xnu-2422.115.4.tar.gz

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

/*
 * Copyright (c) 2000-2007 Apple 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@
 */
/*
 *      Copyright (c) 1990, 1996-1998 Apple Computer, Inc.
 *      All Rights Reserved.
 */
/*
 * posix_shm.c : Support for POSIX shared memory APIs
 *
 *      File:   posix_shm.c
 *      Author: Ananthakrishna Ramesh
 *
 * HISTORY
 * 2-Sep-1999   A.Ramesh
 *      Created for MacOSX
 *
 */
/*
 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/file_internal.h>
#include <sys/filedesc.h>
#include <sys/stat.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/vnode_internal.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/sysproto.h>
#include <sys/proc_info.h>
#include <security/audit/audit.h>

#if CONFIG_MACF
#include <security/mac_framework.h>
#endif

#include <mach/mach_types.h>
#include <mach/mach_vm.h>
#include <mach/vm_map.h>
#include <mach/vm_prot.h>
#include <mach/vm_inherit.h>
#include <mach/kern_return.h>
#include <mach/memory_object_control.h>

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

#define f_flag f_fglob->fg_flag
#define f_type f_fglob->fg_ops->fo_type
#define f_msgcount f_fglob->fg_msgcount
#define f_cred f_fglob->fg_cred
#define f_ops f_fglob->fg_ops
#define f_offset f_fglob->fg_offset
#define f_data f_fglob->fg_data
#define PSHMNAMLEN      31      /* maximum name segment length we bother with */

struct pshmobj {
        void *                  pshmo_memobject;
        memory_object_size_t    pshmo_size;
        struct pshmobj *        pshmo_next;
};

struct pshminfo {
        unsigned int    pshm_flags;
        unsigned int    pshm_usecount;
        off_t           pshm_length;
        mode_t          pshm_mode;
        uid_t           pshm_uid;
        gid_t           pshm_gid;
        char            pshm_name[PSHMNAMLEN + 1];      /* segment name */
        struct pshmobj *pshm_memobjects;
#if DIAGNOSTIC
        unsigned int    pshm_readcount;
        unsigned int    pshm_writecount;
        proc_t          pshm_proc;
#endif /* DIAGNOSTIC */
        struct label*   pshm_label;
};
#define PSHMINFO_NULL (struct pshminfo *)0

#define PSHM_NONE       0x001
#define PSHM_DEFINED    0x002
#define PSHM_ALLOCATED  0x004
#define PSHM_MAPPED     0x008
#define PSHM_INUSE      0x010
#define PSHM_REMOVED    0x020
#define PSHM_INCREATE   0x040
#define PSHM_INDELETE   0x080
#define PSHM_ALLOCATING 0x100

struct  pshmcache {
        LIST_ENTRY(pshmcache) pshm_hash;        /* hash chain */
        struct  pshminfo *pshminfo;             /* vnode the name refers to */
        int     pshm_nlen;              /* length of name */
        char    pshm_name[PSHMNAMLEN + 1];      /* segment name */
};
#define PSHMCACHE_NULL (struct pshmcache *)0

struct  pshmstats {
        long    goodhits;               /* hits that we can really use */
        long    neghits;                /* negative hits that we can use */
        long    badhits;                /* hits we must drop */
        long    falsehits;              /* hits with id mismatch */
        long    miss;           /* misses */
        long    longnames;              /* long names that ignore cache */
};

struct pshmname {
        char    *pshm_nameptr;  /* pointer to looked up name */
        long    pshm_namelen;   /* length of looked up component */
        u_long  pshm_hash;      /* hash value of looked up name */
};

struct pshmnode {
        off_t           mapp_addr;
        user_size_t     map_size;       /* XXX unused ? */
        struct pshminfo *pinfo;
        unsigned int    pshm_usecount;
#if DIAGNOSTIC
        unsigned int readcnt;
        unsigned int writecnt;
#endif
};
#define PSHMNODE_NULL (struct pshmnode *)0


#define PSHMHASH(pnp) \
        (&pshmhashtbl[(pnp)->pshm_hash & pshmhash])

LIST_HEAD(pshmhashhead, pshmcache) *pshmhashtbl;        /* Hash Table */
u_long  pshmhash;                               /* size of hash table - 1 */
long    pshmnument;                     /* number of cache entries allocated */
struct pshmstats pshmstats;             /* cache effectiveness statistics */

static int pshm_read (struct fileproc *fp, struct uio *uio,
                    int flags, vfs_context_t ctx);
static int pshm_write (struct fileproc *fp, struct uio *uio,
                    int flags, vfs_context_t ctx);
static int pshm_ioctl (struct fileproc *fp, u_long com,
                    caddr_t data, vfs_context_t ctx);
static int pshm_select (struct fileproc *fp, int which, void *wql, vfs_context_t ctx);
static int pshm_close(struct pshminfo *pinfo, int dropref);
static int pshm_closefile (struct fileglob *fg, vfs_context_t ctx);

static int pshm_kqfilter(struct fileproc *fp, struct knote *kn, vfs_context_t ctx);

