                                 p += n - 1;
 227                                                 s++;
 228                                         }
 229                                 }
 230                                 p++;
 231                                 s++;
 232                         }
 233 #  else
 234                         alias = xstrdup(a + 1);
 235 #  endif
 236                 }
 237 # endif /* ENABLE_FEATURE_MDEV_RENAME */
 238
 239 # if ENABLE_FEATURE_MDEV_EXEC
 240                 /* The rest (opt): @|$|*command */
 241                 if (!val)
 242                         goto line_matches;
 243                 {
 244                         const char *s = "@$*";
 245                         const char *s2 = strchr(s, val[0]);
 246
 247                         if (!s2)
 248                                 bb_error_msg_and_die("bad line %u", parser->lineno);
 249
 250                         /* Correlate the position in the "@$*" with the delete
 251                          * step so that we get the proper behavior:
 252                          * @cmd: run on create
 253                          * $cmd: run on delete
 254                          * *cmd: run on both
 255                          */
 256                         if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 257                                 command = xstrdup(val + 1);
 258                         }
 259                 }
 260 # endif
 261                 /* End of field parsing */
 262  line_matches:
 263 #endif /* ENABLE_FEATURE_MDEV_CONF */
 264
 265                 /* "Execute" the line we found */
 266
 267                 if (!delete && major >= 0) {
 268                         if (ENABLE_FEATURE_MDEV_RENAME)
 269                                 unlink(device_name);
 270                         if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 271                                 bb_perror_msg_and_die("mknod %s", device_name);
 272                         if (major == root_major && minor == root_minor)
 273                                 symlink(device_name, "root");
 274 #if ENABLE_FEATURE_MDEV_CONF
 275                         chown(device_name, ugid.uid, ugid.gid);
 276 # if ENABLE_FEATURE_MDEV_RENAME
 277                         if (alias) {
 278                                 alias = build_alias(alias, device_name);
 279                                 /* move the device, and optionally
 280                                  * make a symlink to moved device node */
 281                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 282                                         symlink(alias, device_name);
 283                                 free(alias);
 284                         }
 285 # endif
 286 #endif
 287                 }
 288 #if ENABLE_FEATURE_MDEV_EXEC
 289                 if (command) {
 290                         /* setenv will leak memory, use putenv/unsetenv/free */
 291                         char *s = xasprintf("%s=%s", "MDEV", device_name);
 292                         char *s1 = xasprintf("%s=%s", "SUBSYSTEM", subsystem);
 293                         putenv(s);
 294                         putenv(s1);
 295                         if (system(command) == -1)
 296                                 bb_perror_msg_and_die("can't run '%s'", command);
 297                         unsetenv("SUBSYSTEM");
 298                         free(s1);
 299                         unsetenv("MDEV");
 300                         free(s);
 301                         free(command);
 302                 }
 303 #endif
 304                 if (delete) {
 305                         unlink(device_name);
 306                         /* At creation time, device might have been moved
 307                          * and a symlink might have been created. Undo that. */
 308 #if ENABLE_FEATURE_MDEV_RENAME
 309                         if (alias) {
 310                                 alias = build_alias(alias, device_name);
 311                                 unlink(alias);
 312                                 free(alias);
 313                         }
 314 #endif
 315                 }
 316
 317 #if ENABLE_FEATURE_MDEV_CONF
 318                 /* We found matching line.
 319                  * Stop unless it was prefixed with '-' */
 320                 if (!keep_matching)
 321                         break;
 322         } /* end of "while line is read from /etc/mdev.conf" */
 323
 324         config_close(parser);
 325 #endif /* ENABLE_FEATURE_MDEV_CONF */
 326 }
 327
 328 /* File callback for /sys/ traversal */
 329 static int FAST_FUNC fileAction(const char *fileName,
 330                 struct stat *statbuf UNUSED_PARAM,
 331                 void *userData,
 332                 int depth UNUSED_PARAM)
 333 {
 334         size_t len = strlen(fileName) - 4; /* can't underflow */
 335         char *scratch = userData;
 336
 337         /* len check is for paranoid reasons */
 338         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 339                 return FALSE;
 340
 341         strcpy(scratch, fileName);
 342         scratch[len] = '\0';
 343         make_device(scratch, 0);
 344
 345         return TRUE;
 346 }
 347
 348 /* Directory callback for /sys/ traversal */
 349 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 350                 struct stat *statbuf UNUSED_PARAM,
 351                 void *userData UNUSED_PARAM,
 352                 int depth)
 353 {
 354         /* Extract device subsystem -- the name of the directory
 355          * under /sys/class/ */
 356         if (1 == depth) {
 357                 free(subsystem);
 358                 subsystem = strrchr(fileName, '/');
 359                 if (subsystem)
 360                         subsystem = xstrdup(subsystem + 1);
 361         }
 362
 363         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 364 }
 365
 366 /* For the full gory details, see linux/Documentation/firmware_class/README
 367  *
 368  * Firmware loading works like this:
 369  * - kernel sets FIRMWARE env var
 370  * - userspace checks /lib/firmware/$FIRMWARE
 371  * - userspace waits for /sys/$DEVPATH/loading to appear
 372  * - userspace writes "1" to /sys/$DEVPATH/loading
 373  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 374  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 375  * - kernel loads firmware into device
 376  */
 377 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 378 {
 379         int cnt;
 380         int firmware_fd, loading_fd, data_fd;
 381
 382         /* check for /lib/firmware/$FIRMWARE */
 383         xchdir("/lib/firmware");
 384         firmware_fd = xopen(firmware, O_RDONLY);
 385
