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 //config:config MDEV
  11 //config:       bool "mdev (17 kb)"
  12 //config:       default y
  13 //config:       select PLATFORM_LINUX
  14 //config:       help
  15 //config:       mdev is a mini-udev implementation for dynamically creating device
  16 //config:       nodes in the /dev directory.
  17 //config:
  18 //config:       For more information, please see docs/mdev.txt
  19 //config:
  20 //config:config FEATURE_MDEV_CONF
  21 //config:       bool "Support /etc/mdev.conf"
  22 //config:       default y
  23 //config:       depends on MDEV
  24 //config:       help
  25 //config:       Add support for the mdev config file to control ownership and
  26 //config:       permissions of the device nodes.
  27 //config:
  28 //config:       For more information, please see docs/mdev.txt
  29 //config:
  30 //config:config FEATURE_MDEV_RENAME
  31 //config:       bool "Support subdirs/symlinks"
  32 //config:       default y
  33 //config:       depends on FEATURE_MDEV_CONF
  34 //config:       help
  35 //config:       Add support for renaming devices and creating symlinks.
  36 //config:
  37 //config:       For more information, please see docs/mdev.txt
  38 //config:
  39 //config:config FEATURE_MDEV_RENAME_REGEXP
  40 //config:       bool "Support regular expressions substitutions when renaming device"
  41 //config:       default y
  42 //config:       depends on FEATURE_MDEV_RENAME
  43 //config:       help
  44 //config:       Add support for regular expressions substitutions when renaming
  45 //config:       device.
  46 //config:
  47 //config:config FEATURE_MDEV_EXEC
  48 //config:       bool "Support command execution at device addition/removal"
  49 //config:       default y
  50 //config:       depends on FEATURE_MDEV_CONF
  51 //config:       help
  52 //config:       This adds support for an optional field to /etc/mdev.conf for
  53 //config:       executing commands when devices are created/removed.
  54 //config:
  55 //config:       For more information, please see docs/mdev.txt
  56 //config:
  57 //config:config FEATURE_MDEV_LOAD_FIRMWARE
  58 //config:       bool "Support loading of firmware"
  59 //config:       default y
  60 //config:       depends on MDEV
  61 //config:       help
  62 //config:       Some devices need to load firmware before they can be usable.
  63 //config:
  64 //config:       These devices will request userspace look up the files in
  65 //config:       /lib/firmware/ and if it exists, send it to the kernel for
  66 //config:       loading into the hardware.
  67
  68 //applet:IF_MDEV(APPLET(mdev, BB_DIR_SBIN, BB_SUID_DROP))
  69
  70 //kbuild:lib-$(CONFIG_MDEV) += mdev.o
  71
  72 //usage:#define mdev_trivial_usage
  73 //usage:       "[-s]"
  74 //usage:#define mdev_full_usage "\n\n"
  75 //usage:       "mdev -s is to be run during boot to scan /sys and populate /dev.\n"
  76 //usage:       "\n"
  77 //usage:       "Bare mdev is a kernel hotplug helper. To activate it:\n"
  78 //usage:       "        echo /sbin/mdev >/proc/sys/kernel/hotplug\n"
  79 //usage:        IF_FEATURE_MDEV_CONF(
  80 //usage:       "\n"
  81 //usage:       "It uses /etc/mdev.conf with lines\n"
  82 //usage:       "        [-][ENV=regex;]...DEVNAME UID:GID PERM"
  83 //usage:                        IF_FEATURE_MDEV_RENAME(" [>|=PATH]|[!]")
  84 //usage:                        IF_FEATURE_MDEV_EXEC(" [@|$|*PROG]")
  85 //usage:       "\n"
  86 //usage:       "where DEVNAME is device name regex, @major,minor[-minor2], or\n"
  87 //usage:       "environment variable regex. A common use of the latter is\n"
  88 //usage:       "to load modules for hotplugged devices:\n"
  89 //usage:       "        $MODALIAS=.* 0:0 660 @modprobe \"$MODALIAS\"\n"
  90 //usage:        )
  91 //usage:       "\n"
  92 //usage:       "If /dev/mdev.seq file exists, mdev will wait for its value\n"
  93 //usage:       "to match $SEQNUM variable. This prevents plug/unplug races.\n"
  94 //usage:       "To activate this feature, create empty /dev/mdev.seq at boot.\n"
  95 //usage:       "\n"
  96 //usage:       "If /dev/mdev.log file exists, debug log will be appended to it."
  97
  98 #include "libbb.h"
  99 #include "common_bufsiz.h"
 100 #include "xregex.h"
 101
 102 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
 103  * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
 104  * contains "4:0\n". Directory name is taken as device name, path component
 105  * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
 106  * Then mdev creates the /dev/device_name node.
 107  * If /sys/class/.../dev file does not exist, mdev still may act
 108  * on this device: see "@|$|*command args..." parameter in config file.
 109  *
 110  * mdev w/o parameters is called as hotplug helper. It takes device
 111  * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
 112  * maj,min from "/sys/$DEVPATH/dev" and also examines
 113  * $ACTION ("add"/"delete") and $FIRMWARE.
 114  *
 115  * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
 116  * (todo: explain "delete" and $FIRMWARE)
 117  *
 118  * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
 119  *
 120  * Leading minus in 1st field means "don't stop on this line", otherwise
 121  * search is stopped after the matching line is encountered.
