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android / kernel / common / eadde287a62e6 / . / ipc / msg.c
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// SPDX-License-Identifier: GPL-2.0
/*
* linux/ipc/msg.c
* Copyright (C) 1992 Krishna Balasubramanian
*
* Removed all the remaining kerneld mess
* Catch the -EFAULT stuff properly
* Use GFP_KERNEL for messages as in 1.2
* Fixed up the unchecked user space derefs
* Copyright (C) 1998 Alan Cox & Andi Kleen
*
* /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
*
* mostly rewritten, threaded and wake-one semantics added
* MSGMAX limit removed, sysctl's added
* (c) 1999 Manfred Spraul <manfred@colorfullife.com>
*
* support for audit of ipc object properties and permission changes
* Dustin Kirkland <dustin.kirkland@us.ibm.com>
*
* namespaces support
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <xemul@openvz.org>
*/
#include <linux/capability.h>
#include <linux/msg.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/security.h>
#include <linux/sched/wake_q.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/seq_file.h>
#include <linux/rwsem.h>
#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>
#include <linux/rhashtable.h>
#include <asm/current.h>
#include <linux/uaccess.h>
#include "util.h"
/* one msq_queue structure for each present queue on the system */
struct msg_queue {
struct kern_ipc_perm q_perm;
time64_t q_stime; /* last msgsnd time */
time64_t q_rtime; /* last msgrcv time */
time64_t q_ctime; /* last change time */
unsigned long q_cbytes; /* current number of bytes on queue */
unsigned long q_qnum; /* number of messages in queue */
unsigned long q_qbytes; /* max number of bytes on queue */
struct pid *q_lspid; /* pid of last msgsnd */
struct pid *q_lrpid; /* last receive pid */
struct list_head q_messages;
struct list_head q_receivers;
struct list_head q_senders;
} __randomize_layout;
/*
* MSG_BARRIER Locking:
*
* Similar to the optimization used in ipc/mqueue.c, one syscall return path
* does not acquire any locks when it sees that a message exists in
* msg_receiver.r_msg. Therefore r_msg is set using smp_store_release()
* and accessed using READ_ONCE()+smp_acquire__after_ctrl_dep(). In addition,
* wake_q_add_safe() is used. See ipc/mqueue.c for more details
*/
/* one msg_receiver structure for each sleeping receiver */
struct msg_receiver {
struct list_head r_list;
struct task_struct *r_tsk;
int r_mode;
long r_msgtype;
long r_maxsize;
struct msg_msg *r_msg;
};
/* one msg_sender for each sleeping sender */
struct msg_sender {
struct list_head list;
struct task_struct *tsk;
size_t msgsz;
};
#define SEARCH_ANY 1
#define SEARCH_EQUAL 2
#define SEARCH_NOTEQUAL 3
#define SEARCH_LESSEQUAL 4
#define SEARCH_NUMBER 5
#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
if (IS_ERR(ipcp))
return ERR_CAST(ipcp);
return container_of(ipcp, struct msg_queue, q_perm);
}
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 kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
security_msg_queue_free(&msq->q_perm);
kvfree(msq);
}
/**
* newque - Create a new msg queue
* @ns: namespace
* @params: ptr to the structure that contains the key and msgflg
*
* Called with msg_ids.rwsem held (writer)
*/
static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
struct msg_queue *msq;
int retval;
key_t key = params->key;
int msgflg = params->flg;
msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
if (unlikely(!msq))
return -ENOMEM;
msq->q_perm.mode = msgflg & S_IRWXUGO;
msq->q_perm.key = key;
msq->q_perm.security = NULL;
retval = security_msg_queue_alloc(&msq->q_perm);
if (retval) {
kvfree(msq);
return retval;
}
msq->q_stime = msq->q_rtime = 0;
msq->q_ctime = ktime_get_real_seconds();
msq->q_cbytes = msq->q_qnum = 0;
msq->q_qbytes = ns->msg_ctlmnb;
msq->q_lspid = msq->q_lrpid = NULL;
INIT_LIST_HEAD(&msq->q_messages);
INIT_LIST_HEAD(&msq->q_receivers);
INIT_LIST_HEAD(&msq->q_senders);
/* ipc_addid() locks msq upon success. */
retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
if (retval < 0) {
ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
return retval;
}
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
return msq->q_perm.id;
}
static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
{
return msgsz + msq->q_cbytes <= msq->q_qbytes &&
1 + msq->q_qnum <= msq->q_qbytes;
}
static inline void ss_add(struct msg_queue *msq,
struct msg_sender *mss, size_t msgsz)
{
mss->tsk = current;
mss->msgsz = msgsz;
/*
* No memory barrier required: we did ipc_lock_object(),
* and the waker obtains that lock before calling wake_q_add().
