xnu-792.22.5.tar.gz

[apple/xnu.git] / bsd / kern / sysv_shm.c

/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*      $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $      */

/*
 * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Adam Glass and Charles
 *      Hannum.
 * 4. The names of the authors may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include <sys/appleapiopts.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/shm_internal.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/ipcs.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>

#include <bsm/audit_kernel.h>

#include <mach/mach_types.h>
#include <mach/vm_inherit.h>
#include <mach/vm_map.h>

#include <mach/mach_vm.h>

#include <vm/vm_map.h>
#include <vm/vm_shared_memory_server.h>
#include <vm/vm_protos.h>

#include <kern/locks.h>

static void shminit(void *);
#if 0
SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL)
#endif 0

static lck_grp_t       *sysv_shm_subsys_lck_grp;
static lck_grp_attr_t  *sysv_shm_subsys_lck_grp_attr;
static lck_attr_t      *sysv_shm_subsys_lck_attr;
static lck_mtx_t        sysv_shm_subsys_mutex;

#define SYSV_SHM_SUBSYS_LOCK() lck_mtx_lock(&sysv_shm_subsys_mutex)
#define SYSV_SHM_SUBSYS_UNLOCK() lck_mtx_unlock(&sysv_shm_subsys_mutex)

static int oshmctl(void *p, void *uap, void *retval);
static int shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode, int * retval);
static int shmget_existing(struct shmget_args *uap, int mode, int segnum, int  * retval);
static void shmid_ds_64to32(struct user_shmid_ds *in, struct shmid_ds *out);
static void shmid_ds_32to64(struct shmid_ds *in, struct user_shmid_ds *out);

/* XXX casting to (sy_call_t *) is bogus, as usual. */
static sy_call_t *shmcalls[] = {
        (sy_call_t *)shmat, (sy_call_t *)oshmctl,
        (sy_call_t *)shmdt, (sy_call_t *)shmget,
        (sy_call_t *)shmctl
};

#define SHMSEG_FREE             0x0200
#define SHMSEG_REMOVED          0x0400
#define SHMSEG_ALLOCATED        0x0800
#define SHMSEG_WANTED           0x1000

static int shm_last_free, shm_nused, shm_committed;
struct user_shmid_ds    *shmsegs;       /* 64 bit version */
static int shm_inited = 0;

struct shm_handle {
        void * shm_object;              /* vm_offset_t kva; */
};

struct shmmap_state {
        mach_vm_address_t va;           /* user address */
        int shmid;                      /* segment id */
};

static void shm_deallocate_segment(struct user_shmid_ds *);
static int shm_find_segment_by_key(key_t);
static struct user_shmid_ds *shm_find_segment_by_shmid(int);
static int shm_delete_mapping(struct proc *, struct shmmap_state *, int);

#ifdef __APPLE_API_PRIVATE
struct  shminfo shminfo = {
        -1,     /* SHMMAX 4096 *1024 */
        -1,     /* SHMMIN = 1 */
        -1,     /* SHMMNI = 1 */
        -1,     /* SHMSEG = 8 */
        -1      /* SHMALL = 1024 */
};
#endif /* __APPLE_API_PRIVATE */

void sysv_shm_lock_init(void);

static __inline__ time_t
sysv_shmtime(void)
{
        struct timeval  tv;
        microtime(&tv);
        return (tv.tv_sec);
}

/*
 * This conversion is safe, since if we are converting for a 32 bit process,
 * then it's value of (struct shmid_ds)->shm_segsz will never exceed 4G.
 *
 * NOTE: Source and target may *NOT* overlap! (target is smaller)
 */
static void
shmid_ds_64to32(struct user_shmid_ds *in, struct shmid_ds *out)
{
        out->shm_perm = in->shm_perm;
        out->shm_segsz = (size_t)in->shm_segsz;
        out->shm_lpid = in->shm_lpid;
        out->shm_cpid = in->shm_cpid;
        out->shm_nattch = in->shm_nattch;
        out->shm_atime = in->shm_atime;
        out->shm_dtime = in->shm_dtime;
        out->shm_ctime = in->shm_ctime;
        out->shm_internal = CAST_DOWN(void *,in->shm_internal);
}

