[systemd-commits] Makefile.am src/core src/shared
Harald Hoyer
harald at kemper.freedesktop.org
Thu Aug 28 06:25:27 PDT 2014
Makefile.am | 4 -
src/core/main.c | 4 -
src/core/shutdown.c | 90 ++++---------------------
src/core/switch-root.c | 164 -----------------------------------------------
src/core/switch-root.h | 24 ------
src/shared/switch-root.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++
src/shared/switch-root.h | 24 ++++++
7 files changed, 208 insertions(+), 265 deletions(-)
New commits:
commit 5a4bf02ff57e4dd3453f2b868c72fe45f60033a3
Author: Harald Hoyer <harald at redhat.com>
Date: Thu Aug 21 16:21:26 2014 +0200
use the switch_root function in shutdown
removes code duplication
also move switch-root to shared
diff --git a/Makefile.am b/Makefile.am
index e091feb..1facb8d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -868,6 +868,8 @@ libsystemd_shared_la_SOURCES = \
src/shared/memfd.h \
src/shared/uid-range.c \
src/shared/uid-range.h \
+ src/shared/switch-root.h \
+ src/shared/switch-root.c \
src/shared/nss-util.h
nodist_libsystemd_shared_la_SOURCES = \
@@ -1109,8 +1111,6 @@ libsystemd_core_la_SOURCES = \
src/core/namespace.h \
src/core/build.h \
src/core/sysfs-show.h \
- src/core/switch-root.h \
- src/core/switch-root.c \
src/core/killall.h \
src/core/killall.c \
src/core/audit-fd.c \
diff --git a/src/core/main.c b/src/core/main.c
index 95ab40f..64c2b3f 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 0e2ea57..1e88b05 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 0ea61db..0000000
--- 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 ab493b5..0000000
--- 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);
diff --git a/src/shared/switch-root.c b/src/shared/switch-root.c
new file mode 100644
index 0000000..5f075e6
--- /dev/null
+++ b/src/shared/switch-root.c
@@ -0,0 +1,163 @@
+/*-*- 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, const char *oldroot, bool detach_oldroot, unsigned long mountflags) {
+
+ /* 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;
+
+ temporary_old_root = strappenda(new_root, oldroot);
+ mkdir_p_label(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_label(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, mountflags, NULL) < 0) {
+ if (mountflags & MS_MOVE) {
+ 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);
+ }
+ if (mountflags & MS_BIND)
+ log_error("Failed to bind mount %s to %s: %m", i, new_mount);
+
+ }
+ }
+
+ 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, if detach_oldroot is set.
+ * Since we are running off it we need to do this lazily. */
+ if (detach_oldroot && umount2(oldroot, MNT_DETACH) < 0) {
+ log_error("Failed to umount old root dir %s: %m", oldroot);
+ 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/shared/switch-root.h b/src/shared/switch-root.h
new file mode 100644
index 0000000..adf893a
--- /dev/null
+++ b/src/shared/switch-root.h
@@ -0,0 +1,24 @@
+/*-*- 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 *new_root, const char *oldroot, bool detach_oldroot, unsigned long mountflags);
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