049af8ad0c
The idea is that anything which is related to actually manipulating mounts is in mount-util.c, but functions for mountpoint introspection are moved to the new file. Anything which requires libmount must be in mount-util.c. This was supposed to be a preparation for further changes, with no functional difference, but it results in a significant change in linkage: $ ldd build/libnss_*.so.2 (before) build/libnss_myhostname.so.2: linux-vdso.so.1 (0x00007fff77bf5000) librt.so.1 => /lib64/librt.so.1 (0x00007f4bbb7b2000) libmount.so.1 => /lib64/libmount.so.1 (0x00007f4bbb755000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f4bbb734000) libc.so.6 => /lib64/libc.so.6 (0x00007f4bbb56e000) /lib64/ld-linux-x86-64.so.2 (0x00007f4bbb8c1000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007f4bbb51b000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007f4bbb512000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f4bbb4e3000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007f4bbb45e000) libdl.so.2 => /lib64/libdl.so.2 (0x00007f4bbb458000) build/libnss_mymachines.so.2: linux-vdso.so.1 (0x00007ffc19cc0000) librt.so.1 => /lib64/librt.so.1 (0x00007fdecb74b000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fdecb744000) libmount.so.1 => /lib64/libmount.so.1 (0x00007fdecb6e7000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fdecb6c6000) libc.so.6 => /lib64/libc.so.6 (0x00007fdecb500000) /lib64/ld-linux-x86-64.so.2 (0x00007fdecb8a9000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007fdecb4ad000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007fdecb4a2000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fdecb475000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007fdecb3f0000) libdl.so.2 => /lib64/libdl.so.2 (0x00007fdecb3ea000) build/libnss_resolve.so.2: linux-vdso.so.1 (0x00007ffe8ef8e000) librt.so.1 => /lib64/librt.so.1 (0x00007fcf314bd000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fcf314b6000) libmount.so.1 => /lib64/libmount.so.1 (0x00007fcf31459000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fcf31438000) libc.so.6 => /lib64/libc.so.6 (0x00007fcf31272000) /lib64/ld-linux-x86-64.so.2 (0x00007fcf31615000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007fcf3121f000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007fcf31214000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fcf311e7000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007fcf31162000) libdl.so.2 => /lib64/libdl.so.2 (0x00007fcf3115c000) build/libnss_systemd.so.2: linux-vdso.so.1 (0x00007ffda6d17000) librt.so.1 => /lib64/librt.so.1 (0x00007f610b83c000) libcap.so.2 => /lib64/libcap.so.2 (0x00007f610b835000) libmount.so.1 => /lib64/libmount.so.1 (0x00007f610b7d8000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f610b7b7000) libc.so.6 => /lib64/libc.so.6 (0x00007f610b5f1000) /lib64/ld-linux-x86-64.so.2 (0x00007f610b995000) libblkid.so.1 => /lib64/libblkid.so.1 (0x00007f610b59e000) libuuid.so.1 => /lib64/libuuid.so.1 (0x00007f610b593000) libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f610b566000) libpcre2-8.so.0 => /lib64/libpcre2-8.so.0 (0x00007f610b4e1000) libdl.so.2 => /lib64/libdl.so.2 (0x00007f610b4db000) (after) build/libnss_myhostname.so.2: linux-vdso.so.1 (0x00007fff0b5e2000) librt.so.1 => /lib64/librt.so.1 (0x00007fde0c328000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fde0c307000) libc.so.6 => /lib64/libc.so.6 (0x00007fde0c141000) /lib64/ld-linux-x86-64.so.2 (0x00007fde0c435000) build/libnss_mymachines.so.2: linux-vdso.so.1 (0x00007ffdc30a7000) librt.so.1 => /lib64/librt.so.1 (0x00007f06ecabb000) libcap.so.2 => /lib64/libcap.so.2 (0x00007f06ecab4000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f06eca93000) libc.so.6 => /lib64/libc.so.6 (0x00007f06ec8cd000) /lib64/ld-linux-x86-64.so.2 (0x00007f06ecc15000) build/libnss_resolve.so.2: linux-vdso.so.1 (0x00007ffe95747000) librt.so.1 => /lib64/librt.so.1 (0x00007fa56a80f000) libcap.so.2 => /lib64/libcap.so.2 (0x00007fa56a808000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fa56a7e7000) libc.so.6 => /lib64/libc.so.6 (0x00007fa56a621000) /lib64/ld-linux-x86-64.so.2 (0x00007fa56a964000) build/libnss_systemd.so.2: linux-vdso.so.1 (0x00007ffe67b51000) librt.so.1 => /lib64/librt.so.1 (0x00007ffb32113000) libcap.so.2 => /lib64/libcap.so.2 (0x00007ffb3210c000) libpthread.so.0 => /lib64/libpthread.so.0 (0x00007ffb320eb000) libc.so.6 => /lib64/libc.so.6 (0x00007ffb31f25000) /lib64/ld-linux-x86-64.so.2 (0x00007ffb3226a000) I don't quite understand what is going on here, but let's not be too picky.