 122  *
 123  * $envvar=regex format is useful for loading modules for hot-plugged devices
 124  * which do not have driver loaded yet. In this case /sys/class/.../dev
 125  * does not exist, but $MODALIAS is set to needed module's name
 126  * (actually, an alias to it) by kernel. This rule instructs mdev
 127  * to load the module and exit:
 128  *    $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
 129  * The kernel will generate another hotplug event when /sys/class/.../dev
 130  * file appears.
 131  *
 132  * When line matches, the device node is created, chmod'ed and chown'ed,
 133  * moved to path, and if >path, a symlink to moved node is created,
 134  * all this if /sys/class/.../dev exists.
 135  *    Examples:
 136  *    =loop/      - moves to /dev/loop
 137  *    >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
 138  *
 139  * Then "command args..." is executed (via sh -c 'command args...').
 140  * @:execute on creation, $:on deletion, *:on both.
 141  * This happens regardless of /sys/class/.../dev existence.
 142  */
 143
 144 /* Kernel's hotplug environment constantly changes.
 145  * Here are new cases I observed on 3.1.0:
 146  *
 147  * Case with $DEVNAME and $DEVICE, not just $DEVPATH:
 148  * ACTION=add
 149  * BUSNUM=001
 150  * DEVICE=/proc/bus/usb/001/003
 151  * DEVNAME=bus/usb/001/003
 152  * DEVNUM=003
 153  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5
 154  * DEVTYPE=usb_device
 155  * MAJOR=189
 156  * MINOR=2
 157  * PRODUCT=18d1/4e12/227
 158  * SUBSYSTEM=usb
 159  * TYPE=0/0/0
 160  *
 161  * Case with $DEVICE, but no $DEVNAME - apparenty, usb iface notification?
 162  * "Please load me a module" thing?
 163  * ACTION=add
 164  * DEVICE=/proc/bus/usb/001/003
 165  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0
 166  * DEVTYPE=usb_interface
 167  * INTERFACE=8/6/80
 168  * MODALIAS=usb:v18D1p4E12d0227dc00dsc00dp00ic08isc06ip50
 169  * PRODUCT=18d1/4e12/227
 170  * SUBSYSTEM=usb
 171  * TYPE=0/0/0
 172  *
 173  * ACTION=add
 174  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5
 175  * DEVTYPE=scsi_host
 176  * SUBSYSTEM=scsi
 177  *
 178  * ACTION=add
 179  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/scsi_host/host5
 180  * SUBSYSTEM=scsi_host
 181  *
 182  * ACTION=add
 183  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0
 184  * DEVTYPE=scsi_target
 185  * SUBSYSTEM=scsi
 186  *
 187  * Case with strange $MODALIAS:
 188  * ACTION=add
 189  * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0
 190  * DEVTYPE=scsi_device
 191  * MODALIAS=scsi:t-0x00
 192  * SUBSYSTEM=scsi
 193  *
 194  * ACTION=add
 195  * 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
 196  * SUBSYSTEM=scsi_disk
 197  *
 198  * ACTION=add
 199  * 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
 200  * SUBSYSTEM=scsi_device
 201  *
 202  * Case with explicit $MAJOR/$MINOR (no need to read /sys/$DEVPATH/dev?):
 203  * ACTION=add
 204  * DEVNAME=bsg/5:0:0:0
 205  * 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
 206  * MAJOR=253
 207  * MINOR=1
 208  * SUBSYSTEM=bsg
 209  *
 210  * ACTION=add
 211  * DEVPATH=/devices/virtual/bdi/8:16
 212  * SUBSYSTEM=bdi
 213  *
 214  * ACTION=add
 215  * DEVNAME=sdb
 216  * DEVPATH=/block/sdb
 217  * DEVTYPE=disk
 218  * MAJOR=8
 219  * MINOR=16
 220  * SUBSYSTEM=block
 221  *
 222  * Case with ACTION=change:
 223  * ACTION=change
 224  * DEVNAME=sdb
 225  * DEVPATH=/block/sdb
 226  * DEVTYPE=disk
 227  * DISK_MEDIA_CHANGE=1
 228  * MAJOR=8
 229  * MINOR=16
 230  * SUBSYSTEM=block
 231  */
 232
 233 #define DEBUG_LVL 2
 234
 235 #if DEBUG_LVL >= 1
 236 # define dbg1(...) do { if (G.verbose) bb_error_msg(__VA_ARGS__); } while(0)
 237 #else
 238 # define dbg1(...) ((void)0)
 239 #endif
 240 #if DEBUG_LVL >= 2
 241 # define dbg2(...) do { if (G.verbose >= 2) bb_error_msg(__VA_ARGS__); } while(0)
 242 #else
 243 # define dbg2(...) ((void)0)
 244 #endif
 245 #if DEBUG_LVL >= 3
 246 # define dbg3(...) do { if (G.verbose >= 3) bb_error_msg(__VA_ARGS__); } while(0)
 247 #else
 248 # define dbg3(...) ((void)0)
 249 #endif
 250
 251
 252 static const char keywords[] ALIGN1 = "add\0remove\0"; // "change\0"
 253 enum { OP_add, OP_remove };
 254
 255 struct envmatch {
 256         struct envmatch *next;
 257         char *envname;
 258         regex_t match;
 259 };
 260
 261 struct rule {
 262         bool keep_matching;
 263         bool regex_compiled;
 264         mode_t mode;
 265         int maj, min0, min1;
 266         struct bb_uidgid_t ugid;
 267         char *envvar;
 268         char *ren_mov;
 269         IF_FEATURE_MDEV_EXEC(char *r_cmd;)
 270         regex_t match;
 271         struct envmatch *envmatch;
 272 };
 273
 274 struct globals {
 275         int root_major, root_minor;
 276         smallint verbose;
 277         char *subsystem;
 278         char *subsys_env; /* for putenv("SUBSYSTEM=subsystem") */
 279 #if ENABLE_FEATURE_MDEV_CONF
 280         const char *filename;
 281         parser_t *parser;
 282         struct rule **rule_vec;
 283         unsigned rule_idx;
 284 #endif
 285         struct rule cur_rule;
 286         char timestr[sizeof("HH:MM:SS.123456")];
 287 } FIX_ALIASING;
 288 #define G (*(struct globals*)bb_common_bufsiz1)
 289 #define INIT_G() do { \
 290         setup_common_bufsiz(); \
 291         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.maj = -1;) \
 292         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.mode = 0660;) \
 293 } while (0)
 294
 295
 296 /* Prevent infinite loops in /sys symlinks */
 297 #define MAX_SYSFS_DEPTH 3
 298
 299 /* We use additional bytes in make_device() */
 300 #define SCRATCH_SIZE 128
 301
 302 #if ENABLE_FEATURE_MDEV_CONF
 303
 304 static void make_default_cur_rule(void)
 305 {
 306         memset(&G.cur_rule, 0, sizeof(G.cur_rule));
