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![Fabian Frederick](/assets/img/avatar_default.png)
Commit53dad6d3a8
("ipc: fix race with LSMs") updated ipc_rcu_putref() to receive rcu freeing function but used generic ipc_rcu_free() instead of msg_rcu_free() which does security cleaning. Running LTP msgsnd06 with kmemleak gives the following: cat /sys/kernel/debug/kmemleak unreferenced object 0xffff88003c0a11f8 (size 8): comm "msgsnd06", pid 1645, jiffies 4294672526 (age 6.549s) hex dump (first 8 bytes): 1b 00 00 00 01 00 00 00 ........ backtrace: kmemleak_alloc+0x23/0x40 kmem_cache_alloc_trace+0xe1/0x180 selinux_msg_queue_alloc_security+0x3f/0xd0 security_msg_queue_alloc+0x2e/0x40 newque+0x4e/0x150 ipcget+0x159/0x1b0 SyS_msgget+0x39/0x40 entry_SYSCALL_64_fastpath+0x13/0x8f Manfred Spraul suggested to fix sem.c as well and Davidlohr Bueso to only use ipc_rcu_free in case of security allocation failure in newary() Fixes:53dad6d3a8
("ipc: fix race with LSMs") Link: http://lkml.kernel.org/r/1470083552-22966-1-git-send-email-fabf@skynet.be Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: <stable@vger.kernel.org> [3.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1074 lines
24 KiB
C
1074 lines
24 KiB
C
/*
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* linux/ipc/msg.c
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* Copyright (C) 1992 Krishna Balasubramanian
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*
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* Removed all the remaining kerneld mess
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* Catch the -EFAULT stuff properly
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* Use GFP_KERNEL for messages as in 1.2
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* Fixed up the unchecked user space derefs
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* Copyright (C) 1998 Alan Cox & Andi Kleen
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*
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* /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
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*
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* mostly rewritten, threaded and wake-one semantics added
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* MSGMAX limit removed, sysctl's added
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* (c) 1999 Manfred Spraul <manfred@colorfullife.com>
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*
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* support for audit of ipc object properties and permission changes
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* Dustin Kirkland <dustin.kirkland@us.ibm.com>
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*
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* namespaces support
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* OpenVZ, SWsoft Inc.
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* Pavel Emelianov <xemul@openvz.org>
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*/
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#include <linux/capability.h>
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#include <linux/msg.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/proc_fs.h>
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#include <linux/list.h>
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#include <linux/security.h>
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <linux/audit.h>
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#include <linux/seq_file.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <linux/ipc_namespace.h>
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#include <asm/current.h>
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#include <linux/uaccess.h>
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#include "util.h"
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/* one msg_receiver structure for each sleeping receiver */
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struct msg_receiver {
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struct list_head r_list;
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struct task_struct *r_tsk;
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int r_mode;
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long r_msgtype;
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long r_maxsize;
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/*
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* Mark r_msg volatile so that the compiler
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* does not try to get smart and optimize
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* it. We rely on this for the lockless
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* receive algorithm.
