X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;ds=sidebyside;f=src%2Fnspawn%2Fnspawn.c;h=edad1cbf423b9ef9ce9eb847d7de47d7d589158a;hb=b1a5a9989ada9b3738d71605f051ff393d41f2ff;hp=0a8dc0cf301cd7bf047487e75fed5cc33db06c44;hpb=971ff8c78b3a7d94ed2289077f856c6988d18183;p=elogind.git diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 0a8dc0cf3..edad1cbf4 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -107,6 +107,12 @@ typedef enum LinkJournal { LINK_GUEST } LinkJournal; +typedef enum Volatile { + VOLATILE_NO, + VOLATILE_YES, + VOLATILE_STATE, +} Volatile; + static char *arg_directory = NULL; static char *arg_user = NULL; static sd_id128_t arg_uuid = {}; @@ -159,6 +165,7 @@ static bool arg_network_veth = false; static const char *arg_network_bridge = NULL; static unsigned long arg_personality = 0xffffffffLU; static const char *arg_image = NULL; +static Volatile arg_volatile = VOLATILE_NO; static int help(void) { @@ -207,7 +214,8 @@ static int help(void) { " --share-system Share system namespaces with host\n" " --register=BOOLEAN Register container as machine\n" " --keep-unit Do not register a scope for the machine, reuse\n" - " the service unit nspawn is running in\n", + " the service unit nspawn is running in\n" + " --volatile[=MODE] Run the system in volatile mode\n", program_invocation_short_name); return 0; @@ -235,6 +243,7 @@ static int parse_argv(int argc, char *argv[]) { ARG_NETWORK_VETH, ARG_NETWORK_BRIDGE, ARG_PERSONALITY, + ARG_VOLATILE, }; static const struct option options[] = { @@ -267,6 +276,7 @@ static int parse_argv(int argc, char *argv[]) { { "network-bridge", required_argument, NULL, ARG_NETWORK_BRIDGE }, { "personality", required_argument, NULL, ARG_PERSONALITY }, { "image", required_argument, NULL, 'i' }, + { "volatile", optional_argument, NULL, ARG_VOLATILE }, {} }; @@ -559,6 +569,25 @@ static int parse_argv(int argc, char *argv[]) { break; + case ARG_VOLATILE: + + if (!optarg) + arg_volatile = VOLATILE_YES; + else { + r = parse_boolean(optarg); + if (r < 0) { + if (streq(optarg, "state")) + arg_volatile = VOLATILE_STATE; + else { + log_error("Failed to parse --volatile= argument: %s", optarg); + return r; + } + } else + arg_volatile = r ? VOLATILE_YES : VOLATILE_NO; + } + + break; + case '?': return -EINVAL; @@ -585,6 +614,11 @@ static int parse_argv(int argc, char *argv[]) { return -EINVAL; } + if (arg_volatile != VOLATILE_NO && arg_read_only) { + log_error("Cannot combine --read-only with --volatile. Note that --volatile already implies a read-only base hierarchy."); + return -EINVAL; + } + arg_retain = (arg_retain | plus | (arg_private_network ? 1ULL << CAP_NET_ADMIN : 0)) & ~minus; return 1; @@ -712,7 +746,7 @@ static int mount_binds(const char *dest, char **l, bool ro) { } /* Create the mount point, but be conservative -- refuse to create block - * and char devices. */ + * and char devices. */ if (S_ISDIR(source_st.st_mode)) mkdir_label(where, 0755); else if (S_ISFIFO(source_st.st_mode)) @@ -796,7 +830,6 @@ static int setup_timezone(const char *dest) { if (!y) y = path_startswith(q, "/usr/share/zoneinfo/"); - /* Already pointing to the right place? Then do nothing .. */ if (y && streq(y, z)) return 0; @@ -815,7 +848,9 @@ static int setup_timezone(const char *dest) { if (!what) return log_oom(); + mkdir_parents(where, 0755); unlink(where); + if (symlink(what, where) < 0) { log_error("Failed to correct timezone of container: %m"); return 0; @@ -839,11 +874,105 @@ static int setup_resolv_conf(const char *dest) { /* We don't really care for the results of this really. If it * fails, it fails, but meh... */ + mkdir_parents(where, 0755); copy_file("/etc/resolv.conf", where, O_TRUNC|O_NOFOLLOW, 0644); return 0; } +static int setup_volatile_state(const char *directory) { + const char *p; + int r; + + assert(directory); + + if (arg_volatile != 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); + if (r < 0) { + log_error("Failed to remount %s read-only: %s", directory, strerror(-r)); + return r; + } + + p = strappenda(directory, "/var"); + mkdir(p, 0755); + + if (mount("tmpfs", p, "tmpfs", MS_STRICTATIME, "mode=755") < 0) { + log_error("Failed to mount tmpfs to /var: %m"); + return -errno; + } + + return 0; +} + +static int setup_volatile(const char *directory) { + bool tmpfs_mounted = false, bind_mounted = false; + char template[] = "/tmp/nspawn-volatile-XXXXXX"; + const char *f, *t; + int r; + + assert(directory); + + if (arg_volatile != 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)) { + log_error("Failed to create temporary directory: %m"); + return -errno; + } + + if (mount("tmpfs", template, "tmpfs", MS_STRICTATIME, "mode=755") < 0) { + log_error("Failed to mount tmpfs for root directory: %m"); + r = -errno; + goto fail; + } + + tmpfs_mounted = true; + + f = strappenda(directory, "/usr"); + t = strappenda(template, "/usr"); + + mkdir(t, 0755); + if (mount(f, t, "bind", MS_BIND|MS_REC, NULL) < 0) { + log_error("Failed to create /usr bind mount: %m"); + r = -errno; + goto fail; + } + + bind_mounted = true; + + r = bind_remount_recursive(t, true); + if (r < 0) { + log_error("Failed to remount %s read-only: %s", t, strerror(-r)); + goto fail; + } + + if (mount(template, directory, NULL, MS_MOVE, NULL) < 0) { + log_error("Failed to move root mount: %m"); + r = -errno; + goto fail; + } + + rmdir(template); + + return 0; + +fail: + if (bind_mounted) + umount(t); + if (tmpfs_mounted) + umount(template); + rmdir(template); + return r; +} + static char* id128_format_as_uuid(sd_id128_t id, char s[37]) { snprintf(s, 37, @@ -1864,22 +1993,25 @@ static int setup_macvlan(pid_t pid) { return 0; } -static int audit_still_doesnt_work_in_containers(void) { +static int setup_seccomp(void) { #ifdef HAVE_SECCOMP + static const int blacklist[] = { + SCMP_SYS(kexec_load), + SCMP_SYS(open_by_handle_at), + SCMP_SYS(init_module), + SCMP_SYS(finit_module), + SCMP_SYS(delete_module), + SCMP_SYS(iopl), + SCMP_SYS(ioperm), + SCMP_SYS(swapon), + SCMP_SYS(swapoff), + }; + scmp_filter_ctx seccomp; + unsigned i; int r; - /* - Audit is broken in containers, much of the userspace audit - hookup will fail if running inside a container. We don't - care and just turn off creation of audit sockets. - - This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail - with EAFNOSUPPORT which audit userspace uses as indication - that audit is disabled in the kernel. - */ - seccomp = seccomp_init(SCMP_ACT_ALLOW); if (!seccomp) return log_oom(); @@ -1890,6 +2022,26 @@ static int audit_still_doesnt_work_in_containers(void) { goto finish; } + for (i = 0; i < ELEMENTSOF(blacklist); i++) { + r = seccomp_rule_add(seccomp, SCMP_ACT_ERRNO(EPERM), blacklist[i], 0); + if (r == -EFAULT) + continue; /* unknown syscall */ + if (r < 0) { + log_error("Failed to block syscall: %s", strerror(-r)); + goto finish; + } + } + + /* + Audit is broken in containers, much of the userspace audit + hookup will fail if running inside a container. We don't + care and just turn off creation of audit sockets. + + This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail + with EAFNOSUPPORT which audit userspace uses as indication + that audit is disabled in the kernel. + */ + r = seccomp_rule_add( seccomp, SCMP_ACT_ERRNO(EAFNOSUPPORT), @@ -2645,20 +2797,31 @@ static int change_uid_gid(char **_home) { } /* - * Return 0 in case the container is being rebooted, has been shut - * down or exited successfully. On failures a negative value is - * returned. + * Return values: + * < 0 : wait_for_terminate() failed to get the state of the + * container, the container was terminated by a signal, or + * failed for an unknown reason. No change is made to the + * container argument. + * > 0 : The program executed in the container terminated with an + * error. The exit code of the program executed in the + * container is returned. No change is made to the container + * argument. + * 0 : The container is being rebooted, has been shut down or exited + * successfully. The container argument has been set to either + * CONTAINER_TERMINATED or CONTAINER_REBOOTED. * - * The status of the container "CONTAINER_TERMINATED" or - * "CONTAINER_REBOOTED" will be saved in the container argument + * That is, success is indicated by a return value of zero, and an + * error is indicated by a non-zero value. */ static int wait_for_container(pid_t pid, ContainerStatus *container) { int r; siginfo_t status; r = wait_for_terminate(pid, &status); - if (r < 0) + if (r < 0) { + log_warning("Failed to wait for container: %s", strerror(-r)); return r; + } switch (status.si_code) { case CLD_EXITED: @@ -2672,7 +2835,6 @@ static int wait_for_container(pid_t pid, ContainerStatus *container) { } else { log_error("Container %s failed with error code %i.", arg_machine, status.si_status); - r = -1; } break; @@ -2835,7 +2997,11 @@ int main(int argc, char *argv[]) { goto finish; } - r = dissect_image(image_fd, &root_device, &root_device_rw, &home_device, &home_device_rw, &srv_device, &srv_device_rw, &secondary); + r = dissect_image(image_fd, + &root_device, &root_device_rw, + &home_device, &home_device_rw, + &srv_device, &srv_device_rw, + &secondary); if (r < 0) goto finish; } @@ -3009,18 +3175,23 @@ int main(int argc, char *argv[]) { srv_device, srv_device_rw) < 0) goto child_fail; - r = base_filesystem_create(arg_directory); - if (r < 0) { - log_error("Failed to create the base filesystem: %s", strerror(-r)); - goto child_fail; - } - /* Turn directory into bind mount */ if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REC, NULL) < 0) { log_error("Failed to make bind mount: %m"); goto child_fail; } + r = setup_volatile(arg_directory); + if (r < 0) + goto child_fail; + + if (setup_volatile_state(arg_directory) < 0) + goto child_fail; + + r = base_filesystem_create(arg_directory); + if (r < 0) + goto child_fail; + if (arg_read_only) { k = bind_remount_recursive(arg_directory, true); if (k < 0) { @@ -3040,7 +3211,7 @@ int main(int argc, char *argv[]) { dev_setup(arg_directory); - if (audit_still_doesnt_work_in_containers() < 0) + if (setup_seccomp() < 0) goto child_fail; if (setup_dev_console(arg_directory, console) < 0) @@ -3237,75 +3408,93 @@ int main(int argc, char *argv[]) { * join its cgroup which might limit what it can do */ r = eventfd_child_succeeded(eventfds[1]); eventfds[1] = safe_close(eventfds[1]); - if (r < 0) - goto check_container_status; - r = register_machine(pid); - if (r < 0) - goto finish; + if (r >= 0) { + r = register_machine(pid); + if (r < 0) + goto finish; - r = move_network_interfaces(pid); - if (r < 0) - goto finish; + r = move_network_interfaces(pid); + if (r < 0) + goto finish; - r = setup_veth(pid, veth_name); - if (r < 0) - goto finish; + r = setup_veth(pid, veth_name); + if (r < 0) + goto finish; - r = setup_bridge(veth_name); - if (r < 0) - goto finish; + r = setup_bridge(veth_name); + if (r < 0) + goto finish; - r = setup_macvlan(pid); - if (r < 0) - goto finish; + r = setup_macvlan(pid); + if (r < 0) + goto finish; - /* Block SIGCHLD here, before notifying child. - * process_pty() will handle it with the other signals. */ - r = sigprocmask(SIG_BLOCK, &mask_chld, NULL); - if (r < 0) - goto finish; + /* Block SIGCHLD here, before notifying child. + * process_pty() will handle it with the other signals. */ + r = sigprocmask(SIG_BLOCK, &mask_chld, NULL); + if (r < 0) + goto finish; - /* Reset signal to default */ - r = default_signals(SIGCHLD, -1); - if (r < 0) - goto finish; + /* Reset signal to default */ + r = default_signals(SIGCHLD, -1); + if (r < 0) + goto finish; - /* Notify the child that the parent is ready with all - * its setup, and that the child can now hand over - * control to the code to run inside the container. */ - r = eventfd_send_state(eventfds[0], - EVENTFD_PARENT_SUCCEEDED); - eventfds[0] = safe_close(eventfds[0]); - if (r < 0) - goto finish; + /* Notify the child that the parent is ready with all + * its setup, and that the child can now hand over + * control to the code to run inside the container. */ + r = eventfd_send_state(eventfds[0], EVENTFD_PARENT_SUCCEEDED); + eventfds[0] = safe_close(eventfds[0]); + if (r < 0) + goto finish; - k = process_pty(master, &mask, arg_boot ? pid : 0, SIGRTMIN+3); - if (k < 0) { - r = EXIT_FAILURE; - break; - } + k = process_pty(master, &mask, arg_boot ? pid : 0, SIGRTMIN+3); + if (k < 0) { + r = EXIT_FAILURE; + break; + } - if (!arg_quiet) - putc('\n', stdout); + if (!arg_quiet) + putc('\n', stdout); - /* Kill if it is not dead yet anyway */ - terminate_machine(pid); + /* Kill if it is not dead yet anyway */ + terminate_machine(pid); + } -check_container_status: - /* Redundant, but better safe than sorry */ + /* Normally redundant, but better safe than sorry */ kill(pid, SIGKILL); r = wait_for_container(pid, &container_status); pid = 0; if (r < 0) { + /* We failed to wait for the container, or the + * container exited abnormally */ r = EXIT_FAILURE; break; - } else if (container_status == CONTAINER_TERMINATED) + } else if (r > 0 || container_status == CONTAINER_TERMINATED) + /* The container exited with a non-zero + * status, or with zero status and no reboot + * was requested. */ break; /* CONTAINER_REBOOTED, loop again */ + + if (arg_keep_unit) { + /* Special handling if we are running as a + * service: instead of simply restarting the + * machine we want to restart the entire + * service, so let's inform systemd about this + * with the special exit code 133. The service + * file uses RestartForceExitStatus=133 so + * that this results in a full nspawn + * restart. This is necessary since we might + * have cgroup parameters set we want to have + * flushed out. */ + r = 133; + break; + } } finish: