diff options
Diffstat (limited to 'src/systemd-nspawn/nspawn-mount.c')
| -rw-r--r-- | src/systemd-nspawn/nspawn-mount.c | 1164 |
1 files changed, 1164 insertions, 0 deletions
diff --git a/src/systemd-nspawn/nspawn-mount.c b/src/systemd-nspawn/nspawn-mount.c new file mode 100644 index 0000000000..aac04efd4b --- /dev/null +++ b/src/systemd-nspawn/nspawn-mount.c @@ -0,0 +1,1164 @@ +/*** + 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/mount.h> + +#include <linux/magic.h> + +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/escape.h" +#include "systemd-basic/fd-util.h" +#include "systemd-basic/fileio.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/label.h" +#include "systemd-basic/mkdir.h" +#include "systemd-basic/mount-util.h" +#include "systemd-basic/parse-util.h" +#include "systemd-basic/path-util.h" +#include "systemd-basic/rm-rf.h" +#include "systemd-basic/set.h" +#include "systemd-basic/stat-util.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/strv.h" +#include "systemd-basic/user-util.h" +#include "systemd-basic/util.h" + +#include "nspawn-mount.h" + +CustomMount* custom_mount_add(CustomMount **l, unsigned *n, CustomMountType t) { + CustomMount *c, *ret; + + assert(l); + assert(n); + assert(t >= 0); + assert(t < _CUSTOM_MOUNT_TYPE_MAX); + + c = realloc(*l, (*n + 1) * sizeof(CustomMount)); + if (!c) + return NULL; + + *l = c; + ret = *l + *n; + (*n)++; + + *ret = (CustomMount) { .type = t }; + + return ret; +} + +void custom_mount_free_all(CustomMount *l, unsigned n) { + unsigned i; + + for (i = 0; i < n; i++) { + CustomMount *m = l + i; + + free(m->source); + free(m->destination); + free(m->options); + + if (m->work_dir) { + (void) rm_rf(m->work_dir, REMOVE_ROOT|REMOVE_PHYSICAL); + free(m->work_dir); + } + + strv_free(m->lower); + } + + free(l); +} + +int custom_mount_compare(const void *a, const void *b) { + const CustomMount *x = a, *y = b; + int r; + + r = path_compare(x->destination, y->destination); + if (r != 0) + return r; + + if (x->type < y->type) + return -1; + if (x->type > y->type) + return 1; + + return 0; +} + +int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only) { + _cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL; + const char *p = s; + CustomMount *m; + int r; + + assert(l); + assert(n); + + r = extract_many_words(&p, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &source, &destination, NULL); + if (r < 0) + return r; + if (r == 0) + return -EINVAL; + + if (r == 1) { + destination = strdup(source); + if (!destination) + return -ENOMEM; + } + + if (r == 2 && !isempty(p)) { + opts = strdup(p); + if (!opts) + return -ENOMEM; + } + + if (!path_is_absolute(source)) + return -EINVAL; + + if (!path_is_absolute(destination)) + return -EINVAL; + + m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND); + if (!m) + return log_oom(); + + m->source = source; + m->destination = destination; + m->read_only = read_only; + m->options = opts; + + source = destination = opts = NULL; + return 0; +} + +int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s) { + _cleanup_free_ char *path = NULL, *opts = NULL; + const char *p = s; + CustomMount *m; + int r; + + assert(l); + assert(n); + assert(s); + + r = extract_first_word(&p, &path, ":", EXTRACT_DONT_COALESCE_SEPARATORS); + if (r < 0) + return r; + if (r == 0) + return -EINVAL; + + if (isempty(p)) + opts = strdup("mode=0755"); + else + opts = strdup(p); + if (!opts) + return -ENOMEM; + + if (!path_is_absolute(path)) + return -EINVAL; + + m = custom_mount_add(l, n, CUSTOM_MOUNT_TMPFS); + if (!m) + return -ENOMEM; + + m->destination = path; + m->options = opts; + + path = opts = NULL; + return 0; +} + +static int tmpfs_patch_options( + const char *options, + bool userns, + uid_t uid_shift, uid_t uid_range, + bool patch_ids, + const char *selinux_apifs_context, + char **ret) { + + char *buf = NULL; + + if ((userns && uid_shift != 0) || patch_ids) { + assert(uid_shift != UID_INVALID); + + if (options) + (void) asprintf(&buf, "%s,uid=" UID_FMT ",gid=" UID_FMT, options, uid_shift, uid_shift); + else + (void) asprintf(&buf, "uid=" UID_FMT ",gid=" UID_FMT, uid_shift, uid_shift); + if (!buf) + return -ENOMEM; + + options = buf; + } + +#ifdef HAVE_SELINUX + if (selinux_apifs_context) { + char *t; + + if (options) + t = strjoin(options, ",context=\"", selinux_apifs_context, "\"", NULL); + else + t = strjoin("context=\"", selinux_apifs_context, "\"", NULL); + if (!t) { + free(buf); + return -ENOMEM; + } + + free(buf); + buf = t; + } +#endif + + if (!buf && options) { + buf = strdup(options); + if (!buf) + return -ENOMEM; + } + *ret = buf; + + return !!buf; +} + +int mount_sysfs(const char *dest) { + const char *full, *top, *x; + int r; + + top = prefix_roota(dest, "/sys"); + r = path_check_fstype(top, SYSFS_MAGIC); + if (r < 0) + return log_error_errno(r, "Failed to determine filesystem type of %s: %m", top); + /* /sys might already be mounted as sysfs by the outer child in the + * !netns case. In this case, it's all good. Don't touch it because we + * don't have the right to do so, see https://github.com/systemd/systemd/issues/1555. + */ + if (r > 0) + return 0; + + full = prefix_roota(top, "/full"); + + (void) mkdir(full, 0755); + + r = mount_verbose(LOG_ERR, "sysfs", full, "sysfs", + MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL); + if (r < 0) + return r; + + FOREACH_STRING(x, "block", "bus", "class", "dev", "devices", "kernel") { + _cleanup_free_ char *from = NULL, *to = NULL; + + from = prefix_root(full, x); + if (!from) + return log_oom(); + + to = prefix_root(top, x); + if (!to) + return log_oom(); + + (void) mkdir(to, 0755); + + r = mount_verbose(LOG_ERR, from, to, NULL, MS_BIND, NULL); + if (r < 0) + return r; + + r = mount_verbose(LOG_ERR, NULL, to, NULL, + MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, NULL); + if (r < 0) + return r; + } + + r = umount_verbose(full); + if (r < 0) + return r; + + if (rmdir(full) < 0) + return log_error_errno(errno, "Failed to remove %s: %m", full); + + x = prefix_roota(top, "/fs/kdbus"); + (void) mkdir_p(x, 0755); + + /* Create mountpoint for cgroups. Otherwise we are not allowed since we + * remount /sys read-only. + */ + if (cg_ns_supported()) { + x = prefix_roota(top, "/fs/cgroup"); + (void) mkdir_p(x, 0755); + } + + return mount_verbose(LOG_ERR, NULL, top, NULL, + MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, NULL); +} + +static int mkdir_userns(const char *path, mode_t mode, bool in_userns, uid_t uid_shift) { + int r; + + assert(path); + + r = mkdir(path, mode); + if (r < 0 && errno != EEXIST) + return -errno; + + if (!in_userns) { + r = lchown(path, uid_shift, uid_shift); + if (r < 0) + return -errno; + } + + return 0; +} + +static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, bool in_userns, uid_t uid_shift) { + const char *p, *e; + int r; + + assert(path); + + if (prefix && !path_startswith(path, prefix)) + return -ENOTDIR; + + /* create every parent directory in the path, except the last component */ + p = path + strspn(path, "/"); + for (;;) { + char t[strlen(path) + 1]; + + e = p + strcspn(p, "/"); + p = e + strspn(e, "/"); + + /* Is this the last component? If so, then we're done */ + if (*p == 0) + break; + + memcpy(t, path, e - path); + t[e-path] = 0; + + if (prefix && path_startswith(prefix, t)) + continue; + + r = mkdir_userns(t, mode, in_userns, uid_shift); + if (r < 0) + return r; + } + + return mkdir_userns(path, mode, in_userns, uid_shift); +} + +int mount_all(const char *dest, + bool use_userns, bool in_userns, + bool use_netns, + uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + + typedef struct MountPoint { + const char *what; + const char *where; + const char *type; + const char *options; + unsigned long flags; + bool fatal; + bool in_userns; + bool use_netns; + } MountPoint; + + static const MountPoint mount_table[] = { + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true, true, false }, + { "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND, true, true, false }, /* Bind mount first ...*/ + { "/proc/sys/net", "/proc/sys/net", NULL, NULL, MS_BIND, true, true, true }, /* (except for this) */ + { NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, true, true, false }, /* ... then, make it r/o */ + { "/proc/sysrq-trigger", "/proc/sysrq-trigger", NULL, NULL, MS_BIND, false, true, false }, /* Bind mount first ...