int pshm_access(struct pshminfo *pinfo, int mode, kauth_cred_t cred, proc_t p);
static int pshm_cache_add(struct pshminfo *pshmp, struct pshmname *pnp, struct pshmcache *pcp);
static void pshm_cache_delete(struct pshmcache *pcp);
#if NOT_USED
static void pshm_cache_purge(void);
#endif  /* NOT_USED */
static int pshm_cache_search(struct pshminfo **pshmp, struct pshmname *pnp,
        struct pshmcache **pcache, int addref);

static const struct fileops pshmops = {
        DTYPE_PSXSHM,
        pshm_read,
        pshm_write,
        pshm_ioctl,
        pshm_select,
        pshm_closefile,
        pshm_kqfilter,
        0
};

static lck_grp_t       *psx_shm_subsys_lck_grp;
static lck_grp_attr_t  *psx_shm_subsys_lck_grp_attr;
static lck_attr_t      *psx_shm_subsys_lck_attr;
static lck_mtx_t        psx_shm_subsys_mutex;

#define PSHM_SUBSYS_LOCK() lck_mtx_lock(& psx_shm_subsys_mutex)
#define PSHM_SUBSYS_UNLOCK() lck_mtx_unlock(& psx_shm_subsys_mutex)


/* Initialize the mutex governing access to the posix shm subsystem */
__private_extern__ void
pshm_lock_init( void )
{

    psx_shm_subsys_lck_grp_attr = lck_grp_attr_alloc_init();

    psx_shm_subsys_lck_grp = lck_grp_alloc_init("posix shared memory", psx_shm_subsys_lck_grp_attr);

    psx_shm_subsys_lck_attr = lck_attr_alloc_init();
    lck_mtx_init(& psx_shm_subsys_mutex, psx_shm_subsys_lck_grp, psx_shm_subsys_lck_attr);
}

/*
 * Lookup an entry in the cache 
 * 
 * 
 * status of -1 is returned if matches
 * If the lookup determines that the name does not exist
 * (negative cacheing), a status of ENOENT is returned. If the lookup
 * fails, a status of zero is returned.
 */

static int
pshm_cache_search(struct pshminfo **pshmp, struct pshmname *pnp,
        struct pshmcache **pcache, int addref)
{
        struct pshmcache *pcp, *nnp;
        struct pshmhashhead *pcpp;

        if (pnp->pshm_namelen > PSHMNAMLEN) {
                pshmstats.longnames++;
                return (0);
        }

        pcpp = PSHMHASH(pnp);
        for (pcp = pcpp->lh_first; pcp != 0; pcp = nnp) {
                nnp = pcp->pshm_hash.le_next;
                if (pcp->pshm_nlen == pnp->pshm_namelen &&
                    !bcmp(pcp->pshm_name, pnp->pshm_nameptr,                                            (u_int)pcp-> pshm_nlen))
                        break;
        }

        if (pcp == 0) {
                pshmstats.miss++;
                return (0);
        }

        /* We found a "positive" match, return the vnode */
        if (pcp->pshminfo) {
                pshmstats.goodhits++;
                /* TOUCH(ncp); */
                *pshmp = pcp->pshminfo;
                *pcache = pcp;
                if (addref)
                        pcp->pshminfo->pshm_usecount++;
                return (-1);
        }

        /*
         * We found a "negative" match, ENOENT notifies client of this match.
         * The nc_vpid field records whether this is a whiteout.
         */
        pshmstats.neghits++;
        return (ENOENT);
}

/*
 * Add an entry to the cache.
 * XXX should be static?
 */
static int
pshm_cache_add(struct pshminfo *pshmp, struct pshmname *pnp, struct pshmcache *pcp)
{
        struct pshmhashhead *pcpp;
        struct pshminfo *dpinfo;
        struct pshmcache *dpcp;

#if DIAGNOSTIC
        if (pnp->pshm_namelen > PSHMNAMLEN)
                panic("cache_enter: name too long");
#endif


        /*  if the entry has already been added by some one else return */
        if (pshm_cache_search(&dpinfo, pnp, &dpcp, 0) == -1) {
                return(EEXIST);
        }
        pshmnument++;

        /*
         * Fill in cache info, if vp is NULL this is a "negative" cache entry.
         * For negative entries, we have to record whether it is a whiteout.
         * the whiteout flag is stored in the nc_vpid field which is
         * otherwise unused.
         */
        pcp->pshminfo = pshmp;
        pcp->pshm_nlen = pnp->pshm_namelen;
        bcopy(pnp->pshm_nameptr, pcp->pshm_name, (unsigned)pcp->pshm_nlen);
        pcpp = PSHMHASH(pnp);
#if DIAGNOSTIC
        {
                struct pshmcache *p;

                for (p = pcpp->lh_first; p != 0; p = p->pshm_hash.le_next)
                        if (p == pcp)
                                panic("cache_enter: duplicate");
        }
#endif
        LIST_INSERT_HEAD(pcpp, pcp, pshm_hash);
        return(0);
}

/*
 * Name cache initialization, from vfs_init() when we are booting
 */
void
pshm_cache_init(void)
{
        pshmhashtbl = hashinit(desiredvnodes / 8, M_SHM, &pshmhash);
}

