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"
  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 firmwares"
  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 $SEQNUM variable. This prevents plug/unplug races.\n"
  95 //usage:       "To activate this feature, create empty /dev/mdev.seq at boot.\n"
  96 //usage:       "\n"
  97 //usage:       "If /dev/mdev.log file exists, debug log will be appended to it."
  98
  99 #include "libbb.h"
 100 #include "xregex.h"
 101
 102 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
 103  * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
 104  * contains "4:0\n". Directory name is taken as device name, path component
 105  * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
 106  * Then mdev creates the /dev/device_name node.
 107  * If /sys/class/.../dev file does not exist, mdev still may act
 108  * on this device: see "@|$|*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("60.123456")];
 287 } FIX_ALIASING;
 288 #define G (*(struct globals*)&bb_common_bufsiz1)
 289 #define INIT_G() do { \
 290         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.maj = -1;) \
 291         IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.mode = 0660;) \
 292 } while (0)
 293
 294
 295 /* Prevent infinite loops in /sys symlinks */
 296 #define MAX_SYSFS_DEPTH 3
 297
 298 /* We use additional bytes in make_device() */
 299 #define SCRATCH_SIZE 128
 300
 301 #if ENABLE_FEATURE_MDEV_CONF
 302
 303 static void make_default_cur_rule(void)
 304 {
 305         memset(&G.cur_rule, 0, sizeof(G.cur_rule));
 306         G.cur_rule.maj = -1; /* "not a @major,minor rule" */
 307         G.cur_rule.mode = 0660;
 308 }
 309
 310 static void clean_up_cur_rule(void)
 311 {
 312         struct envmatch *e;
 313
 314         free(G.cur_rule.envvar);
 315         free(G.cur_rule.ren_mov);
 316         if (G.cur_rule.regex_compiled)
 317                 regfree(&G.cur_rule.match);
 318         IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
 319         e = G.cur_rule.envmatch;
 320         while (e) {
 321                 free(e->envname);
 322                 regfree(&e->match);
 323                 e = e->next;
 324         }
 325         make_default_cur_rule();
 326 }
 327
 328 static char *parse_envmatch_pfx(char *val)
 329 {
 330         struct envmatch **nextp = &G.cur_rule.envmatch;
 331
 332         for (;;) {
 333                 struct envmatch *e;
 334                 char *semicolon;
 335                 char *eq = strchr(val, '=');
 336                 if (!eq /* || eq == val? */)
 337                         return val;
 338                 if (endofname(val) != eq)
 339                         return val;
 340                 semicolon = strchr(eq, ';');
 341                 if (!semicolon)
 342                         return val;
 343                 /* ENVVAR=regex;... */
 344                 *nextp = e = xzalloc(sizeof(*e));
 345                 nextp = &e->next;
 346                 e->envname = xstrndup(val, eq - val);
 347                 *semicolon = '\0';
 348                 xregcomp(&e->match, eq + 1, REG_EXTENDED);
 349                 *semicolon = ';';
 350                 val = semicolon + 1;
 351         }
 352 }
 353
 354 static void parse_next_rule(void)
 355 {
 356         /* Note: on entry, G.cur_rule is set to default */
 357         while (1) {
 358                 char *tokens[4];
 359                 char *val;
 360
 361                 /* No PARSE_EOL_COMMENTS, because command may contain '#' chars */
 362                 if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL & ~PARSE_EOL_COMMENTS))
 363                         break;
 364
 365                 /* Fields: [-]regex uid:gid mode [alias] [cmd] */
 366                 dbg3("token1:'%s'", tokens[1]);
 367
 368                 /* 1st field */
 369                 val = tokens[0];
 370                 G.cur_rule.keep_matching = ('-' == val[0]);
 371                 val += G.cur_rule.keep_matching; /* swallow leading dash */
 372                 val = parse_envmatch_pfx(val);
 373                 if (val[0] == '@') {
 374                         /* @major,minor[-minor2] */
 375                         /* (useful when name is ambiguous:
 376                          * "/sys/class/usb/lp0" and
 377                          * "/sys/class/printer/lp0")
 378                          */
 379                         int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
 380                         if (sc < 2 || G.cur_rule.maj < 0) {
 381                                 bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
 382                                 goto next_rule;
 383                         }
 384                         if (sc == 2)
 385                                 G.cur_rule.min1 = G.cur_rule.min0;
 386                 } else {
 387                         char *eq = strchr(val, '=');
 388                         if (val[0] == '$') {
