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         type = (path[5] == 'c' ? S_IFCHR : S_IFBLK); /* "/sys/[c]lass"? */
  73
  74         if (ENABLE_FEATURE_MDEV_CONF) {
  75                 FILE *fp;
  76                 char *line, *val, *next;
  77                 unsigned lineno = 0;
  78
  79                 /* If we have config file, look up user settings */
  80                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  81                 if (!fp)
  82                         goto end_parse;
  83
  84                 while ((line = xmalloc_fgetline(fp)) != NULL) {
  85                         ++lineno;
  86                         trim(line);
  87                         if (!line[0])
  88                                 goto next_line;
  89
  90                         /* Fields: regex uid:gid mode [alias] [cmd] */
  91
  92                         /* 1st field: regex to match this device */
  93                         next = next_field(line);
  94                         {
  95                                 regex_t match;
  96                                 regmatch_t off;
  97                                 int result;
  98
  99                                 /* Is this it? */
 100                                 xregcomp(&match, line, REG_EXTENDED);
 101                                 result = regexec(&match, device_name, 1, &off, 0);
 102                                 regfree(&match);
 103
 104                                 /* If not this device, skip rest of line */
 105                                 if (result || off.rm_so || off.rm_eo != strlen(device_name))
 106                                         goto next_line;
 107                         }
 108
 109                         /* This line matches: stop parsing the file
 110                          * after parsing the rest of fields */
 111
 112                         /* 2nd field: uid:gid - device ownership */
 113                         if (!next) /* field must exist */
 114                                 bb_error_msg_and_die("bad line %u", lineno);
 115                         val = next;
 116                         next = next_field(val);
 117                         {
 118                                 struct passwd *pass;
 119                                 struct group *grp;
 120                                 char *str_uid = val;
 121                                 char *str_gid = strchrnul(val, ':');
 122
 123                                 if (*str_gid)
 124                                         *str_gid++ = '\0';
 125                                 /* Parse UID */
 126                                 pass = getpwnam(str_uid);
 127                                 if (pass)
 128                                         uid = pass->pw_uid;
 129                                 else
 130                                         uid = strtoul(str_uid, NULL, 10);
 131                                 /* Parse GID */
 132                                 grp = getgrnam(str_gid);
 133                                 if (grp)
 134                                         gid = grp->gr_gid;
 135                                 else
 136                                         gid = strtoul(str_gid, NULL, 10);
 137                         }
 138
 139                         /* 3rd field: mode - device permissions */
 140                         if (!next) /* field must exist */
 141                                 bb_error_msg_and_die("bad line %u", lineno);
 142                         val = next;
 143                         next = next_field(val);
 144                         mode = strtoul(val, NULL, 8);
 145
 146                         /* 4th field (opt): >alias */
 147                         if (ENABLE_FEATURE_MDEV_RENAME) {
 148                                 if (!next)
 149                                         break;
 150                                 val = next;
 151                                 next = next_field(val);
 152                                 if (*val == '>') {
 153                                         alias = xstrdup(val + 1);
 154                                 }
 155                         }
 156
 157                         /* The rest (opt): command to run */
 158                         if (!next)
 159                                 break;
 160                         val = next;
 161                         if (ENABLE_FEATURE_MDEV_EXEC) {
 162                                 const char *s = "@$*";
 163                                 const char *s2 = strchr(s, *val);
 164
 165                                 if (!s2)
 166                                         bb_error_msg_and_die("bad line %u", lineno);
 167
 168                                 /* Correlate the position in the "@$*" with the delete
 169                                  * step so that we get the proper behavior:
 170                                  * @cmd: run on create
 171                                  * $cmd: run on delete
 172                                  * *cmd: run on both
 173                                  */
 174                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 175                                         command = xstrdup(val + 1);
 176                                 }
 177                         }
 178                         /* end of field parsing */
 179                         break; /* we found matching line, stop */
 180  next_line:
 181                         free(line);
 182                 } /* end of "while line is read from /etc/mdev.conf" */
 183
 184                 free(line); /* in case we used "break" to get here */
 185                 fclose(fp);
 186         }
 187  end_parse:
 188
 189         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 190
 191                 if (ENABLE_FEATURE_MDEV_RENAME)
 192                         unlink(device_name);
 193
 194                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 195                         bb_perror_msg_and_die("mknod %s", device_name);
 196
 197                 if (major == root_major && minor == root_minor)
 198                         symlink(device_name, "root");
 199
 200                 if (ENABLE_FEATURE_MDEV_CONF) {
 201                         chown(device_name, uid, gid);
 202
 203                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 204                                 char *dest;
 205
 206                                 dest = strrchr(alias, '/');
 207                                 if (dest) {
 208                                         if (dest[1] != '\0')