 307         G.cur_rule.maj = -1; /* "not a @major,minor rule" */
 308         G.cur_rule.mode = 0660;
 309 }
 310
 311 static void clean_up_cur_rule(void)
 312 {
 313         struct envmatch *e;
 314
 315         free(G.cur_rule.envvar);
 316         free(G.cur_rule.ren_mov);
 317         if (G.cur_rule.regex_compiled)
 318                 regfree(&G.cur_rule.match);
 319         IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
 320         e = G.cur_rule.envmatch;
 321         while (e) {
 322                 free(e->envname);
 323                 regfree(&e->match);
 324                 e = e->next;
 325         }
 326         make_default_cur_rule();
 327 }
 328
 329 static char *parse_envmatch_pfx(char *val)
 330 {
 331         struct envmatch **nextp = &G.cur_rule.envmatch;
 332
 333         for (;;) {
 334                 struct envmatch *e;
 335                 char *semicolon;
 336                 char *eq = strchr(val, '=');
 337                 if (!eq /* || eq == val? */)
 338                         return val;
 339                 if (endofname(val) != eq)
 340                         return val;
 341                 semicolon = strchr(eq, ';');
 342                 if (!semicolon)
 343                         return val;
 344                 /* ENVVAR=regex;... */
 345                 *nextp = e = xzalloc(sizeof(*e));
 346                 nextp = &e->next;
 347                 e->envname = xstrndup(val, eq - val);
 348                 *semicolon = '\0';
 349                 xregcomp(&e->match, eq + 1, REG_EXTENDED);
 350                 *semicolon = ';';
 351                 val = semicolon + 1;
 352         }
 353 }
 354
 355 static void parse_next_rule(void)
 356 {
 357         /* Note: on entry, G.cur_rule is set to default */
 358         while (1) {
 359                 char *tokens[4];
 360                 char *val;
 361
 362                 /* No PARSE_EOL_COMMENTS, because command may contain '#' chars */
 363                 if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL & ~PARSE_EOL_COMMENTS))
 364                         break;
 365
 366                 /* Fields: [-]regex uid:gid mode [alias] [cmd] */
 367                 dbg3("token1:'%s'", tokens[1]);
 368
 369                 /* 1st field */
 370                 val = tokens[0];
 371                 G.cur_rule.keep_matching = ('-' == val[0]);
 372                 val += G.cur_rule.keep_matching; /* swallow leading dash */
 373                 val = parse_envmatch_pfx(val);
 374                 if (val[0] == '@') {
 375                         /* @major,minor[-minor2] */
 376                         /* (useful when name is ambiguous:
 377                          * "/sys/class/usb/lp0" and
 378                          * "/sys/class/printer/lp0")
 379                          */
 380                         int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
 381                         if (sc < 2 || G.cur_rule.maj < 0) {
 382                                 bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
 383                                 goto next_rule;
 384                         }
 385                         if (sc == 2)
 386                                 G.cur_rule.min1 = G.cur_rule.min0;
 387                 } else {
 388                         char *eq = strchr(val, '=');
 389                         if (val[0] == '$') {
 390                                 /* $ENVVAR=regex ... */
 391                                 val++;
 392                                 if (!eq) {
 393                                         bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
 394                                         goto next_rule;
 395                                 }
 396                                 G.cur_rule.envvar = xstrndup(val, eq - val);
 397                                 val = eq + 1;
 398                         }
 399                         xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
 400                         G.cur_rule.regex_compiled = 1;
 401                 }
 402
 403                 /* 2nd field: uid:gid - device ownership */
 404                 if (get_uidgid(&G.cur_rule.ugid, tokens[1]) == 0) {
 405                         bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
 406                         goto next_rule;
 407                 }
 408
 409                 /* 3rd field: mode - device permissions */
 410                 G.cur_rule.mode = bb_parse_mode(tokens[2], G.cur_rule.mode);
 411
 412                 /* 4th field (opt): ">|=alias" or "!" to not create the node */
 413                 val = tokens[3];
 414                 if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
 415                         char *s = skip_non_whitespace(val);
 416                         G.cur_rule.ren_mov = xstrndup(val, s - val);
 417                         val = skip_whitespace(s);
 418                 }
 419
 420                 if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
 421                         const char *s = "$@*";
 422                         const char *s2 = strchr(s, val[0]);
 423                         if (!s2) {
 424                                 bb_error_msg("bad line %u", G.parser->lineno);
 425                                 goto next_rule;
 426                         }
 427                         IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
 428                 }
 429
 430                 return;
 431  next_rule:
 432                 clean_up_cur_rule();
 433         } /* while (config_read) */
 434
 435         dbg3("config_close(G.parser)");
 436         config_close(G.parser);
 437         G.parser = NULL;
 438
 439         return;
 440 }
 441
 442 /* If mdev -s, we remember rules in G.rule_vec[].
