use the switch_root function in shutdown

removes code duplication

also move switch-root to shared

4 files changed, 19 insertions, 263 deletions

diff --git a/src/core/main.c b/src/core/main.c
index 95ab40fffc..64c2b3f3a1 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1853,8 +1853,8 @@ finish:
                          * deserializing. */
                         broadcast_signal(SIGTERM, false, true);
 
-                        /* And switch root */
-                        r = switch_root(switch_root_dir);
+                        /* And switch root with MS_MOVE, because we remove the old directory afterwards and detach it. */
+                        r = switch_root(switch_root_dir, "/mnt", true, MS_MOVE);
                         if (r < 0)
                                 log_error("Failed to switch root, ignoring: %s", strerror(-r));
                 }
diff --git a/src/core/shutdown.c b/src/core/shutdown.c
index 0e2ea5754f..1e88b05790 100644
--- a/src/core/shutdown.c
+++ b/src/core/shutdown.c
@@ -48,6 +48,7 @@
 #include "killall.h"
 #include "cgroup-util.h"
 #include "def.h"
+#include "switch-root.h"
 
 #define FINALIZE_ATTEMPTS 50
 
@@ -131,16 +132,7 @@ static int parse_argv(int argc, char *argv[]) {
         return 0;
 }
 
-static int prepare_new_root(void) {
-        static const char dirs[] =
-                "/run/initramfs/oldroot\0"
-                "/run/initramfs/proc\0"
-                "/run/initramfs/sys\0"
-                "/run/initramfs/dev\0"
-                "/run/initramfs/run\0";
-
-        const char *dir;
-
+static int switch_root_initramfs(void) {
         if (mount("/run/initramfs", "/run/initramfs", NULL, MS_BIND, NULL) < 0) {
                 log_error("Failed to mount bind /run/initramfs on /run/initramfs: %m");
                 return -errno;
@@ -151,66 +143,13 @@ static int prepare_new_root(void) {
                 return -errno;
         }
 
-        NULSTR_FOREACH(dir, dirs)
-                if (mkdir_p_label(dir, 0755) < 0 && errno != EEXIST) {
-                        log_error("Failed to mkdir %s: %m", dir);
-                        return -errno;
-                }
-
-        if (mount("/sys", "/run/initramfs/sys", NULL, MS_BIND, NULL) < 0) {
-                log_error("Failed to mount bind /sys on /run/initramfs/sys: %m");
-                return -errno;
-        }
-
-        if (mount("/proc", "/run/initramfs/proc", NULL, MS_BIND, NULL) < 0) {
-                log_error("Failed to mount bind /proc on /run/initramfs/proc: %m");
-                return -errno;
-        }
-
-        if (mount("/dev", "/run/initramfs/dev", NULL, MS_BIND, NULL) < 0) {
-                log_error("Failed to mount bind /dev on /run/initramfs/dev: %m");
-                return -errno;
-        }
-
-        if (mount("/run", "/run/initramfs/run", NULL, MS_BIND, NULL) < 0) {
-                log_error("Failed to mount bind /run on /run/initramfs/run: %m");
-                return -errno;
-        }
-
-        return 0;
+        /* switch_root with MS_BIND, because there might still be processes lurking around, which have open file desriptors.
+         * /run/initramfs/shutdown will take care of these.
+         * Also do not detach the old root, because /run/initramfs/shutdown needs to access it.
+         */
+        return switch_root("/run/initramfs", "/oldroot", false, MS_BIND);
 }
 
-static int pivot_to_new_root(void) {
-
-        if (chdir("/run/initramfs") < 0) {
-                log_error("Failed to change directory to /run/initramfs: %m");
-                return -errno;
-        }
-
-        /* Work-around for a kernel bug: for some reason the kernel
-         * refuses switching root if any file systems are mounted
-         * MS_SHARED. Hence remount them MS_PRIVATE here as a
-         * work-around.
-         *
-         * https://bugzilla.redhat.com/show_bug.cgi?id=847418 */
-        if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
-                log_warning("Failed to make \"/\" private mount: %m");
-
-        if (pivot_root(".", "oldroot") < 0) {
-                log_error("pivot failed: %m");
-                /* only chroot if pivot root succeeded */
-                return -errno;
-        }
-
-        chroot(".");
-
-        setsid();
-        make_console_stdio();
-
-        log_info("Successfully changed into root pivot.");
-
-        return 0;
-}
 
 int main(int argc, char *argv[]) {
         bool need_umount, need_swapoff, need_loop_detach, need_dm_detach;
@@ -372,16 +311,21 @@ int main(int argc, char *argv[]) {
 
         if (!in_container && !in_initrd() &&
             access("/run/initramfs/shutdown", X_OK) == 0) {
-
-                if (prepare_new_root() >= 0 &&
-                    pivot_to_new_root() >= 0) {
+                r = switch_root_initramfs();
+                if (r >= 0) {
                         arguments[0] = (char*) "/shutdown";
 
-                        log_info("Returning to initrd...");
+                        setsid();
+                        make_console_stdio();
+
+                        log_info("Successfully changed into root pivot.\n"
+                                 "Returning to initrd...");
 
