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