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ipc/msg.c
20.5 KB
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/* * linux/ipc/msg.c |
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* Copyright (C) 1992 Krishna Balasubramanian |
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* * 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 |
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* (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
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* * support for audit of ipc object properties and permission changes * Dustin Kirkland <dustin.kirkland@us.ibm.com> |
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* * namespaces support * OpenVZ, SWsoft Inc. * Pavel Emelianov <xemul@openvz.org> |
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*/ |
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#include <linux/capability.h> |
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#include <linux/slab.h> #include <linux/msg.h> #include <linux/spinlock.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/list.h> #include <linux/security.h> #include <linux/sched.h> #include <linux/syscalls.h> #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 <linux/nsproxy.h> |
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#include <asm/current.h> #include <asm/uaccess.h> #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; struct task_struct *r_tsk; |
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int r_mode; long r_msgtype; long r_maxsize; |
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struct msg_msg *volatile r_msg; |
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}; /* one msg_sender for each sleeping sender */ struct msg_sender { |
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struct list_head list; struct task_struct *tsk; |
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}; #define SEARCH_ANY 1 #define SEARCH_EQUAL 2 #define SEARCH_NOTEQUAL 3 #define SEARCH_LESSEQUAL 4 |
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static atomic_t msg_bytes = ATOMIC_INIT(0); static atomic_t msg_hdrs = ATOMIC_INIT(0); |
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static struct ipc_ids init_msg_ids; |
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#define msg_ids(ns) (*((ns)->ids[IPC_MSG_IDS])) |
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#define msg_lock(ns, id) ((struct msg_queue*)ipc_lock(&msg_ids(ns), id)) #define msg_unlock(msq) ipc_unlock(&(msq)->q_perm) #define msg_rmid(ns, id) ((struct msg_queue*)ipc_rmid(&msg_ids(ns), id)) #define msg_checkid(ns, msq, msgid) \ ipc_checkid(&msg_ids(ns), &msq->q_perm, msgid) #define msg_buildid(ns, id, seq) \ ipc_buildid(&msg_ids(ns), id, seq) static void freeque (struct ipc_namespace *ns, struct msg_queue *msq, int id); static int newque (struct ipc_namespace *ns, 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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static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids) |
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{ ns->ids[IPC_MSG_IDS] = ids; ns->msg_ctlmax = MSGMAX; ns->msg_ctlmnb = MSGMNB; ns->msg_ctlmni = MSGMNI; ipc_init_ids(ids, ns->msg_ctlmni); } |
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int msg_init_ns(struct ipc_namespace *ns) { struct ipc_ids *ids; ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL); if (ids == NULL) return -ENOMEM; __msg_init_ns(ns, ids); return 0; } void msg_exit_ns(struct ipc_namespace *ns) { int i; struct msg_queue *msq; mutex_lock(&msg_ids(ns).mutex); for (i = 0; i <= msg_ids(ns).max_id; i++) { msq = msg_lock(ns, i); if (msq == NULL) continue; freeque(ns, msq, i); } mutex_unlock(&msg_ids(ns).mutex); |
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ipc_fini_ids(ns->ids[IPC_MSG_IDS]); |
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kfree(ns->ids[IPC_MSG_IDS]); ns->ids[IPC_MSG_IDS] = NULL; } |
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|
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void __init msg_init(void) |
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{ |
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__msg_init_ns(&init_ipc_ns, &init_msg_ids); |
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ipc_init_proc_interface("sysvipc/msg", " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime ", |
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IPC_MSG_IDS, sysvipc_msg_proc_show); |