#if NOT_USED
/*
 * Invalidate a all entries to particular vnode.
 * 
 * We actually just increment the v_id, that will do it. The entries will
 * be purged by lookup as they get found. If the v_id wraps around, we
 * need to ditch the entire cache, to avoid confusion. No valid vnode will
 * ever have (v_id == 0).
 */
static void
pshm_cache_purge(void)
{
        struct pshmcache *pcp;
        struct pshmhashhead *pcpp;

        for (pcpp = &pshmhashtbl[pshmhash]; pcpp >= pshmhashtbl; pcpp--) {
                while ( (pcp = pcpp->lh_first) )
                        pshm_cache_delete(pcp);
        }
}
#endif  /* NOT_USED */

static void
pshm_cache_delete(struct pshmcache *pcp)
{
#if DIAGNOSTIC
        if (pcp->pshm_hash.le_prev == 0)
                panic("namecache purge le_prev");
        if (pcp->pshm_hash.le_next == pcp)
                panic("namecache purge le_next");
#endif /* DIAGNOSTIC */
        LIST_REMOVE(pcp, pshm_hash);
        pcp->pshm_hash.le_prev = 0;     
        pshmnument--;
}


int
shm_open(proc_t p, struct shm_open_args *uap, int32_t *retval)
{
        size_t  i;
        int indx, error;
        struct pshmname nd;
        struct pshminfo *pinfo;
        struct fileproc *fp = NULL;
        char *pnbuf = NULL;
        struct pshminfo *new_pinfo = PSHMINFO_NULL;
        struct pshmnode *new_pnode = PSHMNODE_NULL;
        struct pshmcache *pcache = PSHMCACHE_NULL;      /* ignored on return */
        char * nameptr;
        char * cp;
        size_t pathlen, plen;
        int fmode ;
        int cmode = uap->mode;
        int incache = 0;
        struct pshmcache *pcp = NULL;

        AUDIT_ARG(fflags, uap->oflag);
        AUDIT_ARG(mode, uap->mode);

        pinfo = PSHMINFO_NULL;

        /*
         * Preallocate everything we might need up front to avoid taking
         * and dropping the lock, opening us up to race conditions.
         */
        MALLOC_ZONE(pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
        if (pnbuf == NULL) {
                error = ENOSPC;
                goto bad;
        }

        pathlen = MAXPATHLEN;
        error = copyinstr(uap->name, (void *)pnbuf, MAXPATHLEN, &pathlen);
        if (error) {
                goto bad;
        }
        AUDIT_ARG(text, pnbuf);
        if (pathlen > PSHMNAMLEN) {
                error = ENAMETOOLONG;
                goto bad;
        }
#ifdef PSXSHM_NAME_RESTRICT
        nameptr = pnbuf;
        if (*nameptr == '/') {
                while (*(nameptr++) == '/') {
                        plen--;
                        error = EINVAL;
                        goto bad;
                }
        } else {
                error = EINVAL;
                goto bad;
        }
#endif /* PSXSHM_NAME_RESTRICT */

        plen = pathlen;
        nameptr = pnbuf;
        nd.pshm_nameptr = nameptr;
        nd.pshm_namelen = plen;
        nd. pshm_hash =0;

        for (cp = nameptr, i=1; *cp != 0 && i <= plen; i++, cp++) {
                nd.pshm_hash += (unsigned char)*cp * i;
        }

        /*
         * attempt to allocate a new fp; if unsuccessful, the fp will be
         * left unmodified (NULL).
         */
        error = falloc(p, &fp, &indx, vfs_context_current());
        if (error) 
                goto bad;

        cmode &=  ALLPERMS;

        fmode = FFLAGS(uap->oflag);
        if ((fmode & (FREAD | FWRITE)) == 0) {
                error = EINVAL;
                goto bad;
        }

        /*
         * We allocate a new entry if we are less than the maximum
         * allowed and the one at the front of the LRU list is in use.
         * Otherwise we use the one at the front of the LRU list.
         */
        MALLOC(pcp, struct pshmcache *, sizeof(struct pshmcache), M_SHM, M_WAITOK|M_ZERO);
        if (pcp == NULL) {
                error = ENOSPC;
                goto bad;
        }

        MALLOC(new_pinfo, struct pshminfo *, sizeof(struct pshminfo), M_SHM, M_WAITOK|M_ZERO);
        if (new_pinfo == PSHMINFO_NULL) {
                error = ENOSPC;
                goto bad;
        }
#if CONFIG_MACF
        mac_posixshm_label_init(new_pinfo);
#endif

        MALLOC(new_pnode, struct pshmnode *, sizeof(struct pshmnode), M_SHM, M_WAITOK|M_ZERO);
        if (new_pnode == PSHMNODE_NULL) {
                error = ENOSPC;
                goto bad;
        }

        PSHM_SUBSYS_LOCK();

        /*
         * If we find the entry in the cache, this will take a reference,
         * allowing us to unlock it for the permissions check.
         */
        error = pshm_cache_search(&pinfo, &nd, &pcache, 1);

