sched: fix mysql+oltp regression

[safe/jmp/linux-2.6] / kernel / user_namespace.c

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 3d79642..a9ab059 100644 (file)
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -8,18 +8,47 @@
 #include <linux/module.h>
 #include <linux/version.h>
 #include <linux/nsproxy.h>
+#include <linux/slab.h>
 #include <linux/user_namespace.h>
 
-struct user_namespace init_user_ns = {
-       .kref = {
-               .refcount       = ATOMIC_INIT(2),
-       },
-       .root_user = &root_user,
-};
+/*
+ * Clone a new ns copying an original user ns, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return NULL on error (failure to kmalloc), new ns otherwise
+ */
+static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
+{
+       struct user_namespace *ns;
+       struct user_struct *new_user;
+       int n;
+
+       ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
+       if (!ns)
+               return ERR_PTR(-ENOMEM);
+
+       kref_init(&ns->kref);
 
-EXPORT_SYMBOL_GPL(init_user_ns);
+       for (n = 0; n < UIDHASH_SZ; ++n)
+               INIT_HLIST_HEAD(ns->uidhash_table + n);
 
-#ifdef CONFIG_USER_NS
+       /* Insert new root user.  */
+       ns->root_user = alloc_uid(ns, 0);
+       if (!ns->root_user) {
+               kfree(ns);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       /* Reset current->user with a new one */
+       new_user = alloc_uid(ns, current->uid);
+       if (!new_user) {
+               free_uid(ns->root_user);
+               kfree(ns);
+               return ERR_PTR(-ENOMEM);
+       }
+
+       switch_uid(new_user);
+       return ns;
+}
 
 struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
 {
@@ -28,7 +57,12 @@ struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
        BUG_ON(!old_ns);
        get_user_ns(old_ns);
 
-       new_ns = old_ns;
+       if (!(flags & CLONE_NEWUSER))
+               return old_ns;
+
+       new_ns = clone_user_ns(old_ns);
+
+       put_user_ns(old_ns);
        return new_ns;
 }
 
@@ -37,7 +71,7 @@ void free_user_ns(struct kref *kref)
        struct user_namespace *ns;
 
        ns = container_of(kref, struct user_namespace, kref);
+       release_uids(ns);
        kfree(ns);
 }
-
-#endif /* CONFIG_USER_NS */
+EXPORT_SYMBOL(free_user_ns);