/* vi: set sw=4 ts=4: */ /* * mdev - Mini udev for busybox * * Copyright 2005 Rob Landley <rob@landley.net> * Copyright 2005 Frank Sorenson <frank@tuxrocks.com> * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config MDEV //config: bool "mdev (20 kb)" //config: default y //config: help //config: mdev is a mini-udev implementation for dynamically creating device //config: nodes in the /dev directory. //config: //config: For more information, please see docs/mdev.txt //config: //config:config FEATURE_MDEV_CONF //config: bool "Support /etc/mdev.conf" //config: default y //config: depends on MDEV //config: help //config: Add support for the mdev config file to control ownership and //config: permissions of the device nodes. //config: //config: For more information, please see docs/mdev.txt //config: //config:config FEATURE_MDEV_RENAME //config: bool "Support subdirs/symlinks" //config: default y //config: depends on FEATURE_MDEV_CONF //config: help //config: Add support for renaming devices and creating symlinks. //config: //config: For more information, please see docs/mdev.txt //config: //config:config FEATURE_MDEV_RENAME_REGEXP //config: bool "Support regular expressions substitutions when renaming device" //config: default y //config: depends on FEATURE_MDEV_RENAME //config: help //config: Add support for regular expressions substitutions when renaming //config: device. //config: //config:config FEATURE_MDEV_EXEC //config: bool "Support command execution at device addition/removal" //config: default y //config: depends on FEATURE_MDEV_CONF //config: help //config: This adds support for an optional field to /etc/mdev.conf for //config: executing commands when devices are created/removed. //config: //config: For more information, please see docs/mdev.txt //config: //config:config FEATURE_MDEV_LOAD_FIRMWARE //config: bool "Support loading of firmware" //config: default y //config: depends on MDEV //config: help //config: Some devices need to load firmware before they can be usable. //config: //config: These devices will request userspace look up the files in //config: /lib/firmware/ and if it exists, send it to the kernel for //config: loading into the hardware. //config: //config:config FEATURE_MDEV_DAEMON //config: bool "Support daemon mode" //config: default y //config: depends on MDEV //config: help //config: Adds the -d option to run mdev in daemon mode handling hotplug //config: events from the kernel like udev. If the system generates many //config: hotplug events this mode of operation will consume less //config: resources than registering mdev as hotplug helper or using the //config: uevent applet. //applet:IF_MDEV(APPLET(mdev, BB_DIR_SBIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_MDEV) += mdev.o //usage:#define mdev_trivial_usage //usage: "[-vS] " IF_FEATURE_MDEV_DAEMON("{ ") "[-s]" IF_FEATURE_MDEV_DAEMON(" | [-df] }") //usage:#define mdev_full_usage "\n\n" //usage: " -v Verbose\n" //usage: " -S Log to syslog too\n" //usage: " -s Scan /sys and populate /dev\n" //usage: IF_FEATURE_MDEV_DAEMON( //usage: " -d Daemon, listen on netlink\n" //usage: " -f Run in foreground\n" //usage: ) //usage: "\n" //usage: "Bare mdev is a kernel hotplug helper. To activate it:\n" //usage: " echo /sbin/mdev >/proc/sys/kernel/hotplug\n" //usage: IF_FEATURE_MDEV_CONF( //usage: "\n" //usage: "It uses /etc/mdev.conf with lines\n" //usage: " [-][ENV=regex;]...DEVNAME UID:GID PERM" //usage: IF_FEATURE_MDEV_RENAME(" [>|=PATH]|[!]") //usage: IF_FEATURE_MDEV_EXEC(" [@|$|*PROG]") //usage: "\n" //usage: "where DEVNAME is device name regex, @major,minor[-minor2], or\n" //usage: "environment variable regex. A common use of the latter is\n" //usage: "to load modules for hotplugged devices:\n" //usage: " $MODALIAS=.* 0:0 660 @modprobe \"$MODALIAS\"\n" //usage: ) //usage: "\n" //usage: "If /dev/mdev.seq file exists, mdev will wait for its value\n" //usage: "to match $SEQNUM variable. This prevents plug/unplug races.\n" //usage: "To activate this feature, create empty /dev/mdev.seq at boot.