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} |
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static int newque (struct ipc_namespace *ns, 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)); 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; msq->q_perm.security = NULL; retval = security_msg_queue_alloc(msq); if (retval) { ipc_rcu_putref(msq); return retval; } |
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id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); |
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if (id == -1) { |
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security_msg_queue_free(msq); ipc_rcu_putref(msq); return -ENOSPC; } |
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msq->q_id = msg_buildid(ns, id, msq->q_perm.seq); |
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msq->q_stime = msq->q_rtime = 0; msq->q_ctime = get_seconds(); 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; INIT_LIST_HEAD(&msq->q_messages); INIT_LIST_HEAD(&msq->q_receivers); INIT_LIST_HEAD(&msq->q_senders); 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; current->state = TASK_INTERRUPTIBLE; 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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static void ss_wakeup(struct list_head *h, int kill) |
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{ struct list_head *tmp; tmp = h->next; while (tmp != h) { |
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struct msg_sender *mss; mss = list_entry(tmp, struct msg_sender, list); |
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tmp = tmp->next; |
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if (kill) mss->list.next = NULL; |
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wake_up_process(mss->tsk); } } |
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static void expunge_all(struct msg_queue *msq, int res) |
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{ struct list_head *tmp; tmp = msq->q_receivers.next; while (tmp != &msq->q_receivers) { |
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struct msg_receiver *msr; msr = list_entry(tmp, struct msg_receiver, r_list); |
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tmp = tmp->next; msr->r_msg = NULL; wake_up_process(msr->r_tsk); smp_mb(); msr->r_msg = ERR_PTR(res); } } |
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/* * freeque() wakes up waiters on the sender and receiver waiting queue, * 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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* msg_ids.mutex and the spinlock for this message queue is hold * before freeque() is called. msg_ids.mutex remains locked on exit. |
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*/ |
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static void freeque(struct ipc_namespace *ns, struct msg_queue *msq, int id) |
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{ struct list_head *tmp; |
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expunge_all(msq, -EIDRM); ss_wakeup(&msq->q_senders, 1); |
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msq = msg_rmid(ns, 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) { struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list); |
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tmp = tmp->next; atomic_dec(&msg_hdrs); free_msg(msg); } atomic_sub(msq->q_cbytes, &msg_bytes); security_msg_queue_free(msq); ipc_rcu_putref(msq); } |
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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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struct ipc_namespace *ns; ns = current->nsproxy->ipc_ns; |
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mutex_lock(&msg_ids(ns).mutex); |
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if (key == IPC_PRIVATE) |
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ret = newque(ns, key, msgflg); else if ((id = ipc_findkey(&msg_ids(ns), key)) == -1) { /* key not used */ |
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if (!(msgflg & IPC_CREAT)) ret = -ENOENT; else |
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ret = newque(ns, key, msgflg); |
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} else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) { ret = -EEXIST; } else { |