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*/
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struct msg_msg *volatile r_msg;
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};
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/* one msg_sender for each sleeping sender */
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struct msg_sender {
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struct list_head list;
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struct task_struct *tsk;
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};
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#define SEARCH_ANY 1
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#define SEARCH_EQUAL 2
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#define SEARCH_NOTEQUAL 3
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#define SEARCH_LESSEQUAL 4
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#define SEARCH_NUMBER 5
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#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
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static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
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{
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struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
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if (IS_ERR(ipcp))
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return ERR_CAST(ipcp);
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return container_of(ipcp, struct msg_queue, q_perm);
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}
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static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
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if (IS_ERR(ipcp))
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return ERR_CAST(ipcp);
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return container_of(ipcp, struct msg_queue, q_perm);
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}
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static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
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{
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ipc_rmid(&msg_ids(ns), &s->q_perm);
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}
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static void msg_rcu_free(struct rcu_head *head)
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{
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struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
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struct msg_queue *msq = ipc_rcu_to_struct(p);
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security_msg_queue_free(msq);
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ipc_rcu_free(head);
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}
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/**
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* newque - Create a new msg queue
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* @ns: namespace
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* @params: ptr to the structure that contains the key and msgflg
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*
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* Called with msg_ids.rwsem held (writer)
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*/
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static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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{
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struct msg_queue *msq;
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int id, retval;
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key_t key = params->key;
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int msgflg = params->flg;
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msq = ipc_rcu_alloc(sizeof(*msq));
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if (!msq)
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return -ENOMEM;
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msq->q_perm.mode = msgflg & S_IRWXUGO;
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msq->q_perm.key = key;
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msq->q_perm.security = NULL;
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retval = security_msg_queue_alloc(msq);
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if (retval) {
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ipc_rcu_putref(msq, ipc_rcu_free);
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return retval;
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}
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msq->q_stime = msq->q_rtime = 0;
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msq->q_ctime = get_seconds();
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msq->q_cbytes = msq->q_qnum = 0;
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msq->q_qbytes = ns->msg_ctlmnb;
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msq->q_lspid = msq->q_lrpid = 0;
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INIT_LIST_HEAD(&msq->q_messages);
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INIT_LIST_HEAD(&msq->q_receivers);
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INIT_LIST_HEAD(&msq->q_senders);
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/* ipc_addid() locks msq upon success. */
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id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
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if (id < 0) {
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ipc_rcu_putref(msq, msg_rcu_free);
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return id;
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}
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ipc_unlock_object(&msq->q_perm);
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rcu_read_unlock();
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return msq->q_perm.id;
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}
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static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
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{
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mss->tsk = current;
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__set_current_state(TASK_INTERRUPTIBLE);
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list_add_tail(&mss->list, &msq->q_senders);
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}
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static inline void ss_del(struct msg_sender *mss)
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{
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if (mss->list.next != NULL)
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list_del(&mss->list);
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}
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static void ss_wakeup(struct list_head *h, int kill)
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{
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struct msg_sender *mss, *t;
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list_for_each_entry_safe(mss, t, h, list) {
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if (kill)
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mss->list.next = NULL;
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wake_up_process(mss->tsk);
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}
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}
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static void expunge_all(struct msg_queue *msq, int res)
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{
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struct msg_receiver *msr, *t;
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list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
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msr->r_msg = NULL; /* initialize expunge ordering */
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wake_up_process(msr->r_tsk);
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/*
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* Ensure that the wakeup is visible before setting r_msg as
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* the receiving end depends on it: either spinning on a nil,
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* or dealing with -EAGAIN cases. See lockless receive part 1
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* and 2 in do_msgrcv().
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*/
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smp_wmb(); /* barrier (B) */
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msr->r_msg = ERR_PTR(res);
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}
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}
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/*
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* freeque() wakes up waiters on the sender and receiver waiting queue,
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* removes the message queue from message queue ID IDR, and cleans up all the
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* messages associated with this queue.
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*
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* msg_ids.rwsem (writer) and the spinlock for this message queue are held
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* before freeque() is called. msg_ids.rwsem remains locked on exit.
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*/
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static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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{
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struct msg_msg *msg, *t;
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struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
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expunge_all(msq, -EIDRM);
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ss_wakeup(&msq->q_senders, 1);
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msg_rmid(ns, msq);
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ipc_unlock_object(&msq->q_perm);
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rcu_read_unlock();
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list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
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atomic_dec(&ns->msg_hdrs);
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free_msg(msg);
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}
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atomic_sub(msq->q_cbytes, &ns->msg_bytes);
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ipc_rcu_putref(msq, msg_rcu_free);
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}
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/*
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* Called with msg_ids.rwsem and ipcp locked.
