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 static char *next_field(char *s)
  29 {
  30         char *end = skip_non_whitespace(s);
  31         s = skip_whitespace(end);
  32         *end = '\0';
  33         if (*s == '\0')
  34                 s = NULL;
  35         return s;
  36 }
  37
  38 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  39 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  40 static void make_device(char *path, int delete)
  41 {
  42         const char *device_name;
  43         int major, minor, type, len;
  44         int mode = 0660;
  45         uid_t uid = 0;
  46         gid_t gid = 0;
  47         char *dev_maj_min = path + strlen(path);
  48         char *command = NULL;
  49         char *alias = NULL;
  50         char aliaslink = aliaslink; /* for compiler */
  51
  52         /* Force the configuration file settings exactly. */
  53         umask(0);
  54
  55         /* Try to read major/minor string.  Note that the kernel puts \n after
  56          * the data, so we don't need to worry about null terminating the string
  57          * because sscanf() will stop at the first nondigit, which \n is.  We
  58          * also depend on path having writeable space after it.
  59          */
  60         if (!delete) {
  61                 strcpy(dev_maj_min, "/dev");
  62                 len = open_read_close(path, dev_maj_min + 1, 64);
  63                 *dev_maj_min++ = '\0';
  64                 if (len < 1) {
  65                         if (!ENABLE_FEATURE_MDEV_EXEC)
  66                                 return;
  67                         /* no "dev" file, so just try to run script */
  68                         *dev_maj_min = '\0';
  69                 }
  70         }
  71
  72         /* Determine device name, type, major and minor */
  73         device_name = bb_basename(path);
  74         /* http://kernel.org/doc/pending/hotplug.txt says that only
  75          * "/sys/block/..." is for block devices. "/sys/bus" etc is not!
  76          * Since kernel 2.6.25 block devices are also in /sys/class/block. */
  77         /* TODO: would it be acceptable to just use strstr(path, "/block/")? */
  78         if (strncmp(&path[5], "class/block/"+6, 6) != 0
  79          && strncmp(&path[5], "class/block/", 12) != 0)
  80                 type = S_IFCHR;
  81         else
  82                 type = S_IFBLK;
  83
  84         if (ENABLE_FEATURE_MDEV_CONF) {
  85                 FILE *fp;
  86                 char *line, *val, *next;
  87                 unsigned lineno = 0;
  88
  89                 /* If we have config file, look up user settings */
  90                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  91                 if (!fp)
  92                         goto end_parse;
  93
  94                 while ((line = xmalloc_fgetline(fp)) != NULL) {
  95                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
  96
  97                         ++lineno;
  98                         trim(line);
  99                         if (!line[0])
 100                                 goto next_line;
 101
 102                         /* Fields: regex uid:gid mode [alias] [cmd] */
 103
 104                         /* 1st field: regex to match this device */
 105                         next = next_field(line);
 106                         {
 107                                 regex_t match;
 108                                 int result;
 109
 110                                 /* Is this it? */
 111                                 xregcomp(&match, line, REG_EXTENDED);
 112                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 113                                 regfree(&match);
 114
 115                                 //bb_error_msg("matches:");
 116                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 117                                 //      if (off[i].rm_so < 0) continue;
 118                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 119                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 120                                 //              device_name + off[i].rm_so);
 121                                 //}
 122
 123                                 /* If not this device, skip rest of line */
 124                                 /* (regexec returns whole pattern as "range" 0) */
 125                                 if (result || off[0].rm_so
 126                                  || ((int)off[0].rm_eo != (int)strlen(device_name))
 127                                 ) {
 128                                         goto next_line;
 129                                 }
 130                         }
 131
 132                         /* This line matches: stop parsing the file
 133                          * after parsing the rest of fields */
 134
 135                         /* 2nd field: uid:gid - device ownership */
 136                         if (!next) /* field must exist */
 137                                 bb_error_msg_and_die("bad line %u", lineno);
 138                         val = next;
 139                         next = next_field(val);
 140                         {
 141                                 struct passwd *pass;
 142                                 struct group *grp;
 143                                 char *str_uid = val;
 144                                 char *str_gid = strchrnul(val, ':');
 145
 146                                 if (*str_gid)
 147                                         *str_gid++ = '\0';
 148                                 /* Parse UID */
 149                                 pass = getpwnam(str_uid);
 150                                 if (pass)
 151                                         uid = pass->pw_uid;
 152                                 else
 153                                         uid = strtoul(str_uid, NULL, 10);
 154                                 /* Parse GID */
 155                                 grp = getgrnam(str_gid);
 156                                 if (grp)
 157                                         gid = grp->gr_gid;
 158                                 else
 159                                         gid = strtoul(str_gid, NULL, 10);
 160                         }
 161
 162                         /* 3rd field: mode - device permissions */
 163                         if (!next) /* field must exist */
