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>

5 files changed, 16 insertions, 24 deletions

diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 6da6772c19ff..1980867a64a4 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -92,16 +92,19 @@ extern struct ipc_namespace init_ipc_ns;
 
 #ifdef CONFIG_SYSVIPC
 #define INIT_IPC_NS(ns)         .ns             = &init_ipc_ns,
-extern int copy_ipcs(unsigned long flags, struct task_struct *tsk);
+extern struct ipc_namespace *copy_ipcs(unsigned long flags,
+                                                struct ipc_namespace *ns);
 #else
 #define INIT_IPC_NS(ns)
-static inline int copy_ipcs(unsigned long flags, struct task_struct *tsk)
-{ return 0; }
+static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
+                                                struct ipc_namespace *ns)
+{
+        return ns;
+}
 #endif
 
 #ifdef CONFIG_IPC_NS
 extern void free_ipc_ns(struct kref *kref);
-extern int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns);
 #endif
 
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
diff --git a/include/linux/mnt_namespace.h b/include/linux/mnt_namespace.h
index 4af0b1fc282a..1fa4d9813b31 100644
--- a/include/linux/mnt_namespace.h
+++ b/include/linux/mnt_namespace.h
@@ -14,10 +14,9 @@ struct mnt_namespace {
         int event;
 };
 
-extern int copy_mnt_ns(int, struct task_struct *);
-extern void __put_mnt_ns(struct mnt_namespace *ns);
-extern struct mnt_namespace *dup_mnt_ns(struct task_struct *,
+extern struct mnt_namespace *copy_mnt_ns(int, struct mnt_namespace *,
                 struct fs_struct *);
+extern void __put_mnt_ns(struct mnt_namespace *ns);
 
 static inline void put_mnt_ns(struct mnt_namespace *ns)
 {
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 0b9f0dc30d61..189e0dc993ab 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -31,10 +31,11 @@ struct nsproxy {
 };
 extern struct nsproxy init_nsproxy;
 
-struct nsproxy *dup_namespaces(struct nsproxy *orig);
 int copy_namespaces(int flags, struct task_struct *tsk);
 void get_task_namespaces(struct task_struct *tsk);
 void free_nsproxy(struct nsproxy *ns);
+int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
+        struct fs_struct *);
 
 static inline void put_nsproxy(struct nsproxy *ns)
 {
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 2833806d42c6..169c6c24209b 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -29,7 +29,7 @@ static inline void get_pid_ns(struct pid_namespace *ns)
         kref_get(&ns->kref);
 }
 
-extern int copy_pid_ns(int flags, struct task_struct *tsk);
+extern struct pid_namespace *copy_pid_ns(int flags, struct pid_namespace *ns);
 extern void free_pid_ns(struct kref *kref);
 
 static inline void put_pid_ns(struct pid_namespace *ns)
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index e10267d402c5..f8d3b326e93a 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)
 {
 }