*/
__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)
list_del(&mss->list);
}
static void ss_wakeup(struct msg_queue *msq,
struct wake_q_head *wake_q, bool kill)
{
struct msg_sender *mss, *t;
struct task_struct *stop_tsk = NULL;
struct list_head *h = &msq->q_senders;
list_for_each_entry_safe(mss, t, h, list) {
if (kill)
mss->list.next = NULL;
/*
* Stop at the first task we don't wakeup,
* we've already iterated the original
* sender queue.
*/
else if (stop_tsk == mss->tsk)
break;
/*
* We are not in an EIDRM scenario here, therefore
* verify that we really need to wakeup the task.
* To maintain current semantics and wakeup order,
* move the sender to the tail on behalf of the
* blocked task.
*/
else if (!msg_fits_inqueue(msq, mss->msgsz)) {
if (!stop_tsk)
stop_tsk = mss->tsk;
list_move_tail(&mss->list, &msq->q_senders);
continue;
}
wake_q_add(wake_q, mss->tsk);
}
}
static void expunge_all(struct msg_queue *msq, int res,
struct wake_q_head *wake_q)
{
struct msg_receiver *msr, *t;
list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
struct task_struct *r_tsk;
r_tsk = get_task_struct(msr->r_tsk);
/* see MSG_BARRIER for purpose/pairing */
smp_store_release(&msr->r_msg, ERR_PTR(res));
wake_q_add_safe(wake_q, r_tsk);
}
}
/*
* 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)
__releases(RCU)
__releases(&msq->q_perm)
{
struct msg_msg *msg, *t;
struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
DEFINE_WAKE_Q(wake_q);
expunge_all(msq, -EIDRM, &wake_q);
ss_wakeup(msq, &wake_q, true);
msg_rmid(ns, msq);
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
rcu_read_unlock();
list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
atomic_dec(&ns->msg_hdrs);
free_msg(msg);
}
atomic_sub(msq->q_cbytes, &ns->msg_bytes);
ipc_update_pid(&msq->q_lspid, NULL);
ipc_update_pid(&msq->q_lrpid, NULL);
ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
}
long ksys_msgget(key_t key, int msgflg)
{
struct ipc_namespace *ns;
static const struct ipc_ops msg_ops = {
.getnew = newque,
.associate = security_msg_queue_associate,
};
struct ipc_params msg_params;
ns = current->nsproxy->ipc_ns;
msg_params.key = key;
msg_params.flg = msgflg;
return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
}
SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
{
return ksys_msgget(key, msgflg);
}
static inline unsigned long
copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
switch (version) {
case IPC_64:
return copy_to_user(buf, in, sizeof(*in));
case IPC_OLD:
{
struct msqid_ds out;
memset(&out, 0, sizeof(out));
ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
out.msg_stime = in->msg_stime;
out.msg_rtime = in->msg_rtime;
out.msg_ctime = in->msg_ctime;
if (in->msg_cbytes > USHRT_MAX)
out.msg_cbytes = USHRT_MAX;
else
out.msg_cbytes = in->msg_cbytes;
out.msg_lcbytes = in->msg_cbytes;
if (in->msg_qnum > USHRT_MAX)
out.msg_qnum = USHRT_MAX;
else
out.msg_qnum = in->msg_qnum;
if (in->msg_qbytes > USHRT_MAX)
out.msg_qbytes = USHRT_MAX;
else
out.msg_qbytes = in->msg_qbytes;
out.msg_lqbytes = in->msg_qbytes;
out.msg_lspid = in->msg_lspid;
out.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &out, sizeof(out));
}
default:
return -EINVAL;
}
}
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 ipc64_perm *perm, int msg_qbytes)
{
struct kern_ipc_perm *ipcp;
struct msg_queue *msq;
int err;
down_write(&msg_ids(ns).rwsem);
rcu_read_lock();
ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
perm, msg_qbytes);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
goto out_unlock1;
}
msq = container_of(ipcp, struct msg_queue, q_perm);
err = security_msg_queue_msgctl(&msq->q_perm, cmd);
if (err)
goto out_unlock1;
switch (cmd) {
case IPC_RMID:
ipc_lock_object(&msq->q_perm);
/* freeque unlocks the ipc object and rcu */
freeque(ns, ipcp);
goto out_up;
case IPC_SET:
{
DEFINE_WAKE_Q(wake_q);
if (msg_qbytes > ns->msg_ctlmnb &&
!capable(CAP_SYS_RESOURCE)) {
err = -EPERM;
goto out_unlock1;
}
ipc_lock_object(&msq->q_perm);
err = ipc_update_perm(perm, ipcp);
if (err)
goto out_unlock0;
msq->q_qbytes = msg_qbytes;
msq->q_ctime = ktime_get_real_seconds();
/*
* Sleeping receivers might be excluded by
* stricter permissions.