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msq = msg_lock(ns, id); |
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BUG_ON(msq == NULL); |
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if (ipcperms(&msq->q_perm, msgflg)) ret = -EACCES; else { |
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int qid = msg_buildid(ns, id, msq->q_perm.seq); |
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ret = security_msg_queue_associate(msq, msgflg); |
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if (!ret) ret = qid; } msg_unlock(msq); } |
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mutex_unlock(&msg_ids(ns).mutex); |
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return ret; } |
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static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) |
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{ switch(version) { 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); out.msg_stime = in->msg_stime; out.msg_rtime = in->msg_rtime; 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; else out.msg_cbytes = in->msg_cbytes; 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; else 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; 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; |
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return copy_to_user(buf, &out, sizeof(out)); } |
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default: return -EINVAL; } } struct msq_setbuf { unsigned long qbytes; uid_t uid; gid_t gid; mode_t mode; }; |
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static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version) |
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{ switch(version) { 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; out->qbytes = tbuf.msg_qbytes; out->uid = tbuf.msg_perm.uid; out->gid = tbuf.msg_perm.gid; out->mode = tbuf.msg_perm.mode; return 0; |
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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; out->uid = tbuf_old.msg_perm.uid; out->gid = tbuf_old.msg_perm.gid; out->mode = tbuf_old.msg_perm.mode; |
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if (tbuf_old.msg_qbytes == 0) |
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out->qbytes = tbuf_old.msg_lqbytes; else out->qbytes = tbuf_old.msg_qbytes; return 0; |
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} |
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default: return -EINVAL; } } |
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asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) |
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{ |
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struct kern_ipc_perm *ipcp; |
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struct msq_setbuf uninitialized_var(setbuf); |
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struct msg_queue *msq; int err, version; |
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struct ipc_namespace *ns; |
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if (msqid < 0 || cmd < 0) return -EINVAL; version = ipc_parse_version(&cmd); |
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ns = current->nsproxy->ipc_ns; |
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switch (cmd) { |
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case IPC_INFO: case MSG_INFO: { |
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struct msginfo msginfo; int max_id; |
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|
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if (!buf) return -EFAULT; |
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/* * We must not return kernel stack data. |
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* due to padding, it's not enough * to set all member fields. */ |
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err = security_msg_queue_msgctl(NULL, cmd); if (err) return err; |
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memset(&msginfo, 0, sizeof(msginfo)); |
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msginfo.msgmni = ns->msg_ctlmni; msginfo.msgmax = ns->msg_ctlmax; msginfo.msgmnb = ns->msg_ctlmnb; |
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msginfo.msgssz = MSGSSZ; msginfo.msgseg = MSGSEG; |
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mutex_lock(&msg_ids(ns).mutex); |
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if (cmd == MSG_INFO) { |
