/* 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 GPL version 2, see file LICENSE in this tarball for details. */ #include "libbb.h" #include "xregex.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 $FIRMWARE) * * If /etc/mdev.conf exists, it may modify /dev/device_name's properties. * /etc/mdev.conf file format: * * [-][subsystem/]device user:grp mode [>|=path] [@|$|*command args...] * [-]@maj,min[-min2] user:grp mode [>|=path] [@|$|*command args...] * [-]$envvar=val user:grp mode [>|=path] [@|$|*command args...] * * Leading minus in 1st field means "don't stop on this line", otherwise * search is stopped after the matching line is encountered. * * The device name or "subsystem/device" combo is matched against 1st field * (which is a regex), or maj,min is matched against 1st field, * or specified environment variable (as regex) is matched against 1st field. * * $envvar=val 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. */ struct globals { int root_major, root_minor; char *subsystem; } FIX_ALIASING; #define G (*(struct globals*)&bb_common_bufsiz1) #define root_major (G.root_major) #define root_minor (G.root_minor) #define subsystem (G.subsystem ) /* Prevent infinite loops in /sys symlinks */ #define MAX_SYSFS_DEPTH 3 /* We use additional 64+ bytes in make_device() */ #define SCRATCH_SIZE 80 /* 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 */ bb_make_directory(alias, 0755, FILEUTILS_RECUR); *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 (IOW: to restore if needed) * path string. * NB2: "mdev -s" may call us many times, do not leak memory/fds! */ static void make_device(char *path, int delete) { char *device_name; int major, minor, type, len; mode_t mode; parser_t *parser; /* 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 (!delete) { char *dev_maj_min = path + strlen(path); strcpy(dev_maj_min, "/dev"); len = open_read_close(path, dev_maj_min + 1, 64); *dev_maj_min = '\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(++dev_maj_min, "%u:%u", &major, &minor) != 2) { major = -1; } } /* Determine device name, type, major and minor */ device_name = (char*) bb_basename(path); /* 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/")) type = S_IFBLK; /* Make path point to "subsystem/device_name" */ if (path[5] == 'b') /* legacy /sys/block? */ path += sizeof("/sys/") - 1; else path += sizeof("/sys/class/") - 1; /* If we have config file, look up user settings */ if (ENABLE_FEATURE_MDEV_CONF) parser = config_open2("/etc/mdev.conf", fopen_for_read); do { int keep_matching; struct bb_uidgid_t ugid; char *tokens[4]; char *command = NULL; char *alias = NULL; char aliaslink = aliaslink; /* for compiler */ /* Defaults in case we won't match any line */ ugid.uid = ugid.gid = 0; keep_matching = 0; mode = 0660; if (ENABLE_FEATURE_MDEV_CONF && config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL) ) { char *val; char *str_to_match; regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP]; val = tokens[0]; keep_matching = ('-' == val[0]); val += keep_matching; /* swallow leading dash */ /* Match against either "subsystem/device_name" * or "device_name" alone */ str_to_match = strchr(val, '/') ? path : device_name; /* Fields: regex uid:gid mode [alias] [cmd] */ if (val[0] == '@') { /* @major,minor[-minor2] */ /* (useful when name is ambiguous: * "/sys/class/usb/lp0" and * "/sys/class/printer/lp0") */ int cmaj, cmin0, cmin1, sc; if (major < 0) continue; /* no dev, no match */ sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1); if (sc < 1 || major != cmaj || (sc == 2 && minor != cmin0) || (sc == 3 && (minor < cmin0 || minor > cmin1)) ) { continue; /* this line doesn't match */ } goto line_matches; } if (val[0] == '$') { /* regex to match an environment variable */ char *eq = strchr(++val, '='); if (!eq) continue; *eq = '\0'; str_to_match = getenv(val); if (!str_to_match) continue; str_to_match -= strlen(val) + 1; *eq = '='; } /* else: regex to match [subsystem/]device_name */ { regex_t match; int result; xregcomp(&match, val, REG_EXTENDED); result = regexec(&match, str_to_match, ARRAY_SIZE(off), off, 0); regfree(&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 no match, skip rest of line */ /* (regexec returns whole pattern as "range" 0) */ if (result || off[0].rm_so || ((int)off[0].rm_eo != (int)strlen(str_to_match)) ) { continue; /* this line doesn't match */ } } line_matches: /* This line matches. Stop parsing after parsing * the rest the line unless keep_matching == 1 */ /* 2nd field: uid:gid - device ownership */ if (get_uidgid(&ugid, tokens[1], 1) == 0) bb_error_msg("unknown user/group %s on line %d", tokens[1], parser->lineno); /* 3rd field: mode - device permissions */ /* mode = strtoul(tokens[2], NULL, 8); */ bb_parse_mode(tokens[2], &mode); val = tokens[3]; /* 4th field (opt): >|=alias */ if (ENABLE_FEATURE_MDEV_RENAME && val) { aliaslink = val[0]; if (aliaslink == '>' || aliaslink == '=') { char *a, *s, *st; char *p; unsigned i, n; a = val; s = strchrnul(val, ' '); st = strchrnul(val, '\t'); if (st < s) s = st; val = (s[0] && s[1]) ? s+1 : NULL; s[0] = '\0'; if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) { /* substitute %1..9 with off[1..9], if any */ n = 0; s = a; while (*s) if (*s++ == '%') n++; p = alias = xzalloc(strlen(a) + n * strlen(str_to_match)); s = a + 1; while (*s) { *p = *s; if ('%' == *s) { 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(a + 1); } } } if (ENABLE_FEATURE_MDEV_EXEC && val) { const char *s = "$@*"; const char *s2 = strchr(s, val[0]); if (!s2) { bb_error_msg("bad line %u", parser->lineno); if (ENABLE_FEATURE_MDEV_RENAME) free(alias); continue; } /* Are we running this command now? * Run $cmd on delete, @cmd on create, *cmd on both */ if (s2-s != delete) command = xstrdup(val + 1); } } /* End of field parsing */ /* "Execute" the line we found */ { const char *node_name; node_name = device_name; if (ENABLE_FEATURE_MDEV_RENAME && alias) node_name = alias = build_alias(alias, device_name); if (!delete && major >= 0) { if (mknod(node_name, mode | type, makedev(major, minor)) && errno != EEXIST) bb_perror_msg("can't create %s", node_name); if (major == root_major && minor == root_minor) symlink(node_name, "root"); if (ENABLE_FEATURE_MDEV_CONF) { chmod(node_name, mode); chown(node_name, ugid.uid, ugid.gid); } if (ENABLE_FEATURE_MDEV_RENAME && alias) { if (aliaslink == '>') 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); char *s1 = xasprintf("%s=%s", "SUBSYSTEM", subsystem); putenv(s); putenv(s1); if (system(command) == -1) bb_perror_msg("can't run '%s'", command); unsetenv("SUBSYSTEM"); free(s1); unsetenv("MDEV"); free(s); free(command); } if (delete) { if (ENABLE_FEATURE_MDEV_RENAME && alias) { if (aliaslink == '>') unlink(device_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 && !keep_matching) break; /* end of "while line is read from /etc/mdev.conf" */ } while (ENABLE_FEATURE_MDEV_CONF); if (ENABLE_FEATURE_MDEV_CONF) config_close(parser); } /* File callback for /sys/ traversal */ static int FAST_FUNC fileAction(const char *fileName, struct stat *statbuf UNUSED_PARAM, void *userData, int depth UNUSED_PARAM) { size_t len = strlen(fileName) - 4; /* can't underflow */ char *scratch = userData; /* len check is for paranoid reasons */ if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX) return FALSE; strcpy(scratch, fileName); scratch[len] = '\0'; make_device(scratch, 0); return TRUE; } /* Directory callback for /sys/ traversal */ static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM, struct stat *statbuf UNUSED_PARAM, void *userData UNUSED_PARAM, int depth) { /* Extract device subsystem -- the name of the directory * under /sys/class/ */ if (1 == depth) { free(subsystem); subsystem = strrchr(fileName, '/'); if (subsystem) subsystem = xstrdup(subsystem + 1); } return (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/$DEVPATH/loading * - kernel loads firmware into device */ static void load_firmware(const char *firmware, const char *sysfs_path) { int cnt; int firmware_fd, loading_fd, data_fd; /* check for /lib/firmware/$FIRMWARE */ xchdir("/lib/firmware"); firmware_fd = xopen(firmware, O_RDONLY); /* in case we goto out ... */ data_fd = -1; /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */ xchdir(sysfs_path); for (cnt = 0; cnt < 30; ++cnt) { loading_fd = open("loading", O_WRONLY); if (loading_fd != -1) goto loading; sleep(1); } goto out; loading: /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */ if (full_write(loading_fd, "1", 1) != 1) goto out; /* load firmware into /sys/$DEVPATH/data */ data_fd = open("data", O_WRONLY); if (data_fd == -1) goto out; cnt = bb_copyfd_eof(firmware_fd, data_fd); /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */ if (cnt > 0) full_write(loading_fd, "0", 1); else full_write(loading_fd, "-1", 2); out: if (ENABLE_FEATURE_CLEAN_UP) { close(firmware_fd); close(loading_fd); close(data_fd); } } int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int mdev_main(int argc UNUSED_PARAM, char **argv) { RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE); /* 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"); if (argv[1] && strcmp(argv[1], "-s") == 0) { /* Scan: * mdev -s */ struct stat st; xstat("/", &st); root_major = major(st.st_dev); root_minor = minor(st.st_dev); /* ACTION_FOLLOWLINKS is needed since in newer kernels * /sys/block/loop* (for example) are symlinks to dirs, * not real directories. * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs, * but we can't enforce that on users) */ if (access("/sys/class/block", F_OK) != 0) { /* Scan obsolete /sys/block only if /sys/class/block * doesn't exist. Otherwise we'll have dupes. * Also, do not complain if it doesn't exist. * Some people configure kernel to have no blockdevs. */ recursive_action("/sys/block", ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET, fileAction, dirAction, temp, 0); } recursive_action("/sys/class", ACTION_RECURSE | ACTION_FOLLOWLINKS, fileAction, dirAction, temp, 0); } else { char *fw; char *seq; char *action; char *env_path; static const char keywords[] ALIGN1 = "remove\0add\0"; enum { OP_remove = 0, OP_add }; smalluint op; /* Hotplug: * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev * ACTION can be "add" or "remove" * DEVPATH is like "/block/sda" or "/class/input/mice" */ action = getenv("ACTION"); env_path = getenv("DEVPATH"); subsystem = getenv("SUBSYSTEM"); if (!action || !env_path /*|| !subsystem*/) bb_show_usage(); fw = getenv("FIRMWARE"); op = index_in_strings(keywords, action); /* 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 */ seq = getenv("SEQNUM"); if (seq) { int timeout = 2000 / 32; /* 2000 msec */ do { int seqlen; char seqbuf[sizeof(int)*3 + 2]; seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1)); if (seqlen < 0) { seq = NULL; break; } seqbuf[seqlen] = '\0'; if (seqbuf[0] == '\n' /* seed file? */ || strcmp(seq, seqbuf) == 0 /* correct idx? */ ) { break; } usleep(32*1000); } while (--timeout); } snprintf(temp, PATH_MAX, "/sys%s", env_path); if (op == OP_remove) { /* Ignoring "remove firmware". It was reported * to happen and to cause erroneous deletion * of device nodes. */ if (!fw) make_device(temp, 1); } else if (op == OP_add) { make_device(temp, 0); if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) { if (fw) load_firmware(fw, temp); } } if (seq) { xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1)); } } if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp); return EXIT_SUCCESS; }