 386         /* in case we goto out ... */
 387         data_fd = -1;
 388
 389         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 390         xchdir(sysfs_path);
 391         for (cnt = 0; cnt < 30; ++cnt) {
 392                 loading_fd = open("loading", O_WRONLY);
 393                 if (loading_fd != -1)
 394                         goto loading;
 395                 sleep(1);
 396         }
 397         goto out;
 398
 399  loading:
 400         /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 401         if (full_write(loading_fd, "1", 1) != 1)
 402                 goto out;
 403
 404         /* load firmware into /sys/$DEVPATH/data */
 405         data_fd = open("data", O_WRONLY);
 406         if (data_fd == -1)
 407                 goto out;
 408         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 409
 410         /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
 411         if (cnt > 0)
 412                 full_write(loading_fd, "0", 1);
 413         else
 414                 full_write(loading_fd, "-1", 2);
 415
 416  out:
 417         if (ENABLE_FEATURE_CLEAN_UP) {
 418                 close(firmware_fd);
 419                 close(loading_fd);
 420                 close(data_fd);
 421         }
 422 }
 423
 424 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 425 int mdev_main(int argc UNUSED_PARAM, char **argv)
 426 {
 427         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 428
 429         /* We can be called as hotplug helper */
 430         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 431 #if 1
 432         bb_sanitize_stdio();
 433 #else
 434         /* Debug code */
 435         /* Replace LOGFILE by other file or device name if you need */
 436 #define LOGFILE "/dev/console"
 437         /* Just making sure fd 0 is not closed,
 438          * we don't really intend to read from it */
 439         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 440         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 441         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 442 #endif
 443
 444         xchdir("/dev");
 445
 446         if (argv[1] && strcmp(argv[1], "-s") == 0) {
 447                 /* Scan:
 448                  * mdev -s
 449                  */
 450                 struct stat st;
 451
 452                 xstat("/", &st);
 453                 root_major = major(st.st_dev);
 454                 root_minor = minor(st.st_dev);
 455
 456                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 457                  * /sys/block/loop* (for example) are symlinks to dirs,
 458                  * not real directories.
 459                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 460                  * but we can't enforce that on users)
 461                  */
 462                 if (access("/sys/class/block", F_OK) != 0) {
 463                         /* Scan obsolete /sys/block only if /sys/class/block
 464                          * doesn't exist. Otherwise we'll have dupes.
 465                          * Also, do not complain if it doesn't exist.
 466                          * Some people configure kernel to have no blockdevs.
 467                          */
 468                         recursive_action("/sys/block",
 469                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
 470                                 fileAction, dirAction, temp, 0);
 471                 }
 472                 recursive_action("/sys/class",
 473                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 474                         fileAction, dirAction, temp, 0);
 475         } else {
 476                 char *fw;
 477                 char *seq;
 478                 char *action;
 479                 char *env_path;
 480
 481                 /* Hotplug:
 482                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
 483                  * ACTION can be "add" or "remove"
 484                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 485                  */
 486                 action = getenv("ACTION");
 487                 env_path = getenv("DEVPATH");
 488                 subsystem = getenv("SUBSYSTEM");
 489                 if (!action || !env_path /*|| !subsystem*/)
 490                         bb_show_usage();
 491                 fw = getenv("FIRMWARE");
 492
 493                 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 494                  * If it does not match, earlier mdev is running
 495                  * in parallel, and we need to wait */
 496                 seq = getenv("SEQNUM");
 497                 if (seq) {
 498                         int timeout = 2000 / 32; /* 2000 msec */
 499                         do {
 500                                 int seqlen;
 501                                 char seqbuf[sizeof(int)*3 + 2];
 502
 503                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 504                                 if (seqlen < 0) {
 505                                         seq = NULL;
 506                                         break;
 507                                 }
 508                                 seqbuf[seqlen] = '\0';
 509                                 if (seqbuf[0] == '\n' /* seed file? */
 510                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 511                                 ) {
 512                                         break;
 513                                 }
 514                                 usleep(32*1000);
 515                         } while (--timeout);
 516                 }
 517
 518                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 519                 if (strcmp(action, "remove") == 0) {
 520                         /* Ignoring "remove firmware". It was reported
 521                          * to happen and to cause erroneous deletion
 522                          * of device nodes. */
 523                         if (!fw)
 524                                 make_device(temp, 1);
 525                 }
 526                 else if (strcmp(action, "add") == 0) {
 527                         make_device(temp, 0);
 528                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 529                                 if (fw)
 530                                         load_firmware(fw, temp);
 531                         }
 532                 }
 533
 534                 if (seq) {
 535                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 536                 }
 537         }
 538
 539         if (ENABLE_FEATURE_CLEAN_UP)
 540                 RELEASE_CONFIG_BUFFER(temp);
 541
 542         return EXIT_SUCCESS;
 543 }