X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fcore%2Fmachine-id-setup.c;h=7505dcbcaa1b97c31c7bab74903b83b523a6a917;hb=f5b51ea7fcb0b6380c3ceb4d4f3f22f647c6fd32;hp=636519c00c81d7d17b41fc675642fd114bbac3f5;hpb=ab94af9201496ea3aa59bbf2a01eb750fbd1c08a;p=elogind.git diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c index 636519c00..7505dcbca 100644 --- a/src/core/machine-id-setup.c +++ b/src/core/machine-id-setup.c @@ -23,11 +23,10 @@ #include #include #include -#include #include #include -#include +#include "systemd/sd-id128.h" #include "machine-id-setup.h" #include "macro.h" @@ -35,10 +34,18 @@ #include "mkdir.h" #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; + assert(destination); + assert(source); + + /* Converts a UUID into a machine ID, by lowercasing it and + * removing dashes. Validates everything. */ + for (i = 0, j = 0; i < 36 && j < 32; i++) { int t; @@ -49,92 +56,125 @@ static int shorten_uuid(char destination[36], const char *source) { destination[j++] = hexchar(t); } - if (i == 36 && j == 32) { - destination[32] = '\n'; - destination[33] = 0; - return 0; - } + if (i != 36 || j != 32) + return -EINVAL; + + destination[32] = '\n'; + destination[33] = 0; + return 0; +} + +static int read_machine_id(int fd, char id[34]) { + char id_to_validate[34]; + int r; + + assert(fd >= 0); + assert(id); + + /* Reads a machine ID from a file, validates it, and returns + * it. The returned ID ends in a newline. */ + + r = loop_read_exact(fd, id_to_validate, 33, false); + if (r < 0) + return r; + + if (id_to_validate[32] != '\n') + return -EINVAL; + + id_to_validate[32] = 0; + + if (!id128_is_valid(id_to_validate)) + return -EINVAL; + + memcpy(id, id_to_validate, 32); + id[32] = '\n'; + id[33] = 0; + return 0; +} + +static int write_machine_id(int fd, char id[34]) { + assert(fd >= 0); + assert(id); + + if (lseek(fd, 0, SEEK_SET) < 0) + return -errno; - return -EINVAL; + return loop_write(fd, id, 33, false); } -static int generate(char id[34]) { +static int generate_machine_id(char id[34], const char *root) { int fd, r; unsigned char *p; sd_id128_t buf; - char *q; - ssize_t k; - const char *vm_id; + char *q; + const char *vm_id, *dbus_machine_id; assert(id); + if (isempty(root)) + dbus_machine_id = "/var/lib/dbus/machine-id"; + else + dbus_machine_id = strjoina(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) { + r = read_machine_id(fd, id); + safe_close(fd); - k = loop_read(fd, id, 32, false); - close_nointr_nofail(fd); - - if (k >= 32) { - id[32] = '\n'; - id[33] = 0; - + if (r >= 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 */ - - 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); - close_nointr_nofail(fd); + 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) { + _cleanup_free_ char *e = NULL; - if (k >= 36) { - r = shorten_uuid(id, uuid); + r = getenv_for_pid(1, "container_uuid", &e); + if (r > 0) { + r = shorten_uuid(id, e); if (r >= 0) { - log_info("Initializing machine ID from KVM UUID"); + log_info("Initializing machine ID from container UUID."); 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 (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; + } 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[36]; + + fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); + if (fd >= 0) { + r = loop_read_exact(fd, uuid, 36, false); + safe_close(fd); + + if (r >= 0) { + r = shorten_uuid(id, uuid); + if (r >= 0) { + log_info("Initializing machine ID from KVM UUID."); + return 0; + } + } } } - - free(e); } } /* 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); @@ -149,94 +189,173 @@ static int generate(char id[34]) { return 0; } -int machine_id_setup(void) { - int fd, r; - bool writable; - struct stat st; +int machine_id_setup(const char *root) { + const char *etc_machine_id, *run_machine_id; + _cleanup_close_ int fd = -1; + bool writable = true; char id[34]; /* 32 + \n + \0 */ - mode_t m; - - m = umask(0000); + int r; - /* We create this 0444, to indicate that this isn't really - * something you should ever modify. Of course, since the file - * will be owned by root it doesn't matter much, but maybe - * people look. */ + if (isempty(root)) { + etc_machine_id = "/etc/machine-id"; + run_machine_id = "/run/machine-id"; + } else { + char *x; - 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); - if (fd < 0) { - umask(m); - log_error("Cannot open /etc/machine-id: %m"); - return -errno; - } + x = strjoina(root, "/etc/machine-id"); + etc_machine_id = path_kill_slashes(x); - writable = false; + x = strjoina(root, "/run/machine-id"); + run_machine_id = path_kill_slashes(x); } - umask(m); + RUN_WITH_UMASK(0000) { + /* We create this 0444, to indicate that this isn't really + * something you should ever modify. Of course, since the file + * will be owned by root it doesn't matter much, but maybe + * people look. */ - if (fstat(fd, &st) < 0) { - log_error("fstat() failed: %m"); - r = -errno; - goto finish; - } + 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) { + if (old_errno == EROFS && errno == ENOENT) + log_error_errno(errno, + "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; + } - if (S_ISREG(st.st_mode)) { - if (loop_read(fd, id, 32, false) >= 32) { - r = 0; - goto finish; + writable = false; } } + if (read_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_machine_id(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 (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 */ - m = umask(0022); - r = write_one_line_file("/run/machine-id", id); - umask(m); - + RUN_WITH_UMASK(0022) { + 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; + (void) unlink(run_machine_id); + return log_error_errno(r, "Cannot write %s: %m", run_machine_id); } /* And now, let's mount it over */ - r = mount("/run/machine-id", "/etc/machine-id", "bind", MS_BIND|MS_RDONLY, NULL) < 0 ? -errno : 0; - 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."); + if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) { + (void) unlink_noerrno(run_machine_id); + return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); + } + + log_info("Installed transient %s file.", etc_machine_id); + + /* 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 0; +} + +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; -finish: + x = strjoina(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 = read_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); - if (fd >= 0) - close_nointr_nofail(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 r; + return 0; }