10 files changed, 533 insertions, 369 deletions

diff --git a/ipc/Makefile b/ipc/Makefile
index 5fc5e33ea04..65c38439580 100644
--- a/ipc/Makefile
+++ b/ipc/Makefile
@@ -3,7 +3,7 @@
 #
 
 obj-$(CONFIG_SYSVIPC_COMPAT) += compat.o
-obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o
+obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o ipcns_notifier.o
 obj-$(CONFIG_SYSVIPC_SYSCTL) += ipc_sysctl.o
 obj_mq-$(CONFIG_COMPAT) += compat_mq.o
 obj-$(CONFIG_POSIX_MQUEUE) += mqueue.o msgutil.o $(obj_mq-y)
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 7f4235bed51..d3497465cc0 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -15,6 +15,8 @@
 #include <linux/sysctl.h>
 #include <linux/uaccess.h>
 #include <linux/ipc_namespace.h>
+#include <linux/msg.h>
+#include "util.h"
 
 static void *get_ipc(ctl_table *table)
 {
@@ -24,6 +26,27 @@ static void *get_ipc(ctl_table *table)
 	return which;
 }
 
+/*
+ * Routine that is called when a tunable has successfully been changed by
+ * hand and it has a callback routine registered on the ipc namespace notifier
+ * chain: we don't want such tunables to be recomputed anymore upon memory
+ * add/remove or ipc namespace creation/removal.
+ * They can come back to a recomputable state by being set to a <0 value.
+ */
+static void tunable_set_callback(int val)
+{
+	if (val >= 0)
+		unregister_ipcns_notifier(current->nsproxy->ipc_ns);
+	else {
+		/*
+		 * Re-enable automatic recomputing only if not already
+		 * enabled.
+		 */
+		recompute_msgmni(current->nsproxy->ipc_ns);
+		cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
+	}
+}
+
 #ifdef CONFIG_PROC_FS
 static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
 	void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -35,6 +58,24 @@ static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
 	return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
 }
 
+static int proc_ipc_callback_dointvec(ctl_table *table, int write,
+	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table ipc_table;
+	size_t lenp_bef = *lenp;
+	int rc;
+
+	memcpy(&ipc_table, table, sizeof(ipc_table));
+	ipc_table.data = get_ipc(table);
+
+	rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
+
+	if (write && !rc && lenp_bef == *lenp)
+		tunable_set_callback(*((int *)(ipc_table.data)));
+
+	return rc;
+}
+
 static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
 	struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -49,6 +90,7 @@ static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
 #else
 #define proc_ipc_doulongvec_minmax NULL
 #define proc_ipc_dointvec	   NULL
+#define proc_ipc_callback_dointvec NULL
 #endif
 
 #ifdef CONFIG_SYSCTL_SYSCALL
@@ -90,8 +132,30 @@ static int sysctl_ipc_data(ctl_table *table, int __user *name, int nlen,
 	}
 	return 1;
 }
+
+static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
+		int nlen, void __user *oldval, size_t __user *oldlenp,
+		void __user *newval, size_t newlen)
+{
+	int rc;
+
+	rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
+		newlen);
+
+	if (newval && newlen && rc > 0) {
+		/*
+		 * Tunable has successfully been changed from userland
+		 */
+		int *data = get_ipc(table);
+
+		tunable_set_callback(*data);
+	}
+
+	return rc;
+}
 #else
 #define sysctl_ipc_data NULL
+#define sysctl_ipc_registered_data NULL
 #endif
 
 static struct ctl_table ipc_kern_table[] = {
@@ -137,8 +201,8 @@ static struct ctl_table ipc_kern_table[] = {
 		.data		= &init_ipc_ns.msg_ctlmni,
 		.maxlen		= sizeof (init_ipc_ns.msg_ctlmni),
 		.mode		= 0644,
-		.proc_handler	= proc_ipc_dointvec,
-		.strategy	= sysctl_ipc_data,
+		.proc_handler	= proc_ipc_callback_dointvec,
+		.strategy	= sysctl_ipc_registered_data,
 	},
 	{
 		.ctl_name	= KERN_MSGMNB,
diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
new file mode 100644
index 00000000000..70ff09183f7
--- /dev/null
+++ b/ipc/ipcns_notifier.c
@@ -0,0 +1,82 @@
+/*
+ * linux/ipc/ipcns_notifier.c
+ * Copyright (C) 2007 BULL SA. Nadia Derbey
+ *
+ * Notification mechanism for ipc namespaces:
+ * The callback routine registered in the memory chain invokes the ipcns
+ * notifier chain with the IPCNS_MEMCHANGED event.
+ * Each callback routine registered in the ipcns namespace recomputes msgmni
+ * for the owning namespace.
+ */
+
+#include <linux/msg.h>
+#include <linux/rcupdate.h>
+#include <linux/notifier.h>
+#include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
+
+#include "util.h"
+
+
+
+static BLOCKING_NOTIFIER_HEAD(ipcns_chain);
+
+
+static int ipcns_callback(struct notifier_block *self,
+				unsigned long action, void *arg)
+{
+	struct ipc_namespace *ns;
+
+	switch (action) {
+	case IPCNS_MEMCHANGED:   /* amount of lowmem has changed */
+	case IPCNS_CREATED:
+	case IPCNS_REMOVED:
+		/*
+		 * It's time to recompute msgmni
+		 */
+		ns = container_of(self, struct ipc_namespace, ipcns_nb);
+		/*
+		 * No need to get a reference on the ns: the 1st job of
+		 * free_ipc_ns() is to unregister the callback routine.
+		 * blocking_notifier_chain_unregister takes the wr lock to do
+		 * it.
+		 * When this callback routine is called the rd lock is held by
+		 * blocking_notifier_call_chain.
+		 * So the ipc ns cannot be freed while we are here.
+		 */
+		recompute_msgmni(ns);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+int register_ipcns_notifier(struct ipc_namespace *ns)
+{
+	memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
+	ns->ipcns_nb.notifier_call = ipcns_callback;
+	ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
+	return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
+}
+
+int cond_register_ipcns_notifier(struct ipc_namespace *ns)
+{
+	memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
+	ns->ipcns_nb.notifier_call = ipcns_callback;
+	ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
+	return blocking_notifier_chain_cond_register(&ipcns_chain,
+							&ns->ipcns_nb);
+}
+
+int unregister_ipcns_notifier(struct ipc_namespace *ns)
+{
+	return blocking_notifier_chain_unregister(&ipcns_chain,
+						&ns->ipcns_nb);
+}
+
+int ipcns_notify(unsigned long val)
+{
+	return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
+}
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 94fd3b08fb7..b3b69fd5133 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -673,7 +673,7 @@ asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 	if (IS_ERR(name = getname(u_name)))
 		return PTR_ERR(name);
 