/*
 * NOTE: Source and target may are permitted to overlap! (source is smaller);
 * this works because we copy fields in order from the end of the struct to
 * the beginning.
 */
static void
shmid_ds_32to64(struct shmid_ds *in, struct user_shmid_ds *out)
{
        out->shm_internal = CAST_USER_ADDR_T(in->shm_internal);
        out->shm_ctime = in->shm_ctime;
        out->shm_dtime = in->shm_dtime;
        out->shm_atime = in->shm_atime;
        out->shm_nattch = in->shm_nattch;
        out->shm_cpid = in->shm_cpid;
        out->shm_lpid = in->shm_lpid;
        out->shm_segsz = (user_size_t)in->shm_segsz;
        out->shm_perm = in->shm_perm;
}


static int
shm_find_segment_by_key(key_t key)
{
        int i;

        for (i = 0; i < shminfo.shmmni; i++)
                if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
                    shmsegs[i].shm_perm.key == key)
                        return i;
        return -1;
}

static struct user_shmid_ds *
shm_find_segment_by_shmid(int shmid)
{
        int segnum;
        struct user_shmid_ds *shmseg;

        segnum = IPCID_TO_IX(shmid);
        if (segnum < 0 || segnum >= shminfo.shmmni)
                return NULL;
        shmseg = &shmsegs[segnum];
        if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
            != SHMSEG_ALLOCATED ||
            shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
                return NULL;
        return shmseg;
}

static void
shm_deallocate_segment(struct user_shmid_ds *shmseg)
{
        struct shm_handle *shm_handle;
        mach_vm_size_t size;

        shm_handle = CAST_DOWN(void *,shmseg->shm_internal);    /* tunnel */
        size = mach_vm_round_page(shmseg->shm_segsz);
        mach_memory_entry_port_release(shm_handle->shm_object);
        shm_handle->shm_object = NULL;
        FREE((caddr_t)shm_handle, M_SHM);
        shmseg->shm_internal = USER_ADDR_NULL;          /* tunnel */
        shm_committed -= btoc(size);
        shm_nused--;
        shmseg->shm_perm.mode = SHMSEG_FREE;
}

static int
shm_delete_mapping(__unused struct proc *p, struct shmmap_state *shmmap_s,
        int deallocate)
{
        struct user_shmid_ds *shmseg;
        int segnum, result;
        mach_vm_size_t size;

        segnum = IPCID_TO_IX(shmmap_s->shmid);
        shmseg = &shmsegs[segnum];
        size = mach_vm_round_page(shmseg->shm_segsz);   /* XXX done for us? */
        if (deallocate) {
        result = mach_vm_deallocate(current_map(), shmmap_s->va, size);
        if (result != KERN_SUCCESS)
                return EINVAL;
        }
        shmmap_s->shmid = -1;
        shmseg->shm_dtime = sysv_shmtime();
        if ((--shmseg->shm_nattch <= 0) &&
            (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
                shm_deallocate_segment(shmseg);
                shm_last_free = segnum;
        }
        return 0;
}

int
shmdt(struct proc *p, struct shmdt_args *uap, register_t *retval)
{
        struct shmmap_state *shmmap_s;
        int i;
        int shmdtret = 0;

        // LP64todo - fix this
        AUDIT_ARG(svipc_addr, CAST_DOWN(void *,uap->shmaddr));

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                shmdtret = EINVAL;
                goto shmdt_out;
        }
        shmmap_s = (struct shmmap_state *)p->vm_shm;
        if (shmmap_s == NULL) {
                shmdtret = EINVAL;
                goto shmdt_out;
        }

        for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
                if (shmmap_s->shmid != -1 &&
                    shmmap_s->va == (mach_vm_offset_t)uap->shmaddr)
                        break;
        if (i == shminfo.shmseg) {
                shmdtret = EINVAL;
                goto shmdt_out;
        }
        i = shm_delete_mapping(p, shmmap_s, 1);

        if (i == 0)
                *retval = 0;
        shmdtret = i;
shmdt_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return shmdtret;
}

int
shmat(struct proc *p, struct shmat_args *uap, register_t *retval)
{
        int error, i, flags;
        struct user_shmid_ds    *shmseg;
        struct shmmap_state     *shmmap_s = NULL;
        struct shm_handle       *shm_handle;
        mach_vm_address_t       attach_va;      /* attach address in/out */
        mach_vm_size_t          map_size;       /* size of map entry */
        vm_prot_t               prot;
        size_t                  size;
        kern_return_t           rv;
        int shmat_ret = 0;

