--- /dev/null
+/*
+ * linux/ipc/msg.c
+ * Copyright (C) 1992 Krishna Balasubramanian
+ *
+ * Removed all the remaining kerneld mess
+ * Catch the -EFAULT stuff properly
+ * Use GFP_KERNEL for messages as in 1.2
+ * Fixed up the unchecked user space derefs
+ * Copyright (C) 1998 Alan Cox & Andi Kleen
+ *
+ * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
+ *
+ * mostly rewritten, threaded and wake-one semantics added
+ * MSGMAX limit removed, sysctl's added
+ * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
+ *
+ * support for audit of ipc object properties and permission changes
+ * Dustin Kirkland <dustin.kirkland@us.ibm.com>
+ *
+ * namespaces support
+ * OpenVZ, SWsoft Inc.
+ * Pavel Emelianov <xemul@openvz.org>
+ */
+
+#include <linux/capability.h>
+#include <linux/msg.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/proc_fs.h>
+#include <linux/list.h>
+#include <linux/security.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <linux/seq_file.h>
+#include <linux/rwsem.h>
+#include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
+
+#include <asm/current.h>
+#include <linux/uaccess.h>
+#include "util.h"
+
+/* one msg_receiver structure for each sleeping receiver */
+struct msg_receiver {
+ struct list_head r_list;
+ struct task_struct *r_tsk;
+
+ int r_mode;
+ long r_msgtype;
+ long r_maxsize;
+
+ /*
+ * Mark r_msg volatile so that the compiler
+ * does not try to get smart and optimize
+ * it. We rely on this for the lockless
+ * receive algorithm.
+ */
+ struct msg_msg *volatile r_msg;
+};
+
+/* one msg_sender for each sleeping sender */
+struct msg_sender {
+ struct list_head list;
+ struct task_struct *tsk;
+};
+
+#define SEARCH_ANY 1
+#define SEARCH_EQUAL 2
+#define SEARCH_NOTEQUAL 3
+#define SEARCH_LESSEQUAL 4
+#define SEARCH_NUMBER 5
+
+#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
+
+static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
+
+ if (IS_ERR(ipcp))
+ return ERR_CAST(ipcp);
+
+ return container_of(ipcp, struct msg_queue, q_perm);
+}
+
+static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
+ int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
+
+ if (IS_ERR(ipcp))
+ return ERR_CAST(ipcp);
+
+ return container_of(ipcp, struct msg_queue, q_perm);
+}
+
+static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
+{
+ ipc_rmid(&msg_ids(ns), &s->q_perm);
+}
+
+static void msg_rcu_free(struct rcu_head *head)
+{
+ struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
+ struct msg_queue *msq = ipc_rcu_to_struct(p);
+
+ security_msg_queue_free(msq);
+ ipc_rcu_free(head);
+}
+
+/**
+ * newque - Create a new msg queue
+ * @ns: namespace
+ * @params: ptr to the structure that contains the key and msgflg
+ *
+ * Called with msg_ids.rwsem held (writer)
+ */
+static int newque(struct ipc_namespace *ns, struct ipc_params *params)
+{
+ struct msg_queue *msq;
+ int id, retval;
+ key_t key = params->key;
