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mach_loader.c
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mach_loader.c
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/*
* Copyright (c) 2000-2020 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) 1988, 1989, NeXT, Inc.
*
* File: kern/mach_loader.c
* Author: Avadis Tevanian, Jr.
*
* Mach object file loader (kernel version, for now).
*
* 21-Jul-88 Avadis Tevanian, Jr. (avie) at NeXT
* Started.
*/
#include <sys/param.h>
#include <sys/vnode_internal.h>
#include <sys/uio.h>
#include <sys/namei.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/mount_internal.h>
#include <sys/fcntl.h>
#include <sys/file_internal.h>
#include <sys/ubc_internal.h>
#include <sys/imgact.h>
#include <sys/codesign.h>
#include <sys/proc_uuid_policy.h>
#include <sys/reason.h>
#include <sys/kdebug.h>
#include <sys/spawn_internal.h>
#include <mach/mach_types.h>
#include <mach/vm_map.h> /* vm_allocate() */
#include <mach/mach_vm.h> /* mach_vm_allocate() */
#include <mach/vm_statistics.h>
#include <mach/task.h>
#include <mach/thread_act.h>
#include <machine/vmparam.h>
#include <machine/exec.h>
#include <machine/pal_routines.h>
#include <kern/ast.h>
#include <kern/kern_types.h>
#include <kern/cpu_number.h>
#include <kern/mach_loader.h>
#include <kern/mach_fat.h>
#include <kern/kalloc.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/page_decrypt.h>
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_pager.h>
#include <vm/vnode_pager.h>
#include <vm/vm_protos.h>
#include <vm/vm_shared_region.h>
#include <IOKit/IOReturn.h> /* for kIOReturnNotPrivileged */
#include <IOKit/IOBSD.h> /* for IOVnodeHasEntitlement */
#include <os/log.h>
#include <os/overflow.h>
#include "kern_exec_internal.h"
/* XXX should have prototypes in a shared header file */
extern int get_map_nentries(vm_map_t);
extern kern_return_t memory_object_signed(memory_object_control_t control,
boolean_t is_signed);
/* An empty load_result_t */
static const load_result_t load_result_null = {
.mach_header = MACH_VM_MIN_ADDRESS,
.entry_point = MACH_VM_MIN_ADDRESS,
.user_stack = MACH_VM_MIN_ADDRESS,
.user_stack_size = 0,
.user_stack_alloc = MACH_VM_MIN_ADDRESS,
.user_stack_alloc_size = 0,
.all_image_info_addr = MACH_VM_MIN_ADDRESS,
.all_image_info_size = 0,
.thread_count = 0,
.unixproc = 0,
.dynlinker = 0,
.needs_dynlinker = 0,
.validentry = 0,
.using_lcmain = 0,
.is_64bit_addr = 0,
.is_64bit_data = 0,
.custom_stack = 0,
.csflags = 0,
.has_pagezero = 0,
.uuid = { 0 },
.min_vm_addr = MACH_VM_MAX_ADDRESS,
.max_vm_addr = MACH_VM_MIN_ADDRESS,
.ro_vm_start = MACH_VM_MIN_ADDRESS,
.ro_vm_end = MACH_VM_MIN_ADDRESS,
.cs_end_offset = 0,
.threadstate = NULL,
.threadstate_sz = 0,
.is_rosetta = 0,
.dynlinker_ro_vm_start = 0,
.dynlinker_ro_vm_end = 0,
.dynlinker_mach_header = MACH_VM_MIN_ADDRESS,
.dynlinker_fd = -1,
};
/*
* Prototypes of static functions.
