cregit-Linux how code gets into the kernel

Release 4.13 ipc/msg.c

Directory: ipc
/*
 * linux/ipc/msg.c
 * Copyright (C) 1992 Krishna Balasubramanian
 *
 * Removed all the remaining kerneld mess
 * Catch the -EFAULT stuff properly
 * Use GFP_KERNEL for messages as in 1.2
 * Fixed up the unchecked user space derefs
 * Copyright (C) 1998 Alan Cox & Andi Kleen
 *
 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
 *
 * mostly rewritten, threaded and wake-one semantics added
 * MSGMAX limit removed, sysctl's added
 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
 *
 * support for audit of ipc object properties and permission changes
 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
 *
 * namespaces support
 * OpenVZ, SWsoft Inc.
 * Pavel Emelianov <xemul@openvz.org>
 */

#include <linux/capability.h>
#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>
#include <linux/sched/wake_q.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/seq_file.h>
#include <linux/rwsem.h>
#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>

#include <asm/current.h>
#include <linux/uaccess.h>
#include "util.h"

/* one msg_receiver structure for each sleeping receiver */

struct msg_receiver {
	
struct list_head	r_list;
	
struct task_struct	*r_tsk;

	
int			r_mode;
	
long			r_msgtype;
	
long			r_maxsize;

	
struct msg_msg		*r_msg;
};

/* one msg_sender for each sleeping sender */

struct msg_sender {
	
struct list_head	list;
	
struct task_struct	*tsk;
	
size_t                  msgsz;
};


#define SEARCH_ANY		1

#define SEARCH_EQUAL		2

#define SEARCH_NOTEQUAL		3

#define SEARCH_LESSEQUAL	4

#define SEARCH_NUMBER		5


#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])




static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
{
	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);

	if (IS_ERR(ipcp))
		return ERR_CAST(ipcp);

	return container_of(ipcp, struct msg_queue, q_perm);
}


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Total57100.00%2100.00%






static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
							int id)
{
	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);

	if (IS_ERR(ipcp))
		return ERR_CAST(ipcp);

	return container_of(ipcp, struct msg_queue, q_perm);
}


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Total57100.00%1100.00%






static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
{
	ipc_rmid(&msg_ids(ns), &s->q_perm);
}


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Nadia Derbey31100.00%1100.00%


Total31100.00%1100.00%






static void msg_rcu_free(struct rcu_head *head)
{
	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
	struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);

	security_msg_queue_free(msq);
	kvfree(msq);
}


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Davidlohr Bueso A3772.55%125.00%


Manfred Spraul815.69%125.00%


Kees Cook611.76%250.00%


Total51100.00%4100.00%



/**
 * newque - Create a new msg queue
 * @ns: namespace
 * @params: ptr to the structure that contains the key and msgflg
 *
 * Called with msg_ids.rwsem held (writer)
 */



static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
	struct msg_queue *msq;
	int retval;
	key_t key = params->key;
	int msgflg = params->flg;

	msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
	if (unlikely(!msq))
		return -ENOMEM;

	msq->q_perm.mode = msgflg & S_IRWXUGO;
	msq->q_perm.key = key;

	msq->q_perm.security = NULL;
	retval = security_msg_queue_alloc(msq);
	if (retval) {
		kvfree(msq);
		return retval;
	}

	msq->q_stime = msq->q_rtime = 0;
	msq->q_ctime = get_seconds();
	msq->q_cbytes = msq->q_qnum = 0;
	msq->q_qbytes = ns->msg_ctlmnb;
	msq->q_lspid = msq->q_lrpid = 0;
	INIT_LIST_HEAD(&msq->q_messages);
	INIT_LIST_HEAD(&msq->q_receivers);
	INIT_LIST_HEAD(&msq->q_senders);

	/* ipc_addid() locks msq upon success. */
	retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
	if (retval < 0) {
		call_rcu(&msq->q_perm.rcu, msg_rcu_free);
		return retval;
	}

	ipc_unlock_object(&msq->q_perm);
	rcu_read_unlock();

	return msq->q_perm.id;
}


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Linus Torvalds (pre-git)9639.83%420.00%