 389                                 /* $ENVVAR=regex ... */
 390                                 val++;
 391                                 if (!eq) {
 392                                         bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
 393                                         goto next_rule;
 394                                 }
 395                                 G.cur_rule.envvar = xstrndup(val, eq - val);
 396                                 val = eq + 1;
 397                         }
 398                         xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
 399                         G.cur_rule.regex_compiled = 1;
 400                 }
 401
 402                 /* 2nd field: uid:gid - device ownership */
 403                 if (get_uidgid(&G.cur_rule.ugid, tokens[1], /*allow_numeric:*/ 1) == 0) {
 404                         bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
 405                         goto next_rule;
 406                 }
 407
 408                 /* 3rd field: mode - device permissions */
 409                 bb_parse_mode(tokens[2], &G.cur_rule.mode);
 410
 411                 /* 4th field (opt): ">|=alias" or "!" to not create the node */
 412                 val = tokens[3];
 413                 if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
 414                         char *s = skip_non_whitespace(val);
 415                         G.cur_rule.ren_mov = xstrndup(val, s - val);
 416                         val = skip_whitespace(s);
 417                 }
 418
 419                 if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
 420                         const char *s = "$@*";
 421                         const char *s2 = strchr(s, val[0]);
 422                         if (!s2) {
 423                                 bb_error_msg("bad line %u", G.parser->lineno);
 424                                 goto next_rule;
 425                         }
 426                         IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
 427                 }
 428
 429                 return;
 430  next_rule:
 431                 clean_up_cur_rule();
 432         } /* while (config_read) */
 433
 434         dbg3("config_close(G.parser)");
 435         config_close(G.parser);
 436         G.parser = NULL;
 437
 438         return;
 439 }
 440
 441 /* If mdev -s, we remember rules in G.rule_vec[].
 442  * Otherwise, there is no point in doing it, and we just
 443  * save only one parsed rule in G.cur_rule.
 444  */
 445 static const struct rule *next_rule(void)
 446 {
 447         struct rule *rule;
 448
 449         /* Open conf file if we didn't do it yet */
 450         if (!G.parser && G.filename) {
 451                 dbg3("config_open('%s')", G.filename);
 452                 G.parser = config_open2(G.filename, fopen_for_read);
 453                 G.filename = NULL;
 454         }
 455
 456         if (G.rule_vec) {
 457                 /* mdev -s */
 458                 /* Do we have rule parsed already? */
 459                 if (G.rule_vec[G.rule_idx]) {
 460                         dbg3("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 461                         return G.rule_vec[G.rule_idx++];
 462                 }
 463                 make_default_cur_rule();
 464         } else {
 465                 /* not mdev -s */
 466                 clean_up_cur_rule();
 467         }
 468
 469         /* Parse one more rule if file isn't fully read */
 470         rule = &G.cur_rule;
 471         if (G.parser) {
 472                 parse_next_rule();
 473                 if (G.rule_vec) { /* mdev -s */
 474                         rule = memcpy(xmalloc(sizeof(G.cur_rule)), &G.cur_rule, sizeof(G.cur_rule));
 475                         G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
 476                         G.rule_vec[G.rule_idx++] = rule;
 477                         dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 478                 }
 479         }
 480
 481         return rule;
 482 }
 483
 484 static int env_matches(struct envmatch *e)
 485 {
 486         while (e) {
 487                 int r;
 488                 char *val = getenv(e->envname);
 489                 if (!val)
 490                         return 0;
 491                 r = regexec(&e->match, val, /*size*/ 0, /*range[]*/ NULL, /*eflags*/ 0);
 492                 if (r != 0) /* no match */
 493                         return 0;
 494                 e = e->next;
 495         }
 496         return 1;
 497 }
 498
 499 #else
 500
 501 # define next_rule() (&G.cur_rule)
 502
 503 #endif
 504
 505 static void mkdir_recursive(char *name)
 506 {
 507         /* if name has many levels ("dir1/dir2"),
 508          * bb_make_directory() will create dir1 according to umask,
 509          * not according to its "mode" parameter.
 510          * Since we run with umask=0, need to temporarily switch it.