\n" //usage: "\n" //usage: "If /dev/mdev.log file exists, debug log will be appended to it." #include "libbb.h" #include "common_bufsiz.h" #include "xregex.h" #include <linux/netlink.h> #include <syslog.h> /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev * contains "4:0\n". Directory name is taken as device name, path component * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty". * Then mdev creates the /dev/device_name node. * If /sys/class/.../dev file does not exist, mdev still may act * on this device: see "@|$|*command args..." parameter in config file. * * mdev w/o parameters is called as hotplug helper. It takes device * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts * maj,min from "/sys/$DEVPATH/dev" and also examines * $ACTION ("add"/"delete") and $FIRMWARE. * * If action is "add", mdev creates /dev/device_name similarly to mdev -s. * (todo: explain "delete" and $FIRMWARE) * * If /etc/mdev.conf exists, it may modify /dev/device_name's properties. * * Leading minus in 1st field means "don't stop on this line", otherwise * search is stopped after the matching line is encountered. * * $envvar=regex format is useful for loading modules for hot-plugged devices * which do not have driver loaded yet. In this case /sys/class/.../dev * does not exist, but $MODALIAS is set to needed module's name * (actually, an alias to it) by kernel. This rule instructs mdev * to load the module and exit: * $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS" * The kernel will generate another hotplug event when /sys/class/.../dev * file appears. * * When line matches, the device node is created, chmod'ed and chown'ed, * moved to path, and if >path, a symlink to moved node is created, * all this if /sys/class/.../dev exists. * Examples: * =loop/ - moves to /dev/loop * >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink * * Then "command args..." is executed (via sh -c 'command args...'). * @:execute on creation, $:on deletion, *:on both. * This happens regardless of /sys/class/.../dev existence. */ /* Kernel's hotplug environment constantly changes. * Here are new cases I observed on 3.1.0: * * Case with $DEVNAME and $DEVICE, not just $DEVPATH: * ACTION=add * BUSNUM=001 * DEVICE=/proc/bus/usb/001/003 * DEVNAME=bus/usb/001/003 * DEVNUM=003 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5 * DEVTYPE=usb_device * MAJOR=189 * MINOR=2 * PRODUCT=18d1/4e12/227 * SUBSYSTEM=usb * TYPE=0/0/0 * * Case with $DEVICE, but no $DEVNAME - apparenty, usb iface notification? * "Please load me a module" thing? * ACTION=add * DEVICE=/proc/bus/usb/001/003 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0 * DEVTYPE=usb_interface * INTERFACE=8/6/80 * MODALIAS=usb:v18D1p4E12d0227dc00dsc00dp00ic08isc06ip50 * PRODUCT=18d1/4e12/227 * SUBSYSTEM=usb * TYPE=0/0/0 * * ACTION=add * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5 * DEVTYPE=scsi_host * SUBSYSTEM=scsi * * ACTION=add * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/scsi_host/host5 * SUBSYSTEM=scsi_host * * ACTION=add * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0 * DEVTYPE=scsi_target * SUBSYSTEM=scsi * * Case with strange $MODALIAS: * ACTION=add * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0 * DEVTYPE=scsi_device * MODALIAS=scsi:t-0x00 * SUBSYSTEM=scsi * * ACTION=add * 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 * SUBSYSTEM=scsi_disk * * ACTION=add * 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 * SUBSYSTEM=scsi_device * * Case with explicit $MAJOR/$MINOR (no need to read /sys/$DEVPATH/dev?): * ACTION=add * DEVNAME=bsg/5:0:0:0 * 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 * MAJOR=253 * MINOR=1 * SUBSYSTEM=bsg * * ACTION=add * DEVPATH=/devices/virtual/bdi/8:16 * SUBSYSTEM=bdi * * ACTION=add * DEVNAME=sdb * DEVPATH=/block/sdb * DEVTYPE=disk * MAJOR=8 * MINOR=16 * SUBSYSTEM=block * * Case with ACTION=change: * ACTION=change * DEVNAME=sdb * DEVPATH=/block/sdb * DEVTYPE=disk * DISK_MEDIA_CHANGE=1 * MAJOR=8 * MINOR=16 * SUBSYSTEM=block */ #define DEBUG_LVL 2 #if DEBUG_LVL >= 1 # define dbg1(...) do { if (G.verbose) bb_error_msg(__VA_ARGS__); } while(0) # define dbg1s(msg) do { if (G.verbose) bb_simple_error_msg(msg); } while(0) #else # define dbg1(...) ((void)0) # define