 443  * Otherwise, there is no point in doing it, and we just
 444  * save only one parsed rule in G.cur_rule.
 445  */
 446 static const struct rule *next_rule(void)
 447 {
 448         struct rule *rule;
 449
 450         /* Open conf file if we didn't do it yet */
 451         if (!G.parser && G.filename) {
 452                 dbg3("config_open('%s')", G.filename);
 453                 G.parser = config_open2(G.filename, fopen_for_read);
 454                 G.filename = NULL;
 455         }
 456
 457         if (G.rule_vec) {
 458                 /* mdev -s */
 459                 /* Do we have rule parsed already? */
 460                 if (G.rule_vec[G.rule_idx]) {
 461                         dbg3("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 462                         return G.rule_vec[G.rule_idx++];
 463                 }
 464                 make_default_cur_rule();
 465         } else {
 466                 /* not mdev -s */
 467                 clean_up_cur_rule();
 468         }
 469
 470         /* Parse one more rule if file isn't fully read */
 471         rule = &G.cur_rule;
 472         if (G.parser) {
 473                 parse_next_rule();
 474                 if (G.rule_vec) { /* mdev -s */
 475                         rule = xmemdup(&G.cur_rule, sizeof(G.cur_rule));
 476                         G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
 477                         G.rule_vec[G.rule_idx++] = rule;
 478                         dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 479                 }
 480         }
 481
 482         return rule;
 483 }
 484
 485 static int env_matches(struct envmatch *e)
 486 {
 487         while (e) {
 488                 int r;
 489                 char *val = getenv(e->envname);
 490                 if (!val)
 491                         return 0;
 492                 r = regexec(&e->match, val, /*size*/ 0, /*range[]*/ NULL, /*eflags*/ 0);
 493                 if (r != 0) /* no match */
 494                         return 0;
 495                 e = e->next;
 496         }
 497         return 1;
 498 }
 499
 500 #else
 501
 502 # define next_rule() (&G.cur_rule)
 503
 504 #endif
 505
 506 static void mkdir_recursive(char *name)
 507 {
 508         /* if name has many levels ("dir1/dir2"),
 509          * bb_make_directory() will create dir1 according to umask,
 510          * not according to its "mode" parameter.
 511          * Since we run with umask=0, need to temporarily switch it.
 512          */
 513         umask(022); /* "dir1" (if any) will be 0755 too */
 514         bb_make_directory(name, 0755, FILEUTILS_RECUR);
 515         umask(0);
 516 }
 517
 518 /* Builds an alias path.
 519  * This function potentionally reallocates the alias parameter.
 520  * Only used for ENABLE_FEATURE_MDEV_RENAME
 521  */
 522 static char *build_alias(char *alias, const char *device_name)
 523 {
 524         char *dest;
 525
 526         /* ">bar/": rename to bar/device_name */
 527         /* ">bar[/]baz": rename to bar[/]baz */
 528         dest = strrchr(alias, '/');
 529         if (dest) { /* ">bar/[baz]" ? */
 530                 *dest = '\0'; /* mkdir bar */
 531                 mkdir_recursive(alias);
 532                 *dest = '/';
 533                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 534                         dest = alias;
 535                         alias = concat_path_file(alias, device_name);
 536                         free(dest);
 537                 }
 538         }
 539
 540         return alias;
 541 }
 542
 543 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
 544  * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
 545  * after NUL, but we promise to not mangle it (IOW: to restore NUL if needed).
 546  * NB2: "mdev -s" may call us many times, do not leak memory/fds!
 547  *
 548  * device_name = $DEVNAME (may be NULL)
 549  * path        = /sys/$DEVPATH
 550  */
 551 static void make_device(char *device_name, char *path, int operation)
 552 {
 553         int major, minor, type, len;
 554         char *path_end = path + strlen(path);
 555
 556         /* Try to read major/minor string.  Note that the kernel puts \n after
 557          * the data, so we don't need to worry about null terminating the string
 558          * because sscanf() will stop at the first nondigit, which \n is.
 559          * We also depend on path having writeable space after it.
 560          */
 561         major = -1;
 562         if (operation == OP_add) {
 563                 strcpy(path_end, "/dev");
 564                 len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
 565                 *path_end = '\0';
 566                 if (len < 1) {
 567                         if (!ENABLE_FEATURE_MDEV_EXEC)
 568                                 return;
 569                         /* no "dev" file, but we can still run scripts
 570                          * based on device name */
 571                 } else if (sscanf(path_end + 1, "%u:%u", &major, &minor) == 2) {
 572                         dbg1("dev %u,%u", major, minor);
 573                 } else {
 574                         major = -1;
 575                 }
 576         }
 577         /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
 578
 579         /* Determine device name */
 580         if (!device_name) {
 581                 /*
 582                  * There was no $DEVNAME envvar (for example, mdev -s never has).