*/
expunge_all(msq, -EAGAIN, &wake_q);
/*
* Sleeping senders might be able to send
* due to a larger queue size.
*/
ss_wakeup(msq, &wake_q, false);
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
goto out_unlock1;
}
default:
err = -EINVAL;
goto out_unlock1;
}
out_unlock0:
ipc_unlock_object(&msq->q_perm);
out_unlock1:
rcu_read_unlock();
out_up:
up_write(&msg_ids(ns).rwsem);
return err;
}
static int msgctl_info(struct ipc_namespace *ns, int msqid,
int cmd, struct msginfo *msginfo)
{
int err;
int max_idx;
/*
* 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_idx = ipc_get_maxidx(&msg_ids(ns));
up_read(&msg_ids(ns).rwsem);
return (max_idx < 0) ? 0 : max_idx;
}
static int msgctl_stat(struct ipc_namespace *ns, int msqid,
int cmd, struct msqid64_ds *p)
{
struct msg_queue *msq;
int err;
memset(p, 0, sizeof(*p));
rcu_read_lock();
if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
msq = msq_obtain_object(ns, msqid);
if (IS_ERR(msq)) {
err = PTR_ERR(msq);
goto out_unlock;
}
} else { /* IPC_STAT */
msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) {
err = PTR_ERR(msq);
goto out_unlock;
}
}
/* see comment for SHM_STAT_ANY */
if (cmd == MSG_STAT_ANY)
audit_ipc_obj(&msq->q_perm);
else {
err = -EACCES;
if (ipcperms(ns, &msq->q_perm, S_IRUGO))
goto out_unlock;
}
err = security_msg_queue_msgctl(&msq->q_perm, cmd);
if (err)
goto out_unlock;
ipc_lock_object(&msq->q_perm);
if (!ipc_valid_object(&msq->q_perm)) {
ipc_unlock_object(&msq->q_perm);
err = -EIDRM;
goto out_unlock;
}
kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
p->msg_stime = msq->q_stime;
p->msg_rtime = msq->q_rtime;
p->msg_ctime = msq->q_ctime;
#ifndef CONFIG_64BIT
p->msg_stime_high = msq->q_stime >> 32;
p->msg_rtime_high = msq->q_rtime >> 32;
p->msg_ctime_high = msq->q_ctime >> 32;
#endif
p->msg_cbytes = msq->q_cbytes;
p->msg_qnum = msq->q_qnum;
p->msg_qbytes = msq->q_qbytes;
p->msg_lspid = pid_vnr(msq->q_lspid);
p->msg_lrpid = pid_vnr(msq->q_lrpid);
if (cmd == IPC_STAT) {
/*
* As defined in SUS:
* Return 0 on success
*/
err = 0;
} else {
/*
* MSG_STAT and MSG_STAT_ANY (both Linux specific)
* Return the full id, including the sequence number
*/
err = msq->q_perm.id;
}
ipc_unlock_object(&msq->q_perm);
out_unlock:
rcu_read_unlock();
return err;
}
static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version)
{
struct ipc_namespace *ns;
struct msqid64_ds msqid64;
int err;
if (msqid < 0 || cmd < 0)
return -EINVAL;
ns = current->nsproxy->ipc_ns;
switch (cmd) {
case IPC_INFO:
case MSG_INFO: {
struct msginfo msginfo;
err = msgctl_info(ns, msqid, cmd, &msginfo);
if (err < 0)
return err;
if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
err = -EFAULT;
return err;
}
case MSG_STAT: /* msqid is an index rather than a msg queue id */
case MSG_STAT_ANY:
case IPC_STAT:
err = msgctl_stat(ns, msqid, cmd, &msqid64);
if (err < 0)
return err;
if (copy_msqid_to_user(buf, &msqid64, version))
err = -EFAULT;
return err;
case IPC_SET:
if (copy_msqid_from_user(&msqid64, buf, version))
return -EFAULT;
return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm,
msqid64.msg_qbytes);
case IPC_RMID:
return msgctl_down(ns, msqid, cmd, NULL, 0);
default:
return -EINVAL;
}
}
SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
{
return ksys_msgctl(msqid, cmd, buf, IPC_64);
}
#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
{
int version = ipc_parse_version(&cmd);
return ksys_msgctl(msqid, cmd, buf, version);
}
SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
{
return ksys_old_msgctl(msqid, cmd, buf);
}
#endif
#ifdef CONFIG_COMPAT
struct compat_msqid_ds {
struct compat_ipc_perm msg_perm;
compat_uptr_t msg_first;
compat_uptr_t msg_last;
old_time32_t msg_stime;
old_time32_t msg_rtime;
old_time32_t msg_ctime;
compat_ulong_t msg_lcbytes;
compat_ulong_t msg_lqbytes;
unsigned short msg_cbytes;
unsigned short msg_qnum;
unsigned short msg_qbytes;
compat_ipc_pid_t msg_lspid;
compat_ipc_pid_t msg_lrpid;
};
static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
int version)
{
memset(out, 0, sizeof(*out));
if (version == IPC_64) {
