diff options
Diffstat (limited to 'src/machine-id-setup.c')
| -rw-r--r-- | src/machine-id-setup.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/src/machine-id-setup.c b/src/machine-id-setup.c new file mode 100644 index 0000000000..940670b339 --- /dev/null +++ b/src/machine-id-setup.c @@ -0,0 +1,166 @@ +/*-*- 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 General Public License as published by + the Free Software Foundation; either version 2 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 + General Public License for more details. + + You should have received a copy of the GNU 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 "machine-id-setup.h" +#include "macro.h" +#include "util.h" +#include "log.h" + +static int generate(char id[34]) { + int fd; + char buf[16]; + char *p, *q; + ssize_t k; + + assert(id); + + /* First, try reading the D-Bus machine id, unless it is a symlink */ + if ((fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW)) >= 0) { + + k = loop_read(fd, id, 33, 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, generate a random machine id */ + if ((fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) { + log_error("Failed to open /dev/urandom: %m"); + return -errno; + } + + k = loop_read(fd, buf, sizeof(buf), false); + close_nointr_nofail(fd); + + if (k != sizeof(buf)) { + log_error("Failed to read /dev/urandom: %s", strerror(k < 0 ? -k : EIO)); + return k < 0 ? (int) k : -EIO; + } + + for (p = buf, q = id; p < buf + 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); + + if ((fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0644)) >= 0) + writable = true; + else { + if ((fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 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 */ + + if ((r = generate(id)) < 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 + * /dev/.systemd/machine-id as a replacement */ + + mkdir_p("/dev/.systemd", 0755); + + if ((r = write_one_line_file("/dev/.systemd/machine-id", id)) < 0) { + log_error("Cannot write /dev/.systemd/machine-id: %s", strerror(-r)); + + unlink("/dev/.systemd/machine-id"); + goto finish; + } + + /* And now, let's mount it over */ + r = mount("/dev/.systemd/machine-id", "/etc/machine-id", "bind", MS_BIND|MS_RDONLY, NULL) < 0 ? -errno : 0; + unlink("/dev/.systemd/machine-id"); + + if (r < 0) + log_error("Failed to mount /etc/machine-id: %s", strerror(-r)); + else + log_info("Installed non-transient /etc/machine-id file."); + +finish: + + if (fd >= 0) + close_nointr_nofail(fd); + + return r; +} |