        AUDIT_ARG(svipc_id, uap->shmid);
        // LP64todo - fix this
        AUDIT_ARG(svipc_addr, CAST_DOWN(void *,uap->shmaddr));

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                shmat_ret = EINVAL;
                goto shmat_out;
        }

        shmmap_s = (struct shmmap_state *)p->vm_shm;

        if (shmmap_s == NULL) {
                size = shminfo.shmseg * sizeof(struct shmmap_state);
                MALLOC(shmmap_s, struct shmmap_state *, size, M_SHM, M_WAITOK);
                if (shmmap_s == NULL) {
                        shmat_ret = ENOMEM;
                        goto shmat_out;
                }
                for (i = 0; i < shminfo.shmseg; i++)
                        shmmap_s[i].shmid = -1;
                p->vm_shm = (caddr_t)shmmap_s;
        }
        shmseg = shm_find_segment_by_shmid(uap->shmid);
        if (shmseg == NULL) {
                shmat_ret = EINVAL;
                goto shmat_out;
        }

        AUDIT_ARG(svipc_perm, &shmseg->shm_perm);
        error = ipcperm(kauth_cred_get(), &shmseg->shm_perm,
            (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
        if (error) {
                shmat_ret = error;
                goto shmat_out;
        }

        for (i = 0; i < shminfo.shmseg; i++) {
                if (shmmap_s->shmid == -1)
                        break;
                shmmap_s++;
        }
        if (i >= shminfo.shmseg) {
                shmat_ret = EMFILE;
                goto shmat_out;
        }

        map_size = mach_vm_round_page(shmseg->shm_segsz);
        prot = VM_PROT_READ;
        if ((uap->shmflg & SHM_RDONLY) == 0)
                prot |= VM_PROT_WRITE;
        flags = MAP_ANON | MAP_SHARED;
        if (uap->shmaddr)
                flags |= MAP_FIXED;

        attach_va = (mach_vm_address_t)uap->shmaddr;
        if (uap->shmflg & SHM_RND)
                attach_va &= ~(SHMLBA-1);
        else if ((attach_va & (SHMLBA-1)) != 0) {
                shmat_ret = EINVAL;
                goto shmat_out;
        }

        shm_handle = CAST_DOWN(void *, shmseg->shm_internal);   /* tunnel */

        rv = mach_vm_map(current_map(),                 /* process map */
                        &attach_va,                     /* attach address */
                        map_size,                       /* segment size */
                        (mach_vm_offset_t)0,            /* alignment mask */
                (flags & MAP_FIXED)? VM_FLAGS_FIXED: VM_FLAGS_ANYWHERE,
                        shm_handle->shm_object,
                        (mach_vm_offset_t)0,
                        FALSE,
                        prot,
                        prot,
                        VM_INHERIT_DEFAULT);
        if (rv != KERN_SUCCESS) 
                        goto out;

        rv = mach_vm_inherit(current_map(), attach_va, map_size, VM_INHERIT_SHARE);
        if (rv != KERN_SUCCESS) {
                (void)mach_vm_deallocate(current_map(), attach_va, map_size);
                goto out;
        }

        shmmap_s->va = attach_va;
        shmmap_s->shmid = uap->shmid;
        shmseg->shm_lpid = p->p_pid;
        shmseg->shm_atime = sysv_shmtime();
        shmseg->shm_nattch++;
        *retval = attach_va;    /* XXX return -1 on error */
        shmat_ret = 0;
        goto shmat_out;
out:
        switch (rv) {
        case KERN_INVALID_ADDRESS:
        case KERN_NO_SPACE:
                shmat_ret = ENOMEM;
        case KERN_PROTECTION_FAILURE:
                shmat_ret = EACCES;
        default:
                shmat_ret = EINVAL;
        }
shmat_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return shmat_ret;
}