*/ + { NULL, "/proc/sysrq-trigger", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, true, false }, /* ... then, make it r/o */ + { "tmpfs", "/sys", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV, true, false, true }, + { "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true, false, false }, + { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, true, false, false }, + { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true, false, false }, + { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true, false, false }, + { "tmpfs", "/tmp", "tmpfs", "mode=1777", MS_STRICTATIME, true, false, false }, +#ifdef HAVE_SELINUX + { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, false, false, false }, /* Bind mount first */ + { NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, false, false }, /* Then, make it r/o */ +#endif + }; + + unsigned k; + int r; + + for (k = 0; k < ELEMENTSOF(mount_table); k++) { + _cleanup_free_ char *where = NULL, *options = NULL; + const char *o; + + if (in_userns != mount_table[k].in_userns) + continue; + + if (!use_netns && mount_table[k].use_netns) + continue; + + where = prefix_root(dest, mount_table[k].where); + if (!where) + return log_oom(); + + r = path_is_mount_point(where, AT_SYMLINK_FOLLOW); + if (r < 0 && r != -ENOENT) + return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where); + + /* Skip this entry if it is not a remount. */ + if (mount_table[k].what && r > 0) + continue; + + r = mkdir_userns_p(dest, where, 0755, in_userns, uid_shift); + if (r < 0 && r != -EEXIST) { + if (mount_table[k].fatal) + return log_error_errno(r, "Failed to create directory %s: %m", where); + + log_debug_errno(r, "Failed to create directory %s: %m", where); + continue; + } + + o = mount_table[k].options; + if (streq_ptr(mount_table[k].type, "tmpfs")) { + if (in_userns) + r = tmpfs_patch_options(o, use_userns, 0, uid_range, true, selinux_apifs_context, &options); + else + r = tmpfs_patch_options(o, use_userns, uid_shift, uid_range, false, selinux_apifs_context, &options); + if (r < 0) + return log_oom(); + if (r > 0) + o = options; + } + + r = mount_verbose(mount_table[k].fatal ? LOG_ERR : LOG_WARNING, + mount_table[k].what, + where, + mount_table[k].type, + mount_table[k].flags, + o); + if (r < 0 && mount_table[k].fatal) + return r; + } + + return 0; +} + +static int parse_mount_bind_options(const char *options, unsigned long *mount_flags, char **mount_opts) { + const char *p = options; + unsigned long flags = *mount_flags; + char *opts = NULL; + + assert(options); + + for (;;) { + _cleanup_free_ char *word = NULL; + int r = extract_first_word(&p, &word, ",", 0); + if (r < 0) + return log_error_errno(r, "Failed to extract mount option: %m"); + if (r == 0) + break; + + if (streq(word, "rbind")) + flags |= MS_REC; + else if (streq(word, "norbind")) + flags &= ~MS_REC; + else { + log_error("Invalid bind mount option: %s", word); + return -EINVAL; + } + } + + *mount_flags = flags; + /* in the future mount_opts will hold string options for mount(2) */ + *mount_opts = opts; + + return 0; +} + +static int mount_bind(const char *dest, CustomMount *m) { + struct stat source_st, dest_st; + const char *where; + unsigned long mount_flags = MS_BIND | MS_REC; + _cleanup_free_ char *mount_opts = NULL; + int r; + + assert(m); + + if (m->options) { + r = parse_mount_bind_options(m->options, &mount_flags, &mount_opts); + if (r < 0) + return r; + } + + if (stat(m->source, &source_st) < 0) + return log_error_errno(errno, "Failed to stat %s: %m", m->source); + + where = prefix_roota(dest, m->destination); + + if (stat(where, &dest_st) >= 0) { + if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode)) { + log_error("Cannot bind mount directory %s on file %s.", m->source, where); + return -EINVAL; + } + + if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode)) { + log_error("Cannot bind mount file %s on directory %s.", m->source, where); + return -EINVAL; + } + + } else if (errno == ENOENT) { + r = mkdir_parents_label(where, 