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