        PSHM_SUBSYS_UNLOCK();

        if (error == ENOENT) {
                error = EINVAL;
                goto bad;
        }

        if (!error) {
                incache = 0;
                if (fmode & O_CREAT) {
                        /*  create a new one (commit the allocation) */
                        pinfo = new_pinfo;
                        pinfo->pshm_flags = PSHM_DEFINED | PSHM_INCREATE;
                        pinfo->pshm_usecount = 1; /* existence reference */
                        pinfo->pshm_mode = cmode;
                        pinfo->pshm_uid = kauth_getuid();
                        pinfo->pshm_gid = kauth_getgid();
                        bcopy(pnbuf, &pinfo->pshm_name[0], pathlen);
                        pinfo->pshm_name[pathlen]=0;
#if CONFIG_MACF
                        error = mac_posixshm_check_create(kauth_cred_get(), nameptr);
                        if (error) {
                                goto bad;
                        }
                        mac_posixshm_label_associate(kauth_cred_get(), pinfo, nameptr);
#endif
                }
        } else {
                incache = 1;
                if (fmode & O_CREAT) {
                        /*  already exists */
                        if ((fmode & O_EXCL)) {
                                AUDIT_ARG(posix_ipc_perm, pinfo->pshm_uid,
                                                pinfo->pshm_gid,
                                                pinfo->pshm_mode);

                                /* shm obj exists and opened O_EXCL */
                                error = EEXIST;
                                goto bad;
                        } 

                        if( pinfo->pshm_flags & PSHM_INDELETE) {
                                error = ENOENT;
                                goto bad;
                        }       
                        AUDIT_ARG(posix_ipc_perm, pinfo->pshm_uid,
                                        pinfo->pshm_gid, pinfo->pshm_mode);
#if CONFIG_MACF 
                        if ((error = mac_posixshm_check_open(kauth_cred_get(), pinfo, fmode))) {
                                goto bad;
                        }
#endif
                        if ( (error = pshm_access(pinfo, fmode, kauth_cred_get(), p)) ) {
                                goto bad;
                        }
                }
        }
        if (!(fmode & O_CREAT)) {
                if (!incache) {
                        /* O_CREAT is not set and the object does not exist */
                        error = ENOENT;
                        goto bad;
                }
                if( pinfo->pshm_flags & PSHM_INDELETE) {
                        error = ENOENT;
                        goto bad;
                }       
#if CONFIG_MACF 
                if ((error = mac_posixshm_check_open(kauth_cred_get(), pinfo, fmode))) {
                        goto bad;
                }
#endif

                if ((error = pshm_access(pinfo, fmode, kauth_cred_get(), p))) {
                        goto bad;
                }
        }
        if (fmode & O_TRUNC) {
                error = EINVAL;
                goto bad;
        }


        PSHM_SUBSYS_LOCK();

#if DIAGNOSTIC 
        if (fmode & FWRITE)
                pinfo->pshm_writecount++;
        if (fmode & FREAD)
                pinfo->pshm_readcount++;
#endif
        if (!incache) {
                /* if successful, this will consume the pcp */
                if ( (error = pshm_cache_add(pinfo, &nd, pcp)) ) {
                        goto bad_locked;
                }
                /*
                 * add reference for the new entry; otherwise, we obtained
                 * one from the cache hit earlier.
                 */
                pinfo->pshm_usecount++;
        }
        pinfo->pshm_flags &= ~PSHM_INCREATE;
        new_pnode->pinfo = pinfo;

        PSHM_SUBSYS_UNLOCK();

        /*
         * if incache, we did not use the new pcp or new_pinfo and must
         * free them
         */
        if (incache) {
                FREE(pcp, M_SHM);

                if (new_pinfo != PSHMINFO_NULL) {
#if CONFIG_MACF
                        mac_posixshm_label_destroy(new_pinfo);
#endif
                        FREE(new_pinfo, M_SHM);
                }
        }

        proc_fdlock(p);
        fp->f_flag = fmode & FMASK;
        fp->f_ops = &pshmops;
        fp->f_data = (caddr_t)new_pnode;
        *fdflags(p, indx) |= UF_EXCLOSE;
        procfdtbl_releasefd(p, indx, NULL);
        fp_drop(p, indx, fp, 1);
        proc_fdunlock(p);

        *retval = indx;
        FREE_ZONE(pnbuf, MAXPATHLEN, M_NAMEI);
        return (0);

bad_locked:
        PSHM_SUBSYS_UNLOCK();
bad:
        /*
         * If we obtained the entry from the cache, we need to drop the
         * reference; holding the reference may have prevented unlinking,
         * so we need to call pshm_close() to get the full effect.
         */
        if (incache) {
                PSHM_SUBSYS_LOCK();
                pshm_close(pinfo, 1);
                PSHM_SUBSYS_UNLOCK();
        }

        if (pcp != NULL)
                FREE(pcp, M_SHM);

        if (new_pnode != PSHMNODE_NULL)
                FREE(new_pnode, M_SHM);

        if (fp != NULL)
                fp_free(p, indx, fp);

        if (new_pinfo != PSHMINFO_NULL) {
#if CONFIG_MACF
                mac_posixshm_label_destroy(new_pinfo);
#endif
                FREE(new_pinfo, M_SHM);
        }
        if (pnbuf != NULL)
                FREE_ZONE(pnbuf, MAXPATHLEN, M_NAMEI);
        return (error);
}