244 lines
9.7 KiB
C
244 lines
9.7 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <fcntl.h>
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#include <sched.h>
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#include <sys/mount.h>
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#include <unistd.h>
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#include "sd-id128.h"
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "fs-util.h"
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#include "id128-util.h"
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#include "log.h"
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#include "machine-id-setup.h"
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#include "macro.h"
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#include "mkdir.h"
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#include "mountpoint-util.h"
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#include "path-util.h"
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#include "process-util.h"
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#include "stat-util.h"
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#include "string-util.h"
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#include "umask-util.h"
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#include "util.h"
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#include "virt.h"
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static int generate_machine_id(const char *root, sd_id128_t *ret) {
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const char *dbus_machine_id;
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_cleanup_close_ int fd = -1;
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int r;
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assert(ret);
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/* First, try reading the D-Bus machine id, unless it is a symlink */
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dbus_machine_id = prefix_roota(root, "/var/lib/dbus/machine-id");
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fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
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if (fd >= 0) {
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if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0) {
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log_info("Initializing machine ID from D-Bus machine ID.");
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return 0;
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}
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fd = safe_close(fd);
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}
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if (isempty(root)) {
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/* If that didn't work, see if we are running in a container,
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* and a machine ID was passed in via $container_uuid the way
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* libvirt/LXC does it */
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if (detect_container() > 0) {
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_cleanup_free_ char *e = NULL;
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if (getenv_for_pid(1, "container_uuid", &e) > 0 &&
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sd_id128_from_string(e, ret) >= 0) {
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log_info("Initializing machine ID from container UUID.");
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return 0;
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}
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} else if (detect_vm() == VIRTUALIZATION_KVM) {
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/* If we are not running in a container, see if we are
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* running in qemu/kvm and a machine ID was passed in
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* via -uuid on the qemu/kvm command line */
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if (id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, ret) >= 0) {
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log_info("Initializing machine ID from KVM UUID.");
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return 0;
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}
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}
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}
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/* If that didn't work, generate a random machine id */
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r = sd_id128_randomize(ret);
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if (r < 0)
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return log_error_errno(r, "Failed to generate randomized machine ID: %m");
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log_info("Initializing machine ID from random generator.");
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return 0;
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}
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int machine_id_setup(const char *root, sd_id128_t machine_id, sd_id128_t *ret) {
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const char *etc_machine_id, *run_machine_id;
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_cleanup_close_ int fd = -1;
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bool writable;
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int r;
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etc_machine_id = prefix_roota(root, "/etc/machine-id");
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RUN_WITH_UMASK(0000) {
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/* We create this 0444, to indicate that this isn't really
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* something you should ever modify. Of course, since the file
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* will be owned by root it doesn't matter much, but maybe
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* people look. */
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(void) mkdir_parents(etc_machine_id, 0755);
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fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
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if (fd < 0) {
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int old_errno = errno;
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fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
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if (fd < 0) {
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if (old_errno == EROFS && errno == ENOENT)
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return log_error_errno(errno,
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"System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
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"Booting up is supported only when:\n"
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"1) /etc/machine-id exists and is populated.\n"
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"2) /etc/machine-id exists and is empty.\n"
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"3) /etc/machine-id is missing and /etc is writable.\n");
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else
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return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
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}
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writable = false;
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} else
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writable = true;
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}
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/* A we got a valid machine ID argument, that's what counts */
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if (sd_id128_is_null(machine_id)) {
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/* Try to read any existing machine ID */
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if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0)
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return 0;
