lvm2/libdm/libdm-common.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2007 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 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 int _verbose = 0;
static int _suspended_dev_counter = 0;

#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

/*
 * 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;
}

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 char *_find_dm_name_of_device(dev_t st_rdev)
{
	const char *name;
	char path[PATH_MAX];
	struct dirent *dirent;
	DIR *d;
	struct stat buf;
	char *new_name = NULL;

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

	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, &buf))
			continue;

		if (buf.st_rdev == st_rdev) {
			if (!(new_name = dm_strdup(name)))
				log_error("dm_task_set_name: strdup(%s) failed",
					  name);
			break;
		}
	}

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

	return new_name;
}

int dm_task_set_name(struct dm_task *dmt, const char *name)
{
	char *pos;
	char *new_name = NULL;
	char path[PATH_MAX];
	struct stat st1, st2;

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

	/*
	 * Path supplied for existing device?
	 */
	if ((pos = strrchr(name, '/'))) {
		if (dmt->type == DM_DEVICE_CREATE) {
			log_error("Name \"%s\" invalid. It contains \"/\".", name);
			return 0;
		}

		if (stat(name, &st1)) {
			log_error("Device %s not found", name);
			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(path, sizeof(path), "%s/%s", _dm_dir,
				pos + 1) == -1) {
			log_error("Couldn't create path for %s", pos + 1);
			return 0;
		}

		if (!stat(path, &st2) && (st1.st_rdev == st2.st_rdev))
			name = pos + 1;
		else if ((new_name = _find_dm_name_of_device(st1.st_rdev)))
			name = new_name;
		else {
			log_error("Device %s not found", name);
			return 0;
		}
	}

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

	if (new_name)
		dmt->dev_name = new_name;
	else if (!(dmt->dev_name = dm_strdup(name))) {
		log_error("dm_task_set_name: strdup(%s) failed", name);
		return 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_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);
		freecon(scontext);
		return 0;
	}

	freecon(scontext);
#endif
	return 1;
}

void selinux_release(void)
{
#ifdef HAVE_SELINUX_LABEL_H
	if (_selabel_handle)
		selabel_close(_selabel_handle);
	_selabel_handle = NULL;
#endif
}

static int _warn_if_op_needed(int warn_if_udev_failed)
{
    return warn_if_udev_failed && dm_udev_get_sync_support() && dm_udev_get_checking();
}

static int _add_dev_node(const char *dev_name, uint32_t major, uint32_t minor,
			 uid_t uid, gid_t gid, mode_t mode, int warn_if_udev_failed)
{
	char path[PATH_MAX];
	struct stat info;
	dev_t dev = MKDEV(major, minor);
	mode_t old_mask;

	_build_dev_path(path, sizeof(path), dev_name);

	if (stat(path, &info) >= 0) {
		if (!S_ISBLK(info.st_mode)) {
			log_error("A non-block device file at '%s' "
				  "is already present", path);
			return 0;
		}

		/* If right inode already exists we don't touch uid etc. */
		if (info.st_rdev == dev)
			return 1;

		if (unlink(path) < 0) {
			log_error("Unable to unlink device node for '%s'",
				  dev_name);
			return 0;
		}
	} else if (_warn_if_op_needed(warn_if_udev_failed))
		log_warn("%s not set up by udev: Falling back to direct "
			 "node creation.", path);

	(void) dm_prepare_selinux_context(path, S_IFBLK);
	old_mask = umask(0);
	if (mknod(path, S_IFBLK | mode, dev) < 0) {
		log_error("%s: mknod for %s failed: %s", path, dev_name, strerror(errno));
		umask(old_mask);
		(void) dm_prepare_selinux_context(NULL, 0);
		return 0;
	}
	umask(old_mask);
	(void) dm_prepare_selinux_context(NULL, 0);

	if (chown(path, uid, gid) < 0) {
		log_sys_error("chown", path);
		return 0;
	}

	log_debug("Created %s", path);

	return 1;
}

static int _rm_dev_node(const char *dev_name, int warn_if_udev_failed)
{
	char path[PATH_MAX];
	struct stat info;

