core: reuse the same /tmp, /var/tmp and inaccessible dir

All Execs within the service, will get mounted the same
/tmp and /var/tmp directories, if service is configured with
PrivateTmp=yes. Temporary directories are cleaned up by service
itself in addition to systemd-tmpfiles. Directory which is mounted
as inaccessible is created at runtime in /run/systemd.

11 files changed, 244 insertions, 151 deletions

diff --git a/src/core/execute.c b/src/core/execute.c
index 92cf174641..18e25fa6e6 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -173,6 +173,18 @@ static bool is_terminal_output(ExecOutput o) {
                 o == EXEC_OUTPUT_JOURNAL_AND_CONSOLE;
 }
 
+void exec_context_serialize(const ExecContext *context, Unit *u, FILE *f) {
+        assert(context);
+        assert(u);
+        assert(f);
+
+        if (context->tmp_dir)
+                unit_serialize_item(u, f, "tmp-dir", context->tmp_dir);
+
+        if (context->var_tmp_dir)
+                unit_serialize_item(u, f, "var-tmp-dir", context->var_tmp_dir);
+}
+
 static int open_null_as(int flags, int nfd) {
         int fd, r;
 
@@ -968,7 +980,7 @@ static int apply_seccomp(uint32_t *syscall_filter) {
 
 int exec_spawn(ExecCommand *command,
                char **argv,
-               const ExecContext *context,
+               ExecContext *context,
                int fds[], unsigned n_fds,
                char **environment,
                bool apply_permissions,
@@ -1036,6 +1048,12 @@ int exec_spawn(ExecCommand *command,
 
         cgroup_attribute_apply_list(cgroup_attributes, cgroup_bondings);
 
+        if (context->private_tmp && !context->tmp_dir && !context->var_tmp_dir) {
+                r = setup_tmpdirs(&context->tmp_dir, &context->var_tmp_dir);
+                if (r < 0)
+                        return r;
+        }
+
         pid = fork();
         if (pid < 0)
                 return -errno;
@@ -1302,6 +1320,8 @@ int exec_spawn(ExecCommand *command,
                         err = setup_namespace(context->read_write_dirs,
                                               context->read_only_dirs,
                                               context->inaccessible_dirs,
+                                              context->tmp_dir,
+                                              context->var_tmp_dir,
                                               context->private_tmp,
                                               context->mount_flags);
                         if (err < 0) {
@@ -1530,7 +1550,23 @@ void exec_context_init(ExecContext *c) {
         c->timer_slack_nsec = (nsec_t) -1;
 }
 
-void exec_context_done(ExecContext *c) {
+void exec_context_tmp_dirs_done(ExecContext *c) {
+        assert(c);
+
+        if (c->tmp_dir) {
+                rm_rf_dangerous(c->tmp_dir, false, true, false);
+                free(c->tmp_dir);
+                c->tmp_dir = NULL;
+        }
+
+        if (c->var_tmp_dir) {
+                rm_rf_dangerous(c->var_tmp_dir, false, true, false);
+                free(c->var_tmp_dir);
+                c->var_tmp_dir = NULL;
+        }
+}
+
+void exec_context_done(ExecContext *c, bool reloading_or_reexecuting) {
         unsigned l;
 
         assert(c);
@@ -1594,6 +1630,9 @@ void exec_context_done(ExecContext *c) {
 
         free(c->syscall_filter);
         c->syscall_filter = NULL;
+
+        if (!reloading_or_reexecuting)
+                exec_context_tmp_dirs_done(c);
 }
 
 void exec_command_done(ExecCommand *c) {
diff --git a/src/core/execute.h b/src/core/execute.h
index 001eb0e7cc..3ce9221ab1 100644
--- a/src/core/execute.h
+++ b/src/core/execute.h
@@ -36,6 +36,8 @@ typedef struct ExecContext ExecContext;
 struct CGroupBonding;
 struct CGroupAttribute;
 
+typedef struct Unit Unit;
+
 #include "list.h"
 #include "util.h"
 
@@ -141,6 +143,8 @@ struct ExecContext {
         bool non_blocking;
         bool private_tmp;
         bool private_network;
+        char *tmp_dir;
+        char *var_tmp_dir;
 
         bool no_new_privileges;
 
