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|
/* $OpenBSD: sysv_msg.c,v 1.37 2020/06/24 22:03:42 cheloha Exp $ */
/* $NetBSD: sysv_msg.c,v 1.19 1996/02/09 19:00:18 christos Exp $ */
/*
* Copyright (c) 2009 Bret S. Lambert <blambert@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Implementation of SVID messages
*
* Author: Daniel Boulet
*
* Copyright 1993 Daniel Boulet and RTMX Inc.
*
* This system call was implemented by Daniel Boulet under contract from RTMX.
*
* Redistribution and use in source forms, with and without modification,
* are permitted provided that this entire comment appears intact.
*
* Redistribution in binary form may occur without any restrictions.
* Obviously, it would be nice if you gave credit where credit is due
* but requiring it would be too onerous.
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mount.h>
#include <sys/msg.h>
#include <sys/pool.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/syscallargs.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/uio.h>
struct que *que_create(key_t, struct ucred *, int);
struct que *que_lookup(int);
struct que *que_key_lookup(key_t);
void que_wakewriters(void);
void que_free(struct que *);
struct msg *msg_create(struct que *);
void msg_free(struct msg *);
void msg_enqueue(struct que *, struct msg *, struct proc *);
void msg_dequeue(struct que *, struct msg *, struct proc *);
struct msg *msg_lookup(struct que *, int);
int msg_copyin(struct msg *, const char *, size_t, struct proc *);
int msg_copyout(struct msg *, char *, size_t *, struct proc *);
struct pool sysvmsgpl;
struct msginfo msginfo;
TAILQ_HEAD(, que) msg_queues;
int num_ques;
int num_msgs;
int sequence;
int maxmsgs;
void
msginit(void)
{
msginfo.msgmax = MSGMAX;
msginfo.msgmni = MSGMNI;
msginfo.msgmnb = MSGMNB;
msginfo.msgtql = MSGTQL;
msginfo.msgssz = MSGSSZ;
msginfo.msgseg = MSGSEG;
pool_init(&sysvmsgpl, sizeof(struct msg), 0, IPL_NONE, PR_WAITOK,
"sysvmsgpl", NULL);
TAILQ_INIT(&msg_queues);
num_ques = 0;
num_msgs = 0;
sequence = 1;
maxmsgs = 0;
}
int
sys_msgctl(struct proc *p, void *v, register_t *retval)
{
struct sys_msgctl_args /* {
syscallarg(int) msqid;
syscallarg(int) cmd;
syscallarg(struct msqid_ds *) buf;
} */ *uap = v;
return (msgctl1(p, SCARG(uap, msqid), SCARG(uap, cmd),
(caddr_t)SCARG(uap, buf), copyin, copyout));
}
int
msgctl1(struct proc *p, int msqid, int cmd, caddr_t buf,
int (*ds_copyin)(const void *, void *, size_t),
int (*ds_copyout)(const void *, void *, size_t))
{
struct msqid_ds tmp;
struct ucred *cred = p->p_ucred;
struct que *que;
int error = 0;
if ((que = que_lookup(msqid)) == NULL)
return (EINVAL);
QREF(que);
switch (cmd) {
case IPC_RMID:
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm, IPC_M)))
goto out;
TAILQ_REMOVE(&msg_queues, que, que_next);
que->que_flags |= MSGQ_DYING;
/* lose interest in the queue and wait for others to too */
if (--que->que_references > 0) {
wakeup(que);
tsleep_nsec(&que->que_references, PZERO, "msgqrm",
INFSLP);
}
que_free(que);
return (0);
case IPC_SET:
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm, IPC_M)))
goto out;
if ((error = ds_copyin(buf, &tmp, sizeof(struct msqid_ds))))
goto out;
/* only superuser can bump max bytes in queue */
if (tmp.msg_qbytes > que->msqid_ds.msg_qbytes &&
cred->cr_uid != 0) {
error = EPERM;
goto out;
}
/* restrict max bytes in queue to system limit */
if (tmp.msg_qbytes > msginfo.msgmnb)
tmp.msg_qbytes = msginfo.msgmnb;
/* can't reduce msg_bytes to 0 */
if (tmp.msg_qbytes == 0) {
error = EINVAL; /* non-standard errno! */
goto out;
}
que->msqid_ds.msg_perm.uid = tmp.msg_perm.uid;
que->msqid_ds.msg_perm.gid = tmp.msg_perm.gid;
que->msqid_ds.msg_perm.mode =
(que->msqid_ds.msg_perm.mode & ~0777) |
(tmp.msg_perm.mode & 0777);
que->msqid_ds.msg_qbytes = tmp.msg_qbytes;
que->msqid_ds.msg_ctime = gettime();
break;
case IPC_STAT:
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm, IPC_R)))
goto out;
error = ds_copyout(&que->msqid_ds, buf,
