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 /* Builds an alias path.
  29  * This function potentionally reallocates the alias parameter.
  30  */
  31 static char *build_alias(char *alias, const char *device_name)
  32 {
  33         char *dest;
  34
  35         /* ">bar/": rename to bar/device_name */
  36         /* ">bar[/]baz": rename to bar[/]baz */
  37         dest = strrchr(alias, '/');
  38         if (dest) { /* ">bar/[baz]" ? */
  39                 *dest = '\0'; /* mkdir bar */
  40                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
  41                 *dest = '/';
  42                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
  43                         dest = alias;
  44                         alias = concat_path_file(alias, device_name);
  45                         free(dest);
  46                 }
  47         }
  48
  49         return alias;
  50 }
  51
  52 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  53 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  54 static void make_device(char *path, int delete)
  55 {
  56         const char *device_name;
  57         int major, minor, type, len;
  58         int mode = 0660;
  59         uid_t uid = 0;
  60         gid_t gid = 0;
  61         char *dev_maj_min = path + strlen(path);
  62         char *command = NULL;
  63         char *alias = NULL;
  64         char aliaslink = aliaslink; /* for compiler */
  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.  We
  72          * also depend on path having writeable space after it.
  73          */
  74         if (!delete) {
  75                 strcpy(dev_maj_min, "/dev");
  76                 len = open_read_close(path, dev_maj_min + 1, 64);
  77                 *dev_maj_min++ = '\0';
  78                 if (len < 1) {
  79                         if (!ENABLE_FEATURE_MDEV_EXEC)
  80                                 return;
  81                         /* no "dev" file, so just try to run script */
  82                         *dev_maj_min = '\0';
  83                 }
  84         }
  85
  86         /* Determine device name, type, major and minor */
  87         device_name = bb_basename(path);
  88         /* http://kernel.org/doc/pending/hotplug.txt says that only
  89          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
  90          * But since 2.6.25 block devices are also in /sys/class/block.
  91          * We use strstr("/block/") to forestall future surprises. */
  92         type = S_IFCHR;
  93         if (strstr(path, "/block/"))
  94                 type = S_IFBLK;
  95
  96         if (ENABLE_FEATURE_MDEV_CONF) {
  97                 parser_t *parser = config_open("/etc/mdev.conf");
  98                 char *tokens[5];
  99
 100                 /* If we have config file, look up user settings */
 101                 if (!parser)
 102                         goto end_parse;
 103
 104                 while (config_read(parser, tokens, 4, 3, " \t", '#') >= 0) {
 105                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 106                         char *val;
 107
 108                         /* Fields: regex uid:gid mode [alias] [cmd] */
 109
 110                         /* 1st field: regex to match this device */
 111                         {
 112                                 regex_t match;
 113                                 int result;
 114
 115                                 /* Is this it? */
 116                                 xregcomp(&match, tokens[0], REG_EXTENDED);
 117                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 118                                 regfree(&match);
 119
 120                                 //bb_error_msg("matches:");
 121                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 122                                 //      if (off[i].rm_so < 0) continue;
 123                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 124                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 125                                 //              device_name + off[i].rm_so);
 126                                 //}
 127
 128                                 /* If not this device, skip rest of line */
 129                                 /* (regexec returns whole pattern as "range" 0) */
 130                                 if (result || off[0].rm_so
 131                                  || ((int)off[0].rm_eo != (int)strlen(device_name))
 132                                 ) {
 133                                         continue;
 134                                 }
 135                         }
 136
 137                         /* This line matches: stop parsing the file
 138                          * after parsing the rest of fields */
 139
 140                         /* 2nd field: uid:gid - device ownership */
 141                         {
 142                                 struct passwd *pass;
 143                                 struct group *grp;
 144                                 char *str_uid = tokens[1];
 145                                 char *str_gid = strchrnul(str_uid, ':');
 146
 147                                 if (*str_gid)
 148                                         *str_gid++ = '\0';
 149                                 /* Parse UID */
 150                                 pass = getpwnam(str_uid);
 151                                 if (pass)
 152                                         uid = pass->pw_uid;
 153                                 else
 154                                         uid = strtoul(str_uid, NULL, 10);
 155                                 /* Parse GID */
 156                                 grp = getgrnam(str_gid);
 157                                 if (grp)
 158                                         gid = grp->gr_gid;
 159                                 else
 160                                         gid = strtoul(str_gid, NULL, 10);
 161                         }
 162
 163                         /* 3rd field: mode - device permissions */
 164                         mode = strtoul(tokens[2], NULL, 8);
 165
 166                         val = tokens[3];
 167                         /* 4th field (opt): >alias */
 168 #if ENABLE_FEATURE_MDEV_RENAME
 169                         if (!val)
 170                                 break;
 171                         aliaslink = *val;
