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 /* Builds an alias path.
  39  * This function potentionally reallocates the alias parameter.
  40  */
  41 static char *build_alias(char *alias, const char *device_name)
  42 {
  43         char *dest;
  44
  45         /* ">bar/": rename to bar/device_name */
  46         /* ">bar[/]baz": rename to bar[/]baz */
  47         dest = strrchr(alias, '/');
  48         if (dest) { /* ">bar/[baz]" ? */
  49                 *dest = '\0'; /* mkdir bar */
  50                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
  51                 *dest = '/';
  52                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
  53                         dest = alias;
  54                         alias = concat_path_file(alias, device_name);
  55                         free(dest);
  56                 }
  57         }
  58
  59         return alias;
  60 }
  61
  62 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  63 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  64 static void make_device(char *path, int delete)
  65 {
  66         const char *device_name;
  67         int major, minor, type, len;
  68         int mode = 0660;
  69         uid_t uid = 0;
  70         gid_t gid = 0;
  71         char *dev_maj_min = path + strlen(path);
  72         char *command = NULL;
  73         char *alias = NULL;
  74         char aliaslink = aliaslink; /* for compiler */
  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                 FILE *fp;
 108                 char *line, *val, *next;
 109                 unsigned lineno = 0;
 110
 111                 /* If we have config file, look up user settings */
 112                 fp = fopen_or_warn("/etc/mdev.conf", "r");
 113                 if (!fp)
 114                         goto end_parse;
 115
 116                 while ((line = xmalloc_fgetline(fp)) != NULL) {
 117                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 118
 119                         ++lineno;
 120                         trim(line);
 121                         if (!line[0])
 122                                 goto next_line;
 123
 124                         /* Fields: regex uid:gid mode [alias] [cmd] */
 125
 126                         /* 1st field: regex to match this device */
 127                         next = next_field(line);
 128                         {
 129                                 regex_t match;
 130                                 int result;
 131
 132                                 /* Is this it? */
 133                                 xregcomp(&match, line, REG_EXTENDED);
 134                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 135                                 regfree(&match);
 136
 137                                 //bb_error_msg("matches:");
 138                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 139                                 //      if (off[i].rm_so < 0) continue;
 140                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 141                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 142                                 //              device_name + off[i].rm_so);
 143                                 //}
 144
 145                                 /* If not this device, skip rest of line */
 146                                 /* (regexec returns whole pattern as "range" 0) */
 147                                 if (result || off[0].rm_so
 148                                  || ((int)off[0].rm_eo != (int)strlen(device_name))
 149                                 ) {
 150                                         goto next_line;
 151                                 }
 152                         }
 153
 154                         /* This line matches: stop parsing the file
 155                          * after parsing the rest of fields */
 156
 157                         /* 2nd field: uid:gid - device ownership */
 158                         if (!next) /* field must exist */
 159                                 bb_error_msg_and_die("bad line %u", lineno);
 160                         val = next;
 161                         next = next_field(val);
 162                         {
 163                                 struct passwd *pass;
 164                                 struct group *grp;
 165                                 char *str_uid = val;
 166                                 char *str_gid = strchrnul(val, ':');
 167
 168                                 if (*str_gid)
 169                                         *str_gid++ = '\0';
 170                                 /* Parse UID */
 171                                 pass = getpwnam(str_uid);
 172                                 if (pass)
 173                                         uid = pass->pw_uid;
 174                                 else
 175                                         uid = strtoul(str_uid, NULL, 10);
 176                                 /* Parse GID */
 177                                 grp = getgrnam(str_gid);
 178                                 if (grp)
 179                                         gid = grp->gr_gid;
 180                                 else
 181                                         gid = strtoul(str_gid, NULL, 10);
 182                         }
 183
 184                         /* 3rd field: mode - device permissions */
 185                         if (!next) /* field must exist */
 186                                 bb_error_msg_and_die("bad line %u", lineno);
 187                         val = next;
 188                         next = next_field(val);
 189                         mode = strtoul(val, NULL, 8);
 190
 191                         /* 4th field (opt): >alias */
 192 #if ENABLE_FEATURE_MDEV_RENAME
 193                         if (!next)
 194                                 break;
 195                         if (*next == '>' || *next == '=') {