0755); + if (r < 0) + return log_error_errno(r, "Failed to make parents of %s: %m", where); + + /* Create the mount point. Any non-directory file can be + * mounted on any non-directory file (regular, fifo, socket, + * char, block). + */ + if (S_ISDIR(source_st.st_mode)) + r = mkdir_label(where, 0755); + else + r = touch(where); + if (r < 0) + return log_error_errno(r, "Failed to create mount point %s: %m", where); + + } else + return log_error_errno(errno, "Failed to stat %s: %m", where); + + r = mount_verbose(LOG_ERR, m->source, where, NULL, mount_flags, mount_opts); + if (r < 0) + return r; + + if (m->read_only) { + r = bind_remount_recursive(where, true, NULL); + if (r < 0) + return log_error_errno(r, "Read-only bind mount failed: %m"); + } + + return 0; +} + +static int mount_tmpfs( + const char *dest, + CustomMount *m, + bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + + const char *where, *options; + _cleanup_free_ char *buf = NULL; + int r; + + assert(dest); + assert(m); + + where = prefix_roota(dest, m->destination); + + r = mkdir_p_label(where, 0755); + if (r < 0 && r != -EEXIST) + return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where); + + r = tmpfs_patch_options(m->options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf); + if (r < 0) + return log_oom(); + options = r > 0 ? buf : m->options; + + return mount_verbose(LOG_ERR, "tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options); +} + +static char *joined_and_escaped_lower_dirs(char * const *lower) { + _cleanup_strv_free_ char **sv = NULL; + + sv = strv_copy(lower); + if (!sv) + return NULL; + + strv_reverse(sv); + + if (!strv_shell_escape(sv, ",:")) + return NULL; + + return strv_join(sv, ":"); +} + +static int mount_overlay(const char *dest, CustomMount *m) { + _cleanup_free_ char *lower = NULL; + const char *where, *options; + int r; + + assert(dest); + assert(m); + + where = prefix_roota(dest, m->destination); + + r = mkdir_label(where, 0755); + if (r < 0 && r != -EEXIST) + return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where); + + (void) mkdir_p_label(m->source, 0755); + + lower = joined_and_escaped_lower_dirs(m->lower); + if (!lower) + return log_oom(); + + if (m->read_only) { + _cleanup_free_ char *escaped_source = NULL; + + escaped_source = shell_escape(m->source, ",:"); + if (!escaped_source) + return log_oom(); + + options = strjoina("lowerdir=", escaped_source, ":", lower); + } else { + _cleanup_free_ char *escaped_source = NULL, *escaped_work_dir = NULL; + + assert(m->work_dir); + (void) mkdir_label(m->work_dir, 0700); + + escaped_source = shell_escape(m->source, ",:"); + if (!escaped_source) + return log_oom(); + escaped_work_dir = shell_escape(m->work_dir, ",:"); + if (!escaped_work_dir) + return log_oom(); + + options = strjoina("lowerdir=", lower, ",upperdir=", escaped_source, ",workdir=", escaped_work_dir); + } + + return mount_verbose(LOG_ERR, "overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options); +} + +int mount_custom( + const char *dest, + CustomMount *mounts, unsigned n, + bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + + unsigned i; + int r; + + assert(dest); + + for (i = 0; i < n; i++) { + CustomMount *m = mounts + i; + + switch (m->type) { + + case CUSTOM_MOUNT_BIND: + r = mount_bind(dest, m); + break; + + case CUSTOM_MOUNT_TMPFS: + r = mount_tmpfs(dest, m, userns, uid_shift, uid_range, selinux_apifs_context); + break; + + case CUSTOM_MOUNT_OVERLAY: + r = mount_overlay(dest, m); + break; + + default: + assert_not_reached("Unknown custom mount type"); + } + + if (r < 0) + return r; + } + + return 0; +} + +/* Retrieve existing subsystems. This function is called in a new cgroup + * namespace. + */ +static int get_controllers(Set *subsystems) { + _cleanup_fclose_ FILE *f = NULL; + char line[LINE_MAX]; + + assert(subsystems); + + f = fopen("/proc/self/cgroup", "re"); + if (!f) + return errno == ENOENT ? -ESRCH : -errno; + + FOREACH_LINE(line, f, return -errno) { + int r; + char *e, *l, *p; + + l = strchr(line, ':'); + if (!l) + continue; + + l++; + e = strchr(l, ':'); + if (!e) + continue; + + *e = 0; + + if (STR_IN_SET(l, "", "name=systemd")) + continue; + + p = strdup(l); + if (!p) + return -ENOMEM; + + r = set_consume(subsystems, p); + if (r < 0) + return r; + } + + return 0; +} + +static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy, + CGroupUnified unified_requested, bool read_only) { + const char *to, *fstype, *opts; + int r; + + to = strjoina(strempty(dest), "/sys/fs/cgroup/", hierarchy); + + r = path_is_mount_point(to, 0); + if (r < 0 && r != -ENOENT) + return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to); + if (r > 0) + return 0; + + mkdir_p(to, 0755); + + /* The superblock mount options of the mount point need to be + * identical to the hosts', and hence writable... */ + if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) { + if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { + fstype = "cgroup2"; + opts = NULL; + } else { + fstype = "cgroup"; + opts = "none,name=systemd,xattr"; + } + } else { + fstype = "cgroup"; + opts = controller; + } + + r = mount_verbose(LOG_ERR, "cgroup", to, fstype, MS_NOSUID|MS_NOEXEC|MS_NODEV, opts); + if (r < 0) + return r; + + /* ... hence let's only make the bind mount read-only, not the superblock. */ + if (read_only) { + r = mount_verbose(LOG_ERR, NULL, to, NULL, + MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL); + if (r < 0) + return r; + } + + return 1; +} + +/* Mount a legacy cgroup hierarchy when cgroup namespaces are supported. */ +static int mount_legacy_cgns_supported( + CGroupUnified unified_requested, bool userns, uid_t uid_shift, + uid_t uid_range, const char *selinux_apifs_context) { + _cleanup_set_free_free_ Set *controllers = NULL; + const char *cgroup_root = "/sys/fs/cgroup", *c; + int r; + + (void) mkdir_p(cgroup_root, 0755); + + /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */ + r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW); + if (r < 0) + return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m"); + if (r == 0) { + _cleanup_free_ char *options = NULL; + + /* When cgroup namespaces are enabled and user namespaces are + * used then the mount of the cgroupfs is done *inside* the new + * user namespace. We're root in the new user namespace and the + * kernel will happily translate our uid/gid to the correct + * uid/gid as seen from e.g. /proc/1/mountinfo. So we simply + * pass uid 0 and not uid_shift to tmpfs_patch_options(). + */ + r = tmpfs_patch_options("mode=755", userns, 0, uid_range, true, selinux_apifs_context, &options); + if (r < 0) + return log_oom(); + + r = mount_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", + MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); + if (r < 0) + return r; + } + + if (cg_all_unified() > 0) + goto skip_controllers; + + controllers = set_new(&string_hash_ops); + if (!controllers) + return log_oom(); + + r = get_controllers(controllers); + if (r < 0) + return log_error_errno(r, "Failed to determine cgroup controllers: %m"); + + for (;;) { + _cleanup_free_ const char *controller = NULL; + + controller = set_steal_first(controllers); + if (!controller) + break; + + r = mount_legacy_cgroup_hierarchy("", controller, controller, unified_requested, !userns); + if (r < 0) + return r; + + /* When multiple hierarchies are co-mounted, make their + * constituting individual hierarchies a symlink to the + * co-mount. + */ + c = controller; + for (;;) { + _cleanup_free_ char *target = NULL, *tok = NULL; + + r = extract_first_word(&c, &tok, ",", 0); + if (r < 0) + return log_error_errno(r, "Failed to extract co-mounted cgroup controller: %m"); + if (r == 0) + break; + + target = prefix_root("/sys/fs/cgroup", tok); + if (!target) + return log_oom(); + + if (streq(controller, tok)) + break; + + r = symlink_idempotent(controller, target); + if (r == -EINVAL) + return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m"); + if (r < 0) + return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m"); + } + } + +skip_controllers: + r = mount_legacy_cgroup_hierarchy("", SYSTEMD_CGROUP_CONTROLLER, "systemd", unified_requested, false); + if (r < 0) + return r; + + if (!userns) + return mount_verbose(LOG_ERR, NULL, cgroup_root, NULL, + MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); + + return 0; +} + +/* Mount legacy cgroup hierarchy when cgroup namespaces are unsupported. */ +static int mount_legacy_cgns_unsupported( + const char *dest, + CGroupUnified unified_requested, bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + _cleanup_set_free_free_ Set *controllers = NULL; + const char *cgroup_root; + int r; + + cgroup_root = prefix_roota(dest, "/sys/fs/cgroup"); + + (void) mkdir_p(cgroup_root, 0755); + + /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */ + r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW); + if (r < 0) + return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m"); + if (r == 0) { + _cleanup_free_ char *options = NULL; + + r = tmpfs_patch_options("mode=755", userns, uid_shift, uid_range, false, selinux_apifs_context, &options); + if (r < 0) + return log_oom(); + + r = mount_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", + MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); + if (r < 0) + return r; + } + + if (cg_all_unified() > 0) + goto skip_controllers; + + controllers = set_new(&string_hash_ops); + if (!controllers) + return log_oom(); + + r = cg_kernel_controllers(controllers); + if (r < 0) + return log_error_errno(r, "Failed to determine cgroup controllers: %m"); + + for (;;) { + _cleanup_free_ char *controller = NULL, *origin = NULL, *combined = NULL; + + controller = set_steal_first(controllers); + if (!controller) + break; + + origin = prefix_root("/sys/fs/cgroup/", controller); + if (!origin) + return log_oom(); + + r = readlink_malloc(origin, &combined); + if (r == -EINVAL) { + /* Not a symbolic link, but directly a single cgroup hierarchy */ + + r = mount_legacy_cgroup_hierarchy(dest, controller, controller, unified_requested, true); + if (r < 0) + return r; + + } else if (r < 0) + return log_error_errno(r, "Failed to read link %s: %m", origin); + else { + _cleanup_free_ char *target = NULL; + + target = prefix_root(dest, origin); + if (!target) + return log_oom(); + + /* A symbolic link, a combination of controllers in one hierarchy */ + + if (!filename_is_valid(combined)) { + log_warning("Ignoring invalid combined hierarchy %s.", combined); + continue; + } + + r = mount_legacy_cgroup_hierarchy(dest, combined, combined, unified_requested, true); + if (r < 0) + return r; + + r = symlink_idempotent(combined, target); + if (r == -EINVAL) + return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m"); + if (r < 0) + return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m"); + } + } + +skip_controllers: + r = mount_legacy_cgroup_hierarchy(dest, SYSTEMD_CGROUP_CONTROLLER, "systemd", unified_requested, false); + if (r < 0) + return r; + + return mount_verbose(LOG_ERR, NULL, cgroup_root, NULL, + MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); +} + +static int mount_unified_cgroups(const char *dest) { + const char *p; + int r; + + assert(dest); + + p = prefix_roota(dest, "/sys/fs/cgroup"); + + (void) mkdir_p(p, 0755); + + r = path_is_mount_point(p, AT_SYMLINK_FOLLOW); + if (r < 0) + return log_error_errno(r, "Failed to determine if %s is mounted already: %m", p); + if (r > 0) { + p = prefix_roota(dest, "/sys/fs/cgroup/cgroup.procs"); + if (access(p, F_OK) >= 0) + return 0; + if (errno != ENOENT) + return log_error_errno(errno, "Failed to determine if mount point %s contains the unified cgroup hierarchy: %m", p); + + log_error("%s is already mounted but not a unified cgroup hierarchy. Refusing.", p); + return -EINVAL; + } + + return mount_verbose(LOG_ERR, "cgroup", p, "cgroup2", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL); +} + +int mount_cgroups( + const char *dest, + CGroupUnified unified_requested, + bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context, + bool use_cgns) { + + if (unified_requested >= CGROUP_UNIFIED_ALL) + return mount_unified_cgroups(dest); + else if (use_cgns) + return mount_legacy_cgns_supported(unified_requested, userns, uid_shift, uid_range, selinux_apifs_context); + + return mount_legacy_cgns_unsupported(dest, unified_requested, userns, uid_shift, uid_range, selinux_apifs_context); +} + +int