[systemd-devel] [PATCH] Do not serialize environment, when switching root

[harald at redhat.com]

From: Harald Hoyer <harald at redhat.com>

When switching root, i.e. LANG can be set to the locale of the initramfs
or "C", if it was unset. When systemd deserializes LANG in the real root
this would overwrite the setting previously gathered by locale_set().

To reproduce, boot with an initramfs without locale.conf or change
/etc/locale.conf to a different language than the initramfs and check a
daemon started by systemd:

$ tr "$\000" '\n' </proc/$(pidof sshd)/environ | grep LANG
LANG=C

To prevent that, serialization of environment variables is skipped, when
serializing for switching root.

https://bugzilla.redhat.com/show_bug.cgi?id=949525
---
 src/core/main.c    |  8 ++++----
 src/core/manager.c | 21 +++++++++++----------
 src/core/manager.h |  2 +-
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/src/core/main.c b/src/core/main.c
index 921476a..7899761 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1088,7 +1088,7 @@ static int version(void) {
         return 0;
 }
 
-static int prepare_reexecute(Manager *m, FILE **_f, FDSet **_fds, bool serialize_jobs) {
+static int prepare_reexecute(Manager *m, FILE **_f, FDSet **_fds, bool switching_root) {
         FILE *f = NULL;
         FDSet *fds = NULL;
         int r;
@@ -1113,7 +1113,7 @@ static int prepare_reexecute(Manager *m, FILE **_f, FDSet **_fds, bool serialize
                 goto fail;
         }
 
-        r = manager_serialize(m, f, fds, serialize_jobs);
+        r = manager_serialize(m, f, fds, switching_root);
         if (r < 0) {
                 log_error("Failed to serialize state: %s", strerror(-r));
                 goto fail;
@@ -1780,7 +1780,7 @@ int main(int argc, char *argv[]) {
 
                 case MANAGER_REEXECUTE:
 
-                        if (prepare_reexecute(m, &serialization, &fds, true) < 0)
+                        if (prepare_reexecute(m, &serialization, &fds, false) < 0)
                                 goto finish;
 
                         reexecute = true;
@@ -1794,7 +1794,7 @@ int main(int argc, char *argv[]) {
                         m->switch_root = m->switch_root_init = NULL;
 
                         if (!switch_root_init)
-                                if (prepare_reexecute(m, &serialization, &fds, false) < 0)
+                                if (prepare_reexecute(m, &serialization, &fds, true) < 0)
                                         goto finish;
 
                         reexecute = true;
diff --git a/src/core/manager.c b/src/core/manager.c
index 549153e..cb6f961 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -2004,7 +2004,7 @@ int manager_open_serialization(Manager *m, FILE **_f) {
         return 0;
 }
 
-int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool serialize_jobs) {
+int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool switching_root) {
         Iterator i;
         Unit *u;
         const char *t;
@@ -2032,16 +2032,17 @@ int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool serialize_jobs) {
                 dual_timestamp_serialize(f, "finish-timestamp", &m->finish_timestamp);
         }
 
-        STRV_FOREACH(e, m->environment) {
-                _cleanup_free_ char *ce;
+        if (!switching_root) {
+                STRV_FOREACH(e, m->environment) {
+                        _cleanup_free_ char *ce;
 
-                ce = cescape(*e);
-                if (ce)
-                        fprintf(f, "env=%s\n", *e);
+                        ce = cescape(*e);
+                        if (ce)
+                                fprintf(f, "env=%s\n", *e);
+                }
+                fputc('\n', f);
         }
 
-        fputc('\n', f);
-
         HASHMAP_FOREACH_KEY(u, t, m->units, i) {
                 if (u->id != t)
                         continue;
@@ -2053,7 +2054,7 @@ int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool serialize_jobs) {
                 fputs(u->id, f);
                 fputc('\n', f);
 
-                if ((r = unit_serialize(u, f, fds, serialize_jobs)) < 0) {
+                if ((r = unit_serialize(u, f, fds, !switching_root)) < 0) {
                         m->n_reloading --;
                         return r;
                 }
@@ -2241,7 +2242,7 @@ int manager_reload(Manager *m) {
                 goto finish;
         }
 
-        r = manager_serialize(m, f, fds, true);
+        r = manager_serialize(m, f, fds, false);
         if (r < 0) {
                 m->n_reloading --;
                 goto finish;
diff --git a/src/core/manager.h b/src/core/manager.h
index 9d8d943..649a8aa 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -278,7 +278,7 @@ void manager_dispatch_bus_query_pid_done(Manager *m, const char *name, pid_t pid
 
 int manager_open_serialization(Manager *m, FILE **_f);
 
-int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool serialize_jobs);
+int manager_serialize(Manager *m, FILE *f, FDSet *fds, bool switching_root);
 int manager_deserialize(Manager *m, FILE *f, FDSet *fds);
 int manager_distribute_fds(Manager *m, FDSet *fds);
 
-- 
1.8.2