 196 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 197                                 char *s, *p;
 198                                 unsigned i, n;
 199
 200                                 aliaslink = *next;
 201                                 val = next;
 202                                 next = next_field(val);
 203                                 /* substitute %1..9 with off[1..9], if any */
 204                                 n = 0;
 205                                 s = val;
 206                                 while (*s)
 207                                         if (*s++ == '%')
 208                                                 n++;
 209
 210                                 p = alias = xzalloc(strlen(val) + n * strlen(device_name));
 211                                 s = val + 1;
 212                                 while (*s) {
 213                                         *p = *s;
 214                                         if ('%' == *s) {
 215                                                 i = (s[1] - '0');
 216                                                 if (i <= 9 && off[i].rm_so >= 0) {
 217                                                         n = off[i].rm_eo - off[i].rm_so;
 218                                                         strncpy(p, device_name + off[i].rm_so, n);
 219                                                         p += n - 1;
 220                                                         s++;
 221                                                 }
 222                                         }
 223                                         p++;
 224                                         s++;
 225                                 }
 226 #else
 227                                 aliaslink = *next;
 228                                 val = next;
 229                                 next = next_field(val);
 230                                 alias = xstrdup(val + 1);
 231 #endif
 232                         }
 233 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 234
 235                         /* The rest (opt): command to run */
 236                         if (!next)
 237                                 break;
 238                         val = next;
 239                         if (ENABLE_FEATURE_MDEV_EXEC) {
 240                                 const char *s = "@$*";
 241                                 const char *s2 = strchr(s, *val);
 242
 243                                 if (!s2)
 244                                         bb_error_msg_and_die("bad line %u", lineno);
 245
 246                                 /* Correlate the position in the "@$*" with the delete
 247                                  * step so that we get the proper behavior:
 248                                  * @cmd: run on create
 249                                  * $cmd: run on delete
 250                                  * *cmd: run on both
 251                                  */
 252                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 253                                         command = xstrdup(val + 1);
 254                                 }
 255                         }
 256                         /* end of field parsing */
 257                         break; /* we found matching line, stop */
 258  next_line:
 259                         free(line);
 260                 } /* end of "while line is read from /etc/mdev.conf" */
 261
 262                 free(line); /* in case we used "break" to get here */
 263                 fclose(fp);
 264         }
 265  end_parse:
 266
 267         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 268
 269                 if (ENABLE_FEATURE_MDEV_RENAME)
 270                         unlink(device_name);
 271
 272                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 273                         bb_perror_msg_and_die("mknod %s", device_name);
 274
 275                 if (major == root_major && minor == root_minor)
 276                         symlink(device_name, "root");
 277
 278                 if (ENABLE_FEATURE_MDEV_CONF) {
 279                         chown(device_name, uid, gid);
 280
 281                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 282                                 alias = build_alias(alias, device_name);
 283
 284                                 /* move the device, and optionally
 285                                  * make a symlink to moved device node */
 286                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 287                                         symlink(alias, device_name);
 288
 289                                 free(alias);
 290                         }
 291                 }
 292         }
 293
 294         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 295                 /* setenv will leak memory, use putenv/unsetenv/free */
 296                 char *s = xasprintf("MDEV=%s", device_name);
 297                 putenv(s);
 298                 if (system(command) == -1)
 299                         bb_perror_msg_and_die("can't run '%s'", command);
 300                 s[4] = '\0';
 301                 unsetenv(s);
 302                 free(s);
 303                 free(command);
 304         }
 305
 306         if (delete) {
 307                 unlink(device_name);
 308                 /* At creation time, device might have been moved
 309                  * and a symlink might have been created. Undo that. */
 310                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 311                         alias = build_alias(alias, device_name);
 312                         unlink(alias);
 313                         free(alias);
 314                 }
 315         }
 316 }
 317
 318 /* File callback for /sys/ traversal */
 319 static int FAST_FUNC fileAction(const char *fileName,
 320                 struct stat *statbuf UNUSED_PARAM,
 321                 void *userData,
 322                 int depth UNUSED_PARAM)
 323 {