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msginfo.msgpool = msg_ids(ns).in_use; |
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msginfo.msgmap = atomic_read(&msg_hdrs); msginfo.msgtql = atomic_read(&msg_bytes); } else { msginfo.msgmap = MSGMAP; msginfo.msgpool = MSGPOOL; msginfo.msgtql = MSGTQL; } |
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max_id = msg_ids(ns).max_id; mutex_unlock(&msg_ids(ns).mutex); |
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if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) |
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return -EFAULT; |
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return (max_id < 0) ? 0 : max_id; |
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} case MSG_STAT: case IPC_STAT: { struct msqid64_ds tbuf; int success_return; |
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if (!buf) return -EFAULT; |
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if (cmd == MSG_STAT && msqid >= msg_ids(ns).entries->size) |
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return -EINVAL; |
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memset(&tbuf, 0, sizeof(tbuf)); |
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msq = msg_lock(ns, msqid); |
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if (msq == NULL) return -EINVAL; |
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if (cmd == MSG_STAT) { |
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success_return = msg_buildid(ns, msqid, msq->q_perm.seq); |
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} else { err = -EIDRM; |
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if (msg_checkid(ns, msq, msqid)) |
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goto out_unlock; success_return = 0; } err = -EACCES; |
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if (ipcperms(&msq->q_perm, S_IRUGO)) |
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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; |
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if (copy_msqid_from_user(&setbuf, buf, version)) |
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return -EFAULT; |
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break; case IPC_RMID: break; default: return -EINVAL; } |
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mutex_lock(&msg_ids(ns).mutex); msq = msg_lock(ns, msqid); |
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err = -EINVAL; |
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if (msq == NULL) goto out_up; err = -EIDRM; |
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if (msg_checkid(ns, msq, msqid)) |
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goto out_unlock_up; ipcp = &msq->q_perm; |
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err = audit_ipc_obj(ipcp); if (err) goto out_unlock_up; |
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if (cmd == IPC_SET) { |
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err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid, setbuf.mode); |
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|
483 484 485 |
if (err) goto out_unlock_up; } |
073115d6b
|
486 |
|
1da177e4c
|
487 |
err = -EPERM; |
5a06a363e
|
488 |
if (current->euid != ipcp->cuid && |
1da177e4c
|
489 |
current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) |
5a06a363e
|
490 |
/* We _could_ check for CAP_CHOWN above, but we don't */ |
1da177e4c
|
491 492 493 494 495 496 497 498 499 500 |
goto out_unlock_up; err = security_msg_queue_msgctl(msq, cmd); if (err) goto out_unlock_up; switch (cmd) { case IPC_SET: { err = -EPERM; |
1e7869373
|
501 |
if (setbuf.qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) |
1da177e4c
|
502 503 504 505 506 507 |
goto out_unlock_up; msq->q_qbytes = setbuf.qbytes; ipcp->uid = setbuf.uid; ipcp->gid = setbuf.gid; |
5a06a363e
|
508 509 |
ipcp->mode = (ipcp->mode & ~S_IRWXUGO) | (S_IRWXUGO & setbuf.mode); |
1da177e4c
|
510 511 512 513 |
msq->q_ctime = get_seconds(); /* sleeping receivers might be excluded by * stricter permissions. */ |
5a06a363e
|
514 |
expunge_all(msq, -EAGAIN); |
1da177e4c
|
515 516 517 |
/* sleeping senders might be able to send * due to a larger queue size. */ |
5a06a363e
|
518 |
ss_wakeup(&msq->q_senders, 0); |
1da177e4c
|
519 520 521 522 |
msg_unlock(msq); break; } case IPC_RMID: |
1e7869373
|
523 |
freeque(ns, msq, msqid); |
1da177e4c