+ int msgflg = params->flg;
+
+ msq = ipc_rcu_alloc(sizeof(*msq));
+ if (!msq)
+ return -ENOMEM;
+
+ msq->q_perm.mode = msgflg & S_IRWXUGO;
+ msq->q_perm.key = key;
+
+ msq->q_perm.security = NULL;
+ retval = security_msg_queue_alloc(msq);
+ if (retval) {
+ ipc_rcu_putref(msq, ipc_rcu_free);
+ return retval;
+ }
+
+ /* ipc_addid() locks msq upon success. */
+ id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
+ if (id < 0) {
+ ipc_rcu_putref(msq, msg_rcu_free);
+ return id;
+ }
+
+ msq->q_stime = msq->q_rtime = 0;
+ msq->q_ctime = get_seconds();
+ msq->q_cbytes = msq->q_qnum = 0;
+ msq->q_qbytes = ns->msg_ctlmnb;
+ msq->q_lspid = msq->q_lrpid = 0;
+ INIT_LIST_HEAD(&msq->q_messages);
+ INIT_LIST_HEAD(&msq->q_receivers);
+ INIT_LIST_HEAD(&msq->q_senders);
+
+ ipc_unlock_object(&msq->q_perm);
+ rcu_read_unlock();
+
+ return msq->q_perm.id;
+}
+
+static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
+{
+ mss->tsk = current;
+ __set_current_state(TASK_INTERRUPTIBLE);
+ list_add_tail(&mss->list, &msq->q_senders);
+}
+
+static inline void ss_del(struct msg_sender *mss)
+{
+ if (mss->list.next != NULL)
+ list_del(&mss->list);
+}
+
+static void ss_wakeup(struct list_head *h, int kill)
+{
+ struct msg_sender *mss, *t;
+
+ list_for_each_entry_safe(mss, t, h, list) {
+ if (kill)
+ mss->list.next = NULL;
+ wake_up_process(mss->tsk);
+ }
+}
+
+static void expunge_all(struct msg_queue *msq, int res)
+{
+ struct msg_receiver *msr, *t;
+
+ list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
+ /*
+ * Make sure that the wakeup doesnt preempt
+ * this CPU prematurely. (on PREEMPT_RT)
+ */
+ preempt_disable_rt();
+
+ msr->r_msg = NULL; /* initialize expunge ordering */
+ wake_up_process(msr->r_tsk);
+ /*
+ * Ensure that the wakeup is visible before setting r_msg as
+ * the receiving end depends on it: either spinning on a nil,
+ * or dealing with -EAGAIN cases. See lockless receive part 1
+ * and 2 in do_msgrcv().
+ */
+ smp_mb();
+ msr->r_msg = ERR_PTR(res);
+
+ preempt_enable_rt();
+ }
+}
+
+/*
+ * freeque() wakes up waiters on the sender and receiver waiting queue,
+ * removes the message queue from message queue ID IDR, and cleans up all the
+ * messages associated with this queue.
+ *
+ * msg_ids.rwsem (writer) and the spinlock for this message queue are held
+ * before freeque() is called. msg_ids.rwsem remains locked on exit.
+ */
+static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
+{
+ struct msg_msg *msg, *t;
+ struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
+
+ expunge_all(msq, -EIDRM);
+ ss_wakeup(&msq->q_senders, 1);
+ msg_rmid(ns, msq);
+ ipc_unlock_object(&msq->q_perm);
+ rcu_read_unlock();
+
+ list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
+ atomic_dec(&ns->msg_hdrs);
+ free_msg(msg);
+ }
+ atomic_sub(msq->q_cbytes, &ns->msg_bytes);
+ ipc_rcu_putref(msq, msg_rcu_free);
+}
+
+/*
+ * Called with msg_ids.rwsem and ipcp locked.
