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 #define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
  23
  24 /* We use additional 64+ bytes in make_device() */
  25 #define SCRATCH_SIZE 80
  26
  27 static char *next_field(char *s)
  28 {
  29         char *end = skip_non_whitespace(s);
  30         s = skip_whitespace(end);
  31         *end = '\0';
  32         if (*s == '\0')
  33                 s = NULL;
  34         return s;
  35 }
  36
  37 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  38 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  39 static void make_device(char *path, int delete)
  40 {
  41         const char *device_name;
  42         int major, minor, type, len;
  43         int mode = 0660;
  44         uid_t uid = 0;
  45         gid_t gid = 0;
  46         char *dev_maj_min = path + strlen(path);
  47         char *command = NULL;
  48         char *alias = NULL;
  49         char aliaslink = aliaslink; /* for compiler */
  50
  51         /* Force the configuration file settings exactly. */
  52         umask(0);
  53
  54         /* Try to read major/minor string.  Note that the kernel puts \n after
  55          * the data, so we don't need to worry about null terminating the string
  56          * because sscanf() will stop at the first nondigit, which \n is.  We
  57          * also depend on path having writeable space after it.
  58          */
  59         if (!delete) {
  60                 strcpy(dev_maj_min, "/dev");
  61                 len = open_read_close(path, dev_maj_min + 1, 64);
  62                 *dev_maj_min++ = '\0';
  63                 if (len < 1) {
  64                         if (!ENABLE_FEATURE_MDEV_EXEC)
  65                                 return;
  66                         /* no "dev" file, so just try to run script */
  67                         *dev_maj_min = '\0';
  68                 }
  69         }
  70
  71         /* Determine device name, type, major and minor */
  72         device_name = bb_basename(path);
  73         /* http://kernel.org/doc/pending/hotplug.txt says that only
  74          * "/sys/block/..." is for block devices. "/sys/bus" etc is not!
  75          * Since kernel 2.6.25 block devices are also in /sys/class/block. */
  76         /* TODO: would it be acceptable to just use strstr(path, "/block/")? */
  77         if (strncmp(&path[5], "class/block/"+6, 6) != 0
  78          && strncmp(&path[5], "class/block/", 12) != 0)
  79                 type = S_IFCHR;
  80         else
  81                 type = S_IFBLK;
  82
  83         if (ENABLE_FEATURE_MDEV_CONF) {
  84                 FILE *fp;
  85                 char *line, *val, *next;
  86                 unsigned lineno = 0;
  87
  88                 /* If we have config file, look up user settings */
  89                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  90                 if (!fp)
  91                         goto end_parse;
  92
  93                 while ((line = xmalloc_fgetline(fp)) != NULL) {
  94                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
  95
  96                         ++lineno;
  97                         trim(line);
  98                         if (!line[0])
  99                                 goto next_line;
 100
 101                         /* Fields: regex uid:gid mode [alias] [cmd] */
 102
 103                         /* 1st field: regex to match this device */
 104                         next = next_field(line);
 105                         {
 106                                 regex_t match;
 107                                 int result;
 108
 109                                 /* Is this it? */
 110                                 xregcomp(&match, line, REG_EXTENDED);
 111                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 112                                 regfree(&match);
 113
 114                                 //bb_error_msg("matches:");
 115                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 116                                 //      if (off[i].rm_so < 0) continue;
 117                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 118                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 119                                 //              device_name + off[i].rm_so);
 120                                 //}
 121
 122                                 /* If not this device, skip rest of line */
 123                                 /* (regexec returns whole pattern as "range" 0) */
 124                                 if (result || off[0].rm_so
 125                                  || ((int)off[0].rm_eo != (int)strlen(device_name))
 126                                 ) {
 127                                         goto next_line;
 128                                 }
 129                         }
 130
 131                         /* This line matches: stop parsing the file
 132                          * after parsing the rest of fields */
 133
 134                         /* 2nd field: uid:gid - device ownership */
 135                         if (!next) /* field must exist */
 136                                 bb_error_msg_and_die("bad line %u", lineno);
 137                         val = next;
 138                         next = next_field(val);
 139                         {
 140                                 struct passwd *pass;
 141                                 struct group *grp;
 142                                 char *str_uid = val;
 143                                 char *str_gid = strchrnul(val, ':');
 144
 145                                 if (*str_gid)
 146                                         *str_gid++ = '\0';
 147                                 /* Parse UID */
 148                                 pass = getpwnam(str_uid);
 149                                 if (pass)
 150                                         uid = pass->pw_uid;
 151                                 else
 152                                         uid = strtoul(str_uid, NULL, 10);
 153                                 /* Parse GID */
 154                                 grp = getgrnam(str_gid);
 155                                 if (grp)
 156                                         gid = grp->gr_gid;
 157                                 else