sizeof(struct msqid_ds));
break;
default:
error = EINVAL;
break;
}
out:
QRELE(que);
return (error);
}
int
sys_msgget(struct proc *p, void *v, register_t *retval)
{
struct sys_msgget_args /* {
syscallarg(key_t) key;
syscallarg(int) msgflg;
} */ *uap = v;
struct ucred *cred = p->p_ucred;
struct que *que;
key_t key = SCARG(uap, key);
int msgflg = SCARG(uap, msgflg);
int error = 0;
again:
if (key != IPC_PRIVATE) {
que = que_key_lookup(key);
if (que) {
if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL))
return (EEXIST);
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm,
msgflg & 0700)))
return (error);
goto found;
}
}
/* don't create a new message queue if the caller doesn't want to */
if (key != IPC_PRIVATE && !(msgflg & IPC_CREAT))
return (ENOENT);
/* enforce limits on the maximum number of message queues */
if (num_ques >= msginfo.msgmni)
return (ENOSPC);
/*
* if que_create returns NULL, it means that a que with an identical
* key was created while this process was sleeping, so start over
*/
if ((que = que_create(key, cred, msgflg & 0777)) == NULL)
goto again;
found:
*retval = IXSEQ_TO_IPCID(que->que_ix, que->msqid_ds.msg_perm);
return (error);
}
#define MSGQ_SPACE(q) ((q)->msqid_ds.msg_qbytes - (q)->msqid_ds.msg_cbytes)
int
sys_msgsnd(struct proc *p, void *v, register_t *retval)
{
struct sys_msgsnd_args /* {
syscallarg(int) msqid;
syscallarg(const void *) msgp;
syscallarg(size_t) msgsz;
syscallarg(int) msgflg;
} */ *uap = v;
struct ucred *cred = p->p_ucred;
struct que *que;
struct msg *msg;
size_t msgsz = SCARG(uap, msgsz);
int error;
if ((que = que_lookup(SCARG(uap, msqid))) == NULL)
return (EINVAL);
if (msgsz > que->msqid_ds.msg_qbytes || msgsz > msginfo.msgmax)
return (EINVAL);
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm, IPC_W)))
return (error);
QREF(que);
while (MSGQ_SPACE(que) < msgsz || num_msgs >= msginfo.msgtql) {
if (SCARG(uap, msgflg) & IPC_NOWAIT) {
error = EAGAIN;
goto out;
}
/* notify world that process may wedge here */
if (num_msgs >= msginfo.msgtql)
maxmsgs = 1;
que->que_flags |= MSGQ_WRITERS;
if ((error = tsleep_nsec(que, PZERO|PCATCH, "msgwait", INFSLP)))
goto out;
if (que->que_flags & MSGQ_DYING) {
error = EIDRM;
goto out;
}
}
/* if msg_create returns NULL, the queue is being removed */
if ((msg = msg_create(que)) == NULL) {
error = EIDRM;
goto out;
}
/* msg_copyin frees msg on error */
if ((error = msg_copyin(msg, (const char *)SCARG(uap, msgp), msgsz, p)))
goto out;
msg_enqueue(que, msg, p);
if (que->que_flags & MSGQ_READERS) {
que->que_flags &= ~MSGQ_READERS;
wakeup(que);
}
if (que->que_flags & MSGQ_DYING) {
error = EIDRM;
wakeup(que);
}
out:
QRELE(que);
return (error);
}
int
sys_msgrcv(struct proc *p, void *v, register_t *retval)
{
struct sys_msgrcv_args /* {
syscallarg(int) msqid;
syscallarg(void *) msgp;
syscallarg(size_t) msgsz;
syscallarg(long) msgtyp;
syscallarg(int) msgflg;
} */ *uap = v;
struct ucred *cred = p->p_ucred;
char *msgp = SCARG(uap, msgp);
struct que *que;
struct msg *msg;
size_t msgsz = SCARG(uap, msgsz);
long msgtyp = SCARG(uap, msgtyp);
int error;
if ((que = que_lookup(SCARG(uap, msqid))) == NULL)
return (EINVAL);
if ((error = ipcperm(cred, &que->msqid_ds.msg_perm, IPC_R)))
return (error);
QREF(que);
/* msg_lookup handles matching; sleeping gets handled here */
while ((msg = msg_lookup(que, msgtyp)) == NULL) {
if (SCARG(uap, msgflg) & IPC_NOWAIT) {
error = ENOMSG;
goto out;
}
que->que_flags |= MSGQ_READERS;
if ((error = tsleep_nsec(que, PZERO|PCATCH, "msgwait", INFSLP)))
goto out;
/* make sure the queue still alive */
if (que->que_flags & MSGQ_DYING) {
error = EIDRM;
goto out;
}
}
/* if msg_copyout fails, keep the message around so it isn't lost */
if ((error = msg_copyout(msg, msgp, &msgsz, p)))
goto out;
msg_dequeue(que, msg, p);
msg_free(msg);
if (que->que_flags & MSGQ_WRITERS) {
que->que_flags &= ~MSGQ_WRITERS;
wakeup(que);
}
/* ensure processes waiting on the global limit don't wedge */