                         execv("/shutdown", arguments);
                         log_error("Failed to execute shutdown binary: %m");
-                }
+                } else
+                        log_error("Failed to switch root to \"/run/initramfs\": %s", strerror(-r));
+
         }
 
         if (need_umount || need_swapoff || need_loop_detach || need_dm_detach)
diff --git a/src/core/switch-root.c b/src/core/switch-root.c
deleted file mode 100644
index 0ea61dbb29..0000000000
--- a/src/core/switch-root.c
+++ /dev/null
@@ -1,164 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-/***
-  This file is part of systemd.
-
-  Copyright 2012 Harald Hoyer, 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 <sys/stat.h>
-#include <stdbool.h>
-#include <errno.h>
-#include <string.h>
-#include <sys/mount.h>
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "util.h"
-#include "path-util.h"
-#include "switch-root.h"
-#include "mkdir.h"
-#include "base-filesystem.h"
-#include "missing.h"
-
-int switch_root(const char *new_root) {
-
-        /*  Don't try to unmount/move the old "/", there's no way to do it. */
-        static const char move_mounts[] =
-                "/dev\0"
-                "/proc\0"
-                "/sys\0"
-                "/run\0";
-
-        _cleanup_close_ int old_root_fd = -1;
-        struct stat new_root_stat;
-        bool old_root_remove;
-        const char *i, *temporary_old_root;
-        int r;
-
-        if (path_equal(new_root, "/"))
-                return 0;
-
-        /* When using pivot_root() we assume that /mnt exists as place
-         * we can temporarily move the old root to. As we immediately
-         * unmount it from there it doesn't matter much which
-         * directory we choose for this, but it should be more likely
-         * than not that /mnt exists and is suitable as mount point
-         * and is on the same fs as the old root dir */
-        temporary_old_root = strappenda(new_root, "/mnt");
-        mkdir_p(temporary_old_root, 0755);
-
-        old_root_remove = in_initrd();
-
-        if (stat(new_root, &new_root_stat) < 0) {
-                log_error("Failed to stat directory %s: %m", new_root);
-                return -errno;
-        }
-
-        /* Work-around for a kernel bug: for some reason the kernel
-         * refuses switching root if any file systems are mounted
-         * MS_SHARED. Hence remount them MS_PRIVATE here as a
-         * work-around.
-         *
-         * https://bugzilla.redhat.com/show_bug.cgi?id=847418 */
-        if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
-                log_warning("Failed to make \"/\" private mount: %m");
-
-        NULSTR_FOREACH(i, move_mounts) {
-                char new_mount[PATH_MAX];
-                struct stat sb;
-
-                snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
-                char_array_0(new_mount);
-
-                mkdir_p(new_mount, 0755);
-
-                if ((stat(new_mount, &sb) < 0) ||
-                    sb.st_dev != new_root_stat.st_dev) {
-
-                        /* Mount point seems to be mounted already or
-                         * stat failed. Unmount the old mount
-                         * point. */
-                        if (umount2(i, MNT_DETACH) < 0)
-                                log_warning("Failed to unmount %s: %m", i);
-                        continue;
-                }
-
-                if (mount(i, new_mount, NULL, MS_MOVE, NULL) < 0) {
-                        log_error("Failed to move mount %s to %s, forcing unmount: %m", i, new_mount);
-
-                        if (umount2(i, MNT_FORCE) < 0)
-                                log_warning("Failed to unmount %s: %m", i);
-                }
-        }
-
-        r = base_filesystem_create(new_root);
-        if (r < 0) {
-                log_error("Failed to create the base filesystem: %s", strerror(-r));
-                return r;
-        }
-
-        if (chdir(new_root) < 0) {
-                log_error("Failed to change directory to %s: %m", new_root);
-                return -errno;
-        }
-
-        if (old_root_remove) {
-                old_root_fd = open("/", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
-                if (old_root_fd < 0)
-                        log_warning("Failed to open root directory: %m");
-        }
-
-        /* We first try a pivot_root() so that we can umount the old
-         * root dir. In many cases (i.e. where rootfs is /), that's
-         * not possible however, and hence we simply overmount root */
-        if (pivot_root(new_root, temporary_old_root) >= 0) {
-
-                /* Immediately get rid of the old root. Since we are
-                 * running off it we need to do this lazily. */
-                if (umount2("/mnt", MNT_DETACH) < 0) {
-                        log_error("Failed to umount old root dir /mnt: %m");
-                        return -errno;
-                }
-
-        } else if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
-                log_error("Failed to mount moving %s to /: %m", new_root);
-                return -errno;
-        }
-
-        if (chroot(".") < 0) {
-                log_error("Failed to change root: %m");
-                return -errno;
-        }
-
-        if (chdir("/") < 0) {
-                log_error("Failed to change directory: %m");
-                return -errno;
-        }
-
-        if (old_root_fd >= 0) {
-                struct stat rb;
-
-                if (fstat(old_root_fd, &rb) < 0)
-                        log_warning("Failed to stat old root directory, leaving: %m");
-                else {
-                        rm_rf_children(old_root_fd, false, false, &rb);
-                        old_root_fd = -1;
-                }
-        }
-
-        return 0;
-}
diff --git a/src/core/switch-root.h b/src/core/switch-root.h
deleted file mode 100644
index ab493b5fb1..0000000000
--- a/src/core/switch-root.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
-#pragma once
-
-/***
-  This file is part of systemd.
-
-  Copyright 2012 Harald Hoyer, 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/>.
-***/
-
-int switch_root(const char *switch_root);