 583                  * But it is very useful: it contains the *path*, not only basename,
 584                  * Thankfully, uevent file has it.
 585                  * Example of .../sound/card0/controlC0/uevent file on Linux-3.7.7:
 586                  * MAJOR=116
 587                  * MINOR=7
 588                  * DEVNAME=snd/controlC0
 589                  */
 590                 strcpy(path_end, "/uevent");
 591                 len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
 592                 if (len < 0)
 593                         len = 0;
 594                 *path_end = '\0';
 595                 path_end[1 + len] = '\0';
 596                 device_name = strstr(path_end + 1, "\nDEVNAME=");
 597                 if (device_name) {
 598                         device_name += sizeof("\nDEVNAME=")-1;
 599                         strchrnul(device_name, '\n')[0] = '\0';
 600                 } else {
 601                         /* Fall back to just basename */
 602                         device_name = (char*) bb_basename(path);
 603                 }
 604         }
 605         /* Determine device type */
 606         /*
 607          * http://kernel.org/doc/pending/hotplug.txt says that only
 608          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 609          * But since 2.6.25 block devices are also in /sys/class/block.
 610          * We use strstr("/block/") to forestall future surprises.
 611          */
 612         type = S_IFCHR;
 613         if (strstr(path, "/block/") || (G.subsystem && is_prefixed_with(G.subsystem, "block")))
 614                 type = S_IFBLK;
 615
 616 #if ENABLE_FEATURE_MDEV_CONF
 617         G.rule_idx = 0; /* restart from the beginning (think mdev -s) */
 618 #endif
 619         for (;;) {
 620                 const char *str_to_match;
 621                 regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 622                 char *command;
 623                 char *alias;
 624                 char aliaslink = aliaslink; /* for compiler */
 625                 char *node_name;
 626                 const struct rule *rule;
 627
 628                 str_to_match = device_name;
 629
 630                 rule = next_rule();
 631
 632 #if ENABLE_FEATURE_MDEV_CONF
 633                 if (!env_matches(rule->envmatch))
 634                         continue;
 635                 if (rule->maj >= 0) {  /* @maj,min rule */
 636                         if (major != rule->maj)
 637                                 continue;
 638                         if (minor < rule->min0 || minor > rule->min1)
 639                                 continue;
 640                         memset(off, 0, sizeof(off));
 641                         goto rule_matches;
 642                 }
 643                 if (rule->envvar) { /* $envvar=regex rule */
 644                         str_to_match = getenv(rule->envvar);
 645                         dbg3("getenv('%s'):'%s'", rule->envvar, str_to_match);
 646                         if (!str_to_match)
 647                                 continue;
 648                 }
 649                 /* else: str_to_match = device_name */
 650
 651                 if (rule->regex_compiled) {
 652                         int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0);
 653                         dbg3("regex_match for '%s':%d", str_to_match, regex_match);
 654                         //bb_error_msg("matches:");
 655                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 656                         //      if (off[i].rm_so < 0) continue;
 657                         //      bb_error_msg("match %d: '%.*s'\n", i,
 658                         //              (int)(off[i].rm_eo - off[i].rm_so),
 659                         //              device_name + off[i].rm_so);
 660                         //}
 661
 662                         if (regex_match != 0
 663                         /* regexec returns whole pattern as "range" 0 */
 664                          || off[0].rm_so != 0
 665                          || (int)off[0].rm_eo != (int)strlen(str_to_match)
 666                         ) {
 667                                 continue; /* this rule doesn't match */
 668                         }
 669                 }
 670                 /* else: it's final implicit "match-all" rule */
 671  rule_matches:
 672                 dbg2("rule matched, line %d", G.parser ? G.parser->lineno : -1);
 673 #endif
 674                 /* Build alias name */
 675                 alias = NULL;
 676                 if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) {
 677                         aliaslink = rule->ren_mov[0];
 678                         if (aliaslink == '!') {
 679                                 /* "!": suppress node creation/deletion */
 680                                 major = -2;
 681                         }
 682                         else if (aliaslink == '>' || aliaslink == '=') {
 683                                 if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
 684                                         char *s;
 685                                         char *p;
 686                                         unsigned n;
 687
 688                                         /* substitute %1..9 with off[1..9], if any */
 689                                         n = 0;
 690                                         s = rule->ren_mov;
 691                                         while (*s)
 692                                                 if (*s++ == '%')
 693                                                         n++;
 694
 695                                         p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match));
 696                                         s = rule->ren_mov + 1;
 697                                         while (*s) {
 698                                                 *p = *s;
 699                                                 if ('%' == *s) {
 700                                                         unsigned i = (s[1] - '0');
 701                                                         if (i <= 9 && off[i].rm_so >= 0) {
 702                                                                 n = off[i].rm_eo - off[i].rm_so;
 703                                                                 strncpy(p, str_to_match + off[i].rm_so, n);
 704                                                                 p += n - 1;
 705                                                                 s++;
 706                                                         }
 707                                                 }
 708                                                 p++;
 709                                                 s++;
 710                                         }
 711                                 } else {
 712                                         alias = xstrdup(rule->ren_mov + 1);
 713                                 }
 714                         }
 715                 }
 716                 dbg3("alias:'%s'", alias);
 717
 718                 command = NULL;
 719                 IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;)
 720                 if (command) {
 721                         /* Are we running this command now?