 511          */
 512         umask(022); /* "dir1" (if any) will be 0755 too */
 513         bb_make_directory(name, 0755, FILEUTILS_RECUR);
 514         umask(0);
 515 }
 516
 517 /* Builds an alias path.
 518  * This function potentionally reallocates the alias parameter.
 519  * Only used for ENABLE_FEATURE_MDEV_RENAME
 520  */
 521 static char *build_alias(char *alias, const char *device_name)
 522 {
 523         char *dest;
 524
 525         /* ">bar/": rename to bar/device_name */
 526         /* ">bar[/]baz": rename to bar[/]baz */
 527         dest = strrchr(alias, '/');
 528         if (dest) { /* ">bar/[baz]" ? */
 529                 *dest = '\0'; /* mkdir bar */
 530                 mkdir_recursive(alias);
 531                 *dest = '/';
 532                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 533                         dest = alias;
 534                         alias = concat_path_file(alias, device_name);
 535                         free(dest);
 536                 }
 537         }
 538
 539         return alias;
 540 }
 541
 542 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
 543  * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
 544  * after NUL, but we promise to not mangle (IOW: to restore NUL if needed)
 545  * path string.
 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 && strncmp(G.subsystem, "block", 5) == 0))
 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 /* File callback for /sys/ traversal */
 812 static int FAST_FUNC fileAction(const char *fileName,
 813                 struct stat *statbuf UNUSED_PARAM,
 814                 void *userData,
 815                 int depth UNUSED_PARAM)
 816 {
 817         size_t len = strlen(fileName) - 4; /* can't underflow */
 818         char *scratch = userData;
 819
 820         /* len check is for paranoid reasons */
 821         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 822                 return FALSE;
 823
 824         strcpy(scratch, fileName);
 825         scratch[len] = '\0';
 826         make_device(/*DEVNAME:*/ NULL, scratch, OP_add);
 827
 828         return TRUE;
 829 }
 830
 831 /* Directory callback for /sys/ traversal */
 832 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 833                 struct stat *statbuf UNUSED_PARAM,
 834                 void *userData UNUSED_PARAM,
 835                 int depth)
 836 {
 837         /* Extract device subsystem -- the name of the directory
 838          * under /sys/class/ */
 839         if (1 == depth) {
 840                 free(G.subsystem);
 841                 if (G.subsys_env) {
 842                         bb_unsetenv_and_free(G.subsys_env);
 843                         G.subsys_env = NULL;
 844                 }
 845                 G.subsystem = strrchr(fileName, '/');
 846                 if (G.subsystem) {
 847                         G.subsystem = xstrdup(G.subsystem + 1);
 848                         G.subsys_env = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
 849                         putenv(G.subsys_env);
 850                 }
 851         }
 852
 853         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 854 }
 855
 856 /* For the full gory details, see linux/Documentation/firmware_class/README
 857  *
 858  * Firmware loading works like this:
 859  * - kernel sets FIRMWARE env var
 860  * - userspace checks /lib/firmware/$FIRMWARE
 861  * - userspace waits for /sys/$DEVPATH/loading to appear
 862  * - userspace writes "1" to /sys/$DEVPATH/loading
 863  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 864  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 865  * - kernel loads firmware into device
 866  */
 867 static void load_firmware(const char *firmware, const char *sysfs_path)
 868 {
 869         int cnt;
 870         int firmware_fd, loading_fd;
 871
 872         /* check for /lib/firmware/$FIRMWARE */
 873         xchdir("/lib/firmware");
 874         firmware_fd = open(firmware, O_RDONLY); /* can fail */
 875
 876         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 877         xchdir(sysfs_path);
 878         for (cnt = 0; cnt < 30; ++cnt) {
 879                 loading_fd = open("loading", O_WRONLY);
 880                 if (loading_fd >= 0)
 881                         goto loading;
 882                 sleep(1);
 883         }
 884         goto out;
 885
 886  loading:
 887         cnt = 0;
 888         if (firmware_fd >= 0) {
 889                 int data_fd;
 890
 891                 /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 892                 if (full_write(loading_fd, "1", 1) != 1)
 893                         goto out;
 894
 895                 /* load firmware into /sys/$DEVPATH/data */
 896                 data_fd = open("data", O_WRONLY);
 897                 if (data_fd < 0)
 898                         goto out;
 899                 cnt = bb_copyfd_eof(firmware_fd, data_fd);
 900                 if (ENABLE_FEATURE_CLEAN_UP)
 901                         close(data_fd);
 902         }
 903
 904         /* Tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading"
 905          * Note: we emit -1 also if firmware file wasn't found.
