util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * mdev - Mini udev for busybox
   4  *
   5  * Copyright 2005 Rob Landley <rob@landley.net>
   6  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   7  *
   8  * Licensed under GPLv2, see file LICENSE in this source tree.
   9  */
  10
  11 //config:config MDEV
  12 //config:       bool "mdev (16 kb)"
  13 //config:       default y
  14 //config:       select PLATFORM_LINUX
  15 //config:       help
  16 //config:       mdev is a mini-udev implementation for dynamically creating device
  17 //config:       nodes in the /dev directory.
  18 //config:
  19 //config:       For more information, please see docs/mdev.txt
  20 //config:
  21 //config:config FEATURE_MDEV_CONF
  22 //config:       bool "Support /etc/mdev.conf"
  23 //config:       default y
  24 //config:       depends on MDEV
  25 //config:       help
  26 //config:       Add support for the mdev config file to control ownership and
  27 //config:       permissions of the device nodes.
  28 //config:
  29 //config:       For more information, please see docs/mdev.txt
  30 //config:
  31 //config:config FEATURE_MDEV_RENAME
  32 //config:       bool "Support subdirs/symlinks"
  33 //config:       default y
  34 //config:       depends on FEATURE_MDEV_CONF
  35 //config:       help
  36 //config:       Add support for renaming devices and creating symlinks.
  37 //config:
  38 //config:       For more information, please see docs/mdev.txt
  39 //config:
  40 //config:config FEATURE_MDEV_RENAME_REGEXP
  41 //config:       bool "Support regular expressions substitutions when renaming device"
  42 //config:       default y
  43 //config:       depends on FEATURE_MDEV_RENAME
  44 //config:       help
  45 //config:       Add support for regular expressions substitutions when renaming
  46 //config:       device.
  47 //config:
  48 //config:config FEATURE_MDEV_EXEC
  49 //config:       bool "Support command execution at device addition/removal"
  50 //config:       default y
  51 //config:       depends on FEATURE_MDEV_CONF
  52 //config:       help
  53 //config:       This adds support for an optional field to /etc/mdev.conf for
  54 //config:       executing commands when devices are created/removed.
  55 //config:
  56 //config:       For more information, please see docs/mdev.txt
  57 //config:
  58 //config:config FEATURE_MDEV_LOAD_FIRMWARE
  59 //config:       bool "Support loading of firmware"
  60 //config:       default y
  61 //config:       depends on MDEV
  62 //config:       help
  63 //config:       Some devices need to load firmware before they can be usable.
  64 //config:
  65 //config:       These devices will request userspace look up the files in
  66 //config:       /lib/firmware/ and if it exists, send it to the kernel for
  67 //config:       loading into the hardware.
  68
  69 //applet:IF_MDEV(APPLET(mdev, BB_DIR_SBIN, BB_SUID_DROP))
  70
  71 //kbuild:lib-$(CONFIG_MDEV) += mdev.o
  72
  73 //usage:#define mdev_trivial_usage
  74 //usage:       "[-s]"
  75 //usage:#define mdev_full_usage "\n\n"
  76 //usage:       "mdev -s is to be run during boot to scan /sys and populate /dev.\n"
  77 //usage:       "\n"
  78 //usage:       "Bare mdev is a kernel hotplug helper. To activate it:\n"
  79 //usage:       "        echo /sbin/mdev >/proc/sys/kernel/hotplug\n"
  80 //usage:        IF_FEATURE_MDEV_CONF(
  81 //usage:       "\n"
  82 //usage:       "It uses /etc/mdev.conf with lines\n"
  83 //usage:       "        [-][ENV=regex;]...DEVNAME UID:GID PERM"
  84 //usage:                        IF_FEATURE_MDEV_RENAME(" [>|=PATH]|[!]")
  85 //usage:                        IF_FEATURE_MDEV_EXEC(" [@|$|*PROG]")
  86 //usage:       "\n"
  87 //usage:       "where DEVNAME is device name regex, @major,minor[-minor2], or\n"
  88 //usage:       "environment variable regex. A common use of the latter is\n"
  89 //usage:       "to load modules for hotplugged devices:\n"
  90 //usage:       "        $MODALIAS=.* 0:0 660 @modprobe \"$MODALIAS\"\n"
  91 //usage:        )
  92 //usage:       "\n"
  93 //usage:       "If /dev/mdev.seq file exists, mdev will wait for its value\n"
  94 //usage:       "to match $SEQNUM variable. This prevents plug/unplug races.\n"
  95 //usage:       "To activate this feature, create empty /dev/mdev.seq at boot.\n"
  96 //usage:       "\n"
  97 //usage:       "If /dev/mdev.log file exists, debug log will be appended to it."
  98
  99 #include "libbb.h"
 100 #include "common_bufsiz.h"
 101 #include "xregex.h"
 102
 103 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
 104  * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
 105  * contains "4:0\n". Directory name is taken as device name, path component
 106  * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
 107  * Then mdev creates the /dev/device_name node.
 108  * If /sys/class/.../dev file does not exist, mdev still may act
 109  * on this device: see "@|$|*command args..." parameter in config file.
 110  *
 111  * mdev w/o parameters is called as hotplug helper. It takes device
 112  * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
 113  * maj,min from "/sys/$DEVPATH/dev" and also examines
 114  * $ACTION ("add"/"delete") and $FIRMWARE.