static int
oshmctl(__unused void *p, __unused void *uap, __unused void *retval)
{
        return EINVAL;
}

int
shmctl(__unused struct proc *p, struct shmctl_args *uap, register_t *retval)
{
        int error;
        kauth_cred_t cred = kauth_cred_get();
        struct user_shmid_ds inbuf;
        struct user_shmid_ds *shmseg;
        size_t shmid_ds_sz = sizeof(struct user_shmid_ds);

        int shmctl_ret = 0;

        AUDIT_ARG(svipc_cmd, uap->cmd);
        AUDIT_ARG(svipc_id, uap->shmid);

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                shmctl_ret = EINVAL;
                goto shmctl_out;
        }

        if (!IS_64BIT_PROCESS(p))
                shmid_ds_sz = sizeof(struct shmid_ds);

        shmseg = shm_find_segment_by_shmid(uap->shmid);
        if (shmseg == NULL) {
                shmctl_ret = EINVAL;
                goto shmctl_out;
        }

        /* XXAUDIT: This is the perms BEFORE any change by this call. This 
         * may not be what is desired.
         */
        AUDIT_ARG(svipc_perm, &shmseg->shm_perm);

        switch (uap->cmd) {
        case IPC_STAT:
                error = ipcperm(cred, &shmseg->shm_perm, IPC_R);
                if (error) {
                        shmctl_ret = error;
                        goto shmctl_out;
                }

                if (IS_64BIT_PROCESS(p)) {
                        error = copyout(shmseg, uap->buf, sizeof(struct user_shmid_ds));
                } else {
                        struct shmid_ds shmid_ds32;
                        shmid_ds_64to32(shmseg, &shmid_ds32);
                        error = copyout(&shmid_ds32, uap->buf, sizeof(struct shmid_ds));
                }
                if (error) {
                        shmctl_ret = error;
                        goto shmctl_out;
                }
                break;
        case IPC_SET:
                error = ipcperm(cred, &shmseg->shm_perm, IPC_M);
                if (error) {
                        shmctl_ret = error;
                        goto shmctl_out;
                }
                if (IS_64BIT_PROCESS(p)) {
                        error = copyin(uap->buf, &inbuf, sizeof(struct user_shmid_ds));
                } else {
                        error = copyin(uap->buf, &inbuf, sizeof(struct shmid_ds));
                        /* convert in place; ugly, but safe */
                        shmid_ds_32to64((struct shmid_ds *)&inbuf, &inbuf);
                }
                if (error) {
                        shmctl_ret = error;
                        goto shmctl_out;
                }
                shmseg->shm_perm.uid = inbuf.shm_perm.uid;
                shmseg->shm_perm.gid = inbuf.shm_perm.gid;
                shmseg->shm_perm.mode =
                    (shmseg->shm_perm.mode & ~ACCESSPERMS) |
                    (inbuf.shm_perm.mode & ACCESSPERMS);
                shmseg->shm_ctime = sysv_shmtime();
                break;
        case IPC_RMID:
                error = ipcperm(cred, &shmseg->shm_perm, IPC_M);
                if (error) {
                        shmctl_ret = error;
                        goto shmctl_out;
                }
                shmseg->shm_perm.key = IPC_PRIVATE;
                shmseg->shm_perm.mode |= SHMSEG_REMOVED;
                if (shmseg->shm_nattch <= 0) {
                        shm_deallocate_segment(shmseg);
                        shm_last_free = IPCID_TO_IX(uap->shmid);
                }
                break;
#if 0
        case SHM_LOCK:
        case SHM_UNLOCK:
#endif
        default:
                shmctl_ret = EINVAL;
                goto shmctl_out;
        }
        *retval = 0;
        shmctl_ret = 0;
shmctl_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return shmctl_ret;
}

static int
shmget_existing(struct shmget_args *uap, int mode, int segnum, int *retval)
{
        struct user_shmid_ds *shmseg;
        int error;