 906          * There are cases when otherwise kernel would wait for minutes
 907          * before timing out.
 908          */
 909         if (cnt > 0)
 910                 full_write(loading_fd, "0", 1);
 911         else
 912                 full_write(loading_fd, "-1", 2);
 913
 914  out:
 915         xchdir("/dev");
 916         if (ENABLE_FEATURE_CLEAN_UP) {
 917                 close(firmware_fd);
 918                 close(loading_fd);
 919         }
 920 }
 921
 922 static char *curtime(void)
 923 {
 924         struct timeval tv;
 925         gettimeofday(&tv, NULL);
 926         sprintf(G.timestr, "%u.%06u", (unsigned)tv.tv_sec % 60, (unsigned)tv.tv_usec);
 927         return G.timestr;
 928 }
 929
 930 static void open_mdev_log(const char *seq, unsigned my_pid)
 931 {
 932         int logfd = open("mdev.log", O_WRONLY | O_APPEND);
 933         if (logfd >= 0) {
 934                 xmove_fd(logfd, STDERR_FILENO);
 935                 G.verbose = 2;
 936                 applet_name = xasprintf("%s[%s]", applet_name, seq ? seq : utoa(my_pid));
 937         }
 938 }
 939
 940 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 941  * If it does not match, earlier mdev is running
 942  * in parallel, and we need to wait.
 943  * Active mdev pokes us with SIGCHLD to check the new file.
 944  */
 945 static int
 946 wait_for_seqfile(const char *seq)
 947 {
 948         /* We time out after 2 sec */
 949         static const struct timespec ts = { 0, 32*1000*1000 };
 950         int timeout = 2000 / 32;
 951         int seq_fd = -1;
 952         int do_once = 1;
 953         sigset_t set_CHLD;
 954
 955         sigemptyset(&set_CHLD);
 956         sigaddset(&set_CHLD, SIGCHLD);
 957         sigprocmask(SIG_BLOCK, &set_CHLD, NULL);
 958
 959         for (;;) {
 960                 int seqlen;
 961                 char seqbuf[sizeof(int)*3 + 2];
 962
 963                 if (seq_fd < 0) {
 964                         seq_fd = open("mdev.seq", O_RDWR);
 965                         if (seq_fd < 0)
 966                                 break;
 967                 }
 968                 seqlen = pread(seq_fd, seqbuf, sizeof(seqbuf) - 1, 0);
 969                 if (seqlen < 0) {
 970                         close(seq_fd);
 971                         seq_fd = -1;
 972                         break;
 973                 }
 974                 seqbuf[seqlen] = '\0';
 975                 if (seqbuf[0] == '\n') {
 976                         /* seed file: write out seq ASAP */
 977                         xwrite_str(seq_fd, seq);
 978                         xlseek(seq_fd, 0, SEEK_SET);
 979                         dbg2("first seq written");
 980                         break;
 981                 }
 982                 if (strcmp(seq, seqbuf) == 0) {
 983                         /* correct idx */
 984                         break;
 985                 }
 986                 if (do_once) {
 987                         dbg2("%s waiting for '%s'", curtime(), seqbuf);
 988                         do_once = 0;
 989                 }
 990                 if (sigtimedwait(&set_CHLD, NULL, &ts) >= 0) {
 991                         dbg3("woken up");
 992                         continue; /* don't decrement timeout! */
 993                 }
 994                 if (--timeout == 0) {
 995                         dbg1("%s waiting for '%s'", "timed out", seqbuf);
 996                         break;
 997                 }
 998         }
 999         sigprocmask(SIG_UNBLOCK, &set_CHLD, NULL);
1000         return seq_fd;
1001 }
1002
1003 static void signal_mdevs(unsigned my_pid)
1004 {
1005         procps_status_t* p = NULL;
1006         while ((p = procps_scan(p, PSSCAN_ARGV0)) != NULL) {
1007                 if (p->pid != my_pid
1008                  && p->argv0
1009                  && strcmp(bb_basename(p->argv0), "mdev") == 0
1010                 ) {
1011                         kill(p->pid, SIGCHLD);
1012                 }
1013         }
1014 }
1015
1016 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1017 int mdev_main(int argc UNUSED_PARAM, char **argv)
1018 {
1019         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
1020
1021         INIT_G();
1022
1023 #if ENABLE_FEATURE_MDEV_CONF
1024         G.filename = "/etc/mdev.conf";
1025 #endif
1026
1027         /* We can be called as hotplug helper */
1028         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
1029         bb_sanitize_stdio();
1030
1031         /* Force the configuration file settings exactly */
1032         umask(0);
1033
1034         xchdir("/dev");
1035
1036         if (argv[1] && strcmp(argv[1], "-s") == 0) {
1037                 /*
1038                  * Scan: mdev -s
1039                  */
1040                 struct stat st;
1041
1042 #if ENABLE_FEATURE_MDEV_CONF
1043                 /* Same as xrealloc_vector(NULL, 4, 0): */
1044                 G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
1045 #endif
1046                 xstat("/", &st);
1047                 G.root_major = major(st.st_dev);
1048                 G.root_minor = minor(st.st_dev);
1049
1050                 putenv((char*)"ACTION=add");
1051
1052                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
1053                  * /sys/block/loop* (for example) are symlinks to dirs,
1054                  * not real directories.
