[CRIU] [PATCH RESEND v1 55/55] ns: Nested pid_ns support

[Kirill Tkhai]

Allow nested pid_ns, but turn restoring of pgid and sid off for the cases,
when there are child pid namespaces. This functionality will be realized
by Pavel Tikhomirov, he is working on that.

Also, current criu has a problem with restoring tun if nested net namespaces
exist. See my letter "[net_ns] Problem of restoring tun in nested net namespace".
So, I've turned tun test off for a while.

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 criu/cr-restore.c         |    5 +++++
 criu/include/namespaces.h |    2 +-
 criu/pstree.c             |    2 ++
 test/zdtm/static/tun.desc |    2 +-
 4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index bb5abd70..8bb045b3 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -1263,6 +1263,8 @@ static void restore_sid(void)
 {
 	pid_t sid;
 
+	if (!list_empty(&top_pid_ns->children))
+		return;
 	/*
 	 * SID can only be reset to pid or inherited from parent.
 	 * Thus we restore it right here to let our kids inherit
@@ -1306,6 +1308,9 @@ static void restore_pgid(void)
 
 	pid_t pgid, my_pgid = last_level_pid(current->pgid);
 
+	if (!list_empty(&top_pid_ns->children))
+		return;
+
 	pr_info("Restoring %d to %d pgid\n", vpid(current), my_pgid);
 
 	pgid = getpgrp();
diff --git a/criu/include/namespaces.h b/criu/include/namespaces.h
index d8126eb5..068d9e66 100644
--- a/criu/include/namespaces.h
+++ b/criu/include/namespaces.h
@@ -39,7 +39,7 @@
 #define CLONE_ALLNS	(CLONE_NEWPID | CLONE_NEWNET | CLONE_NEWIPC | CLONE_NEWUTS | CLONE_NEWNS | CLONE_NEWUSER | CLONE_NEWCGROUP)
 
 /* Nested namespaces are supported only for these types */
-#define CLONE_SUBNS	(CLONE_NEWNS | CLONE_NEWNET | CLONE_NEWUSER)
+#define CLONE_SUBNS	(CLONE_NEWNS | CLONE_NEWNET | CLONE_NEWUSER | CLONE_NEWPID)
 
 #define MAX_NS_NESTING	32
 #define EXTRA_SIZE	20
diff --git a/criu/pstree.c b/criu/pstree.c
index 09a7ac8c..f3492010 100644
--- a/criu/pstree.c
+++ b/criu/pstree.c
@@ -858,6 +858,8 @@ static int prepare_pstree_ids(void)
 	struct pstree_item *item, *child, *helper, *tmp;
 	LIST_HEAD(helpers);
 
+	if (!list_empty(&top_pid_ns->children))
+		return 0;
 	pid_t current_pgid = getpgid(getpid());
 
 	/*
diff --git a/test/zdtm/static/tun.desc b/test/zdtm/static/tun.desc
index 8c7cfe86..eac32c2d 100644
--- a/test/zdtm/static/tun.desc
+++ b/test/zdtm/static/tun.desc
@@ -1 +1 @@
-{'flavor': 'ns uns', 'flags': 'suid', 'feature': 'tun'}
+{'flavor': 'ns uns', 'flags': 'suid noauto', 'feature': 'tun'}