int
pshm_truncate(__unused proc_t p, struct fileproc *fp, __unused int fd, 
                                off_t length, __unused int32_t *retval)
{
        struct pshminfo * pinfo;
        struct pshmnode * pnode ;
        kern_return_t kret;
        mem_entry_name_port_t mem_object;
        mach_vm_size_t total_size, alloc_size;
        memory_object_size_t mosize;
        struct pshmobj *pshmobj, *pshmobj_next, **pshmobj_next_p;
        vm_map_t        user_map;
#if CONFIG_MACF
        int error;
#endif

        user_map = current_map();

        if (fp->f_type != DTYPE_PSXSHM) {
                return(EINVAL);
        }
        

        if (((pnode = (struct pshmnode *)fp->f_data)) == PSHMNODE_NULL )
                return(EINVAL);

        PSHM_SUBSYS_LOCK();
        if ((pinfo = pnode->pinfo) == PSHMINFO_NULL) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }
        if ((pinfo->pshm_flags & (PSHM_DEFINED|PSHM_ALLOCATING|PSHM_ALLOCATED)) 
                        != PSHM_DEFINED) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }
#if CONFIG_MACF
        error = mac_posixshm_check_truncate(kauth_cred_get(), pinfo, length);
        if (error) {
                PSHM_SUBSYS_UNLOCK();
                return(error);
        }
#endif

        pinfo->pshm_flags |= PSHM_ALLOCATING;
        total_size = vm_map_round_page(length,
                                       vm_map_page_mask(user_map));
        pshmobj_next_p = &pinfo->pshm_memobjects;

        for (alloc_size = 0;
             alloc_size < total_size;
             alloc_size += mosize) {

                PSHM_SUBSYS_UNLOCK();

                mosize = MIN(total_size - alloc_size, ANON_MAX_SIZE);
                kret = mach_make_memory_entry_64(
                        VM_MAP_NULL,
                        &mosize,
                        0,
                        MAP_MEM_NAMED_CREATE | VM_PROT_DEFAULT,
                        &mem_object,
                        0);

                if (kret != KERN_SUCCESS) 
                        goto out;

                MALLOC(pshmobj, struct pshmobj *, sizeof (struct pshmobj),
                       M_SHM, M_WAITOK);
                if (pshmobj == NULL) {
                        kret = KERN_NO_SPACE;
                        mach_memory_entry_port_release(mem_object);
                        mem_object = NULL;
                        goto out;
                }

                PSHM_SUBSYS_LOCK();

                pshmobj->pshmo_memobject = (void *) mem_object;
                pshmobj->pshmo_size = mosize;
                pshmobj->pshmo_next = NULL;
                
                *pshmobj_next_p = pshmobj;
                pshmobj_next_p = &pshmobj->pshmo_next;
        }
        
        pinfo->pshm_flags = PSHM_ALLOCATED;
        pinfo->pshm_length = total_size;
        PSHM_SUBSYS_UNLOCK();
        return(0);

out:
        PSHM_SUBSYS_LOCK();
        for (pshmobj = pinfo->pshm_memobjects;
             pshmobj != NULL;
             pshmobj = pshmobj_next) {
                pshmobj_next = pshmobj->pshmo_next;
                mach_memory_entry_port_release(pshmobj->pshmo_memobject);
                FREE(pshmobj, M_SHM);
        }
        pinfo->pshm_memobjects = NULL;
        pinfo->pshm_flags &= ~PSHM_ALLOCATING;
        PSHM_SUBSYS_UNLOCK();

        switch (kret) {
        case KERN_INVALID_ADDRESS:
        case KERN_NO_SPACE:
                return (ENOMEM);
        case KERN_PROTECTION_FAILURE:
                return (EACCES);
        default:
                return (EINVAL);
        
        }
}

int
pshm_stat(struct pshmnode *pnode, void *ub, int isstat64)
{
        struct stat *sb = (struct stat *)0;     /* warning avoidance ; protected by isstat64 */
        struct stat64 * sb64 = (struct stat64 *)0;  /* warning avoidance ; protected by isstat64 */
        struct pshminfo *pinfo;
#if CONFIG_MACF
        int error;
#endif
        
        PSHM_SUBSYS_LOCK();
        if ((pinfo = pnode->pinfo) == PSHMINFO_NULL){
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }

#if CONFIG_MACF
        error = mac_posixshm_check_stat(kauth_cred_get(), pinfo);
        if (error) {
                PSHM_SUBSYS_UNLOCK();
                return(error);
        }
#endif

        if (isstat64 != 0) {
                sb64 = (struct stat64 *)ub;
                bzero(sb64, sizeof(struct stat64)); 
                sb64->st_mode = pinfo->pshm_mode;
                sb64->st_uid = pinfo->pshm_uid;
                sb64->st_gid = pinfo->pshm_gid;
                sb64->st_size = pinfo->pshm_length;
        } else {
                sb = (struct stat *)ub;
                bzero(sb, sizeof(struct stat)); 
                sb->st_mode = pinfo->pshm_mode;
                sb->st_uid = pinfo->pshm_uid;
                sb->st_gid = pinfo->pshm_gid;
                sb->st_size = pinfo->pshm_length;
        }
        PSHM_SUBSYS_UNLOCK();

        return(0);
}

/*
 * This is called only from shm_open which holds pshm_lock();
 * XXX This code is repeated many times
 */
int
pshm_access(struct pshminfo *pinfo, int mode, kauth_cred_t cred, __unused proc_t p)
{
        int mode_req = ((mode & FREAD) ? S_IRUSR : 0) |
                       ((mode & FWRITE) ? S_IWUSR : 0);