if (maxmsgs) {
maxmsgs = 0;
que_wakewriters();
}
*retval = msgsz;
out:
QRELE(que);
return (error);
}
/*
* que management functions
*/
struct que *
que_create(key_t key, struct ucred *cred, int mode)
{
struct que *que, *que2;
int nextix = 1;
que = malloc(sizeof(*que), M_TEMP, M_WAIT|M_ZERO);
/* if malloc slept, a queue with the same key may have been created */
if (que_key_lookup(key)) {
free(que, M_TEMP, sizeof *que);
return (NULL);
}
/* find next available "index" */
TAILQ_FOREACH(que2, &msg_queues, que_next) {
if (nextix < que2->que_ix)
break;
nextix = que2->que_ix + 1;
}
que->que_ix = nextix;
que->msqid_ds.msg_perm.key = key;
que->msqid_ds.msg_perm.cuid = cred->cr_uid;
que->msqid_ds.msg_perm.uid = cred->cr_uid;
que->msqid_ds.msg_perm.cgid = cred->cr_gid;
que->msqid_ds.msg_perm.gid = cred->cr_gid;
que->msqid_ds.msg_perm.mode = mode & 0777;
que->msqid_ds.msg_perm.seq = ++sequence & 0x7fff;
que->msqid_ds.msg_qbytes = msginfo.msgmnb;
que->msqid_ds.msg_ctime = gettime();
TAILQ_INIT(&que->que_msgs);
/* keep queues in "index" order */
if (que2)
TAILQ_INSERT_BEFORE(que2, que, que_next);
else
TAILQ_INSERT_TAIL(&msg_queues, que, que_next);
num_ques++;
return (que);
}
struct que *
que_lookup(int id)
{
struct que *que;
TAILQ_FOREACH(que, &msg_queues, que_next)
if (que->que_ix == IPCID_TO_IX(id))
break;
/* don't return queues marked for removal */
if (que && que->que_flags & MSGQ_DYING)
return (NULL);
return (que);
}
struct que *
que_key_lookup(key_t key)
{
struct que *que;
if (key == IPC_PRIVATE)
return (NULL);
TAILQ_FOREACH(que, &msg_queues, que_next)
if (que->msqid_ds.msg_perm.key == key)
break;
/* don't return queues marked for removal */
if (que && que->que_flags & MSGQ_DYING)
return (NULL);
return (que);
}
void
que_wakewriters(void)
{
struct que *que;
TAILQ_FOREACH(que, &msg_queues, que_next) {
if (que->que_flags & MSGQ_WRITERS) {
que->que_flags &= ~MSGQ_WRITERS;
wakeup(que);
}
}
}
void
que_free(struct que *que)
{
struct msg *msg;
#ifdef DIAGNOSTIC
if (que->que_references > 0)
panic("freeing message queue with active references");
#endif
while ((msg = TAILQ_FIRST(&que->que_msgs))) {
TAILQ_REMOVE(&que->que_msgs, msg, msg_next);
msg_free(msg);
}
free(que, M_TEMP, sizeof *que);
num_ques--;
}
/*
* msg management functions
*/
struct msg *
msg_create(struct que *que)
{
struct msg *msg;
msg = pool_get(&sysvmsgpl, PR_WAITOK|PR_ZERO);
/* if the queue has died during allocation, return NULL */
if (que->que_flags & MSGQ_DYING) {
pool_put(&sysvmsgpl, msg);
wakeup(que);
return(NULL);
}
num_msgs++;
return (msg);
}
struct msg *
msg_lookup(struct que *que, int msgtyp)
{
struct msg *msg;
/*
* Three different matches are performed based on the value of msgtyp:
* 1) msgtyp > 0 => match exactly
* 2) msgtyp = 0 => match any
* 3) msgtyp < 0 => match any up to absolute value of msgtyp
*/
TAILQ_FOREACH(msg, &que->que_msgs, msg_next)
if (msgtyp == 0 || msgtyp == msg->msg_type ||
(msgtyp < 0 && -msgtyp <= msg->msg_type))
break;
return (msg);
}
void
msg_free(struct msg *msg)
{
m_freem(msg->msg_data);
pool_put(&sysvmsgpl, msg);
num_msgs--;
}
void
msg_enqueue(struct que *que, struct msg *msg, struct proc *p)
{
que->msqid_ds.msg_cbytes += msg->msg_len;
que->msqid_ds.msg_qnum++;
que->msqid_ds.msg_lspid = p->p_p->ps_pid;
que->msqid_ds.msg_stime = gettime();
TAILQ_INSERT_TAIL(&que->que_msgs, msg, msg_next);
}
void
msg_dequeue(struct que *que, struct msg *msg, struct proc *p)
{
que->msqid_ds.msg_cbytes -= msg->msg_len;
que->msqid_ds.msg_qnum--;
que->msqid_ds.msg_lrpid = p->p_p->ps_pid;
que->msqid_ds.msg_rtime = gettime();
TAILQ_REMOVE(&que->que_msgs, msg, msg_next);
}
/*
* The actual I/O routines. A note concerning the layout of SysV msg buffers:
*
* The data to be copied is laid out as a single userspace buffer, with a
* long preceding an opaque buffer of len bytes. The long value ends
* up being the message type, which needs to be copied separately from
* the buffer data, which is stored in in mbufs.