|
524 525 526 527 |
break; } err = 0; out_up: |
1e7869373
|
528 |
mutex_unlock(&msg_ids(ns).mutex); |
1da177e4c
|
529 530 531 532 533 534 535 536 |
return err; out_unlock_up: msg_unlock(msq); goto out_up; out_unlock: msg_unlock(msq); return err; } |
5a06a363e
|
537 |
static int testmsg(struct msg_msg *msg, long type, int mode) |
1da177e4c
|
538 539 540 541 542 543 |
{ switch(mode) { case SEARCH_ANY: return 1; case SEARCH_LESSEQUAL: |
5a06a363e
|
544 |
if (msg->m_type <=type) |
1da177e4c
|
545 546 547 |
return 1; break; case SEARCH_EQUAL: |
5a06a363e
|
548 |
if (msg->m_type == type) |
1da177e4c
|
549 550 551 |
return 1; break; case SEARCH_NOTEQUAL: |
5a06a363e
|
552 |
if (msg->m_type != type) |
1da177e4c
|
553 554 555 556 557 |
return 1; break; } return 0; } |
5a06a363e
|
558 |
static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg) |
1da177e4c
|
559 |
{ |
5a06a363e
|
560 |
struct list_head *tmp; |
1da177e4c
|
561 562 563 |
tmp = msq->q_receivers.next; while (tmp != &msq->q_receivers) { |
5a06a363e
|
564 565 566 |
struct msg_receiver *msr; msr = list_entry(tmp, struct msg_receiver, r_list); |
1da177e4c
|
567 |
tmp = tmp->next; |
5a06a363e
|
568 569 570 |
if (testmsg(msg, msr->r_msgtype, msr->r_mode) && !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) { |
1da177e4c
|
571 |
list_del(&msr->r_list); |
5a06a363e
|
572 |
if (msr->r_maxsize < msg->m_ts) { |
1da177e4c
|
573 574 575 576 577 578 579 580 581 582 583 |
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; |
5a06a363e
|
584 |
|
1da177e4c
|
585 586 587 588 589 590 |
return 1; } } } return 0; } |
651971cb7
|
591 592 |
long do_msgsnd(int msqid, long mtype, void __user *mtext, size_t msgsz, int msgflg) |
1da177e4c
|
593 594 595 |
{ struct msg_queue *msq; struct msg_msg *msg; |
1da177e4c
|
596 |
int err; |
1e7869373
|
597 598 599 |
struct ipc_namespace *ns; ns = current->nsproxy->ipc_ns; |
5a06a363e
|
600 |
|
1e7869373
|
601 |
if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) |
1da177e4c
|
602 |
return -EINVAL; |
1da177e4c
|
603 604 |
if (mtype < 1) return -EINVAL; |
651971cb7
|
605 |
msg = load_msg(mtext, msgsz); |
5a06a363e
|
606 |
if (IS_ERR(msg)) |
1da177e4c
|
607 608 609 610 |
return PTR_ERR(msg); msg->m_type = mtype; msg->m_ts = msgsz; |
1e7869373
|
611 |
msq = msg_lock(ns, msqid); |
5a06a363e
|
612 613 |
err = -EINVAL; if (msq == NULL) |
1da177e4c
|
614 615 616 |
goto out_free; err= -EIDRM; |
1e7869373
|
617 |
if (msg_checkid(ns, msq, msqid)) |
1da177e4c
|
618 619 620 621 |
goto out_unlock_free; for (;;) { struct msg_sender s; |
5a06a363e
|
622 |
err = -EACCES; |
1da177e4c
|
623 624 625 626 627 628 |
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; |
5a06a363e
|
629 |
if (msgsz + msq->q_cbytes <= msq->q_qbytes && |
1da177e4c
|
630 631 632 633 634 |
1 + msq->q_qnum <= msq->q_qbytes) { break; } /* queue full, wait: */ |
5a06a363e
|
635 636 |
if (msgflg & IPC_NOWAIT) { err = -EAGAIN; |
1da177e4c
|
637 638 639 640 641 642 643 644 645 646 647 648 649 650 |
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); |
5a06a363e
|
651 |
|
1da177e4c
|
652 |
if (signal_pending(current)) { |
5a06a363e
|
653 |
err = -ERESTARTNOHAND; |
1da177e4c
|
654 655 656 657 658 659 |
goto out_unlock_free; } } msq->q_lspid = current->tgid; msq->q_stime = get_seconds(); |
5a06a363e
|
660 |
if (!pipelined_send(msq, msg)) { |
1da177e4c
|
661 |
/* noone is waiting for this message, enqueue it */ |
5a06a363e
|
662 |
list_add_tail(&msg->m_list, &msq->q_messages); |
1da177e4c
|
663 664 |
msq->q_cbytes += msgsz; msq->q_qnum++; |
5a06a363e
|
665 |
atomic_add(msgsz, &msg_bytes); |
1da177e4c
|
666 667 |
atomic_inc(&msg_hdrs); } |
5a06a363e
|
668 |
|
1da177e4c
|
669 670 671 672 673 674 |
err = 0; msg = NULL; out_unlock_free: msg_unlock(msq); out_free: |
5a06a363e
|
675 |
if (msg != NULL) |
1da177e4c
|
676 677 678 |
free_msg(msg); return err; } |
651971cb7
|
679 680 681 682 683 684 685 686 687 |
asmlinkage long sys_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); } |
5a06a363e
|
688 |
static inline int convert_mode(long *msgtyp, int msgflg) |
1da177e4c
|
689 |
{ |
5a06a363e
|
690 |
/* |
1da177e4c
|
691 692 693 |
* find message of correct type. * msgtyp = 0 => get first. * msgtyp > 0 => get first message of matching type. |
5a06a363e
|
694 |
* msgtyp < 0 => get message with least type must be < abs(msgtype). |
1da177e4c
|
695 |
*/ |
5a06a363e
|
696 |
if (*msgtyp == 0) |
1da177e4c
|
697 |
return SEARCH_ANY; |
5a06a363e
|
698 699 |