@@ -164,7 +168,7 @@ struct ExecContext {
 
 int exec_spawn(ExecCommand *command,
                char **argv,
-               const ExecContext *context,
+               ExecContext *context,
                int fds[], unsigned n_fds,
                char **environment,
                bool apply_permissions,
@@ -192,13 +196,15 @@ void exec_command_append_list(ExecCommand **l, ExecCommand *e);
 int exec_command_set(ExecCommand *c, const char *path, ...);
 
 void exec_context_init(ExecContext *c);
-void exec_context_done(ExecContext *c);
+void exec_context_done(ExecContext *c, bool reloading_or_reexecuting);
+void exec_context_tmp_dirs_done(ExecContext *c);
 void exec_context_dump(ExecContext *c, FILE* f, const char *prefix);
 void exec_context_tty_reset(const ExecContext *context);
 
 int exec_context_load_environment(const ExecContext *c, char ***l);
 
 bool exec_context_may_touch_console(ExecContext *c);
+void exec_context_serialize(const ExecContext *c, Unit *u, FILE *f);
 
 void exec_status_start(ExecStatus *s, pid_t pid);
 void exec_status_exit(ExecStatus *s, ExecContext *context, pid_t pid, int code, int status);
diff --git a/src/core/manager.c b/src/core/manager.c
index 8e66732cd7..a01710f445 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -2333,6 +2333,12 @@ static bool manager_is_booting_or_shutting_down(Manager *m) {
         return false;
 }
 
+bool manager_is_reloading_or_reexecuting(Manager *m) {
+        assert(m);
+
+        return m->n_reloading != 0;
+}
+
 void manager_reset_failed(Manager *m) {
         Unit *u;
         Iterator i;
diff --git a/src/core/manager.h b/src/core/manager.h
index c486a16887..9d8d9439d2 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -85,6 +85,7 @@ struct Watch {
 #include "set.h"
 #include "dbus.h"
 #include "path-lookup.h"
+#include "execute.h"
 
 struct Manager {
         /* Note that the set of units we know of is allowed to be
@@ -283,6 +284,8 @@ int manager_distribute_fds(Manager *m, FDSet *fds);
 
 int manager_reload(Manager *m);
 
+bool manager_is_reloading_or_reexecuting(Manager *m);
+
 void manager_reset_failed(Manager *m);
 
 void manager_send_unit_audit(Manager *m, Unit *u, int type, bool success);
diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
index ce10be944a..6140f56d83 100644
--- a/src/core/mount-setup.c
+++ b/src/core/mount-setup.c
@@ -447,6 +447,7 @@ int mount_setup(bool loaded_policy) {
          * systemd. */
         mkdir_label("/run/systemd", 0755);
         mkdir_label("/run/systemd/system", 0755);
+        mkdir_label("/run/systemd/inaccessible", 0000);
 
         return 0;
 }
diff --git a/src/core/mount.c b/src/core/mount.c
index 7a1b411c7b..0adf04e9bf 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -25,6 +25,7 @@
 #include <sys/epoll.h>
 #include <signal.h>
 
+#include "manager.h"
 #include "unit.h"
 #include "mount.h"
 #include "load-fragment.h"
@@ -126,7 +127,7 @@ static void mount_done(Unit *u) {
         mount_parameters_done(&m->parameters_proc_self_mountinfo);
         mount_parameters_done(&m->parameters_fragment);
 
-        exec_context_done(&m->exec_context);
+        exec_context_done(&m->exec_context, manager_is_reloading_or_reexecuting(u->manager));
         exec_command_done_array(m->exec_command, _MOUNT_EXEC_COMMAND_MAX);
         m->control_command = NULL;
 
@@ -870,6 +871,7 @@ static void mount_enter_dead(Mount *m, MountResult f) {
         if (f != MOUNT_SUCCESS)
                 m->result = f;
 
+        exec_context_tmp_dirs_done(&m->exec_context);
         mount_set_state(m, m->result != MOUNT_SUCCESS ? MOUNT_FAILED : MOUNT_DEAD);
 }
 
@@ -1163,6 +1165,8 @@ static int mount_serialize(Unit *u, FILE *f, FDSet *fds) {
         if (m->control_command_id >= 0)
                 unit_serialize_item(u, f, "control-command", mount_exec_command_to_string(m->control_command_id));
 
+        exec_context_serialize(&m->exec_context, UNIT(m), f);
+
         return 0;
 }
 
