[apple/xnu.git] / osfmk / kern / kext_alloc.c

/*
 * Copyright (c) 2008 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@
 */
#include <kern/assert.h>
#include <kern/debug.h>
#include <kern/kext_alloc.h>
#include <kern/misc_protos.h>

#include <mach/host_priv_server.h>
#include <mach/kern_return.h>
#include <mach/mach_vm.h>
#include <mach/vm_map.h>
#include <mach/vm_types.h>

#include <mach-o/loader.h>
#include <libkern/kernel_mach_header.h>
#include <libkern/prelink.h>
#include <libkern/OSKextLibPrivate.h>
#include <san/kasan.h>

#define KASLR_IOREG_DEBUG 0


vm_map_t g_kext_map = 0;
#if KASLR_IOREG_DEBUG
mach_vm_offset_t kext_alloc_base = 0;
mach_vm_offset_t kext_alloc_max = 0;
#else
static mach_vm_offset_t kext_alloc_base = 0;
static mach_vm_offset_t kext_alloc_max = 0;
#if CONFIG_KEXT_BASEMENT
static mach_vm_offset_t kext_post_boot_base = 0;
#endif
#endif

/*
 * On x86_64 systems, kernel extension text must remain within 2GB of the
 * kernel's text segment.  To ensure this happens, we snag 2GB of kernel VM
 * as early as possible for kext allocations.
 */
__startup_func
void
kext_alloc_init(void)
{
#if CONFIG_KEXT_BASEMENT
        kern_return_t rval = 0;
        kernel_segment_command_t *text = NULL;
        kernel_segment_command_t *prelinkTextSegment = NULL;
        mach_vm_offset_t text_end, text_start;
        mach_vm_size_t text_size;
        mach_vm_size_t kext_alloc_size;

        /* Determine the start of the kernel's __TEXT segment and determine the
         * lower bound of the allocated submap for kext allocations.
         */

        text = getsegbyname(SEG_TEXT);
        text_start = vm_map_trunc_page(text->vmaddr,
            VM_MAP_PAGE_MASK(kernel_map));
        text_start &= ~((512ULL * 1024 * 1024 * 1024) - 1);
        text_end = vm_map_round_page(text->vmaddr + text->vmsize,
            VM_MAP_PAGE_MASK(kernel_map));
        text_size = text_end - text_start;

        kext_alloc_base = KEXT_ALLOC_BASE(text_end);
        kext_alloc_size = KEXT_ALLOC_SIZE(text_size);
        kext_alloc_max = kext_alloc_base + kext_alloc_size;

        /* Post boot kext allocation will start after the prelinked kexts */
        prelinkTextSegment = getsegbyname("__PRELINK_TEXT");
        if (prelinkTextSegment) {
                /* use kext_post_boot_base to start allocations past all the prelinked
                 * kexts
                 */
                kext_post_boot_base =
                    vm_map_round_page(kext_alloc_base + prelinkTextSegment->vmsize,
                    VM_MAP_PAGE_MASK(kernel_map));
        } else {
                kext_post_boot_base = kext_alloc_base;
        }

        /* Allocate the sub block of the kernel map */
        rval = kmem_suballoc(kernel_map, (vm_offset_t *) &kext_alloc_base,
            kext_alloc_size, /* pageable */ TRUE,
            VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE,
            VM_MAP_KERNEL_FLAGS_NONE, VM_KERN_MEMORY_KEXT,
            &g_kext_map);
        if (rval != KERN_SUCCESS) {
                panic("kext_alloc_init: kmem_suballoc failed 0x%x\n", rval);
        }

        if ((kext_alloc_base + kext_alloc_size) > kext_alloc_max) {
                panic("kext_alloc_init: failed to get first 2GB\n");
        }

        if (kernel_map->min_offset > kext_alloc_base) {
                kernel_map->min_offset = kext_alloc_base;
        }

        printf("kext submap [0x%lx - 0x%lx], kernel text [0x%lx - 0x%lx]\n",
            VM_KERNEL_UNSLIDE(kext_alloc_base),
            VM_KERNEL_UNSLIDE(kext_alloc_max),
            VM_KERNEL_UNSLIDE(text->vmaddr),
            VM_KERNEL_UNSLIDE(text->vmaddr + text->vmsize));

#else
        g_kext_map = kernel_map;
        kext_alloc_base = VM_MIN_KERNEL_ADDRESS;
        kext_alloc_max = VM_MAX_KERNEL_ADDRESS;
#endif /* CONFIG_KEXT_BASEMENT */
}

