[apple/xnu.git] / osfmk / ipc / ipc_space.c

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/* 
 * Mach Operating System
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 * All Rights Reserved.
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/*
 * NOTICE: This file was modified by McAfee Research in 2004 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.
 */
/*
 */
/*
 *      File:   ipc/ipc_space.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Functions to manipulate IPC capability spaces.
 */

#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/port.h>
#include <kern/assert.h>
#include <kern/sched_prim.h>
#include <kern/zalloc.h>
#include <ipc/port.h>
#include <ipc/ipc_entry.h>
#include <ipc/ipc_object.h>
#include <ipc/ipc_hash.h>
#include <ipc/ipc_table.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_right.h>
#include <string.h>

zone_t ipc_space_zone;
ipc_space_t ipc_space_kernel;
ipc_space_t ipc_space_reply;

/*
 *      Routine:        ipc_space_reference
 *      Routine:        ipc_space_release
 *      Purpose:
 *              Function versions of the IPC space inline reference.
 */

void
ipc_space_reference(
        ipc_space_t     space)
{
        is_reference(space);
}

void
ipc_space_release(
        ipc_space_t     space)
{
        is_release(space);
}

/*
 *      Routine:        ipc_space_create
 *      Purpose:
 *              Creates a new IPC space.
 *
 *              The new space has two references, one for the caller
 *              and one because it is active.
 *      Conditions:
 *              Nothing locked.  Allocates memory.
 *      Returns:
 *              KERN_SUCCESS            Created a space.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_space_create(
        ipc_table_size_t        initial,
        ipc_space_t             *spacep)
{
        ipc_space_t space;
        ipc_entry_t table;
        ipc_entry_num_t new_size;
        mach_port_index_t index;

        space = is_alloc();
        if (space == IS_NULL)
                return KERN_RESOURCE_SHORTAGE;

        table = it_entries_alloc(initial);
        if (table == IE_NULL) {
                is_free(space);
                return KERN_RESOURCE_SHORTAGE;
        }

        new_size = initial->its_size;
        memset((void *) table, 0, new_size * sizeof(struct ipc_entry));

        /*
         *      Initialize the free list in the table.
         *      Add the entries in reverse order, and
         *      set the generation number to -1, so that
         *      initial allocations produce "natural" names.
         */
        for (index = 0; index < new_size; index++) {
                ipc_entry_t entry = &table[index];

                entry->ie_bits = IE_BITS_GEN_MASK;
                entry->ie_next = index+1;
        }
        table[new_size-1].ie_next = 0;

        is_lock_init(space);
        space->is_bits = 2; /* 2 refs, active, not growing */
        space->is_table_size = new_size;
        space->is_table = table;
        space->is_table_next = initial+1;
        space->is_task = NULL;
        space->is_low_mod = new_size;
        space->is_high_mod = 0;

        *spacep = space;
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_space_create_special
 *      Purpose:
 *              Create a special space.  A special space
 *              doesn't hold rights in the normal way.
 *              Instead it is place-holder for holding
 *              disembodied (naked) receive rights.
 *              See ipc_port_alloc_special/ipc_port_dealloc_special.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Created a space.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_space_create_special(
        ipc_space_t     *spacep)
{
        ipc_space_t space;

        space = is_alloc();
        if (space == IS_NULL)
                return KERN_RESOURCE_SHORTAGE;

        is_lock_init(space);
        space->is_bits = IS_INACTIVE | 1; /* 1 ref, not active, not growing */
        *spacep = space;
        return KERN_SUCCESS;
}

/*
 * ipc_space_clean - remove all port references from an ipc space.
 *
 * In order to follow the traditional semantic, ipc_space_destroy
 * will not destroy the entire port table of a shared space.  Instead
 * it will simply clear its own sub-space.
 */
void
ipc_space_clean(
        ipc_space_t space)
{
        ipc_entry_t table;
        ipc_entry_num_t size;
        mach_port_index_t index;

        /*
         *      If somebody is trying to grow the table,
         *      we must wait until they finish and figure
         *      out the space died.
         */
 retry:
        is_write_lock(space);
        while (is_growing(space))
                is_write_sleep(space);

        if (!is_active(space)) {
                is_write_unlock(space);
                return;
        }

        /*
         *      Now we can futz with it since we have the write lock.
         */

        table = space->is_table;
        size = space->is_table_size;

        for (index = 0; index < size; index++) {
                ipc_entry_t entry = &table[index];
                mach_port_type_t type;

                type = IE_BITS_TYPE(entry->ie_bits);
                if (type != MACH_PORT_TYPE_NONE) {
                        mach_port_name_t name = MACH_PORT_MAKE(index,
                                                IE_BITS_GEN(entry->ie_bits));
                        ipc_right_destroy(space, name, entry); /* unlocks space */
                        goto retry;
                }
        }

        /*
         * JMM - Now the table is cleaned out.  We don't bother shrinking the
         * size of the table at this point, but we probably should if it is
         * really large.
         */
        
        is_write_unlock(space);
}


/*
 *      Routine:        ipc_space_terminate
 *      Purpose:
 *              Marks the space as dead and cleans up the entries.
 *              Does nothing if the space is already dead.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_space_terminate(
        ipc_space_t     space)
{
        ipc_entry_t table;
        ipc_entry_num_t size;
        mach_port_index_t index;

        assert(space != IS_NULL);

        is_write_lock(space);
        if (!is_active(space)) {
                is_write_unlock(space);
                return;
        }
        is_mark_inactive(space);

        /*
         *      If somebody is trying to grow the table,
         *      we must wait until they finish and figure
         *      out the space died.
         */
        while (is_growing(space))
                is_write_sleep(space);

        is_write_unlock(space);


        /*
         *      Now we can futz with it unlocked.
         */

        table = space->is_table;
        size = space->is_table_size;

        for (index = 0; index < size; index++) {
                ipc_entry_t entry = &table[index];
                mach_port_type_t type;

                type = IE_BITS_TYPE(entry->ie_bits);
                if (type != MACH_PORT_TYPE_NONE) {
                        mach_port_name_t name;

                        name = MACH_PORT_MAKE(index,
                                              IE_BITS_GEN(entry->ie_bits));
                        ipc_right_terminate(space, name, entry);
                }
        }

        it_entries_free(space->is_table_next-1, table);
        space->is_table_size = 0;

        /*
         *      Because the space is now dead,
         *      we must release the "active" reference for it.
         *      Our caller still has his reference.
         */
        is_release(space);
}