@@ -1219,7 +1223,22 @@ static int mount_deserialize_item(Unit *u, const char *key, const char *value, F
                         m->control_command_id = id;
                         m->control_command = m->exec_command + id;
                 }
+        } else if (streq(key, "tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
+
+                m->exec_context.tmp_dir = t;
+        } else if (streq(key, "var-tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
 
+                m->exec_context.var_tmp_dir = t;
         } else
                 log_debug_unit(UNIT(m)->id,
                                "Unknown serialization key '%s'", key);
diff --git a/src/core/namespace.c b/src/core/namespace.c
index ba18ddc5b0..ceeed2e1ae 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -36,23 +36,24 @@
 #include "path-util.h"
 #include "namespace.h"
 #include "missing.h"
+#include "execute.h"
 
-typedef enum PathMode {
+typedef enum MountMode {
         /* This is ordered by priority! */
         INACCESSIBLE,
         READONLY,
         PRIVATE_TMP,
         PRIVATE_VAR_TMP,
         READWRITE
-} PathMode;
+} MountMode;
 
-typedef struct Path {
+typedef struct BindMount {
         const char *path;
-        PathMode mode;
+        MountMode mode;
         bool done;
-} Path;
+} BindMount;
 
-static int append_paths(Path **p, char **strv, PathMode mode) {
+static int append_mounts(BindMount **p, char **strv, MountMode mode) {
         char **i;
 
         STRV_FOREACH(i, strv) {
@@ -68,8 +69,8 @@ static int append_paths(Path **p, char **strv, PathMode mode) {
         return 0;
 }
 
-static int path_compare(const void *a, const void *b) {
-        const Path *p = a, *q = b;
+static int mount_path_compare(const void *a, const void *b) {
+        const BindMount *p = a, *q = b;
 
         if (path_equal(p->path, q->path)) {
 
@@ -93,14 +94,13 @@ static int path_compare(const void *a, const void *b) {
         return 0;
 }
 
-static void drop_duplicates(Path *p, unsigned *n, bool *need_inaccessible) {
-        Path *f, *t, *previous;
+static void drop_duplicates(BindMount *m, unsigned *n) {
+        BindMount *f, *t, *previous;
 
-        assert(p);
+        assert(m);
         assert(n);
-        assert(need_inaccessible);
 
-        for (f = p, t = p, previous = NULL; f < p+*n; f++) {
+        for (f = m, t = m, previous = NULL; f < m+*n; f++) {
 
                 /* The first one wins */
                 if (previous && path_equal(f->path, previous->path))
@@ -109,37 +109,33 @@ static void drop_duplicates(Path *p, unsigned *n, bool *need_inaccessible) {
                 t->path = f->path;
                 t->mode = f->mode;
 
-                if (t->mode == INACCESSIBLE)
-                        *need_inaccessible = true;
-
                 previous = t;
 
                 t++;
         }
 
-        *n = t - p;
+        *n = t - m;
 }
 
 static int apply_mount(
-                Path *p,
+                BindMount *m,
                 const char *tmp_dir,
-                const char *var_tmp_dir,
-                const char *inaccessible_dir) {
+                const char *var_tmp_dir) {
 
         const char *what;
         int r;
 
-        assert(p);
+        assert(m);
 
-        switch (p->mode) {
+        switch (m->mode) {
 
         case INACCESSIBLE:
-                what = inaccessible_dir;
+                what = "/run/systemd/inaccessible";
                 break;
 
         case READONLY:
         case READWRITE:
-                what = p->path;
+                what = m->path;
                 break;
 
         case PRIVATE_TMP:
@@ -156,133 +152,99 @@ static int apply_mount(
 
         assert(what);
 
-        r = mount(what, p->path, NULL, MS_BIND|MS_REC, NULL);
+        r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL);
         if (r >= 0)
-                log_debug("Successfully mounted %s to %s", what, p->path);
+                log_debug("Successfully mounted %s to %s", what, m->path);
 
         return r;
 }
 
-static int make_read_only(Path *p) {
+static int make_read_only(BindMount *m) {
         int r;
 
-        assert(p);
+        assert(m);
 
-        if (p->mode != INACCESSIBLE && p->mode != READONLY)
+        if (m->mode != INACCESSIBLE && m->mode != READONLY)
                 return 0;
 
