mqueue: Explicitly capture the user namespace to send the notification to.

Stop relying on user->user_ns which is going away and instead capture
the user_namespace of the process we are supposed to notify.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 28bd64ddeda3..b53cf3469d01 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -66,6 +66,7 @@ struct mqueue_inode_info {
 
         struct sigevent notify;
         struct pid* notify_owner;
+        struct user_namespace *notify_user_ns;
         struct user_struct *user;       /* user who created, for accounting */
         struct sock *notify_sock;
         struct sk_buff *notify_cookie;
@@ -139,6 +140,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
                 info->notify_owner = NULL;
+                info->notify_user_ns = NULL;
                 info->qsize = 0;
                 info->user = NULL;      /* set when all is ok */
                 memset(&info->attr, 0, sizeof(info->attr));
@@ -536,7 +538,7 @@ static void __do_notify(struct mqueue_inode_info *info)
                         rcu_read_lock();
                         sig_i.si_pid = task_tgid_nr_ns(current,
                                                 ns_of_pid(info->notify_owner));
-                        sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
+                        sig_i.si_uid = user_ns_map_uid(info->notify_user_ns,
                                                 current_cred(), current_uid());
                         rcu_read_unlock();
 
@@ -550,7 +552,9 @@ static void __do_notify(struct mqueue_inode_info *info)
                 }
                 /* after notification unregisters process */
                 put_pid(info->notify_owner);
+                put_user_ns(info->notify_user_ns);
                 info->notify_owner = NULL;
+                info->notify_user_ns = NULL;
         }
         wake_up(&info->wait_q);
 }
@@ -575,7 +579,9 @@ static void remove_notification(struct mqueue_inode_info *info)
                 netlink_sendskb(info->notify_sock, info->notify_cookie);
         }
         put_pid(info->notify_owner);
+        put_user_ns(info->notify_user_ns);
         info->notify_owner = NULL;
+        info->notify_user_ns = NULL;
 }
 
 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
@@ -1140,6 +1146,7 @@ retry:
                 }
 
                 info->notify_owner = get_pid(task_tgid(current));
+                info->notify_user_ns = get_user_ns(current_user_ns());
                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
         }
         spin_unlock(&info->lock);