msgctl(): split the actual work from copyin/copyout

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/ipc/msg.c b/ipc/msg.c
index 5b25e07..322e7bf 100644 (file)
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -361,23 +361,17 @@ copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
  * NOTE: no locks must be held, the rwsem is taken inside this function.
  */
 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
-                      struct msqid_ds __user *buf, int version)
+                       struct msqid64_ds *msqid64)
 {
        struct kern_ipc_perm *ipcp;
-       struct msqid64_ds uninitialized_var(msqid64);
        struct msg_queue *msq;
        int err;
 
-       if (cmd == IPC_SET) {
-               if (copy_msqid_from_user(&msqid64, buf, version))
-                       return -EFAULT;
-       }
-
        down_write(&msg_ids(ns).rwsem);
        rcu_read_lock();
 
        ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
-                                     &msqid64.msg_perm, msqid64.msg_qbytes);
+                                     &msqid64->msg_perm, msqid64->msg_qbytes);
        if (IS_ERR(ipcp)) {
                err = PTR_ERR(ipcp);
                goto out_unlock1;
@@ -399,18 +393,18 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
        {
                DEFINE_WAKE_Q(wake_q);
 
-               if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
+               if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
                    !capable(CAP_SYS_RESOURCE)) {
                        err = -EPERM;
                        goto out_unlock1;
                }
 
                ipc_lock_object(&msq->q_perm);
-               err = ipc_update_perm(&msqid64.msg_perm, ipcp);
+               err = ipc_update_perm(&msqid64->msg_perm, ipcp);
                if (err)
                        goto out_unlock0;
 
-               msq->q_qbytes = msqid64.msg_qbytes;
+               msq->q_qbytes = msqid64->msg_qbytes;
 
                msq->q_ctime = get_seconds();
                /*
@@ -442,111 +436,89 @@ out_up:
        return err;
 }
 
-static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
-                        int cmd, int version, void __user *buf)
+static int msgctl_info(struct ipc_namespace *ns, int msqid,
+                        int cmd, struct msginfo *msginfo)
 {
        int err;
-       struct msg_queue *msq;
-
-       switch (cmd) {
-       case IPC_INFO:
-       case MSG_INFO:
-       {
-               struct msginfo msginfo;
-               int max_id;
-
-               if (!buf)
-                       return -EFAULT;
+       int max_id;
 
-               /*
-                * We must not return kernel stack data.
-                * due to padding, it's not enough
-                * to set all member fields.
-                */
-               err = security_msg_queue_msgctl(NULL, cmd);
-               if (err)
-                       return err;
-
-               memset(&msginfo, 0, sizeof(msginfo));
-               msginfo.msgmni = ns->msg_ctlmni;
-               msginfo.msgmax = ns->msg_ctlmax;
-               msginfo.msgmnb = ns->msg_ctlmnb;
-               msginfo.msgssz = MSGSSZ;
-               msginfo.msgseg = MSGSEG;
-               down_read(&msg_ids(ns).rwsem);
-               if (cmd == MSG_INFO) {
-                       msginfo.msgpool = msg_ids(ns).in_use;
-                       msginfo.msgmap = atomic_read(&ns->msg_hdrs);
-                       msginfo.msgtql = atomic_read(&ns->msg_bytes);
-               } else {
-                       msginfo.msgmap = MSGMAP;
-                       msginfo.msgpool = MSGPOOL;
-                       msginfo.msgtql = MSGTQL;
-               }
-               max_id = ipc_get_maxid(&msg_ids(ns));
-               up_read(&msg_ids(ns).rwsem);
-               if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
-                       return -EFAULT;
-               return (max_id < 0) ? 0 : max_id;
+       /*
+        * We must not return kernel stack data.
+        * due to padding, it's not enough
+        * to set all member fields.
+        */
+       err = security_msg_queue_msgctl(NULL, cmd);
+       if (err)
+               return err;
+
+       memset(msginfo, 0, sizeof(*msginfo));
+       msginfo->msgmni = ns->msg_ctlmni;
+       msginfo->msgmax = ns->msg_ctlmax;
+       msginfo->msgmnb = ns->msg_ctlmnb;
+       msginfo->msgssz = MSGSSZ;
+       msginfo->msgseg = MSGSEG;
+       down_read(&msg_ids(ns).rwsem);
+       if (cmd == MSG_INFO) {
+               msginfo->msgpool = msg_ids(ns).in_use;
+               msginfo->msgmap = atomic_read(&ns->msg_hdrs);
+               msginfo->msgtql = atomic_read(&ns->msg_bytes);
+       } else {
+               msginfo->msgmap = MSGMAP;
+               msginfo->msgpool = MSGPOOL;
+               msginfo->msgtql = MSGTQL;
        }
+       max_id = ipc_get_maxid(&msg_ids(ns));
+       up_read(&msg_ids(ns).rwsem);
+       return (max_id < 0) ? 0 : max_id;
+}
 
