cregit-Linux how code gets into the kernel

Release 4.17 ipc/msg.c

Directory: ipc
// SPDX-License-Identifier: GPL-2.0
/*
 * 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 msq_queue structure for each present queue on the system */

struct msg_queue {
	
struct kern_ipc_perm q_perm;
	
time64_t q_stime;		/* last msgsnd time */
	
time64_t q_rtime;		/* last msgrcv time */
	
time64_t q_ctime;		/* last change time */
	
unsigned long q_cbytes;		/* current number of bytes on queue */
	
unsigned long q_qnum;		/* number of messages in queue */
	
unsigned long q_qbytes;		/* max number of bytes on queue */
	
struct pid *q_lspid;		/* pid of last msgsnd */
	
struct pid *q_lrpid;		/* last receive pid */

	
struct list_head q_messages;
	
struct list_head q_receivers;
	
struct list_head q_senders;

} __randomize_layout;

/* 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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Davidlohr Bueso A57100.00%2100.00%
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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Davidlohr Bueso A57100.00%1100.00%
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->q_perm); kvfree(msq); }

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PersonTokensPropCommitsCommitProp
Davidlohr Bueso A3768.52%120.00%
Manfred Spraul814.81%120.00%
Kees Cook611.11%240.00%
Eric W. Biedermann35.56%120.00%
Total54100.00%5100.00%

/** * 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->q_perm); if (retval) { kvfree(msq); return retval; } msq->q_stime = msq->q_rtime = 0; msq->q_ctime = ktime_get_real_seconds(); msq->q_cbytes = msq->q_qnum = 0; msq->q_qbytes = ns->msg_ctlmnb; msq->q_lspid = msq->q_lrpid = NULL; 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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PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)9538.93%417.39%
Linus Torvalds3514.34%14.35%
Greg Kroah-Hartman239.43%313.04%
Stephen D. Smalley239.43%14.35%
Nadia Derbey218.61%28.70%
Kees Cook145.74%14.35%
Manfred Spraul93.69%28.70%
Davidlohr Bueso A72.87%28.70%
Kirill Korotaev72.87%14.35%
Eric W. Biedermann41.64%28.70%
Ingo Molnar31.23%14.35%
Andrew Morton10.41%14.35%
Andi Kleen10.41%14.35%
Deepa Dinamani10.41%14.35%
Total244100.00%23100.00%


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); }

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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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PersonTokensPropCommitsCommitProp
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

PersonTokensPropCommitsCommitProp
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_update_pid(&msq->q_lspid, NULL); ipc_update_pid(&msq->q_lrpid, NULL); ipc_rcu_putref(&msq->q_perm, msg_rcu_free); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)5736.54%418.18%
Pierre Peiffer1710.90%14.55%
Davidlohr Bueso A138.33%418.18%
Sebastian Andrzej Siewior138.33%14.55%
Nikola Pajkovsky127.69%14.55%
Kirill Korotaev117.05%29.09%
Eric W. Biedermann106.41%14.55%
Nadia Derbey95.77%313.64%
Andrew Morton74.49%29.09%
Manfred Spraul63.85%29.09%
Waiman Long10.64%14.55%
Total156100.00%22100.00%


long ksys_msgget(key_t key, int msgflg) { struct ipc_namespace *ns; static const struct ipc_ops msg_ops = { .getnew = newque, .associate = security_msg_queue_associate, }; 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); }

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PersonTokensPropCommitsCommitProp
Nadia Derbey2228.95%110.00%
Mathias Krause1317.11%110.00%
Linus Torvalds (pre-git)1317.11%330.00%
Kirill Korotaev1317.11%110.00%
Dominik Brodowski911.84%110.00%
Ingo Molnar33.95%110.00%
Stephen D. Smalley22.63%110.00%
Eric W. Biedermann11.32%110.00%
Total76100.00%10100.00%

SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) { return ksys_msgget(key, msgflg); }
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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PersonTokensPropCommitsCommitProp
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 msqid64_ds *msqid64) { struct kern_ipc_perm *ipcp; struct msg_queue *msq; int err; 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->q_perm, 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 = ktime_get_real_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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PersonTokensPropCommitsCommitProp
Pierre Peiffer12740.84%417.39%
Davidlohr Bueso A8627.65%521.74%
Linus Torvalds (pre-git)4113.18%417.39%
Eric W. Biedermann175.47%28.70%
Nadia Derbey144.50%14.35%
Ingo Molnar72.25%14.35%
Al Viro72.25%14.35%
Kirill Korotaev51.61%14.35%
Sebastian Andrzej Siewior30.96%14.35%
Serge E. Hallyn20.64%14.35%
Deepa Dinamani10.32%14.35%
Waiman Long10.32%14.35%
Total311100.00%23100.00%


static int msgctl_info(struct ipc_namespace *ns, int msqid, int cmd, struct msginfo *msginfo) { int err; 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); return (max_id < 0) ? 0 : max_id; }

Contributors

PersonTokensPropCommitsCommitProp
Pierre Peiffer12059.41%112.50%
Linus Torvalds (pre-git)2813.86%225.00%
Al Viro178.42%112.50%
Davidlohr Bueso A157.43%225.00%
Stephen D. Smalley125.94%112.50%
Nadia Derbey104.95%112.50%
Total202100.00%8100.00%


static int msgctl_stat(struct ipc_namespace *ns, int msqid, int cmd, struct msqid64_ds *p) { struct msg_queue *msq; int id = 0; int err; memset(p, 0, sizeof(*p)); rcu_read_lock(); if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) { msq = msq_obtain_object(ns, msqid); if (IS_ERR(msq)) { err = PTR_ERR(msq); goto out_unlock; } id = msq->q_perm.id; } else { /* IPC_STAT */ msq = msq_obtain_object_check(ns, msqid); if (IS_ERR(msq)) { err = PTR_ERR(msq); goto out_unlock; } } /* see comment for SHM_STAT_ANY */ if (cmd == MSG_STAT_ANY) audit_ipc_obj(&msq->q_perm); else { err = -EACCES; if (ipcperms(ns, &msq->q_perm, S_IRUGO)) goto out_unlock; } err = security_msg_queue_msgctl(&msq->q_perm, cmd); if (err) goto out_unlock; ipc_lock_object(&msq->q_perm); if (!ipc_valid_object(&msq->q_perm)) { ipc_unlock_object(&msq->q_perm); err = -EIDRM; 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 = pid_vnr(msq->q_lspid); p->msg_lrpid = pid_vnr(msq->q_lrpid); ipc_unlock_object(&msq->q_perm); rcu_read_unlock(); return id; out_unlock: rcu_read_unlock(); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Pierre Peiffer7723.19%15.88%
Davidlohr Bueso A6519.58%317.65%
Philippe Mikoyan5315.96%15.88%
Linus Torvalds (pre-git)5015.06%317.65%
Al Viro4413.25%15.88%
Stephen D. Smalley154.52%15.88%
Eric W. Biedermann92.71%211.76%
Steve Grubb72.11%15.88%
Nadia Derbey41.20%15.88%
Linda Knippers41.20%15.88%
Kirill Korotaev20.60%15.88%
Serge E. Hallyn20.60%15.88%
Total332100.00%17100.00%


long ksys_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; version = ipc_parse_version(&cmd); ns = current->nsproxy->ipc_ns; switch (cmd) { case IPC_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 MSG_STAT_ANY: case IPC_STAT: 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, &msqid64); default: return -EINVAL; } }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro10547.51%112.50%
Davidlohr Bueso A7835.29%225.00%
Pierre Peiffer188.14%112.50%
Dominik Brodowski156.79%112.50%
Linus Torvalds (pre-git)31.36%225.00%
Kirill Korotaev20.90%112.50%
Total221100.00%8100.00%

SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) { return ksys_msgctl(msqid, cmd, buf); } #ifdef CONFIG_COMPAT struct compat_msqid_ds { struct compat_ipc_perm msg_perm; compat_uptr_t msg_first; compat_uptr_t msg_last; compat_time_t msg_stime; compat_time_t msg_rtime; compat_time_t msg_ctime; compat_ulong_t msg_lcbytes; compat_ulong_t msg_lqbytes; unsigned short msg_cbytes; unsigned short msg_qnum; unsigned short msg_qbytes; compat_ipc_pid_t msg_lspid; compat_ipc_pid_t msg_lrpid; };
static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) { memset(out, 0, sizeof(*out)); if (version == IPC_64) { struct compat_msqid64_ds __user *p = buf; if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm)) return -EFAULT; if (get_user(out->msg_qbytes, &p->msg_qbytes)) return -EFAULT; } else { struct compat_msqid_ds __user *p = buf