 164                                 bb_error_msg_and_die("bad line %u", lineno);
 165                         val = next;
 166                         next = next_field(val);
 167                         mode = strtoul(val, NULL, 8);
 168
 169                         /* 4th field (opt): >alias */
 170 #if ENABLE_FEATURE_MDEV_RENAME
 171                         if (!next)
 172                                 break;
 173                         if (*next == '>' || *next == '=') {
 174 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 175                                 char *s, *p;
 176                                 unsigned i, n;
 177
 178                                 aliaslink = *next;
 179                                 val = next;
 180                                 next = next_field(val);
 181                                 /* substitute %1..9 with off[1..9], if any */
 182                                 n = 0;
 183                                 s = val;
 184                                 while (*s)
 185                                         if (*s++ == '%')
 186                                                 n++;
 187
 188                                 p = alias = xzalloc(strlen(val) + n * strlen(device_name));
 189                                 s = val + 1;
 190                                 while (*s) {
 191                                         *p = *s;
 192                                         if ('%' == *s) {
 193                                                 i = (s[1] - '0');
 194                                                 if (i <= 9 && off[i].rm_so >= 0) {
 195                                                         n = off[i].rm_eo - off[i].rm_so;
 196                                                         strncpy(p, device_name + off[i].rm_so, n);
 197                                                         p += n - 1;
 198                                                         s++;
 199                                                 }
 200                                         }
 201                                         p++;
 202                                         s++;
 203                                 }
 204 #else
 205                                 aliaslink = *next;
 206                                 val = next;
 207                                 next = next_field(val);
 208                                 alias = xstrdup(val + 1);
 209 #endif
 210                         }
 211 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 212
 213                         /* The rest (opt): command to run */
 214                         if (!next)
 215                                 break;
 216                         val = next;
 217                         if (ENABLE_FEATURE_MDEV_EXEC) {
 218                                 const char *s = "@$*";
 219                                 const char *s2 = strchr(s, *val);
 220
 221                                 if (!s2)
 222                                         bb_error_msg_and_die("bad line %u", lineno);
 223
 224                                 /* Correlate the position in the "@$*" with the delete
 225                                  * step so that we get the proper behavior:
 226                                  * @cmd: run on create
 227                                  * $cmd: run on delete
 228                                  * *cmd: run on both
 229                                  */
 230                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 231                                         command = xstrdup(val + 1);
 232                                 }
 233                         }
 234                         /* end of field parsing */
 235                         break; /* we found matching line, stop */
 236  next_line:
 237                         free(line);
 238                 } /* end of "while line is read from /etc/mdev.conf" */
 239
 240                 free(line); /* in case we used "break" to get here */
 241                 fclose(fp);
 242         }
 243  end_parse:
 244
 245         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 246
 247                 if (ENABLE_FEATURE_MDEV_RENAME)
 248                         unlink(device_name);
 249
 250                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 251                         bb_perror_msg_and_die("mknod %s", device_name);
 252
 253                 if (major == root_major && minor == root_minor)
 254                         symlink(device_name, "root");
 255
 256                 if (ENABLE_FEATURE_MDEV_CONF) {
 257                         chown(device_name, uid, gid);
 258
 259                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 260                                 char *dest;
 261
 262                                 /* ">bar/": rename to bar/device_name */
 263                                 /* ">bar[/]baz": rename to bar[/]baz */
 264                                 dest = strrchr(alias, '/');
 265                                 if (dest) { /* ">bar/[baz]" ? */
 266                                         *dest = '\0'; /* mkdir bar */
 267                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 268                                         *dest = '/';
 269                                         if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 270                                                 dest = alias;
 271                                                 alias = concat_path_file(alias, device_name);
 272                                                 free(dest);
 273                                         }
 274                                 }
 275
 276                                 /* move the device, and optionally
 277                                  * make a symlink to moved device node */
 278                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 279                                         symlink(alias, device_name);
 280
 281                                 free(alias);
 282                         }
 283                 }
 284         }
 285
 286         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 287                 /* setenv will leak memory, use putenv/unsetenv/free */
 288                 char *s = xasprintf("MDEV=%s", device_name);
 289                 putenv(s);
 290                 if (system(command) == -1)
 291                         bb_perror_msg_and_die("can't run '%s'", command);
