/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2013 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 .
***/
#include
#include
#include
#include "strv.h"
#include "utf8.h"
#include "btrfs-util.h"
#include "path-util.h"
#include "copy.h"
#include "mkdir.h"
#include "machine-image.h"
static const char image_search_path[] =
"/var/lib/machines\0"
"/var/lib/container\0"
"/usr/local/lib/machines\0"
"/usr/lib/machines\0";
Image *image_unref(Image *i) {
if (!i)
return NULL;
free(i->name);
free(i->path);
free(i);
return NULL;
}
static int image_new(
ImageType t,
const char *pretty,
const char *path,
const char *filename,
bool read_only,
usec_t crtime,
usec_t mtime,
Image **ret) {
_cleanup_(image_unrefp) Image *i = NULL;
assert(t >= 0);
assert(t < _IMAGE_TYPE_MAX);
assert(pretty);
assert(filename);
assert(ret);
i = new0(Image, 1);
if (!i)
return -ENOMEM;
i->type = t;
i->read_only = read_only;
i->crtime = crtime;
i->mtime = mtime;
i->usage = i->usage_exclusive = (uint64_t) -1;
i->limit = i->limit_exclusive = (uint64_t) -1;
i->name = strdup(pretty);
if (!i->name)
return -ENOMEM;
if (path)
i->path = strjoin(path, "/", filename, NULL);
else
i->path = strdup(filename);
if (!i->path)
return -ENOMEM;
path_kill_slashes(i->path);
*ret = i;
i = NULL;
return 0;
}
static int image_make(
const char *pretty,
int dfd,
const char *path,
const char *filename,
Image **ret) {
struct stat st;
bool read_only;
int r;
assert(filename);
/* We explicitly *do* follow symlinks here, since we want to
* allow symlinking trees into /var/lib/machines/, and treat
* them normally. */
if (fstatat(dfd, filename, &st, 0) < 0)
return -errno;
read_only =
(path && path_startswith(path, "/usr")) ||
(faccessat(dfd, filename, W_OK, AT_EACCESS) < 0 && errno == EROFS);
if (S_ISDIR(st.st_mode)) {
_cleanup_close_ int fd = -1;
unsigned file_attr = 0;
if (!ret)
return 1;
if (!pretty)
pretty = filename;
fd = openat(dfd, filename, O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
if (fd < 0)
return -errno;
/* btrfs subvolumes have inode 256 */
if (st.st_ino == 256) {
struct statfs sfs;
if (fstatfs(fd, &sfs) < 0)
return -errno;
if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) {
BtrfsSubvolInfo info;
BtrfsQuotaInfo quota;
/* It's a btrfs subvolume */
r = btrfs_subvol_get_info_fd(fd, &info);
if (r < 0)
return r;
r = image_new(IMAGE_SUBVOLUME,
pretty,
path,
filename,
info.read_only || read_only,
info.otime,
0,
ret);
if (r < 0)
return r;
r = btrfs_subvol_get_quota_fd(fd, "a);
if (r >= 0) {
(*ret)->usage = quota.referred;
(*ret)->usage_exclusive = quota.exclusive;
(*ret)->limit = quota.referred_max;
(*ret)->limit_exclusive = quota.exclusive_max;
}
return 1;
}
}
/* If the IMMUTABLE bit is set, we consider the
* directory read-only. Since the ioctl is not
* supported everywhere we ignore failures. */
(void) read_attr_fd(fd, &file_attr);
/* It's just a normal directory. */
r = image_new(IMAGE_DIRECTORY,
pretty,
path,
filename,
read_only || (file_attr & FS_IMMUTABLE_FL),
0,
0,
ret);
if (r < 0)
return r;
return 1;
} else if (S_ISREG(st.st_mode) && endswith(filename, ".raw")) {
usec_t crtime = 0;
/* It's a RAW disk image */
if (!ret)
return 1;
fd_getcrtime_at(dfd, filename, &crtime, 0);
if (!pretty)
pretty = strndupa(filename, strlen(filename) - 4);
r = image_new(IMAGE_RAW,
pretty,
path,
filename,
!(st.st_mode & 0222) || read_only,
crtime,
timespec_load(&st.st_mtim),
ret);
if (r < 0)
return r;
(*ret)->usage = (*ret)->usage_exclusive = st.st_blocks * 512;
(*ret)->limit = (*ret)->limit_exclusive = st.st_size;
return 1;
}
return 0;
}
int image_find(const char *name, Image **ret) {
const char *path;
int r;
assert(name);
/* There are no images with invalid names */
if (!image_name_is_valid(name))
return 0;
NULSTR_FOREACH(path, image_search_path) {
_cleanup_closedir_ DIR *d = NULL;
d = opendir(path);
if (!d) {
if (errno == ENOENT)
continue;
return -errno;
}
r = image_make(NULL, dirfd(d), path, name, ret);