Linus Torvalds3514.52%15.00%


Greg Kroah-Hartman239.54%315.00%


Stephen D. Smalley239.54%15.00%


Nadia Derbey218.71%210.00%


Kees Cook145.81%15.00%


Manfred Spraul93.73%210.00%


Kirill Korotaev72.90%15.00%


Davidlohr Bueso A72.90%210.00%


Ingo Molnar31.24%15.00%


Andi Kleen20.83%15.00%


Andrew Morton10.41%15.00%


Total241100.00%20100.00%






static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
{
	return msgsz + msq->q_cbytes <= msq->q_qbytes &&
		1 + msq->q_qnum <= msq->q_qbytes;
}


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Davidlohr Bueso A36100.00%1100.00%


Total36100.00%1100.00%






static inline void ss_add(struct msg_queue *msq,
			  struct msg_sender *mss, size_t msgsz)
{
	mss->tsk = current;
	mss->msgsz = msgsz;
	__set_current_state(TASK_INTERRUPTIBLE);
	list_add_tail(&mss->list, &msq->q_senders);
}


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Linus Torvalds (pre-git)3876.00%133.33%


Davidlohr Bueso A1224.00%266.67%


Total50100.00%3100.00%






static inline void ss_del(struct msg_sender *mss)
{
	if (mss->list.next)
		list_del(&mss->list);
}


Contributors
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Linus Torvalds (pre-git)28100.00%1100.00%


Total28100.00%1100.00%






static void ss_wakeup(struct msg_queue *msq,
		      struct wake_q_head *wake_q, bool kill)
{
	struct msg_sender *mss, *t;
	struct task_struct *stop_tsk = NULL;
	struct list_head *h = &msq->q_senders;

	list_for_each_entry_safe(mss, t, h, list) {
		if (kill)
			mss->list.next = NULL;

		/*
                 * Stop at the first task we don't wakeup,
                 * we've already iterated the original
                 * sender queue.
                 */
		else if (stop_tsk == mss->tsk)
			break;
		/*
                 * We are not in an EIDRM scenario here, therefore
                 * verify that we really need to wakeup the task.
                 * To maintain current semantics and wakeup order,
                 * move the sender to the tail on behalf of the
                 * blocked task.
                 */
		else if (!msg_fits_inqueue(msq, mss->msgsz)) {
			if (!stop_tsk)
				stop_tsk = mss->tsk;

			list_move_tail(&mss->list, &msq->q_senders);
			continue;
		}

		wake_q_add(wake_q, mss->tsk);
	}
}


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Davidlohr Bueso A8062.02%342.86%


Linus Torvalds (pre-git)3930.23%342.86%


Nikola Pajkovsky107.75%114.29%


Total129100.00%7100.00%






static void expunge_all(struct msg_queue *msq, int res,
			struct wake_q_head *wake_q)
{
	struct msg_receiver *msr, *t;

	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
		wake_q_add(wake_q, msr->r_tsk);
		WRITE_ONCE(msr->r_msg, ERR_PTR(res));
	}
}


Contributors
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Linus Torvalds (pre-git)3050.00%350.00%


Sebastian Andrzej Siewior1220.00%116.67%


Nikola Pajkovsky1016.67%116.67%


Manfred Spraul813.33%116.67%


Total60100.00%6100.00%



/*
 * freeque() wakes up waiters on the sender and receiver waiting queue,
 * removes the message queue from message queue ID IDR, and cleans up all the
 * messages associated with this queue.
 *
 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
 * before freeque() is called. msg_ids.rwsem remains locked on exit.
 */



static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
{
	struct msg_msg *msg, *t;
	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
	DEFINE_WAKE_Q(wake_q);

	expunge_all(msq, -EIDRM, &wake_q);
	ss_wakeup(msq, &wake_q, true);
	msg_rmid(ns, msq);
	ipc_unlock_object(&msq->q_perm);
	wake_up_q(&wake_q);
	rcu_read_unlock();

	list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
		atomic_dec(&ns->msg_hdrs);
		free_msg(msg);
	}
	atomic_sub(msq->q_cbytes, &ns->msg_bytes);
	ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
}


Contributors
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Linus Torvalds (pre-git)5741.91%421.05%


Pierre Peiffer1712.50%15.26%


Davidlohr Bueso A139.56%421.05%


Sebastian Andrzej Siewior139.56%15.26%


Nikola Pajkovsky128.82%15.26%


Kirill Korotaev118.09%210.53%


Andrew Morton75.15%210.53%


Manfred Spraul42.94%210.53%


Waiman Long10.74%15.26%


Nadia Derbey10.74%15.26%


Total136100.00%19100.00%



/*
 * Called with msg_ids.rwsem and ipcp locked.
 */



static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
{
	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);

	return security_msg_queue_associate(msq, msgflg);
}


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Nadia Derbey38100.00%2100.00%