 115  *
 116  * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
 117  * (todo: explain "delete" and $FIRMWARE)
 118  *
 119  * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
 120  *
 121  * Leading minus in 1st field means "don't stop on this line", otherwise
 122  * search is stopped after the matching line is encountered.
 123  *
 124  * $envvar=regex format is useful for loading modules for hot-plugged devices
 125  * which do not have driver loaded yet. In this case /sys/class/.../dev
 126  * does not exist, but $MODALIAS is set to needed module's name
 127  * (actually, an alias to it) by kernel. This rule instructs mdev
 128  * to load the module and exit:
 129  *    $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
 130  * The kernel will generate another hotplug event when /sys/class/.../dev
 131  * file appears.
 132  *
 133  * When line matches, the device node is created, chmod'ed and chown'ed,
 134  * moved to path, and if >path, a symlink to moved node is created,
 135  * all this if /sys/class/.../dev exists.
 136  *    Examples:
 137  *    =loop/      - moves to /dev/loop
 138  *    >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
 139  *
 140  * Then "command args..." is executed (via sh -c 'command args...').
 141  * @:execute on creation, $:on deletion, *:on both.
 142  * This happens regardless of /sys/class/.../dev existence.
 143  */
 144
 145 /* Kernel's hotplug environment constantly changes.
 146  * Here are new cases I observed on 3.1.0:
 147  *
 148  * Case with $DEVNAME and $DEVICE, not just $DEVPATH:
 149  * ACTION=add
 150  * BUSNUM=001
 151  * DEVICE=/proc/bus/usb/001/003
 152  * DEVNAME=bus/usb/001/003
 153  * DEVNUM=003
 154  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5
 155  * DEVTYPE=usb_device
 156  * MAJOR=189
 157  * MINOR=2
 158  * PRODUCT=18d1/4e12/227
 159  * SUBSYSTEM=usb
 160  * TYPE=0/0/0
 161  *
 162  * Case with $DEVICE, but no $DEVNAME - apparenty, usb iface notification?
 163  * "Please load me a module" thing?
 164  * ACTION=add
 165  * DEVICE=/proc/bus/usb/001/003
 166  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0
 167  * DEVTYPE=usb_interface
 168  * INTERFACE=8/6/80
 169  * MODALIAS=usb:v18D1p4E12d0227dc00dsc00dp00ic08isc06ip50
 170  * PRODUCT=18d1/4e12/227
 171  * SUBSYSTEM=usb
 172  * TYPE=0/0/0
 173  *
 174  * ACTION=add
 175  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5
 176  * DEVTYPE=scsi_host
 177  * SUBSYSTEM=scsi
 178  *
 179  * ACTION=add
 180  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/scsi_host/host5
 181  * SUBSYSTEM=scsi_host
 182  *
 183  * ACTION=add
 184  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0
 185  * DEVTYPE=scsi_target
 186  * SUBSYSTEM=scsi
 187  *
 188  * Case with strange $MODALIAS:
 189  * ACTION=add
 190  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0
 191  * DEVTYPE=scsi_device
 192  * MODALIAS=scsi:t-0x00
 193  * SUBSYSTEM=scsi
 194  *
 195  * ACTION=add
 196  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/scsi_disk/5:0:0:0
 197  * SUBSYSTEM=scsi_disk
 198  *
 199  * ACTION=add
 200  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/scsi_device/5:0:0:0
 201  * SUBSYSTEM=scsi_device
 202  *
 203  * Case with explicit $MAJOR/$MINOR (no need to read /sys/$DEVPATH/dev?):
 204  * ACTION=add
 205  * DEVNAME=bsg/5:0:0:0
 206  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/bsg/5:0:0:0
 207  * MAJOR=253
 208  * MINOR=1
 209  * SUBSYSTEM=bsg
 210  *
 211  * ACTION=add
 212  * DEVPATH=/devices/virtual/bdi/8:16
 213  * SUBSYSTEM=bdi
 214  *
 215  * ACTION=add
 216  * DEVNAME=sdb
 217  * DEVPATH=/block/sdb
 218  * DEVTYPE=disk
 219  * MAJOR=8
 220  * MINOR=16
 221  * SUBSYSTEM=block
 222  *
 223  * Case with ACTION=change:
 224  * ACTION=change
 225  * DEVNAME=sdb
 226  * DEVPATH=/block/sdb
 227  * DEVTYPE=disk
 228  * DISK_MEDIA_CHANGE=1
 229  * MAJOR=8
 230  * MINOR=16
 231  * SUBSYSTEM=block
 232  */
 233
 234 #define DEBUG_LVL 2
 235
 236 #if DEBUG_LVL >= 1
 237 # define dbg1(...) do { if (G.verbose) bb_error_msg(__VA_ARGS__); } while(0)
 238 #else
 239 # define dbg1(...) ((void)0)
 240 #endif
 241 #if DEBUG_LVL >= 2
 242 # define dbg2(...) do { if (G.verbose >= 2) bb_error_msg(__VA_ARGS__); } while(0)
 243 #else
 244 # define dbg2(...) ((void)0)
 245 #endif
 246 #if DEBUG_LVL >= 3
 247 # define dbg3(...) do { if (G.verbose >= 3) bb_error_msg(__VA_ARGS__); } while(0)
 248 #else
 249 # define dbg3(...) ((void)0)
 250 #endif
 251
 252
 253 static const char keywords[] ALIGN1 = "add\0remove\0"; // "change\0"
 254 enum { OP_add, OP_remove };
 255
 256 struct envmatch {
 257         struct envmatch *next;
 258         char *envname;
 259         regex_t match;
 260 };
 261
 262 struct rule {
 263         bool keep_matching;
 264         bool regex_compiled;
 265         mode_t mode;
 266         int maj, min0, min1;
 267         struct bb_uidgid_t ugid;
 268         char *envvar;
 269         char *ren_mov;
 270         IF_FEATURE_MDEV_EXEC(char *r_cmd;)
 271         regex_t match;
 272         struct envmatch *envmatch;
 273 };
 274
 275 struct globals {
 276         int root_major, root_minor;
 277         smallint verbose;
 278         char *subsystem;
 279         char *subsys_env; /* for putenv("SUBSYSTEM=subsystem") */
 280 #if ENABLE_FEATURE_MDEV_CONF
 281         const char *filename;
 282         parser_t *parser;
 283         struct rule **rule_vec;
 284         unsigned rule_idx;
 285 #endif
 286         struct rule cur_rule;
 287         char timestr[sizeof("HH:MM:SS.123456")];
 288 } FIX_ALIASING;
 289 #define G (*(struct globals*)bb_common_bufsiz1)
 290 #define INIT_G() do { \
 291         setup_common_bufsiz(); \
 292         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.maj = -1;) \
 293         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.mode = 0660;) \
 294 } while (0)
 295
 296
 297 /* Prevent infinite loops in /sys symlinks */
 298 #define MAX_SYSFS_DEPTH 3
 299
 300 /* We use additional bytes in make_device() */
