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=7505dcbcaa1b97c31c7bab74903b83b523a6a917;hp=f154800484f823fe1628b7a27826b3ab937ffb5c;hb=c6ac7e4b98828b3b9ea5bd510cf8cc3c25dc2e58;hpb=3577de7ac39c54821e1d1d946db65e109dfb94b2 diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c index f15480048..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" @@ -41,6 +40,12 @@ 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; @@ -51,85 +56,115 @@ static int shorten_uuid(char destination[34], const char source[36]) { 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); - return -EINVAL; + if (lseek(fd, 0, SEEK_SET) < 0) + return -errno; + + return loop_write(fd, id, 33, false); } -static int generate(char id[34], const char *root) { +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; - _cleanup_free_ char *dbus_machine_id = NULL; + char *q; + const char *vm_id, *dbus_machine_id; assert(id); - if (asprintf(&dbus_machine_id, "%s/var/lib/dbus/machine-id", root) < 0) - return log_oom(); + 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(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); if (fd >= 0) { - k = loop_read(fd, id, 33, false); + r = read_machine_id(fd, id); safe_close(fd); - if (k == 33 && id[32] == '\n') { - - id[32] = 0; - if (id128_is_valid(id)) { - id[32] = '\n'; - id[33] = 0; - - log_info("Initializing machine ID from D-Bus machine ID."); - return 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 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; - - 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) { + _cleanup_free_ char *e = NULL; + + 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 container UUID."); 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 */ + } 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]; + 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) { - k = loop_read(fd, uuid, 36, false); - safe_close(fd); + 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 (k >= 36) { - r = shorten_uuid(id, uuid); if (r >= 0) { - log_info("Initializing machine ID from KVM UUID."); - return 0; + r = shorten_uuid(id, uuid); + if (r >= 0) { + log_info("Initializing machine ID from KVM UUID."); + return 0; + } } } } @@ -138,10 +173,8 @@ static int generate(char id[34], const char *root) { /* 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); @@ -159,8 +192,7 @@ static int generate(char id[34], const char *root) { int machine_id_setup(const char *root) { const char *etc_machine_id, *run_machine_id; _cleanup_close_ int fd = -1; - bool writable = false; - struct stat st; + bool writable = true; char id[34]; /* 32 + \n + \0 */ int r; @@ -168,11 +200,13 @@ int machine_id_setup(const char *root) { etc_machine_id = "/etc/machine-id"; run_machine_id = "/run/machine-id"; } else { - etc_machine_id = strappenda(root, "/etc/machine-id"); - path_kill_slashes((char*) etc_machine_id); + char *x; - run_machine_id = strappenda(root, "/run/machine-id"); - path_kill_slashes((char*) run_machine_id); + x = strjoina(root, "/etc/machine-id"); + etc_machine_id = path_kill_slashes(x); + + x = strjoina(root, "/run/machine-id"); + run_machine_id = path_kill_slashes(x); } RUN_WITH_UMASK(0000) { @@ -183,12 +217,21 @@ int machine_id_setup(const char *root) { mkdir_parents(etc_machine_id, 0755); fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); - if (fd >= 0) - writable = true; - else { + 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 %s: %m", etc_machine_id); + 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; } @@ -196,32 +239,19 @@ int machine_id_setup(const char *root) { } } - if (fstat(fd, &st) < 0) { - log_error("fstat() failed: %m"); - return -errno; - } - - if (S_ISREG(st.st_mode)) - if (loop_read(fd, id, 33, false) == 33 && id[32] == '\n') { - id[32] = 0; - - if (id128_is_valid(id)) - return 0; - } + 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, root); + r = generate_machine_id(id, root); if (r < 0) return r; - if (S_ISREG(st.st_mode) && writable) { - lseek(fd, 0, SEEK_SET); - - if (loop_write(fd, id, 33, false) == 33) + if (writable) + if (write_machine_id(fd, id) >= 0) return 0; - } fd = safe_close(fd); @@ -232,24 +262,100 @@ int machine_id_setup(const char *root) { r = write_string_file(run_machine_id, id); } if (r < 0) { - log_error("Cannot write %s: %s", run_machine_id, strerror(-r)); - unlink(run_machine_id); - return r; + (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, NULL, MS_BIND, NULL); - if (r < 0) { - log_error("Failed to mount %s: %m", etc_machine_id); - unlink_noerrno(run_machine_id); - return -errno; + 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("Failed to make transient %s read-only: %m", etc_machine_id); + 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; + + 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); + + /* 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; }