machine-pool.c revision 4cee5eede280b7fd48c18a1942616c4ac896a554
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2015 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/prctl.h>
#include <sys/vfs.h>
#include <sys/statvfs.h>
#include <sys/mount.h>
#include "util.h"
#include "mkdir.h"
#include "btrfs-util.h"
#include "path-util.h"
#include "machine-pool.h"
#define VAR_LIB_MACHINES_SIZE_START (1024UL*1024UL*500UL)
#define VAR_LIB_MACHINES_FREE_MIN (1024UL*1024UL*750UL)
static int check_btrfs(void) {
struct statfs sfs;
if (statfs("/var/lib/machines", &sfs) < 0) {
if (errno != ENOENT)
return -errno;
if (statfs("/var/lib", &sfs) < 0)
return -errno;
}
return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);
}
static int setup_machine_raw(uint64_t size, sd_bus_error *error) {
_cleanup_free_ char *tmp = NULL;
_cleanup_close_ int fd = -1;
struct statvfs ss;
pid_t pid = 0;
siginfo_t si;
int r;
/* We want to be able to make use of btrfs-specific file
* system features, in particular subvolumes, reflinks and
* quota. Hence, if we detect that /var/lib/machines.raw is
* not located on btrfs, let's create a loopback file, place a
* btrfs file system into it, and mount it to
* /var/lib/machines. */
fd = open("/var/lib/machines.raw", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (fd >= 0) {
r = fd;
fd = -1;
return r;
}
if (errno != ENOENT)
return sd_bus_error_set_errnof(error, errno, "Failed to open /var/lib/machines.raw: %m");
r = tempfn_xxxxxx("/var/lib/machines.raw", &tmp);
if (r < 0)
return r;
(void) mkdir_p_label("/var/lib", 0755);
fd = open(tmp, O_RDWR|O_CREAT|O_EXCL|O_NOCTTY|O_CLOEXEC, 0600);
if (fd < 0)
return sd_bus_error_set_errnof(error, errno, "Failed to create /var/lib/machines.raw: %m");
if (fstatvfs(fd, &ss) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to determine free space on /var/lib/machines.raw: %m");
goto fail;
}
if (ss.f_bsize * ss.f_bavail < VAR_LIB_MACHINES_FREE_MIN) {
r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "Not enough free disk space to set up /var/lib/machines.");
goto fail;
}
if (ftruncate(fd, size) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to enlarge /var/lib/machines.raw: %m");
goto fail;
}
pid = fork();
if (pid < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to fork mkfs.btrfs: %m");
goto fail;
}
if (pid == 0) {
/* Child */
reset_all_signal_handlers();
reset_signal_mask();
assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
fd = safe_close(fd);
execlp("mkfs.btrfs", "-Lvar-lib-machines", tmp, NULL);
if (errno == ENOENT)
return 99;
_exit(EXIT_FAILURE);
}
r = wait_for_terminate(pid, &si);
if (r < 0) {
sd_bus_error_set_errnof(error, r, "Failed to wait for mkfs.btrfs: %m");
goto fail;
}
pid = 0;
if (si.si_code != CLD_EXITED) {
r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "mkfs.btrfs died abnormally.");
goto fail;
}
if (si.si_status == 99) {
r = sd_bus_error_set_errnof(error, ENOENT, "Cannot set up /var/lib/machines, mkfs.btrfs is missing");
goto fail;
}
if (si.si_status != 0) {
r = sd_bus_error_setf(error, SD_BUS_ERROR_FAILED, "mkfs.btrfs failed with error code %i", si.si_status);
goto fail;
}
if (renameat2(AT_FDCWD, tmp, AT_FDCWD, "/var/lib/machines.raw", RENAME_NOREPLACE) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to move /var/lib/machines.raw into place: %m");
goto fail;
}
r = fd;
fd = -1;
return r;
fail:
if (tmp)
unlink_noerrno(tmp);
if (pid > 1)
kill_and_sigcont(pid, SIGKILL);
return r;
}
int setup_machine_directory(uint64_t size, sd_bus_error *error) {
_cleanup_release_lock_file_ LockFile lock_file = LOCK_FILE_INIT;
struct loop_info64 info = {
.lo_flags = LO_FLAGS_AUTOCLEAR,
};