        /* Otherwise, user id 0 always gets access. */
        if (!suser(cred, NULL))
                return (0);

        return(posix_cred_access(cred, pinfo->pshm_uid, pinfo->pshm_gid, pinfo->pshm_mode, mode_req));
}

int
pshm_mmap(__unused proc_t p, struct mmap_args *uap, user_addr_t *retval, struct fileproc *fp, off_t pageoff) 
{
        vm_map_offset_t user_addr = (vm_map_offset_t)uap->addr;
        vm_map_size_t   user_size = (vm_map_size_t)uap->len ;
        vm_map_offset_t user_start_addr;
        vm_map_size_t   map_size, mapped_size;
        int prot = uap->prot;
        int flags = uap->flags;
        vm_object_offset_t file_pos = (vm_object_offset_t)uap->pos;
        vm_object_offset_t map_pos;
        vm_map_t        user_map;
        int             alloc_flags;
        boolean_t       docow;
        kern_return_t   kret;
        struct pshminfo * pinfo;
        struct pshmnode * pnode;
        struct pshmobj * pshmobj;
#if CONFIG_MACF
        int error;
#endif

        if (user_size == 0) 
                return(0);

        if ((flags & MAP_SHARED) == 0)
                return(EINVAL);


        if ((prot & PROT_WRITE) && ((fp->f_flag & FWRITE) == 0)) {
                return(EPERM);
        }

        if (((pnode = (struct pshmnode *)fp->f_data)) == PSHMNODE_NULL )
                return(EINVAL);

        PSHM_SUBSYS_LOCK();
        if ((pinfo = pnode->pinfo) == PSHMINFO_NULL) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }

        if ((pinfo->pshm_flags & PSHM_ALLOCATED) != PSHM_ALLOCATED) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }
        if ((off_t)user_size > pinfo->pshm_length) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }
        if ((off_t)(user_size + file_pos) > pinfo->pshm_length) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }
        if ((pshmobj = pinfo->pshm_memobjects) == NULL) {
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }

#if CONFIG_MACF
        error = mac_posixshm_check_mmap(kauth_cred_get(), pinfo, prot, flags);
        if (error) {
                PSHM_SUBSYS_UNLOCK();
                return(error);
        }
#endif

        PSHM_SUBSYS_UNLOCK();
        user_map = current_map();

        if ((flags & MAP_FIXED) == 0) {
                alloc_flags = VM_FLAGS_ANYWHERE;
                user_addr = vm_map_round_page(user_addr,
                                              vm_map_page_mask(user_map)); 
        } else {
                if (user_addr != vm_map_round_page(user_addr,
                                                   vm_map_page_mask(user_map)))
                        return (EINVAL);
                /*
                 * We do not get rid of the existing mappings here because
                 * it wouldn't be atomic (see comment in mmap()).  We let
                 * Mach VM know that we want it to replace any existing
                 * mapping with the new one.
                 */
                alloc_flags = VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE;
        }
        docow = FALSE;  

        mapped_size = 0;

        /* reserver the entire space first... */
        kret = vm_map_enter_mem_object(user_map,
                                       &user_addr,
                                       user_size,
                                       0,
                                       alloc_flags,
                                       IPC_PORT_NULL,
                                       0,
                                       FALSE,
                                       VM_PROT_NONE,
                                       VM_PROT_NONE,
                                       VM_INHERIT_NONE);
        user_start_addr = user_addr;
        if (kret != KERN_SUCCESS) {
                goto out;
        }

        /* ... and overwrite with the real mappings */
        for (map_pos = 0, pshmobj = pinfo->pshm_memobjects;
             user_size != 0;
             map_pos += pshmobj->pshmo_size, pshmobj = pshmobj->pshmo_next) {
                if (pshmobj == NULL) {
                        /* nothing there to map !? */
                        goto out;
                }
                if (file_pos >= map_pos + pshmobj->pshmo_size) {
                        continue;
                }
                map_size = pshmobj->pshmo_size - (file_pos - map_pos);
                if (map_size > user_size) {
                        map_size = user_size;
                }
                kret = vm_map_enter_mem_object(
                        user_map,
                        &user_addr,
                        map_size,
                        0,
                        VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE,
                        pshmobj->pshmo_memobject,
                        file_pos - map_pos,
                        docow,
                        prot,
                        VM_PROT_DEFAULT, 
                        VM_INHERIT_SHARE);
                if (kret != KERN_SUCCESS) 
                        goto out;

                user_addr += map_size;
                user_size -= map_size;
                mapped_size += map_size;
                file_pos += map_size;
        }