*/
static load_return_t
parse_machfile(
struct vnode *vp,
vm_map_t map,
thread_t thread,
struct mach_header *header,
off_t file_offset,
off_t macho_size,
int depth,
int64_t slide,
int64_t dyld_slide,
load_result_t *result,
load_result_t *binresult,
struct image_params *imgp
);
static load_return_t
load_segment(
struct load_command *lcp,
uint32_t filetype,
void *control,
off_t pager_offset,
off_t macho_size,
struct vnode *vp,
vm_map_t map,
int64_t slide,
load_result_t *result,
struct image_params *imgp
);
static load_return_t
load_uuid(
struct uuid_command *uulp,
char *command_end,
load_result_t *result
);
static load_return_t
load_version(
struct version_min_command *vmc,
boolean_t *found_version_cmd,
struct image_params *imgp,
load_result_t *result
);
static load_return_t
load_code_signature(
struct linkedit_data_command *lcp,
struct vnode *vp,
off_t macho_offset,
off_t macho_size,
cpu_type_t cputype,
cpu_subtype_t cpusubtype,
load_result_t *result,
struct image_params *imgp);
#if CONFIG_CODE_DECRYPTION
static load_return_t
set_code_unprotect(
struct encryption_info_command *lcp,
caddr_t addr,
vm_map_t map,
int64_t slide,
struct vnode *vp,
off_t macho_offset,
cpu_type_t cputype,
cpu_subtype_t cpusubtype);
#endif
static
load_return_t
load_main(
struct entry_point_command *epc,
thread_t thread,
int64_t slide,
load_result_t *result
);
static
load_return_t
setup_driver_main(
thread_t thread,
int64_t slide,
load_result_t *result
);
static load_return_t
load_unixthread(
struct thread_command *tcp,
thread_t thread,
int64_t slide,
boolean_t is_x86_64_compat_binary,
load_result_t *result
);
static load_return_t
load_threadstate(
thread_t thread,
uint32_t *ts,
uint32_t total_size,
load_result_t *
);
static load_return_t
load_threadstack(
thread_t thread,
uint32_t *ts,
uint32_t total_size,
mach_vm_offset_t *user_stack,
int *customstack,
boolean_t is_x86_64_compat_binary,
load_result_t *result
);
static load_return_t
load_threadentry(
thread_t thread,
uint32_t *ts,
uint32_t total_size,
mach_vm_offset_t *entry_point
);
static load_return_t
load_dylinker(
struct dylinker_command *lcp,
integer_t archbits,
vm_map_t map,
thread_t thread,
int depth,
int64_t slide,
load_result_t *result,
struct image_params *imgp
);
#if CONFIG_ROSETTA
static load_return_t
load_rosetta(
vm_map_t map,
thread_t thread,
load_result_t *result,
struct image_params *imgp
);
#endif
#if __x86_64__
extern int bootarg_no32exec;
static boolean_t
check_if_simulator_binary(
struct image_params *imgp,
off_t file_offset,
off_t macho_size);
#endif
struct macho_data;
static load_return_t
get_macho_vnode(
const char *path,
integer_t archbits,
struct mach_header *mach_header,
off_t *file_offset,
off_t *macho_size,
struct macho_data *macho_data,
struct vnode **vpp,
struct image_params *imgp
);
static inline void
widen_segment_command(const struct segment_command *scp32,
struct segment_command_64 *scp)
{
scp->cmd = scp32->cmd;
scp->cmdsize = scp32->cmdsize;
bcopy(scp32->segname, scp->segname, sizeof(scp->segname));
scp->vmaddr = scp32->vmaddr;
scp->vmsize = scp32->vmsize;
scp->fileoff = scp32->fileoff;
scp->filesize = scp32->filesize;
scp->maxprot = scp32->maxprot;
scp->initprot = scp32->initprot;
scp->nsects = scp32->nsects;
scp->flags = scp32->flags;
}
static void
note_all_image_info_section(const struct segment_command_64 *scp,
boolean_t is64, size_t section_size, const void *sections,
int64_t slide, load_result_t *result)
{
const union {
struct section s32;
struct section_64 s64;
} *sectionp;
unsigned int i;
if (strncmp(scp->segname, "__DATA_DIRTY", sizeof(scp->segname)) != 0 &&
strncmp(scp->segname, "__DATA", sizeof(scp->segname)) != 0) {
return;
}
for (i = 0; i < scp->nsects; ++i) {
sectionp = (const void *)
((const char *)sections + section_size * i);
if (0 == strncmp(sectionp->s64.sectname, "__all_image_info",
sizeof(sectionp->s64.sectname))) {
result->all_image_info_addr =
is64 ? sectionp->s64.addr : sectionp->s32.addr;
result->all_image_info_addr += slide;
result->all_image_info_size =
is64 ? sectionp->s64.size : sectionp->s32.size;
return;
}
}
}
#if __arm64__
/*
* Allow bypassing some security rules (hard pagezero, no write+execute)
* in exchange for better binary compatibility for legacy apps built
* before 16KB-alignment was enforced.
*/
const int fourk_binary_compatibility_unsafe = TRUE;
const int fourk_binary_compatibility_allow_wx = FALSE;
#endif /* __arm64__ */
#if __has_feature(ptrauth_calls) && XNU_TARGET_OS_OSX
/**
* Determines whether this is an arm64e process which may host in-process
* plugins.