_cleanup_close_ int fd = -1, control = -1, loop = -1;
_cleanup_free_ char* loopdev = NULL;
char tmpdir[] = "/tmp/import-mount.XXXXXX", *mntdir = NULL;
bool tmpdir_made = false, mntdir_made = false, mntdir_mounted = false;
int r, nr = -1;
/* btrfs cannot handle file systems < 16M, hence use this as minimum */
if (size == (uint64_t) -1)
size = VAR_LIB_MACHINES_SIZE_START;
else if (size < 16*1024*1024)
size = 16*1024*1024;
/* Make sure we only set the directory up once at a time */
r = make_lock_file("/run/systemd/machines.lock", LOCK_EX, &lock_file);
if (r < 0)
return r;
r = check_btrfs();
if (r < 0)
return sd_bus_error_set_errnof(error, r, "Failed to determine whether /var/lib/machines is located on btrfs: %m");
if (r > 0) {
(void) btrfs_subvol_make_label("/var/lib/machines");
r = btrfs_quota_enable("/var/lib/machines", true);
if (r < 0)
log_warning_errno(r, "Failed to enable quota, ignoring: %m");
return 0;
}
if (path_is_mount_point("/var/lib/machines", true) > 0 ||
dir_is_empty("/var/lib/machines") == 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "/var/lib/machines is not a btrfs file system. Operation is not supported on legacy file systems.");
fd = setup_machine_raw(size, error);
if (fd < 0)
return fd;
control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
if (control < 0)
return sd_bus_error_set_errnof(error, errno, "Failed to open /dev/loop-control: %m");
nr = ioctl(control, LOOP_CTL_GET_FREE);
if (nr < 0)
return sd_bus_error_set_errnof(error, errno, "Failed to allocate loop device: %m");
if (asprintf(&loopdev, "/dev/loop%i", nr) < 0) {
r = -ENOMEM;
goto fail;
}
loop = open(loopdev, O_CLOEXEC|O_RDWR|O_NOCTTY|O_NONBLOCK);
if (loop < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to open loopback device: %m");
goto fail;
}
if (ioctl(loop, LOOP_SET_FD, fd) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to bind loopback device: %m");
goto fail;
}
if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to enable auto-clear for loopback device: %m");
goto fail;
}
/* We need to make sure the new /var/lib/machines directory
* has an access mode of 0700 at the time it is first made
* available. mkfs will create it with 0755 however. Hence,
* let's mount the directory into an inaccessible directory
* below /tmp first, fix the access mode, and move it to the
* public place then. */
if (!mkdtemp(tmpdir)) {
r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount parent directory: %m");
goto fail;
}
tmpdir_made = true;
mntdir = strjoina(tmpdir, "/mnt");
if (mkdir(mntdir, 0700) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to create temporary mount directory: %m");
goto fail;
}
mntdir_made = true;
if (mount(loopdev, mntdir, "btrfs", 0, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to mount loopback device: %m");
goto fail;
}
mntdir_mounted = true;
r = btrfs_quota_enable(mntdir, true);
if (r < 0)
log_warning_errno(r, "Failed to enable quota, ignoring: %m");
if (chmod(mntdir, 0700) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to fix owner: %m");
goto fail;
}
(void) mkdir_p_label("/var/lib/machines", 0700);
if (mount(mntdir, "/var/lib/machines", NULL, MS_BIND, NULL) < 0) {
r = sd_bus_error_set_errnof(error, errno, "Failed to mount directory into right place: %m");
goto fail;
}
(void) umount2(mntdir, MNT_DETACH);
(void) rmdir(mntdir);
(void) rmdir(tmpdir);
return 0;
fail:
if (mntdir_mounted)
(void) umount2(mntdir, MNT_DETACH);
if (mntdir_made)
(void) rmdir(mntdir);
if (tmpdir_made)
(void) rmdir(tmpdir);
if (loop >= 0) {
(void) ioctl(loop, LOOP_CLR_FD);
loop = safe_close(loop);
}
if (control >= 0 && nr >= 0)
(void) ioctl(control, LOOP_CTL_REMOVE, nr);
return r;
}