        PSHM_SUBSYS_LOCK();
        pnode->mapp_addr = user_start_addr;
        pnode->map_size = mapped_size;
        pinfo->pshm_flags |= (PSHM_MAPPED | PSHM_INUSE);
        PSHM_SUBSYS_UNLOCK();
out:
        if (kret != KERN_SUCCESS) {
                if (mapped_size != 0) {
                        (void) mach_vm_deallocate(current_map(),
                                                  user_start_addr,
                                                  mapped_size);
                }
        }

        switch (kret) {
        case KERN_SUCCESS:
                *retval = (user_start_addr + pageoff);
                return (0);
        case KERN_INVALID_ADDRESS:
        case KERN_NO_SPACE:
                return (ENOMEM);
        case KERN_PROTECTION_FAILURE:
                return (EACCES);
        default:
                return (EINVAL);
        }

}

int
shm_unlink(__unused proc_t p, struct shm_unlink_args *uap, 
                        __unused int32_t *retval)
{
        size_t i;
        int error=0;
        struct pshmname nd;
        struct pshminfo *pinfo;
        char * pnbuf;
        char * nameptr;
        char * cp;
        size_t pathlen, plen;
        int incache = 0;
        struct pshmcache *pcache = PSHMCACHE_NULL;
        struct pshmobj *pshmobj, *pshmobj_next;

        pinfo = PSHMINFO_NULL;

        MALLOC_ZONE(pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
        if (pnbuf == NULL) {
                return(ENOSPC);         /* XXX non-standard */
        }
        pathlen = MAXPATHLEN;
        error = copyinstr(uap->name, (void *)pnbuf, MAXPATHLEN, &pathlen);
        if (error) {
                goto bad;
        }
        AUDIT_ARG(text, pnbuf);
        if (pathlen > PSHMNAMLEN) {
                error = ENAMETOOLONG;
                goto bad;
        }


#ifdef PSXSHM_NAME_RESTRICT
        nameptr = pnbuf;
        if (*nameptr == '/') {
                while (*(nameptr++) == '/') {
                        plen--;
                        error = EINVAL;
                        goto bad;
                }
        } else {
                error = EINVAL;
                goto bad;
        }
#endif /* PSXSHM_NAME_RESTRICT */

        plen = pathlen;
        nameptr = pnbuf;
        nd.pshm_nameptr = nameptr;
        nd.pshm_namelen = plen;
        nd. pshm_hash =0;

        for (cp = nameptr, i=1; *cp != 0 && i <= plen; i++, cp++) {
               nd.pshm_hash += (unsigned char)*cp * i;
        }

        PSHM_SUBSYS_LOCK();
        error = pshm_cache_search(&pinfo, &nd, &pcache, 0);

        if (error == ENOENT) {
                PSHM_SUBSYS_UNLOCK();
                goto bad;

        }
        /* During unlink lookup failure also implies ENOENT */ 
        if (!error) {
                PSHM_SUBSYS_UNLOCK();
                error = ENOENT;
                goto bad;
        } else
                incache = 1;

        if ((pinfo->pshm_flags & (PSHM_DEFINED | PSHM_ALLOCATED))==0) {
                PSHM_SUBSYS_UNLOCK();
                error = EINVAL;
                goto bad;
        }

        if (pinfo->pshm_flags & PSHM_ALLOCATING) {
                /* XXX should we wait for flag to clear and then proceed ? */
                PSHM_SUBSYS_UNLOCK();
                error = EAGAIN;
                goto bad;
        }

        if (pinfo->pshm_flags & PSHM_INDELETE) {
                PSHM_SUBSYS_UNLOCK();
                error = 0;
                goto bad;
        }
#if CONFIG_MACF
        error = mac_posixshm_check_unlink(kauth_cred_get(), pinfo, nameptr);
        if (error) {
                PSHM_SUBSYS_UNLOCK();
                goto bad;
        }
#endif

        AUDIT_ARG(posix_ipc_perm, pinfo->pshm_uid, pinfo->pshm_gid,
                  pinfo->pshm_mode);

        /* 
         * following file semantics, unlink should be allowed 
         * for users with write permission only. 
         */
        if ( (error = pshm_access(pinfo, FWRITE, kauth_cred_get(), p)) ) {
                PSHM_SUBSYS_UNLOCK();
                goto bad;
        }

        pinfo->pshm_flags |= PSHM_INDELETE;
        pshm_cache_delete(pcache);
        pinfo->pshm_flags |= PSHM_REMOVED;
        /* release the existence reference */
        if (!--pinfo->pshm_usecount) {
#if CONFIG_MACF
                mac_posixshm_label_destroy(pinfo);
#endif
                PSHM_SUBSYS_UNLOCK();
                /*
                 * If this is the last reference going away on the object,
                 * then we need to destroy the backing object.  The name
                 * has an implied but uncounted reference on the object,
                 * once it's created, since it's used as a rendezvous, and
                 * therefore may be subsequently reopened.
                 */
                for (pshmobj = pinfo->pshm_memobjects;
                     pshmobj != NULL;
                     pshmobj = pshmobj_next) {
                        mach_memory_entry_port_release(pshmobj->pshmo_memobject);
                        pshmobj_next = pshmobj->pshmo_next;
                        FREE(pshmobj, M_SHM);
                }
                FREE(pinfo,M_SHM);
        } else {
                PSHM_SUBSYS_UNLOCK();
        }
        FREE(pcache, M_SHM);
        error = 0;
bad:
        FREE_ZONE(pnbuf, MAXPATHLEN, M_NAMEI);
        return (error);
}