Total38100.00%2100.00%




SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
{
	struct ipc_namespace *ns;
	static const struct ipc_ops msg_ops = {
		.getnew = newque,
		.associate = msg_security,
        };
	struct ipc_params msg_params;

	ns = current->nsproxy->ipc_ns;

	msg_params.key = key;
	msg_params.flg = msgflg;

	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
}



static inline unsigned long

copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
	switch (version) {
	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	{
		struct msqid_ds out;

		memset(&out, 0, sizeof(out));

		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);

		out.msg_stime		= in->msg_stime;
		out.msg_rtime		= in->msg_rtime;
		out.msg_ctime		= in->msg_ctime;

		if (in->msg_cbytes > USHRT_MAX)
			out.msg_cbytes	= USHRT_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;
		else
			out.msg_qnum	= in->msg_qnum;

		if (in->msg_qbytes > USHRT_MAX)
			out.msg_qbytes	= USHRT_MAX;
		else
			out.msg_qbytes	= in->msg_qbytes;
		out.msg_lqbytes		= in->msg_qbytes;

		out.msg_lspid		= in->msg_lspid;
		out.msg_lrpid		= in->msg_lrpid;

		return copy_to_user(buf, &out, sizeof(out));
	}
	default:
		return -EINVAL;
	}
}


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Linus Torvalds (pre-git)21696.86%133.33%


Alexey Dobriyan62.69%133.33%


Al Viro10.45%133.33%


Total223100.00%3100.00%





static inline unsigned long

copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
{
	switch (version) {
	case IPC_64:
		if (copy_from_user(out, buf, sizeof(*out)))
			return -EFAULT;
		return 0;
	case IPC_OLD:
	{
		struct msqid_ds tbuf_old;

		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
			return -EFAULT;

		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->msg_qbytes	= tbuf_old.msg_lqbytes;
		else
			out->msg_qbytes	= tbuf_old.msg_qbytes;

		return 0;
	}
	default:
		return -EINVAL;
	}
}


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Linus Torvalds (pre-git)13691.28%133.33%


Pierre Peiffer128.05%133.33%


Al Viro10.67%133.33%


Total149100.00%3100.00%



/*
 * This function handles some msgctl commands which require the rwsem
 * to be held in write mode.
 * 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 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);
	if (IS_ERR(ipcp)) {
		err = PTR_ERR(ipcp);
		goto out_unlock1;
	}

	msq = container_of(ipcp, struct msg_queue, q_perm);

	err = security_msg_queue_msgctl(msq, cmd);
	if (err)
		goto out_unlock1;

	switch (cmd) {
	case IPC_RMID:
		ipc_lock_object(&msq->q_perm);
		/* freeque unlocks the ipc object and rcu */
		freeque(ns, ipcp);
		goto out_up;
	case IPC_SET:
	{
		DEFINE_WAKE_Q(wake_q);

		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);
		if (err)
			goto out_unlock0;

		msq->q_qbytes = msqid64.msg_qbytes;

		msq->q_ctime = get_seconds();
		/*
                 * Sleeping receivers might be excluded by
                 * stricter permissions.
                 */
		expunge_all(msq, -EAGAIN, &wake_q);
		/*
                 * Sleeping senders might be able to send
                 * due to a larger queue size.
                 */
		ss_wakeup(msq, &wake_q, false);
		ipc_unlock_object(&msq->q_perm);
		wake_up_q(&wake_q);

		goto out_unlock1;
	}
	default:
		err = -EINVAL;
		goto out_unlock1;
	}

out_unlock0:
	ipc_unlock_object(&msq->q_perm);
out_unlock1:
	rcu_read_unlock();
out_up:
	up_write(&msg_ids(ns).rwsem);
	return err;
}


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Pierre Peiffer14843.15%417.39%


Davidlohr Bueso A8625.07%521.74%


Linus Torvalds (pre-git)5215.16%417.39%


Eric W. Biedermann154.37%14.35%


Nadia Derbey144.08%14.35%


Ingo Molnar72.04%14.35%


Stephen D. Smalley61.75%14.35%


Kirill Korotaev51.46%14.35%


Felipe Contreras30.87%14.35%


Sebastian Andrzej Siewior30.87%14.35%


Serge E. Hallyn20.58%14.35%


Waiman Long10.29%14.35%


Al Viro10.29%14.35%


Total343100.00%23100.00%






static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
			 int cmd, int version, void __user *buf)
{
	int err;
	struct msg_queue *msq;

	switch (cmd) {
	case IPC_INFO:
	case MSG_INFO:
	{
		struct msginfo msginfo;
		int max_id;

		if (!buf)
			return -EFAULT;