        shmseg = &shmsegs[segnum];
        if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
                /*
                 * This segment is in the process of being allocated.  Wait
                 * until it's done, and look the key up again (in case the
                 * allocation failed or it was freed).
                 */
                shmseg->shm_perm.mode |= SHMSEG_WANTED;
                error = tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0);
                if (error)
                        return error;
                return EAGAIN;
        }
        error = ipcperm(kauth_cred_get(), &shmseg->shm_perm, mode);
        if (error)
                return error;
        if (uap->size && uap->size > shmseg->shm_segsz)
                return EINVAL;
       if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
                return EEXIST;
        *retval = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
        return 0;
}

static int
shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode,
        int *retval)
{
        int i, segnum, shmid, size;
        kauth_cred_t cred = kauth_cred_get();
        struct user_shmid_ds *shmseg;
        struct shm_handle *shm_handle;
        kern_return_t kret;
        vm_offset_t user_addr;
        void * mem_object;

        if (uap->size < (user_size_t)shminfo.shmmin ||
            uap->size > (user_size_t)shminfo.shmmax)
                return EINVAL;
        if (shm_nused >= shminfo.shmmni) /* any shmids left? */
                return ENOSPC;
        size = mach_vm_round_page(uap->size);
        if (shm_committed + btoc(size) > shminfo.shmall)
                return ENOMEM;
        if (shm_last_free < 0) {
                for (i = 0; i < shminfo.shmmni; i++)
                        if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
                                break;
                if (i == shminfo.shmmni)
                        panic("shmseg free count inconsistent");
                segnum = i;
        } else  {
                segnum = shm_last_free;
                shm_last_free = -1;
        }
        shmseg = &shmsegs[segnum];
        /*
         * In case we sleep in malloc(), mark the segment present but deleted
         * so that noone else tries to create the same key.
         */
        kret = vm_allocate(current_map(), &user_addr, size, VM_FLAGS_ANYWHERE);
        if (kret != KERN_SUCCESS) 
                goto out;

        kret = mach_make_memory_entry (current_map(), &size, user_addr, 
                VM_PROT_DEFAULT, (mem_entry_name_port_t *)&mem_object, 0);

        if (kret != KERN_SUCCESS) 
                goto out;

        vm_deallocate(current_map(), user_addr, size);

        shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
        shmseg->shm_perm.key = uap->key;
        shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
        MALLOC(shm_handle, struct shm_handle *, sizeof(struct shm_handle), M_SHM, M_WAITOK);
        if (shm_handle == NULL) {
                kret = KERN_NO_SPACE;
                mach_memory_entry_port_release(mem_object);
                mem_object = NULL;
                goto out;
        }
        shm_handle->shm_object = mem_object;
        shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);

        shmseg->shm_internal = CAST_USER_ADDR_T(shm_handle);    /* tunnel */
        shmseg->shm_perm.cuid = shmseg->shm_perm.uid = kauth_cred_getuid(cred);
        shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
        shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
            (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
        shmseg->shm_segsz = uap->size;
        shmseg->shm_cpid = p->p_pid;
        shmseg->shm_lpid = shmseg->shm_nattch = 0;
        shmseg->shm_atime = shmseg->shm_dtime = 0;
        shmseg->shm_ctime = sysv_shmtime();
        shm_committed += btoc(size);
        shm_nused++;
        AUDIT_ARG(svipc_perm, &shmseg->shm_perm);
        if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
                /*
                 * Somebody else wanted this key while we were asleep.  Wake
                 * them up now.
                 */
                shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
                wakeup((caddr_t)shmseg);
        }
        *retval = shmid;
        AUDIT_ARG(svipc_id, shmid);
        return 0;
out: 
        switch (kret) {
        case KERN_INVALID_ADDRESS:
        case KERN_NO_SPACE:
                return (ENOMEM);
        case KERN_PROTECTION_FAILURE:
                return (EACCES);
        default:
                return (EINVAL);
        }

}

int
shmget(struct proc *p, struct shmget_args *uap, register_t *retval)
{
        int segnum, mode, error;
        int shmget_ret = 0;
        
