lvm2/libdm/libdm-common.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2012 Red Hat, Inc. All rights reserved.
 *
 * This file is part of the device-mapper userspace tools.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libdm/misc/dmlib.h"
#include "libdm-targets.h"
#include "libdm-common.h"
#include "libdm/misc/kdev_t.h"
#include "libdm/misc/dm-ioctl.h"

#include <stdarg.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <dirent.h>

#ifdef UDEV_SYNC_SUPPORT
#  include <sys/types.h>
#  include <sys/ipc.h>
#  include <sys/sem.h>
#  include <libudev.h>
#endif

#ifdef __linux__
#  include <linux/fs.h>
#endif

#ifdef HAVE_SELINUX
#  include <selinux/selinux.h>
#endif
#ifdef HAVE_SELINUX_LABEL_H
#  include <selinux/label.h>
#endif

#define DM_DEFAULT_NAME_MANGLING_MODE_ENV_VAR_NAME "DM_DEFAULT_NAME_MANGLING_MODE"

#define DEV_DIR "/dev/"

#ifdef UDEV_SYNC_SUPPORT
#ifdef _SEM_SEMUN_UNDEFINED
union semun
{
	int val;			/* value for SETVAL */
	struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */
	unsigned short int *array;	/* array for GETALL & SETALL */
	struct seminfo *__buf;		/* buffer for IPC_INFO */
};
#endif
#endif

static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR;
static char _sysfs_dir[PATH_MAX] = "/sys/";
static char _path0[PATH_MAX];           /* path buffer, safe 4kB on stack */
static const char _mountinfo[] = "/proc/self/mountinfo";

#define DM_MAX_UUID_PREFIX_LEN	15
static char _default_uuid_prefix[DM_MAX_UUID_PREFIX_LEN + 1] = "LVM-";

static int _verbose = 0;
static int _suspended_dev_counter = 0;
static dm_string_mangling_t _name_mangling_mode = DEFAULT_DM_NAME_MANGLING;

#ifdef HAVE_SELINUX_LABEL_H
static struct selabel_handle *_selabel_handle = NULL;
#endif

static int _udev_disabled = 0;

#ifdef UDEV_SYNC_SUPPORT
static int _semaphore_supported = -1;
static int _udev_running = -1;
static int _sync_with_udev = 1;
static int _udev_checking = 1;
#endif

void dm_lib_init(void)
{
	const char *env;

	if (getenv("DM_DISABLE_UDEV"))
		_udev_disabled = 1;

	_name_mangling_mode = DEFAULT_DM_NAME_MANGLING;
	if ((env = getenv(DM_DEFAULT_NAME_MANGLING_MODE_ENV_VAR_NAME))) {
		if (!strcasecmp(env, "none"))
			_name_mangling_mode = DM_STRING_MANGLING_NONE;
		else if (!strcasecmp(env, "auto"))
			_name_mangling_mode = DM_STRING_MANGLING_AUTO;
		else if (!strcasecmp(env, "hex"))
			_name_mangling_mode = DM_STRING_MANGLING_HEX;
	}
}

/*
 * Library users can provide their own logging
 * function.
 */

__attribute__((format(printf, 5, 0)))
static void _default_log_line(int level, const char *file,
			      int line, int dm_errno_or_class,
			      const char *f, va_list ap)
{
	static int _abort_on_internal_errors = -1;
	static int _debug_with_line_numbers = -1;
	FILE *out = log_stderr(level) ? stderr : stdout;

	level = log_level(level);

	if (level <= _LOG_WARN || _verbose) {
		if (level < _LOG_WARN)
			out = stderr;

		if (_debug_with_line_numbers < 0)
			/* Set when env DM_DEBUG_WITH_LINE_NUMBERS is not "0" */
			_debug_with_line_numbers =
				strcmp(getenv("DM_DEBUG_WITH_LINE_NUMBERS") ? : "0", "0");

		if (_debug_with_line_numbers)
			fprintf(out, "%s:%d     ", file, line);

		vfprintf(out, f, ap);
		fputc('\n', out);
	}

	if (_abort_on_internal_errors < 0)
		/* Set when env DM_ABORT_ON_INTERNAL_ERRORS is not "0" */
		_abort_on_internal_errors =
			strcmp(getenv("DM_ABORT_ON_INTERNAL_ERRORS") ? : "0", "0");

	if (_abort_on_internal_errors &&
	    !strncmp(f, INTERNAL_ERROR, sizeof(INTERNAL_ERROR) - 1))
		abort();
}