-	fd = get_unused_fd();
+	fd = get_unused_fd_flags(O_CLOEXEC);
 	if (fd < 0)
 		goto out_putname;
 
@@ -709,7 +709,6 @@ asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
 		goto out_putfd;
 	}
 
-	set_close_on_exec(fd, 1);
 	fd_install(fd, filp);
 	goto out_upsem;
 
diff --git a/ipc/msg.c b/ipc/msg.c
index 46585a05473..32494e8cc7a 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -27,6 +27,7 @@
 #include <linux/msg.h>
 #include <linux/spinlock.h>
 #include <linux/init.h>
+#include <linux/mm.h>
 #include <linux/proc_fs.h>
 #include <linux/list.h>
 #include <linux/security.h>
@@ -70,7 +71,6 @@ struct msg_sender {
 #define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
 
 #define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
-#define msg_buildid(id, seq)	ipc_buildid(id, seq)
 
 static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
 static int newque(struct ipc_namespace *, struct ipc_params *);
@@ -78,11 +78,49 @@ static int newque(struct ipc_namespace *, struct ipc_params *);
 static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
 #endif
 
+/*
+ * Scale msgmni with the available lowmem size: the memory dedicated to msg
+ * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
+ * Also take into account the number of nsproxies created so far.
+ * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
+ */
+void recompute_msgmni(struct ipc_namespace *ns)
+{
+	struct sysinfo i;
+	unsigned long allowed;
+	int nb_ns;
+
+	si_meminfo(&i);
+	allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
+		/ MSGMNB;
+	nb_ns = atomic_read(&nr_ipc_ns);
+	allowed /= nb_ns;
+
+	if (allowed < MSGMNI) {
+		ns->msg_ctlmni = MSGMNI;
+		goto out_callback;
+	}
+
+	if (allowed > IPCMNI / nb_ns) {
+		ns->msg_ctlmni = IPCMNI / nb_ns;
+		goto out_callback;
+	}
+
+	ns->msg_ctlmni = allowed;
+
+out_callback:
+
+	printk(KERN_INFO "msgmni has been set to %d for ipc namespace %p\n",
+		ns->msg_ctlmni, ns);
+}
+
 void msg_init_ns(struct ipc_namespace *ns)
 {
 	ns->msg_ctlmax = MSGMAX;
 	ns->msg_ctlmnb = MSGMNB;
-	ns->msg_ctlmni = MSGMNI;
+
+	recompute_msgmni(ns);
+
 	atomic_set(&ns->msg_bytes, 0);
 	atomic_set(&ns->msg_hdrs, 0);
 	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
@@ -104,21 +142,6 @@ void __init msg_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 msg_queue *msg_lock_check_down(struct ipc_namespace *ns,
-						int id)
-{
-	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id);
-
-	if (IS_ERR(ipcp))
-		return (struct msg_queue *)ipcp;
-
-	return container_of(ipcp, struct msg_queue, q_perm);
-}
-
-/*
  * msg_lock_(check_) routines are called in the paths where the rw_mutex
  * is not held.
  */
@@ -186,7 +209,6 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 		return id;
 	}
 
-	msq->q_perm.id = msg_buildid(id, msq->q_perm.seq);
 	msq->q_stime = msq->q_rtime = 0;
 	msq->q_ctime = get_seconds();
 	msq->q_cbytes = msq->q_qnum = 0;
@@ -324,19 +346,19 @@ copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 		out.msg_rtime		= in->msg_rtime;
 		out.msg_ctime		= in->msg_ctime;
 
-		if (in->msg_cbytes > USHRT_MAX)
-			out.msg_cbytes	= USHRT_MAX;
+		if (in->msg_cbytes > USHORT_MAX)
+			out.msg_cbytes	= USHORT_MAX;
 		else
 			out.msg_cbytes	= in->msg_cbytes;
 		out.msg_lcbytes		= in->msg_cbytes;
 
