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