 301 #define SCRATCH_SIZE 128
 302
 303 #if ENABLE_FEATURE_MDEV_CONF
 304
 305 static void make_default_cur_rule(void)
 306 {
 307         memset(&G.cur_rule, 0, sizeof(G.cur_rule));
 308         G.cur_rule.maj = -1; /* "not a @major,minor rule" */
 309         G.cur_rule.mode = 0660;
 310 }
 311
 312 static void clean_up_cur_rule(void)
 313 {
 314         struct envmatch *e;
 315
 316         free(G.cur_rule.envvar);
 317         free(G.cur_rule.ren_mov);
 318         if (G.cur_rule.regex_compiled)
 319                 regfree(&G.cur_rule.match);
 320         IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
 321         e = G.cur_rule.envmatch;
 322         while (e) {
 323                 free(e->envname);
 324                 regfree(&e->match);
 325                 e = e->next;
 326         }
 327         make_default_cur_rule();
 328 }
 329
 330 static char *parse_envmatch_pfx(char *val)
 331 {
 332         struct envmatch **nextp = &G.cur_rule.envmatch;
 333
 334         for (;;) {
 335                 struct envmatch *e;
 336                 char *semicolon;
 337                 char *eq = strchr(val, '=');
 338                 if (!eq /* || eq == val? */)
 339                         return val;
 340                 if (endofname(val) != eq)
 341                         return val;
 342                 semicolon = strchr(eq, ';');
 343                 if (!semicolon)
 344                         return val;
 345                 /* ENVVAR=regex;... */
 346                 *nextp = e = xzalloc(sizeof(*e));
 347                 nextp = &e->next;
 348                 e->envname = xstrndup(val, eq - val);
 349                 *semicolon = '\0';
 350                 xregcomp(&e->match, eq + 1, REG_EXTENDED);
 351                 *semicolon = ';';
 352                 val = semicolon + 1;
 353         }
 354 }
 355
 356 static void parse_next_rule(void)
 357 {
 358         /* Note: on entry, G.cur_rule is set to default */
 359         while (1) {
 360                 char *tokens[4];
 361                 char *val;
 362
 363                 /* No PARSE_EOL_COMMENTS, because command may contain '#' chars */
 364                 if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL & ~PARSE_EOL_COMMENTS))
 365                         break;
 366
 367                 /* Fields: [-]regex uid:gid mode [alias] [cmd] */
 368                 dbg3("token1:'%s'", tokens[1]);
 369
 370                 /* 1st field */
 371                 val = tokens[0];
 372                 G.cur_rule.keep_matching = ('-' == val[0]);
 373                 val += G.cur_rule.keep_matching; /* swallow leading dash */
 374                 val = parse_envmatch_pfx(val);
 375                 if (val[0] == '@') {
 376                         /* @major,minor[-minor2] */
 377                         /* (useful when name is ambiguous:
 378                          * "/sys/class/usb/lp0" and
 379                          * "/sys/class/printer/lp0")
 380                          */
 381                         int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
 382                         if (sc < 2 || G.cur_rule.maj < 0) {
 383                                 bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
 384                                 goto next_rule;
 385                         }
 386                         if (sc == 2)
 387                                 G.cur_rule.min1 = G.cur_rule.min0;
 388                 } else {
 389                         char *eq = strchr(val, '=');
 390                         if (val[0] == '$') {
 391                                 /* $ENVVAR=regex ... */
 392                                 val++;
 393                                 if (!eq) {
 394                                         bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
 395                                         goto next_rule;
 396                                 }
 397                                 G.cur_rule.envvar = xstrndup(val, eq - val);
 398                                 val = eq + 1;
 399                         }
 400                         xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
 401                         G.cur_rule.regex_compiled = 1;
 402                 }
 403
 404                 /* 2nd field: uid:gid - device ownership */
 405                 if (get_uidgid(&G.cur_rule.ugid, tokens[1]) == 0) {
 406                         bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
 407                         goto next_rule;
 408                 }
 409
 410                 /* 3rd field: mode - device permissions */
 411                 G.cur_rule.mode = bb_parse_mode(tokens[2], G.cur_rule.mode);
 412
 413                 /* 4th field (opt): ">|=alias" or "!" to not create the node */
 414                 val = tokens[3];
 415                 if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
 416                         char *s = skip_non_whitespace(val);
 417                         G.cur_rule.ren_mov = xstrndup(val, s - val);
 418                         val = skip_whitespace(s);
 419                 }
 420
 421                 if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
 422                         const char *s = "$@*";
 423                         const char *s2 = strchr(s, val[0]);
 424                         if (!s2) {
 425                                 bb_error_msg("bad line %u", G.parser->lineno);
 426                                 goto next_rule;
 427                         }
 428                         IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
 429                 }
 430
 431                 return;
 432  next_rule:
 433                 clean_up_cur_rule();
 434         } /* while (config_read) */
 435
 436         dbg3("config_close(G.parser)");
 437         config_close(G.parser);
 438         G.parser = NULL;
 439
 440         return;
 441 }
 442
 443 /* If mdev -s, we remember rules in G.rule_vec[].