 292                 s[4] = '\0';
 293                 unsetenv(s);
 294                 free(s);
 295                 free(command);
 296         }
 297
 298         if (delete)
 299                 unlink(device_name);
 300 }
 301
 302 /* File callback for /sys/ traversal */
 303 static int FAST_FUNC fileAction(const char *fileName,
 304                 struct stat *statbuf UNUSED_PARAM,
 305                 void *userData,
 306                 int depth UNUSED_PARAM)
 307 {
 308         size_t len = strlen(fileName) - 4; /* can't underflow */
 309         char *scratch = userData;
 310
 311         /* len check is for paranoid reasons */
 312         if (strcmp(fileName + len, "/dev") || len >= PATH_MAX)
 313                 return FALSE;
 314
 315         strcpy(scratch, fileName);
 316         scratch[len] = '\0';
 317         make_device(scratch, 0);
 318
 319         return TRUE;
 320 }
 321
 322 /* Directory callback for /sys/ traversal */
 323 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 324                 struct stat *statbuf UNUSED_PARAM,
 325                 void *userData UNUSED_PARAM,
 326                 int depth)
 327 {
 328         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 329 }
 330
 331 /* For the full gory details, see linux/Documentation/firmware_class/README
 332  *
 333  * Firmware loading works like this:
 334  * - kernel sets FIRMWARE env var
 335  * - userspace checks /lib/firmware/$FIRMWARE
 336  * - userspace waits for /sys/$DEVPATH/loading to appear
 337  * - userspace writes "1" to /sys/$DEVPATH/loading
 338  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 339  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 340  * - kernel loads firmware into device
 341  */
 342 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 343 {
 344         int cnt;
 345         int firmware_fd, loading_fd, data_fd;
 346
 347         /* check for /lib/firmware/$FIRMWARE */
 348         xchdir("/lib/firmware");
 349         firmware_fd = xopen(firmware, O_RDONLY);
 350
 351         /* in case we goto out ... */
 352         data_fd = -1;
 353
 354         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 355         xchdir(sysfs_path);
 356         for (cnt = 0; cnt < 30; ++cnt) {
 357                 loading_fd = open("loading", O_WRONLY);
 358                 if (loading_fd != -1)
 359                         goto loading;
 360                 sleep(1);
 361         }
 362         goto out;
 363
 364  loading:
 365         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 366         if (full_write(loading_fd, "1", 1) != 1)
 367                 goto out;
 368
 369         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 370         data_fd = open("data", O_WRONLY);
 371         if (data_fd == -1)
 372                 goto out;
 373         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 374
 375         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 376         if (cnt > 0)
 377                 full_write(loading_fd, "0", 1);
 378         else
 379                 full_write(loading_fd, "-1", 2);
 380
 381  out:
 382         if (ENABLE_FEATURE_CLEAN_UP) {
 383                 close(firmware_fd);
 384                 close(loading_fd);
 385                 close(data_fd);
 386         }
 387 }
 388
 389 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 390 int mdev_main(int argc, char **argv)
 391 {
 392         char *action;
 393         char *env_path;
 394         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 395
 396         /* We can be called as hotplug helper */
 397         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 398 #if 1
 399         bb_sanitize_stdio();
 400 #else
 401         /* Debug code */
 402         /* Replace LOGFILE by other file or device name if you need */
 403 #define LOGFILE "/dev/console"
 404         /* Just making sure fd 0 is not closed,
 405          * we don't really intend to read from it */
 406         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 407         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 408         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 409 #endif
 410
 411         xchdir("/dev");
 412
 413         if (argc == 2 && !strcmp(argv[1], "-s")) {
 414                 /* Scan:
 415                  * mdev -s
 416                  */
 417                 struct stat st;
 418
 419                 xstat("/", &st);
 420                 root_major = major(st.st_dev);
 421                 root_minor = minor(st.st_dev);
 422
 423                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 424                  * /sys/block/loop* (for example) are symlinks to dirs,
 425                  * not real directories.
 426                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 427                  * but we can't enforce that on users) */
 428                 recursive_action("/sys/block",
 429                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 430                         fileAction, dirAction, temp, 0);
 431                 recursive_action("/sys/class",
 432                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 433                         fileAction, dirAction, temp, 0);
 434         } else {
 435                 /* Hotplug:
 436                  * env ACTION=... DEVPATH=... mdev
 437                  * ACTION can be "add" or "remove"
 438                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 439                  */
 440                 action = getenv("ACTION");
 441                 env_path = getenv("DEVPATH");
 442                 if (!action || !env_path)
 443                         bb_show_usage();
 444
 445                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 446                 if (!strcmp(action, "remove"))
 447                         make_device(temp, 1);
 448                 else if (!strcmp(action, "add")) {
 449                         make_device(temp, 0);
 450
 451                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 452                                 char *fw = getenv("FIRMWARE");
 453                                 if (fw)
 454                                         load_firmware(fw, temp);
 455                         }
 456                 }
 457         }
 458
 459         if (ENABLE_FEATURE_CLEAN_UP)
 460                 RELEASE_CONFIG_BUFFER(temp);
 461
 462         return 0;
 463 }