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867 lines
19 KiB
867 lines
19 KiB
/*
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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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#include <linux/capability.h>
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#include <linux/slab.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/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/mutex.h>
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#include <asm/current.h>
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#include <asm/uaccess.h>
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#include "util.h"
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/* sysctl: */
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int msg_ctlmax = MSGMAX;
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int msg_ctlmnb = MSGMNB;
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int msg_ctlmni = MSGMNI;
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/*
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* one msg_receiver structure for each sleeping receiver:
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*/
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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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volatile struct msg_msg *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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static atomic_t msg_bytes = ATOMIC_INIT(0);
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static atomic_t msg_hdrs = ATOMIC_INIT(0);
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static struct ipc_ids msg_ids;
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#define msg_lock(id) ((struct msg_queue *)ipc_lock(&msg_ids, id))
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#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)
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#define msg_rmid(id) ((struct msg_queue *)ipc_rmid(&msg_ids, id))
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#define msg_checkid(msq, msgid) ipc_checkid(&msg_ids, &msq->q_perm, msgid)
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#define msg_buildid(id, seq) ipc_buildid(&msg_ids, id, seq)
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static void freeque(struct msg_queue *msq, int id);
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static int newque(key_t key, int msgflg);
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#ifdef CONFIG_PROC_FS
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static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
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#endif
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void __init msg_init(void)
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{
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ipc_init_ids(&msg_ids, msg_ctlmni);
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ipc_init_proc_interface("sysvipc/msg",
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" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
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&msg_ids,
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sysvipc_msg_proc_show);
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}
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static int newque(key_t key, int msgflg)
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{
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struct msg_queue *msq;
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int id, retval;
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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);
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return retval;
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}
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id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni);
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if (id == -1) {
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security_msg_queue_free(msq);
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ipc_rcu_putref(msq);
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return -ENOSPC;
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}
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msq->q_id = msg_buildid(id, msq->q_perm.seq);
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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 = 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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msg_unlock(msq);
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return msq->q_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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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 list_head *tmp;
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tmp = h->next;
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while (tmp != h) {
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struct msg_sender *mss;
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mss = list_entry(tmp, struct msg_sender, list);
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tmp = tmp->next;
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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 list_head *tmp;
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tmp = msq->q_receivers.next;
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while (tmp != &msq->q_receivers) {
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struct msg_receiver *msr;
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msr = list_entry(tmp, struct msg_receiver, r_list);
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tmp = tmp->next;
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msr->r_msg = NULL;
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wake_up_process(msr->r_tsk);
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smp_mb();
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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