		/*
                 * 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;
	}

	case MSG_STAT:
	case IPC_STAT:
	{
		struct msqid64_ds tbuf;
		int success_return;

		if (!buf)
			return -EFAULT;

		memset(&tbuf, 0, sizeof(tbuf));

		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;
		}

		err = -EACCES;
		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
			goto out_unlock;

		err = security_msg_queue_msgctl(msq, cmd);
		if (err)
			goto out_unlock;

		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();

		if (copy_msqid_to_user(buf, &tbuf, version))
			return -EFAULT;
		return success_return;
	}

	default:
		return -EINVAL;
	}

	return err;
out_unlock:
	rcu_read_unlock();
	return err;
}


Contributors
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Pierre Peiffer27551.98%213.33%


Linus Torvalds (pre-git)11521.74%426.67%


Davidlohr Bueso A8015.12%320.00%


Stephen D. Smalley275.10%16.67%


Nadia Derbey152.84%16.67%


Steve Grubb71.32%16.67%


Linda Knippers50.95%16.67%


Kirill Korotaev30.57%16.67%


Serge E. Hallyn20.38%16.67%


Total529100.00%15100.00%




SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
{
	int version;
	struct ipc_namespace *ns;

	if (msqid < 0 || cmd < 0)
		return -EINVAL;

	version = ipc_parse_version(&cmd);
	ns = current->nsproxy->ipc_ns;

	switch (cmd) {
	case IPC_INFO:
	case MSG_INFO:
	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
	case IPC_STAT:
		return msgctl_nolock(ns, msqid, cmd, version, buf);
	case IPC_SET:
	case IPC_RMID:
		return msgctl_down(ns, msqid, cmd, buf, version);
	default:
		return  -EINVAL;
	}
}




static int testmsg(struct msg_msg *msg, long type, int mode)
{
	switch (mode) {
	case SEARCH_ANY:
	case SEARCH_NUMBER:
		return 1;
	case SEARCH_LESSEQUAL:
		if (msg->m_type <= type)
			return 1;
		break;
	case SEARCH_EQUAL:
		if (msg->m_type == type)
			return 1;
		break;
	case SEARCH_NOTEQUAL:
		if (msg->m_type != type)
			return 1;
		break;
	}
	return 0;
}


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Linus Torvalds (pre-git)7796.25%375.00%


Peter Hurley33.75%125.00%


Total80100.00%4100.00%






static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
				 struct wake_q_head *wake_q)
{
	struct msg_receiver *msr, *t;

	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
		    !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
					       msr->r_msgtype, msr->r_mode)) {

			list_del(&msr->r_list);
			if (msr->r_maxsize < msg->m_ts) {
				wake_q_add(wake_q, msr->r_tsk);
				WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
			} else {
				msq->q_lrpid = task_pid_vnr(msr->r_tsk);
				msq->q_rtime = get_seconds();

				wake_q_add(wake_q, msr->r_tsk);
				WRITE_ONCE(msr->r_msg, msg);
				return 1;
			}
		}
	}

	return 0;
}


Contributors
PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)9557.23%325.00%


Stephen D. Smalley2012.05%18.33%


Sebastian Andrzej Siewior1911.45%18.33%


Manfred Spraul148.43%18.33%


Nikola Pajkovsky106.02%18.33%


Pavel Emelyanov31.81%18.33%


Andi Kleen21.20%18.33%


Stephen Rothwell10.60%18.33%


Dave Jones10.60%18.33%


Linus Torvalds10.60%18.33%


Total166100.00%12100.00%






long do_msgsnd(int msqid, long mtype, void __user *mtext,
		size_t msgsz, int msgflg)
{
	struct msg_queue *msq;
	struct msg_msg *msg;
	int err;
	struct ipc_namespace *ns;
	DEFINE_WAKE_Q(wake_q);

	ns = current->nsproxy->ipc_ns;

	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
		return -EINVAL;
	if (mtype < 1)
		return -EINVAL;

	msg = load_msg(mtext, msgsz);
	if (IS_ERR(msg))
		return PTR_ERR(msg);

	msg->m_type = mtype;
	msg->m_ts =