if (r == 0 || r == -ENOENT) {
_cleanup_free_ char *raw = NULL;
raw = strappend(name, ".raw");
if (!raw)
return -ENOMEM;
r = image_make(NULL, dirfd(d), path, raw, ret);
if (r == 0 || r == -ENOENT)
continue;
}
if (r < 0)
return r;
return 1;
}
if (streq(name, ".host"))
return image_make(".host", AT_FDCWD, NULL, "/", ret);
return 0;
};
int image_discover(Hashmap *h) {
const char *path;
int r;
assert(h);
NULSTR_FOREACH(path, image_search_path) {
_cleanup_closedir_ DIR *d = NULL;
struct dirent *de;
d = opendir(path);
if (!d) {
if (errno == ENOENT)
continue;
return -errno;
}
FOREACH_DIRENT_ALL(de, d, return -errno) {
_cleanup_(image_unrefp) Image *image = NULL;
if (!image_name_is_valid(de->d_name))
continue;
if (hashmap_contains(h, de->d_name))
continue;
r = image_make(NULL, dirfd(d), path, de->d_name, &image);
if (r == 0 || r == -ENOENT)
continue;
if (r < 0)
return r;
r = hashmap_put(h, image->name, image);
if (r < 0)
return r;
image = NULL;
}
}
if (!hashmap_contains(h, ".host")) {
_cleanup_(image_unrefp) Image *image = NULL;
r = image_make(".host", AT_FDCWD, NULL, "/", &image);
if (r < 0)
return r;
r = hashmap_put(h, image->name, image);
if (r < 0)
return r;
image = NULL;
}
return 0;
}
void image_hashmap_free(Hashmap *map) {
Image *i;
while ((i = hashmap_steal_first(map)))
image_unref(i);
hashmap_free(map);
}
int image_remove(Image *i) {
_cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT;
int r;
assert(i);
if (path_equal(i->path, "/") ||
path_startswith(i->path, "/usr"))
return -EROFS;
/* Make sure we don't interfere with a running nspawn */
r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock);
if (r < 0)
return r;
switch (i->type) {
case IMAGE_SUBVOLUME:
return btrfs_subvol_remove(i->path);
case IMAGE_DIRECTORY:
/* Allow deletion of read-only directories */
(void) chattr_path(i->path, false, FS_IMMUTABLE_FL);
/* fall through */
case IMAGE_RAW:
return rm_rf_dangerous(i->path, false, true, false);
default:
return -ENOTSUP;
}
}
int image_rename(Image *i, const char *new_name) {
_cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT, name_lock = LOCK_FILE_INIT;
_cleanup_free_ char *new_path = NULL, *nn = NULL;
unsigned file_attr = 0;
int r;
assert(i);
if (!image_name_is_valid(new_name))
return -EINVAL;
if (path_equal(i->path, "/") ||
path_startswith(i->path, "/usr"))
return -EROFS;
/* Make sure we don't interfere with a running nspawn */
r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock);
if (r < 0)
return r;
/* Make sure nobody takes the new name, between the time we
* checked it is currently unused in all search paths, and the
* time we take possesion of it */
r = image_name_lock(new_name, LOCK_EX|LOCK_NB, &name_lock);
if (r < 0)
return r;
r = image_find(new_name, NULL);
if (r < 0)
return r;
if (r > 0)
return -EEXIST;
switch (i->type) {
case IMAGE_DIRECTORY:
/* Turn of the immutable bit while we rename the image, so that we can rename it */
(void) read_attr_path(i->path, &file_attr);
if (file_attr & FS_IMMUTABLE_FL)
(void) chattr_path(i->path, false, FS_IMMUTABLE_FL);
/* fall through */
case IMAGE_SUBVOLUME:
new_path = file_in_same_dir(i->path, new_name);
break;
case IMAGE_RAW: {
const char *fn;
fn = strappenda(new_name, ".raw");
new_path = file_in_same_dir(i->path, fn);
break;
}
default:
return -ENOTSUP;
}
if (!new_path)
return -ENOMEM;
nn = strdup(new_name);
if (!nn)
return -ENOMEM;
if (renameat2(AT_FDCWD, i->path, AT_FDCWD, new_path, RENAME_NOREPLACE) < 0)
return -errno;
/* Restore the immutable bit, if it was set before */
if (file_attr & FS_IMMUTABLE_FL)
(void) chattr_path(new_path, true, FS_IMMUTABLE_FL);
free(i->path);
i->path = new_path;
new_path = NULL;
free(i->name);
i->name = nn;
nn = NULL;
return 0;
}
int image_clone(Image *i, const char *new_name, bool read_only) {
_cleanup_release_lock_file_ LockFile name_lock = LOCK_FILE_INIT;
const char *new_path;
int r;
assert(i);
if (!image_name_is_valid(new_name))