-		if (in->msg_qnum > USHRT_MAX)
-			out.msg_qnum	= USHRT_MAX;
+		if (in->msg_qnum > USHORT_MAX)
+			out.msg_qnum	= USHORT_MAX;
 		else
 			out.msg_qnum	= in->msg_qnum;
 
-		if (in->msg_qbytes > USHRT_MAX)
-			out.msg_qbytes	= USHRT_MAX;
+		if (in->msg_qbytes > USHORT_MAX)
+			out.msg_qbytes	= USHORT_MAX;
 		else
 			out.msg_qbytes	= in->msg_qbytes;
 		out.msg_lqbytes		= in->msg_qbytes;
@@ -351,31 +373,14 @@ copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 	}
 }
 
-struct msq_setbuf {
-	unsigned long	qbytes;
-	uid_t		uid;
-	gid_t		gid;
-	mode_t		mode;
-};
-
 static inline unsigned long
-copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
+copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 {
 	switch(version) {
 	case IPC_64:
-	{
-		struct msqid64_ds tbuf;
-
-		if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
+		if (copy_from_user(out, buf, sizeof(*out)))
 			return -EFAULT;
-
-		out->qbytes		= tbuf.msg_qbytes;
-		out->uid		= tbuf.msg_perm.uid;
-		out->gid		= tbuf.msg_perm.gid;
-		out->mode		= tbuf.msg_perm.mode;
-
 		return 0;
-	}
 	case IPC_OLD:
 	{
 		struct msqid_ds tbuf_old;
@@ -383,14 +388,14 @@ copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
 		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 			return -EFAULT;
 
-		out->uid		= tbuf_old.msg_perm.uid;
-		out->gid		= tbuf_old.msg_perm.gid;
-		out->mode		= tbuf_old.msg_perm.mode;
+		out->msg_perm.uid      	= tbuf_old.msg_perm.uid;
+		out->msg_perm.gid      	= tbuf_old.msg_perm.gid;
+		out->msg_perm.mode     	= tbuf_old.msg_perm.mode;
 
 		if (tbuf_old.msg_qbytes == 0)
-			out->qbytes	= tbuf_old.msg_lqbytes;
+			out->msg_qbytes	= tbuf_old.msg_lqbytes;
 		else
-			out->qbytes	= tbuf_old.msg_qbytes;
+			out->msg_qbytes	= tbuf_old.msg_qbytes;
 
 		return 0;
 	}
@@ -399,10 +404,71 @@ copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
 	}
 }
 
-asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
+/*
+ * This function handles some msgctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex 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 kern_ipc_perm *ipcp;
-	struct msq_setbuf uninitialized_var(setbuf);
+	struct msqid64_ds msqid64;
+	struct msg_queue *msq;
+	int err;
+
+	if (cmd == IPC_SET) {
+		if (copy_msqid_from_user(&msqid64, buf, version))
+			return -EFAULT;
+	}
+
+	ipcp = ipcctl_pre_down(&msg_ids(ns), msqid, cmd,
+			       &msqid64.msg_perm, msqid64.msg_qbytes);
+	if (IS_ERR(ipcp))
+		return PTR_ERR(ipcp);
+
+	msq = container_of(ipcp, struct msg_queue, q_perm);
+
+	err = security_msg_queue_msgctl(msq, cmd);
+	if (err)
+		goto out_unlock;
+
+	switch (cmd) {
+	case IPC_RMID:
+		freeque(ns, ipcp);
+		goto out_up;
+	case IPC_SET:
+		if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
+		    !capable(CAP_SYS_RESOURCE)) {
+			err = -EPERM;
+			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.
+		 */
+		expunge_all(msq, -EAGAIN);
+		/* sleeping senders might be able to send
+		 * due to a larger queue size.
+		 */
+		ss_wakeup(&msq->q_senders, 0);
+		break;
+	default:
+		err = -EINVAL;
+	}
+out_unlock:
+	msg_unlock(msq);
+out_up:
+	up_write(&msg_ids(ns).rw_mutex);
+	return err;
+}
+
+asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
+{
 	struct msg_queue *msq;
 	int err, version;
 	struct ipc_namespace *ns;
@@ -498,82 +564,13 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
 		return success_return;
 	}
 	case IPC_SET:
-		if (!buf)
-			return -EFAULT;
-		if (copy_msqid_from_user(&setbuf, buf, version))
-			return -EFAULT;
-		break;
 	case IPC_RMID:
-		break;
+		err = msgctl_down(ns, msqid, cmd, buf, version);
+		return err;
 	default:
 		return  -EINVAL;
 	}
 
