[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.

Changelog:
        Feb 23: As per Oleg's coment, just pass in tsk.

Signed-off-by: Serge E. Hallyn <serge.hal...@canonical.com>
---
 include/linux/utsname.h |    6 +++---
 kernel/nsproxy.c        |    7 +------
 kernel/utsname.c        |   12 +++++++-----
 3 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 85171be..21b4566 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -53,7 +53,7 @@ static inline void get_uts_ns(struct uts_namespace *ns)
 }
 
 extern struct uts_namespace *copy_utsname(unsigned long flags,
-                                       struct uts_namespace *ns);
+                                         struct task_struct *tsk);
 extern void free_uts_ns(struct kref *kref);
 
 static inline void put_uts_ns(struct uts_namespace *ns)
@@ -70,12 +70,12 @@ static inline void put_uts_ns(struct uts_namespace *ns)
 }
 
 static inline struct uts_namespace *copy_utsname(unsigned long flags,
-                                       struct uts_namespace *ns)
+                                                struct task_struct *tsk)
 {
        if (flags & CLONE_NEWUTS)
                return ERR_PTR(-EINVAL);
 
-       return ns;
+       return tsk->nsproxy->uts_ns;
 }
 #endif
 
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index b6dbff2..ac8a56e 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(flags, tsk);
        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..4464617 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;
 }
@@ -53,8 +53,10 @@ 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(unsigned long flags,
+                                  struct task_struct *tsk)
 {
+       struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
        struct uts_namespace *new_ns;
 
        BUG_ON(!old_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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