 324         size_t len = strlen(fileName) - 4; /* can't underflow */
 325         char *scratch = userData;
 326
 327         /* len check is for paranoid reasons */
 328         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 329                 return FALSE;
 330
 331         strcpy(scratch, fileName);
 332         scratch[len] = '\0';
 333         make_device(scratch, 0);
 334
 335         return TRUE;
 336 }
 337
 338 /* Directory callback for /sys/ traversal */
 339 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 340                 struct stat *statbuf UNUSED_PARAM,
 341                 void *userData UNUSED_PARAM,
 342                 int depth)
 343 {
 344         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 345 }
 346
 347 /* For the full gory details, see linux/Documentation/firmware_class/README
 348  *
 349  * Firmware loading works like this:
 350  * - kernel sets FIRMWARE env var
 351  * - userspace checks /lib/firmware/$FIRMWARE
 352  * - userspace waits for /sys/$DEVPATH/loading to appear
 353  * - userspace writes "1" to /sys/$DEVPATH/loading
 354  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 355  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 356  * - kernel loads firmware into device
 357  */
 358 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 359 {
 360         int cnt;
 361         int firmware_fd, loading_fd, data_fd;
 362
 363         /* check for /lib/firmware/$FIRMWARE */
 364         xchdir("/lib/firmware");
 365         firmware_fd = xopen(firmware, O_RDONLY);
 366
 367         /* in case we goto out ... */
 368         data_fd = -1;
 369
 370         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 371         xchdir(sysfs_path);
 372         for (cnt = 0; cnt < 30; ++cnt) {
 373                 loading_fd = open("loading", O_WRONLY);
 374                 if (loading_fd != -1)
 375                         goto loading;
 376                 sleep(1);
 377         }
 378         goto out;
 379
 380  loading:
 381         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 382         if (full_write(loading_fd, "1", 1) != 1)
 383                 goto out;
 384
 385         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 386         data_fd = open("data", O_WRONLY);
 387         if (data_fd == -1)
 388                 goto out;
 389         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 390
 391         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 392         if (cnt > 0)
 393                 full_write(loading_fd, "0", 1);
 394         else
 395                 full_write(loading_fd, "-1", 2);
 396
 397  out:
 398         if (ENABLE_FEATURE_CLEAN_UP) {
 399                 close(firmware_fd);
 400                 close(loading_fd);
 401                 close(data_fd);
 402         }
 403 }
 404
 405 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 406 int mdev_main(int argc UNUSED_PARAM, char **argv)
 407 {
 408         char *action;
 409         char *env_path;
 410         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 411
 412         /* We can be called as hotplug helper */
 413         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 414 #if 1
 415         bb_sanitize_stdio();
 416 #else
 417         /* Debug code */
 418         /* Replace LOGFILE by other file or device name if you need */
 419 #define LOGFILE "/dev/console"
 420         /* Just making sure fd 0 is not closed,
 421          * we don't really intend to read from it */
 422         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 423         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 424         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 425 #endif
 426
 427         xchdir("/dev");
 428
 429         if (argv[1] && !strcmp(argv[1], "-s")) {
 430                 /* Scan:
 431                  * mdev -s
 432                  */
 433                 struct stat st;
 434
 435                 xstat("/", &st);
 436                 root_major = major(st.st_dev);
 437                 root_minor = minor(st.st_dev);
 438
 439                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 440                  * /sys/block/loop* (for example) are symlinks to dirs,
 441                  * not real directories.
 442                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 443                  * but we can't enforce that on users) */
 444                 recursive_action("/sys/block",
 445                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 446                         fileAction, dirAction, temp, 0);
 447                 recursive_action("/sys/class",
 448                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 449                         fileAction, dirAction, temp, 0);
 450         } else {
 451                 /* Hotplug:
 452                  * env ACTION=... DEVPATH=... mdev
 453                  * ACTION can be "add" or "remove"
 454                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 455                  */
 456                 action = getenv("ACTION");
 457                 env_path = getenv("DEVPATH");
 458                 if (!action || !env_path)
 459                         bb_show_usage();
 460
 461                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 462                 if (!strcmp(action, "remove"))
 463                         make_device(temp, 1);
 464                 else if (!strcmp(action, "add")) {
 465                         make_device(temp, 0);
 466
 467                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 468                                 char *fw = getenv("FIRMWARE");
 469                                 if (fw)
 470                                         load_firmware(fw, temp);
 471                         }
 472                 }
 473         }
 474
 475         if (ENABLE_FEATURE_CLEAN_UP)
 476                 RELEASE_CONFIG_BUFFER(temp);
 477
 478         return 0;
 479 }