return -EINVAL;
/* Make sure nobody takes the new name, between the time we
* checked it is currently unused in all search paths, and the
* time we take possesion of it */
r = image_name_lock(new_name, LOCK_EX|LOCK_NB, &name_lock);
if (r < 0)
return r;
r = image_find(new_name, NULL);
if (r < 0)
return r;
if (r > 0)
return -EEXIST;
switch (i->type) {
case IMAGE_SUBVOLUME:
case IMAGE_DIRECTORY:
new_path = strappenda("/var/lib/machines/", new_name);
r = btrfs_subvol_snapshot(i->path, new_path, read_only, true);
break;
case IMAGE_RAW:
new_path = strappenda("/var/lib/machines/", new_name, ".raw");
r = copy_file_atomic(i->path, new_path, read_only ? 0444 : 0644, false, FS_NOCOW_FL);
break;
default:
return -ENOTSUP;
}
if (r < 0)
return r;
return 0;
}
int image_read_only(Image *i, bool b) {
_cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT;
int r;
assert(i);
if (path_equal(i->path, "/") ||
path_startswith(i->path, "/usr"))
return -EROFS;
/* Make sure we don't interfere with a running nspawn */
r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock);
if (r < 0)
return r;
switch (i->type) {
case IMAGE_SUBVOLUME:
r = btrfs_subvol_set_read_only(i->path, b);
if (r < 0)
return r;
break;
case IMAGE_DIRECTORY:
/* For simple directory trees we cannot use the access
mode of the top-level directory, since it has an
effect on the container itself. However, we can
use the "immutable" flag, to at least make the
top-level directory read-only. It's not as good as
a read-only subvolume, but at least something, and
we can read the value back.*/
r = chattr_path(i->path, b, FS_IMMUTABLE_FL);
if (r < 0)
return r;
break;
case IMAGE_RAW: {
struct stat st;
if (stat(i->path, &st) < 0)
return -errno;
if (chmod(i->path, (st.st_mode & 0444) | (b ? 0000 : 0200)) < 0)
return -errno;
/* If the images is now read-only, it's a good time to
* defrag it, given that no write patterns will
* fragment it again. */
if (b)
(void) btrfs_defrag(i->path);
break;
}
default:
return -ENOTSUP;
}
return 0;
}
int image_path_lock(const char *path, int operation, LockFile *global, LockFile *local) {
_cleanup_free_ char *p = NULL;
LockFile t = LOCK_FILE_INIT;
struct stat st;
int r;
assert(path);
assert(global);
assert(local);
/* Locks an image path. This actually creates two locks: one
* "local" one, next to the image path itself, which might be
* shared via NFS. And another "global" one, in /run, that
* uses the device/inode number. This has the benefit that we
* can even lock a tree that is a mount point, correctly. */
if (path_equal(path, "/"))
return -EBUSY;
if (!path_is_absolute(path))
return -EINVAL;
if (stat(path, &st) >= 0) {
if (asprintf(&p, "/run/systemd/nspawn/locks/inode-%lu:%lu", (unsigned long) st.st_dev, (unsigned long) st.st_ino) < 0)
return -ENOMEM;
}
r = make_lock_file_for(path, operation, &t);
if (r < 0)
return r;
if (p) {
mkdir_p("/run/systemd/nspawn/locks", 0600);
r = make_lock_file(p, operation, global);
if (r < 0) {
release_lock_file(&t);
return r;
}
}
*local = t;
return 0;
}
int image_name_lock(const char *name, int operation, LockFile *ret) {
const char *p;
assert(name);
assert(ret);
/* Locks an image name, regardless of the precise path used. */
if (!image_name_is_valid(name))
return -EINVAL;
if (streq(name, ".host"))
return -EBUSY;
mkdir_p("/run/systemd/nspawn/locks", 0600);
p = strappenda("/run/systemd/nspawn/locks/name-", name);
return make_lock_file(p, operation, ret);
}
bool image_name_is_valid(const char *s) {
if (!filename_is_valid(s))
return false;
if (string_has_cc(s, NULL))
return false;
if (!utf8_is_valid(s))
return false;
/* Temporary files for atomically creating new files */
if (startswith(s, ".#"))
return false;
return true;
}
static const char* const image_type_table[_IMAGE_TYPE_MAX] = {
[IMAGE_DIRECTORY] = "directory",
[IMAGE_SUBVOLUME] = "subvolume",
[IMAGE_RAW] = "raw",
};
DEFINE_STRING_TABLE_LOOKUP(image_type, ImageType);