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, 10 insertions, 43 deletions

diff --git a/ipc/util.c b/ipc/util.c
index 0b652387d169..0ad5b1c3ca01 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -85,53 +85,20 @@ err_mem:
         return ERR_PTR(err);
 }
 
-int unshare_ipcs(unsigned long unshare_flags, struct ipc_namespace **new_ipc)
+struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
 {
-        struct ipc_namespace *new;
-
-        if (unshare_flags & CLONE_NEWIPC) {
-                if (!capable(CAP_SYS_ADMIN))
-                        return -EPERM;
-
-                new = clone_ipc_ns(current->nsproxy->ipc_ns);
-                if (IS_ERR(new))
-                        return PTR_ERR(new);
-
-                *new_ipc = new;
-        }
-
-        return 0;
-}
-
-int copy_ipcs(unsigned long flags, struct task_struct *tsk)
-{
-        struct ipc_namespace *old_ns = tsk->nsproxy->ipc_ns;
         struct ipc_namespace *new_ns;
-        int err = 0;
 
-        if (!old_ns)
-                return 0;
-
-        get_ipc_ns(old_ns);
+        BUG_ON(!ns);
+        get_ipc_ns(ns);
 
         if (!(flags & CLONE_NEWIPC))
-                return 0;
+                return ns;
 
-        if (!capable(CAP_SYS_ADMIN)) {
-                err = -EPERM;
-                goto out;
-        }
+        new_ns = clone_ipc_ns(ns);
 
-        new_ns = clone_ipc_ns(old_ns);
-        if (!new_ns) {
-                err = -ENOMEM;
-                goto out;
-        }
-
-        tsk->nsproxy->ipc_ns = new_ns;
-out:
-        put_ipc_ns(old_ns);
-        return err;
+        put_ipc_ns(ns);
+        return new_ns;
 }
 
 void free_ipc_ns(struct kref *kref)
@@ -145,11 +112,11 @@ void free_ipc_ns(struct kref *kref)
         kfree(ns);
 }
 #else
-int copy_ipcs(unsigned long flags, struct task_struct *tsk)
+struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
 {
         if (flags & CLONE_NEWIPC)
-                return -EINVAL;
-        return 0;
+                return ERR_PTR(-EINVAL);
+        return ns;
 }
 #endif