Merge sys_clone()/sys_unshare() nsproxy and namespace handling

sys_clone() and sys_unshare() both makes copies of nsproxy and its associated
namespaces.  But they have different code paths.

This patch merges all the nsproxy and its associated namespace copy/clone
handling (as much as possible).  Posted on container list earlier for
feedback.

- Create a new nsproxy and its associated namespaces and pass it back to
  caller to attach it to right process.

- Changed all copy_*_ns() routines to return a new copy of namespace
  instead of attaching it to task->nsproxy.

- Moved the CAP_SYS_ADMIN checks out of copy_*_ns() routines.

- Removed unnessary !ns checks from copy_*_ns() and added BUG_ON()
  just incase.

- Get rid of all individual unshare_*_ns() routines and make use of
  copy_*_ns() instead.

[akpm@osdl.org: cleanups, warning fix]
[clg@fr.ibm.com: remove dup_namespaces() declaration]
[serue@us.ibm.com: fix CONFIG_IPC_NS=n, clone(CLONE_NEWIPC) retval]
[akpm@linux-foundation.org: fix build with CONFIG_SYSVIPC=n]
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <containers@lists.osdl.org>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 15 deletions

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index e10267d402c..f8d3b326e93 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -49,9 +49,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
 }
 
 #ifdef CONFIG_UTS_NS
-extern int unshare_utsname(unsigned long unshare_flags,
-				struct uts_namespace **new_uts);
-extern int copy_utsname(int flags, struct task_struct *tsk);
+extern struct uts_namespace *copy_utsname(int flags, struct uts_namespace *ns);
 extern void free_uts_ns(struct kref *kref);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
@@ -59,21 +57,12 @@ static inline void put_uts_ns(struct uts_namespace *ns)
 	kref_put(&ns->kref, free_uts_ns);
 }
 #else
-static inline int unshare_utsname(unsigned long unshare_flags,
-			struct uts_namespace **new_uts)
+static inline struct uts_namespace *copy_utsname(int flags,
+						struct uts_namespace *ns)
 {
-	if (unshare_flags & CLONE_NEWUTS)
-		return -EINVAL;
-
-	return 0;
+	return ns;
 }
 
-static inline int copy_utsname(int flags, struct task_struct *tsk)
-{
-	if (flags & CLONE_NEWUTS)
-		return -EINVAL;
-	return 0;
-}
 static inline void put_uts_ns(struct uts_namespace *ns)
 {
 }