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* array, and cleans up all the messages associated with this queue.
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*
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* msg_ids.mutex and the spinlock for this message queue is hold
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* before freeque() is called. msg_ids.mutex remains locked on exit.
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*/
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static void freeque(struct msg_queue *msq, int id)
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{
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struct list_head *tmp;
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expunge_all(msq, -EIDRM);
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ss_wakeup(&msq->q_senders, 1);
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msq = msg_rmid(id);
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msg_unlock(msq);
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tmp = msq->q_messages.next;
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while (tmp != &msq->q_messages) {
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struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list);
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tmp = tmp->next;
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atomic_dec(&msg_hdrs);
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free_msg(msg);
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}
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atomic_sub(msq->q_cbytes, &msg_bytes);
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security_msg_queue_free(msq);
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ipc_rcu_putref(msq);
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}
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asmlinkage long sys_msgget(key_t key, int msgflg)
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{
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struct msg_queue *msq;
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int id, ret = -EPERM;
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mutex_lock(&msg_ids.mutex);
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if (key == IPC_PRIVATE)
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ret = newque(key, msgflg);
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else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */
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if (!(msgflg & IPC_CREAT))
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ret = -ENOENT;
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else
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ret = newque(key, msgflg);
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} else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
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ret = -EEXIST;
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} else {
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msq = msg_lock(id);
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BUG_ON(msq == NULL);
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if (ipcperms(&msq->q_perm, msgflg))
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ret = -EACCES;
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else {
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int qid = msg_buildid(id, msq->q_perm.seq);
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ret = security_msg_queue_associate(msq, msgflg);
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if (!ret)
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ret = qid;
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}
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msg_unlock(msq);
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}
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mutex_unlock(&msg_ids.mutex);
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return ret;
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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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struct msq_setbuf {
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unsigned long qbytes;
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uid_t uid;
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gid_t gid;
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mode_t mode;
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};
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static inline unsigned long
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copy_msqid_from_user(struct msq_setbuf *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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{
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struct msqid64_ds tbuf;
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if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
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return -EFAULT;
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|
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out->qbytes = tbuf.msg_qbytes;
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out->uid = tbuf.msg_perm.uid;
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out->gid = tbuf.msg_perm.gid;
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out->mode = tbuf.msg_perm.mode;
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|
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return 0;
|
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}
|
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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->uid = tbuf_old.msg_perm.uid;
|
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out->gid = tbuf_old.msg_perm.gid;
|
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out->mode = tbuf_old.msg_perm.mode;
|
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|
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if (tbuf_old.msg_qbytes == 0)
|
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out->qbytes = tbuf_old.msg_lqbytes;
|
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else
