util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  *
   4  * mdev - Mini udev for busybox
   5  *
   6  * Copyright 2005 Rob Landley <rob@landley.net>
   7  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   8  *
   9  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include "libbb.h"
  13 #include "xregex.h"
  14
  15 struct globals {
  16         int root_major, root_minor;
  17         char *subsystem;
  18 };
  19 #define G (*(struct globals*)&bb_common_bufsiz1)
  20 #define root_major (G.root_major)
  21 #define root_minor (G.root_minor)
  22 #define subsystem (G.subsystem)
  23
  24 /* Prevent infinite loops in /sys symlinks */
  25 #define MAX_SYSFS_DEPTH 3
  26
  27 /* We use additional 64+ bytes in make_device() */
  28 #define SCRATCH_SIZE 80
  29
  30 #if ENABLE_FEATURE_MDEV_RENAME
  31 /* Builds an alias path.
  32  * This function potentionally reallocates the alias parameter.
  33  */
  34 static char *build_alias(char *alias, const char *device_name)
  35 {
  36         char *dest;
  37
  38         /* ">bar/": rename to bar/device_name */
  39         /* ">bar[/]baz": rename to bar[/]baz */
  40         dest = strrchr(alias, '/');
  41         if (dest) { /* ">bar/[baz]" ? */
  42                 *dest = '\0'; /* mkdir bar */
  43                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
  44                 *dest = '/';
  45                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
  46                         dest = alias;
  47                         alias = concat_path_file(alias, device_name);
  48                         free(dest);
  49                 }
  50         }
  51
  52         return alias;
  53 }
  54 #endif
  55
  56 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  57 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  58 static void make_device(char *path, int delete)
  59 {
  60 #if ENABLE_FEATURE_MDEV_CONF
  61         parser_t *parser;
  62 #endif
  63         const char *device_name;
  64         int major, minor, type, len;
  65         int mode;
  66         char *dev_maj_min = path + strlen(path);
  67
  68         /* Force the configuration file settings exactly. */
  69         umask(0);
  70
  71         /* Try to read major/minor string.  Note that the kernel puts \n after
  72          * the data, so we don't need to worry about null terminating the string
  73          * because sscanf() will stop at the first nondigit, which \n is.
  74          * We also depend on path having writeable space after it.
  75          */
  76         major = -1;
  77         if (!delete) {
  78                 strcpy(dev_maj_min, "/dev");
  79                 len = open_read_close(path, dev_maj_min + 1, 64);
  80                 *dev_maj_min++ = '\0';
  81                 if (len < 1) {
  82                         if (!ENABLE_FEATURE_MDEV_EXEC)
  83                                 return;
  84                         /* no "dev" file, so just try to run script */
  85                         *dev_maj_min = '\0';
  86                 } else if (sscanf(dev_maj_min, "%u:%u", &major, &minor) != 2) {
  87                         major = -1;
  88                 }
  89         }
  90
  91         /* Determine device name, type, major and minor */
  92         device_name = bb_basename(path);
  93         /* http://kernel.org/doc/pending/hotplug.txt says that only
  94          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
  95          * But since 2.6.25 block devices are also in /sys/class/block.
