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-rw-r--r--kernel/exit.c7
-rw-r--r--kernel/fork.c11
-rw-r--r--kernel/nsproxy.c40
3 files changed, 36 insertions, 22 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index d22aefa..db97641 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -400,9 +400,10 @@ void daemonize(const char *name, ...)
current->fs = fs;
atomic_inc(&fs->count);
- exit_task_namespaces(current);
- current->nsproxy = init_task.nsproxy;
- get_task_namespaces(current);
+ if (current->nsproxy != init_task.nsproxy) {
+ get_nsproxy(init_task.nsproxy);
+ switch_task_namespaces(current, init_task.nsproxy);
+ }
exit_files(current);
current->files = init_task.files;
diff --git a/kernel/fork.c b/kernel/fork.c
index 2deaf48..d2f4a42 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1632,7 +1632,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
struct files_struct *fd, *new_fd = NULL;
struct sem_undo_list *new_ulist = NULL;
- struct nsproxy *new_nsproxy = NULL, *old_nsproxy = NULL;
+ struct nsproxy *new_nsproxy = NULL;
check_unshare_flags(&unshare_flags);
@@ -1662,14 +1662,13 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
if (new_fs || new_mm || new_fd || new_ulist || new_nsproxy) {
- task_lock(current);
-
if (new_nsproxy) {
- old_nsproxy = current->nsproxy;
- current->nsproxy = new_nsproxy;
- new_nsproxy = old_nsproxy;
+ switch_task_namespaces(current, new_nsproxy);
+ new_nsproxy = NULL;
}
+ task_lock(current);
+
if (new_fs) {
fs = current->fs;
current->fs = new_fs;
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index e981c61..c8ef7c2 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -26,19 +26,6 @@ static struct kmem_cache *nsproxy_cachep;
struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
-static inline void get_nsproxy(struct nsproxy *ns)
-{
- atomic_inc(&ns->count);
-}
-
-void get_task_namespaces(struct task_struct *tsk)
-{
- struct nsproxy *ns = tsk->nsproxy;
- if (ns) {
- get_nsproxy(ns);
- }
-}
-
/*
* creates a copy of "orig" with refcount 1.
*/
@@ -216,6 +203,33 @@ out:
return err;
}
+void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
+{
+ struct nsproxy *ns;
+
+ might_sleep();
+
+ ns = p->nsproxy;
+
+ rcu_assign_pointer(p->nsproxy, new);
+
+ if (ns && atomic_dec_and_test(&ns->count)) {
+ /*
+ * wait for others to get what they want from this nsproxy.
+ *
+ * cannot release this nsproxy via the call_rcu() since
+ * put_mnt_ns() will want to sleep
+ */
+ synchronize_rcu();
+ free_nsproxy(ns);
+ }
+}
+
+void exit_task_namespaces(struct task_struct *p)
+{
+ switch_task_namespaces(p, NULL);
+}
+
static int __init nsproxy_cache_init(void)
{
nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
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