1055                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
1056                  * but we can't enforce that on users)
1057                  */
1058                 if (access("/sys/class/block", F_OK) != 0) {
1059                         /* Scan obsolete /sys/block only if /sys/class/block
1060                          * doesn't exist. Otherwise we'll have dupes.
1061                          * Also, do not complain if it doesn't exist.
1062                          * Some people configure kernel to have no blockdevs.
1063                          */
1064                         recursive_action("/sys/block",
1065                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
1066                                 fileAction, dirAction, temp, 0);
1067                 }
1068                 recursive_action("/sys/class",
1069                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
1070                         fileAction, dirAction, temp, 0);
1071         } else {
1072                 char *fw;
1073                 char *seq;
1074                 char *action;
1075                 char *env_devname;
1076                 char *env_devpath;
1077                 unsigned my_pid;
1078                 int seq_fd;
1079                 smalluint op;
1080
1081                 /* Hotplug:
1082                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
1083                  * ACTION can be "add", "remove", "change"
1084                  * DEVPATH is like "/block/sda" or "/class/input/mice"
1085                  */
1086                 env_devname = getenv("DEVNAME"); /* can be NULL */
1087                 G.subsystem = getenv("SUBSYSTEM");
1088                 action = getenv("ACTION");
1089                 env_devpath = getenv("DEVPATH");
1090                 if (!action || !env_devpath /*|| !G.subsystem*/)
1091                         bb_show_usage();
1092                 fw = getenv("FIRMWARE");
1093                 seq = getenv("SEQNUM");
1094                 op = index_in_strings(keywords, action);
1095
1096                 my_pid = getpid();
1097                 open_mdev_log(seq, my_pid);
1098
1099                 seq_fd = seq ? wait_for_seqfile(seq) : -1;
1100
1101                 dbg1("%s "
1102                         "ACTION:%s SUBSYSTEM:%s DEVNAME:%s DEVPATH:%s"
1103                         "%s%s",
1104                         curtime(),
1105                         action, G.subsystem, env_devname, env_devpath,
1106                         fw ? " FW:" : "", fw ? fw : ""
1107                 );
1108
1109                 snprintf(temp, PATH_MAX, "/sys%s", env_devpath);
1110                 if (op == OP_remove) {
1111                         /* Ignoring "remove firmware". It was reported
1112                          * to happen and to cause erroneous deletion
1113                          * of device nodes. */
1114                         if (!fw)
1115                                 make_device(env_devname, temp, op);
1116                 }
1117                 else {
1118                         make_device(env_devname, temp, op);
1119                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
1120                                 if (op == OP_add && fw)
1121                                         load_firmware(fw, temp);
1122                         }
1123                 }
1124
1125                 dbg1("%s exiting", curtime());
1126                 if (seq_fd >= 0) {
1127                         xwrite_str(seq_fd, utoa(xatou(seq) + 1));
1128                         signal_mdevs(my_pid);
1129                 }
1130         }
1131
1132         if (ENABLE_FEATURE_CLEAN_UP)
1133                 RELEASE_CONFIG_BUFFER(temp);
1134
1135         return EXIT_SUCCESS;
1136 }