| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <sys/mount.h> |
| |
| #include "alloc-util.h" |
| #include "cgroup-setup.h" |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "format-util.h" |
| #include "fs-util.h" |
| #include "mkdir.h" |
| #include "mount-util.h" |
| #include "mountpoint-util.h" |
| #include "nspawn-cgroup.h" |
| #include "nspawn-mount.h" |
| #include "path-util.h" |
| #include "rm-rf.h" |
| #include "string-util.h" |
| #include "strv.h" |
| #include "user-util.h" |
| |
| static int chown_cgroup_path(const char *path, uid_t uid_shift) { |
| _cleanup_close_ int fd = -EBADF; |
| |
| fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY); |
| if (fd < 0) |
| return -errno; |
| |
| FOREACH_STRING(fn, |
| ".", |
| "cgroup.clone_children", |
| "cgroup.controllers", |
| "cgroup.events", |
| "cgroup.procs", |
| "cgroup.stat", |
| "cgroup.subtree_control", |
| "cgroup.threads", |
| "notify_on_release", |
| "tasks") |
| if (fchownat(fd, fn, uid_shift, uid_shift, 0) < 0) |
| log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno, |
| "Failed to chown \"%s/%s\", ignoring: %m", path, fn); |
| |
| return 0; |
| } |
| |
| int chown_cgroup(pid_t pid, CGroupUnified unified_requested, uid_t uid_shift) { |
| _cleanup_free_ char *path = NULL, *fs = NULL; |
| int r; |
| |
| r = cg_pid_get_path(NULL, pid, &path); |
| if (r < 0) |
| return log_error_errno(r, "Failed to get container cgroup path: %m"); |
| |
| r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &fs); |
| if (r < 0) |
| return log_error_errno(r, "Failed to get file system path for container cgroup: %m"); |
| |
| r = chown_cgroup_path(fs, uid_shift); |
| if (r < 0) |
| return log_error_errno(r, "Failed to chown() cgroup %s: %m", fs); |
| |
| if (unified_requested == CGROUP_UNIFIED_SYSTEMD || (unified_requested == CGROUP_UNIFIED_NONE && cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) > 0)) { |
| _cleanup_free_ char *lfs = NULL; |
| /* Always propagate access rights from unified to legacy controller */ |
| |
| r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path, NULL, &lfs); |
| if (r < 0) |
| return log_error_errno(r, "Failed to get file system path for container cgroup: %m"); |
| |
| r = chown_cgroup_path(lfs, uid_shift); |
| if (r < 0) |
| return log_error_errno(r, "Failed to chown() cgroup %s: %m", lfs); |
| } |
| |
| return 0; |
| } |
| |
| int sync_cgroup(pid_t pid, CGroupUnified unified_requested, uid_t uid_shift) { |
| _cleanup_free_ char *cgroup = NULL; |
| char tree[] = "/tmp/unifiedXXXXXX", pid_string[DECIMAL_STR_MAX(pid) + 1]; |
| bool undo_mount = false; |
| const char *fn; |
| int r, unified_controller; |
| |
| unified_controller = cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER); |
| if (unified_controller < 0) |
| return log_error_errno(unified_controller, "Failed to determine whether the systemd hierarchy is unified: %m"); |
| if ((unified_controller > 0) == (unified_requested >= CGROUP_UNIFIED_SYSTEMD)) |
| return 0; |
| |
| /* When the host uses the legacy cgroup setup, but the |
| * container shall use the unified hierarchy, let's make sure |
| * we copy the path from the name=systemd hierarchy into the |
| * unified hierarchy. Similar for the reverse situation. */ |
| |
| r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &cgroup); |
| if (r < 0) |
| return log_error_errno(r, "Failed to get control group of " PID_FMT ": %m", pid); |
| |
| /* In order to access the unified hierarchy we need to mount it */ |
| if (!mkdtemp(tree)) |
| return log_error_errno(errno, "Failed to generate temporary mount point for unified hierarchy: %m"); |
| |
| if (unified_controller > 0) |
| r = mount_nofollow_verbose(LOG_ERR, "cgroup", tree, "cgroup", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV, "none,name=systemd,xattr"); |
| else |
| r = mount_nofollow_verbose(LOG_ERR, "cgroup", tree, "cgroup2", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL); |
| if (r < 0) |
| goto finish; |
| |
| undo_mount = true; |
| |
| /* If nspawn dies abruptly the cgroup hierarchy created below |
| * its unit isn't cleaned up. So, let's remove it |
| * https://github.com/systemd/systemd/pull/4223#issuecomment-252519810 */ |
| fn = strjoina(tree, cgroup); |
| (void) rm_rf(fn, REMOVE_ROOT|REMOVE_ONLY_DIRECTORIES); |
| |
| fn = strjoina(tree, cgroup, "/cgroup.procs"); |
| |
| sprintf(pid_string, PID_FMT, pid); |
| r = write_string_file(fn, pid_string, WRITE_STRING_FILE_DISABLE_BUFFER|WRITE_STRING_FILE_MKDIR_0755); |
| if (r < 0) { |
| log_error_errno(r, "Failed to move process: %m"); |
| goto finish; |
| } |
| |