 722                          * Run @cmd on create, $cmd on delete, *cmd on any
 723                          */
 724                         if ((command[0] == '@' && operation == OP_add)
 725                          || (command[0] == '$' && operation == OP_remove)
 726                          || (command[0] == '*')
 727                         ) {
 728                                 command++;
 729                         } else {
 730                                 command = NULL;
 731                         }
 732                 }
 733                 dbg3("command:'%s'", command);
 734
 735                 /* "Execute" the line we found */
 736                 node_name = device_name;
 737                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 738                         node_name = alias = build_alias(alias, device_name);
 739                         dbg3("alias2:'%s'", alias);
 740                 }
 741
 742                 if (operation == OP_add && major >= 0) {
 743                         char *slash = strrchr(node_name, '/');
 744                         if (slash) {
 745                                 *slash = '\0';
 746                                 mkdir_recursive(node_name);
 747                                 *slash = '/';
 748                         }
 749                         if (ENABLE_FEATURE_MDEV_CONF) {
 750                                 dbg1("mknod %s (%d,%d) %o"
 751                                         " %u:%u",
 752                                         node_name, major, minor, rule->mode | type,
 753                                         rule->ugid.uid, rule->ugid.gid
 754                                 );
 755                         } else {
 756                                 dbg1("mknod %s (%d,%d) %o",
 757                                         node_name, major, minor, rule->mode | type
 758                                 );
 759                         }
 760                         if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST)
 761                                 bb_perror_msg("can't create '%s'", node_name);
 762                         if (ENABLE_FEATURE_MDEV_CONF) {
 763                                 chmod(node_name, rule->mode);
 764                                 chown(node_name, rule->ugid.uid, rule->ugid.gid);
 765                         }
 766                         if (major == G.root_major && minor == G.root_minor)
 767                                 symlink(node_name, "root");
 768                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 769                                 if (aliaslink == '>') {
 770 //TODO: on devtmpfs, device_name already exists and symlink() fails.
 771 //End result is that instead of symlink, we have two nodes.
 772 //What should be done?
 773                                         dbg1("symlink: %s", device_name);
 774                                         symlink(node_name, device_name);
 775                                 }
 776                         }
 777                 }
 778
 779                 if (ENABLE_FEATURE_MDEV_EXEC && command) {
 780                         /* setenv will leak memory, use putenv/unsetenv/free */
 781                         char *s = xasprintf("%s=%s", "MDEV", node_name);
 782                         putenv(s);
 783                         dbg1("running: %s", command);
 784                         if (system(command) == -1)
 785                                 bb_perror_msg("can't run '%s'", command);
 786                         bb_unsetenv_and_free(s);
 787                 }
 788
 789                 if (operation == OP_remove && major >= -1) {
 790                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 791                                 if (aliaslink == '>') {
 792                                         dbg1("unlink: %s", device_name);
 793                                         unlink(device_name);
 794                                 }
 795                         }
 796                         dbg1("unlink: %s", node_name);
 797                         unlink(node_name);
 798                 }
 799
 800                 if (ENABLE_FEATURE_MDEV_RENAME)
 801                         free(alias);
 802
 803                 /* We found matching line.
 804                  * Stop unless it was prefixed with '-'
 805                  */
 806                 if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching)
 807                         break;
 808         } /* for (;;) */
 809 }
 810
 811 static ssize_t readlink2(char *buf, size_t bufsize)
 812 {
 813         // Grr... gcc 8.1.1:
 814         // "passing argument 2 to restrict-qualified parameter aliases with argument 1"
 815         // dance around that...
 816         char *obuf FIX_ALIASING;
 817         obuf = buf;
 818         return readlink(buf, obuf, bufsize);
 819 }
 820
 821 /* File callback for /sys/ traversal.
 822  * We act only on "/sys/.../dev" (pseudo)file
 823  */
 824 static int FAST_FUNC fileAction(const char *fileName,
 825                 struct stat *statbuf UNUSED_PARAM,
 826                 void *userData,
 827                 int depth UNUSED_PARAM)
 828 {
 829         size_t len = strlen(fileName) - 4; /* can't underflow */
 830         char *path = userData;  /* char array[PATH_MAX + SCRATCH_SIZE] */
 831         char subsys[PATH_MAX];
 832         int res;
 833
 834         /* Is it a ".../dev" file? (len check is for paranoid reasons) */
 835         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX - 32)
 836                 return FALSE; /* not .../dev */
 837
 838         strcpy(path, fileName);
 839         path[len] = '\0';
 840
 841         /* Read ".../subsystem" symlink in the same directory where ".../dev" is */
 842         strcpy(subsys, path);
 843         strcpy(subsys + len, "/subsystem");
 844         res = readlink2(subsys, sizeof(subsys)-1);
 845         if (res > 0) {
 846                 subsys[res] = '\0';
 847                 free(G.subsystem);
 848                 if (G.subsys_env) {
