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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "dmlib.h"
#include "libdm-targets.h"
#include "libdm-common.h"
#include "kdev_t.h"
#include "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 */

#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 int _name_mangling_mode = -1;

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

#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;

	env = getenv(DM_DEFAULT_NAME_MANGLING_MODE_ENV_VAR_NAME);
	if (env && *env) {
		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;
	} else
		_name_mangling_mode = DEFAULT_DM_NAME_MANGLING;
}

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

__attribute__((format(printf, 5, 0)))
static void _default_log_line(int level,
	    const char *file __attribute__((unused)),
	    int line __attribute__((unused)), int dm_errno, 
	    const char *f, va_list ap)
{
	int use_stderr = level & _LOG_STDERR;

	level &= ~_LOG_STDERR;

	if (level > _LOG_WARN && !_verbose)
		return;

	if (level < _LOG_WARN)
		vfprintf(stderr, f, ap);
	else
		vfprintf(use_stderr ? stderr : stdout, f, ap);

	if (level < _LOG_WARN)
		fprintf(stderr, "\n");
	else
		fprintf(use_stderr ? stderr : stdout, "\n");
}

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

	va_start(ap, f);
	_default_log_line(level, file, line, dm_errno, 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;

void dm_log_init(dm_log_fn fn)
{
	if (fn)
		dm_log = fn;
	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) ? 0 : 1;
}

void dm_log_with_errno_init(dm_log_with_errno_fn fn)
{
	if (fn)
		dm_log_with_errno = fn;
	else
		dm_log_with_errno = _default_log_with_errno;

	dm_log = _default_log;
}

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

static void _build_dev_path(char *buffer, size_t len, const char *dev_name)
{
	/* If there's a /, assume caller knows what they're doing */
	if (strchr(dev_name, '/'))
		snprintf(buffer, len, "%s", dev_name);
	else
		snprintf(buffer, len, "%s/%s", _dm_dir, dev_name);
}

int dm_get_library_version(char *version, size_t size)
{
	strncpy(version, DM_LIB_VERSION, size);
	return 1;
}

void inc_suspended(void)
{
	_suspended_dev_counter++;
	log_debug("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("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;

	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_error("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;
}

/*
 * 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_name(const char *str, 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 || mode == DM_STRING_MANGLING_NONE)
		return 0;

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

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

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

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

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

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

	for (i = 0, j = 0; str[i]; i++, j++) {
		if (str[i] == '\\' && str[i+1] == 'x') {
			if (!sscanf(&str[i+2], "%2x%s", &code, str_rest)) {
				log_debug("Hex encoding mismatch detected in \"%s\" "
					  "while trying to unmangle it.", 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;

	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 ((r = mangle_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("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;

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

	if (stat(path, &st1)) {
		log_error("Device %s not found", path);
		return 0;
	}

	/*
	 * If supplied path points to same device as last component
	 * under /dev/mapper, use that name directly.  Otherwise call
	 * _find_dm_name_of_device() to scan _dm_dir for a match.
	 */
	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(path, &st2) && (st1.st_rdev == st2.st_rdev))
		final_name = name;
	else 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());
}

const char *dm_task_get_name(const struct dm_task *dmt)
{
	return (dmt->dmi.v4->name);
}

char *dm_task_get_name_mangled(const struct dm_task *dmt)
{
	const char *s = dm_task_get_name(dmt);
	char buf[DM_NAME_LEN];
	char *rs = NULL;
	int r;

	/*
	 * We're using 'auto mangling' here. If the name is already mangled,
	 * this is detected and we keep it as it is. If the name is not mangled,
	 * we do mangle it. This way we always get a mangled form of the name.
	 */
	if ((r = mangle_name(s, strlen(s), buf, sizeof(buf),
			     DM_STRING_MANGLING_AUTO)) < 0)
		log_error("Failed to mangle device name \"%s\".", s);
	else if (!(rs = r ? dm_strdup(buf) : dm_strdup(s)))
		log_error("dm_task_get_name_mangled: dm_strdup failed");

	return rs;
}

char *dm_task_get_name_unmangled(const struct dm_task *dmt)
{
	const char *s = dm_task_get_name(dmt);
	char buf[DM_NAME_LEN];
	char *rs = NULL;
	int r;