-	down_write(&msg_ids(ns).rw_mutex);
-	msq = msg_lock_check_down(ns, msqid);
-	if (IS_ERR(msq)) {
-		err = PTR_ERR(msq);
-		goto out_up;
-	}
-
-	ipcp = &msq->q_perm;
-
-	err = audit_ipc_obj(ipcp);
-	if (err)
-		goto out_unlock_up;
-	if (cmd == IPC_SET) {
-		err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid,
-					 setbuf.mode);
-		if (err)
-			goto out_unlock_up;
-	}
-
-	err = -EPERM;
-	if (current->euid != ipcp->cuid &&
-	    current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
-		/* We _could_ check for CAP_CHOWN above, but we don't */
-		goto out_unlock_up;
-
-	err = security_msg_queue_msgctl(msq, cmd);
-	if (err)
-		goto out_unlock_up;
-
-	switch (cmd) {
-	case IPC_SET:
-	{
-		err = -EPERM;
-		if (setbuf.qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
-			goto out_unlock_up;
-
-		msq->q_qbytes = setbuf.qbytes;
-
-		ipcp->uid = setbuf.uid;
-		ipcp->gid = setbuf.gid;
-		ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
-			     (S_IRWXUGO & setbuf.mode);
-		msq->q_ctime = get_seconds();
-		/* sleeping receivers might be excluded by
-		 * stricter permissions.
-		 */
-		expunge_all(msq, -EAGAIN);
-		/* sleeping senders might be able to send
-		 * due to a larger queue size.
-		 */
-		ss_wakeup(&msq->q_senders, 0);
-		msg_unlock(msq);
-		break;
-	}
-	case IPC_RMID:
-		freeque(ns, &msq->q_perm);
-		break;
-	}
-	err = 0;
-out_up:
-	up_write(&msg_ids(ns).rw_mutex);
-	return err;
-out_unlock_up:
-	msg_unlock(msq);
-	goto out_up;
 out_unlock:
 	msg_unlock(msq);
 	return err;
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 1b967655eb3..9171d948751 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -20,10 +20,20 @@ static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
 	if (ns == NULL)
 		return ERR_PTR(-ENOMEM);
 
+	atomic_inc(&nr_ipc_ns);
+
 	sem_init_ns(ns);
 	msg_init_ns(ns);
 	shm_init_ns(ns);
 
+	/*
+	 * msgmni has already been computed for the new ipc ns.
+	 * Thus, do the ipcns creation notification before registering that
+	 * new ipcns in the chain.
+	 */
+	ipcns_notify(IPCNS_CREATED);
+	register_ipcns_notifier(ns);
+
 	kref_init(&ns->kref);
 	return ns;
 }
@@ -79,8 +89,24 @@ void free_ipc_ns(struct kref *kref)
 	struct ipc_namespace *ns;
 
 	ns = container_of(kref, struct ipc_namespace, kref);
+	/*
+	 * Unregistering the hotplug notifier at the beginning guarantees
+	 * that the ipc namespace won't be freed while we are inside the
+	 * callback routine. Since the blocking_notifier_chain_XXX routines
+	 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
+	 * won't take the rw lock before blocking_notifier_call_chain() has
+	 * released the rd lock.
+	 */
+	unregister_ipcns_notifier(ns);
 	sem_exit_ns(ns);
 	msg_exit_ns(ns);
 	shm_exit_ns(ns);
 	kfree(ns);
+	atomic_dec(&nr_ipc_ns);
+
+	/*
+	 * Do the ipcns removal notification after decrementing nr_ipc_ns in
+	 * order to have a correct value when recomputing msgmni.
+	 */
+	ipcns_notify(IPCNS_REMOVED);
 }
diff --git a/ipc/sem.c b/ipc/sem.c
index 0b45a4d383c..e9418df5ff3 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -91,7 +91,6 @@
 
 #define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
 #define sem_checkid(sma, semid)	ipc_checkid(&sma->sem_perm, semid)
-#define sem_buildid(id, seq)	ipc_buildid(id, seq)
 
 static int newary(struct ipc_namespace *, struct ipc_params *);
 static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
@@ -142,21 +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.
  */
@@ -181,6 +165,25 @@ static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
 	return container_of(ipcp, struct sem_array, sem_perm);
 }
 
+static inline void sem_lock_and_putref(struct sem_array *sma)
+{
+	ipc_lock_by_ptr(&sma->sem_perm);
+	ipc_rcu_putref(sma);
+}
+
+static inline void sem_getref_and_unlock(struct sem_array *sma)
+{
+	ipc_rcu_getref(sma);
+	ipc_unlock(&(sma)->sem_perm);
+}
+
+static inline void sem_putref(struct sem_array *sma)
+{
+	ipc_lock_by_ptr(&sma->sem_perm);
+	ipc_rcu_putref(sma);
+	ipc_unlock(&(sma)->sem_perm);
+}
+
 static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
 {
 	ipc_rmid(&sem_ids(ns), &s->sem_perm);
@@ -268,7 +271,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
 	}
 	ns->used_sems += nsems;
 
-	sma->sem_perm.id = sem_buildid(id, sma->sem_perm.seq);
 	sma->sem_base = (struct sem *) &sma[1];
 	/* sma->sem_pending = NULL; */
 	sma->sem_pending_last = &sma->sem_pending;
@@ -700,19 +702,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 		int i;
 
 		if(nsems > SEMMSL_FAST) {
-			ipc_rcu_getref(sma);
-			sem_unlock(sma);			
+			sem_getref_and_unlock(sma);
 
 			sem_io = ipc_alloc(sizeof(ushort)*nsems);
 			if(sem_io == NULL) {
-				ipc_lock_by_ptr(&sma->sem_perm);
-				ipc_rcu_putref(sma);
-				sem_unlock(sma);
+				sem_putref(sma);
 				return -ENOMEM;
 			}
 