 209                                                 /* given a file name, so rename it */
 210                                                 *dest = '\0';
 211                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 212                                         dest = concat_path_file(alias, device_name);
 213                                         free(alias);
 214                                 } else
 215                                         dest = alias;
 216
 217                                 rename(device_name, dest);
 218                                 symlink(dest, device_name);
 219
 220                                 free(dest);
 221                         }
 222                 }
 223         }
 224
 225         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 226                 /* setenv will leak memory, use putenv/unsetenv/free */
 227                 char *s = xasprintf("MDEV=%s", device_name);
 228                 putenv(s);
 229                 if (system(command) == -1)
 230                         bb_perror_msg_and_die("can't run '%s'", command);
 231                 s[4] = '\0';
 232                 unsetenv(s);
 233                 free(s);
 234                 free(command);
 235         }
 236
 237         if (delete)
 238                 unlink(device_name);
 239 }
 240
 241 /* File callback for /sys/ traversal */
 242 static int fileAction(const char *fileName,
 243                       struct stat *statbuf ATTRIBUTE_UNUSED,
 244                       void *userData,
 245                       int depth ATTRIBUTE_UNUSED)
 246 {
 247         size_t len = strlen(fileName) - 4; /* can't underflow */
 248         char *scratch = userData;
 249
 250         /* len check is for paranoid reasons */
 251         if (strcmp(fileName + len, "/dev") || len >= PATH_MAX)
 252                 return FALSE;
 253
 254         strcpy(scratch, fileName);
 255         scratch[len] = '\0';
 256         make_device(scratch, 0);
 257
 258         return TRUE;
 259 }
 260
 261 /* Directory callback for /sys/ traversal */
 262 static int dirAction(const char *fileName ATTRIBUTE_UNUSED,
 263                       struct stat *statbuf ATTRIBUTE_UNUSED,
 264                       void *userData ATTRIBUTE_UNUSED,
 265                       int depth)
 266 {
 267         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 268 }
 269
 270 /* For the full gory details, see linux/Documentation/firmware_class/README
 271  *
 272  * Firmware loading works like this:
 273  * - kernel sets FIRMWARE env var
 274  * - userspace checks /lib/firmware/$FIRMWARE
 275  * - userspace waits for /sys/$DEVPATH/loading to appear
 276  * - userspace writes "1" to /sys/$DEVPATH/loading
 277  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 278  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 279  * - kernel loads firmware into device
 280  */
 281 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 282 {
 283         int cnt;
 284         int firmware_fd, loading_fd, data_fd;
 285
 286         /* check for /lib/firmware/$FIRMWARE */
 287         xchdir("/lib/firmware");
 288         firmware_fd = xopen(firmware, O_RDONLY);
 289
 290         /* in case we goto out ... */
 291         data_fd = -1;
 292
 293         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 294         xchdir(sysfs_path);
 295         for (cnt = 0; cnt < 30; ++cnt) {
 296                 loading_fd = open("loading", O_WRONLY);
 297                 if (loading_fd != -1)
 298                         goto loading;
 299                 sleep(1);
 300         }
 301         goto out;
 302
 303  loading:
 304         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 305         if (full_write(loading_fd, "1", 1) != 1)
 306                 goto out;
 307
 308         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 309         data_fd = open("data", O_WRONLY);
 310         if (data_fd == -1)
 311                 goto out;
 312         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 313
 314         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 315         if (cnt > 0)
 316                 full_write(loading_fd, "0", 1);
 317         else
 318                 full_write(loading_fd, "-1", 2);
 319
 320  out:
 321         if (ENABLE_FEATURE_CLEAN_UP) {
 322                 close(firmware_fd);
 323                 close(loading_fd);
 324                 close(data_fd);
 325         }
 326 }
 327
 328 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 329 int mdev_main(int argc, char **argv)
 330 {
 331         char *action;
 332         char *env_path;
 333         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 334
 335         xchdir("/dev");
 336
 337         if (argc == 2 && !strcmp(argv[1], "-s")) {
 338                 /* Scan:
 339                  * mdev -s
 340                  */
 341                 struct stat st;
 342
 343                 xstat("/", &st);
 344                 root_major = major(st.st_dev);
 345                 root_minor = minor(st.st_dev);
 346
 347                 recursive_action("/sys/block",
 348                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 349                         fileAction, dirAction, temp, 0);
 350
 351                 recursive_action("/sys/class",
 352                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 353                         fileAction, dirAction, temp, 0);
 354
 355         } else {
 356                 /* Hotplug:
 357                  * env ACTION=... DEVPATH=... mdev
 358                  * ACTION can be "add" or "remove"
 359                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 360                  */
 361                 action = getenv("ACTION");
 362                 env_path = getenv("DEVPATH");
 363                 if (!action || !env_path)
 364                         bb_show_usage();
 365
 366                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 367                 if (!strcmp(action, "remove"))
 368                         make_device(temp, 1);
 369                 else if (!strcmp(action, "add")) {
 370                         make_device(temp, 0);
 371
 372                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 373                                 char *fw = getenv("FIRMWARE");
 374                                 if (fw)
 375                                         load_firmware(fw, temp);
 376                         }
 377                 }
 378         }
 379
 380         if (ENABLE_FEATURE_CLEAN_UP)
 381                 RELEASE_CONFIG_BUFFER(temp);
 382
 383         return 0;
 384 }