if (*msgtyp < 0) { *msgtyp = -*msgtyp; |
1da177e4c
|
700 701 |
return SEARCH_LESSEQUAL; } |
5a06a363e
|
702 |
if (msgflg & MSG_EXCEPT) |
1da177e4c
|
703 704 705 |
return SEARCH_NOTEQUAL; return SEARCH_EQUAL; } |
651971cb7
|
706 707 |
long do_msgrcv(int msqid, long *pmtype, void __user *mtext, size_t msgsz, long msgtyp, int msgflg) |
1da177e4c
|
708 709 710 711 |
{ struct msg_queue *msq; struct msg_msg *msg; int mode; |
1e7869373
|
712 |
struct ipc_namespace *ns; |
1da177e4c
|
713 714 715 |
if (msqid < 0 || (long) msgsz < 0) return -EINVAL; |
5a06a363e
|
716 |
mode = convert_mode(&msgtyp, msgflg); |
1e7869373
|
717 |
ns = current->nsproxy->ipc_ns; |
1da177e4c
|
718 |
|
1e7869373
|
719 |
msq = msg_lock(ns, msqid); |
5a06a363e
|
720 |
if (msq == NULL) |
1da177e4c
|
721 722 723 |
return -EINVAL; msg = ERR_PTR(-EIDRM); |
1e7869373
|
724 |
if (msg_checkid(ns, msq, msqid)) |
1da177e4c
|
725 726 727 728 |
goto out_unlock; for (;;) { struct msg_receiver msr_d; |
5a06a363e
|
729 |
struct list_head *tmp; |
1da177e4c
|
730 731 |
msg = ERR_PTR(-EACCES); |
5a06a363e
|
732 |
if (ipcperms(&msq->q_perm, S_IRUGO)) |
1da177e4c
|
733 734 735 736 737 738 |
goto out_unlock; msg = ERR_PTR(-EAGAIN); tmp = msq->q_messages.next; while (tmp != &msq->q_messages) { struct msg_msg *walk_msg; |
5a06a363e
|
739 740 741 742 743 |
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)) { |
1da177e4c
|
744 |
msg = walk_msg; |
5a06a363e
|
745 746 747 748 |
if (mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) { msg = walk_msg; msgtyp = walk_msg->m_type - 1; |
1da177e4c
|
749 |
} else { |
5a06a363e
|
750 |
msg = walk_msg; |
1da177e4c
|
751 752 753 754 755 |
break; } } tmp = tmp->next; } |
5a06a363e
|
756 757 758 759 760 |
if (!IS_ERR(msg)) { /* * Found a suitable message. * Unlink it from the queue. */ |
1da177e4c
|
761 762 763 764 765 766 767 768 769 |
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; |
5a06a363e
|
770 |
atomic_sub(msg->m_ts, &msg_bytes); |
1da177e4c
|
771 |
atomic_dec(&msg_hdrs); |
5a06a363e
|
772 |
ss_wakeup(&msq->q_senders, 0); |
1da177e4c
|
773 774 775 776 777 778 779 780 |
msg_unlock(msq); break; } /* No message waiting. Wait for a message */ if (msgflg & IPC_NOWAIT) { msg = ERR_PTR(-ENOMSG); goto out_unlock; } |
5a06a363e
|
781 |
list_add_tail(&msr_d.r_list, &msq->q_receivers); |
1da177e4c
|
782 783 784 |
msr_d.r_tsk = current; msr_d.r_msgtype = msgtyp; msr_d.r_mode = mode; |
5a06a363e
|
785 |
if (msgflg & MSG_NOERROR) |
1da177e4c
|
786 |
msr_d.r_maxsize = INT_MAX; |
5a06a363e
|
787 |
else |
1da177e4c
|
788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 |
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. */ |
5a06a363e
|
812 |
msg = (struct msg_msg*)msr_d.r_msg; |
1da177e4c
|
813 814 |
while (msg == NULL) { cpu_relax(); |
5a06a363e
|
815 |
msg = (struct msg_msg *)msr_d.r_msg; |
1da177e4c
|
816 817 818 819 820 821 |
} /* Lockless receive, part 3: * If there is a message or an error then accept it without * locking. */ |
5a06a363e
|
822 |
if (msg != ERR_PTR(-EAGAIN)) { |
1da177e4c
|
823 824 825 826 827 828 829 830 831 832 833 834 835 836 |
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; |
5a06a363e
|
837 |
if (msg != ERR_PTR(-EAGAIN)) |
1da177e4c
|
838 839 840 841 842 843 844 845 846 847 848 |
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)) |
5a06a363e
|
849 |
return PTR_ERR(msg); |
1da177e4c
|
850 851 |
msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz; |
651971cb7
|
852 853 |
*pmtype = msg->m_type; if (store_msg(mtext, msg, msgsz)) |
5a06a363e
|
854 |
msgsz = -EFAULT; |
651971cb7
|
855 |
|
1da177e4c
|
856 |
free_msg(msg); |
5a06a363e
|
857 |
|
1da177e4c
|
858 859 |
return msgsz; } |
651971cb7
|
860 861 862 863 864 865 866 867 868 869 870 871 872 873 |
asmlinkage long sys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz, long msgtyp, int msgflg) { long err, mtype; err = do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg); if (err < 0) goto out; if (put_user(mtype, &msgp->mtype)) err = -EFAULT; out: return err; } |
1da177e4c
|
874 |
#ifdef CONFIG_PROC_FS |
19b4946ca
|
875 |
static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
1da177e4c
|
876 |
{ |
19b4946ca
|
877 878 879 |
struct msg_queue *msq = it; return seq_printf(s, |
5a06a363e
|
880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 |
"%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu ", 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); |
1da177e4c
|
896 897 |
} #endif |