mount_systemd_cgroup_writable( + const char *dest, + CGroupUnified unified_requested) { + + _cleanup_free_ char *own_cgroup_path = NULL; + const char *systemd_root, *systemd_own; + int r; + + assert(dest); + + r = cg_pid_get_path(NULL, 0, &own_cgroup_path); + if (r < 0) + return log_error_errno(r, "Failed to determine our own cgroup path: %m"); + + /* If we are living in the top-level, then there's nothing to do... */ + if (path_equal(own_cgroup_path, "/")) + return 0; + + if (unified_requested >= CGROUP_UNIFIED_ALL) { + systemd_own = strjoina(dest, "/sys/fs/cgroup", own_cgroup_path); + systemd_root = prefix_roota(dest, "/sys/fs/cgroup"); + } else { + systemd_own = strjoina(dest, "/sys/fs/cgroup/systemd", own_cgroup_path); + systemd_root = prefix_roota(dest, "/sys/fs/cgroup/systemd"); + } + + /* Make our own cgroup a (writable) bind mount */ + r = mount_verbose(LOG_ERR, systemd_own, systemd_own, NULL, MS_BIND, NULL); + if (r < 0) + return r; + + /* And then remount the systemd cgroup root read-only */ + return mount_verbose(LOG_ERR, NULL, systemd_root, NULL, + MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL); +} + +int setup_volatile_state( + const char *directory, + VolatileMode mode, + bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + + _cleanup_free_ char *buf = NULL; + const char *p, *options; + int r; + + assert(directory); + + if (mode != VOLATILE_STATE) + return 0; + + /* --volatile=state means we simply overmount /var + with a tmpfs, and the rest read-only. */ + + r = bind_remount_recursive(directory, true, NULL); + if (r < 0) + return log_error_errno(r, "Failed to remount %s read-only: %m", directory); + + p = prefix_roota(directory, "/var"); + r = mkdir(p, 0755); + if (r < 0 && errno != EEXIST) + return log_error_errno(errno, "Failed to create %s: %m", directory); + + options = "mode=755"; + r = tmpfs_patch_options(options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf); + if (r < 0) + return log_oom(); + if (r > 0) + options = buf; + + return mount_verbose(LOG_ERR, "tmpfs", p, "tmpfs", MS_STRICTATIME, options); +} + +int setup_volatile( + const char *directory, + VolatileMode mode, + bool userns, uid_t uid_shift, uid_t uid_range, + const char *selinux_apifs_context) { + + bool tmpfs_mounted = false, bind_mounted = false; + char template[] = "/tmp/nspawn-volatile-XXXXXX"; + _cleanup_free_ char *buf = NULL; + const char *f, *t, *options; + int r; + + assert(directory); + + if (mode != VOLATILE_YES) + return 0; + + /* --volatile=yes means we mount a tmpfs to the root dir, and + the original /usr to use inside it, and that read-only. */ + + if (!mkdtemp(template)) + return log_error_errno(errno, "Failed to create temporary directory: %m"); + + options = "mode=755"; + r = tmpfs_patch_options(options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf); + if (r < 0) + return log_oom(); + if (r > 0) + options = buf; + + r = mount_verbose(LOG_ERR, "tmpfs", template, "tmpfs", MS_STRICTATIME, options); + if (r < 0) + goto fail; + + tmpfs_mounted = true; + + f = prefix_roota(directory, "/usr"); + t = prefix_roota(template, "/usr"); + + r = mkdir(t, 0755); + if (r < 0 && errno != EEXIST) { + r = log_error_errno(errno, "Failed to create %s: %m", t); + goto fail; + } + + r = mount_verbose(LOG_ERR, f, t, NULL, MS_BIND|MS_REC, NULL); + if (r < 0) + goto fail; + + bind_mounted = true; + + r = bind_remount_recursive(t, true, NULL); + if (r < 0) { + log_error_errno(r, "Failed to remount %s read-only: %m", t); + goto fail; + } + + r = mount_verbose(LOG_ERR, template, directory, NULL, MS_MOVE, NULL); + if (r < 0) + goto fail; + + (void) rmdir(template); + + return 0; + +fail: + if (bind_mounted) + (void) umount_verbose(t); + + if (tmpfs_mounted) + (void) umount_verbose(template); + (void) rmdir(template); + return r; +} + +VolatileMode volatile_mode_from_string(const char *s) { + int b; + + if (isempty(s)) + return _VOLATILE_MODE_INVALID; + + b = parse_boolean(s); + if (b > 0) + return VOLATILE_YES; + if (b == 0) + return VOLATILE_NO; + + if (streq(s, "state")) + return VOLATILE_STATE; + + return _VOLATILE_MODE_INVALID; +} |