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          * Since kernel 2.6.25 block devices are also in /sys/class/block. */
 101         /* TODO: would it be acceptable to just use strstr(path, "/block/")? */
 102         if (strncmp(&path[5], "class/block/"+6, 6) != 0
 103          && strncmp(&path[5], "class/block/", 12) != 0)
 104                 type = S_IFCHR;
 105         else
 106                 type = S_IFBLK;
 107
 108         if (ENABLE_FEATURE_MDEV_CONF) {
 109                 FILE *fp;
 110                 char *line, *val, *next;
 111                 unsigned lineno = 0;
 112
 113                 /* If we have config file, look up user settings */
 114                 fp = fopen_or_warn("/etc/mdev.conf", "r");
 115                 if (!fp)
 116                         goto end_parse;
 117
 118                 while ((line = xmalloc_fgetline(fp)) != NULL) {
 119                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 120
 121                         ++lineno;
 122                         trim(line);
 123                         if (!line[0])
 124                                 goto next_line;
 125
 126                         /* Fields: regex uid:gid mode [alias] [cmd] */
 127
 128                         /* 1st field: regex to match this device */
 129                         next = next_field(line);
 130                         {
 131                                 regex_t match;
 132                                 int result;
 133
 134                                 /* Is this it? */
 135                                 xregcomp(&match, line, REG_EXTENDED);
 136                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 137                                 regfree(&match);
 138
 139                                 //bb_error_msg("matches:");
 140                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 141                                 //      if (off[i].rm_so < 0) continue;
 142                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 143                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 144                                 //              device_name + off[i].rm_so);
 145                                 //}
 146
 147                                 /* If not this device, skip rest of line */
 148                                 /* (regexec returns whole pattern as "range" 0) */
 149                                 if (result || off[0].rm_so
 150                                  || ((int)off[0].rm_eo != (int)strlen(device_name))
 151                                 ) {
 152                                         goto next_line;
 153                                 }
 154                         }
 155
 156                         /* This line matches: stop parsing the file
 157                          * after parsing the rest of fields */
 158
 159                         /* 2nd field: uid:gid - device ownership */
 160                         if (!next) /* field must exist */
 161                                 bb_error_msg_and_die("bad line %u", lineno);
 162                         val = next;
 163                         next = next_field(val);
 164                         {
 165                                 struct passwd *pass;
 166                                 struct group *grp;
 167                                 char *str_uid = val;
 168                                 char *str_gid = strchrnul(val, ':');
 169
 170                                 if (*str_gid)
 171                                         *str_gid++ = '\0';
 172                                 /* Parse UID */
 173                                 pass = getpwnam(str_uid);
 174                                 if (pass)
 175                                         uid = pass->pw_uid;
 176                                 else
 177                                         uid = strtoul(str_uid, NULL, 10);
 178                                 /* Parse GID */
 179                                 grp = getgrnam(str_gid);
 180                                 if (grp)
 181                                         gid = grp->gr_gid;
 182                                 else
 183                                         gid = strtoul(str_gid, NULL, 10);
 184                         }
 185
 186                         /* 3rd field: mode - device permissions */
 187                         if (!next) /* field must exist */
 188                                 bb_error_msg_and_die("bad line %u", lineno);
 189                         val = next;
 190                         next = next_field(val);
 191                         mode = strtoul(val, NULL, 8);
 192
 193                         /* 4th field (opt): >alias */
 194 #if ENABLE_FEATURE_MDEV_RENAME
 195                         if (!next)
 196                                 break;
 197                         if (*next == '>' || *next == '=') {
 198 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 199                                 char *s, *p;
 200                                 unsigned i, n;
 201
 202                                 aliaslink = *next;
 203                                 val = next;
 204                                 next = next_field(val);
 205                                 /* substitute %1..9 with off[1..9], if any */
 206                                 n = 0;
 207                                 s = val;
 208                                 while (*s)
 209                                         if (*s++ == '%')
 210                                                 n++;
 211