*/
static inline bool
arm64e_plugin_host(struct image_params *imgp, load_result_t *result)
{
if (imgp->ip_flags & IMGPF_NOJOP) {
return false;
}
if (!result->platform_binary) {
return false;
}
struct cs_blob *csblob = csvnode_get_blob(imgp->ip_vp, imgp->ip_arch_offset);
const char *identity = csblob_get_identity(csblob);
if (!identity) {
return false;
}
/* Check if override host plugin entitlement is present and posix spawn attribute to disable A keys is passed */
if (IOVnodeHasEntitlement(imgp->ip_vp, (int64_t)imgp->ip_arch_offset, OVERRIDE_PLUGIN_HOST_ENTITLEMENT)) {
bool ret = imgp->ip_flags & IMGPF_PLUGIN_HOST_DISABLE_A_KEYS;
if (ret) {
proc_t p = vfs_context_proc(imgp->ip_vfs_context);
set_proc_name(imgp, p);
os_log(OS_LOG_DEFAULT, "%s: running binary \"%s\" in keys-off mode due to posix_spawnattr_disable_ptr_auth_a_keys_np", __func__, p->p_name);
}
return ret;
}
/* Disabling library validation is a good signal that this process plans to host plugins */
const char *const disable_lv_entitlements[] = {
"com.apple.security.cs.disable-library-validation",
"com.apple.private.cs.automator-plugins",
CLEAR_LV_ENTITLEMENT,
};
for (size_t i = 0; i < ARRAY_COUNT(disable_lv_entitlements); i++) {
const char *entitlement = disable_lv_entitlements[i];
if (IOVnodeHasEntitlement(imgp->ip_vp, (int64_t)imgp->ip_arch_offset, entitlement)) {
proc_t p = vfs_context_proc(imgp->ip_vfs_context);
set_proc_name(imgp, p);
os_log(OS_LOG_DEFAULT, "%s: running binary \"%s\" in keys-off mode due to entitlement: %s", __func__, p->p_name, entitlement);
return true;
}
}
/* From /System/Library/Security/HardeningExceptions.plist */
const char *const hardening_exceptions[] = {
"com.apple.perl5", /* Scripting engines may load third party code and jit*/
"com.apple.perl", /* Scripting engines may load third party code and jit*/
"org.python.python", /* Scripting engines may load third party code and jit*/
"com.apple.expect", /* Scripting engines may load third party code and jit*/
"com.tcltk.wish", /* Scripting engines may load third party code and jit*/
"com.tcltk.tclsh", /* Scripting engines may load third party code and jit*/
"com.apple.ruby", /* Scripting engines may load third party code and jit*/
"com.apple.bash", /* Required for the 'enable' command */
"com.apple.zsh", /* Required for the 'zmodload' command */
"com.apple.ksh", /* Required for 'builtin' command */
};
for (size_t i = 0; i < ARRAY_COUNT(hardening_exceptions); i++) {
if (strncmp(hardening_exceptions[i], identity, strlen(hardening_exceptions[i])) == 0) {
proc_t p = vfs_context_proc(imgp->ip_vfs_context);
set_proc_name(imgp, p);
os_log(OS_LOG_DEFAULT, "%s: running binary \"%s\" in keys-off mode due to identity: %s", __func__, p->p_name, identity);
return true;
}
}
return false;
}
#endif /* __has_feature(ptrauth_calls) && XNU_TARGET_OS_OSX */
load_return_t
load_machfile(
struct image_params *imgp,
struct mach_header *header,
thread_t thread,
vm_map_t *mapp,
load_result_t *result
)
{
struct vnode *vp = imgp->ip_vp;
off_t file_offset = imgp->ip_arch_offset;
off_t macho_size = imgp->ip_arch_size;
off_t total_size = 0;
off_t file_size = imgp->ip_vattr->va_data_size;
pmap_t pmap = 0; /* protected by create_map */
vm_map_t map;
load_result_t myresult;
load_return_t lret;
boolean_t enforce_hard_pagezero = TRUE;
int in_exec = (imgp->ip_flags & IMGPF_EXEC);
task_t task = current_task();
int64_t aslr_page_offset = 0;
int64_t dyld_aslr_page_offset = 0;
int64_t aslr_section_size = 0;