 444  * Otherwise, there is no point in doing it, and we just
 445  * save only one parsed rule in G.cur_rule.
 446  */
 447 static const struct rule *next_rule(void)
 448 {
 449         struct rule *rule;
 450
 451         /* Open conf file if we didn't do it yet */
 452         if (!G.parser && G.filename) {
 453                 dbg3("config_open('%s')", G.filename);
 454                 G.parser = config_open2(G.filename, fopen_for_read);
 455                 G.filename = NULL;
 456         }
 457
 458         if (G.rule_vec) {
 459                 /* mdev -s */
 460                 /* Do we have rule parsed already? */
 461                 if (G.rule_vec[G.rule_idx]) {
 462                         dbg3("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 463                         return G.rule_vec[G.rule_idx++];
 464                 }
 465                 make_default_cur_rule();
 466         } else {
 467                 /* not mdev -s */
 468                 clean_up_cur_rule();
 469         }
 470
 471         /* Parse one more rule if file isn't fully read */
 472         rule = &G.cur_rule;
 473         if (G.parser) {
 474                 parse_next_rule();
 475                 if (G.rule_vec) { /* mdev -s */
 476                         rule = xmemdup(&G.cur_rule, sizeof(G.cur_rule));
 477                         G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
 478                         G.rule_vec[G.rule_idx++] = rule;
 479                         dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 480                 }
 481         }
 482
 483         return rule;
 484 }
 485
 486 static int env_matches(struct envmatch *e)
 487 {
 488         while (e) {
 489                 int r;
 490                 char *val = getenv(e->envname);
 491                 if (!val)
 492                         return 0;
 493                 r = regexec(&e->match, val, /*size*/ 0, /*range[]*/ NULL, /*eflags*/ 0);
 494                 if (r != 0) /* no match */
 495                         return 0;
 496                 e = e->next;
 497         }
 498         return 1;
 499 }
 500
 501 #else
 502
 503 # define next_rule() (&G.cur_rule)
 504
 505 #endif
 506
 507 static void mkdir_recursive(char *name)
 508 {
 509         /* if name has many levels ("dir1/dir2"),
 510          * bb_make_directory() will create dir1 according to umask,
 511          * not according to its "mode" parameter.
 512          * Since we run with umask=0, need to temporarily switch it.
 513          */
 514         umask(022); /* "dir1" (if any) will be 0755 too */
 515         bb_make_directory(name, 0755, FILEUTILS_RECUR);
 516         umask(0);
 517 }
 518
 519 /* Builds an alias path.
 520  * This function potentionally reallocates the alias parameter.
 521  * Only used for ENABLE_FEATURE_MDEV_RENAME
 522  */
 523 static char *build_alias(char *alias, const char *device_name)
 524 {
 525         char *dest;
 526
 527         /* ">bar/": rename to bar/device_name */
 528         /* ">bar[/]baz": rename to bar[/]baz */
 529         dest = strrchr(alias, '/');
 530         if (dest) { /* ">bar/[baz]" ? */
 531                 *dest = '\0'; /* mkdir bar */
 532                 mkdir_recursive(alias);
 533                 *dest = '/';
 534                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 535                         dest = alias;
 536                         alias = concat_path_file(alias, device_name);
 537                         free(dest);
 538                 }
 539         }
 540
 541         return alias;
 542 }
 543
 544 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
 545  * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
 546  * after NUL, but we promise to not mangle it (IOW: to restore NUL if needed).
 547  * NB2: "mdev -s" may call us many times, do not leak memory/fds!
 548  *
 549  * device_name = $DEVNAME (may be NULL)
 550  * path        = /sys/$DEVPATH
 551  */
 552 static void make_device(char *device_name, char *path, int operation)
 553 {
 554         int major, minor, type, len;
 555         char *path_end = path + strlen(path);
 556
 557         /* Try to read major/minor string.  Note that the kernel puts \n after
 558          * the data, so we don't need to worry about null terminating the string
 559          * because sscanf() will stop at the first nondigit, which \n is.
 560          * We also depend on path having writeable space after it.