-       case MSG_STAT:
-       case IPC_STAT:
-       {
-               struct msqid64_ds tbuf;
-               int success_return;
-
-               if (!buf)
-                       return -EFAULT;
-
-               memset(&tbuf, 0, sizeof(tbuf));
+static int msgctl_stat(struct ipc_namespace *ns, int msqid,
+                        int cmd, struct msqid64_ds *p)
+{
+       int err;
+       struct msg_queue *msq;
+       int success_return;
 
-               rcu_read_lock();
-               if (cmd == MSG_STAT) {
-                       msq = msq_obtain_object(ns, msqid);
-                       if (IS_ERR(msq)) {
-                               err = PTR_ERR(msq);
-                               goto out_unlock;
-                       }
-                       success_return = msq->q_perm.id;
-               } else {
-                       msq = msq_obtain_object_check(ns, msqid);
-                       if (IS_ERR(msq)) {
-                               err = PTR_ERR(msq);
-                               goto out_unlock;
-                       }
-                       success_return = 0;
-               }
+       memset(p, 0, sizeof(*p));
 
-               err = -EACCES;
-               if (ipcperms(ns, &msq->q_perm, S_IRUGO))
+       rcu_read_lock();
+       if (cmd == MSG_STAT) {
+               msq = msq_obtain_object(ns, msqid);
+               if (IS_ERR(msq)) {
+                       err = PTR_ERR(msq);
                        goto out_unlock;
-
-               err = security_msg_queue_msgctl(msq, cmd);
-               if (err)
+               }
+               success_return = msq->q_perm.id;
+       } else {
+               msq = msq_obtain_object_check(ns, msqid);
+               if (IS_ERR(msq)) {
+                       err = PTR_ERR(msq);
                        goto out_unlock;
+               }
+               success_return = 0;
+       }
 
-               kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
-               tbuf.msg_stime  = msq->q_stime;
-               tbuf.msg_rtime  = msq->q_rtime;
-               tbuf.msg_ctime  = msq->q_ctime;
-               tbuf.msg_cbytes = msq->q_cbytes;
-               tbuf.msg_qnum   = msq->q_qnum;
-               tbuf.msg_qbytes = msq->q_qbytes;
-               tbuf.msg_lspid  = msq->q_lspid;
-               tbuf.msg_lrpid  = msq->q_lrpid;
-               rcu_read_unlock();
+       err = -EACCES;
+       if (ipcperms(ns, &msq->q_perm, S_IRUGO))
+               goto out_unlock;
 
-               if (copy_msqid_to_user(buf, &tbuf, version))
-                       return -EFAULT;
-               return success_return;
-       }
+       err = security_msg_queue_msgctl(msq, cmd);
+       if (err)
+               goto out_unlock;
+
+       kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
+       p->msg_stime  = msq->q_stime;
+       p->msg_rtime  = msq->q_rtime;
+       p->msg_ctime  = msq->q_ctime;
+       p->msg_cbytes = msq->q_cbytes;
+       p->msg_qnum   = msq->q_qnum;
+       p->msg_qbytes = msq->q_qbytes;
+       p->msg_lspid  = msq->q_lspid;
+       p->msg_lrpid  = msq->q_lrpid;
+       rcu_read_unlock();
 
-       default:
-               return -EINVAL;
-       }
+       return success_return;
 
-       return err;
 out_unlock:
        rcu_read_unlock();
        return err;
@@ -556,6 +528,8 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 {
        int version;
        struct ipc_namespace *ns;
+       struct msqid64_ds msqid64;
+       int err;
 
        if (msqid < 0 || cmd < 0)
                return -EINVAL;
@@ -565,13 +539,29 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 
        switch (cmd) {
        case IPC_INFO:
-       case MSG_INFO:
+       case MSG_INFO: {
+               struct msginfo msginfo;
+               err = msgctl_info(ns, msqid, cmd, &msginfo);
+               if (err < 0)
+                       return err;
+               if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
+                       err = -EFAULT;
+               return err;
+       }
        case MSG_STAT:  /* msqid is an index rather than a msg queue id */
        case IPC_STAT:
-               return msgctl_nolock(ns, msqid, cmd, version, buf);
+               err = msgctl_stat(ns, msqid, cmd, &msqid64);
+               if (err < 0)
+                       return err;
+               if (copy_msqid_to_user(buf, &msqid64, version))
+                       err = -EFAULT;
+               return err;
        case IPC_SET:
+               if (copy_msqid_from_user(&msqid64, buf, version))
+                       return -EFAULT;
+               /* fallthru */
        case IPC_RMID:
-               return msgctl_down(ns, msqid, cmd, buf, version);
+               return msgctl_down(ns, msqid, cmd, &msqid64);
        default:
                return  -EINVAL;
        }