-        r = mount(NULL, p->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
+        r = mount(NULL, m->path, NULL, MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL);
         if (r < 0)
                 return -errno;
 
         return 0;
 }
 
-int setup_namespace(
-                char **writable,
-                char **readable,
-                char **inaccessible,
-                bool private_tmp,
-                unsigned long flags) {
-
-        char
-                tmp_dir[] = "/tmp/systemd-private-XXXXXX",
-                var_tmp_dir[] = "/var/tmp/systemd-private-XXXXXX",
-                inaccessible_dir[] = "/tmp/systemd-inaccessible-XXXXXX";
-
-        Path *paths, *p;
-        unsigned n;
-        bool need_inaccessible = false;
-        bool remove_tmp = false, remove_var_tmp = false, remove_inaccessible = false;
-        int r;
-
-        if (!flags)
-                flags = MS_SHARED;
+int setup_tmpdirs(char **tmp_dir,
+                  char **var_tmp_dir) {
+        int r = 0;
+        char tmp_dir_template[] = "/tmp/systemd-private-XXXXXX",
+             var_tmp_dir_template[] = "/var/tmp/systemd-private-XXXXXX";
 
-        n =
-                strv_length(writable) +
-                strv_length(readable) +
-                strv_length(inaccessible) +
-                (private_tmp ? 2 : 0);
+        assert(tmp_dir);
+        assert(var_tmp_dir);
 
-        p = paths = alloca(sizeof(Path) * n);
-        if ((r = append_paths(&p, writable, READWRITE)) < 0 ||
-            (r = append_paths(&p, readable, READONLY)) < 0 ||
-            (r = append_paths(&p, inaccessible, INACCESSIBLE)) < 0)
-                goto fail;
+        r = create_tmp_dir(tmp_dir_template, 0000, true, tmp_dir);
+        if (r < 0)
+                goto fail2;
 
-        if (private_tmp) {
-                p->path = "/tmp";
-                p->mode = PRIVATE_TMP;
-                p++;
+        r = create_tmp_dir(var_tmp_dir_template, 0000, true, var_tmp_dir);
+        if (r < 0)
+                goto fail1;
 
-                p->path = "/var/tmp";
-                p->mode = PRIVATE_VAR_TMP;
-                p++;
-        }
+        return 0;
 
-        assert(paths + n == p);
+fail1:
+        rmdir(*tmp_dir);
+        free(*tmp_dir);
+        *tmp_dir = NULL;
 
-        qsort(paths, n, sizeof(Path), path_compare);
-        drop_duplicates(paths, &n, &need_inaccessible);
+fail2:
+        return r;
+}
 
-        if (need_inaccessible) {
-                mode_t u;
-                char *d;
+int setup_namespace(char** read_write_dirs,
+                    char** read_only_dirs,
+                    char** inaccessible_dirs,
+                    char* tmp_dir,
+                    char* var_tmp_dir,
+                    bool private_tmp,
+                    unsigned mount_flags) {
 
-                u = umask(0777);
-                d = mkdtemp(inaccessible_dir);
-                umask(u);
+        unsigned n = strv_length(read_write_dirs) +
+                     strv_length(read_only_dirs) +
+                     strv_length(inaccessible_dirs) +
+                     (private_tmp ? 2 : 0);
+        BindMount *m, *mounts;
+        int r = 0;
 
-                if (!d) {
-                        r = -errno;
-                        goto fail;
-                }
+        if (!mount_flags)
+                mount_flags = MS_SHARED;
 
-                remove_inaccessible = true;
+        if (unshare(CLONE_NEWNS) < 0) {
+                r = -errno;
+                goto fail;
         }
 
-        if (private_tmp) {
-                mode_t u;
-                char *d;
-
-                u = umask(0000);
-                d = mkdtemp(tmp_dir);
-                umask(u);
-
-                if (!d) {
-                        r = -errno;
-                        goto fail;
-                }
-
-                remove_tmp = true;
-
-                u = umask(0000);
-                d = mkdtemp(var_tmp_dir);
-                umask(u);
-
-                if (!d) {
-                        r = -errno;
-                        goto fail;
-                }
-
-                remove_var_tmp = true;
+        m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
+        if ((r = append_mounts(&m, read_write_dirs, READWRITE)) < 0 ||
+                (r = append_mounts(&m, read_only_dirs, READONLY)) < 0 ||
+                (r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE)) < 0)
+                goto fail;
 
