diff options
| -rw-r--r-- | Makefile.am | 4 | ||||
| -rw-r--r-- | src/core/main.c | 4 | ||||
| -rw-r--r-- | src/core/shutdown.c | 90 | ||||
| -rw-r--r-- | src/shared/switch-root.c (renamed from src/core/switch-root.c) | 35 | ||||
| -rw-r--r-- | src/shared/switch-root.h (renamed from src/core/switch-root.h) | 2 |
5 files changed, 39 insertions, 96 deletions
diff --git a/Makefile.am b/Makefile.am index e091febc1f..1facb8da43 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 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/shared/switch-root.c index 0ea61dbb29..5f075e6003 100644 --- a/src/core/switch-root.c +++ b/src/shared/switch-root.c @@ -34,7 +34,7 @@ #include "base-filesystem.h" #include "missing.h" -int switch_root(const char *new_root) { +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[] = @@ -52,14 +52,8 @@ int switch_root(const char *new_root) { 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); + temporary_old_root = strappenda(new_root, oldroot); + mkdir_p_label(temporary_old_root, 0755); old_root_remove = in_initrd(); @@ -84,7 +78,7 @@ int switch_root(const char *new_root) { snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i); char_array_0(new_mount); - mkdir_p(new_mount, 0755); + mkdir_p_label(new_mount, 0755); if ((stat(new_mount, &sb) < 0) || sb.st_dev != new_root_stat.st_dev) { @@ -97,11 +91,16 @@ int switch_root(const char *new_root) { 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 (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); - if (umount2(i, MNT_FORCE) < 0) - log_warning("Failed to unmount %s: %m", i); } } @@ -127,10 +126,10 @@ int switch_root(const char *new_root) { * 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"); + /* 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; } diff --git a/src/core/switch-root.h b/src/shared/switch-root.h index ab493b5fb1..adf893a922 100644 --- a/src/core/switch-root.h +++ b/src/shared/switch-root.h @@ -21,4 +21,4 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ -int switch_root(const char *switch_root); +int switch_root(const char *new_root, const char *oldroot, bool detach_oldroot, unsigned long mountflags); |