diff options
Diffstat (limited to 'src/nspawn/nspawn.c')
| -rw-r--r-- | src/nspawn/nspawn.c | 130 |
1 files changed, 124 insertions, 6 deletions
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 6aaceac30b..1ac0a7008c 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -869,6 +869,112 @@ static int mount_binds(const char *dest, char **l, bool ro) { return 0; } +static int mount_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy, bool read_only) { + char *to; + int r; + + to = strappenda(dest, "/sys/fs/cgroup/", hierarchy); + + r = path_is_mount_point(to, false); + if (r < 0) + return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to); + if (r > 0) + return 0; + + mkdir_p(to, 0755); + + if (mount("cgroup", to, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV|(read_only ? MS_RDONLY : 0), controller) < 0) + return log_error_errno(errno, "Failed to mount to %s: %m", to); + + return 1; +} + +static int mount_cgroup(const char *dest) { + _cleanup_set_free_free_ Set *controllers = NULL; + _cleanup_free_ char *own_cgroup_path = NULL; + const char *cgroup_root, *systemd_root, *systemd_own; + int r; + + 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"); + + 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"); + + cgroup_root = strappenda(dest, "/sys/fs/cgroup"); + if (mount("tmpfs", cgroup_root, "tmpfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, "mode=755") < 0) + return log_error_errno(errno, "Failed to mount tmpfs to /sys/fs/cgroup: %m"); + + for (;;) { + _cleanup_free_ char *controller = NULL, *origin = NULL, *combined = NULL; + + controller = set_steal_first(controllers); + if (!controller) + break; + + origin = strappend("/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_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 = strjoin(dest, "/sys/fs/cgroup/", controller, NULL); + 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_cgroup_hierarchy(dest, combined, combined, true); + if (r < 0) + return r; + + if (symlink(combined, target) < 0) + return log_error_errno(errno, "Failed to create symlink for combined hiearchy: %m"); + } + } + + r = mount_cgroup_hierarchy(dest, "name=systemd", "systemd", false); + if (r < 0) + return r; + + /* Make our own cgroup a (writable) bind mount */ + systemd_own = strappenda(dest, "/sys/fs/cgroup/systemd", own_cgroup_path); + if (mount(systemd_own, systemd_own, NULL, MS_BIND, NULL) < 0) + return log_error_errno(errno, "Failed to turn %s into a bind mount: %m", own_cgroup_path); + + /* And then remount the systemd cgroup root read-only */ + systemd_root = strappenda(dest, "/sys/fs/cgroup/systemd"); + if (mount(NULL, systemd_root, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0) + return log_error_errno(errno, "Failed to mount cgroup root read-only: %m"); + + if (mount(NULL, cgroup_root, NULL, MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755") < 0) + return log_error_errno(errno, "Failed to remount %s read-only: %m", cgroup_root); + + return 0; +} + static int mount_tmpfs(const char *dest) { char **i, **o; @@ -3309,6 +3415,11 @@ int main(int argc, char *argv[]) { kmsg_socket_pair[1] = safe_close(kmsg_socket_pair[1]); + /* Tell the parent that we are ready, and that + * it can cgroupify us to that we lack access + * to certain devices and resources. */ + (void) barrier_place(&barrier); + if (setup_boot_id(arg_directory) < 0) _exit(EXIT_FAILURE); @@ -3330,10 +3441,12 @@ int main(int argc, char *argv[]) { if (mount_tmpfs(arg_directory) < 0) _exit(EXIT_FAILURE); - /* Tell the parent that we are ready, and that - * it can cgroupify us to that we lack access - * to certain devices and resources. */ - (void)barrier_place(&barrier); + /* Wait until we are cgroup-ified, so that we + * can mount the right cgroup path writable */ + (void) barrier_sync_next(&barrier); + + if (mount_cgroup(arg_directory) < 0) + _exit(EXIT_FAILURE); if (chdir(arg_directory) < 0) { log_error_errno(errno, "chdir(%s) failed: %m", arg_directory); @@ -3472,8 +3585,10 @@ int main(int argc, char *argv[]) { fdset_free(fds); fds = NULL; - /* wait for child-setup to be done */ - if (barrier_place_and_sync(&barrier)) { + /* Wait for the most basic Child-setup to be done, + * before we add hardware to it, and place it in a + * cgroup. */ + if (barrier_sync_next(&barrier)) { _cleanup_event_unref_ sd_event *event = NULL; _cleanup_(pty_forward_freep) PTYForward *forward = NULL; char last_char = 0; @@ -3515,6 +3630,9 @@ int main(int argc, char *argv[]) { * control to the code to run inside the container. */ (void) barrier_place(&barrier); + /* And wait that the child is completely ready now. */ + (void) barrier_place_and_sync(&barrier); + sd_notify(false, "READY=1\n" "STATUS=Container running."); |