__attribute__((format(printf, 5, 6)))
static void _default_log_with_errno(int level,
	    const char *file, int line, int dm_errno_or_class,
	    const char *f, ...)
{
	va_list ap;

	va_start(ap, f);
	_default_log_line(level, file, line, dm_errno_or_class, f, ap);
	va_end(ap);
}

__attribute__((format(printf, 4, 5)))
static void _default_log(int level, const char *file,
			 int line, const char *f, ...)
{
	va_list ap;

	va_start(ap, f);
	_default_log_line(level, file, line, 0, f, ap);
	va_end(ap);
}

dm_log_fn dm_log = _default_log;
dm_log_with_errno_fn dm_log_with_errno = _default_log_with_errno;

/*
 * Wrapper function to reformat new messages to and
 * old style logging which had not used errno parameter
 *
 * As we cannot simply pass '...' to old function we
 * need to process arg list locally and just pass '%s' + buffer
 */
__attribute__((format(printf, 5, 6)))
static void _log_to_default_log(int level,
	    const char *file, int line, int dm_errno_or_class,
	    const char *f, ...)
{
	int n;
	va_list ap;
	char buf[2 * PATH_MAX + 256]; /* big enough for most messages */

	va_start(ap, f);
	n = vsnprintf(buf, sizeof(buf), f, ap);
	va_end(ap);

	if (n > 0) /* Could be truncated */
		dm_log(level, file, line, "%s", buf);
}

/*
 * Wrapper function take 'old' style message without errno
 * and log it via new logging function with errno arg
 *
 * This minor case may happen if new libdm is used with old
 * recompiled tool that would decided to use new logging,
 * but still would like to use old binary plugins.
 */
__attribute__((format(printf, 4, 5)))
static void _log_to_default_log_with_errno(int level,
	    const char *file, int line, const char *f, ...)
{
	int n;
	va_list ap;
	char buf[2 * PATH_MAX + 256]; /* big enough for most messages */

	va_start(ap, f);
	n = vsnprintf(buf, sizeof(buf), f, ap);
	va_end(ap);

	if (n > 0) /* Could be truncated */
		dm_log_with_errno(level, file, line, 0, "%s", buf);
}

void dm_log_init(dm_log_fn fn)
{
	if (fn)  {
		dm_log = fn;
		dm_log_with_errno = _log_to_default_log;
	} else {
		dm_log = _default_log;
		dm_log_with_errno = _default_log_with_errno;
	}
}

int dm_log_is_non_default(void)
{
	return (dm_log == _default_log && dm_log_with_errno == _default_log_with_errno) ? 0 : 1;
}

void dm_log_with_errno_init(dm_log_with_errno_fn fn)
{
	if (fn) {
		dm_log = _log_to_default_log_with_errno;
		dm_log_with_errno = fn;
	} else {
		dm_log = _default_log;
		dm_log_with_errno = _default_log_with_errno;
	}
}

void dm_log_init_verbose(int level)
{
	_verbose = level;
}

static int _build_dev_path(char *buffer, size_t len, const char *dev_name)
{
	int r;

