X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fcore%2Fmachine-id-setup.c;h=7e0aee6a75ba883b92f737033cd0f99730d1fdf6;hp=fbba3aab78d0f0073a65b34d7374cb8a8c7f24c0;hb=f131770b1465fbf423881f16ba85523a05f846fe;hpb=5c0d398dfc4d79df2209515d28cafd9dc129838e diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c index fbba3aab7..7e0aee6a7 100644 --- a/src/core/machine-id-setup.c +++ b/src/core/machine-id-setup.c @@ -27,7 +27,7 @@ #include #include -#include +#include "systemd/sd-id128.h" #include "machine-id-setup.h" #include "macro.h" @@ -36,8 +36,9 @@ #include "log.h" #include "virt.h" #include "fileio.h" +#include "path-util.h" -static int shorten_uuid(char destination[36], const char *source) { +static int shorten_uuid(char destination[34], const char source[36]) { unsigned i, j; for (i = 0, j = 0; i < 36 && j < 32; i++) { @@ -59,83 +60,89 @@ static int shorten_uuid(char destination[36], const char *source) { return -EINVAL; } -static int generate(char id[34]) { +static int generate(char id[34], const char *root) { int fd, r; unsigned char *p; sd_id128_t buf; - char *q; + char *q; ssize_t k; - const char *vm_id; + const char *vm_id, *dbus_machine_id; assert(id); + if (isempty(root)) + dbus_machine_id = "/var/lib/dbus/machine-id"; + else + dbus_machine_id = strappenda(root, "/var/lib/dbus/machine-id"); + /* First, try reading the D-Bus machine id, unless it is a symlink */ - fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); if (fd >= 0) { + k = loop_read(fd, id, 33, false); + safe_close(fd); - k = loop_read(fd, id, 32, false); - close_nointr_nofail(fd); - - if (k >= 32) { - id[32] = '\n'; - id[33] = 0; - - log_info("Initializing machine ID from D-Bus machine ID."); - return 0; - } - } - - /* If that didn't work, see if we are running in qemu/kvm and a - * machine ID was passed in via -uuid on the qemu/kvm command - * line */ + if (k == 33 && id[32] == '\n') { - r = detect_vm(&vm_id); - if (r > 0 && streq(vm_id, "kvm")) { - char uuid[37]; + id[32] = 0; + if (id128_is_valid(id)) { + id[32] = '\n'; + id[33] = 0; - fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); - if (fd >= 0) { - k = loop_read(fd, uuid, 36, false); - close_nointr_nofail(fd); - - if (k >= 36) { - r = shorten_uuid(id, uuid); - if (r >= 0) { - log_info("Initializing machine ID from KVM UUID."); - return 0; - } + log_info("Initializing machine ID from D-Bus machine ID."); + return 0; } } } - /* If that didn't work either, see if we are running in a - * container, and a machine ID was passed in via - * $container_uuid the way libvirt/LXC does it */ - r = detect_container(NULL); - if (r > 0) { - char *e; - - r = getenv_for_pid(1, "container_uuid", &e); + if (isempty(root)) { + /* If that didn't work, see if we are running in a container, + * and a machine ID was passed in via $container_uuid the way + * libvirt/LXC does it */ + r = detect_container(NULL); if (r > 0) { - if (strlen(e) >= 36) { - r = shorten_uuid(id, e); - if (r >= 0) { - log_info("Initializing machine ID from container UUID."); - free(e); - return 0; + _cleanup_free_ char *e = NULL; + + r = getenv_for_pid(1, "container_uuid", &e); + if (r > 0) { + if (strlen(e) >= 36) { + r = shorten_uuid(id, e); + if (r >= 0) { + log_info("Initializing machine ID from container UUID."); + return 0; + } } } - free(e); + } else { + /* If we are not running in a container, see if we are + * running in qemu/kvm and a machine ID was passed in + * via -uuid on the qemu/kvm command line */ + + r = detect_vm(&vm_id); + if (r > 0 && streq(vm_id, "kvm")) { + char uuid[37]; + + fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + if (fd >= 0) { + k = loop_read(fd, uuid, 36, false); + safe_close(fd); + + if (k >= 36) { + r = shorten_uuid(id, uuid); + if (r >= 0) { + log_info("Initializing machine ID from KVM UUID."); + return 0; + } + } + } + } } } /* If that didn't work, generate a random machine id */ r = sd_id128_randomize(&buf); - if (r < 0) { - log_error("Failed to open /dev/urandom: %s", strerror(-r)); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to open /dev/urandom: %m"); for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) { q[0] = hexchar(*p >> 4); @@ -150,11 +157,136 @@ static int generate(char id[34]) { return 0; } -int machine_id_setup(void) { - int fd, r; - bool writable; +static int get_valid_machine_id(int fd, char id[34]) { + char id_to_validate[34]; + + assert(fd >= 0); + assert(id); + + if (loop_read(fd, id_to_validate, 33, false) == 33 && id_to_validate[32] == '\n') { + id_to_validate[32] = 0; + + if (id128_is_valid(id_to_validate)) { + memcpy(id, id_to_validate, 32); + id[32] = '\n'; + id[33] = 0; + return 0; + } + } + + return -EINVAL; +} + +static int write_machine_id(int fd, char id[34]) { + assert(fd >= 0); + assert(id); + lseek(fd, 0, SEEK_SET); + + if (loop_write(fd, id, 33, false) == 0) + return 0; + + return -errno; +} + +int machine_id_commit(const char *root) { + _cleanup_close_ int fd = -1, initial_mntns_fd = -1; + const char *etc_machine_id; + char id[34]; /* 32 + \n + \0 */ + int r; + + if (isempty(root)) + etc_machine_id = "/etc/machine-id"; + else { + char *x; + + x = strappenda(root, "/etc/machine-id"); + etc_machine_id = path_kill_slashes(x); + } + + r = path_is_mount_point(etc_machine_id, false); + if (r < 0) + return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id); + if (r == 0) { + log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id); + return 0; + } + + /* Read existing machine-id */ + fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (fd < 