 158                                         gid = strtoul(str_gid, NULL, 10);
 159                         }
 160
 161                         /* 3rd field: mode - device permissions */
 162                         if (!next) /* field must exist */
 163                                 bb_error_msg_and_die("bad line %u", lineno);
 164                         val = next;
 165                         next = next_field(val);
 166                         mode = strtoul(val, NULL, 8);
 167
 168                         /* 4th field (opt): >alias */
 169 #if ENABLE_FEATURE_MDEV_RENAME
 170                         if (!next)
 171                                 break;
 172                         if (*next == '>' || *next == '=') {
 173 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 174                                 char *s, *p;
 175                                 unsigned i, n;
 176
 177                                 aliaslink = *next;
 178                                 val = next;
 179                                 next = next_field(val);
 180                                 /* substitute %1..9 with off[1..9], if any */
 181                                 n = 0;
 182                                 s = val;
 183                                 while (*s)
 184                                         if (*s++ == '%')
 185                                                 n++;
 186
 187                                 p = alias = xzalloc(strlen(val) + n * strlen(device_name));
 188                                 s = val + 1;
 189                                 while (*s) {
 190                                         *p = *s;
 191                                         if ('%' == *s) {
 192                                                 i = (s[1] - '0');
 193                                                 if (i <= 9 && off[i].rm_so >= 0) {
 194                                                         n = off[i].rm_eo - off[i].rm_so;
 195                                                         strncpy(p, device_name + off[i].rm_so, n);
 196                                                         p += n - 1;
 197                                                         s++;
 198                                                 }
 199                                         }
 200                                         p++;
 201                                         s++;
 202                                 }
 203 #else
 204                                 aliaslink = *next;
 205                                 val = next;
 206                                 next = next_field(val);
 207                                 alias = xstrdup(val + 1);
 208 #endif
 209                         }
 210 #endif /* ENABLE_FEATURE_MDEV_RENAME */
 211
 212                         /* The rest (opt): command to run */
 213                         if (!next)
 214                                 break;
 215                         val = next;
 216                         if (ENABLE_FEATURE_MDEV_EXEC) {
 217                                 const char *s = "@$*";
 218                                 const char *s2 = strchr(s, *val);
 219
 220                                 if (!s2)
 221                                         bb_error_msg_and_die("bad line %u", lineno);
 222
 223                                 /* Correlate the position in the "@$*" with the delete
 224                                  * step so that we get the proper behavior:
 225                                  * @cmd: run on create
 226                                  * $cmd: run on delete
 227                                  * *cmd: run on both
 228                                  */
 229                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 230                                         command = xstrdup(val + 1);
 231                                 }
 232                         }
 233                         /* end of field parsing */
 234                         break; /* we found matching line, stop */
 235  next_line:
 236                         free(line);
 237                 } /* end of "while line is read from /etc/mdev.conf" */
 238
 239                 free(line); /* in case we used "break" to get here */
 240                 fclose(fp);
 241         }
 242  end_parse:
 243
 244         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 245
 246                 if (ENABLE_FEATURE_MDEV_RENAME)
 247                         unlink(device_name);
 248
 249                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 250                         bb_perror_msg_and_die("mknod %s", device_name);
 251
 252                 if (major == root_major && minor == root_minor)
 253                         symlink(device_name, "root");
 254
 255                 if (ENABLE_FEATURE_MDEV_CONF) {
 256                         chown(device_name, uid, gid);
 257
 258                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 259                                 char *dest;
 260
 261                                 /* ">bar/": rename to bar/device_name */
 262                                 /* ">bar[/]baz": rename to bar[/]baz */
 263                                 dest = strrchr(alias, '/');
 264                                 if (dest) { /* ">bar/[baz]" ? */
 265                                         *dest = '\0'; /* mkdir bar */
 266                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 267                                         *dest = '/';
 268                                         if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 269                                                 dest = alias;
 270                                                 alias = concat_path_file(alias, device_name);
 271                                                 free(dest);
 272                                         }
 273                                 }
 274
 275                                 /* move the device, and optionally
 276                                  * make a symlink to moved device node */
 277                                 if (rename(device_name, alias) == 0 && aliaslink == '>')
 278                                         symlink(alias, device_name);
 279
 280                                 free(alias);
 281                         }
 282                 }
 283         }
 284
 285         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 286                 /* setenv will leak memory, use putenv/unsetenv/free */
 287                 char *s = xasprintf("MDEV=%s", device_name);
 288                 putenv(s);
 289                 if (system(command) == -1)
 290                         bb_perror_msg_and_die("can't run '%s'", command);
 291                 s[4] = '\0';
 292                 unsetenv(s);
 293                 free(s);
 294                 free(command);
 295         }
 296
 297         if (delete)
 298                 unlink(device_name);
 299 }
 300
 301 /* File callback for /sys/ traversal */
 302 static int FAST_FUNC fileAction(const char *fileName,
 303                 struct stat *statbuf ATTRIBUTE_UNUSED,
 304                 void *userData,
 305                 int depth ATTRIBUTE_UNUSED)
 306 {
 307         size_t len = strlen(fileName) - 4; /* can't underflow */
 308         char *scratch = userData;
 309
 310         /* len check is for paranoid reasons */
 311         if (strcmp(fileName + len, "/dev") || len >= PATH_MAX)
 312                 return FALSE;
 313
 314         strcpy(scratch, fileName);
 315         scratch[len] = '\0';
 316         make_device(scratch, 0);
 317
 318         return TRUE;
 319 }
 320
 321 /* Directory callback for /sys/ traversal */
 322 static int FAST_FUNC dirAction(const char *fileName ATTRIBUTE_UNUSED,
 323                 struct stat *statbuf ATTRIBUTE_UNUSED,
 324                 void *userData ATTRIBUTE_UNUSED,
 325                 int depth)
 326 {
 327         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 328 }
 329
 330 /* For the full gory details, see linux/Documentation/firmware_class/README
 331  *
 332  * Firmware loading works like this:
 333  * - kernel sets FIRMWARE env var
 334  * - userspace checks /lib/firmware/$FIRMWARE
 335  * - userspace waits for /sys/$DEVPATH/loading to appear
 336  * - userspace writes "1" to /sys/$DEVPATH/loading
 337  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 338  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 339  * - kernel loads firmware into device
 340  */
 341 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 342 {
 343         int cnt;
 344         int firmware_fd, loading_fd, data_fd;
 345
 346         /* check for /lib/firmware/$FIRMWARE */
 347         xchdir("/lib/firmware");
 348         firmware_fd = xopen(firmware, O_RDONLY);
 349
 350         /* in case we goto out ... */
 351         data_fd = -1;
 352
 353         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 354         xchdir(sysfs_path);
 355         for (cnt = 0; cnt < 30; ++cnt) {
 356                 loading_fd = open("loading", O_WRONLY);
 357                 if (loading_fd != -1)
 358                         goto loading;
 359                 sleep(1);
 360         }
 361         goto out;
 362
 363  loading:
 364         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 365         if (full_write(loading_fd, "1", 1) != 1)
 366                 goto out;
 367
 368         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 369         data_fd = open("data", O_WRONLY);
 370         if (data_fd == -1)
 371                 goto out;
 372         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 373
 374         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 375         if (cnt > 0)
 376                 full_write(loading_fd, "0", 1);
 377         else
 378                 full_write(loading_fd, "-1", 2);
 379
 380  out:
 381         if (ENABLE_FEATURE_CLEAN_UP) {
 382                 close(firmware_fd);
 383                 close(loading_fd);
 384                 close(data_fd);
 385         }
 386 }
 387
 388 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 389 int mdev_main(int argc, char **argv)
 390 {
 391         char *action;
 392         char *env_path;
 393         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 394
 395 #ifdef YOU_WANT_TO_DEBUG_HOTPLUG_EVENTS
 396         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 397         /* Replace LOGFILE by other file or device name if you need */
 398 #define LOGFILE "/dev/console"
 399         xmove_fd(xopen("/dev/null", O_RDONLY), STDIN_FILENO);
 400         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDOUT_FILENO);
 401         xmove_fd(xopen(LOGFILE, O_WRONLY|O_APPEND), STDERR_FILENO);
 402 #endif
 403
 404         xchdir("/dev");
 405
 406         if (argc == 2 && !strcmp(argv[1], "-s")) {
 407                 /* Scan:
 408                  * mdev -s
 409                  */
 410                 struct stat st;
 411
 412                 xstat("/", &st);
 413                 root_major = major(st.st_dev);
 414                 root_minor = minor(st.st_dev);
 415
 416                 recursive_action("/sys/block",
 417                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 418                         fileAction, dirAction, temp, 0);
 419
 420                 recursive_action("/sys/class",
 421                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 422                         fileAction, dirAction, temp, 0);
 423
 424         } else {
 425                 /* Hotplug:
 426                  * env ACTION=... DEVPATH=... mdev
 427                  * ACTION can be "add" or "remove"
 428                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 429                  */
 430                 action = getenv("ACTION");
 431                 env_path = getenv("DEVPATH");
 432                 if (!action || !env_path)
 433                         bb_show_usage();
 434
 435                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 436                 if (!strcmp(action, "remove"))
 437                         make_device(temp, 1);
 438                 else if (!strcmp(action, "add")) {
 439                         make_device(temp, 0);
 440
 441                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 442                                 char *fw = getenv("FIRMWARE");
 443                                 if (fw)
 444                                         load_firmware(fw, temp);
 445                         }
 446                 }
 447         }
 448
 449         if (ENABLE_FEATURE_CLEAN_UP)
 450                 RELEASE_CONFIG_BUFFER(temp);
 451
 452         return 0;
 453 }