switch-root: use MS_REC for /run, unless we are soft-rebooting

[thirdparty/systemd.git] / src / shared / switch-root.c

diff --git a/src/shared/switch-root.c b/src/shared/switch-root.c
index 070d5bd908b3c24b7cc70b06176afef2e338558a..37395e02ad4cf8367dc25038bb562920d2c67817 100644 (file)
--- a/src/shared/switch-root.c
+++ b/src/shared/switch-root.c
@@ -30,17 +30,23 @@ int switch_root(const char *new_root,
                 const char *old_root_after,   /* path below the new root, where to place the old root after the transition; may be NULL to unmount it */
                 SwitchRootFlags flags) {
 
+        /* Stuff mounted below /run we don't save on soft reboot, as it might have lost its relevance, i.e.
+         * credentials, removable media and such, we rather want that the new boot mounts this fresh.
+         * But on the switch from initrd we do use MS_REC, as it is expected that mounts set up in /run
+         * are maintained. */
+        unsigned long run_mount_flags = MS_BIND|(!FLAGS_SET(flags, SWITCH_ROOT_SKIP_RECURSIVE_RUN) ? MS_REC : 0);
         struct {
                 const char *path;
                 unsigned long mount_flags;
+                bool skip_if_run_is_rec; /* For child mounts of /run, if it's moved recursively no need to handle */
         } transfer_table[] = {
-                { "/dev",                                 MS_BIND|MS_REC }, /* Recursive, because we want to save the original /dev/shm + /dev/pts and similar */
-                { "/sys",                                 MS_BIND|MS_REC }, /* Similar, we want to retain various API VFS, or the cgroupv1 /sys/fs/cgroup/ tree */
-                { "/proc",                                MS_BIND|MS_REC }, /* Similar */
-                { "/run",                                 MS_BIND        }, /* Stuff mounted below this we don't save, as it might have lost its relevance, i.e. credentials, removable media and such, we rather want that the new boot mounts this fresh */
-                { SYSTEM_CREDENTIALS_DIRECTORY,           MS_BIND        }, /* Credentials passed into the system should survive */
-                { ENCRYPTED_SYSTEM_CREDENTIALS_DIRECTORY, MS_BIND        }, /* Similar */
-                { "/run/host",                            MS_BIND|MS_REC }, /* Host supplied hierarchy should also survive */
+                { "/dev",                                 MS_BIND|MS_REC,  false }, /* Recursive, because we want to save the original /dev/shm + /dev/pts and similar */
+                { "/sys",                                 MS_BIND|MS_REC,  false }, /* Similar, we want to retain various API VFS, or the cgroupv1 /sys/fs/cgroup/ tree */
+                { "/proc",                                MS_BIND|MS_REC,  false }, /* Similar */
+                { "/run",                                 run_mount_flags, false }, /* Recursive except on soft reboot, see above */
+                { SYSTEM_CREDENTIALS_DIRECTORY,           MS_BIND,         true },  /* Credentials passed into the system should survive */
+                { ENCRYPTED_SYSTEM_CREDENTIALS_DIRECTORY, MS_BIND,         true },  /* Similar */
+                { "/run/host",                            MS_BIND|MS_REC,  true },  /* Host supplied hierarchy should also survive */
         };
 
         _cleanup_close_ int old_root_fd = -EBADF, new_root_fd = -EBADF;
@@ -112,6 +118,9 @@ int switch_root(const char *new_root,
         FOREACH_ARRAY(transfer, transfer_table, ELEMENTSOF(transfer_table)) {
                 _cleanup_free_ char *chased = NULL;
 
+                if (transfer->skip_if_run_is_rec && !FLAGS_SET(flags, SWITCH_ROOT_SKIP_RECURSIVE_RUN))
+                        continue;
+
                 if (access(transfer->path, F_OK) < 0) {
                         log_debug_errno(errno, "Path '%s' to move to target root directory, not found, ignoring: %m", transfer->path);
                         continue;