 212                                 p = alias = xzalloc(strlen(val) + n * strlen(device_name));
 213                                 s = val + 1;
 214                                 while (*s) {
 215                                         *p = *s;
 216                                         if ('%' == *s) {
 217                                                 i = (s[1] - '0');
 218                                                 if (i <= 9 && off[i].rm_so >= 0) {
 219                                                         n = off[i].rm_eo - off[i].rm_so;
 220                                                         strncpy(p, device_name + off[i].rm_so, n);
 221                                                         p += n - 1;
 222                                                         s++;
 223                                                 }
 224                                         }
 225                                         p++;
 226                                         s++;
 227                                 }
 228 #else
 229                                 aliaslink = *next;
 230                                 val = next;
 231                                 next = next_field(val);
 232                                 alias = xstrdup(val + 1);
 233 #endif
 234                         }
 235 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 236
 237                         /* The rest (opt): command to run */
 238                         if (!next)
 239                                 break;
 240                         val = next;
 241                         if (ENABLE_FEATURE_MDEV_EXEC) {
 242                                 const char *s = "@$*";
 243                                 const char *s2 = strchr(s, *val);
 244
 245                                 if (!s2)
 246                                         bb_error_msg_and_die("bad line %u", lineno);
 247
 248                                 /* Correlate the position in the "@$*" with the delete
 249                                  * step so that we get the proper behavior:
 250                                  * @cmd: run on create
 251                                  * $cmd: run on delete
 252                                  * *cmd: run on both
 253                                  */
 254                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 255                                         command = xstrdup(val + 1);
 256                                 }
 257                         }
 258                         /* end of field parsing */
 259                         break; /* we found matching line, stop */
 260  next_line:
 261                         free(line);
 262                 } /* end of "while line is read from /etc/mdev.conf" */
 263
 264                 free(line); /* in case we used "break" to get here */
 265                 fclose(fp);
 266         }
 267  end_parse:
 268
 269         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 270
 271                 if (ENABLE_FEATURE_MDEV_RENAME)
 272                         unlink(device_name);
 273
 274                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 275                         bb_perror_msg_and_die("mknod %s", device_name);
 276
 277                 if (major == root_major && minor == root_minor)
 278                         symlink(device_name, "root");
 279
 280                 if (ENABLE_FEATURE_MDEV_CONF) {
 281                         chown(device_name, uid, gid);
 282
 283                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 284                                 alias = build_alias(alias, device_name);
 285
 286                                 /* move the device, and optionally
 287                                  * make a symlink to moved device node */
 288                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 289                                         symlink(alias, device_name);
 290
 291                                 free(alias);
 292                         }
 293                 }
 294         }
 295
 296         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 297                 /* setenv will leak memory, use putenv/unsetenv/free */
 298                 char *s = xasprintf("MDEV=%s", device_name);
 299                 putenv(s);
 300                 if (system(command) == -1)
 301                         bb_perror_msg_and_die("can't run '%s'", command);
 302                 s[4] = '\0';
 303                 unsetenv(s);
 304                 free(s);
 305                 free(command);
 306         }
 307
 308         if (delete) {
 309                 unlink(device_name);
 310                 /* At creation time, device might have been moved
 311                  * and a symlink might have been created. Undo that. */
 312                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 313                         alias = build_alias(alias, device_name);
 314                         unlink(alias);
 315                         free(alias);
 316                 }
 317         }
 318 }
 319
 320 /* File callback for /sys/ traversal */
 321 static int FAST_FUNC fileAction(const char *fileName,
 322                 struct stat *statbuf UNUSED_PARAM,
 323                 void *userData,
 324                 int depth UNUSED_PARAM)
 325 {
 326         size_t len = strlen(fileName) - 4; /* can't underflow */
 327         char *scratch = userData;
 328
 329         /* len check is for paranoid reasons */
 330         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 331                 return FALSE;
 332
 333         strcpy(scratch, fileName);
 334         scratch[len] = '\0';
