[Devel] [PATCH 1/4] userns: let clone_uts_ns() handle setting uts->user_ns

[Serge E. Hallyn]

To do so we need to pass in the task_struct who'll get the utsname,
so we can get its user_ns.

Signed-off-by: Serge E. Hallyn <serge.hallyn at canonical.com>
---
 include/linux/utsname.h |   10 ++++++----
 kernel/nsproxy.c        |    7 +------
 kernel/utsname.c        |   12 +++++++-----
 3 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 85171be..165b17b 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -52,8 +52,9 @@ static inline void get_uts_ns(struct uts_namespace *ns)
 	kref_get(&ns->kref);
 }
 
-extern struct uts_namespace *copy_utsname(unsigned long flags,
-					struct uts_namespace *ns);
+extern struct uts_namespace *copy_utsname(struct task_struct *tsk,
+					  unsigned long flags,
+					  struct uts_namespace *ns);
 extern void free_uts_ns(struct kref *kref);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
@@ -69,8 +70,9 @@ static inline void put_uts_ns(struct uts_namespace *ns)
 {
 }
 
-static inline struct uts_namespace *copy_utsname(unsigned long flags,
-					struct uts_namespace *ns)
+static inline struct uts_namespace *copy_utsname(struct task_struct *tsk,
+						 unsigned long flags,
+						 struct uts_namespace *ns)
 {
 	if (flags & CLONE_NEWUTS)
 		return ERR_PTR(-EINVAL);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index b6dbff2..ffa6b67 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -69,16 +69,11 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		goto out_ns;
 	}
 
-	new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
+	new_nsp->uts_ns = copy_utsname(tsk, flags, tsk->nsproxy->uts_ns);
 	if (IS_ERR(new_nsp->uts_ns)) {
 		err = PTR_ERR(new_nsp->uts_ns);
 		goto out_uts;
 	}
-	if (new_nsp->uts_ns != tsk->nsproxy->uts_ns) {
-		put_user_ns(new_nsp->uts_ns->user_ns);
-		new_nsp->uts_ns->user_ns = task_cred_xxx(tsk, user)->user_ns;
-		get_user_ns(new_nsp->uts_ns->user_ns);
-	}
 
 	new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
 	if (IS_ERR(new_nsp->ipc_ns)) {
diff --git a/kernel/utsname.c b/kernel/utsname.c
index a7b3a8d..9462580 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -31,7 +31,8 @@ static struct uts_namespace *create_uts_ns(void)
  * @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 *clone_uts_ns(struct task_struct *tsk,
+					  struct uts_namespace *old_ns)
 {
 	struct uts_namespace *ns;
 
@@ -41,8 +42,7 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
 
 	down_read(&uts_sem);
 	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
-	ns->user_ns = old_ns->user_ns;
-	get_user_ns(ns->user_ns);
+	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
 	up_read(&uts_sem);
 	return ns;
 }
@@ -53,7 +53,9 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
  * utsname of this process won't be seen by parent, and vice
  * versa.
  */
-struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns)
+struct uts_namespace *copy_utsname(struct task_struct *tsk,
+				   unsigned long flags,
+				   struct uts_namespace *old_ns)
 {
 	struct uts_namespace *new_ns;
 
@@ -63,7 +65,7 @@ struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *ol
 	if (!(flags & CLONE_NEWUTS))
 		return old_ns;
 
-	new_ns = clone_uts_ns(old_ns);
+	new_ns = clone_uts_ns(tsk, old_ns);
 
 	put_uts_ns(old_ns);
 	return new_ns;
-- 
1.7.0.4

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