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*/
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static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
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{
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struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
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return security_msg_queue_associate(msq, msgflg);
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}
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SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
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{
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struct ipc_namespace *ns;
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static const struct ipc_ops msg_ops = {
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.getnew = newque,
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.associate = msg_security,
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};
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struct ipc_params msg_params;
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ns = current->nsproxy->ipc_ns;
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msg_params.key = key;
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msg_params.flg = msgflg;
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return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
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}
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static inline unsigned long
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copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
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{
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switch (version) {
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case IPC_64:
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return copy_to_user(buf, in, sizeof(*in));
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case IPC_OLD:
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{
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struct msqid_ds out;
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memset(&out, 0, sizeof(out));
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ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
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out.msg_stime = in->msg_stime;
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out.msg_rtime = in->msg_rtime;
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out.msg_ctime = in->msg_ctime;
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if (in->msg_cbytes > USHRT_MAX)
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out.msg_cbytes = USHRT_MAX;
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else
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out.msg_cbytes = in->msg_cbytes;
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out.msg_lcbytes = in->msg_cbytes;
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if (in->msg_qnum > USHRT_MAX)
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out.msg_qnum = USHRT_MAX;
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else
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out.msg_qnum = in->msg_qnum;
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if (in->msg_qbytes > USHRT_MAX)
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out.msg_qbytes = USHRT_MAX;
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else
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out.msg_qbytes = in->msg_qbytes;
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out.msg_lqbytes = in->msg_qbytes;
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out.msg_lspid = in->msg_lspid;
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out.msg_lrpid = in->msg_lrpid;
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return copy_to_user(buf, &out, sizeof(out));
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}
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default:
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return -EINVAL;
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}
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}
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static inline unsigned long
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copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
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{
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switch (version) {
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case IPC_64:
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if (copy_from_user(out, buf, sizeof(*out)))
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return -EFAULT;
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return 0;
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case IPC_OLD:
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{
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struct msqid_ds tbuf_old;
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if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
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return -EFAULT;
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out->msg_perm.uid = tbuf_old.msg_perm.uid;
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out->msg_perm.gid = tbuf_old.msg_perm.gid;
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out->msg_perm.mode = tbuf_old.msg_perm.mode;
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if (tbuf_old.msg_qbytes == 0)
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out->msg_qbytes = tbuf_old.msg_lqbytes;
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else
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out->msg_qbytes = tbuf_old.msg_qbytes;
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return 0;
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}
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default:
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return -EINVAL;
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}
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}
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|
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/*
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* This function handles some msgctl commands which require the rwsem
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* to be held in write mode.
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* NOTE: no locks must be held, the rwsem is taken inside this function.
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*/
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static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
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struct msqid_ds __user *buf, int version)
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{
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struct kern_ipc_perm *ipcp;
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struct msqid64_ds uninitialized_var(msqid64);
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struct msg_queue *msq;
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int err;
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if (cmd == IPC_SET) {
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if (copy_msqid_from_user(&msqid64, buf, version))
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return -EFAULT;
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}
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down_write(&msg_ids(ns).rwsem);
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rcu_read_lock();
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ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
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&msqid64.msg_perm, msqid64.msg_qbytes);
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if (IS_ERR(ipcp)) {
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err = PTR_ERR(ipcp);
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goto out_unlock1;
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}
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msq = container_of(ipcp, struct msg_queue, q_perm);
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err = security_msg_queue_msgctl(msq, cmd);
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if (err)
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goto out_unlock1;
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switch (cmd) {
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case IPC_RMID:
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ipc_lock_object(&msq->q_perm);
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/* freeque unlocks the ipc object and rcu */
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freeque(ns, ipcp);
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goto out_up;
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case IPC_SET:
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if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
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!capable(CAP_SYS_RESOURCE)) {
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err = -EPERM;
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goto out_unlock1;
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}
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ipc_lock_object(&msq->q_perm);
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err = ipc_update_perm(&msqid64.msg_perm, ipcp);
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if (err)
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goto out_unlock0;
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msq->q_qbytes = msqid64.msg_qbytes;
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msq->q_ctime = get_seconds();
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/* sleeping receivers might be excluded by
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* stricter permissions.
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*/
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expunge_all(msq, -EAGAIN);
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/* sleeping senders might be able to send
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* due to a larger queue size.