-			ipc_lock_by_ptr(&sma->sem_perm);
-			ipc_rcu_putref(sma);
+			sem_lock_and_putref(sma);
 			if (sma->sem_perm.deleted) {
 				sem_unlock(sma);
 				err = -EIDRM;
@@ -733,38 +731,30 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 		int i;
 		struct sem_undo *un;
 
-		ipc_rcu_getref(sma);
-		sem_unlock(sma);
+		sem_getref_and_unlock(sma);
 
 		if(nsems > SEMMSL_FAST) {
 			sem_io = ipc_alloc(sizeof(ushort)*nsems);
 			if(sem_io == NULL) {
-				ipc_lock_by_ptr(&sma->sem_perm);
-				ipc_rcu_putref(sma);
-				sem_unlock(sma);
+				sem_putref(sma);
 				return -ENOMEM;
 			}
 		}
 
 		if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
-			ipc_lock_by_ptr(&sma->sem_perm);
-			ipc_rcu_putref(sma);
-			sem_unlock(sma);
+			sem_putref(sma);
 			err = -EFAULT;
 			goto out_free;
 		}
 
 		for (i = 0; i < nsems; i++) {
 			if (sem_io[i] > SEMVMX) {
-				ipc_lock_by_ptr(&sma->sem_perm);
-				ipc_rcu_putref(sma);
-				sem_unlock(sma);
+				sem_putref(sma);
 				err = -ERANGE;
 				goto out_free;
 			}
 		}
-		ipc_lock_by_ptr(&sma->sem_perm);
-		ipc_rcu_putref(sma);
+		sem_lock_and_putref(sma);
 		if (sma->sem_perm.deleted) {
 			sem_unlock(sma);
 			err = -EIDRM;
@@ -830,28 +820,14 @@ out_free:
 	return err;
 }
 
-struct sem_setbuf {
-	uid_t	uid;
-	gid_t	gid;
-	mode_t	mode;
-};
-
-static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
+static inline unsigned long
+copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
 {
 	switch(version) {
 	case IPC_64:
-	    {
-		struct semid64_ds tbuf;
-
-		if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
+		if (copy_from_user(out, buf, sizeof(*out)))
 			return -EFAULT;
-
-		out->uid	= tbuf.sem_perm.uid;
-		out->gid	= tbuf.sem_perm.gid;
-		out->mode	= tbuf.sem_perm.mode;
-
 		return 0;
-	    }
 	case IPC_OLD:
 	    {
 		struct semid_ds tbuf_old;
@@ -859,9 +835,9 @@ static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __
 		if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 			return -EFAULT;
 
-		out->uid	= tbuf_old.sem_perm.uid;
-		out->gid	= tbuf_old.sem_perm.gid;
-		out->mode	= tbuf_old.sem_perm.mode;
+		out->sem_perm.uid	= tbuf_old.sem_perm.uid;
+		out->sem_perm.gid	= tbuf_old.sem_perm.gid;
+		out->sem_perm.mode	= tbuf_old.sem_perm.mode;
 
 		return 0;
 	    }
@@ -870,38 +846,29 @@ static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __
 	}
 }
 
-static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
-		int cmd, int version, union semun arg)
+/*
+ * This function handles some semctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex is taken inside this function.
+ */
+static int semctl_down(struct ipc_namespace *ns, int semid,
+		       int cmd, int version, union semun arg)
 {
 	struct sem_array *sma;
 	int err;
-	struct sem_setbuf uninitialized_var(setbuf);
+	struct semid64_ds semid64;
 	struct kern_ipc_perm *ipcp;
 
 	if(cmd == IPC_SET) {
-		if(copy_semid_from_user (&setbuf, arg.buf, version))
+		if (copy_semid_from_user(&semid64, arg.buf, version))
 			return -EFAULT;
 	}
-	sma = sem_lock_check_down(ns, semid);
-	if (IS_ERR(sma))
-		return PTR_ERR(sma);
 
-	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, setbuf.uid, setbuf.gid, setbuf.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)
@@ -910,26 +877,19 @@ static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
 	switch(cmd){
 	case IPC_RMID:
 		freeary(ns, ipcp);
-		err = 0;
-		break;
+		goto out_up;
 	case IPC_SET:
-		ipcp->uid = setbuf.uid;
-		ipcp->gid = setbuf.gid;
-		ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
-				| (setbuf.mode & S_IRWXUGO);
+		ipc_update_perm(&semid64.sem_perm, ipcp);
 		sma->sem_ctime = get_seconds();
-		sem_unlock(sma);
-		err = 0;
 		break;
 	default:
-		sem_unlock(sma);
 		err = -EINVAL;
-		break;
 	}
-	return err;
 
 out_unlock:
 	sem_unlock(sma);
+out_up:
+	up_write(&sem_ids(ns).rw_mutex);
 	return err;
 }
 
@@ -963,9 +923,7 @@ asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
 		return err;
 	case IPC_RMID:
 	case IPC_SET:
-		down_write(&sem_ids(ns).rw_mutex);
-		err = semctl_down(ns,semid,semnum,cmd,version,arg);
-		up_write(&sem_ids(ns).rw_mutex);
+		err = semctl_down(ns, semid, cmd, version, arg);
 		return err;
 	default:
 		return -EINVAL;
@@ -1044,14 +1002,11 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
 		return ERR_PTR(PTR_ERR(sma));
 
 	nsems = sma->sem_nsems;
-	ipc_rcu_getref(sma);
-	sem_unlock(sma);
+	sem_getref_and_unlock(sma);
 
