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 };
  18 #define G (*(struct globals*)&bb_common_bufsiz1)
  19 #define root_major (G.root_major)
  20 #define root_minor (G.root_minor)
  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         const char *device_name;
  59         int major, minor, type, len;
  60         int mode = 0660;
  61 #if ENABLE_FEATURE_MDEV_CONF
  62         uid_t uid = 0;
  63         gid_t gid = 0;
  64         parser_t *parser;
  65         char *tokens[5];
  66 #endif
  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         char *dev_maj_min = path + strlen(path);
  75
  76         /* Force the configuration file settings exactly. */
  77         umask(0);
  78
  79         /* Try to read major/minor string.  Note that the kernel puts \n after
  80          * the data, so we don't need to worry about null terminating the string
  81          * because sscanf() will stop at the first nondigit, which \n is.  We
  82          * also depend on path having writeable space after it.
  83          */
  84         if (!delete) {
  85                 strcpy(dev_maj_min, "/dev");
  86                 len = open_read_close(path, dev_maj_min + 1, 64);
  87                 *dev_maj_min++ = '\0';
  88                 if (len < 1) {
  89                         if (!ENABLE_FEATURE_MDEV_EXEC)
  90                                 return;
  91                         /* no "dev" file, so just try to run script */
  92                         *dev_maj_min = '\0';
  93                 }
  94         }
  95
  96         /* Determine device name, type, major and minor */
  97         device_name = bb_basename(path);
  98         /* http://kernel.org/doc/pending/hotplug.txt says that only
  99          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 100          * But since 2.6.25 block devices are also in /sys/class/block.
 101          * We use strstr("/block/") to forestall future surprises. */
 102         type = S_IFCHR;
 103         if (strstr(path, "/block/"))
 104                 type = S_IFBLK;
 105
 106 #if ENABLE_FEATURE_MDEV_CONF
 107         parser = config_open2("/etc/mdev.conf", fopen_for_read);
 108
 109         /* If we have config file, look up user settings */
 110         if (!parser)
 111                 goto end_parse;
 112
 113         while (config_read(parser, tokens, 4, 3, "# \t", PARSE_LAST_IS_GREEDY)) {
 114                 regmatch_t off[1 + 9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 115                 char *val;
 116
 117                 /* Fields: regex uid:gid mode [alias] [cmd] */
 118
 119                 /* 1st field: regex to match this device */
 120                 {
 121                         regex_t match;
 122                         int result;
 123
 124                         /* Is this it? */
 125                         xregcomp(&match, tokens[0], REG_EXTENDED);
 126                         result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 127                         regfree(&match);
 128
 129                         //bb_error_msg("matches:");
 130                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 131                         //      if (off[i].rm_so < 0) continue;
 132                         //      bb_error_msg("match %d: '%.*s'\n", i,
 133                         //              (int)(off[i].rm_eo - off[i].rm_so),
 134                         //              device_name + off[i].rm_so);
 135                         //}
 136
 137                         /* If not this device, skip rest of line */
 138                         /* (regexec returns whole pattern as "range" 0) */
 139                         if (result || off[0].rm_so
 140                          || ((int)off[0].rm_eo != (int)strlen(device_name))
 141                         ) {
 142                                 continue;
 143                         }
 144                 }
 145
 146                 /* This line matches: stop parsing the file
 147                  * after parsing the rest of fields */
 148
 149                 /* 2nd field: uid:gid - device ownership */
 150                 {
 151                         struct passwd *pass;
 152                         struct group *grp;
 153                         char *str_uid = tokens[1];
 154                         char *str_gid = strchrnul(str_uid, ':');
 155
 156                         if (*str_gid)
 157                                 *str_gid++ = '\0';
 158                         /* Parse UID */
 159                         pass = getpwnam(str_uid);
 160                         if (pass)
 161                                 uid = pass->pw_uid;
 162                         else
 163                                 uid = strtoul(str_uid, NULL, 10);
 164                         /* Parse GID */
 165                         grp = getgrnam(str_gid);
 166                         if (grp)
 167                                 gid = grp->gr_gid;
 168                         else
 169                                 gid = strtoul(str_gid, NULL, 10);
 170                 }
 171
 172                 /* 3rd field: mode - device permissions */
 173                 mode = strtoul(tokens[2], NULL, 8);
 174
 175                 val = tokens[3];
 176                 /* 4th field (opt): >alias */
 177 #if ENABLE_FEATURE_MDEV_RENAME
 178                 if (!val)
 179                         break;
 180                 aliaslink = *val;
 181                 if (aliaslink == '>' || aliaslink == '=') {
 182                         char *s;
 183 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 184                         char *p;
 185                         unsigned i, n;
 186 #endif
 187                         char *a = val;
 188                         s = strchr(val, ' ');
 189                         val = (s && s[1]) ? s+1 : NULL;
 190 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 191                         /* substitute %1..9 with off[1..9], if any */
 192                         n = 0;