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*/
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ss_wakeup(&msq->q_senders, 0);
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break;
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default:
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err = -EINVAL;
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goto out_unlock1;
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}
|
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|
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out_unlock0:
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ipc_unlock_object(&msq->q_perm);
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out_unlock1:
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rcu_read_unlock();
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out_up:
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up_write(&msg_ids(ns).rwsem);
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return err;
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}
|
|
|
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static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
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int cmd, int version, void __user *buf)
|
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{
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int err;
|
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struct msg_queue *msq;
|
|
|
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switch (cmd) {
|
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case IPC_INFO:
|
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case MSG_INFO:
|
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{
|
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struct msginfo msginfo;
|
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int max_id;
|
|
|
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if (!buf)
|
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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);
|
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if (err)
|
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return err;
|
|
|
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memset(&msginfo, 0, sizeof(msginfo));
|
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msginfo.msgmni = ns->msg_ctlmni;
|
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msginfo.msgmax = ns->msg_ctlmax;
|
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msginfo.msgmnb = ns->msg_ctlmnb;
|
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msginfo.msgssz = MSGSSZ;
|
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msginfo.msgseg = MSGSEG;
|
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down_read(&msg_ids(ns).rwsem);
|
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if (cmd == MSG_INFO) {
|
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msginfo.msgpool = msg_ids(ns).in_use;
|
|
msginfo.msgmap = atomic_read(&ns->msg_hdrs);
|
|
msginfo.msgtql = atomic_read(&ns->msg_bytes);
|
|
} else {
|
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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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
|
|
{
|
|
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) {
|
|
/* initialize pipelined send ordering */
|
|
msr->r_msg = NULL;
|
|
wake_up_process(msr->r_tsk);
|
|
/* barrier (B) see barrier comment below */
|
|
smp_wmb();
|
|
msr->r_msg = ERR_PTR(-E2BIG);
|
|
} else {
|
|
msr->r_msg = NULL;
|
|
msq->q_lrpid = task_pid_vnr(msr->r_tsk);
|
|
msq->q_rtime = get_seconds();
|
|
wake_up_process(msr->r_tsk);
|
|
/*
|
|
* Ensure that the wakeup is visible before
|
|
* setting r_msg, as the receiving can otherwise
|
|
* exit - once r_msg is set, the receiver can
|
|
* continue. See lockless receive part 1 and 2
|
|
* in do_msgrcv(). Barrier (B).
|
|
*/
|
|
smp_wmb();
|
|
msr->r_msg = msg;
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
|
|
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 = msgsz;
|
|
|
|
rcu_read_lock();
|
|
msq = msq_obtain_object_check(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
err = PTR_ERR(msq);
|
|
goto out_unlock1;
|
|
}
|
|
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
for (;;) {
|
|
struct msg_sender s;
|
|
|
|
err = -EACCES;
|
|
if (ipcperms(ns, &msq->q_perm, S_IWUGO))
|
|
goto out_unlock0;
|
|
|
|
/* raced with RMID? */
|
|
if (!ipc_valid_object(&msq->q_perm)) {
|
|
err = -EIDRM;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
err = security_msg_queue_msgsnd(msq, msg, msgflg);
|
|
if (err)
|
|
goto out_unlock0;
|
|
|
|
if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
|
|
1 + msq->q_qnum <= msq->q_qbytes) {
|
|
break;
|
|
}
|
|
|
|
/* queue full, wait: */
|
|
if (msgflg & IPC_NOWAIT) {
|
|
err = -EAGAIN;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
/* enqueue the sender and prepare to block */
|
|
ss_add(msq, &s);
|
|
|
|
if (!ipc_rcu_getref(msq)) {
|
|
err = -EIDRM;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
rcu_read_unlock();
|
|
schedule();
|
|
|
|
rcu_read_lock();
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
ipc_rcu_putref(msq, msg_rcu_free);
|
|
/* raced with RMID? */
|
|
if (!ipc_valid_object(&msq->q_perm)) {
|
|
err = -EIDRM;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ss_del(&s);
|
|
|
|
if (signal_pending(current)) {
|
|
err = -ERESTARTNOHAND;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
}
|
|
msq->q_lspid = task_tgid_vnr(current);
|
|
msq->q_stime = get_seconds();
|
|
|
|
if (!pipelined_send(msq, msg)) {
|
|
/* no one is waiting for this message, enqueue it */
|
|
list_add_tail(&msg->m_list, &msq->q_messages);
|
|
msq->q_cbytes += msgsz;
|
|
msq->q_qnum++;
|
|
atomic_add(msgsz, &ns->msg_bytes);
|
|
atomic_inc(&ns->msg_hdrs);
|
|
}
|
|
|
|
err = 0;
|
|
msg = NULL;
|
|
|
|
out_unlock0:
|
|
ipc_unlock_object(&msq->q_perm);
|
|
out_unlock1:
|
|
rcu_read_unlock();
|
|
if (msg != NULL)
|
|
free_msg(msg);
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
|
|
int, msgflg)
|
|
{
|
|
long mtype;
|
|
|
|
if (get_user(mtype, &msgp->mtype))
|
|
return -EFAULT;
|
|
return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
|
|
}
|
|
|
|
static inline int convert_mode(long *msgtyp, int msgflg)
|
|
{
|
|
if (msgflg & MSG_COPY)
|
|
return SEARCH_NUMBER;
|
|
/*
|
|
* find message of correct type.