 561          */
 562         major = -1;
 563         if (operation == OP_add) {
 564                 strcpy(path_end, "/dev");
 565                 len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
 566                 *path_end = '\0';
 567                 if (len < 1) {
 568                         if (!ENABLE_FEATURE_MDEV_EXEC)
 569                                 return;
 570                         /* no "dev" file, but we can still run scripts
 571                          * based on device name */
 572                 } else if (sscanf(path_end + 1, "%u:%u", &major, &minor) == 2) {
 573                         dbg1("dev %u,%u", major, minor);
 574                 } else {
 575                         major = -1;
 576                 }
 577         }
 578         /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
 579
 580         /* Determine device name */
 581         if (!device_name) {
 582                 /*
 583                  * There was no $DEVNAME envvar (for example, mdev -s never has).
 584                  * But it is very useful: it contains the *path*, not only basename,
 585                  * Thankfully, uevent file has it.
 586                  * Example of .../sound/card0/controlC0/uevent file on Linux-3.7.7:
 587                  * MAJOR=116
 588                  * MINOR=7
 589                  * DEVNAME=snd/controlC0
 590                  */
 591                 strcpy(path_end, "/uevent");
 592                 len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
 593                 if (len < 0)
 594                         len = 0;
 595                 *path_end = '\0';
 596                 path_end[1 + len] = '\0';
 597                 device_name = strstr(path_end + 1, "\nDEVNAME=");
 598                 if (device_name) {
 599                         device_name += sizeof("\nDEVNAME=")-1;
 600                         strchrnul(device_name, '\n')[0] = '\0';
 601                 } else {
 602                         /* Fall back to just basename */
 603                         device_name = (char*) bb_basename(path);
 604                 }
 605         }
 606         /* Determine device type */
 607         /*
 608          * http://kernel.org/doc/pending/hotplug.txt says that only
 609          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 610          * But since 2.6.25 block devices are also in /sys/class/block.
 611          * We use strstr("/block/") to forestall future surprises.
 612          */
 613         type = S_IFCHR;
 614         if (strstr(path, "/block/") || (G.subsystem && is_prefixed_with(G.subsystem, "block")))
 615                 type = S_IFBLK;
 616
 617 #if ENABLE_FEATURE_MDEV_CONF
 618         G.rule_idx = 0; /* restart from the beginning (think mdev -s) */
 619 #endif
 620         for (;;) {
 621                 const char *str_to_match;
 622                 regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 623                 char *command;
 624                 char *alias;
 625                 char aliaslink = aliaslink; /* for compiler */
 626                 char *node_name;
 627                 const struct rule *rule;
 628
 629                 str_to_match = device_name;
 630
 631                 rule = next_rule();
 632
 633 #if ENABLE_FEATURE_MDEV_CONF
 634                 if (!env_matches(rule->envmatch))
 635                         continue;
 636                 if (rule->maj >= 0) {  /* @maj,min rule */
 637                         if (major != rule->maj)
 638                                 continue;
 639                         if (minor < rule->min0 || minor > rule->min1)
 640                                 continue;
 641                         memset(off, 0, sizeof(off));
 642                         goto rule_matches;
 643                 }
 644                 if (rule->envvar) { /* $envvar=regex rule */
 645                         str_to_match = getenv(rule->envvar);
 646                         dbg3("getenv('%s'):'%s'", rule->envvar, str_to_match);
 647                         if (!str_to_match)
 648                                 continue;
 649                 }
 650                 /* else: str_to_match = device_name */
 651
 652                 if (rule->regex_compiled) {
 653                         int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0);
 654                         dbg3("regex_match for '%s':%d", str_to_match, regex_match);
 655                         //bb_error_msg("matches:");
 656                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 657                         //      if (off[i].rm_so < 0) continue;
 658                         //      bb_error_msg("match %d: '%.*s'\n", i,
 659                         //              (int)(off[i].rm_eo - off[i].rm_so),
 660                         //              device_name + off[i].rm_so);
 661                         //}
 662
 663                         if (regex_match != 0
 664                         /* regexec returns whole pattern as "range" 0 */
 665                          || off[0].rm_so != 0
 666                          || (int)off[0].rm_eo != (int)strlen(str_to_match)
 667                         ) {
 668                                 continue; /* this rule doesn't match */
 669                         }
 670                 }
 671                 /* else: it's final implicit "match-all" rule */
 672  rule_matches:
 673                 dbg2("rule matched, line %d", G.parser ? G.parser->lineno : -1);
 674 #endif
 675                 /* Build alias name */
 676                 alias = NULL;
 677                 if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) {
 678                         aliaslink = rule->ren_mov[0];
 679                         if (aliaslink == '!') {
 680                                 /* "!": suppress node creation/deletion */
 681                                 major = -2;
 682                         }
 683                         else if (aliaslink == '>' || aliaslink == '=') {
 684                                 if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
 685                                         char *s;
 686                                         char *p;
 687                                         unsigned n;
 688
 689                                         /* substitute %1..9 with off[1..9], if any */
 690                                         n = 0;
 691                                         s = rule->ren_mov;
 692                                         while (*s)
 693                                                 if (*s++ == '%')
 694                                                         n++;
 695
 696                                         p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match));
 697                                         s = rule->ren_mov + 1;
 698                                         while (*s) {
 699                                                 *p = *s;
 700                                                 if ('%' == *s) {
 701                                                         unsigned i = (s[1] - '0');
 702                                                         if (i <= 9 && off[i].rm_so >= 0) {
 703                                                                 n = off[i].rm_eo - off[i].rm_so;
 704                                                                 strncpy(p, str_to_match + off[i].rm_so, n);
 705                                                                 p += n - 1;
 706                                                                 s++;
 707                                                         }
 708                                                 }
 709                                                 p++;
 710                                                 s++;
 711                                         }
 712                                 } else {
 713                                         alias = xstrdup(rule->ren_mov + 1);
 714                                 }
 715                         }
 716                 }
 717                 dbg3("alias:'%s'", alias);
 718
 719                 command = NULL;
 720                 IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;)
 721                 if (command) {
 722                         /* Are we running this command now?