        /* Auditing is actually done in shmget_allocate_segment() */

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                shmget_ret = EINVAL;
                goto shmget_out;
        }

        mode = uap->shmflg & ACCESSPERMS;
        if (uap->key != IPC_PRIVATE) {
        again:
                segnum = shm_find_segment_by_key(uap->key);
                if (segnum >= 0) {
                        error = shmget_existing(uap, mode, segnum, retval);
                        if (error == EAGAIN)
                                goto again;
                        shmget_ret = error;
                        goto shmget_out;
                }
                if ((uap->shmflg & IPC_CREAT) == 0) {
                        shmget_ret = ENOENT;
                        goto shmget_out;
                }
        }
        shmget_ret = shmget_allocate_segment(p, uap, mode, retval);
shmget_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return shmget_ret;
        /*NOTREACHED*/

}

/* XXX actually varargs. */
int
shmsys(struct proc *p, struct shmsys_args *uap, register_t *retval)
{

        /* The routine that we are dispatching already does this */

        if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
                return EINVAL;
        return ((*shmcalls[uap->which])(p, &uap->a2, retval));
}

/*
 * Return 0 on success, 1 on failure.
 */
int
shmfork(struct proc *p1, struct proc *p2)
{
        struct shmmap_state *shmmap_s;
        size_t size;
        int i;
        int shmfork_ret = 0;

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                shmfork_ret = 0;
                goto shmfork_out;
        }
                
        size = shminfo.shmseg * sizeof(struct shmmap_state);
        MALLOC(shmmap_s, struct shmmap_state *, size, M_SHM, M_WAITOK);
        if (shmmap_s != NULL) {
                bcopy((caddr_t)p1->vm_shm, (caddr_t)shmmap_s, size);
                p2->vm_shm = (caddr_t)shmmap_s;
                for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
                        if (shmmap_s->shmid != -1)
                                shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
                shmfork_ret = 0;
                goto shmfork_out;
        }

        shmfork_ret = 1;        /* failed to copy to child - ENOMEM */
shmfork_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return shmfork_ret;
}

void
shmexit(struct proc *p)
{
        struct shmmap_state *shmmap_s;
        int i;

        shmmap_s = (struct shmmap_state *)p->vm_shm;

        SYSV_SHM_SUBSYS_LOCK();
        for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
                if (shmmap_s->shmid != -1)
                        shm_delete_mapping(p, shmmap_s, 1);
        FREE((caddr_t)p->vm_shm, M_SHM);
        p->vm_shm = NULL;
        SYSV_SHM_SUBSYS_UNLOCK();
}

/*
 * shmexec() is like shmexit(), only it doesn't delete the mappings,
 * since the old address space has already been destroyed and the new
 * one instantiated.  Instead, it just does the housekeeping work we
 * need to do to keep the System V shared memory subsystem sane.
 */
__private_extern__ void
shmexec(struct proc *p)
{
        struct shmmap_state *shmmap_s;
        int i;

        shmmap_s = (struct shmmap_state *)p->vm_shm;
        SYSV_SHM_SUBSYS_LOCK();
        for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
                if (shmmap_s->shmid != -1)
                        shm_delete_mapping(p, shmmap_s, 0);
        FREE((caddr_t)p->vm_shm, M_SHM);
        p->vm_shm = NULL;
        SYSV_SHM_SUBSYS_UNLOCK();
}

void
shminit(__unused void *dummy)
{
        int i;
        int s;

        if (!shm_inited) {
                /*
                 * we store internally 64 bit, since if we didn't, we would
                 * be unable to represent a segment size in excess of 32 bits
                 * with the (struct shmid_ds)->shm_segsz field; also, POSIX
                 * dictates this filed be a size_t, which is 64 bits when
                 * running 64 bit binaries.
                 */
                s = sizeof(struct user_shmid_ds) * shminfo.shmmni;