|
|
* msgtyp = 0 => get first.
|
|
* msgtyp > 0 => get first message of matching type.
|
|
* msgtyp < 0 => get message with least type must be < abs(msgtype).
|
|
*/
|
|
if (*msgtyp == 0)
|
|
return SEARCH_ANY;
|
|
if (*msgtyp < 0) {
|
|
*msgtyp = -*msgtyp;
|
|
return SEARCH_LESSEQUAL;
|
|
}
|
|
if (msgflg & MSG_EXCEPT)
|
|
return SEARCH_NOTEQUAL;
|
|
return SEARCH_EQUAL;
|
|
}
|
|
|
|
static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
|
|
{
|
|
struct msgbuf __user *msgp = dest;
|
|
size_t msgsz;
|
|
|
|
if (put_user(msg->m_type, &msgp->mtype))
|
|
return -EFAULT;
|
|
|
|
msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
|
|
if (store_msg(msgp->mtext, msg, msgsz))
|
|
return -EFAULT;
|
|
return msgsz;
|
|
}
|
|
|
|
#ifdef CONFIG_CHECKPOINT_RESTORE
|
|
/*
|
|
* This function creates new kernel message structure, large enough to store
|
|
* bufsz message bytes.
|
|
*/
|
|
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
|
|
{
|
|
struct msg_msg *copy;
|
|
|
|
/*
|
|
* Create dummy message to copy real message to.
|
|
*/
|
|
copy = load_msg(buf, bufsz);
|
|
if (!IS_ERR(copy))
|
|
copy->m_ts = bufsz;
|
|
return copy;
|
|
}
|
|
|
|
static inline void free_copy(struct msg_msg *copy)
|
|
{
|
|
if (copy)
|
|
free_msg(copy);
|
|
}
|
|
#else
|
|
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
|
|
{
|
|
return ERR_PTR(-ENOSYS);
|
|
}
|
|
|
|
static inline void free_copy(struct msg_msg *copy)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
|
|
{
|
|
struct msg_msg *msg, *found = NULL;
|
|
long count = 0;
|
|
|
|
list_for_each_entry(msg, &msq->q_messages, m_list) {
|
|
if (testmsg(msg, *msgtyp, mode) &&
|
|
!security_msg_queue_msgrcv(msq, msg, current,
|
|
*msgtyp, mode)) {
|
|
if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
|
|
*msgtyp = msg->m_type - 1;
|
|
found = msg;
|
|
} else if (mode == SEARCH_NUMBER) {
|
|
if (*msgtyp == count)
|
|
return msg;
|
|
} else
|
|
return msg;
|
|
count++;
|
|
}
|
|
}
|
|
|
|
return found ?: ERR_PTR(-EAGAIN);
|
|
}
|
|
|
|
long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
|
|
long (*msg_handler)(void __user *, struct msg_msg *, size_t))
|
|
{
|
|
int mode;
|
|
struct msg_queue *msq;
|
|
struct ipc_namespace *ns;
|
|
struct msg_msg *msg, *copy = NULL;
|
|
|
|
ns = current->nsproxy->ipc_ns;
|
|
|
|
if (msqid < 0 || (long) bufsz < 0)
|
|
return -EINVAL;
|
|
|
|
if (msgflg & MSG_COPY) {
|
|
if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
|
|
return -EINVAL;
|
|
copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
|
|
if (IS_ERR(copy))
|
|
return PTR_ERR(copy);
|
|
}
|
|
mode = convert_mode(&msgtyp, msgflg);
|
|
|
|
rcu_read_lock();
|
|
msq = msq_obtain_object_check(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
rcu_read_unlock();
|
|
free_copy(copy);
|
|
return PTR_ERR(msq);
|
|
}
|
|
|
|
for (;;) {
|
|