-                if (chmod(tmp_dir, 0777 + S_ISVTX) < 0) {
-                        r = -errno;
-                        goto fail;
-                }
+        if (private_tmp) {
+                m->path = "/tmp";
+                m->mode = PRIVATE_TMP;
+                m++;
 
-                if (chmod(var_tmp_dir, 0777 + S_ISVTX) < 0) {
-                        r = -errno;
-                        goto fail;
-                }
+                m->path = "/var/tmp";
+                m->mode = PRIVATE_VAR_TMP;
+                m++;
         }
 
-        if (unshare(CLONE_NEWNS) < 0) {
-                r = -errno;
-                goto fail;
-        }
+        assert(mounts + n == m);
+
+        qsort(mounts, n, sizeof(BindMount), mount_path_compare);
+        drop_duplicates(mounts, &n);
 
         /* Remount / as SLAVE so that nothing now mounted in the namespace
            shows up in the parent */
@@ -291,20 +253,20 @@ int setup_namespace(
                 goto fail;
         }
 
-        for (p = paths; p < paths + n; p++) {
-                r = apply_mount(p, tmp_dir, var_tmp_dir, inaccessible_dir);
+        for (m = mounts; m < mounts + n; ++m) {
+                r = apply_mount(m, tmp_dir, var_tmp_dir);
                 if (r < 0)
                         goto undo_mounts;
         }
 
-        for (p = paths; p < paths + n; p++) {
-                r = make_read_only(p);
+        for (m = mounts; m < mounts + n; ++m) {
+                r = make_read_only(m);
                 if (r < 0)
                         goto undo_mounts;
         }
 
         /* Remount / as the desired mode */
-        if (mount(NULL, "/", NULL, flags|MS_REC, NULL) < 0) {
+        if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
                 r = -errno;
                 goto undo_mounts;
         }
@@ -312,19 +274,11 @@ int setup_namespace(
         return 0;
 
 undo_mounts:
-        for (p = paths; p < paths + n; p++)
-                if (p->done)
-                        umount2(p->path, MNT_DETACH);
+        for (m = mounts; m < mounts + n; ++m) {
+                if (m->done)
+                        umount2(m->path, MNT_DETACH);
+        }
 
 fail:
-        if (remove_inaccessible)
-                rmdir(inaccessible_dir);
-
-        if (remove_tmp)
-                rmdir(tmp_dir);
-
-        if (remove_var_tmp)
-                rmdir(var_tmp_dir);
-
         return r;
 }
diff --git a/src/core/namespace.h b/src/core/namespace.h
index 5d72ed91fb..7b886b8abf 100644
--- a/src/core/namespace.h
+++ b/src/core/namespace.h
@@ -23,9 +23,13 @@
 
 #include <stdbool.h>
 
-int setup_namespace(
-                char **writable,
-                char **readable,
-                char **inaccessible,
-                bool private_tmp,
-                unsigned long flags);
+typedef struct ExecContext ExecContext;
+
+int setup_tmpdirs(char **tmp_dir, char **var_tmp_dir);
+int setup_namespace(char **read_write_dirs,
+                    char **read_only_dirs,
+                    char **inaccessible_dirs,
+                    char *tmp_dir,
+                    char *var_tmp_dir,
+                    bool private_tmp,
+                    unsigned mount_flags);
diff --git a/src/core/service.c b/src/core/service.c
index fd90ceba05..080d583b69 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -283,7 +283,7 @@ static void service_done(Unit *u) {
         free(s->status_text);
         s->status_text = NULL;
 
-        exec_context_done(&s->exec_context);
+        exec_context_done(&s->exec_context, manager_is_reloading_or_reexecuting(u->manager));
         exec_command_free_array(s->exec_command, _SERVICE_EXEC_COMMAND_MAX);
         s->control_command = NULL;
         s->main_command = NULL;
@@ -1932,6 +1932,9 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart)
 
         s->forbid_restart = false;
 
+        /* we want fresh tmpdirs in case service is started again immediately */
+        exec_context_tmp_dirs_done(&s->exec_context);
+
         return;
 
 fail:
@@ -2638,6 +2641,12 @@ static int service_serialize(Unit *u, FILE *f, FDSet *fds) {
                 dual_timestamp_serialize(f, "watchdog-timestamp",
                                          &s->watchdog_timestamp);
 