0) + return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); + + r = get_valid_machine_id(fd, id); + if (r < 0) + return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id); + + r = is_fd_on_temporary_fs(fd); + if (r < 0) + return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id); + if (r == 0) { + log_error("%s is not on a temporary file system.", etc_machine_id); + return -EROFS; + } + + fd = safe_close(fd); + + /* Store current mount namespace */ + r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL); + if (r < 0) + return log_error_errno(r, "Can't fetch current mount namespace: %m"); + + /* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */ + if (unshare(CLONE_NEWNS) < 0) + return log_error_errno(errno, "Failed to enter new namespace: %m"); + + if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) + return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m"); + + if (umount(etc_machine_id) < 0) + return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id); + + /* Update a persistent version of etc_machine_id */ + fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); + if (fd < 0) + return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id); + + r = write_machine_id(fd, id); + if (r < 0) + return log_error_errno(r, "Cannot write %s: %m", etc_machine_id); + + fd = safe_close(fd); + + /* Return to initial namespace and proceed a lazy tmpfs unmount */ + r = namespace_enter(-1, initial_mntns_fd, -1, -1); + if (r < 0) + return log_warning_errno(r, "Failed to switch back to initial mount namespace: %m.\nWe'll keep transient %s file until next reboot.", etc_machine_id); + + if (umount2(etc_machine_id, MNT_DETACH) < 0) + return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id); + + return 0; +} + +int machine_id_setup(const char *root) { + const char *etc_machine_id, *run_machine_id; + _cleanup_close_ int fd = -1; + bool writable = true; struct stat st; char id[34]; /* 32 + \n + \0 */ + int r; + + if (isempty(root)) { + etc_machine_id = "/etc/machine-id"; + run_machine_id = "/run/machine-id"; + } else { + char *x; + + x = strappenda(root, "/etc/machine-id"); + etc_machine_id = path_kill_slashes(x); + + x = strappenda(root, "/run/machine-id"); + run_machine_id = path_kill_slashes(x); + } RUN_WITH_UMASK(0000) { /* We create this 0444, to indicate that this isn't really @@ -162,13 +294,21 @@ int machine_id_setup(void) { * will be owned by root it doesn't matter much, but maybe * people look. */ - fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); - if (fd >= 0) - writable = true; - else { - fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY); + mkdir_parents(etc_machine_id, 0755); + fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); + if (fd < 0) { + int old_errno = errno; + + fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); if (fd < 0) { - log_error("Cannot open /etc/machine-id: %m"); + if (old_errno == EROFS && errno == ENOENT) + log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n" + "Booting up is supported only when:\n" + "1) /etc/machine-id exists and is populated.\n" + "2) /etc/machine-id exists and is empty.\n" + "3) /etc/machine-id is missing and /etc is writable.\n"); + else + log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); return -errno; } @@ -176,69 +316,50 @@ int machine_id_setup(void) { } } - if (fstat(fd, &st) < 0) { - log_error("fstat() failed: %m"); - r = -errno; - goto finish; - } + if (fstat(fd, &st) < 0) + return log_error_errno(errno, "fstat() failed: %m"); - if (S_ISREG(st.st_mode)) { - if (loop_read(fd, id, 32, false) >= 32) { - r = 0; - goto finish; - } - } + if (S_ISREG(st.st_mode) && get_valid_machine_id(fd, id) == 0) + return 0; /* Hmm, so, the id currently stored is not useful, then let's * generate one */ - r = generate(id); + r = generate(id, root); if (r < 0) - goto finish; - - if (S_ISREG(st.st_mode) && writable) { - lseek(fd, 0, SEEK_SET); + return r; - if (loop_write(fd, id, 33, false) == 33) { - r = 0; - goto finish; - } - } + if (S_ISREG(st.st_mode) && writable) + if (write_machine_id(fd, id) == 0) + return 0; - close_nointr_nofail(fd); - fd = -1; + fd = safe_close(fd); /* Hmm, we couldn't write it? So let's write it to * /run/machine-id as a replacement */ RUN_WITH_UMASK(0022) { - r = write_string_file("/run/machine-id", id); + r = write_string_file(run_machine_id, id); } if (r < 0) { - log_error("Cannot write /run/machine-id: %s", strerror(-r)); - - unlink("/run/machine-id"); - goto finish; + log_error_errno(r, "Cannot write %s: %m", run_machine_id); + unlink(run_machine_id); + return r; } /* And now, let's mount it over */ - r = mount("/run/machine-id", "/etc/machine-id", NULL, MS_BIND, NULL) < 0 ? -errno : 0; + r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL); if (r < 0) { - unlink("/run/machine-id"); - log_error("Failed to mount /etc/machine-id: %s", strerror(-r)); - } else { - log_info("Installed transient /etc/machine-id file."); - - /* Mark the mount read-only */ - if (mount(NULL, "/etc/machine-id", NULL, - MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) - log_warning("Failed to make transient /etc/machine-id read-only"); + log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); + unlink_noerrno(run_machine_id); + return -errno; } -finish: + log_info("Installed transient %s file.", etc_machine_id); - if (fd >= 0) - close_nointr_nofail(fd); + /* Mark the mount read-only */ + if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) + log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id); - return r; + return 0; }