| fn = strjoina(tree, cgroup); |
| r = chown_cgroup_path(fn, uid_shift); |
| if (r < 0) |
| log_error_errno(r, "Failed to chown() cgroup %s: %m", fn); |
| finish: |
| if (undo_mount) |
| (void) umount_verbose(LOG_ERR, tree, UMOUNT_NOFOLLOW); |
| |
| (void) rmdir(tree); |
| return r; |
| } |
| |
| int create_subcgroup(pid_t pid, bool keep_unit, CGroupUnified unified_requested) { |
| _cleanup_free_ char *cgroup = NULL; |
| CGroupMask supported; |
| const char *payload; |
| int r; |
| |
| assert(pid > 1); |
| |
| /* In the unified hierarchy inner nodes may only contain subgroups, but not processes. Hence, if we running in |
| * the unified hierarchy and the container does the same, and we did not create a scope unit for the container |
| * move us and the container into two separate subcgroups. |
| * |
| * Moreover, container payloads such as systemd try to manage the cgroup they run in full (i.e. including |
| * its attributes), while the host systemd will only delegate cgroups for children of the cgroup created for a |
| * delegation unit, instead of the cgroup itself. This means, if we'd pass on the cgroup allocated from the |
| * host systemd directly to the payload, the host and payload systemd might fight for the cgroup |
| * attributes. Hence, let's insert an intermediary cgroup to cover that case too. |
| * |
| * Note that we only bother with the main hierarchy here, not with any secondary ones. On the unified setup |
| * that's fine because there's only one hierarchy anyway and controllers are enabled directly on it. On the |
| * legacy setup, this is fine too, since delegation of controllers is generally not safe there, hence we won't |
| * do it. */ |
| |
| r = cg_mask_supported(&supported); |
| if (r < 0) |
| return log_error_errno(r, "Failed to determine supported controllers: %m"); |
| |
| if (keep_unit) |
| r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup); |
| else |
| r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &cgroup); |
| if (r < 0) |
| return log_error_errno(r, "Failed to get our control group: %m"); |
| |
| payload = strjoina(cgroup, "/payload"); |
| r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, payload, pid); |
| if (r < 0) |
| return log_error_errno(r, "Failed to create %s subcgroup: %m", payload); |
| |
| if (keep_unit) { |
| const char *supervisor; |
| |
| supervisor = strjoina(cgroup, "/supervisor"); |
| r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, supervisor, 0); |
| if (r < 0) |
| return log_error_errno(r, "Failed to create %s subcgroup: %m", supervisor); |
| } |
| |
| /* Try to enable as many controllers as possible for the new payload. */ |
| (void) cg_enable_everywhere(supported, supported, cgroup, NULL); |
| return 0; |
| } |
| |
| /* Retrieve existing subsystems. This function is called in a new cgroup |
| * namespace. |
| */ |
| static int get_process_controllers(Set **ret) { |
| _cleanup_set_free_ Set *controllers = NULL; |
| _cleanup_fclose_ FILE *f = NULL; |
| int r; |
| |
| assert(ret); |
| |
| f = fopen("/proc/self/cgroup", "re"); |
| if (!f) |
| return errno == ENOENT ? -ESRCH : -errno; |
| |
| for (;;) { |
| _cleanup_free_ char *line = NULL; |
| char *e, *l; |
| |
| r = read_line(f, LONG_LINE_MAX, &line); |
| if (r < 0) |
| return r; |
| if (r == 0) |
| break; |
| |
| l = strchr(line, ':'); |
| if (!l) |
| continue; |
| |
| l++; |
| e = strchr(l, ':'); |
| if (!e) |
| continue; |
| |
| *e = 0; |
| |
| if (STR_IN_SET(l, "", "name=systemd", "name=unified")) |
| continue; |
| |
| r = set_put_strdup(&controllers, l); |
| if (r < 0) |
| return r; |
| } |
| |
| *ret = TAKE_PTR(controllers); |
| |
| return 0; |
| } |
| |
| static int mount_legacy_cgroup_hierarchy( |
| const char *dest, |
| const char *controller, |
| const char *hierarchy, |
| bool read_only) { |
| |
| const char *to, *fstype, *opts; |
| int r; |
| |
| to = strjoina(strempty(dest), "/sys/fs/cgroup/", hierarchy); |
| |
| r = path_is_mount_point(to, dest, 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; |
| |
| (void) 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_HYBRID)) { |
| fstype = "cgroup2"; |
| opts = NULL; |
| } else if (streq(controller, SYSTEMD_CGROUP_CONTROLLER_LEGACY)) { |
| fstype = "cgroup"; |
| opts = "none,name=systemd,xattr"; |
| } else { |
| fstype = "cgroup"; |
| opts = controller; |
| } |
| |
| r = mount_nofollow_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_nofollow_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( |
| const char *dest, |
| CGroupUnified unified_requested, |
| bool userns, |
| uid_t uid_shift, |
| uid_t uid_range, |