*/
int
msg_copyin(struct msg *msg, const char *ubuf, size_t len, struct proc *p)
{
struct mbuf **mm, *m;
size_t xfer;
int error;
if (msg == NULL)
panic ("msg NULL");
if ((error = copyin(ubuf, &msg->msg_type, sizeof(long)))) {
msg_free(msg);
return (error);
}
if (msg->msg_type < 1) {
msg_free(msg);
return (EINVAL);
}
ubuf += sizeof(long);
msg->msg_len = 0;
mm = &msg->msg_data;
while (msg->msg_len < len) {
m = m_get(M_WAIT, MT_DATA);
if (len >= MINCLSIZE) {
MCLGET(m, M_WAIT);
xfer = min(len, MCLBYTES);
} else {
xfer = min(len, MLEN);
}
m->m_len = xfer;
msg->msg_len += xfer;
*mm = m;
mm = &m->m_next;
}
for (m = msg->msg_data; m; m = m->m_next) {
if ((error = copyin(ubuf, mtod(m, void *), m->m_len))) {
msg_free(msg);
return (error);
}
ubuf += m->m_len;
}
return (0);
}
int
msg_copyout(struct msg *msg, char *ubuf, size_t *len, struct proc *p)
{
struct mbuf *m;
size_t xfer;
int error;
#ifdef DIAGNOSTIC
if (msg->msg_len > MSGMAX)
panic("SysV message longer than MSGMAX");
#endif
/* silently truncate messages too large for user buffer */
xfer = min(*len, msg->msg_len);
if ((error = copyout(&msg->msg_type, ubuf, sizeof(long))))
return (error);
ubuf += sizeof(long);
*len = xfer;
for (m = msg->msg_data; m; m = m->m_next) {
if ((error = copyout(mtod(m, void *), ubuf, m->m_len)))
return (error);
ubuf += m->m_len;
}
return (0);
}
int
sysctl_sysvmsg(int *name, u_int namelen, void *where, size_t *sizep)
{
struct msg_sysctl_info *info;
struct que *que;
size_t infolen, infolen0;
int error;
switch (*name) {
case KERN_SYSVIPC_MSG_INFO:
if (namelen != 1)
return (ENOTDIR);
/*
* The userland ipcs(1) utility expects to be able
* to iterate over at least msginfo.msgmni queues,
* even if those queues don't exist. This is an
* artifact of the previous implementation of
* message queues; for now, emulate this behavior
* until a more thorough fix can be made.
*/
infolen0 = sizeof(msginfo) +
msginfo.msgmni * sizeof(struct msqid_ds);
if (where == NULL) {
*sizep = infolen0;
return (0);
}
/*
* More special-casing due to previous implementation:
* if the caller just wants the msginfo struct, then
* sizep will point to the value sizeof(struct msginfo).
* In that case, only copy out the msginfo struct to
* the caller.
*/
if (*sizep == sizeof(struct msginfo))
return (copyout(&msginfo, where, sizeof(msginfo)));
info = malloc(infolen0, M_TEMP, M_WAIT|M_ZERO);
/* if the malloc slept, this may have changed */
infolen = sizeof(msginfo) +
msginfo.msgmni * sizeof(struct msqid_ds);
if (*sizep < infolen) {
free(info, M_TEMP, infolen0);
return (ENOMEM);
}
memcpy(&info->msginfo, &msginfo, sizeof(struct msginfo));
/*
* Special case #3: the previous array-based implementation
* exported the array indices and userland has come to rely
* upon these indices, so keep behavior consisitent.
*/
TAILQ_FOREACH(que, &msg_queues, que_next)
memcpy(&info->msgids[que->que_ix], &que->msqid_ds,
sizeof(struct msqid_ds));
error = copyout(info, where, infolen);
free(info, M_TEMP, infolen0);
return (error);
default:
return (EINVAL);
}
}
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