+ */
+static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
+{
+ struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
+
+ return security_msg_queue_associate(msq, msgflg);
+}
+
+SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
+{
+ struct ipc_namespace *ns;
+ static const struct ipc_ops msg_ops = {
+ .getnew = newque,
+ .associate = msg_security,
+ };
+ struct ipc_params msg_params;
+
+ ns = current->nsproxy->ipc_ns;
+
+ msg_params.key = key;
+ msg_params.flg = msgflg;
+
+ return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
+}
+
+static inline unsigned long
+copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
+{
+ switch (version) {
+ case IPC_64:
+ return copy_to_user(buf, in, sizeof(*in));
+ case IPC_OLD:
+ {
+ struct msqid_ds out;
+
+ memset(&out, 0, sizeof(out));
+
+ ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
+
+ out.msg_stime = in->msg_stime;
+ out.msg_rtime = in->msg_rtime;
+ out.msg_ctime = in->msg_ctime;
+
+ if (in->msg_cbytes > USHRT_MAX)
+ out.msg_cbytes = USHRT_MAX;
+ else
+ out.msg_cbytes = in->msg_cbytes;
+ out.msg_lcbytes = in->msg_cbytes;
+
+ if (in->msg_qnum > USHRT_MAX)
+ out.msg_qnum = USHRT_MAX;
+ else
+ out.msg_qnum = in->msg_qnum;
+
+ if (in->msg_qbytes > USHRT_MAX)
+ out.msg_qbytes = USHRT_MAX;
+ else
+ out.msg_qbytes = in->msg_qbytes;
+ out.msg_lqbytes = in->msg_qbytes;
+
+ out.msg_lspid = in->msg_lspid;
+ out.msg_lrpid = in->msg_lrpid;
+
+ return copy_to_user(buf, &out, sizeof(out));
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static inline unsigned long
+copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
+{
+ switch (version) {
+ case IPC_64:
+ if (copy_from_user(out, buf, sizeof(*out)))
+ return -EFAULT;
+ return 0;
+ case IPC_OLD:
+ {
+ struct msqid_ds tbuf_old;
+
+ if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
+ return -EFAULT;
+
+ out->msg_perm.uid = tbuf_old.msg_perm.uid;
+ out->msg_perm.gid = tbuf_old.msg_perm.gid;
+ out->msg_perm.mode = tbuf_old.msg_perm.mode;
+
+ if (tbuf_old.msg_qbytes == 0)
+ out->msg_qbytes = tbuf_old.msg_lqbytes;
+ else
+ out->msg_qbytes = tbuf_old.msg_qbytes;
+
+ return 0;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * This function handles some msgctl commands which require the rwsem
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rwsem is taken inside this function.
+ */
+static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
+ struct msqid_ds __user *buf, int version)
+{
+ struct kern_ipc_perm *ipcp;
+ struct msqid64_ds uninitialized_var(msqid64);
+ struct msg_queue *msq;
+ int err;
+
+ if (cmd == IPC_SET) {
+ if (copy_msqid_from_user(&msqid64, buf, version))
+ return -EFAULT;
+ }
+
+ down_write(&msg_ids(ns).rwsem);
+ rcu_read_lock();
+
+ ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
+ &msqid64.msg_perm, msqid64.msg_qbytes);
+ if (IS_ERR(ipcp)) {
+ err = PTR_ERR(ipcp);
+ goto out_unlock1;
+ }
+
+ msq = container_of(ipcp, struct msg_queue, q_perm);
+
+ err = security_msg_queue_msgctl(msq, cmd);
+ if (err)
+ goto out_unlock1;
+
+ switch (cmd) {
+ case IPC_RMID:
+ ipc_lock_object(&msq->q_perm);
+ /* freeque unlocks the ipc object and rcu */
+ freeque(ns, ipcp);
+ goto out_up;
+ case IPC_SET:
+ if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
+ !capable(CAP_SYS_RESOURCE)) {
+ err = -EPERM;
+ goto out_unlock1;
+ }
+
+ ipc_lock_object(&msq->q_perm);
+ err = ipc_update_perm(&msqid64.msg_perm, ipcp);
+ if (err)
+ goto out_unlock0;
+
+ msq->q_qbytes = msqid64.msg_qbytes;
+
+ msq->q_ctime = get_seconds();
+ /* sleeping receivers might be excluded by
+ * stricter permissions.
+ */
+ expunge_all(msq, -EAGAIN);
+ /* sleeping senders might be able to send
+ * due to a larger queue size.
+ */
+ ss_wakeup(&msq->q_senders, 0);
+ break;
+ default:
+ err = -EINVAL;
+ goto out_unlock1;
+ }
+
+out_unlock0:
+ ipc_unlock_object(&msq->q_perm);
+out_unlock1:
+ rcu_read_unlock();
+out_up:
+ up_write(&msg_ids(ns).rwsem);
+ return err;
+}
+
+static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
+ int cmd, int version, void __user *buf)
+{
+ int err;
+ struct msg_queue *msq;
+
+ switch (cmd) {
+ case IPC_INFO:
+ case MSG_INFO:
+ {
+ struct msginfo msginfo;
+ int max_id;
+
+ if (!buf)
+ return -EFAULT;
+
+ /*
+ * We must not return kernel stack data.