  96          * We use strstr("/block/") to forestall future surprises. */
  97         type = S_IFCHR;
  98         if (strstr(path, "/block/"))
  99                 type = S_IFBLK;
 100
 101 #if ENABLE_FEATURE_MDEV_CONF
 102         parser = config_open2("/etc/mdev.conf", fopen_for_read);
 103
 104         /* If we have config file, look up user settings */
 105         while (1) {
 106                 regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 107                 int keep_matching;
 108                 char *val;
 109                 struct bb_uidgid_t ugid;
 110                 char *tokens[4];
 111 # if ENABLE_FEATURE_MDEV_EXEC
 112                 char *command = NULL;
 113 # endif
 114 # if ENABLE_FEATURE_MDEV_RENAME
 115                 char *alias = NULL;
 116                 char aliaslink = aliaslink; /* for compiler */
 117 # endif
 118                 /* Defaults in case we won't match any line */
 119                 ugid.uid = ugid.gid = 0;
 120                 keep_matching = 0;
 121                 mode = 0660;
 122
 123                 if (!config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)) {
 124                         /* End of file, create dev node with default params */
 125                         goto line_matches;
 126                 }
 127
 128                 val = tokens[0];
 129                 keep_matching = ('-' == val[0]);
 130                 val += keep_matching; /* swallow leading dash */
 131
 132                 /* Fields: regex uid:gid mode [alias] [cmd] */
 133
 134                 /* 1st field: @<numeric maj,min>... */
 135                 if (val[0] == '@') {
 136                         /* @major,minor[-last] */
 137                         /* (useful when name is ambiguous:
 138                          * "/sys/class/usb/lp0" and
 139                          * "/sys/class/printer/lp0") */
 140                         int cmaj, cmin0, cmin1, sc;
 141                         if (major < 0)
 142                                 continue; /* no dev, no match */
 143                         sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
 144                         if (sc < 1 || major != cmaj
 145                          || (sc == 2 && minor != cmin0)
 146                          || (sc == 3 && (minor < cmin0 || minor > cmin1))
 147                         ) {
 148                                 continue; /* this line doesn't match */
 149                         }
 150                 } else { /* ... or regex to match device name */
 151                         regex_t match;
 152                         int result;
 153                         const char *dev_name_or_subsystem = device_name;
 154                         if ('/' == val[0] && subsystem) {
 155                                 dev_name_or_subsystem = subsystem;
 156                                 val++;
 157                         }
 158
 159                         /* Is this it? */
 160                         xregcomp(&match, val, REG_EXTENDED);
 161                         result = regexec(&match, dev_name_or_subsystem, ARRAY_SIZE(off), off, 0);
 162                         regfree(&match);
 163
 164                         //bb_error_msg("matches:");
 165                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 166                         //      if (off[i].rm_so < 0) continue;
 167                         //      bb_error_msg("match %d: '%.*s'\n", i,
 168                         //              (int)(off[i].rm_eo - off[i].rm_so),
 169                         //              device_name + off[i].rm_so);
 170                         //}
 171
 172                         /* If not this device, skip rest of line */
 173                         /* (regexec returns whole pattern as "range" 0) */
 174                         if (result || off[0].rm_so
 175                          || ((int)off[0].rm_eo != (int)strlen(dev_name_or_subsystem))
 176                         ) {
 177                                 continue; /* this line doesn't match */
 178                         }
 179                 }
 180
 181                 /* This line matches: stop parsing the file after parsing
 182                  * the rest of fields unless keep_matching == 1 */
 183
 184                 /* 2nd field: uid:gid - device ownership */
 185                 parse_chown_usergroup_or_die(&ugid, 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 under /sys/class/ */
 356         if (1 == depth) {
 357                 subsystem = strrchr(fileName, '/');
 358                 if (subsystem)
 359                         subsystem++;
 360         }
 361
 362         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 363 }
 364
 365 /* For the full gory details, see linux/Documentation/firmware_class/README
 366  *
 367  * Firmware loading works like this:
 368  * - kernel sets FIRMWARE env var
 369  * - userspace checks /lib/firmware/$FIRMWARE
 370  * - userspace waits for /sys/$DEVPATH/loading to appear
 371  * - userspace writes "1" to /sys/$DEVPATH/loading
 372  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 373  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 374  * - kernel loads firmware into device
 375  */
 376 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 377 {
 378         int cnt;
 379         int firmware_fd, loading_fd, data_fd;
 380
 381         /* check for /lib/firmware/$FIRMWARE */
 382         xchdir("/lib/firmware");
 383         firmware_fd = xopen(firmware, O_RDONLY);
 384
 385         /* in case we goto out ... */
 386         data_fd = -1;
 387
 388         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 389         xchdir(sysfs_path);
 390         for (cnt = 0; cnt < 30; ++cnt) {
 391                 loading_fd = open("loading", O_WRONLY);
 392                 if (loading_fd != -1)
 393                         goto loading;
 394                 sleep(1);
 395         }
 396         goto out;
 397
 398  loading:
 399         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 400         if (full_write(loading_fd, "1", 1) != 1)
 401                 goto out;
