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