 193                         s = a;
 194                         while (*s)
 195                                 if (*s++ == '%')
 196                                         n++;
 197
 198                         p = alias = xzalloc(strlen(a) + n * strlen(device_name));
 199                         s = a + 1;
 200                         while (*s) {
 201                                 *p = *s;
 202                                 if ('%' == *s) {
 203                                         i = (s[1] - '0');
 204                                         if (i <= 9 && off[i].rm_so >= 0) {
 205                                                 n = off[i].rm_eo - off[i].rm_so;
 206                                                 strncpy(p, device_name + off[i].rm_so, n);
 207                                                 p += n - 1;
 208                                                 s++;
 209                                         }
 210                                 }
 211                                 p++;
 212                                 s++;
 213                         }
 214 #else
 215                         alias = xstrdup(a + 1);
 216 #endif
 217                 }
 218 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 219
 220 #if ENABLE_FEATURE_MDEV_EXEC
 221                 /* The rest (opt): command to run */
 222                 if (!val)
 223                         break;
 224                 {
 225                         const char *s = "@$*";
 226                         const char *s2 = strchr(s, *val);
 227
 228                         if (!s2)
 229                                 bb_error_msg_and_die("bad line %u", parser->lineno);
 230
 231                         /* Correlate the position in the "@$*" with the delete
 232                          * step so that we get the proper behavior:
 233                          * @cmd: run on create
 234                          * $cmd: run on delete
 235                          * *cmd: run on both
 236                          */
 237                         if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 238                                 command = xstrdup(val + 1);
 239                         }
 240                 }
 241 #endif
 242                 /* end of field parsing */
 243                 break; /* we found matching line, stop */
 244         } /* end of "while line is read from /etc/mdev.conf" */
 245
 246         config_close(parser);
 247  end_parse:
 248 #endif /* ENABLE_FEATURE_MDEV_CONF */
 249
 250         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 251
 252                 if (ENABLE_FEATURE_MDEV_RENAME)
 253                         unlink(device_name);
 254
 255                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 256                         bb_perror_msg_and_die("mknod %s", device_name);
 257
 258                 if (major == root_major && minor == root_minor)
 259                         symlink(device_name, "root");
 260
 261 #if ENABLE_FEATURE_MDEV_CONF
 262                 chown(device_name, uid, gid);
 263
 264 #if ENABLE_FEATURE_MDEV_RENAME
 265                 if (alias) {
 266                         alias = build_alias(alias, device_name);
 267
 268                         /* move the device, and optionally
 269                          * make a symlink to moved device node */
 270                         if (rename(device_name, alias) == 0 && aliaslink == '>')
 271                                 symlink(alias, device_name);
 272
 273                         free(alias);
 274                 }
 275 #endif
 276 #endif
 277         }
 278
 279 #if ENABLE_FEATURE_MDEV_EXEC
 280         if (command) {
 281                 /* setenv will leak memory, use putenv/unsetenv/free */
 282                 char *s = xasprintf("MDEV=%s", device_name);
 283                 putenv(s);
 284                 if (system(command) == -1)
 285                         bb_perror_msg_and_die("can't run '%s'", command);
 286                 s[4] = '\0';
 287                 unsetenv(s);
 288                 free(s);
 289                 free(command);
 290         }
 291 #endif
 292
 293         if (delete) {
 294                 unlink(device_name);
 295                 /* At creation time, device might have been moved
 296                  * and a symlink might have been created. Undo that. */
 297 #if ENABLE_FEATURE_MDEV_RENAME
 298                 if (alias) {
 299                         alias = build_alias(alias, device_name);
 300                         unlink(alias);
 301                         free(alias);
 302                 }
 303 #endif
 304         }
 305 }
 306
 307 /* File callback for /sys/ traversal */
 308 static int FAST_FUNC fileAction(const char *fileName,
 309                 struct stat *statbuf UNUSED_PARAM,
 310                 void *userData,
 311                 int depth UNUSED_PARAM)
 312 {
 313         size_t len = strlen(fileName) - 4; /* can't underflow */
 314         char *scratch = userData;
 315
 316         /* len check is for paranoid reasons */
 317         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 318                 return FALSE;
 319
 320         strcpy(scratch, fileName);
 321         scratch[len] = '\0';
 322         make_device(scratch, 0);
 323
 324         return TRUE;
 325 }
 326
 327 /* Directory callback for /sys/ traversal */
 328 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 329                 struct stat *statbuf UNUSED_PARAM,
 330                 void *userData UNUSED_PARAM,
 331                 int depth)
 332 {
 333         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 334 }
 335
 336 /* For the full gory details, see linux/Documentation/firmware_class/README
 337  *
 338  * Firmware loading works like this:
 339  * - kernel sets FIRMWARE env var
 340  * - userspace checks /lib/firmware/$FIRMWARE
 341  * - userspace waits for /sys/$DEVPATH/loading to appear
 342  * - userspace writes "1" to /sys/$DEVPATH/loading