dbg1s(msg) ((void)0) #endif #if DEBUG_LVL >= 2 # define dbg2(...) do { if (G.verbose >= 2) bb_error_msg(__VA_ARGS__); } while(0) # define dbg2s(msg) do { if (G.verbose >= 2) bb_simple_error_msg(msg); } while(0) #else # define dbg2(...) ((void)0) # define dbg2s(msg) ((void)0) #endif #if DEBUG_LVL >= 3 # define dbg3(...) do { if (G.verbose >= 3) bb_error_msg(__VA_ARGS__); } while(0) # define dbg3s(msg) do { if (G.verbose >= 3) bb_simple_error_msg(msg); } while(0) #else # define dbg3(...) ((void)0) # define dbg3s(msg) ((void)0) #endif static const char keywords[] ALIGN1 = "add\0remove\0"; // "change\0" enum { OP_add, OP_remove }; struct envmatch { struct envmatch *next; char *envname; regex_t match; }; struct rule { bool keep_matching; bool regex_compiled; mode_t mode; int maj, min0, min1; struct bb_uidgid_t ugid; char *envvar; char *ren_mov; IF_FEATURE_MDEV_EXEC(char *r_cmd;) regex_t match; struct envmatch *envmatch; }; struct globals { int root_major, root_minor; int verbose; char *subsystem; char *subsys_env; /* for putenv("SUBSYSTEM=subsystem") */ #if ENABLE_FEATURE_MDEV_CONF const char *filename; parser_t *parser; struct rule **rule_vec; unsigned rule_idx; #endif struct rule cur_rule; char timestr[sizeof("HH:MM:SS.123456")]; } FIX_ALIASING; #define G (*(struct globals*)bb_common_bufsiz1) #define INIT_G() do { \ setup_common_bufsiz(); \ IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.maj = -1;) \ IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.mode = 0660;) \ } while (0) /* Prevent infinite loops in /sys symlinks */ #define MAX_SYSFS_DEPTH 3 /* We use additional bytes in make_device() */ #define SCRATCH_SIZE 128 #if ENABLE_FEATURE_MDEV_CONF static void make_default_cur_rule(void) { memset(&G.cur_rule, 0, sizeof(G.cur_rule)); G.cur_rule.maj = -1; /* "not a @major,minor rule" */ G.cur_rule.mode = 0660; } static void clean_up_cur_rule(void) { struct envmatch *e; free(G.cur_rule.envvar); free(G.cur_rule.ren_mov); if (G.cur_rule.regex_compiled) regfree(&G.cur_rule.match); IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);) e = G.cur_rule.envmatch; while (e) { free(e->envname); regfree(&e->match); e = e->next; } make_default_cur_rule(); } static char *parse_envmatch_pfx(char *val) { struct envmatch **nextp = &G.cur_rule.envmatch; for (;;) { struct envmatch *e; char *semicolon; char *eq = strchr(val, '='); if (!eq /* || eq == val? */) return val; if (endofname(val) != eq) return val; semicolon = strchr(eq, ';'); if (!semicolon) return val; /* ENVVAR=regex;... */ *nextp = e = xzalloc(sizeof(*e)); nextp = &e->next; e->envname = xstrndup(val, eq - val); *semicolon = '\0'; xregcomp(&e->match, eq + 1, REG_EXTENDED); *semicolon = ';'; val = semicolon + 1; } } static void parse_next_rule(void) { /* Note: on entry, G.cur_rule is set to default */ while (1) { char *tokens[4]; char *val; /* No PARSE_EOL_COMMENTS, because command may contain '#' chars */ if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL & ~PARSE_EOL_COMMENTS)) break; /* Fields: [-]regex uid:gid mode [alias] [cmd] */ dbg3("token1:'%s'", tokens[1]); /* 1st field */ val = tokens[0]; G.cur_rule.keep_matching = ('-' == val[0]); val += G.cur_rule.keep_matching; /* swallow leading dash */ val = parse_envmatch_pfx(val); if (val[0] == '@') { /* @major,minor[-minor2] */ /* (useful when name is ambiguous: * "/sys/class/usb/lp0" and * "/sys/class/printer/lp0") */ int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1); if (sc < 2 || G.cur_rule.maj < 0) { bb_error_msg("bad @maj,min on line %d", G.parser->lineno); goto next_rule; } if (sc == 2) G.cur_rule.min1 = G.cur_rule.min0; } else { char *eq = strchr(val, '='); if (val[0] == '$') { /* $ENVVAR=regex ... */ val++; if (!eq) { bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno); goto next_rule; } G.cur_rule.envvar = xstrndup(val, eq - val); val = eq + 1; } xregcomp(&G.cur_rule.match, val, REG_EXTENDED); G.cur_rule.regex_compiled = 1; } /* 2nd field: uid:gid - device ownership */ if (get_uidgid(&G.cur_rule.ugid, tokens[1]) == 0) { bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno); goto next_rule; } /* 3rd field: mode - device permissions */ G.cur_rule.mode = bb_parse_mode(tokens[2], G.cur_rule.mode); /* 4th field (opt): ">|=alias" or "!" to not create the node */ val = tokens[3]; if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) { char *s = skip_non_whitespace(val); G.cur_rule.ren_mov = xstrndup(val, s - val); val = skip_whitespace(s); } if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) { const char *s = "$@*"; const char *s2 = strchr(s, val[0]); if (!s2) { bb_error_msg("bad line %u", G.parser->lineno); goto next_rule; } IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);) } return; next_rule: clean_up_cur_rule(); } /* while (config_read) */ dbg3("config_close(G.parser)"); config_close(G.parser); G.parser = NULL; return; } /* If mdev -s, we remember rules in G.rule_vec[]. * Otherwise, there is no point in doing it, and we just * save only one parsed rule in G.cur_rule. */ static const struct rule *next_rule(void) { struct rule *rule; /* Open conf file if we didn't do it yet */ if (!G.parser && G.filename) { dbg3("config_open('%s')", G.filename); G.parser = config_open2(G.filename, fopen_for_read); G.filename = NULL; } if (G.rule_vec) { /* mdev -s */ /* Do we have rule parsed already? */ if (G.rule_vec[G.rule_idx]) { dbg3("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]); return G.rule_vec[G.rule_idx++]; } make_default_cur_rule(); } else { /* not mdev -s */ clean_up_cur_rule(); } /* Parse one more rule if file isn't fully read */ rule = &G.cur_rule; if (G.parser) { parse_next_rule(); if (G.rule_vec) { /* mdev -s */ rule = xmemdup(&G.cur_rule, sizeof(G.cur_rule)); G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx); G.rule_vec[G.rule_idx++] = rule; dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]); } } return rule; } static int env_matches(struct envmatch *e) { while (e) { int r; char *val = getenv(e->envname); if (!val) return 0; r = regexec(&e->match, val, /*size*/ 0, /*range[]*/ NULL, /*eflags*/ 0); if (r != 0) /* no match */ return 0; e = e->next; } return 1; } #else # define next_rule() (&G.cur_rule) #endif static void mkdir_recursive(char *name) { /* if name has many levels ("dir1/dir2"), * bb_make_directory() will create dir1 according to umask, * not according to its "mode" parameter. * Since we run with umask=0, need to temporarily switch it. */ umask(022); /* "dir1" (if any) will be 0755 too */ bb_make_directory(name, 0755, FILEUTILS_RECUR); umask(0); } /* Builds an alias path. * This function potentionally reallocates the alias parameter. * Only used for ENABLE_FEATURE_MDEV_RENAME */ static char *build_alias(char *alias, const char *device_name) { char *dest; /* ">bar/": rename to bar/device_name */ /* ">bar[/]baz": rename to bar[/]baz */ dest = strrchr(alias, '/'); if (dest) { /* ">bar/[baz]" ? */ *dest = '\0'; /* mkdir bar */ mkdir_recursive(alias); *dest = '/'; if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */ dest = alias; alias = concat_path_file(alias, device_name); free(dest); } } return alias; } /* mknod in /dev based on a path like "/sys/block/hda/hda1" * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes * after NUL, but we promise to not mangle it (IOW: to restore NUL if needed). * NB2: "mdev -s" may call us many times, do not leak memory/fds! * * device_name = $DEVNAME (may be NULL) * path = /sys/$DEVPATH */ static void make_device(char *device_name, char *path, int operation) { int major, minor, type, len; char *path_end = path + strlen(path); /* Try to read major/minor string. Note that the kernel puts \n after * the data, so we don't need to worry about null terminating the string * because sscanf() will stop at the first nondigit, which \n is. * We also depend on path having writeable space after it. */ major = -1; if (operation == OP_add) { strcpy(path_end, "/dev"); len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1); *path_end = '\0'; if (len < 1) { if (!ENABLE_FEATURE_MDEV_EXEC) return; /* no "dev" file, but we can still run scripts * based on device name */ } else if (sscanf(path_end + 1, "%u:%u", &major, &minor) == 2) { dbg1("dev %u,%u", major, minor); } else { major = -1; } } /* else: for delete, -1 still deletes the