diff options
Diffstat (limited to 'src/core/machine-id-setup.c')
| -rw-r--r-- | src/core/machine-id-setup.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c new file mode 100644 index 0000000000..7f4c23b130 --- /dev/null +++ b/src/core/machine-id-setup.c @@ -0,0 +1,246 @@ +/*-*- 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" + +static int shorten_uuid(char destination[36], const char *source) { + 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]) { + int fd, r; + unsigned char *p; + sd_id128_t buf; + char *q; + ssize_t k; + const char *vm_id; + + assert(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); + if (fd >= 0) { + + 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 */ + + 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 (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 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; + } + } + + 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; + } + + 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(void) { + int fd, r; + bool writable; + struct stat st; + char id[34]; /* 32 + \n + \0 */ + mode_t m; + + m = 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. */ + + 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; + } + + writable = false; + } + + umask(m); + + if (fstat(fd, &st) < 0) { + log_error("fstat() failed: %m"); + r = -errno; + goto finish; + } + + if (S_ISREG(st.st_mode)) { + if (loop_read(fd, id, 32, false) >= 32) { + r = 0; + goto finish; + } + } + + /* Hmm, so, the id currently stored is not useful, then let's + * generate one */ + + r = generate(id); + if (r < 0) + goto finish; + + if (S_ISREG(st.st_mode) && writable) { + lseek(fd, 0, SEEK_SET); + + if (loop_write(fd, id, 33, false) == 33) { + r = 0; + goto finish; + } + } + + close_nointr_nofail(fd); + fd = -1; + + /* 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); + + if (r < 0) { + log_error("Cannot write /run/machine-id: %s", strerror(-r)); + + unlink("/run/machine-id"); + goto finish; + } + + /* And now, let's mount it over */ + r = mount("/run/machine-id", "/etc/machine-id", NULL, MS_BIND, 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."); + + /* Mark the mount read-only */ + mount(NULL, "/etc/machine-id", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL); + } + +finish: + + if (fd >= 0) + close_nointr_nofail(fd); + + return r; +} |