 172                         if (aliaslink == '>' || aliaslink == '=') {
 173                                 char *s, *p;
 174                                 unsigned i, n;
 175                                 char *a = val;
 176                                 s = strchr(val, ' ');
 177                                 val = (s && s[1]) ? s+1 : NULL;
 178 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 179                                 /* substitute %1..9 with off[1..9], if any */
 180                                 n = 0;
 181                                 s = a;
 182                                 while (*s)
 183                                         if (*s++ == '%')
 184                                                 n++;
 185
 186                                 p = alias = xzalloc(strlen(a) + n * strlen(device_name));
 187                                 s = a + 1;
 188                                 while (*s) {
 189                                         *p = *s;
 190                                         if ('%' == *s) {
 191                                                 i = (s[1] - '0');
 192                                                 if (i <= 9 && off[i].rm_so >= 0) {
 193                                                         n = off[i].rm_eo - off[i].rm_so;
 194                                                         strncpy(p, device_name + off[i].rm_so, n);
 195                                                         p += n - 1;
 196                                                         s++;
 197                                                 }
 198                                         }
 199                                         p++;
 200                                         s++;
 201                                 }
 202 #else
 203                                 alias = xstrdup(a + 1);
 204 #endif
 205                         }
 206 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 207
 208                         /* The rest (opt): command to run */
 209                         if (!val)
 210                                 break;
 211                         if (ENABLE_FEATURE_MDEV_EXEC) {
 212                                 const char *s = "@$*";
 213                                 const char *s2 = strchr(s, *val);
 214
 215                                 if (!s2)
 216                                         bb_error_msg_and_die("bad line %u", parser->lineno);
 217
 218                                 /* Correlate the position in the "@$*" with the delete
 219                                  * step so that we get the proper behavior:
 220                                  * @cmd: run on create
 221                                  * $cmd: run on delete
 222                                  * *cmd: run on both
 223                                  */
 224                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 225                                         command = xstrdup(val + 1);
 226                                 }
 227                         }
 228                         /* end of field parsing */
 229                         break; /* we found matching line, stop */
 230                 } /* end of "while line is read from /etc/mdev.conf" */
 231
 232                 config_close(parser);
 233         }
 234  end_parse:
 235
 236         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 237
 238                 if (ENABLE_FEATURE_MDEV_RENAME)
 239                         unlink(device_name);
 240
 241                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 242                         bb_perror_msg_and_die("mknod %s", device_name);
 243
 244                 if (major == root_major && minor == root_minor)
 245                         symlink(device_name, "root");
 246
 247                 if (ENABLE_FEATURE_MDEV_CONF) {
 248                         chown(device_name, uid, gid);
 249
 250                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 251                                 alias = build_alias(alias, device_name);
 252
 253                                 /* move the device, and optionally
 254                                  * make a symlink to moved device node */
 255                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 256                                         symlink(alias, device_name);
 257
 258                                 free(alias);
 259                         }
 260                 }
 261         }
 262
 263         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 264                 /* setenv will leak memory, use putenv/unsetenv/free */
 265                 char *s = xasprintf("MDEV=%s", device_name);
 266                 putenv(s);
 267                 if (system(command) == -1)
 268                         bb_perror_msg_and_die("can't run '%s'", command);
 269                 s[4] = '\0';
 270                 unsetenv(s);
 271                 free(s);
 272                 free(command);
 273         }
 274
 275         if (delete) {
 276                 unlink(device_name);
 277                 /* At creation time, device might have been moved
 278                  * and a symlink might have been created. Undo that. */
 279                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 280                         alias = build_alias(alias, device_name);
 281                         unlink(alias);
 282                         free(alias);
 283                 }
 284         }
 285 }
 286
 287 /* File callback for /sys/ traversal */
 288 static int FAST_FUNC fileAction(const char *fileName,
 289                 struct stat *statbuf UNUSED_PARAM,
 290                 void *userData,
 291                 int depth UNUSED_PARAM)
 292 {
 293         size_t len = strlen(fileName) - 4; /* can't underflow */
 294         char *scratch = userData;
 295
 296         /* len check is for paranoid reasons */
 297         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 298                 return FALSE;
 299
 300         strcpy(scratch, fileName);
 301         scratch[len] = '\0';
 302         make_device(scratch, 0);
 303
 304         return TRUE;
 305 }
 306
 307 /* Directory callback for /sys/ traversal */
 308 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 309                 struct stat *statbuf UNUSED_PARAM,
 310                 void *userData UNUSED_PARAM,
 311                 int depth)
 312 {