 849                         bb_unsetenv_and_free(G.subsys_env);
 850                         G.subsys_env = NULL;
 851                 }
 852                 /* Set G.subsystem and $SUBSYSTEM from symlink's last component */
 853                 G.subsystem = strrchr(subsys, '/');
 854                 if (G.subsystem) {
 855                         G.subsystem = xstrdup(G.subsystem + 1);
 856                         G.subsys_env = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
 857                         putenv(G.subsys_env);
 858                 }
 859         }
 860
 861         make_device(/*DEVNAME:*/ NULL, path, OP_add);
 862
 863         return TRUE;
 864 }
 865
 866 /* Directory callback for /sys/ traversal */
 867 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 868                 struct stat *statbuf UNUSED_PARAM,
 869                 void *userData UNUSED_PARAM,
 870                 int depth)
 871 {
 872         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 873 }
 874
 875 /* For the full gory details, see linux/Documentation/firmware_class/README
 876  *
 877  * Firmware loading works like this:
 878  * - kernel sets FIRMWARE env var
 879  * - userspace checks /lib/firmware/$FIRMWARE
 880  * - userspace waits for /sys/$DEVPATH/loading to appear
 881  * - userspace writes "1" to /sys/$DEVPATH/loading
 882  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 883  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 884  * - kernel loads firmware into device
 885  */
 886 static void load_firmware(const char *firmware, const char *sysfs_path)
 887 {
 888         int cnt;
 889         int firmware_fd, loading_fd;
 890
 891         /* check for /lib/firmware/$FIRMWARE */
 892         firmware_fd = -1;
 893         if (chdir("/lib/firmware") == 0)
 894                 firmware_fd = open(firmware, O_RDONLY); /* can fail */
 895
 896         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 897         xchdir(sysfs_path);
 898         for (cnt = 0; cnt < 30; ++cnt) {
 899                 loading_fd = open("loading", O_WRONLY);
 900                 if (loading_fd >= 0)
 901                         goto loading;
 902                 sleep(1);
 903         }
 904         goto out;
 905
 906  loading:
 907         cnt = 0;
 908         if (firmware_fd >= 0) {
 909                 int data_fd;
 910
 911                 /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 912                 if (full_write(loading_fd, "1", 1) != 1)
 913                         goto out;
 914
 915                 /* load firmware into /sys/$DEVPATH/data */
 916                 data_fd = open("data", O_WRONLY);
 917                 if (data_fd < 0)
 918                         goto out;
 919                 cnt = bb_copyfd_eof(firmware_fd, data_fd);
 920                 if (ENABLE_FEATURE_CLEAN_UP)
 921                         close(data_fd);
 922         }
 923
 924         /* Tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading"
 925          * Note: we emit -1 also if firmware file wasn't found.
 926          * There are cases when otherwise kernel would wait for minutes
 927          * before timing out.
 928          */
 929         if (cnt > 0)
 930                 full_write(loading_fd, "0", 1);
 931         else
 932                 full_write(loading_fd, "-1", 2);
 933
 934  out:
 935         xchdir("/dev");
 936         if (ENABLE_FEATURE_CLEAN_UP) {
 937                 close(firmware_fd);
 938                 close(loading_fd);
 939         }
 940 }
 941
 942 static char *curtime(void)
 943 {
 944         struct timeval tv;
 945         gettimeofday(&tv, NULL);
 946         sprintf(
 947                 strftime_HHMMSS(G.timestr, sizeof(G.timestr), &tv.tv_sec),
 948                 ".%06u",
 949                 (unsigned)tv.tv_usec
 950         );
 951         return G.timestr;
 952 }
 953
 954 static void open_mdev_log(const char *seq, unsigned my_pid)
 955 {
 956         int logfd = open("mdev.log", O_WRONLY | O_APPEND);
 957         if (logfd >= 0) {
 958                 xmove_fd(logfd, STDERR_FILENO);
 959                 G.verbose = 2;
 960                 applet_name = xasprintf("%s[%s]", applet_name, seq ? seq : utoa(my_pid));
 961         }
 962 }
 963
 964 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 965  * If it does not match, earlier mdev is running
 966  * in parallel, and we need to wait.
 967  * Active mdev pokes us with SIGCHLD to check the new file.
 968  */
 969 static int
 970 wait_for_seqfile(unsigned expected_seq)
 971 {
 972         /* We time out after 2 sec */
 973         static const struct timespec ts = { 0, 32*1000*1000 };
 974         int timeout = 2000 / 32;
 975         int seq_fd = -1;
 976         int do_once = 1;
 977         sigset_t set_CHLD;
 978
 979         sigemptyset(&set_CHLD);
 980         sigaddset(&set_CHLD, SIGCHLD);
 981         sigprocmask(SIG_BLOCK, &set_CHLD, NULL);
 982
 983         for (;;) {
 984                 int seqlen;
 985                 char seqbuf[sizeof(long)*3 + 2];
 986                 unsigned seqbufnum;
 987
 988                 if (seq_fd < 0) {
 989                         seq_fd = open("mdev.seq", O_RDWR);
 990                         if (seq_fd < 0)
 991                                 break;
 992                         close_on_exec_on(seq_fd);
 993                 }
 994                 seqlen = pread(seq_fd, seqbuf, sizeof(seqbuf) - 1, 0);
 995                 if (seqlen < 0) {
 996                         close(seq_fd);
 997                         seq_fd = -1;
 998                         break;
 999                 }
1000                 seqbuf[seqlen] = '\0';
1001                 if (seqbuf[0] == '\n' || seqbuf[0] == '\0') {
1002                         /* seed file: write out seq ASAP */
1003                         xwrite_str(seq_fd, utoa(expected_seq));
1004                         xlseek(seq_fd, 0, SEEK_SET);
1005                         dbg2("first seq written");
1006                         break;
1007                 }
1008                 seqbufnum = atoll(seqbuf);