node, but < -1 suppresses that */ /* Determine device name */ if (!device_name) { /* * There was no $DEVNAME envvar (for example, mdev -s never has). * But it is very useful: it contains the *path*, not only basename, * Thankfully, uevent file has it. * Example of .../sound/card0/controlC0/uevent file on Linux-3.7.7: * MAJOR=116 * MINOR=7 * DEVNAME=snd/controlC0 */ strcpy(path_end, "/uevent"); len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1); if (len < 0) len = 0; *path_end = '\0'; path_end[1 + len] = '\0'; device_name = strstr(path_end + 1, "\nDEVNAME="); if (device_name) { device_name += sizeof("\nDEVNAME=")-1; strchrnul(device_name, '\n')[0] = '\0'; } else { /* Fall back to just basename */ device_name = (char*) bb_basename(path); } } /* Determine device type */ /* * http://kernel.org/doc/pending/hotplug.txt says that only * "/sys/block/..." is for block devices. "/sys/bus" etc is not. * But since 2.6.25 block devices are also in /sys/class/block. * We use strstr("/block/") to forestall future surprises. */ type = S_IFCHR; if (strstr(path, "/block/") || (G.subsystem && is_prefixed_with(G.subsystem, "block"))) type = S_IFBLK; #if ENABLE_FEATURE_MDEV_CONF G.rule_idx = 0; /* restart from the beginning (think mdev -s) */ #endif for (;;) { const char *str_to_match; regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP]; char *command; char *alias; char aliaslink = aliaslink; /* for compiler */ char *node_name; const struct rule *rule; str_to_match = device_name; rule = next_rule(); #if ENABLE_FEATURE_MDEV_CONF if (!env_matches(rule->envmatch)) continue; if (rule->maj >= 0) { /* @maj,min rule */ if (major != rule->maj) continue; if (minor < rule->min0 || minor > rule->min1) continue; memset(off, 0, sizeof(off)); goto rule_matches; } if (rule->envvar) { /* $envvar=regex rule */ str_to_match = getenv(rule->envvar); dbg3("getenv('%s'):'%s'", rule->envvar, str_to_match); if (!str_to_match) continue; } /* else: str_to_match = device_name */ if (rule->regex_compiled) { int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0); dbg3("regex_match for '%s':%d", str_to_match, regex_match); //bb_error_msg("matches:"); //for (int i = 0; i < ARRAY_SIZE(off); i++) { // if (off[i].rm_so < 0) continue; // bb_error_msg("match %d: '%.*s'\n", i, // (int)(off[i].rm_eo - off[i].rm_so), // device_name + off[i].rm_so); //} if (regex_match != 0 /* regexec returns whole pattern as "range" 0 */ || off[0].rm_so != 0 || (int)off[0].rm_eo != (int)strlen(str_to_match) ) { continue; /* this rule doesn't match */ } } /* else: it's final implicit "match-all" rule */ rule_matches: dbg2("rule matched, line %d", G.parser ? G.parser->lineno : -1); #endif /* Build alias name */ alias = NULL; if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) { aliaslink = rule->ren_mov[0]; if (aliaslink == '!') { /* "!": suppress node creation/deletion */ major = -2; } else if (aliaslink == '>' || aliaslink == '=') { if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) { char *s; char *p; unsigned n; /* substitute %1..9 with off[1..9], if any */ n = 0; s = rule->ren_mov; while (*s) if (*s++ == '%') n++; p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match)); s = rule->ren_mov + 1; while (*s) { *p = *s; if ('%' == *s) { unsigned i = (s[1] - '0'); if (i <= 9 && off[i].rm_so >= 0) { n = off[i].rm_eo - off[i].rm_so; strncpy(p, str_to_match + off[i].rm_so, n); p += n - 1; s++; } } p++; s++; } } else { alias = xstrdup(rule->ren_mov + 1); } } } dbg3("alias:'%s'", alias); command = NULL; IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;) if (command) { /* Are we running this command now? * Run @cmd on create, $cmd on delete, *cmd on any */ if ((command[0] == '@' && operation == OP_add) || (command[0] == '$' && operation == OP_remove) || (command[0] == '*') ) { command++; } else { command = NULL; } } dbg3("command:'%s'", command); /* "Execute" the line we found */ node_name = device_name; if (ENABLE_FEATURE_MDEV_RENAME && alias) { node_name = alias = build_alias(alias, device_name); dbg3("alias2:'%s'", alias); } if (operation == OP_add && major >= 0) { char *slash = strrchr(node_name, '/'); if (slash) { *slash = '\0'; mkdir_recursive(node_name); *slash = '/'; } if (ENABLE_FEATURE_MDEV_CONF) { dbg1("mknod %s (%d,%d) %o" " %u:%u", node_name, major, minor, rule->mode | type, rule->ugid.uid, rule->ugid.gid ); } else { dbg1("mknod %s (%d,%d) %o", node_name, major, minor, rule->mode | type ); } if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST) bb_perror_msg("can't create '%s'", node_name); if (ENABLE_FEATURE_MDEV_CONF) { chmod(node_name, rule->mode); chown(node_name, rule->ugid.uid, rule->ugid.gid); } if (major == G.root_major && minor == G.root_minor) symlink(node_name, "root"); if (ENABLE_FEATURE_MDEV_RENAME && alias) { if (aliaslink == '>') { //TODO: on devtmpfs, device_name already exists and symlink() fails. //End result is that instead of symlink, we have two nodes. //What should be done? dbg1("symlink: %s", device_name); symlink(node_name, device_name); } } } if (ENABLE_FEATURE_MDEV_EXEC && command) { /* setenv will leak memory, use putenv/unsetenv/free */ char *s = xasprintf("%s=%s", "MDEV", node_name); putenv(s); dbg1("running: %s", command); if (system(command) == -1) bb_perror_msg("can't run '%s'", command); bb_unsetenv_and_free(s); } if (operation == OP_remove && major >= -1) { if (ENABLE_FEATURE_MDEV_RENAME && alias) { if (aliaslink == '>') { dbg1("unlink: %s", device_name); unlink(device_name); } } dbg1("unlink: %s", node_name); unlink(node_name); } if (ENABLE_FEATURE_MDEV_RENAME) free(alias); /* We found matching line. * Stop unless it was prefixed with '-' */ if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching) break; } /* for (;;) */ } static ssize_t readlink2(char *buf, size_t bufsize) { // Grr... gcc 8.1.1: // "passing argument 2 to restrict-qualified parameter aliases with argument 1" // dance around that... char *obuf FIX_ALIASING; obuf = buf; return readlink(buf, obuf, bufsize); } /* File callback for /sys/ traversal. * We act only on "/sys/.../dev" (pseudo)file */ static int FAST_FUNC fileAction(struct recursive_state *state, const char *fileName, struct stat *statbuf UNUSED_PARAM) { size_t len = strlen(fileName) - 4; /* can't underflow */ char *path = state->userData; /* char array[PATH_MAX + SCRATCH_SIZE] */ char subsys[PATH_MAX]; int res; /* Is it a ".../dev" file? (len check is for paranoid reasons) */ if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX - 32) return FALSE; /* not .../dev */ strcpy(path, fileName); path[len] = '\0'; /* Read ".../subsystem" symlink in the same directory where ".../dev" is */ strcpy(subsys, path); strcpy(subsys + len, "/subsystem"); res = readlink2(subsys, sizeof(subsys)-1); if (res > 0) { subsys[res] = '\0'; free(G.subsystem); if (G.subsys_env) { bb_unsetenv_and_free(G.subsys_env); G.subsys_env = NULL; } /* Set G.subsystem and $SUBSYSTEM from symlink's last component */ G.subsystem = strrchr(subsys, '/'); if (G.subsystem) { G.subsystem = xstrdup(G.subsystem + 1); G.subsys_env = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem); putenv(G.subsys_env); } } make_device(/*DEVNAME:*/ NULL, path, OP_add); return TRUE; } /* Directory callback for /sys/ traversal */ static int FAST_FUNC dirAction(struct recursive_state *state, const char *fileName UNUSED_PARAM, struct stat *statbuf UNUSED_PARAM) { return (state->depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE); } /* For the full gory details, see linux/Documentation/firmware_class/README * * Firmware loading works like this: * - kernel sets FIRMWARE env var * - userspace checks /lib/firmware/$FIRMWARE * - userspace waits for /sys/$DEVPATH/loading to appear * - userspace writes "1" to /sys/$DEVPATH/loading * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading * - kernel loads firmware into device */ static void load_firmware(const char *firmware, const char *sysfs_path) { int cnt; int firmware_fd, loading_fd; /* check for /lib/firmware/$FIRMWARE */ firmware_fd = -1; if (chdir("/lib/firmware") == 0) firmware_fd = open(firmware, O_RDONLY); /* can fail */ /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */ xchdir(sysfs_path); for (cnt = 0; cnt < 30; ++cnt) { loading_fd = open("loading", O_WRONLY); if (loading_fd >= 0) goto loading; sleep1(); } goto