int64_t aslr_section_offset = 0;
kern_return_t kret;
unsigned int pmap_flags = 0;
if (os_add_overflow(file_offset, macho_size, &total_size) ||
total_size > file_size) {
return LOAD_BADMACHO;
}
result->is_64bit_addr = ((imgp->ip_flags & IMGPF_IS_64BIT_ADDR) == IMGPF_IS_64BIT_ADDR);
result->is_64bit_data = ((imgp->ip_flags & IMGPF_IS_64BIT_DATA) == IMGPF_IS_64BIT_DATA);
#if defined(HAS_APPLE_PAC)
pmap_flags |= (imgp->ip_flags & IMGPF_NOJOP) ? PMAP_CREATE_DISABLE_JOP : 0;
#endif /* defined(HAS_APPLE_PAC) */
#if CONFIG_ROSETTA
pmap_flags |= (imgp->ip_flags & IMGPF_ROSETTA) ? PMAP_CREATE_ROSETTA : 0;
#endif
pmap_flags |= result->is_64bit_addr ? PMAP_CREATE_64BIT : 0;
task_t ledger_task;
if (imgp->ip_new_thread) {
ledger_task = get_threadtask(imgp->ip_new_thread);
} else {
ledger_task = task;
}
#if XNU_TARGET_OS_OSX && _POSIX_SPAWN_FORCE_4K_PAGES && PMAP_CREATE_FORCE_4K_PAGES
if (imgp->ip_px_sa != NULL) {
struct _posix_spawnattr* psa = (struct _posix_spawnattr *) imgp->ip_px_sa;
if (psa->psa_flags & _POSIX_SPAWN_FORCE_4K_PAGES) {
pmap_flags |= PMAP_CREATE_FORCE_4K_PAGES;
}
}
#endif /* XNU_TARGET_OS_OSX && _POSIX_SPAWN_FORCE_4K_PAGES && PMAP_CREATE_FORCE_4K_PAGE */
pmap = pmap_create_options(get_task_ledger(ledger_task),
(vm_map_size_t) 0,
pmap_flags);
if (pmap == NULL) {
return LOAD_RESOURCE;
}
map = vm_map_create_options(pmap, 0,
vm_compute_max_offset(result->is_64bit_addr),
VM_MAP_CREATE_PAGEABLE);
#if defined(__arm64__)
if (result->is_64bit_addr) {
/* enforce 16KB alignment of VM map entries */
vm_map_set_page_shift(map, SIXTEENK_PAGE_SHIFT);
} else {
vm_map_set_page_shift(map, page_shift_user32);
}
#endif /* __arm64__ */
#if PMAP_CREATE_FORCE_4K_PAGES
if (pmap_flags & PMAP_CREATE_FORCE_4K_PAGES) {
DEBUG4K_LIFE("***** launching '%s' as 4k *****\n", vp->v_name);
vm_map_set_page_shift(map, FOURK_PAGE_SHIFT);
}
#endif /* PMAP_CREATE_FORCE_4K_PAGES */
#ifndef CONFIG_ENFORCE_SIGNED_CODE
/* This turns off faulting for executable pages, which allows
* to circumvent Code Signing Enforcement. The per process
* flag (CS_ENFORCEMENT) is not set yet, but we can use the
* global flag.
*/
if (!cs_process_global_enforcement() && (header->flags & MH_ALLOW_STACK_EXECUTION)) {
vm_map_disable_NX(map);
// TODO: Message Trace or log that this is happening
}
#endif
/* Forcibly disallow execution from data pages on even if the arch
* normally permits it. */
if ((header->flags & MH_NO_HEAP_EXECUTION) && !(imgp->ip_flags & IMGPF_ALLOW_DATA_EXEC)) {
vm_map_disallow_data_exec(map);
}
/*
* Compute a random offset for ASLR, and an independent random offset for dyld.
*/
if (!(imgp->ip_flags & IMGPF_DISABLE_ASLR)) {
vm_map_get_max_aslr_slide_section(map, &aslr_section_offset, &aslr_section_size);
aslr_section_offset = (random() % aslr_section_offset) * aslr_section_size;
aslr_page_offset = random();
aslr_page_offset = (aslr_page_offset % (vm_map_get_max_aslr_slide_pages(map) - 1)) + 1;
aslr_page_offset <<= vm_map_page_shift(map);
dyld_aslr_page_offset = random();
dyld_aslr_page_offset = (dyld_aslr_page_offset %
(vm_map_get_max_loader_aslr_slide_pages(map) - 1)) + 1;
dyld_aslr_page_offset <<= vm_map_page_shift(map);
aslr_page_offset += aslr_section_offset;
}
if (vm_map_page_shift(map) < (int)PAGE_SHIFT) {
DEBUG4K_LOAD("slide=0x%llx dyld_slide=0x%llx\n", aslr_page_offset, dyld_aslr_page_offset);
}
if (!result) {
result = &myresult;
}
*result = load_result_null;
/*
* re-set the bitness on the load result since we cleared the load result above.