	/*
	 * We just want to unmangle the string.
	 * Both auto and hex mode will do it.
	 */
	if ((r = unmangle_name(s, strlen(s), buf, sizeof(buf),
			       DM_STRING_MANGLING_AUTO)) < 0)
		log_error("Failed to unmangle device name \"%s\".", s);
	else if (!(rs = r ? dm_strdup(buf) : dm_strdup(s)))
		log_error("dm_task_get_name_unmangled: dm_strdup failed");

	return rs;
}

int dm_task_set_newname(struct dm_task *dmt, const char *newname)
{
	dm_string_mangling_t mangling_mode = dm_get_name_mangling_mode();
	char mangled_name[DM_NAME_LEN];
	int r;

	if (strchr(newname, '/')) {
		log_error("Name \"%s\" invalid. It contains \"/\".", newname);
		return 0;
	}

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

	if ((r = mangle_name(newname, strlen(newname), mangled_name,
			     sizeof(mangled_name), mangling_mode)) < 0) {
		log_error("Failed to mangle new device name \"%s\"", newname);
		return 0;
	}

	if (r) {
		log_debug("New device name mangled [%s]: %s --> %s",
			  mangling_mode == DM_STRING_MANGLING_AUTO ? "auto" : "hex",
			  newname, mangled_name);
		newname = mangled_name;
	}

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

	dmt->new_uuid = 0;

	return 1;
}

int dm_task_set_uuid(struct dm_task *dmt, const char *uuid)
{
	dm_free(dmt->uuid);

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

	return 1;
}

int dm_task_set_major(struct dm_task *dmt, int major)
{
	dmt->major = major;
	dmt->allow_default_major_fallback = 0;

	return 1;
}

int dm_task_set_minor(struct dm_task *dmt, int minor)
{
	dmt->minor = minor;

	return 1;
}

int dm_task_set_major_minor(struct dm_task *dmt, int major, int minor,
			    int allow_default_major_fallback)
{
	dmt->major = major;
	dmt->minor = minor;
	dmt->allow_default_major_fallback = allow_default_major_fallback;

	return 1;
}

int dm_task_set_uid(struct dm_task *dmt, uid_t uid)
{
	dmt->uid = uid;

	return 1;
}

int dm_task_set_gid(struct dm_task *dmt, gid_t gid)
{
	dmt->gid = gid;

	return 1;
}

int dm_task_set_mode(struct dm_task *dmt, mode_t mode)
{
	dmt->mode = mode;

	return 1;
}

int dm_task_enable_checks(struct dm_task *dmt)
{
	dmt->enable_checks = 1;

	return 1;
}

int dm_task_add_target(struct dm_task *dmt, uint64_t start, uint64_t size,
		       const char *ttype, const char *params)
{
	struct target *t = create_target(start, size, ttype, params);
	if (!t)
		return_0;

	if (!dmt->head)
		dmt->head = dmt->tail = t;
	else {
		dmt->tail->next = t;
		dmt->tail = t;
	}

	return 1;
}

#ifdef HAVE_SELINUX
static int _selabel_lookup(const char *path, mode_t mode,
			   security_context_t *scontext)
{
#ifdef HAVE_SELINUX_LABEL_H
	if (!_selabel_handle &&
	    !(_selabel_handle = selabel_open(SELABEL_CTX_FILE, NULL, 0))) {
		log_error("selabel_open failed: %s", strerror(errno));
		return 0;
	}

	if (selabel_lookup(_selabel_handle, scontext, path, mode)) {
		log_debug("selabel_lookup failed for %s: %s",
			  path, strerror(errno));
		return 0;
	}
#else
	if (matchpathcon(path, mode, scontext)) {
		log_debug("matchpathcon failed for %s: %s",
			  path, strerror(errno));
		return 0;
	}
#endif
	return 1;
}
#endif

int dm_prepare_selinux_context(const char *path, mode_t mode)
{
#ifdef HAVE_SELINUX
	security_context_t scontext = NULL;

	if (is_selinux_enabled() <= 0)
		return 1;

	if (path) {
		if (!_selabel_lookup(path, mode, &scontext))
			return_0;

		log_debug("Preparing SELinux context for %s to %s.", path, scontext);
	}
	else
		log_debug("Resetting SELinux context to default value.");

	if (setfscreatecon(scontext) < 0) {
		log_sys_error("setfscreatecon", path);
		freecon(scontext);
		return 0;
	}

	freecon(scontext);
#endif
	return 1;
}

int dm_set_selinux_context(const char *path, mode_t mode)
{
#ifdef HAVE_SELINUX
	security_context_t scontext;

	if (is_selinux_enabled() <= 0)
		return 1;

	if (!_selabel_lookup(path, mode, &scontext))
		return_0;

	log_debug("Setting SELinux context for %s to %s.", path, scontext);

	if ((lsetfilecon(path, scontext) < 0) && (errno != ENOTSUP)) {
		log_sys_error("lsetfilecon", path);