 343  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 344  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 345  * - kernel loads firmware into device
 346  */
 347 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 348 {
 349         int cnt;
 350         int firmware_fd, loading_fd, data_fd;
 351
 352         /* check for /lib/firmware/$FIRMWARE */
 353         xchdir("/lib/firmware");
 354         firmware_fd = xopen(firmware, O_RDONLY);
 355
 356         /* in case we goto out ... */
 357         data_fd = -1;
 358
 359         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 360         xchdir(sysfs_path);
 361         for (cnt = 0; cnt < 30; ++cnt) {
 362                 loading_fd = open("loading", O_WRONLY);
 363                 if (loading_fd != -1)
 364                         goto loading;
 365                 sleep(1);
 366         }
 367         goto out;
 368
 369  loading:
 370         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 371         if (full_write(loading_fd, "1", 1) != 1)
 372                 goto out;
 373
 374         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 375         data_fd = open("data", O_WRONLY);
 376         if (data_fd == -1)
 377                 goto out;
 378         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 379
 380         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 381         if (cnt > 0)
 382                 full_write(loading_fd, "0", 1);
 383         else
 384                 full_write(loading_fd, "-1", 2);
 385
 386  out:
 387         if (ENABLE_FEATURE_CLEAN_UP) {
 388                 close(firmware_fd);
 389                 close(loading_fd);
 390                 close(data_fd);
 391         }
 392 }
 393
 394 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 395 int mdev_main(int argc UNUSED_PARAM, char **argv)
 396 {
 397         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 398
 399         /* We can be called as hotplug helper */
 400         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 401 #if 1
 402         bb_sanitize_stdio();
 403 #else
 404         /* Debug code */
 405         /* Replace LOGFILE by other file or device name if you need */
 406 #define LOGFILE "/dev/console"
 407         /* Just making sure fd 0 is not closed,
 408          * we don't really intend to read from it */
 409         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 410         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 411         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 412 #endif
 413
 414         xchdir("/dev");
 415
 416         if (argv[1] && !strcmp(argv[1], "-s")) {
 417                 /* Scan:
 418                  * mdev -s
 419                  */
 420                 struct stat st;
 421
 422                 xstat("/", &st);
 423                 root_major = major(st.st_dev);
 424                 root_minor = minor(st.st_dev);
 425
 426                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 427                  * /sys/block/loop* (for example) are symlinks to dirs,
 428                  * not real directories.
 429                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 430                  * but we can't enforce that on users) */
 431                 recursive_action("/sys/block",
 432                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 433                         fileAction, dirAction, temp, 0);
 434                 recursive_action("/sys/class",
 435                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 436                         fileAction, dirAction, temp, 0);
 437         } else {
 438                 char *seq;
 439                 char *action;
 440                 char *env_path;
 441                 char seqbuf[sizeof(int)*3 + 2];
 442                 int seqlen = seqlen; /* for compiler */
 443
 444                 /* Hotplug:
 445                  * env ACTION=... DEVPATH=... [SEQNUM=...] mdev
 446                  * ACTION can be "add" or "remove"
 447                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 448                  */
 449                 action = getenv("ACTION");
 450                 env_path = getenv("DEVPATH");
 451                 if (!action || !env_path)
 452                         bb_show_usage();
 453
 454                 seq = getenv("SEQNUM");
 455                 if (seq) {
 456                         int timeout = 2000 / 32;
 457                         do {
 458                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 459                                 if (seqlen < 0)
 460                                         break;
 461                                 seqbuf[seqlen] = '\0';
 462                                 if (seqbuf[0] == '\n' /* seed file? */
 463                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 464                                 ) {
 465                                         break;
 466                                 }
 467                                 usleep(32*1000);
 468                         } while (--timeout);
 469                 }
 470
 471                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 472                 if (!strcmp(action, "remove"))
 473                         make_device(temp, 1);
 474                 else if (!strcmp(action, "add")) {
 475                         make_device(temp, 0);
 476
 477                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 478                                 char *fw = getenv("FIRMWARE");
 479                                 if (fw)
 480                                         load_firmware(fw, temp);
 481                         }
 482                 }
 483
 484                 if (seq && seqlen >= 0) {
 485                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 486                 }
 487         }
 488
 489         if (ENABLE_FEATURE_CLEAN_UP)
 490                 RELEASE_CONFIG_BUFFER(temp);
 491
 492         return 0;
 493 }