+ * due to padding, it's not enough
+ * to set all member fields.
+ */
+ err = security_msg_queue_msgctl(NULL, cmd);
+ if (err)
+ return err;
+
+ memset(&msginfo, 0, sizeof(msginfo));
+ msginfo.msgmni = ns->msg_ctlmni;
+ msginfo.msgmax = ns->msg_ctlmax;
+ msginfo.msgmnb = ns->msg_ctlmnb;
+ msginfo.msgssz = MSGSSZ;
+ msginfo.msgseg = MSGSEG;
+ down_read(&msg_ids(ns).rwsem);
+ if (cmd == MSG_INFO) {
+ msginfo.msgpool = msg_ids(ns).in_use;
+ msginfo.msgmap = atomic_read(&ns->msg_hdrs);
+ msginfo.msgtql = atomic_read(&ns->msg_bytes);
+ } else {
+ msginfo.msgmap = MSGMAP;
+ msginfo.msgpool = MSGPOOL;
+ msginfo.msgtql = MSGTQL;
+ }
+ max_id = ipc_get_maxid(&msg_ids(ns));
+ up_read(&msg_ids(ns).rwsem);
+ if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
+ return -EFAULT;
+ return (max_id < 0) ? 0 : max_id;
+ }
+
+ case MSG_STAT:
+ case IPC_STAT:
+ {
+ struct msqid64_ds tbuf;
+ int success_return;
+
+ if (!buf)
+ return -EFAULT;
+
+ memset(&tbuf, 0, sizeof(tbuf));
+
+ rcu_read_lock();
+ if (cmd == MSG_STAT) {
+ msq = msq_obtain_object(ns, msqid);
+ if (IS_ERR(msq)) {
+ err = PTR_ERR(msq);
+ goto out_unlock;
+ }
+ success_return = msq->q_perm.id;
+ } else {
+ msq = msq_obtain_object_check(ns, msqid);
+ if (IS_ERR(msq)) {
+ err = PTR_ERR(msq);
+ goto out_unlock;
+ }
+ success_return = 0;
+ }
+
+ err = -EACCES;
+ if (ipcperms(ns, &msq->q_perm, S_IRUGO))
+ goto out_unlock;
+
+ err = security_msg_queue_msgctl(msq, cmd);
+ if (err)
+ goto out_unlock;
+
+ kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
+ tbuf.msg_stime = msq->q_stime;
+ tbuf.msg_rtime = msq->q_rtime;
+ tbuf.msg_ctime = msq->q_ctime;
+ tbuf.msg_cbytes = msq->q_cbytes;
+ tbuf.msg_qnum = msq->q_qnum;
+ tbuf.msg_qbytes = msq->q_qbytes;
+ tbuf.msg_lspid = msq->q_lspid;
+ tbuf.msg_lrpid = msq->q_lrpid;
+ rcu_read_unlock();
+
+ if (copy_msqid_to_user(buf, &tbuf, version))
+ return -EFAULT;
+ return success_return;
+ }
+
+ default:
+ return -EINVAL;
+ }
+
+ return err;
+out_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
+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)) {
+ /*
+ * Make sure that the wakeup doesnt preempt
+ * this CPU prematurely. (on PREEMPT_RT)
+ */
+ preempt_disable_rt();
+
+ 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);
+ smp_mb(); /* see barrier comment below */
+ 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 end depends
+ * on it. See lockless receive part 1 and 2 in
+ * do_msgrcv().
+ */
+ smp_mb();
+ msr->r_msg = msg;
+ preempt_enable_rt();
+
+ return 1;
+ }
+ preempt_enable_rt();
+ }
+ }
+ 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, ipc_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.
+ */
+ 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))
+ 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);
+}
Code Review / kvmfornfv.git / blobdiff