 723                          * Run @cmd on create, $cmd on delete, *cmd on any
 724                          */
 725                         if ((command[0] == '@' && operation == OP_add)
 726                          || (command[0] == '$' && operation == OP_remove)
 727                          || (command[0] == '*')
 728                         ) {
 729                                 command++;
 730                         } else {
 731                                 command = NULL;
 732                         }
 733                 }
 734                 dbg3("command:'%s'", command);
 735
 736                 /* "Execute" the line we found */
 737                 node_name = device_name;
 738                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 739                         node_name = alias = build_alias(alias, device_name);
 740                         dbg3("alias2:'%s'", alias);
 741                 }
 742
 743                 if (operation == OP_add && major >= 0) {
 744                         char *slash = strrchr(node_name, '/');
 745                         if (slash) {
 746                                 *slash = '\0';
 747                                 mkdir_recursive(node_name);
 748                                 *slash = '/';
 749                         }
 750                         if (ENABLE_FEATURE_MDEV_CONF) {
 751                                 dbg1("mknod %s (%d,%d) %o"
 752                                         " %u:%u",
 753                                         node_name, major, minor, rule->mode | type,
 754                                         rule->ugid.uid, rule->ugid.gid
 755                                 );
 756                         } else {
 757                                 dbg1("mknod %s (%d,%d) %o",
 758                                         node_name, major, minor, rule->mode | type
 759                                 );
 760                         }
 761                         if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST)
 762                                 bb_perror_msg("can't create '%s'", node_name);
 763                         if (ENABLE_FEATURE_MDEV_CONF) {
 764                                 chmod(node_name, rule->mode);
 765                                 chown(node_name, rule->ugid.uid, rule->ugid.gid);
 766                         }
 767                         if (major == G.root_major && minor == G.root_minor)
 768                                 symlink(node_name, "root");
 769                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 770                                 if (aliaslink == '>') {
 771 //TODO: on devtmpfs, device_name already exists and symlink() fails.
 772 //End result is that instead of symlink, we have two nodes.
 773 //What should be done?
 774                                         dbg1("symlink: %s", device_name);
 775                                         symlink(node_name, device_name);
 776                                 }
 777                         }
 778                 }
 779
 780                 if (ENABLE_FEATURE_MDEV_EXEC && command) {
 781                         /* setenv will leak memory, use putenv/unsetenv/free */
 782                         char *s = xasprintf("%s=%s", "MDEV", node_name);
 783                         putenv(s);
 784                         dbg1("running: %s", command);
 785                         if (system(command) == -1)
 786                                 bb_perror_msg("can't run '%s'", command);
 787                         bb_unsetenv_and_free(s);
 788                 }
 789
 790                 if (operation == OP_remove && major >= -1) {
 791                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 792                                 if (aliaslink == '>') {
 793                                         dbg1("unlink: %s", device_name);
 794                                         unlink(device_name);
 795                                 }
 796                         }
 797                         dbg1("unlink: %s", node_name);
 798                         unlink(node_name);
 799                 }
 800
 801                 if (ENABLE_FEATURE_MDEV_RENAME)
 802                         free(alias);
 803
 804                 /* We found matching line.
 805                  * Stop unless it was prefixed with '-'
 806                  */
 807                 if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching)
 808                         break;
 809         } /* for (;;) */
 810 }
 811
 812 /* File callback for /sys/ traversal.
 813  * We act only on "/sys/.../dev" (pseudo)file
 814  */
 815 static int FAST_FUNC fileAction(const char *fileName,
 816                 struct stat *statbuf UNUSED_PARAM,
 817                 void *userData,
 818                 int depth UNUSED_PARAM)
 819 {
 820         size_t len = strlen(fileName) - 4; /* can't underflow */
 821         char *path = userData;  /* char array[PATH_MAX + SCRATCH_SIZE] */
 822         char subsys[PATH_MAX];
 823         int res;
 824
 825         /* Is it a ".../dev" file? (len check is for paranoid reasons) */
 826         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX - 32)
 827                 return FALSE; /* not .../dev */
 828
 829         strcpy(path, fileName);
 830         path[len] = '\0';
 831
 832         /* Read ".../subsystem" symlink in the same directory where ".../dev" is */
 833         strcpy(subsys, path);
 834         strcpy(subsys + len, "/subsystem");
 835         res = readlink(subsys, subsys, sizeof(subsys)-1);
 836         if (res > 0) {
 837                 subsys[res] = '\0';
 838                 free(G.subsystem);
 839                 if (G.subsys_env) {
 840                         bb_unsetenv_and_free(G.subsys_env);
 841                         G.subsys_env = NULL;
 842                 }
 843                 /* Set G.subsystem and $SUBSYSTEM from symlink's last component */