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/* Hmm, so, the id currently stored is not useful, then let's generate one */
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r = generate_machine_id(root, &machine_id);
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if (r < 0)
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return r;
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}
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if (writable) {
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if (lseek(fd, 0, SEEK_SET) == (off_t) -1)
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return log_error_errno(errno, "Failed to seek %s: %m", etc_machine_id);
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if (ftruncate(fd, 0) < 0)
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return log_error_errno(errno, "Failed to truncate %s: %m", etc_machine_id);
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if (id128_write_fd(fd, ID128_PLAIN, machine_id, true) >= 0)
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goto finish;
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}
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fd = safe_close(fd);
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/* Hmm, we couldn't write it? So let's write it to /run/machine-id as a replacement */
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run_machine_id = prefix_roota(root, "/run/machine-id");
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RUN_WITH_UMASK(0022)
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r = id128_write(run_machine_id, ID128_PLAIN, machine_id, false);
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if (r < 0) {
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(void) unlink(run_machine_id);
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return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
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}
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/* And now, let's mount it over */
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if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {
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(void) unlink_noerrno(run_machine_id);
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return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
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}
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log_info("Installed transient %s file.", etc_machine_id);
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/* Mark the mount read-only */
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if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
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log_warning_errno(errno, "Failed to make transient %s read-only, ignoring: %m", etc_machine_id);
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finish:
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if (ret)
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*ret = machine_id;
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return 0;
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}
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int machine_id_commit(const char *root) {
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_cleanup_close_ int fd = -1, initial_mntns_fd = -1;
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const char *etc_machine_id;
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sd_id128_t id;
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int r;
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/* Replaces a tmpfs bind mount of /etc/machine-id by a proper file, atomically. For this, the umount is removed
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* in a mount namespace, a new file is created at the right place. Afterwards the mount is also removed in the
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* original mount namespace, thus revealing the file that was just created. */
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etc_machine_id = prefix_roota(root, "/etc/machine-id");
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r = path_is_mount_point(etc_machine_id, NULL, 0);
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if (r < 0)
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return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
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if (r == 0) {
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log_debug("%s is not a mount point. Nothing to do.", etc_machine_id);
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return 0;
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}
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/* Read existing machine-id */
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fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
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if (fd < 0)
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return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
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r = fd_is_temporary_fs(fd);
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if (r < 0)
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return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);
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if (r == 0)
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return log_error_errno(SYNTHETIC_ERRNO(EROFS),
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"%s is not on a temporary file system.",
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etc_machine_id);
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r = id128_read_fd(fd, ID128_PLAIN, &id);
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if (r < 0)
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return log_error_errno(r, "We didn't find a valid machine ID in %s: %m", etc_machine_id);
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fd = safe_close(fd);
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/* Store current mount namespace */
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r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL);
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if (r < 0)
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return log_error_errno(r, "Can't fetch current mount namespace: %m");
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/* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */
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if (unshare(CLONE_NEWNS) < 0)
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return log_error_errno(errno, "Failed to enter new namespace: %m");
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if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0)
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return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");
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if (umount(etc_machine_id) < 0)
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return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);
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/* Update a persistent version of etc_machine_id */
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r = id128_write(etc_machine_id, ID128_PLAIN, id, true);
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if (r < 0)
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return log_error_errno(r, "Cannot write %s. This is mandatory to get a persistent machine ID: %m", etc_machine_id);
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/* Return to initial namespace and proceed a lazy tmpfs unmount */
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r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1);
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if (r < 0)
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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);
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if (umount2(etc_machine_id, MNT_DETACH) < 0)
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return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);
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return 0;
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}
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