 313         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 314 }
 315
 316 /* For the full gory details, see linux/Documentation/firmware_class/README
 317  *
 318  * Firmware loading works like this:
 319  * - kernel sets FIRMWARE env var
 320  * - userspace checks /lib/firmware/$FIRMWARE
 321  * - userspace waits for /sys/$DEVPATH/loading to appear
 322  * - userspace writes "1" to /sys/$DEVPATH/loading
 323  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 324  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 325  * - kernel loads firmware into device
 326  */
 327 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 328 {
 329         int cnt;
 330         int firmware_fd, loading_fd, data_fd;
 331
 332         /* check for /lib/firmware/$FIRMWARE */
 333         xchdir("/lib/firmware");
 334         firmware_fd = xopen(firmware, O_RDONLY);
 335
 336         /* in case we goto out ... */
 337         data_fd = -1;
 338
 339         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 340         xchdir(sysfs_path);
 341         for (cnt = 0; cnt < 30; ++cnt) {
 342                 loading_fd = open("loading", O_WRONLY);
 343                 if (loading_fd != -1)
 344                         goto loading;
 345                 sleep(1);
 346         }
 347         goto out;
 348
 349  loading:
 350         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 351         if (full_write(loading_fd, "1", 1) != 1)
 352                 goto out;
 353
 354         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 355         data_fd = open("data", O_WRONLY);
 356         if (data_fd == -1)
 357                 goto out;
 358         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 359
 360         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 361         if (cnt > 0)
 362                 full_write(loading_fd, "0", 1);
 363         else
 364                 full_write(loading_fd, "-1", 2);
 365
 366  out:
 367         if (ENABLE_FEATURE_CLEAN_UP) {
 368                 close(firmware_fd);
 369                 close(loading_fd);
 370                 close(data_fd);
 371         }
 372 }
 373
 374 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 375 int mdev_main(int argc UNUSED_PARAM, char **argv)
 376 {
 377         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 378
 379         /* We can be called as hotplug helper */
 380         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 381 #if 1
 382         bb_sanitize_stdio();
 383 #else
 384         /* Debug code */
 385         /* Replace LOGFILE by other file or device name if you need */
 386 #define LOGFILE "/dev/console"
 387         /* Just making sure fd 0 is not closed,
 388          * we don't really intend to read from it */
 389         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 390         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 391         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 392 #endif
 393
 394         xchdir("/dev");
 395
 396         if (argv[1] && !strcmp(argv[1], "-s")) {
 397                 /* Scan:
 398                  * mdev -s
 399                  */
 400                 struct stat st;
 401
 402                 xstat("/", &st);
 403                 root_major = major(st.st_dev);
 404                 root_minor = minor(st.st_dev);
 405
 406                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 407                  * /sys/block/loop* (for example) are symlinks to dirs,
 408                  * not real directories.
 409                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 410                  * but we can't enforce that on users) */
 411                 recursive_action("/sys/block",
 412                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 413                         fileAction, dirAction, temp, 0);
 414                 recursive_action("/sys/class",
 415                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 416                         fileAction, dirAction, temp, 0);
 417         } else {
 418                 char *seq;
 419                 char *action;
 420                 char *env_path;
 421                 char seqbuf[sizeof(int)*3 + 2];
 422                 int seqlen = seqlen; /* for compiler */
 423
 424                 /* Hotplug:
 425                  * env ACTION=... DEVPATH=... [SEQNUM=...] mdev
 426                  * ACTION can be "add" or "remove"
 427                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 428                  */
 429                 action = getenv("ACTION");
 430                 env_path = getenv("DEVPATH");
 431                 if (!action || !env_path)
 432                         bb_show_usage();
 433
 434                 seq = getenv("SEQNUM");
 435                 if (seq) {
 436                         int timeout = 2000 / 32;
 437                         do {
 438                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 439                                 if (seqlen < 0)
 440                                         break;
 441                                 seqbuf[seqlen] = '\0';
 442                                 if (seqbuf[0] == '\n' /* seed file? */
 443                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 444                                 ) {
 445                                         break;
 446                                 }
 447                                 usleep(32*1000);
 448                         } while (--timeout);
 449                 }
 450
 451                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 452                 if (!strcmp(action, "remove"))
 453                         make_device(temp, 1);
 454                 else if (!strcmp(action, "add")) {
 455                         make_device(temp, 0);
 456
 457                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 458                                 char *fw = getenv("FIRMWARE");
 459                                 if (fw)
 460                                         load_firmware(fw, temp);
 461                         }
 462                 }
 463
 464                 if (seq && seqlen >= 0) {
 465                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 466                 }
 467         }
 468
 469         if (ENABLE_FEATURE_CLEAN_UP)
 470                 RELEASE_CONFIG_BUFFER(temp);
 471
 472         return 0;
 473 }