 844                 G.subsystem = strrchr(subsys, '/');
 845                 if (G.subsystem) {
 846                         G.subsystem = xstrdup(G.subsystem + 1);
 847                         G.subsys_env = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
 848                         putenv(G.subsys_env);
 849                 }
 850         }
 851
 852         make_device(/*DEVNAME:*/ NULL, path, OP_add);
 853
 854         return TRUE;
 855 }
 856
 857 /* Directory callback for /sys/ traversal */
 858 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 859                 struct stat *statbuf UNUSED_PARAM,
 860                 void *userData UNUSED_PARAM,
 861                 int depth)
 862 {
 863         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 864 }
 865
 866 /* For the full gory details, see linux/Documentation/firmware_class/README
 867  *
 868  * Firmware loading works like this:
 869  * - kernel sets FIRMWARE env var
 870  * - userspace checks /lib/firmware/$FIRMWARE
 871  * - userspace waits for /sys/$DEVPATH/loading to appear
 872  * - userspace writes "1" to /sys/$DEVPATH/loading
 873  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 874  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 875  * - kernel loads firmware into device
 876  */
 877 static void load_firmware(const char *firmware, const char *sysfs_path)
 878 {
 879         int cnt;
 880         int firmware_fd, loading_fd;
 881
 882         /* check for /lib/firmware/$FIRMWARE */
 883         firmware_fd = -1;
 884         if (chdir("/lib/firmware") == 0)
 885                 firmware_fd = open(firmware, O_RDONLY); /* can fail */
 886
 887         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 888         xchdir(sysfs_path);
 889         for (cnt = 0; cnt < 30; ++cnt) {
 890                 loading_fd = open("loading", O_WRONLY);
 891                 if (loading_fd >= 0)
 892                         goto loading;
 893                 sleep(1);
 894         }
 895         goto out;
 896
 897  loading:
 898         cnt = 0;
 899         if (firmware_fd >= 0) {
 900                 int data_fd;
 901
 902                 /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 903                 if (full_write(loading_fd, "1", 1) != 1)
 904                         goto out;
 905
 906                 /* load firmware into /sys/$DEVPATH/data */
 907                 data_fd = open("data", O_WRONLY);
 908                 if (data_fd < 0)
 909                         goto out;
 910                 cnt = bb_copyfd_eof(firmware_fd, data_fd);
 911                 if (ENABLE_FEATURE_CLEAN_UP)
 912                         close(data_fd);
 913         }
 914
 915         /* Tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading"
 916          * Note: we emit -1 also if firmware file wasn't found.
 917          * There are cases when otherwise kernel would wait for minutes
 918          * before timing out.
 919          */
 920         if (cnt > 0)
 921                 full_write(loading_fd, "0", 1);
 922         else
 923                 full_write(loading_fd, "-1", 2);
 924
 925  out:
 926         xchdir("/dev");
 927         if (ENABLE_FEATURE_CLEAN_UP) {
 928                 close(firmware_fd);
 929                 close(loading_fd);
 930         }
 931 }
 932
 933 static char *curtime(void)
 934 {
 935         struct timeval tv;
 936         gettimeofday(&tv, NULL);
 937         sprintf(
 938                 strftime_HHMMSS(G.timestr, sizeof(G.timestr), &tv.tv_sec),
 939                 ".%06u",
 940                 (unsigned)tv.tv_usec
 941         );
 942         return G.timestr;
 943 }
 944
 945 static void open_mdev_log(const char *seq, unsigned my_pid)
 946 {
 947         int logfd = open("mdev.log", O_WRONLY | O_APPEND);
 948         if (logfd >= 0) {
 949                 xmove_fd(logfd, STDERR_FILENO);
 950                 G.verbose = 2;
 951                 applet_name = xasprintf("%s[%s]", applet_name, seq ? seq : utoa(my_pid));
 952         }
 953 }
 954
 955 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 956  * If it does not match, earlier mdev is running
 957  * in parallel, and we need to wait.
 958  * Active mdev pokes us with SIGCHLD to check the new file.
 959  */
 960 static int
 961 wait_for_seqfile(unsigned expected_seq)
 962 {
 963         /* We time out after 2 sec */
 964         static const struct timespec ts = { 0, 32*1000*1000 };
 965         int timeout = 2000 / 32;
 966         int seq_fd = -1;
 967         int do_once = 1;
 968         sigset_t set_CHLD;
 969
 970         sigemptyset(&set_CHLD);
 971         sigaddset(&set_CHLD, SIGCHLD);
 972         sigprocmask(SIG_BLOCK, &set_CHLD, NULL);
 973
 974         for (;;) {
 975                 int seqlen;
 976                 char seqbuf[sizeof(long)*3 + 2];
 977                 unsigned seqbufnum;
 978
 979                 if (seq_fd < 0) {
 980                         seq_fd = open("mdev.seq", O_RDWR);
 981                         if (seq_fd < 0)
 982                                 break;
 983                         close_on_exec_on(seq_fd);
 984                 }
 985                 seqlen = pread(seq_fd, seqbuf, sizeof(seqbuf) - 1, 0);
 986                 if (seqlen < 0) {
 987                         close(seq_fd);
 988                         seq_fd = -1;
 989                         break;
 990                 }
 991                 seqbuf[seqlen] = '\0';
 992                 if (seqbuf[0] == '\n' || seqbuf[0] == '\0') {
 993                         /* seed file: write out seq ASAP */
 994                         xwrite_str(seq_fd, utoa(expected_seq));
 995                         xlseek(seq_fd, 0, SEEK_SET);
 996                         dbg2("first seq written");
 997                         break;
 998                 }
 999                 seqbufnum = atoll(seqbuf);
1000                 if (seqbufnum == expected_seq) {
1001                         /* correct idx */
