/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <unistd.h> #include <stdio.h> #include <errno.h> #include <string.h> #include <stdlib.h> #include <fcntl.h> #include <sys/mount.h> #include <systemd/sd-id128.h> #include "machine-id-setup.h" #include "macro.h" #include "util.h" #include "mkdir.h" #include "log.h" #include "virt.h" #include "fileio.h" #include "path-util.h" static int shorten_uuid(char destination[34], const char source[36]) { unsigned i, j; for (i = 0, j = 0; i < 36 && j < 32; i++) { int t; t = unhexchar(source[i]); if (t < 0) continue; destination[j++] = hexchar(t); } if (i == 36 && j == 32) { destination[32] = '\n'; destination[33] = 0; return 0; } return -EINVAL; } static int generate(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; assert(id); if (asprintf(&dbus_machine_id, "%s/var/lib/dbus/machine-id", root) < 0) return log_oom(); /* 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); 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 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 (r > 0) { if (strlen(e) >= 36) { 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 */ 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; } for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) { q[0] = hexchar(*p >> 4); q[1] = hexchar(*p & 15); } id[32] = '\n'; id[33] = 0; log_info("Initializing machine ID from random generator."); return 0; } 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; char id[34]; /* 32 + \n + \0 */ int r; if (isempty(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); run_machine_id = strappenda(root, "/run/machine-id"); path_kill_slashes((char*) run_machine_id); } 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. */ 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 { fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); if (fd < 0) { log_error("Cannot open %s: %m", etc_machine_id); return -errno; } writable = false; } } 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; } /* Hmm, so, the id currently stored is not useful, then let's * generate one */ r = generate(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) return 0; } 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); } if (r < 0) { log_error("Cannot write %s: %s", run_machine_id, strerror(-r)); 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); if (r < 0) { log_error("Failed to mount %s: %m", etc_machine_id); unlink_noerrno(run_machine_id); return -errno; } 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); return 0; }