struct msg_receiver msr_d;
|
|
|
|
msg = ERR_PTR(-EACCES);
|
|
if (ipcperms(ns, &msq->q_perm, S_IRUGO))
|
|
goto out_unlock1;
|
|
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
/* raced with RMID? */
|
|
if (!ipc_valid_object(&msq->q_perm)) {
|
|
msg = ERR_PTR(-EIDRM);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
msg = find_msg(msq, &msgtyp, mode);
|
|
if (!IS_ERR(msg)) {
|
|
/*
|
|
* Found a suitable message.
|
|
* Unlink it from the queue.
|
|
*/
|
|
if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
|
|
msg = ERR_PTR(-E2BIG);
|
|
goto out_unlock0;
|
|
}
|
|
/*
|
|
* If we are copying, then do not unlink message and do
|
|
* not update queue parameters.
|
|
*/
|
|
if (msgflg & MSG_COPY) {
|
|
msg = copy_msg(msg, copy);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
list_del(&msg->m_list);
|
|
msq->q_qnum--;
|
|
msq->q_rtime = get_seconds();
|
|
msq->q_lrpid = task_tgid_vnr(current);
|
|
msq->q_cbytes -= msg->m_ts;
|
|
atomic_sub(msg->m_ts, &ns->msg_bytes);
|
|
atomic_dec(&ns->msg_hdrs);
|
|
ss_wakeup(&msq->q_senders, 0);
|
|
|
|
goto out_unlock0;
|
|
}
|
|
|
|
/* No message waiting. Wait for a message */
|
|
if (msgflg & IPC_NOWAIT) {
|
|
msg = ERR_PTR(-ENOMSG);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
list_add_tail(&msr_d.r_list, &msq->q_receivers);
|
|
msr_d.r_tsk = current;
|
|
msr_d.r_msgtype = msgtyp;
|
|
msr_d.r_mode = mode;
|
|
if (msgflg & MSG_NOERROR)
|
|
msr_d.r_maxsize = INT_MAX;
|
|
else
|
|
msr_d.r_maxsize = bufsz;
|
|
msr_d.r_msg = ERR_PTR(-EAGAIN);
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
rcu_read_unlock();
|
|
schedule();
|
|
|
|
/* Lockless receive, part 1:
|
|
* Disable preemption. We don't hold a reference to the queue
|
|
* and getting a reference would defeat the idea of a lockless
|
|
* operation, thus the code relies on rcu to guarantee the
|
|
* existence of msq:
|
|
* Prior to destruction, expunge_all(-EIRDM) changes r_msg.
|
|
* Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
|
|
* rcu_read_lock() prevents preemption between reading r_msg
|
|
* and acquiring the q_perm.lock in ipc_lock_object().
|
|
*/
|
|
rcu_read_lock();
|
|
|
|
/* Lockless receive, part 2:
|
|
* Wait until pipelined_send or expunge_all are outside of
|
|
* wake_up_process(). There is a race with exit(), see
|
|
* ipc/mqueue.c for the details. The correct serialization
|
|
* ensures that a receiver cannot continue without the wakeup
|
|
* being visibible _before_ setting r_msg:
|
|
*
|
|
* CPU 0 CPU 1
|
|
* <loop receiver>
|
|
* smp_rmb(); (A) <-- pair -. <waker thread>
|
|
* <load ->r_msg> | msr->r_msg = NULL;
|
|
* | wake_up_process();
|
|
* <continue> `------> smp_wmb(); (B)
|
|
* msr->r_msg = msg;
|
|
*
|
|
* Where (A) orders the message value read and where (B) orders
|
|
* the write to the r_msg -- done in both pipelined_send and
|
|
* expunge_all.