1002                         break;
1003                 }
1004                 if (seqbufnum > expected_seq) {
1005                         /* a later mdev runs already (this was seen by users to happen) */
1006                         /* do not overwrite seqfile on exit */
1007                         close(seq_fd);
1008                         seq_fd = -1;
1009                         break;
1010                 }
1011                 if (do_once) {
1012                         dbg2("%s mdev.seq='%s', need '%u'", curtime(), seqbuf, expected_seq);
1013                         do_once = 0;
1014                 }
1015                 if (sigtimedwait(&set_CHLD, NULL, &ts) >= 0) {
1016                         dbg3("woken up");
1017                         continue; /* don't decrement timeout! */
1018                 }
1019                 if (--timeout == 0) {
1020                         dbg1("%s mdev.seq='%s'", "timed out", seqbuf);
1021                         break;
1022                 }
1023         }
1024         sigprocmask(SIG_UNBLOCK, &set_CHLD, NULL);
1025         return seq_fd;
1026 }
1027
1028 static void signal_mdevs(unsigned my_pid)
1029 {
1030         procps_status_t* p = NULL;
1031         while ((p = procps_scan(p, PSSCAN_ARGV0)) != NULL) {
1032                 if (p->pid != my_pid
1033                  && p->argv0
1034                  && strcmp(bb_basename(p->argv0), "mdev") == 0
1035                 ) {
1036                         kill(p->pid, SIGCHLD);
1037                 }
1038         }
1039 }
1040
1041 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1042 int mdev_main(int argc UNUSED_PARAM, char **argv)
1043 {
1044         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
1045
1046         INIT_G();
1047
1048 #if ENABLE_FEATURE_MDEV_CONF
1049         G.filename = "/etc/mdev.conf";
1050 #endif
1051
1052         /* We can be called as hotplug helper */
1053         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
1054         bb_sanitize_stdio();
1055
1056         /* Force the configuration file settings exactly */
1057         umask(0);
1058
1059         xchdir("/dev");
1060
1061         if (argv[1] && strcmp(argv[1], "-s") == 0) {
1062                 /*
1063                  * Scan: mdev -s
1064                  */
1065                 struct stat st;
1066
1067 #if ENABLE_FEATURE_MDEV_CONF
1068                 /* Same as xrealloc_vector(NULL, 4, 0): */
1069                 G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
1070 #endif
1071                 xstat("/", &st);
1072                 G.root_major = major(st.st_dev);
1073                 G.root_minor = minor(st.st_dev);
1074
1075                 putenv((char*)"ACTION=add");
1076
1077                 /* Create all devices from /sys/dev hierarchy */
1078                 recursive_action("/sys/dev",
1079                                  ACTION_RECURSE | ACTION_FOLLOWLINKS,
1080                                  fileAction, dirAction, temp, 0);
1081         } else {
1082                 char *fw;
1083                 char *seq;
1084                 char *action;
1085                 char *env_devname;
1086                 char *env_devpath;
1087                 unsigned my_pid;
1088                 unsigned seqnum = seqnum; /* for compiler */
1089                 int seq_fd;
1090                 smalluint op;
1091
1092                 /* Hotplug:
1093                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
1094                  * ACTION can be "add", "remove", "change"
1095                  * DEVPATH is like "/block/sda" or "/class/input/mice"
1096                  */
1097                 env_devname = getenv("DEVNAME"); /* can be NULL */
1098                 G.subsystem = getenv("SUBSYSTEM");
1099                 action = getenv("ACTION");
1100                 env_devpath = getenv("DEVPATH");
1101                 if (!action || !env_devpath /*|| !G.subsystem*/)
1102                         bb_show_usage();
1103                 fw = getenv("FIRMWARE");
1104                 seq = getenv("SEQNUM");
1105                 op = index_in_strings(keywords, action);
1106
1107                 my_pid = getpid();
1108                 open_mdev_log(seq, my_pid);
1109
1110                 seq_fd = -1;
1111                 if (seq) {
1112                         seqnum = atoll(seq);
1113                         seq_fd = wait_for_seqfile(seqnum);
1114                 }
1115
1116                 dbg1("%s "
1117                         "ACTION:%s SUBSYSTEM:%s DEVNAME:%s DEVPATH:%s"
1118                         "%s%s",
1119                         curtime(),
1120                         action, G.subsystem, env_devname, env_devpath,
1121                         fw ? " FW:" : "", fw ? fw : ""
1122                 );
1123
1124                 snprintf(temp, PATH_MAX, "/sys%s", env_devpath);
1125                 if (op == OP_remove) {
1126                         /* Ignoring "remove firmware". It was reported
1127                          * to happen and to cause erroneous deletion
1128                          * of device nodes. */
1129                         if (!fw)
1130                                 make_device(env_devname, temp, op);
1131                 }
1132                 else {
1133                         make_device(env_devname, temp, op);
1134                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
1135                                 if (op == OP_add && fw)
1136                                         load_firmware(fw, temp);
1137                         }
1138                 }
1139
1140                 dbg1("%s exiting", curtime());
1141                 if (seq_fd >= 0) {
1142                         xwrite_str(seq_fd, utoa(seqnum + 1));
1143                         signal_mdevs(my_pid);
1144                 }
1145         }
1146
1147         if (ENABLE_FEATURE_CLEAN_UP)
1148                 RELEASE_CONFIG_BUFFER(temp);
1149
1150         return EXIT_SUCCESS;
1151 }