struct compat_msqid64_ds __user *p = buf;
if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
return -EFAULT;
if (get_user(out->msg_qbytes, &p->msg_qbytes))
return -EFAULT;
} else {
struct compat_msqid_ds __user *p = buf;
if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
return -EFAULT;
if (get_user(out->msg_qbytes, &p->msg_qbytes))
return -EFAULT;
}
return 0;
}
static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
int version)
{
if (version == IPC_64) {
struct compat_msqid64_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
v.msg_stime = lower_32_bits(in->msg_stime);
v.msg_stime_high = upper_32_bits(in->msg_stime);
v.msg_rtime = lower_32_bits(in->msg_rtime);
v.msg_rtime_high = upper_32_bits(in->msg_rtime);
v.msg_ctime = lower_32_bits(in->msg_ctime);
v.msg_ctime_high = upper_32_bits(in->msg_ctime);
v.msg_cbytes = in->msg_cbytes;
v.msg_qnum = in->msg_qnum;
v.msg_qbytes = in->msg_qbytes;
v.msg_lspid = in->msg_lspid;
v.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &v, sizeof(v));
} else {
struct compat_msqid_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
v.msg_stime = in->msg_stime;
v.msg_rtime = in->msg_rtime;
v.msg_ctime = in->msg_ctime;
v.msg_cbytes = in->msg_cbytes;
v.msg_qnum = in->msg_qnum;
v.msg_qbytes = in->msg_qbytes;
v.msg_lspid = in->msg_lspid;
v.msg_lrpid = in->msg_lrpid;
return copy_to_user(buf, &v, sizeof(v));
}
}
static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version)
{
struct ipc_namespace *ns;
int err;
struct msqid64_ds msqid64;
ns = current->nsproxy->ipc_ns;
if (msqid < 0 || cmd < 0)
return -EINVAL;
switch (cmd & (~IPC_64)) {
case IPC_INFO:
case MSG_INFO: {
struct msginfo msginfo;
err = msgctl_info(ns, msqid, cmd, &msginfo);
if (err < 0)
return err;
if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
err = -EFAULT;
return err;
}
case IPC_STAT:
case MSG_STAT:
case MSG_STAT_ANY:
err = msgctl_stat(ns, msqid, cmd, &msqid64);
if (err < 0)
return err;
if (copy_compat_msqid_to_user(uptr, &msqid64, version))
err = -EFAULT;
return err;
case IPC_SET:
if (copy_compat_msqid_from_user(&msqid64, uptr, version))
return -EFAULT;
return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes);
case IPC_RMID:
return msgctl_down(ns, msqid, cmd, NULL, 0);
default:
return -EINVAL;
}
}
COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
{
return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64);
}
#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr)
{
int version = compat_ipc_parse_version(&cmd);
return compat_ksys_msgctl(msqid, cmd, uptr, version);
}
COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr)
{
return compat_ksys_old_msgctl(msqid, cmd, uptr);
}
#endif
#endif
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 wake_q_head *wake_q)
{
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->q_perm, msg, msr->r_tsk,
msr->r_msgtype, msr->r_mode)) {
list_del(&msr->r_list);
if (msr->r_maxsize < msg->m_ts) {
wake_q_add(wake_q, msr->r_tsk);
/* See expunge_all regarding memory barrier */
smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG));
} else {
ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
msq->q_rtime = ktime_get_real_seconds();
wake_q_add(wake_q, msr->r_tsk);
/* See expunge_all regarding memory barrier */
smp_store_release(&msr->r_msg, msg);
return 1;
}
}
}
return 0;
}
static 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;
DEFINE_WAKE_Q(wake_q);
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->q_perm, msg, msgflg);
if (err)
goto out_unlock0;
if (msg_fits_inqueue(msq, msgsz))
break;
/* queue full, wait: */
if (msgflg & IPC_NOWAIT) {
err = -EAGAIN;
goto out_unlock0;
}
/* enqueue the sender and prepare to block */
ss_add(msq, &s, msgsz);
if (!ipc_rcu_getref(&msq->q_perm)) {
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->q_perm, msg_rcu_free);
/* raced with RMID? */
if (!ipc_valid_object(&msq->q_perm)) {
err = -EIDRM;
goto out_unlock0;
}
ss_del(&s);
if (signal_pending(current)) {
err = -ERESTARTNOHAND;
goto out_unlock0;
}
}
ipc_update_pid(&msq->q_lspid, task_tgid(current));
msq->q_stime = ktime_get_real_seconds();