                MALLOC(shmsegs, struct user_shmid_ds *, s, M_SHM, M_WAITOK);
                if (shmsegs == NULL) {
                        /* XXX fail safely: leave shared memory uninited */
                        return;
                }
                for (i = 0; i < shminfo.shmmni; i++) {
                        shmsegs[i].shm_perm.mode = SHMSEG_FREE;
                        shmsegs[i].shm_perm.seq = 0;
                }
                shm_last_free = 0;
                shm_nused = 0;
                shm_committed = 0;
                shm_inited = 1;
        }
}
/* Initialize the mutex governing access to the SysV shm subsystem */
__private_extern__ void
sysv_shm_lock_init( void )
{

        sysv_shm_subsys_lck_grp_attr = lck_grp_attr_alloc_init();
        
        sysv_shm_subsys_lck_grp = lck_grp_alloc_init("sysv_shm_subsys_lock", sysv_shm_subsys_lck_grp_attr);
        
        sysv_shm_subsys_lck_attr = lck_attr_alloc_init();
        lck_mtx_init(&sysv_shm_subsys_mutex, sysv_shm_subsys_lck_grp, sysv_shm_subsys_lck_attr);
}

/* (struct sysctl_oid *oidp, void *arg1, int arg2, \
        struct sysctl_req *req) */
static int
sysctl_shminfo(__unused struct sysctl_oid *oidp, void *arg1,
        __unused int arg2, struct sysctl_req *req)
{
        int error = 0;
        int sysctl_shminfo_ret = 0;

        error = SYSCTL_OUT(req, arg1, sizeof(int64_t));
        if (error || req->newptr == USER_ADDR_NULL)
                return(error);

        SYSV_SHM_SUBSYS_LOCK();
        /* Set the values only if shared memory is not initialised */
        if (!shm_inited) {
                if ((error = SYSCTL_IN(req, arg1, sizeof(int64_t))) 
                    != 0) {
                        sysctl_shminfo_ret = error;
                        goto sysctl_shminfo_out;
                }

                if (arg1 == &shminfo.shmmax) {
                        if (shminfo.shmmax & PAGE_MASK_64) {
                                shminfo.shmmax = (int64_t)-1;
                                sysctl_shminfo_ret = EINVAL;
                                goto sysctl_shminfo_out;
                        }
                }

                /* Initialize only when all values are set */
                if ((shminfo.shmmax != (int64_t)-1) &&
                        (shminfo.shmmin != (int64_t)-1) &&      
                        (shminfo.shmmni != (int64_t)-1) &&
                        (shminfo.shmseg != (int64_t)-1) &&
                        (shminfo.shmall != (int64_t)-1)) {
                                shminit(NULL);
                }
        }
        sysctl_shminfo_ret = 0;
sysctl_shminfo_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return sysctl_shminfo_ret;
}

static int
IPCS_shm_sysctl(__unused struct sysctl_oid *oidp, __unused void *arg1,
        __unused int arg2, struct sysctl_req *req)
{
        int error;
        int cursor;
        union {
                struct IPCS_command u32;
                struct user_IPCS_command u64;
        } ipcs;
        struct shmid_ds shmid_ds32;     /* post conversion, 32 bit version */
        void *shmid_dsp;
        size_t ipcs_sz = sizeof(struct user_IPCS_command);
        size_t shmid_ds_sz = sizeof(struct user_shmid_ds);
        struct proc *p = current_proc();

        int ipcs__shminfo_ret = 0;

        SYSV_SHM_SUBSYS_LOCK();

        if (!shm_inited) {
                error = EINVAL;
                goto ipcs_shm_sysctl_out;
        }

        if (!IS_64BIT_PROCESS(p)) {
                ipcs_sz = sizeof(struct IPCS_command);
                shmid_ds_sz = sizeof(struct shmid_ds);
        }

        /* Copy in the command structure */
        if ((error = SYSCTL_IN(req, &ipcs, ipcs_sz)) != 0) {
                goto ipcs_shm_sysctl_out;
        }

        if (!IS_64BIT_PROCESS(p))       /* convert in place */
                ipcs.u64.ipcs_data = CAST_USER_ADDR_T(ipcs.u32.ipcs_data);