/*
 * Get a vm addr in the kext submap where a kext
 * collection of given size could be mapped.
 */
vm_offset_t
get_address_from_kext_map(vm_size_t fsize)
{
        vm_offset_t addr = 0;
        kern_return_t ret;

        ret = kext_alloc(&addr, fsize, false);
        assert(ret == KERN_SUCCESS);

        if (ret != KERN_SUCCESS) {
                return 0;
        }

        kext_free(addr, fsize);

        addr += VM_MAP_PAGE_SIZE(g_kext_map);
        addr = vm_map_trunc_page(addr,
            VM_MAP_PAGE_MASK(g_kext_map));
        return addr;
}

kern_return_t
kext_alloc(vm_offset_t *_addr, vm_size_t size, boolean_t fixed)
{
        kern_return_t rval = 0;
#if CONFIG_KEXT_BASEMENT
        mach_vm_offset_t addr = (fixed) ? *_addr : kext_post_boot_base;
#else
        mach_vm_offset_t addr = (fixed) ? *_addr : kext_alloc_base;
#endif
        int flags = (fixed) ? VM_FLAGS_FIXED : VM_FLAGS_ANYWHERE;

#if CONFIG_KEXT_BASEMENT
        kc_format_t kcformat;
        if (PE_get_primary_kc_format(&kcformat) && kcformat == KCFormatFileset) {
                /*
                 * There is no need for a kext basement when booting with the
                 * new MH_FILESET format kext collection.
                 */
                rval = mach_vm_allocate_kernel(g_kext_map, &addr, size, flags, VM_KERN_MEMORY_KEXT);
                if (rval != KERN_SUCCESS) {
                        printf("vm_allocate failed - %d\n", rval);
                        goto finish;
                }
                goto check_reachable;
        }

        /* Allocate the kext virtual memory
         * 10608884 - use mach_vm_map since we want VM_FLAGS_ANYWHERE allocated past
         * kext_post_boot_base (when possible).  mach_vm_allocate will always
         * start at 0 into the map no matter what you pass in addr.  We want non
         * fixed (post boot) kext allocations to start looking for free space
         * just past where prelinked kexts have loaded.
         */
        rval = mach_vm_map_kernel(g_kext_map,
            &addr,
            size,
            0,
            flags,
            VM_MAP_KERNEL_FLAGS_NONE,
            VM_KERN_MEMORY_KEXT,
            MACH_PORT_NULL,
            0,
            TRUE,
            VM_PROT_DEFAULT,
            VM_PROT_ALL,
            VM_INHERIT_DEFAULT);
        if (rval != KERN_SUCCESS) {
                printf("mach_vm_map failed - %d\n", rval);
                goto finish;
        }
check_reachable:
#else
        rval = mach_vm_allocate_kernel(g_kext_map, &addr, size, flags, VM_KERN_MEMORY_KEXT);
        if (rval != KERN_SUCCESS) {
                printf("vm_allocate failed - %d\n", rval);
                goto finish;
        }
#endif

        /* Check that the memory is reachable by kernel text */
        if ((addr + size) > kext_alloc_max) {
                kext_free((vm_offset_t)addr, size);
                rval = KERN_INVALID_ADDRESS;
                goto finish;
        }

        *_addr = (vm_offset_t)addr;
        rval = KERN_SUCCESS;
#if KASAN
        kasan_notify_address(addr, size);
#endif

finish:
        return rval;
}

void
kext_free(vm_offset_t addr, vm_size_t size)
{
        kern_return_t rval;

        rval = mach_vm_deallocate(g_kext_map, addr, size);
        assert(rval == KERN_SUCCESS);
}

kern_return_t
kext_receipt(void **addrp, size_t *sizep)
{
        kern_return_t ret = KERN_FAILURE;
        if (addrp == NULL || sizep == NULL) {
                goto finish;
        }

        kernel_mach_header_t *kc = PE_get_kc_header(KCKindAuxiliary);
        if (kc == NULL) {
                ret = KERN_MISSING_KC;
                goto finish;
        }

        /*
         * This will be set in early boot once we've successfully checked that
         * the AuxKC is properly linked against the BootKC. If this isn't set,
         * and we have a valid AuxKC mach header, then the booter gave us a
         * bad KC.
         */
        if (auxkc_uuid_valid == FALSE) {
                ret = KERN_INVALID_KC;
                goto finish;
        }

        size_t size;
        void *addr = getsectdatafromheader(kc,
            kReceiptInfoSegment, kAuxKCReceiptSection, &size);
        if (addr == NULL) {
                ret = KERN_INVALID_KC;
                goto finish;
        }

        *addrp = addr;
        *sizep = size;
        ret = KERN_SUCCESS;

finish:
        /*
         * If we do return success, we'll want to wait for the other side to
         * call kext_receipt_set_queried themselves, so we can confirm that
         * it made the roundtrip before allowing third party kexts to load.
         */
        if (ret != KERN_SUCCESS) {
                kext_receipt_set_queried();
        }
        return ret;
}

/*
 * Returns KERN_FAILURE if the variable was already set.
 */
kern_return_t
kext_receipt_set_queried()
{
        return OSKextSetReceiptQueried();
}