 335         make_device(scratch, 0);
 336
 337         return TRUE;
 338 }
 339
 340 /* Directory callback for /sys/ traversal */
 341 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 342                 struct stat *statbuf UNUSED_PARAM,
 343                 void *userData UNUSED_PARAM,
 344                 int depth)
 345 {
 346         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 347 }
 348
 349 /* For the full gory details, see linux/Documentation/firmware_class/README
 350  *
 351  * Firmware loading works like this:
 352  * - kernel sets FIRMWARE env var
 353  * - userspace checks /lib/firmware/$FIRMWARE
 354  * - userspace waits for /sys/$DEVPATH/loading to appear
 355  * - userspace writes "1" to /sys/$DEVPATH/loading
 356  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 357  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 358  * - kernel loads firmware into device
 359  */
 360 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 361 {
 362         int cnt;
 363         int firmware_fd, loading_fd, data_fd;
 364
 365         /* check for /lib/firmware/$FIRMWARE */
 366         xchdir("/lib/firmware");
 367         firmware_fd = xopen(firmware, O_RDONLY);
 368
 369         /* in case we goto out ... */
 370         data_fd = -1;
 371
 372         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 373         xchdir(sysfs_path);
 374         for (cnt = 0; cnt < 30; ++cnt) {
 375                 loading_fd = open("loading", O_WRONLY);
 376                 if (loading_fd != -1)
 377                         goto loading;
 378                 sleep(1);
 379         }
 380         goto out;
 381
 382  loading:
 383         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 384         if (full_write(loading_fd, "1", 1) != 1)
 385                 goto out;
 386
 387         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 388         data_fd = open("data", O_WRONLY);
 389         if (data_fd == -1)
 390                 goto out;
 391         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 392
 393         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 394         if (cnt > 0)
 395                 full_write(loading_fd, "0", 1);
 396         else
 397                 full_write(loading_fd, "-1", 2);
 398
 399  out:
 400         if (ENABLE_FEATURE_CLEAN_UP) {
 401                 close(firmware_fd);
 402                 close(loading_fd);
 403                 close(data_fd);
 404         }
 405 }
 406
 407 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 408 int mdev_main(int argc UNUSED_PARAM, char **argv)
 409 {
 410         char *action;
 411         char *env_path;
 412         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 413
 414         /* We can be called as hotplug helper */
 415         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 416 #if 1
 417         bb_sanitize_stdio();
 418 #else
 419         /* Debug code */
 420         /* Replace LOGFILE by other file or device name if you need */
 421 #define LOGFILE "/dev/console"
 422         /* Just making sure fd 0 is not closed,
 423          * we don't really intend to read from it */
 424         xmove_fd(xopen("/", O_RDONLY), STDIN_FILENO);
 425         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 426         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 427 #endif
 428
 429         xchdir("/dev");
 430
 431         if (argv[1] && !strcmp(argv[1], "-s")) {
 432                 /* Scan:
 433                  * mdev -s
 434                  */
 435                 struct stat st;
 436
 437                 xstat("/", &st);
 438                 root_major = major(st.st_dev);
 439                 root_minor = minor(st.st_dev);
 440
 441                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 442                  * /sys/block/loop* (for example) are symlinks to dirs,
 443                  * not real directories.
 444                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 445                  * but we can't enforce that on users) */
 446                 recursive_action("/sys/block",
 447                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 448                         fileAction, dirAction, temp, 0);
 449                 recursive_action("/sys/class",
 450                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 451                         fileAction, dirAction, temp, 0);
 452         } else {
 453                 /* Hotplug:
 454                  * env ACTION=... DEVPATH=... mdev
 455                  * ACTION can be "add" or "remove"
 456                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 457                  */
 458                 action = getenv("ACTION");
 459                 env_path = getenv("DEVPATH");
 460                 if (!action || !env_path)
 461                         bb_show_usage();
 462
 463                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 464                 if (!strcmp(action, "remove"))
 465                         make_device(temp, 1);
 466                 else if (!strcmp(action, "add")) {
 467                         make_device(temp, 0);
 468
 469                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 470                                 char *fw = getenv("FIRMWARE");
 471                                 if (fw)
 472                                         load_firmware(fw, temp);
 473                         }
 474                 }
 475         }
 476
 477         if (ENABLE_FEATURE_CLEAN_UP)
 478                 RELEASE_CONFIG_BUFFER(temp);
 479
 480         return 0;
 481 }