+        if (s->exec_context.tmp_dir)
+                unit_serialize_item(u, f, "tmp-dir", s->exec_context.tmp_dir);
+
+        if (s->exec_context.var_tmp_dir)
+                unit_serialize_item(u, f, "var-tmp-dir", s->exec_context.var_tmp_dir);
+
         return 0;
 }
 
@@ -2756,7 +2765,23 @@ static int service_deserialize_item(Unit *u, const char *key, const char *value,
                 dual_timestamp_deserialize(value, &s->main_exec_status.exit_timestamp);
         else if (streq(key, "watchdog-timestamp"))
                 dual_timestamp_deserialize(value, &s->watchdog_timestamp);
-        else
+        else if (streq(key, "tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
+
+                s->exec_context.tmp_dir = t;
+        } else if (streq(key, "var-tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
+
+                s->exec_context.var_tmp_dir = t;
+        } else
                 log_debug_unit(u->id, "Unknown serialization key '%s'", key);
 
         return 0;
diff --git a/src/core/socket.c b/src/core/socket.c
index ee9de4e14c..a3e3631dac 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -127,7 +127,7 @@ static void socket_done(Unit *u) {
 
         socket_free_ports(s);
 
-        exec_context_done(&s->exec_context);
+        exec_context_done(&s->exec_context, manager_is_reloading_or_reexecuting(u->manager));
         exec_command_free_array(s->exec_command, _SOCKET_EXEC_COMMAND_MAX);
         s->control_command = NULL;
 
@@ -1253,6 +1253,7 @@ static void socket_enter_dead(Socket *s, SocketResult f) {
         if (f != SOCKET_SUCCESS)
                 s->result = f;
 
+        exec_context_tmp_dirs_done(&s->exec_context);
         socket_set_state(s, s->result != SOCKET_SUCCESS ? SOCKET_FAILED : SOCKET_DEAD);
 }
 
@@ -1742,6 +1743,8 @@ static int socket_serialize(Unit *u, FILE *f, FDSet *fds) {
                 }
         }
 
+        exec_context_serialize(&s->exec_context, UNIT(s), f);
+
         return 0;
 }
 
@@ -1901,7 +1904,22 @@ static int socket_deserialize_item(Unit *u, const char *key, const char *value,
                                 p->fd = fdset_remove(fds, fd);
                         }
                 }
+        } else if (streq(key, "tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
+
+                s->exec_context.tmp_dir = t;
+        } else if (streq(key, "var-tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
 
+                s->exec_context.var_tmp_dir = t;
         } else
                 log_debug_unit(UNIT(s)->id,
                                "Unknown serialization key '%s'", key);
diff --git a/src/core/swap.c b/src/core/swap.c
index a0e55a0c03..dc98f47387 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -125,7 +125,7 @@ static void swap_done(Unit *u) {
         free(s->parameters_fragment.what);
         s->parameters_fragment.what = NULL;
 
-        exec_context_done(&s->exec_context);
+        exec_context_done(&s->exec_context, manager_is_reloading_or_reexecuting(u->manager));
         exec_command_done_array(s->exec_command, _SWAP_EXEC_COMMAND_MAX);
         s->control_command = NULL;
 
@@ -632,6 +632,7 @@ static void swap_enter_dead(Swap *s, SwapResult f) {
         if (f != SWAP_SUCCESS)
                 s->result = f;
 
+        exec_context_tmp_dirs_done(&s->exec_context);
         swap_set_state(s, s->result != SWAP_SUCCESS ? SWAP_FAILED : SWAP_DEAD);
 }
 
@@ -831,6 +832,8 @@ static int swap_serialize(Unit *u, FILE *f, FDSet *fds) {
         if (s->control_command_id >= 0)
                 unit_serialize_item(u, f, "control-command", swap_exec_command_to_string(s->control_command_id));
 
+        exec_context_serialize(&s->exec_context, UNIT(s), f);
+
         return 0;
 }
 
@@ -874,7 +877,22 @@ static int swap_deserialize_item(Unit *u, const char *key, const char *value, FD
                         s->control_command_id = id;
                         s->control_command = s->exec_command + id;
                 }
+        } else if (streq(key, "tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
+
+                s->exec_context.tmp_dir = t;
+        } else if (streq(key, "var-tmp-dir")) {
+                char *t;
+
+                t = strdup(value);
+                if (!t)
+                        return log_oom();
 
+                s->exec_context.var_tmp_dir = t;
         } else
                 log_debug_unit(u->id, "Unknown serialization key '%s'", key);