userns: Convert ipc to use kuid and kgid where appropriate

- Store the ipc owner and creator with a kuid
- Store the ipc group and the crators group with a kgid.
- Add error handling to ipc_update_perms, allowing it to
  fail if the uids and gids can not be converted to kuids
  or kgids.
- Modify the proc files to display the ipc creator and
  owner in the user namespace of the opener of the proc file.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/ipc/msg.c b/ipc/msg.c
index 7385de25788a..a71af5a65abf 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -443,9 +443,12 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
                         goto out_unlock;
                 }
 
+                err = ipc_update_perm(&msqid64.msg_perm, ipcp);
+                if (err)
+                        goto out_unlock;
+
                 msq->q_qbytes = msqid64.msg_qbytes;
 
-                ipc_update_perm(&msqid64.msg_perm, ipcp);
                 msq->q_ctime = get_seconds();
                 /* sleeping receivers might be excluded by
                  * stricter permissions.
@@ -922,6 +925,7 @@ out:
 #ifdef CONFIG_PROC_FS
 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
 {
+        struct user_namespace *user_ns = seq_user_ns(s);
         struct msg_queue *msq = it;
 
         return seq_printf(s,
@@ -933,10 +937,10 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
                         msq->q_qnum,
                         msq->q_lspid,
                         msq->q_lrpid,
-                        msq->q_perm.uid,
-                        msq->q_perm.gid,
-                        msq->q_perm.cuid,
-                        msq->q_perm.cgid,
+                        from_kuid_munged(user_ns, msq->q_perm.uid),
+                        from_kgid_munged(user_ns, msq->q_perm.gid),
+                        from_kuid_munged(user_ns, msq->q_perm.cuid),
+                        from_kgid_munged(user_ns, msq->q_perm.cgid),
                         msq->q_stime,
                         msq->q_rtime,
                         msq->q_ctime);