| const char *selinux_apifs_context) { |
| |
| _cleanup_set_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, dest, 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=0755" TMPFS_LIMITS_SYS_FS_CGROUP, 0, selinux_apifs_context, &options); |
| if (r < 0) |
| return log_oom(); |
| |
| r = mount_nofollow_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); |
| if (r < 0) |
| return r; |
| } |
| |
| r = cg_all_unified(); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| goto skip_controllers; |
| |
| r = get_process_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, !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; |
| |
| if (streq(controller, tok)) |
| break; |
| |
| target = path_join("/sys/fs/cgroup/", tok); |
| if (!target) |
| return log_oom(); |
| |
| r = symlink_idempotent(controller, target, false); |
| 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: |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| r = mount_legacy_cgroup_hierarchy("", SYSTEMD_CGROUP_CONTROLLER_HYBRID, "unified", false); |
| if (r < 0) |
| return r; |
| } |
| |
| r = mount_legacy_cgroup_hierarchy("", SYSTEMD_CGROUP_CONTROLLER_LEGACY, "systemd", false); |
| if (r < 0) |
| return r; |
| |
| if (!userns) |
| return mount_nofollow_verbose(LOG_ERR, NULL, cgroup_root, NULL, |
| MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, |
| "mode=0755"); |
| |
| 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_ 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, dest, 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=0755" TMPFS_LIMITS_SYS_FS_CGROUP, |
| uid_shift == 0 ? UID_INVALID : uid_shift, |
| selinux_apifs_context, |
| &options); |
| if (r < 0) |
| return log_oom(); |
| |
| r = mount_nofollow_verbose(LOG_ERR, "tmpfs", cgroup_root, "tmpfs", |
| MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options); |
| if (r < 0) |
| return r; |
| } |
| |
| r = cg_all_unified(); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| goto skip_controllers; |
| |
| 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 = path_join("/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, 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 = path_join(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, true); |
| if (r < 0) |
| return r; |
| |
| r = symlink_idempotent(combined, target, false); |
| 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: |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| r = mount_legacy_cgroup_hierarchy(dest, SYSTEMD_CGROUP_CONTROLLER_HYBRID, "unified", false); |
| if (r < 0) |
| return r; |
| } |
| |
| r = mount_legacy_cgroup_hierarchy(dest, SYSTEMD_CGROUP_CONTROLLER_LEGACY, "systemd", false); |
| if (r < 0) |
| return r; |
| |
| return mount_nofollow_verbose(LOG_ERR, NULL, cgroup_root, NULL, |
| MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, |
| "mode=0755"); |
| } |
| |
| 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, dest, 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); |
| |
| return log_error_errno(SYNTHETIC_ERRNO(EINVAL), |
| "%s is already mounted but not a unified cgroup hierarchy. Refusing.", p); |
| } |
| |
| return mount_nofollow_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); |
| if (use_cgns) |
| return mount_legacy_cgns_supported(dest, 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); |
| } |
| |
| static int mount_systemd_cgroup_writable_one(const char *root, const char *own) { |
| int r; |
| |
| assert(root); |
| assert(own); |
| |
| /* Make our own cgroup a (writable) bind mount */ |
| r = mount_nofollow_verbose(LOG_ERR, own, own, NULL, MS_BIND, NULL); |
| if (r < 0) |
| return r; |
| |
| /* And then remount the systemd cgroup root read-only */ |
| return mount_nofollow_verbose(LOG_ERR, NULL, root, NULL, |
| MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL); |
| } |
| |
| int mount_systemd_cgroup_writable( |
| const char *dest, |
| CGroupUnified unified_requested) { |
| |
| _cleanup_free_ char *own_cgroup_path = NULL; |
| const char *root, *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) { |
| |
| root = prefix_roota(dest, "/sys/fs/cgroup"); |
| own = strjoina(root, own_cgroup_path); |
| |
| } else { |
| |
| if (unified_requested >= CGROUP_UNIFIED_SYSTEMD) { |
| root = prefix_roota(dest, "/sys/fs/cgroup/unified"); |
| own = strjoina(root, own_cgroup_path); |
| |
| r = mount_systemd_cgroup_writable_one(root, own); |
| if (r < 0) |
| return r; |
| } |
| |
| root = prefix_roota(dest, "/sys/fs/cgroup/systemd"); |
| own = strjoina(root, own_cgroup_path); |
| } |
| |
| return mount_systemd_cgroup_writable_one(root, own); |
| } |