|
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out->qbytes = tbuf_old.msg_qbytes;
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|
|
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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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asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
|
|
{
|
|
struct kern_ipc_perm *ipcp;
|
|
struct msq_setbuf setbuf;
|
|
struct msg_queue *msq;
|
|
int err, version;
|
|
|
|
if (msqid < 0 || cmd < 0)
|
|
return -EINVAL;
|
|
|
|
version = ipc_parse_version(&cmd);
|
|
|
|
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 = msg_ctlmni;
|
|
msginfo.msgmax = msg_ctlmax;
|
|
msginfo.msgmnb = msg_ctlmnb;
|
|
msginfo.msgssz = MSGSSZ;
|
|
msginfo.msgseg = MSGSEG;
|
|
mutex_lock(&msg_ids.mutex);
|
|
if (cmd == MSG_INFO) {
|
|
msginfo.msgpool = msg_ids.in_use;
|
|
msginfo.msgmap = atomic_read(&msg_hdrs);
|
|
msginfo.msgtql = atomic_read(&msg_bytes);
|
|
} else {
|
|
msginfo.msgmap = MSGMAP;
|
|
msginfo.msgpool = MSGPOOL;
|
|
msginfo.msgtql = MSGTQL;
|
|
}
|
|
max_id = msg_ids.max_id;
|
|
mutex_unlock(&msg_ids.mutex);
|
|
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;
|
|
if (cmd == MSG_STAT && msqid >= msg_ids.entries->size)
|
|
return -EINVAL;
|
|
|
|
memset(&tbuf, 0, sizeof(tbuf));
|
|
|
|
msq = msg_lock(msqid);
|
|
if (msq == NULL)
|
|
return -EINVAL;
|
|
|
|
if (cmd == MSG_STAT) {
|
|
success_return = msg_buildid(msqid, msq->q_perm.seq);
|
|
} else {
|
|
err = -EIDRM;
|
|
if (msg_checkid(msq, msqid))
|
|
goto out_unlock;
|
|
success_return = 0;
|
|
}
|
|
err = -EACCES;
|
|
if (ipcperms(&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;
|
|
msg_unlock(msq);
|
|
if (copy_msqid_to_user(buf, &tbuf, version))
|
|
return -EFAULT;
|
|
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;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
mutex_lock(&msg_ids.mutex);
|
|
msq = msg_lock(msqid);
|
|
err = -EINVAL;
|
|
if (msq == NULL)
|
|
goto out_up;
|
|
|
|
err = -EIDRM;
|
|
if (msg_checkid(msq, msqid))
|
|
goto out_unlock_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 > 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(msq, msqid);
|
|
break;
|
|
}
|
|
err = 0;
|
|
out_up:
|
|
mutex_unlock(&msg_ids.mutex);
|
|
return err;
|
|
out_unlock_up:
|
|
msg_unlock(msq);
|
|
goto out_up;
|
|
out_unlock:
|
|
msg_unlock(msq);
|
|
return err;
|
|
}
|
|
|
|
static int testmsg(struct msg_msg *msg, long type, int mode)
|
|
{
|
|
switch(mode)
|
|
{
|
|
case SEARCH_ANY:
|
|
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 list_head *tmp;
|
|
|
|
tmp = msq->q_receivers.next;
|
|
while (tmp != &msq->q_receivers) {
|
|
struct msg_receiver *msr;
|
|
|
|
msr = list_entry(tmp, struct msg_receiver, r_list);
|
|
tmp = tmp->next;
|
|
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) {
|
|
msr->r_msg = NULL;
|
|
wake_up_process(msr->r_tsk);
|
|
smp_mb();
|
|
msr->r_msg = ERR_PTR(-E2BIG);
|
|
} else {
|
|
msr->r_msg = NULL;
|
|
msq->q_lrpid = msr->r_tsk->pid;
|
|
msq->q_rtime = get_seconds();
|
|
wake_up_process(msr->r_tsk);
|
|
smp_mb();
|
|
msr->r_msg = msg;
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
asmlinkage long
|
|
sys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg)
|
|
{
|
|
struct msg_queue *msq;
|
|
struct msg_msg *msg;
|
|
long mtype;
|
|
int err;
|
|
|
|
if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0)
|
|
return -EINVAL;
|
|
if (get_user(mtype, &msgp->mtype))
|
|
return -EFAULT;
|
|
if (mtype < 1)
|
|
return -EINVAL;
|
|
|
|
msg = load_msg(msgp->mtext, msgsz);
|
|
if (IS_ERR(msg))
|
|
return PTR_ERR(msg);
|
|
|
|
msg->m_type = mtype;
|
|
msg->m_ts = msgsz;
|
|
|
|
msq = msg_lock(msqid);
|
|
err = -EINVAL;
|
|
if (msq == NULL)
|
|
goto out_free;
|
|
|
|
err= -EIDRM;
|
|
if (msg_checkid(msq, msqid))
|
|
goto out_unlock_free;
|
|
|
|
for (;;) {
|
|
struct msg_sender s;
|
|
|
|
err = -EACCES;
|
|
if (ipcperms(&msq->q_perm, S_IWUGO))
|
|
goto out_unlock_free;
|
|
|
|
err = security_msg_queue_msgsnd(msq, msg, msgflg);
|
|
if (err)
|
|
goto out_unlock_free;
|
|
|
|
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_unlock_free;
|
|
}
|
|
ss_add(msq, &s);
|
|
ipc_rcu_getref(msq);
|
|
msg_unlock(msq);
|
|
schedule();
|
|
|
|
ipc_lock_by_ptr(&msq->q_perm);
|
|
ipc_rcu_putref(msq);
|
|
if (msq->q_perm.deleted) {
|
|
err = -EIDRM;
|
|
goto out_unlock_free;
|
|
}
|
|
ss_del(&s);
|
|
|
|
if (signal_pending(current)) {
|
|
err = -ERESTARTNOHAND;
|
|
goto out_unlock_free;
|
|
}
|
|
}
|
|
|
|
msq->q_lspid = current->tgid;
|
|
msq->q_stime = get_seconds();
|
|
|
|
if (!pipelined_send(msq, msg)) {
|
|
/* noone 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, &msg_bytes);
|
|
atomic_inc(&msg_hdrs);
|
|
}
|
|
|
|
err = 0;
|
|
msg = NULL;
|
|
|
|
out_unlock_free:
|
|
msg_unlock(msq);
|
|
out_free:
|
|
if (msg != NULL)
|
|
free_msg(msg);
|
|
return err;
|
|
}
|
|
|
|
static inline int convert_mode(long *msgtyp, int msgflg)
|
|
{
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
asmlinkage long sys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
|
|
long msgtyp, int msgflg)
|
|
{
|
|
struct msg_queue *msq;
|
|
struct msg_msg *msg;
|
|
int mode;
|
|
|
|
if (msqid < 0 || (long) msgsz < 0)
|
|
return -EINVAL;
|
|
mode = convert_mode(&msgtyp, msgflg);
|
|
|
|
msq = msg_lock(msqid);
|
|
if (msq == NULL)
|
|
return -EINVAL;
|
|
|
|
msg = ERR_PTR(-EIDRM);
|
|
if (msg_checkid(msq, msqid))
|
|
goto out_unlock;
|
|
|
|
for (;;) {
|
|
struct msg_receiver msr_d;
|
|
struct list_head *tmp;
|
|
|
|
msg = ERR_PTR(-EACCES);
|
|
if (ipcperms(&msq->q_perm, S_IRUGO))
|
|
goto out_unlock;
|
|
|
|
msg = ERR_PTR(-EAGAIN);
|
|
tmp = msq->q_messages.next;
|
|
while (tmp != &msq->q_messages) {
|
|
struct msg_msg *walk_msg;
|
|
|
|
walk_msg = list_entry(tmp, struct msg_msg, m_list);
|
|
if (testmsg(walk_msg, msgtyp, mode) &&
|
|
!security_msg_queue_msgrcv(msq, walk_msg, current,
|
|
msgtyp, mode)) {
|
|
|
|
msg = walk_msg;
|
|
if (mode == SEARCH_LESSEQUAL &&
|
|
walk_msg->m_type != 1) {
|
|
msg = walk_msg;
|
|
msgtyp = walk_msg->m_type - 1;
|
|
} else {
|
|
msg = walk_msg;
|
|
break;
|
|
}
|
|
}
|
|
tmp = tmp->next;
|
|
}
|
|
if (!IS_ERR(msg)) {
|
|
/*
|
|
* Found a suitable message.