/* already called locked */
static int
pshm_close(struct pshminfo *pinfo, int dropref)
{
        int error = 0;
        struct pshmobj *pshmobj, *pshmobj_next;

        /*
         * If we are dropping the reference we took on the cache object, don't
         * enforce the allocation requirement.
         */
        if ( !dropref && ((pinfo->pshm_flags & PSHM_ALLOCATED) != PSHM_ALLOCATED)) {
                return(EINVAL);
        }
#if DIAGNOSTIC
        if(!pinfo->pshm_usecount) {
                kprintf("negative usecount in pshm_close\n");
        }
#endif /* DIAGNOSTIC */
        pinfo->pshm_usecount--; /* release this fd's reference */

        if ((pinfo->pshm_flags & PSHM_REMOVED) && !pinfo->pshm_usecount) {
#if CONFIG_MACF
                mac_posixshm_label_destroy(pinfo);
#endif
                PSHM_SUBSYS_UNLOCK();
                /*
                 * If this is the last reference going away on the object,
                 * then we need to destroy the backing object.
                 */
                for (pshmobj = pinfo->pshm_memobjects;
                     pshmobj != NULL;
                     pshmobj = pshmobj_next) {
                        mach_memory_entry_port_release(pshmobj->pshmo_memobject);
                        pshmobj_next = pshmobj->pshmo_next;
                        FREE(pshmobj, M_SHM);
                }
                PSHM_SUBSYS_LOCK();
                FREE(pinfo,M_SHM);
        }
        return (error);
}

/* vfs_context_t passed to match prototype for struct fileops */
static int
pshm_closefile(struct fileglob *fg, __unused vfs_context_t ctx)
{
        int error = EINVAL;
        struct pshmnode *pnode;

        PSHM_SUBSYS_LOCK();

        if ((pnode = (struct pshmnode *)fg->fg_data) != NULL) {
                if (pnode->pinfo != PSHMINFO_NULL) {
                        error =  pshm_close(pnode->pinfo, 0);
                }
                FREE(pnode, M_SHM);
        }

        PSHM_SUBSYS_UNLOCK();

        return(error);
}

static int
pshm_read(__unused struct fileproc *fp, __unused struct uio *uio, 
                        __unused int flags, __unused vfs_context_t ctx)
{
        return(ENOTSUP);
}

static int
pshm_write(__unused struct fileproc *fp, __unused struct uio *uio, 
                        __unused int flags, __unused vfs_context_t ctx)
{
        return(ENOTSUP);
}

static int
pshm_ioctl(__unused struct fileproc *fp, __unused u_long com, 
                        __unused caddr_t data, __unused vfs_context_t ctx)
{
        return(ENOTSUP);
}

static int
pshm_select(__unused struct fileproc *fp, __unused int which, __unused void *wql, 
                        __unused vfs_context_t ctx)
{
        return(ENOTSUP);
}

static int
pshm_kqfilter(__unused struct fileproc *fp, __unused struct knote *kn, 
                                __unused vfs_context_t ctx)
{
        return(ENOTSUP);
}

int
fill_pshminfo(struct pshmnode * pshm, struct pshm_info * info)
{
        struct pshminfo *pinfo;
        struct vinfo_stat *sb;
        
        PSHM_SUBSYS_LOCK();
        if ((pinfo = pshm->pinfo) == PSHMINFO_NULL){
                PSHM_SUBSYS_UNLOCK();
                return(EINVAL);
        }

        sb = &info->pshm_stat;

        bzero(sb, sizeof(struct vinfo_stat)); 
        sb->vst_mode = pinfo->pshm_mode;
        sb->vst_uid = pinfo->pshm_uid;
        sb->vst_gid = pinfo->pshm_gid;
        sb->vst_size = pinfo->pshm_length;

        info->pshm_mappaddr = pshm->mapp_addr;
        bcopy(&pinfo->pshm_name[0], &info->pshm_name[0], PSHMNAMLEN+1); 

        PSHM_SUBSYS_UNLOCK();
        return(0);
}

#if CONFIG_MACF
void
pshm_label_associate(struct fileproc *fp, struct vnode *vp, vfs_context_t ctx)
{
        struct pshmnode *pnode;
        struct pshminfo *pshm;

        PSHM_SUBSYS_LOCK();
        pnode = (struct pshmnode *)fp->f_fglob->fg_data;
        if (pnode != NULL) {
                pshm = pnode->pinfo;
                if (pshm != NULL)
                        mac_posixshm_vnode_label_associate(
                                vfs_context_ucred(ctx), pshm, pshm->pshm_label,
                                vp, vp->v_label);
        }
        PSHM_SUBSYS_UNLOCK();
}
#endif