IPC: consolidate all xxxctl_down() functions

semctl_down(), msgctl_down() and shmctl_down() are used to handle the same set
of commands for each kind of IPC.  They all start to do the same job (they
retrieve the ipc and do some permission checks) before handling the commands
on their own.

This patch proposes to consolidate this by moving these same pieces of code
into one common function called ipcctl_pre_down().

It simplifies a little these xxxctl_down() functions and increases a little
the maintainability.

Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 38 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
index e803abec2b08..d56d3ab6bb8a 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -141,21 +141,6 @@ void __init sem_init (void)
 }
 
 /*
- * This routine is called in the paths where the rw_mutex is held to protect
- * access to the idr tree.
- */
-static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
-                                                int id)
-{
-        struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
-
-        if (IS_ERR(ipcp))
-                return (struct sem_array *)ipcp;
-
-        return container_of(ipcp, struct sem_array, sem_perm);
-}
-
-/*
  * sem_lock_(check_) routines are called in the paths where the rw_mutex
  * is not held.
  */
@@ -878,31 +863,12 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
                 if (copy_semid_from_user(&semid64, arg.buf, version))
                         return -EFAULT;
         }
-        down_write(&sem_ids(ns).rw_mutex);
-        sma = sem_lock_check_down(ns, semid);
-        if (IS_ERR(sma)) {
-                err = PTR_ERR(sma);
-                goto out_up;
-        }
-
-        ipcp = &sma->sem_perm;
 
-        err = audit_ipc_obj(ipcp);
-        if (err)
-                goto out_unlock;
+        ipcp = ipcctl_pre_down(&sem_ids(ns), semid, cmd, &semid64.sem_perm, 0);
+        if (IS_ERR(ipcp))
+                return PTR_ERR(ipcp);
 
-        if (cmd == IPC_SET) {
-                err = audit_ipc_set_perm(0, semid64.sem_perm.uid,
-                                         semid64.sem_perm.gid,
-                                         semid64.sem_perm.mode);
-                if (err)
-                        goto out_unlock;
-        }
-        if (current->euid != ipcp->cuid && 
-            current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
-                err=-EPERM;
-                goto out_unlock;
-        }
+        sma = container_of(ipcp, struct sem_array, sem_perm);
 
         err = security_sem_semctl(sma, cmd);
         if (err)