|
|
*/
|
|
for (;;) {
|
|
/*
|
|
* Pairs with writer barrier in pipelined_send
|
|
* or expunge_all.
|
|
*/
|
|
smp_rmb(); /* barrier (A) */
|
|
msg = (struct msg_msg *)msr_d.r_msg;
|
|
if (msg)
|
|
break;
|
|
|
|
/*
|
|
* The cpu_relax() call is a compiler barrier
|
|
* which forces everything in this loop to be
|
|
* re-loaded.
|
|
*/
|
|
cpu_relax();
|
|
}
|
|
|
|
/* Lockless receive, part 3:
|
|
* If there is a message or an error then accept it without
|
|
* locking.
|
|
*/
|
|
if (msg != ERR_PTR(-EAGAIN))
|
|
goto out_unlock1;
|
|
|
|
/* Lockless receive, part 3:
|
|
* Acquire the queue spinlock.
|
|
*/
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
/* Lockless receive, part 4:
|
|
* Repeat test after acquiring the spinlock.
|
|
*/
|
|
msg = (struct msg_msg *)msr_d.r_msg;
|
|
if (msg != ERR_PTR(-EAGAIN))
|
|
goto out_unlock0;
|
|
|
|
list_del(&msr_d.r_list);
|
|
if (signal_pending(current)) {
|
|
msg = ERR_PTR(-ERESTARTNOHAND);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
}
|
|
|
|
out_unlock0:
|
|
ipc_unlock_object(&msq->q_perm);
|
|
out_unlock1:
|
|
rcu_read_unlock();
|
|
if (IS_ERR(msg)) {
|
|
free_copy(copy);
|
|
return PTR_ERR(msg);
|
|
}
|
|
|
|
bufsz = msg_handler(buf, msg, bufsz);
|
|
free_msg(msg);
|
|
|
|
return bufsz;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
|
|
long, msgtyp, int, msgflg)
|
|
{
|
|
return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
|
|
}
|
|
|
|
|
|
void msg_init_ns(struct ipc_namespace *ns)
|
|
{
|
|
ns->msg_ctlmax = MSGMAX;
|
|
ns->msg_ctlmnb = MSGMNB;
|
|
ns->msg_ctlmni = MSGMNI;
|
|
|
|
atomic_set(&ns->msg_bytes, 0);
|
|
atomic_set(&ns->msg_hdrs, 0);
|
|
ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
|
|
}
|
|
|
|
#ifdef CONFIG_IPC_NS
|
|
void msg_exit_ns(struct ipc_namespace *ns)
|
|
{
|
|
free_ipcs(ns, &msg_ids(ns), freeque);
|
|
idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
|
|
{
|
|
struct user_namespace *user_ns = seq_user_ns(s);
|
|
struct msg_queue *msq = it;
|
|
|
|
seq_printf(s,
|
|
"%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
|
|
msq->q_perm.key,
|
|
msq->q_perm.id,
|
|
msq->q_perm.mode,
|
|
msq->q_cbytes,
|
|
msq->q_qnum,
|
|
msq->q_lspid,
|
|
msq->q_lrpid,
|
|
from_kuid_munged(user_ns, msq->q_perm.uid),
|
|
from_kgid_munged(user_ns, msq->q_perm.gid),
|
|
from_kuid_munged(user_ns, msq->q_perm.cuid),
|
|
from_kgid_munged(user_ns, msq->q_perm.cgid),
|
|
msq->q_stime,
|
|
msq->q_rtime,
|
|
msq->q_ctime);
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
void __init msg_init(void)
|
|
{
|
|
msg_init_ns(&init_ipc_ns);
|
|
|
|
ipc_init_proc_interface("sysvipc/msg",
|
|
" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
|
|
IPC_MSG_IDS, sysvipc_msg_proc_show);
|
|
}
|