 402
 403         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 404         data_fd = open("data", O_WRONLY);
 405         if (data_fd == -1)
 406                 goto out;
 407         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 408
 409         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 410         if (cnt > 0)
 411                 full_write(loading_fd, "0", 1);
 412         else
 413                 full_write(loading_fd, "-1", 2);
 414
 415  out:
 416         if (ENABLE_FEATURE_CLEAN_UP) {
 417                 close(firmware_fd);
 418                 close(loading_fd);
 419                 close(data_fd);
 420         }
 421 }
 422
 423 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 424 int mdev_main(int argc UNUSED_PARAM, char **argv)
 425 {
 426         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 427
 428         /* We can be called as hotplug helper */
 429         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 430 #if 1
 431         bb_sanitize_stdio();
 432 #else
 433         /* Debug code */
 434         /* Replace LOGFILE by other file or device name if you need */
 435 #define LOGFILE "/dev/console"
 436         /* Just making sure fd 0 is not closed,
 437          * we don't really intend to read from it */
 438         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 439         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 440         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 441 #endif
 442
 443         xchdir("/dev");
 444
 445         if (argv[1] && strcmp(argv[1], "-s") == 0) {
 446                 /* Scan:
 447                  * mdev -s
 448                  */
 449                 struct stat st;
 450
 451                 xstat("/", &st);
 452                 root_major = major(st.st_dev);
 453                 root_minor = minor(st.st_dev);
 454
 455                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 456                  * /sys/block/loop* (for example) are symlinks to dirs,
 457                  * not real directories.
 458                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 459                  * but we can't enforce that on users)
 460                  */
 461                 if (access("/sys/class/block", F_OK) != 0) {
 462                         /* Scan obsolete /sys/block only if /sys/class/block
 463                          * doesn't exist. Otherwise we'll have dupes.
 464                          * Also, do not complain if it doesn't exist.
 465                          * Some people configure kernel to have no blockdevs.
 466                          */
 467                         recursive_action("/sys/block",
 468                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
 469                                 fileAction, dirAction, temp, 0);
 470                 }
 471                 recursive_action("/sys/class",
 472                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 473                         fileAction, dirAction, temp, 0);
 474         } else {
 475                 char *fw;
 476                 char *seq;
 477                 char *action;
 478                 char *env_path;
 479
 480                 /* Hotplug:
 481                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
 482                  * ACTION can be "add" or "remove"
 483                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 484                  */
 485                 action = getenv("ACTION");
 486                 env_path = getenv("DEVPATH");
 487                 subsystem = getenv("SUBSYSTEM");
 488                 if (!action || !env_path /*|| !subsystem*/)
 489                         bb_show_usage();
 490                 fw = getenv("FIRMWARE");
 491
 492                 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 493                  * If it does not match, earlier mdev is running
 494                  * in parallel, and we need to wait */
 495                 seq = getenv("SEQNUM");
 496                 if (seq) {
 497                         int timeout = 2000 / 32; /* 2000 msec */
 498                         do {
 499                                 int seqlen;
 500                                 char seqbuf[sizeof(int)*3 + 2];
 501
 502                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 503                                 if (seqlen < 0) {
 504                                         seq = NULL;
 505                                         break;
 506                                 }
 507                                 seqbuf[seqlen] = '\0';
 508                                 if (seqbuf[0] == '\n' /* seed file? */
 509                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 510                                 ) {
 511                                         break;
 512                                 }
 513                                 usleep(32*1000);
 514                         } while (--timeout);
 515                 }
 516
 517                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 518                 if (strcmp(action, "remove") == 0) {
 519                         /* Ignoring "remove firmware". It was reported
 520                          * to happen and to cause erroneous deletion
 521                          * of device nodes. */
 522                         if (!fw)
 523                                 make_device(temp, 1);
 524                 }
 525                 else if (strcmp(action, "add") == 0) {
 526                         make_device(temp, 0);
 527                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 528                                 if (fw)
 529                                         load_firmware(fw, temp);
 530                         }
 531                 }
 532
 533                 if (seq) {
 534                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 535                 }
 536         }
 537
 538         if (ENABLE_FEATURE_CLEAN_UP)
 539                 RELEASE_CONFIG_BUFFER(temp);
 540
 541         return EXIT_SUCCESS;
 542 }