        /* Let us version this interface... */
        if (ipcs.u64.ipcs_magic != IPCS_MAGIC) {
                error = EINVAL;
                goto ipcs_shm_sysctl_out;
        }

        switch(ipcs.u64.ipcs_op) {
        case IPCS_SHM_CONF:     /* Obtain global configuration data */
                if (ipcs.u64.ipcs_datalen != sizeof(struct shminfo)) {
                        if (ipcs.u64.ipcs_cursor != 0) { /* fwd. compat. */
                                error = ENOMEM;
                                break;
                        }
                        error = ERANGE;
                        break;
                }
                error = copyout(&shminfo, ipcs.u64.ipcs_data, ipcs.u64.ipcs_datalen);
                break;

        case IPCS_SHM_ITER:     /* Iterate over existing segments */
                cursor = ipcs.u64.ipcs_cursor;
                if (cursor < 0 || cursor >= shminfo.shmmni) {
                        error = ERANGE;
                        break;
                }
                if (ipcs.u64.ipcs_datalen != (int)shmid_ds_sz) {
                        error = ENOMEM;
                        break;
                }
                for( ; cursor < shminfo.shmmni; cursor++) {
                        if (shmsegs[cursor].shm_perm.mode & SHMSEG_ALLOCATED)
                                break;
                        continue;
                }
                if (cursor == shminfo.shmmni) {
                        error = ENOENT;
                        break;
                }

                shmid_dsp = &shmsegs[cursor];   /* default: 64 bit */

                /*
                 * If necessary, convert the 64 bit kernel segment
                 * descriptor to a 32 bit user one.
                 */
                if (!IS_64BIT_PROCESS(p)) {
                        shmid_ds_64to32(shmid_dsp, &shmid_ds32);
                        shmid_dsp = &shmid_ds32;
                }
                error = copyout(shmid_dsp, ipcs.u64.ipcs_data, ipcs.u64.ipcs_datalen);
                if (!error) {
                        /* update cursor */
                        ipcs.u64.ipcs_cursor = cursor + 1;

                if (!IS_64BIT_PROCESS(p))       /* convert in place */
                        ipcs.u32.ipcs_data = CAST_DOWN(void *,ipcs.u64.ipcs_data);
                        error = SYSCTL_OUT(req, &ipcs, ipcs_sz);
                }
                break;

        default:
                error = EINVAL;
                break;
        }
ipcs_shm_sysctl_out:
        SYSV_SHM_SUBSYS_UNLOCK();
        return(error);
}

SYSCTL_NODE(_kern, KERN_SYSV, sysv, CTLFLAG_RW, 0, "SYSV");

SYSCTL_PROC(_kern_sysv, KSYSV_SHMMAX, shmmax, CTLTYPE_QUAD | CTLFLAG_RW,
    &shminfo.shmmax, 0, &sysctl_shminfo ,"Q","shmmax");

SYSCTL_PROC(_kern_sysv, KSYSV_SHMMIN, shmmin, CTLTYPE_QUAD | CTLFLAG_RW,
    &shminfo.shmmin, 0, &sysctl_shminfo ,"Q","shmmin");

SYSCTL_PROC(_kern_sysv, KSYSV_SHMMNI, shmmni, CTLTYPE_QUAD | CTLFLAG_RW,
    &shminfo.shmmni, 0, &sysctl_shminfo ,"Q","shmmni");

SYSCTL_PROC(_kern_sysv, KSYSV_SHMSEG, shmseg, CTLTYPE_QUAD | CTLFLAG_RW,
    &shminfo.shmseg, 0, &sysctl_shminfo ,"Q","shmseg");

SYSCTL_PROC(_kern_sysv, KSYSV_SHMALL, shmall, CTLTYPE_QUAD | CTLFLAG_RW,
    &shminfo.shmall, 0, &sysctl_shminfo ,"Q","shmall");

SYSCTL_NODE(_kern_sysv, OID_AUTO, ipcs, CTLFLAG_RW, 0, "SYSVIPCS");

SYSCTL_PROC(_kern_sysv_ipcs, OID_AUTO, shm, CTLFLAG_RW|CTLFLAG_ANYBODY,
        0, 0, IPCS_shm_sysctl,
        "S,IPCS_shm_command",
        "ipcs shm command interface");