out; loading: cnt = 0; if (firmware_fd >= 0) { int data_fd; /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */ if (full_write(loading_fd, "1", 1) != 1) goto out; /* load firmware into /sys/$DEVPATH/data */ data_fd = open("data", O_WRONLY); if (data_fd < 0) goto out; cnt = bb_copyfd_eof(firmware_fd, data_fd); if (ENABLE_FEATURE_CLEAN_UP) close(data_fd); } /* Tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" * Note: we emit -1 also if firmware file wasn't found. * There are cases when otherwise kernel would wait for minutes * before timing out. */ if (cnt > 0) full_write(loading_fd, "0", 1); else full_write(loading_fd, "-1", 2); out: xchdir("/dev"); if (ENABLE_FEATURE_CLEAN_UP) { close(firmware_fd); close(loading_fd); } } static char *curtime(void) { struct timeval tv; xgettimeofday(&tv); sprintf( strftime_HHMMSS(G.timestr, sizeof(G.timestr), &tv.tv_sec), ".%06u", (unsigned)tv.tv_usec ); return G.timestr; } static void open_mdev_log(const char *seq, unsigned my_pid) { int logfd = open("mdev.log", O_WRONLY | O_APPEND); if (logfd >= 0) { xmove_fd(logfd, STDERR_FILENO); G.verbose = 2; applet_name = xasprintf("%s[%s]", applet_name, seq ? seq : utoa(my_pid)); } } /* If it exists, does /dev/mdev.seq match $SEQNUM? * If it does not match, earlier mdev is running * in parallel, and we need to wait. * Active mdev pokes us with SIGCHLD to check the new file. */ static int wait_for_seqfile(unsigned expected_seq) { /* We time out after 2 sec */ static const struct timespec ts = { 0, 32*1000*1000 }; int timeout = 2000 / 32; int seq_fd = -1; int do_once = 1; sigset_t set_CHLD; sigemptyset(&set_CHLD); sigaddset(&set_CHLD, SIGCHLD); sigprocmask(SIG_BLOCK, &set_CHLD, NULL); for (;;) { int seqlen; char seqbuf[sizeof(long)*3 + 2]; unsigned seqbufnum; if (seq_fd < 0) { seq_fd = open("mdev.seq", O_RDWR); if (seq_fd < 0) break; close_on_exec_on(seq_fd); } seqlen = pread(seq_fd, seqbuf, sizeof(seqbuf) - 1, 0); if (seqlen < 0) { close(seq_fd); seq_fd = -1; break; } seqbuf[seqlen] = '\0'; if (seqbuf[0] == '\n' || seqbuf[0] == '\0') { /* seed file: write out seq ASAP */ xwrite_str(seq_fd, utoa(expected_seq)); xlseek(seq_fd, 0, SEEK_SET); dbg2s("first seq written"); break; } seqbufnum = atoll(seqbuf); if (seqbufnum == expected_seq) { /* correct idx */ break; } if (seqbufnum > expected_seq) { /* a later mdev runs already (this was seen by users to happen) */ /* do not overwrite seqfile on exit */ close(seq_fd); seq_fd = -1; break; } if (do_once) { dbg2("%s mdev.seq='%s', need '%u'", curtime(), seqbuf, expected_seq); do_once = 0; } if (sigtimedwait(&set_CHLD, NULL, &ts) >= 0) { dbg3("woken up"); continue; /* don't decrement timeout! */ } if (--timeout == 0) { dbg1("%s mdev.seq='%s'", "timed out", seqbuf); break; } } sigprocmask(SIG_UNBLOCK, &set_CHLD, NULL); return seq_fd; } static void signal_mdevs(unsigned my_pid) { procps_status_t* p = NULL; while ((p = procps_scan(p, PSSCAN_ARGV0)) != NULL) { if (p->pid != my_pid && p->argv0 && strcmp(bb_basename(p->argv0), "mdev") == 0 ) { kill(p->pid, SIGCHLD); } } } static void process_action(char *temp, unsigned my_pid) { char *fw; char *seq; char *action; char *env_devname; char *env_devpath; unsigned seqnum = seqnum; /* for compiler */ int seq_fd; smalluint op; /* Hotplug: * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev * ACTION can be "add", "remove", "change" * DEVPATH is like "/block/sda" or "/class/input/mice" */ env_devname = getenv("DEVNAME"); /* can be NULL */ G.subsystem = getenv("SUBSYSTEM"); action = getenv("ACTION"); env_devpath = getenv("DEVPATH"); if (!action || !env_devpath /*|| !G.subsystem*/) bb_show_usage(); fw = getenv("FIRMWARE"); seq = getenv("SEQNUM"); op = index_in_strings(keywords, action); if (my_pid) open_mdev_log(seq, my_pid); seq_fd = -1; if (my_pid && seq) { seqnum = atoll(seq); seq_fd = wait_for_seqfile(seqnum); } dbg1("%s " "ACTION:%s SEQNUM:%s SUBSYSTEM:%s DEVNAME:%s DEVPATH:%s" "%s%s", curtime(), action, seq, G.subsystem, env_devname, env_devpath, fw ? " FW:" : "", fw ? fw : "" ); snprintf(temp, PATH_MAX, "/sys%s", env_devpath); if (op == OP_remove) { /* Ignoring "remove firmware". It was reported * to happen and to cause erroneous deletion * of device nodes. */ if (!fw) make_device(env_devname, temp, op); } else { make_device(env_devname, temp, op); if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) { if (op == OP_add && fw) load_firmware(fw, temp); } } if (seq_fd >= 0) { xwrite_str(seq_fd, utoa(seqnum + 1)); signal_mdevs(my_pid); } } static void initial_scan(char *temp) { struct stat st; xstat("/", &st); G.root_major = major(st.st_dev); G.root_minor = minor(st.st_dev); putenv((char*)"ACTION=add"); /* Create all devices from /sys/dev hierarchy */ recursive_action("/sys/dev", ACTION_RECURSE | ACTION_FOLLOWLINKS, fileAction, dirAction, temp); } #if ENABLE_FEATURE_MDEV_DAEMON /* * The kernel (as of v5.4) will pass up to 32 environment variables with a * total of 2kiB on each event. On top of that the action string and device * path are added. Using a 3kiB buffer for the event should suffice in any * case. * * As far as the socket receive buffer size is concerned 2MiB proved to be too * small (see [1]). Udevd seems to use a whooping 128MiB. The socket receive * buffer size is just a resource limit. The buffers are allocated lazily so * the memory is not wasted. * * [1] http://lists.busybox.net/pipermail/busybox/2019-December/087665.html */ # define USER_RCVBUF (3 * 1024) # define KERN_RCVBUF (128 * 1024 * 1024) # define MAX_ENV 32 static int daemon_init(char *temp) { int fd; /* Subscribe for UEVENT kernel messages */ /* Without a sufficiently big RCVBUF, a ton of simultaneous events * can trigger ENOBUFS on read, which is unrecoverable. * Reproducer: * mdev -d * find /sys -name uevent -exec sh -c 'echo add >"{}"' ';' */ fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, 1 << 0, KERN_RCVBUF); /* * Make inital scan after the uevent socket is alive and * _before_ we fork away. Already open mdev.log because we work * in daemon mode. */ initial_scan(temp); return fd; } static void daemon_loop(char *temp, int fd) { for (;;) { char netbuf[USER_RCVBUF]; char *env[MAX_ENV]; char *s, *end; ssize_t len; int idx; len = safe_read(fd, netbuf, sizeof(netbuf) - 1); if (len < 0) { if (errno == ENOBUFS) { /* * We ran out of socket receive buffer space. * Start from scratch. */ dbg1s("uevent overrun, rescanning"); close(fd); fd = daemon_init(temp); continue; } bb_simple_perror_msg_and_die("read"); } end = netbuf + len; *end = '\0'; idx = 0; s = netbuf; while (s < end && idx < MAX_ENV) { if (endofname(s)[0] == '=') { env[idx++] = s; putenv(s); } s += strlen(s) + 1; } process_action(temp, 0); while (idx) bb_unsetenv(env[--idx]); } } #endif int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int mdev_main(int argc UNUSED_PARAM, char **argv) { enum { MDEV_OPT_SCAN = 1 << 0, MDEV_OPT_SYSLOG = 1 << 1, MDEV_OPT_DAEMON = 1 << 2, MDEV_OPT_FOREGROUND = 1 << 3, }; int opt; RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE); INIT_G(); /* We can be called as hotplug helper */ /* Kernel cannot provide suitable stdio fds for us, do it ourself */ bb_sanitize_stdio(); /* Force the configuration file settings exactly */ umask(0); xchdir("/dev"); opt = getopt32(argv, "^" "sS" IF_FEATURE_MDEV_DAEMON("df") "v" "\0" "vv", &G.verbose); #if ENABLE_FEATURE_MDEV_CONF G.filename = "/etc/mdev.conf"; if (opt & (MDEV_OPT_SCAN|MDEV_OPT_DAEMON)) { /* Same as xrealloc_vector(NULL, 4, 0): */ G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec)); } #endif if (opt & MDEV_OPT_SYSLOG) { openlog(applet_name, LOG_PID, LOG_DAEMON); logmode |= LOGMODE_SYSLOG; } #if ENABLE_FEATURE_MDEV_DAEMON if (opt & MDEV_OPT_DAEMON) { /* Daemon mode listening on uevent netlink socket. Fork away * after initial scan so that caller can be sure everything * is up-to-date when mdev process returns. */ int fd = daemon_init(temp); if (!(opt & MDEV_OPT_FOREGROUND)) { /* there is no point in logging to /dev/null */ logmode &= ~LOGMODE_STDIO; bb_daemonize_or_rexec(0, argv); } daemon_loop(temp, fd); } #endif if (opt & MDEV_OPT_SCAN) { /* * Scan: mdev -s */ initial_scan(temp); } else { process_action(temp, getpid()); dbg1("%s exiting", curtime()); } if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp); return EXIT_SUCCESS; }