	/* If there's a /, assume caller knows what they're doing */
	if (strchr(dev_name, '/'))
		r = dm_strncpy(buffer, dev_name, len);
	else
		r = (dm_snprintf(buffer, len, "%s/%s",
				 _dm_dir, dev_name) < 0) ? 0 : 1;
	if (!r)
		log_error("Failed to build dev path for \"%s\".", dev_name);

	return r;
}

int dm_get_library_version(char *version, size_t size)
{
	return dm_strncpy(version, DM_LIB_VERSION, size);
}

void inc_suspended(void)
{
	_suspended_dev_counter++;
	log_debug_activation("Suspended device counter increased to %d", _suspended_dev_counter);
}

void dec_suspended(void)
{
	if (!_suspended_dev_counter) {
		log_error("Attempted to decrement suspended device counter below zero.");
		return;
	}

	_suspended_dev_counter--;
	log_debug_activation("Suspended device counter reduced to %d", _suspended_dev_counter);
}

int dm_get_suspended_counter(void)
{
	return _suspended_dev_counter;
}

int dm_set_name_mangling_mode(dm_string_mangling_t name_mangling_mode)
{
	_name_mangling_mode = name_mangling_mode;

	return 1;
}

dm_string_mangling_t dm_get_name_mangling_mode(void)
{
	return _name_mangling_mode;
}

struct dm_task *dm_task_create(int type)
{
	struct dm_task *dmt = dm_zalloc(sizeof(*dmt));

	if (!dmt) {
		log_error("dm_task_create: malloc(%" PRIsize_t ") failed",
			  sizeof(*dmt));
		return NULL;
	}

	if (!dm_check_version()) {
		dm_free(dmt);
		return_NULL;
	}

	dmt->type = type;
	dmt->minor = -1;
	dmt->major = -1;
	dmt->allow_default_major_fallback = 1;
	dmt->uid = DM_DEVICE_UID;
	dmt->gid = DM_DEVICE_GID;
	dmt->mode = DM_DEVICE_MODE;
	dmt->no_open_count = 0;
	dmt->read_ahead = DM_READ_AHEAD_AUTO;
	dmt->read_ahead_flags = 0;
	dmt->event_nr = 0;
	dmt->cookie_set = 0;
	dmt->query_inactive_table = 0;
	dmt->new_uuid = 0;
	dmt->secure_data = 0;
	dmt->record_timestamp = 0;
	dmt->ima_measurement = 0;

	return dmt;
}

/*
 * Find the name associated with a given device number by scanning _dm_dir.
 */
static int _find_dm_name_of_device(dev_t st_rdev, char *buf, size_t buf_len)
{
	const char *name;
	char path[PATH_MAX];
	struct dirent *dirent;
	DIR *d;
	struct stat st;
	int r = 0;

	if (!(d = opendir(_dm_dir))) {
		log_sys_error("opendir", _dm_dir);
		return 0;
	}

	while ((dirent = readdir(d))) {
		name = dirent->d_name;

		if (!strcmp(name, ".") || !strcmp(name, ".."))
			continue;

		if (dm_snprintf(path, sizeof(path), "%s/%s", _dm_dir,
				name) == -1) {
			log_error("Couldn't create path for %s", name);
			continue;
		}

		if (stat(path, &st))
			continue;

		if (st.st_rdev == st_rdev) {
			strncpy(buf, name, buf_len);
			r = 1;
			break;
		}
	}

	if (closedir(d))
		log_sys_debug("closedir", _dm_dir);

	return r;
}

static int _is_whitelisted_char(char c)
{
	/*
	 * Actually, DM supports any character in a device name.
	 * This whitelist is just for proper integration with udev.
	 */
        if ((c >= '0' && c <= '9') ||
            (c >= 'A' && c <= 'Z') ||
            (c >= 'a' && c <= 'z') ||
            strchr("#+-.:=@_", c) != NULL)
                return 1;

        return 0;
}

int check_multiple_mangled_string_allowed(const char *str, const char *str_name,
					 dm_string_mangling_t mode)
{
	if (mode == DM_STRING_MANGLING_AUTO && strstr(str, "\\x5cx")) {
		log_error("The %s \"%s\" seems to be mangled more than once. "
			  "This is not allowed in auto mode.", str_name, str);
		return 0;
	}

	return 1;
}

/*
 * Mangle all characters in the input string which are not on a whitelist
 * with '\xNN' format where NN is the hex value of the character.
 */
int mangle_string(const char *str, const char *str_name, size_t len,
		  char *buf, size_t buf_len, dm_string_mangling_t mode)
{
	int need_mangling = -1; /* -1 don't know yet, 0 no, 1 yes */
	size_t i, j;

	if (!str || !buf)
		return -1;