	_build_dev_path(path, sizeof(path), dev_name);

	if (stat(path, &info) < 0)
		return 1;
	else if (_warn_if_op_needed(warn_if_udev_failed))
		log_warn("Node %s was not removed by udev. "
			 "Falling back to direct node removal.", path);

	if (unlink(path) < 0) {
		log_error("Unable to unlink device node for '%s'", dev_name);
		return 0;
	}

	log_debug("Removed %s", path);

	return 1;
}

static int _rename_dev_node(const char *old_name, const char *new_name,
			    int warn_if_udev_failed)
{
	char oldpath[PATH_MAX];
	char newpath[PATH_MAX];
	struct stat info;

	_build_dev_path(oldpath, sizeof(oldpath), old_name);
	_build_dev_path(newpath, sizeof(newpath), new_name);

	if (stat(newpath, &info) == 0) {
		if (!S_ISBLK(info.st_mode)) {
			log_error("A non-block device file at '%s' "
				  "is already present", newpath);
			return 0;
		}
		else if (_warn_if_op_needed(warn_if_udev_failed)) {
			if (stat(oldpath, &info) < 0 &&
				 errno == ENOENT)
				/* assume udev already deleted this */
				return 1;
			else {
				log_warn("The node %s should have been renamed to %s "
					 "by udev but old node is still present. "
					 "Falling back to direct old node removal.",
					 oldpath, newpath);
				return _rm_dev_node(old_name, 0);
			}
		}

		if (unlink(newpath) < 0) {
			if (errno == EPERM) {
				/* devfs, entry has already been renamed */
				return 1;
			}
			log_error("Unable to unlink device node for '%s'",
				  new_name);
			return 0;
		}
	}
	else if (_warn_if_op_needed(warn_if_udev_failed))
		log_warn("The node %s should have been renamed to %s "
			 "by udev but new node is not present. "
			 "Falling back to direct node rename.",
			 oldpath, newpath);

	if (rename(oldpath, newpath) < 0) {
		log_error("Unable to rename device node from '%s' to '%s'",
			  old_name, new_name);
		return 0;
	}

	log_debug("Renamed %s to %s", oldpath, newpath);

	return 1;
}

#ifdef linux
static int _open_dev_node(const char *dev_name)
{
	int fd = -1;
	char path[PATH_MAX];

	_build_dev_path(path, sizeof(path), dev_name);

	if ((fd = open(path, O_RDONLY, 0)) < 0)
		log_sys_error("open", path);

	return fd;
}

int get_dev_node_read_ahead(const char *dev_name, uint32_t *read_ahead)
{
	int r = 1;
	int fd;
	long read_ahead_long;

	if (!*dev_name) {
		log_error("Empty device name passed to BLKRAGET");
		return 0;
	}

	if ((fd = _open_dev_node(dev_name)) < 0)
		return_0;

	if (ioctl(fd, BLKRAGET, &read_ahead_long)) {
		log_sys_error("BLKRAGET", dev_name);
		*read_ahead = 0;
		r = 0;
	}  else {
		*read_ahead = (uint32_t) read_ahead_long;
		log_debug("%s: read ahead is %" PRIu32, dev_name, *read_ahead);
	}

	if (close(fd))
		stack;

	return r;
}

static int _set_read_ahead(const char *dev_name, uint32_t read_ahead)
{
	int r = 1;
	int fd;
	long read_ahead_long = (long) read_ahead;

	if (!*dev_name) {
		log_error("Empty device name passed to BLKRAGET");
		return 0;
	}

	if ((fd = _open_dev_node(dev_name)) < 0)
		return_0;

	log_debug("%s: Setting read ahead to %" PRIu32, dev_name, read_ahead);

	if (ioctl(fd, BLKRASET, read_ahead_long)) {
		log_sys_error("BLKRASET", dev_name);
		r = 0;
	}

	if (close(fd))
		stack;

	return r;