|
|
* Unlink it from the queue.
|
|
*/
|
|
if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
|
|
msg = ERR_PTR(-E2BIG);
|
|
goto out_unlock;
|
|
}
|
|
list_del(&msg->m_list);
|
|
msq->q_qnum--;
|
|
msq->q_rtime = get_seconds();
|
|
msq->q_lrpid = current->tgid;
|
|
msq->q_cbytes -= msg->m_ts;
|
|
atomic_sub(msg->m_ts, &msg_bytes);
|
|
atomic_dec(&msg_hdrs);
|
|
ss_wakeup(&msq->q_senders, 0);
|
|
msg_unlock(msq);
|
|
break;
|
|
}
|
|
/* No message waiting. Wait for a message */
|
|
if (msgflg & IPC_NOWAIT) {
|
|
msg = ERR_PTR(-ENOMSG);
|
|
goto out_unlock;
|
|
}
|
|
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 = msgsz;
|
|
msr_d.r_msg = ERR_PTR(-EAGAIN);
|
|
current->state = TASK_INTERRUPTIBLE;
|
|
msg_unlock(msq);
|
|
|
|
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
|
|
* existance 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 the spin_lock() inside ipc_lock_by_ptr().
|
|
*/
|
|
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.
|
|
*/
|
|
msg = (struct msg_msg*)msr_d.r_msg;
|
|
while (msg == NULL) {
|
|
cpu_relax();
|
|
msg = (struct msg_msg *)msr_d.r_msg;
|
|
}
|
|
|
|
/* Lockless receive, part 3:
|
|
* If there is a message or an error then accept it without
|
|
* locking.
|
|
*/
|
|
if (msg != ERR_PTR(-EAGAIN)) {
|
|
rcu_read_unlock();
|
|
break;
|
|
}
|
|
|
|
/* Lockless receive, part 3:
|
|
* Acquire the queue spinlock.
|
|
*/
|
|
ipc_lock_by_ptr(&msq->q_perm);
|
|
rcu_read_unlock();
|
|
|
|
/* 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_unlock;
|
|
|
|
list_del(&msr_d.r_list);
|
|
if (signal_pending(current)) {
|
|
msg = ERR_PTR(-ERESTARTNOHAND);
|
|
out_unlock:
|
|
msg_unlock(msq);
|
|
break;
|
|
}
|
|
}
|
|
if (IS_ERR(msg))
|
|
return PTR_ERR(msg);
|
|
|
|
msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
|
|
if (put_user (msg->m_type, &msgp->mtype) ||
|
|
store_msg(msgp->mtext, msg, msgsz)) {
|
|
msgsz = -EFAULT;
|
|
}
|
|
free_msg(msg);
|
|
|
|
return msgsz;
|
|
}
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
|
|
{
|
|
struct msg_queue *msq = it;
|
|
|
|
return seq_printf(s,
|
|
"%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
|
|
msq->q_perm.key,
|
|
msq->q_id,
|
|
msq->q_perm.mode,
|
|
msq->q_cbytes,
|
|
msq->q_qnum,
|
|
msq->q_lspid,
|
|
msq->q_lrpid,
|
|
msq->q_perm.uid,
|
|
msq->q_perm.gid,
|
|
msq->q_perm.cuid,
|
|
msq->q_perm.cgid,
|
|
msq->q_stime,
|
|
msq->q_rtime,
|
|
msq->q_ctime);
|
|
}
|
|
#endif
|
|
|