	/* Is there anything to do at all? */
	if (!*str || !len)
		return 0;

	if (buf_len < DM_NAME_LEN) {
		log_error(INTERNAL_ERROR "mangle_string: supplied buffer too small");
		return -1;
	}

	if (mode == DM_STRING_MANGLING_NONE)
		mode = DM_STRING_MANGLING_AUTO;

	for (i = 0, j = 0; str[i]; i++) {
		if (mode == DM_STRING_MANGLING_AUTO) {
			/*
			 * Detect already mangled part of the string and keep it.
			 * Return error on mixture of mangled/not mangled!
			 */
			if (str[i] == '\\' && str[i+1] == 'x') {
				if ((len - i < 4) || (need_mangling == 1))
					goto bad1;
				if (buf_len - j < 4)
					goto bad2;

				memcpy(&buf[j], &str[i], 4);
				i+=3; j+=4;

				need_mangling = 0;
				continue;
			}
		}

		if (_is_whitelisted_char(str[i])) {
			/* whitelisted, keep it. */
			if (buf_len - j < 1)
				goto bad2;
			buf[j] = str[i];
			j++;
		} else {
			/*
			 * Not on a whitelist, mangle it.
			 * Return error on mixture of mangled/not mangled
			 * unless a DM_STRING_MANGLING_HEX is used!.
			 */
			if ((mode != DM_STRING_MANGLING_HEX) && (need_mangling == 0))
				goto bad1;
			if (buf_len - j < 4)
				goto bad2;

			sprintf(&buf[j], "\\x%02x", (unsigned char) str[i]);
			j+=4;

			need_mangling = 1;
		}
	}

	if (buf_len - j < 1)
		goto bad2;
	buf[j] = '\0';

	/* All chars in the string whitelisted? */
	if (need_mangling == -1)
		need_mangling = 0;

	return need_mangling;

bad1:
	log_error("The %s \"%s\" contains mixed mangled and unmangled "
		  "characters or it's already mangled improperly.", str_name, str);
	return -1;
bad2:
	log_error("Mangled form of the %s too long for \"%s\".", str_name, str);
	return -1;
}

/*
 * Try to unmangle supplied string.
 * Return value: -1 on error, 0 when no unmangling needed, 1 when unmangling applied
 */
int unmangle_string(const char *str, const char *str_name, size_t len,
		    char *buf, size_t buf_len, dm_string_mangling_t mode)
{
	int strict = mode != DM_STRING_MANGLING_NONE;
	char str_rest[DM_NAME_LEN];
	size_t i, j;
	unsigned int code;
	int r = 0;

	if (!str || !buf)
		return -1;

	/* Is there anything to do at all? */
	if (!*str || !len)
		return 0;

	if (buf_len < DM_NAME_LEN) {
		log_error(INTERNAL_ERROR "unmangle_string: supplied buffer too small");
		return -1;
	}

	for (i = 0, j = 0; str[i]; i++, j++) {
		if (strict && !(_is_whitelisted_char(str[i]) || str[i]=='\\')) {
			log_error("The %s \"%s\" should be mangled but "
				  "it contains blacklisted characters.", str_name, str);
			j=0; r=-1;
			goto out;
		}

		if (str[i] == '\\' && str[i+1] == 'x') {
			if (!sscanf(&str[i+2], "%2x%" DM_TO_STRING(DM_NAME_LEN) "s",
				    &code, str_rest)) {
				log_debug_activation("Hex encoding mismatch detected in %s \"%s\" "
						     "while trying to unmangle it.", str_name, str);
				goto out;
			}
			buf[j] = (unsigned char) code;

			/* skip the encoded part we've just decoded! */
			i+= 3;