1009                 if (seqbufnum == expected_seq) {
1010                         /* correct idx */
1011                         break;
1012                 }
1013                 if (seqbufnum > expected_seq) {
1014                         /* a later mdev runs already (this was seen by users to happen) */
1015                         /* do not overwrite seqfile on exit */
1016                         close(seq_fd);
1017                         seq_fd = -1;
1018                         break;
1019                 }
1020                 if (do_once) {
1021                         dbg2("%s mdev.seq='%s', need '%u'", curtime(), seqbuf, expected_seq);
1022                         do_once = 0;
1023                 }
1024                 if (sigtimedwait(&set_CHLD, NULL, &ts) >= 0) {
1025                         dbg3("woken up");
1026                         continue; /* don't decrement timeout! */
1027                 }
1028                 if (--timeout == 0) {
1029                         dbg1("%s mdev.seq='%s'", "timed out", seqbuf);
1030                         break;
1031                 }
1032         }
1033         sigprocmask(SIG_UNBLOCK, &set_CHLD, NULL);
1034         return seq_fd;
1035 }
1036
1037 static void signal_mdevs(unsigned my_pid)
1038 {
1039         procps_status_t* p = NULL;
1040         while ((p = procps_scan(p, PSSCAN_ARGV0)) != NULL) {
1041                 if (p->pid != my_pid
1042                  && p->argv0
1043                  && strcmp(bb_basename(p->argv0), "mdev") == 0
1044                 ) {
1045                         kill(p->pid, SIGCHLD);
1046                 }
1047         }
1048 }
1049
1050 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1051 int mdev_main(int argc UNUSED_PARAM, char **argv)
1052 {
1053         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
1054
1055         INIT_G();
1056
1057 #if ENABLE_FEATURE_MDEV_CONF
1058         G.filename = "/etc/mdev.conf";
1059 #endif
1060
1061         /* We can be called as hotplug helper */
1062         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
1063         bb_sanitize_stdio();
1064
1065         /* Force the configuration file settings exactly */
1066         umask(0);
1067
1068         xchdir("/dev");
1069
1070         if (argv[1] && strcmp(argv[1], "-s") == 0) {
1071                 /*
1072                  * Scan: mdev -s
1073                  */
1074                 struct stat st;
1075
1076 #if ENABLE_FEATURE_MDEV_CONF
1077                 /* Same as xrealloc_vector(NULL, 4, 0): */
1078                 G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
1079 #endif
1080                 xstat("/", &st);
1081                 G.root_major = major(st.st_dev);
1082                 G.root_minor = minor(st.st_dev);
1083
1084                 putenv((char*)"ACTION=add");
1085
1086                 /* Create all devices from /sys/dev hierarchy */
1087                 recursive_action("/sys/dev",
1088                                  ACTION_RECURSE | ACTION_FOLLOWLINKS,
1089                                  fileAction, dirAction, temp, 0);
1090         } else {
1091                 char *fw;
1092                 char *seq;
1093                 char *action;
1094                 char *env_devname;
1095                 char *env_devpath;
1096                 unsigned my_pid;
1097                 unsigned seqnum = seqnum; /* for compiler */
1098                 int seq_fd;
1099                 smalluint op;
1100
1101                 /* Hotplug:
1102                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
1103                  * ACTION can be "add", "remove", "change"
1104                  * DEVPATH is like "/block/sda" or "/class/input/mice"
1105                  */
1106                 env_devname = getenv("DEVNAME"); /* can be NULL */
1107                 G.subsystem = getenv("SUBSYSTEM");
1108                 action = getenv("ACTION");
1109                 env_devpath = getenv("DEVPATH");
1110                 if (!action || !env_devpath /*|| !G.subsystem*/)
1111                         bb_show_usage();
1112                 fw = getenv("FIRMWARE");
1113                 seq = getenv("SEQNUM");
1114                 op = index_in_strings(keywords, action);
1115
1116                 my_pid = getpid();
1117                 open_mdev_log(seq, my_pid);
1118
1119                 seq_fd = -1;
1120                 if (seq) {
1121                         seqnum = atoll(seq);
1122                         seq_fd = wait_for_seqfile(seqnum);
1123                 }
1124
1125                 dbg1("%s "
1126                         "ACTION:%s SUBSYSTEM:%s DEVNAME:%s DEVPATH:%s"
1127                         "%s%s",
1128                         curtime(),
1129                         action, G.subsystem, env_devname, env_devpath,
1130                         fw ? " FW:" : "", fw ? fw : ""
1131                 );
1132
1133                 snprintf(temp, PATH_MAX, "/sys%s", env_devpath);
1134                 if (op == OP_remove) {
1135                         /* Ignoring "remove firmware". It was reported
1136                          * to happen and to cause erroneous deletion
1137                          * of device nodes. */
1138                         if (!fw)
1139                                 make_device(env_devname, temp, op);
1140                 }
1141                 else {
1142                         make_device(env_devname, temp, op);
1143                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
1144                                 if (op == OP_add && fw)
1145                                         load_firmware(fw, temp);
1146                         }
1147                 }
1148
1149                 dbg1("%s exiting", curtime());
1150                 if (seq_fd >= 0) {
1151                         xwrite_str(seq_fd, utoa(seqnum + 1));
1152                         signal_mdevs(my_pid);
1153                 }
1154         }
1155
1156         if (ENABLE_FEATURE_CLEAN_UP)
1157                 RELEASE_CONFIG_BUFFER(temp);
1158
1159         return EXIT_SUCCESS;
1160 }