 	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
 	if (!new) {
-		ipc_lock_by_ptr(&sma->sem_perm);
-		ipc_rcu_putref(sma);
-		sem_unlock(sma);
+		sem_putref(sma);
 		return ERR_PTR(-ENOMEM);
 	}
 	new->semadj = (short *) &new[1];
@@ -1062,13 +1017,10 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
 	if (un) {
 		spin_unlock(&ulp->lock);
 		kfree(new);
-		ipc_lock_by_ptr(&sma->sem_perm);
-		ipc_rcu_putref(sma);
-		sem_unlock(sma);
+		sem_putref(sma);
 		goto out;
 	}
-	ipc_lock_by_ptr(&sma->sem_perm);
-	ipc_rcu_putref(sma);
+	sem_lock_and_putref(sma);
 	if (sma->sem_perm.deleted) {
 		sem_unlock(sma);
 		spin_unlock(&ulp->lock);
@@ -1298,6 +1250,7 @@ void exit_sem(struct task_struct *tsk)
 	undo_list = tsk->sysvsem.undo_list;
 	if (!undo_list)
 		return;
+	tsk->sysvsem.undo_list = NULL;
 
 	if (!atomic_dec_and_test(&undo_list->refcnt))
 		return;
diff --git a/ipc/shm.c b/ipc/shm.c
index e636910454a..554429ade07 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -60,7 +60,6 @@ static struct vm_operations_struct shm_vm_ops;
 
 #define shm_unlock(shp)			\
 	ipc_unlock(&(shp)->shm_perm)
-#define shm_buildid(id, seq)	ipc_buildid(id, seq)
 
 static int newseg(struct ipc_namespace *, struct ipc_params *);
 static void shm_open(struct vm_area_struct *vma);
@@ -127,18 +126,6 @@ static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
 	return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
-static inline struct shmid_kernel *shm_lock_check_down(
-						struct ipc_namespace *ns,
-						int id)
-{
-	struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id);
-
-	if (IS_ERR(ipcp))
-		return (struct shmid_kernel *)ipcp;
-
-	return container_of(ipcp, struct shmid_kernel, shm_perm);
-}
-
 /*
  * shm_lock_(check_) routines are called in the paths where the rw_mutex
  * is not held.
@@ -169,12 +156,6 @@ static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 	ipc_rmid(&shm_ids(ns), &s->shm_perm);
 }
 
-static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
-{
-	return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
-}
-
-
 
 /* This is called by fork, once for every shm attach. */
 static void shm_open(struct vm_area_struct *vma)
@@ -416,7 +397,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	if (IS_ERR(file))
 		goto no_file;
 
-	id = shm_addid(ns, shp);
+	id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 	if (id < 0) {
 		error = id;
 		goto no_id;
@@ -428,7 +409,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	shp->shm_ctim = get_seconds();
 	shp->shm_segsz = size;
 	shp->shm_nattch = 0;
-	shp->shm_perm.id = shm_buildid(id, shp->shm_perm.seq);
 	shp->shm_file = file;
 	/*
 	 * shmid gets reported as "inode#" in /proc/pid/maps.
@@ -519,28 +499,14 @@ static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_
 	}
 }
 
-struct shm_setbuf {
-	uid_t	uid;
-	gid_t	gid;
-	mode_t	mode;
-};	
-
-static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
+static inline unsigned long
+copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 {
 	switch(version) {
 	case IPC_64:
-	    {
-		struct shmid64_ds tbuf;
-
-		if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
+		if (copy_from_user(out, buf, sizeof(*out)))
 			return -EFAULT;
-
-		out->uid	= tbuf.shm_perm.uid;
-		out->gid	= tbuf.shm_perm.gid;
-		out->mode	= tbuf.shm_perm.mode;
-
 		return 0;
-	    }
 	case IPC_OLD:
 	    {
 		struct shmid_ds tbuf_old;
@@ -548,9 +514,9 @@ static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __
 		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 			return -EFAULT;
 
-		out->uid	= tbuf_old.shm_perm.uid;
-		out->gid	= tbuf_old.shm_perm.gid;
-		out->mode	= tbuf_old.shm_perm.mode;
+		out->shm_perm.uid	= tbuf_old.shm_perm.uid;
+		out->shm_perm.gid	= tbuf_old.shm_perm.gid;
+		out->shm_perm.mode	= tbuf_old.shm_perm.mode;
 
 		return 0;
 	    }
@@ -624,9 +590,53 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 	}
 }
 
-asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
+/*
+ * This function handles some shmctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex is taken inside this function.
+ */
+static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
+		       struct shmid_ds __user *buf, int version)
+{
+	struct kern_ipc_perm *ipcp;
+	struct shmid64_ds shmid64;
+	struct shmid_kernel *shp;
+	int err;
+
+	if (cmd == IPC_SET) {
+		if (copy_shmid_from_user(&shmid64, buf, version))
+			return -EFAULT;
+	}
+
+	ipcp = ipcctl_pre_down(&shm_ids(ns), shmid, cmd, &shmid64.shm_perm, 0);
+	if (IS_ERR(ipcp))
+		return PTR_ERR(ipcp);
+
+	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
+
+	err = security_shm_shmctl(shp, cmd);
+	if (err)
+		goto out_unlock;
+	switch (cmd) {
+	case IPC_RMID:
+		do_shm_rmid(ns, ipcp);
+		goto out_up;
+	case IPC_SET:
+		ipc_update_perm(&shmid64.shm_perm, ipcp);
+		shp->shm_ctim = get_seconds();
+		break;
+	default:
+		err = -EINVAL;
+	}
+out_unlock:
+	shm_unlock(shp);
+out_up:
+	up_write(&shm_ids(ns).rw_mutex);
+	return err;
+}
+
+asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 {
-	struct shm_setbuf setbuf;
 	struct shmid_kernel *shp;
 	int err, version;
 	struct ipc_namespace *ns;
@@ -783,97 +793,13 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 		goto out;
 	}
 	case IPC_RMID:
-	{
-		/*
-		 *	We cannot simply remove the file. The SVID states
-		 *	that the block remains until the last person
-		 *	detaches from it, then is deleted. A shmat() on
-		 *	an RMID segment is legal in older Linux and if 
-		 *	we change it apps break...
-		 *
-		 *	Instead we set a destroyed flag, and then blow
-		 *	the name away when the usage hits zero.
-		 */
-		down_write(&shm_ids(ns).rw_mutex);
-		shp = shm_lock_check_down(ns, shmid);
-		if (IS_ERR(shp)) {
-			err = PTR_ERR(shp);
-			goto out_up;
-		}
-
-		err = audit_ipc_obj(&(shp->shm_perm));
-		if (err)
-			goto out_unlock_up;
-
-		if (current->euid != shp->shm_perm.uid &&
-		    current->euid != shp->shm_perm.cuid && 
-		    !capable(CAP_SYS_ADMIN)) {
-			err=-EPERM;
-			goto out_unlock_up;
-		}
-
-		err = security_shm_shmctl(shp, cmd);
-		if (err)
-			goto out_unlock_up;
-
-		do_shm_rmid(ns, &shp->shm_perm);
-		up_write(&shm_ids(ns).rw_mutex);
-		goto out;
-	}
-
 	case IPC_SET:
-	{
-		if (!buf) {
-			err = -EFAULT;
-			goto out;
-		}
-
-		if (copy_shmid_from_user (&setbuf, buf, version)) {
-			err = -EFAULT;
-			goto out;
-		}
-		down_write(&shm_ids(ns).rw_mutex);
-		shp = shm_lock_check_down(ns, shmid);
-		if (IS_ERR(shp)) {
-			err = PTR_ERR(shp);
-			goto out_up;
-		}
-		err = audit_ipc_obj(&(shp->shm_perm));
-		if (err)
-			goto out_unlock_up;
-		err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
-		if (err)
-			goto out_unlock_up;
-		err=-EPERM;
-		if (current->euid != shp->shm_perm.uid &&
-		    current->euid != shp->shm_perm.cuid && 
-		    !capable(CAP_SYS_ADMIN)) {
-			goto out_unlock_up;
-		}
-
-		err = security_shm_shmctl(shp, cmd);
-		if (err)
-			goto out_unlock_up;
-		
-		shp->shm_perm.uid = setbuf.uid;
-		shp->shm_perm.gid = setbuf.gid;
-		shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
-			| (setbuf.mode & S_IRWXUGO);
-		shp->shm_ctim = get_seconds();
-		break;
-	}
-
+		err = shmctl_down(ns, shmid, cmd, buf, version);
+		return err;
 	default:
-		err = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
-	err = 0;
-out_unlock_up:
-	shm_unlock(shp);
-out_up:
-	up_write(&shm_ids(ns).rw_mutex);
-	goto out;
 out_unlock:
 	shm_unlock(shp);
 out:
diff --git a/ipc/util.c b/ipc/util.c
index fd1b50da9db..3339177b336 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -33,6 +33,7 @@
 #include <linux/audit.h>
 #include <linux/nsproxy.h>
 #include <linux/rwsem.h>
+#include <linux/memory.h>
 #include <linux/ipc_namespace.h>
 
 #include <asm/unistd.h>
@@ -52,11 +53,57 @@ struct ipc_namespace init_ipc_ns = {
 	},
 };
 
+atomic_t nr_ipc_ns = ATOMIC_INIT(1);
+
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+
+static void ipc_memory_notifier(struct work_struct *work)
+{
+	ipcns_notify(IPCNS_MEMCHANGED);
+}
+
+static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
+
+
+static int ipc_memory_callback(struct notifier_block *self,
+				unsigned long action, void *arg)
+{
+	switch (action) {
+	case MEM_ONLINE:    /* memory successfully brought online */
+	case MEM_OFFLINE:   /* or offline: it's time to recompute msgmni */
+		/*
+		 * This is done by invoking the ipcns notifier chain with the
+		 * IPC_MEMCHANGED event.
+		 * In order not to keep the lock on the hotplug memory chain
+		 * for too long, queue a work item that will, when waken up,
+		 * activate the ipcns notification chain.
+		 * No need to keep several ipc work items on the queue.
+		 */
+		if (!work_pending(&ipc_memory_wq))
+			schedule_work(&ipc_memory_wq);
+		break;
+	case MEM_GOING_ONLINE:
+	case MEM_GOING_OFFLINE:
+	case MEM_CANCEL_ONLINE:
+	case MEM_CANCEL_OFFLINE:
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
 /**
  *	ipc_init	-	initialise IPC subsystem
  *
  *	The various system5 IPC resources (semaphores, messages and shared
  *	memory) are initialised
+ *	A callback routine is registered into the memory hotplug notifier
+ *	chain: since msgmni scales to lowmem this callback routine will be
+ *	called upon successful memory add / remove to recompute msmgni.
  */
  
