1 files changed, 90 insertions, 45 deletions

diff --git a/kernel/utsname.c b/kernel/utsname.c
index c859164a699..fd393124e50 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -9,44 +9,50 @@
  *  License.
  */
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/uts.h>
 #include <linux/utsname.h>
-#include <linux/version.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/user_namespace.h>
+#include <linux/proc_ns.h>
 
-/*
- * Clone a new ns copying an original utsname, setting refcount to 1
- * @old_ns: namespace to clone
- * Return NULL on error (failure to kmalloc), new ns otherwise
- */
-static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
+static struct uts_namespace *create_uts_ns(void)
 {
-	struct uts_namespace *ns;
+	struct uts_namespace *uts_ns;
 
-	ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
-	if (ns) {
-		memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
-		kref_init(&ns->kref);
-	}
-	return ns;
+	uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
+	if (uts_ns)
+		kref_init(&uts_ns->kref);
+	return uts_ns;
 }
 
 /*
- * unshare the current process' utsname namespace.
- * called only in sys_unshare()
+ * Clone a new ns copying an original utsname, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
  */
-int unshare_utsname(unsigned long unshare_flags, struct uts_namespace **new_uts)
+static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
+					  struct uts_namespace *old_ns)
 {
-	if (unshare_flags & CLONE_NEWUTS) {
-		if (!capable(CAP_SYS_ADMIN))
-			return -EPERM;
+	struct uts_namespace *ns;
+	int err;
 
-		*new_uts = clone_uts_ns(current->nsproxy->uts_ns);
-		if (!*new_uts)
-			return -ENOMEM;
+	ns = create_uts_ns();
+	if (!ns)
+		return ERR_PTR(-ENOMEM);
+
+	err = proc_alloc_inum(&ns->proc_inum);
+	if (err) {
+		kfree(ns);
+		return ERR_PTR(err);
 	}
 
-	return 0;
+	down_read(&uts_sem);
+	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+	ns->user_ns = get_user_ns(user_ns);
+	up_read(&uts_sem);
+	return ns;
 }
 
 /*
@@ -55,35 +61,21 @@ int unshare_utsname(unsigned long unshare_flags, struct uts_namespace **new_uts)
  * utsname of this process won't be seen by parent, and vice
  * versa.
  */
-int copy_utsname(int flags, struct task_struct *tsk)
+struct uts_namespace *copy_utsname(unsigned long flags,
+	struct user_namespace *user_ns, struct uts_namespace *old_ns)
 {
-	struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
 	struct uts_namespace *new_ns;
-	int err = 0;
-
-	if (!old_ns)
-		return 0;
 
+	BUG_ON(!old_ns);
 	get_uts_ns(old_ns);
 
 	if (!(flags & CLONE_NEWUTS))
-		return 0;
+		return old_ns;
 
-	if (!capable(CAP_SYS_ADMIN)) {
-		err = -EPERM;
-		goto out;
-	}
+	new_ns = clone_uts_ns(user_ns, old_ns);
 
-	new_ns = clone_uts_ns(old_ns);
-	if (!new_ns) {
-		err = -ENOMEM;
-		goto out;
-	}
-	tsk->nsproxy->uts_ns = new_ns;
-
-out:
 	put_uts_ns(old_ns);
-	return err;
+	return new_ns;
 }
 
 void free_uts_ns(struct kref *kref)
@@ -91,5 +83,58 @@ void free_uts_ns(struct kref *kref)
 	struct uts_namespace *ns;
 
 	ns = container_of(kref, struct uts_namespace, kref);
+	put_user_ns(ns->user_ns);
+	proc_free_inum(ns->proc_inum);
 	kfree(ns);
 }
+
+static void *utsns_get(struct task_struct *task)
+{
+	struct uts_namespace *ns = NULL;
+	struct nsproxy *nsproxy;
+
+	rcu_read_lock();
+	nsproxy = task_nsproxy(task);
+	if (nsproxy) {
+		ns = nsproxy->uts_ns;
+		get_uts_ns(ns);
+	}
+	rcu_read_unlock();
+
+	return ns;
+}
+
+static void utsns_put(void *ns)
+{
+	put_uts_ns(ns);
+}
+
+static int utsns_install(struct nsproxy *nsproxy, void *new)
+{
+	struct uts_namespace *ns = new;
+
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+		return -EPERM;
+
+	get_uts_ns(ns);
+	put_uts_ns(nsproxy->uts_ns);
+	nsproxy->uts_ns = ns;
+	return 0;
+}
+
+static unsigned int utsns_inum(void *vp)
+{
+	struct uts_namespace *ns = vp;
+
+	return ns->proc_inum;
+}
+
+const struct proc_ns_operations utsns_operations = {
+	.name		= "uts",
+	.type		= CLONE_NEWUTS,
+	.get		= utsns_get,
+	.put		= utsns_put,
+	.install	= utsns_install,
+	.inum		= utsns_inum,
+};