			/* unmangling applied */
			r = 1;
		} else
			buf[j] = str[i];
	}

out:
	buf[j] = '\0';
	return r;
}

static int _dm_task_set_name(struct dm_task *dmt, const char *name,
			     dm_string_mangling_t mangling_mode)
{
	char mangled_name[DM_NAME_LEN];
	int r = 0;

	dm_free(dmt->dev_name);
	dmt->dev_name = NULL;
	dm_free(dmt->mangled_dev_name);
	dmt->mangled_dev_name = NULL;

	if (strlen(name) >= DM_NAME_LEN) {
		log_error("Name \"%s\" too long.", name);
		return 0;
	}

	if (!check_multiple_mangled_string_allowed(name, "name", mangling_mode))
		return_0;

	if (mangling_mode != DM_STRING_MANGLING_NONE &&
	    (r = mangle_string(name, "name", strlen(name), mangled_name,
			       sizeof(mangled_name), mangling_mode)) < 0) {
		log_error("Failed to mangle device name \"%s\".", name);
		return 0;
	}

	/* Store mangled_dev_name only if it differs from dev_name! */
	if (r) {
		log_debug_activation("Device name mangled [%s]: %s --> %s",
				     mangling_mode == DM_STRING_MANGLING_AUTO ? "auto" : "hex",
				     name, mangled_name);
		if (!(dmt->mangled_dev_name = dm_strdup(mangled_name))) {
			log_error("_dm_task_set_name: dm_strdup(%s) failed", mangled_name);
			return 0;
		}
	}

	if (!(dmt->dev_name = dm_strdup(name))) {
		log_error("_dm_task_set_name: strdup(%s) failed", name);
		return 0;
	}

	return 1;
}

static int _dm_task_set_name_from_path(struct dm_task *dmt, const char *path,
				       const char *name)
{
	char buf[PATH_MAX];
	struct stat st1, st2;
	const char *final_name = NULL;
	size_t len;

	if (dmt->type == DM_DEVICE_CREATE) {
		log_error("Name \"%s\" invalid. It contains \"/\".", path);
		return 0;
	}

	if (!stat(path, &st1)) {
		/*
		 * Found directly.
		 * If supplied path points to same device as last component
		 * under /dev/mapper, use that name directly.  
		 */
		if (dm_snprintf(buf, sizeof(buf), "%s/%s", _dm_dir, name) == -1) {
			log_error("Couldn't create path for %s", name);
			return 0;
		}

		if (!stat(buf, &st2) && (st1.st_rdev == st2.st_rdev))
			final_name = name;
	} else {
		/* Not found. */
		/* If there is exactly one '/' try a prefix of /dev */
		if ((len = strlen(path)) < 3 || path[0] == '/' ||
		    dm_count_chars(path, len, '/') != 1) {
			log_error("Device %s not found", path);
			return 0;
		}
		if (dm_snprintf(buf, sizeof(buf), "%s/../%s", _dm_dir, path) == -1) {
			log_error("Couldn't create /dev path for %s", path);
			return 0;
		}
		if (stat(buf, &st1)) {
			log_error("Device %s not found", path);
			return 0;
		}
		/* Found */
	}

	/*
	 * If we don't have the dm name yet, Call _find_dm_name_of_device() to
	 * scan _dm_dir for a match.
	 */
	if (!final_name) {
		if (_find_dm_name_of_device(st1.st_rdev, buf, sizeof(buf)))
			final_name = buf;
		else {
			log_error("Device %s not found", name);
			return 0;
		}
	}

	/* This is an already existing path - do not mangle! */
	return _dm_task_set_name(dmt, final_name, DM_STRING_MANGLING_NONE);
}

int dm_task_set_name(struct dm_task *dmt, const char *name)
{
	char *pos;

	/* Path supplied for existing device? */
	if ((pos = strrchr(name, '/')))
		return _dm_task_set_name_from_path(dmt, name, pos + 1);

	return _dm_task_set_name(dmt, name, dm_get_name_mangling_mode());