 static int __init ipc_init(void)
@@ -64,6 +111,8 @@ static int __init ipc_init(void)
 	sem_init();
 	msg_init();
 	shm_init();
+	hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
+	register_ipcns_notifier(&init_ipc_ns);
 	return 0;
 }
 __initcall(ipc_init);
@@ -84,8 +133,8 @@ void ipc_init_ids(struct ipc_ids *ids)
 	ids->seq = 0;
 	{
 		int seq_limit = INT_MAX/SEQ_MULTIPLIER;
-		if(seq_limit > USHRT_MAX)
-			ids->seq_max = USHRT_MAX;
+		if (seq_limit > USHORT_MAX)
+			ids->seq_max = USHORT_MAX;
 		 else
 		 	ids->seq_max = seq_limit;
 	}
@@ -116,13 +165,12 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
 	iface->ids	= ids;
 	iface->show	= show;
 
-	pde = create_proc_entry(path,
-				S_IRUGO,        /* world readable */
-				NULL            /* parent dir */);
-	if (pde) {
-		pde->data = iface;
-		pde->proc_fops = &sysvipc_proc_fops;
-	} else {
+	pde = proc_create_data(path,
+			       S_IRUGO,        /* world readable */
+			       NULL,           /* parent dir */
+			       &sysvipc_proc_fops,
+			       iface);
+	if (!pde) {
 		kfree(iface);
 	}
 }
@@ -231,6 +279,7 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 	if(ids->seq > ids->seq_max)
 		ids->seq = 0;
 
+	new->id = ipc_buildid(id, new->seq);
 	spin_lock_init(&new->lock);
 	new->deleted = 0;
 	rcu_read_lock();
@@ -761,6 +810,70 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 		return ipcget_public(ns, ids, ops, params);
 }
 
+/**
+ * ipc_update_perm - update the permissions of an IPC.
+ * @in:  the permission given as input.
+ * @out: the permission of the ipc to set.
+ */
+void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
+{
+	out->uid = in->uid;
+	out->gid = in->gid;
+	out->mode = (out->mode & ~S_IRWXUGO)
+		| (in->mode & S_IRWXUGO);
+}
+
+/**
+ * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
+ * @ids:  the table of ids where to look for the ipc
+ * @id:   the id of the ipc to retrieve
+ * @cmd:  the cmd to check
+ * @perm: the permission to set
+ * @extra_perm: one extra permission parameter used by msq
+ *
+ * This function does some common audit and permissions check for some IPC_XXX
+ * cmd and is called from semctl_down, shmctl_down and msgctl_down.
+ * It must be called without any lock held and
+ *  - retrieves the ipc with the given id in the given table.
+ *  - performs some audit and permission check, depending on the given cmd
+ *  - returns the ipc with both ipc and rw_mutex locks held in case of success
+ *    or an err-code without any lock held otherwise.
+ */
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+				      struct ipc64_perm *perm, int extra_perm)
+{
+	struct kern_ipc_perm *ipcp;
+	int err;
+
+	down_write(&ids->rw_mutex);
+	ipcp = ipc_lock_check_down(ids, id);
+	if (IS_ERR(ipcp)) {
+		err = PTR_ERR(ipcp);
+		goto out_up;
+	}
+
+	err = audit_ipc_obj(ipcp);
+	if (err)
+		goto out_unlock;
+
+	if (cmd == IPC_SET) {
+		err = audit_ipc_set_perm(extra_perm, perm->uid,
+					 perm->gid, perm->mode);
+		if (err)
+			goto out_unlock;
+	}
+	if (current->euid == ipcp->cuid ||
+	    current->euid == ipcp->uid || capable(CAP_SYS_ADMIN))
+		return ipcp;
+
+	err = -EPERM;
+out_unlock:
+	ipc_unlock(ipcp);
+out_up:
+	up_write(&ids->rw_mutex);
+	return ERR_PTR(err);
+}
+
 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
 
 
diff --git a/ipc/util.h b/ipc/util.h
index f37d160c98f..cdb966aebe0 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -12,7 +12,6 @@
 
 #include <linux/err.h>
 
-#define USHRT_MAX 0xffff
 #define SEQ_MULTIPLIER	(IPCMNI)
 
 void sem_init (void);
@@ -112,6 +111,9 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
+void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
+struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
+				      struct ipc64_perm *perm, int extra_perm);
 
 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */ 
@@ -124,6 +126,8 @@ extern void free_msg(struct msg_msg *msg);
 extern struct msg_msg *load_msg(const void __user *src, int len);
 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 
+extern void recompute_msgmni(struct ipc_namespace *);
+
 static inline int ipc_buildid(int id, int seq)
 {
 	return SEQ_MULTIPLIER * seq + id;