if (!pipelined_send(msq, msg, &wake_q)) {
/* 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);
wake_up_q(&wake_q);
out_unlock1:
rcu_read_unlock();
if (msg != NULL)
free_msg(msg);
return err;
}
long ksys_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);
}
SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
int, msgflg)
{
return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
}
#ifdef CONFIG_COMPAT
struct compat_msgbuf {
compat_long_t mtype;
char mtext[1];
};
long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
compat_ssize_t msgsz, int msgflg)
{
struct compat_msgbuf __user *up = compat_ptr(msgp);
compat_long_t mtype;
if (get_user(mtype, &up->mtype))
return -EFAULT;
return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
}
COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, int, msgflg)
{
return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
}
#endif
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) {
if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
*msgtyp = LONG_MAX;
else
*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->q_perm, 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);
}
static 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;
DEFINE_WAKE_Q(wake_q);
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 = ktime_get_real_seconds();
ipc_update_pid(&msq->q_lrpid, task_tgid(current));
msq->q_cbytes -= msg->m_ts;
atomic_sub(msg->m_ts, &ns->msg_bytes);
atomic_dec(&ns->msg_hdrs);
ss_wakeup(msq, &wake_q, false);
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;
/* memory barrier not require due to ipc_lock_object() */
WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN));
/* memory barrier not required, we own ipc_lock_object() */
__set_current_state(TASK_INTERRUPTIBLE);
ipc_unlock_object(&msq->q_perm);
rcu_read_unlock();
schedule();
/*
* Lockless receive, part 1:
* 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();
/*
* Lockless receive, part 2:
* The work in pipelined_send() and expunge_all():
* - Set pointer to message
* - Queue the receiver task for later wakeup
* - Wake up the process after the lock is dropped.
*
* Should the process wake up before this wakeup (due to a
* signal) it will either see the message and continue ...
*/
msg = READ_ONCE(msr_d.r_msg);
if (msg != ERR_PTR(-EAGAIN)) {
/* see MSG_BARRIER for purpose/pairing */
smp_acquire__after_ctrl_dep();
goto out_unlock1;
}
/*
* ... or see -EAGAIN, acquire the lock to check the message
* again.
*/
ipc_lock_object(&msq->q_perm);
msg = READ_ONCE(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);
wake_up_q(&wake_q);
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;
}
long ksys_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);
}
SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
long, msgtyp, int, msgflg)
{
return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#ifdef CONFIG_COMPAT
static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
{
struct compat_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;
}
long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
compat_long_t msgtyp, int msgflg)
{
return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
msgflg, compat_do_msg_fill);
}
COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, compat_long_t, msgtyp,
int, msgflg)
{
return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#endif
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);
rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
}
#endif
#ifdef CONFIG_PROC_FS
static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
{
struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
struct user_namespace *user_ns = seq_user_ns(s);
struct kern_ipc_perm *ipcp = it;
struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
seq_printf(s,
"%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
msq->q_perm.key,
msq->q_perm.id,
msq->q_perm.mode,
msq->q_cbytes,
msq->q_qnum,
pid_nr_ns(msq->q_lspid, pid_ns),
pid_nr_ns(msq->q_lrpid, pid_ns),
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);
}