*/
result->is_64bit_addr = ((imgp->ip_flags & IMGPF_IS_64BIT_ADDR) == IMGPF_IS_64BIT_ADDR);
result->is_64bit_data = ((imgp->ip_flags & IMGPF_IS_64BIT_DATA) == IMGPF_IS_64BIT_DATA);
lret = parse_machfile(vp, map, thread, header, file_offset, macho_size,
0, aslr_page_offset, dyld_aslr_page_offset, result,
NULL, imgp);
if (lret != LOAD_SUCCESS) {
vm_map_deallocate(map); /* will lose pmap reference too */
return lret;
}
#if __x86_64__
/*
* On x86, for compatibility, don't enforce the hard page-zero restriction for 32-bit binaries.
*/
if (!result->is_64bit_addr) {
enforce_hard_pagezero = FALSE;
}
/*
* For processes with IMGPF_HIGH_BITS_ASLR, add a few random high bits
* to the start address for "anywhere" memory allocations.
*/
#define VM_MAP_HIGH_START_BITS_COUNT 8
#define VM_MAP_HIGH_START_BITS_SHIFT 27
if (result->is_64bit_addr &&
(imgp->ip_flags & IMGPF_HIGH_BITS_ASLR)) {
int random_bits;
vm_map_offset_t high_start;
random_bits = random();
random_bits &= (1 << VM_MAP_HIGH_START_BITS_COUNT) - 1;
high_start = (((vm_map_offset_t)random_bits)
<< VM_MAP_HIGH_START_BITS_SHIFT);
vm_map_set_high_start(map, high_start);
}
#endif /* __x86_64__ */
/*
* Check to see if the page zero is enforced by the map->min_offset.
*/
if (enforce_hard_pagezero &&
(vm_map_has_hard_pagezero(map, 0x1000) == FALSE)) {
#if __arm64__
if (
!result->is_64bit_addr && /* not 64-bit address space */
!(header->flags & MH_PIE) && /* not PIE */
(vm_map_page_shift(map) != FOURK_PAGE_SHIFT ||
PAGE_SHIFT != FOURK_PAGE_SHIFT) && /* page size != 4KB */
result->has_pagezero && /* has a "soft" page zero */
fourk_binary_compatibility_unsafe) {
/*
* For backwards compatibility of "4K" apps on
* a 16K system, do not enforce a hard page zero...
*/
} else
#endif /* __arm64__ */
{
vm_map_deallocate(map); /* will lose pmap reference too */
return LOAD_BADMACHO;
}
}
#if __arm64__
if (enforce_hard_pagezero && result->is_64bit_addr && (header->cputype == CPU_TYPE_ARM64)) {
/* 64 bit ARM binary must have "hard page zero" of 4GB to cover the lower 32 bit address space */
if (vm_map_has_hard_pagezero(map, 0x100000000) == FALSE) {
vm_map_deallocate(map); /* will lose pmap reference too */
return LOAD_BADMACHO;
}
}
#endif
vm_commit_pagezero_status(map);
/*
* If this is an exec, then we are going to destroy the old
* task, and it's correct to halt it; if it's spawn, the
* task is not yet running, and it makes no sense.
*/
if (in_exec) {
proc_t p = current_proc();
/*
* Mark the task as halting and start the other
* threads towards terminating themselves. Then
* make sure any threads waiting for a process
* transition get informed that we are committed to
* this transition, and then finally complete the
* task halting (wait for threads and then cleanup
* task resources).
*
* NOTE: task_start_halt() makes sure that no new
* threads are created in the task during the transition.
* We need to mark the workqueue as exiting before we
* wait for threads to terminate (at the end of which
* we no longer have a prohibition on thread creation).
*
* Finally, clean up any lingering workqueue data structures
* that may have been left behind by the workqueue threads
* as they exited (and then clean up the work queue itself).
*/
kret = task_start_halt(task);
if (kret != KERN_SUCCESS) {
vm_map_deallocate(map); /* will lose pmap reference too */
return LOAD_FAILURE;
}
proc_transcommit(p, 0);
workq_mark_exiting(p);
task_complete_halt(task);
workq_exit(p);
/*
* Roll up accounting info to new task. The roll up is done after
* task_complete_halt to make sure the thread accounting info is
* rolled up to current_task.
*/
task_rollup_accounting_info(get_threadtask(thread), task);
}
*mapp = map;
#if __has_feature(ptrauth_calls) && defined(XNU_TARGET_OS_OSX)
/*
* arm64e plugin hosts currently run with JOP keys disabled, since they
* may need to run arm64 plugins.
*/
if (arm64e_plugin_host(imgp, result)) {
imgp->ip_flags |= IMGPF_NOJOP;
pmap_disable_user_jop(pmap);
}
#if CONFIG_ROSETTA
/* Disable JOP keys if the Rosetta runtime being used isn't arm64e */
if (result->is_rosetta && (imgp->ip_flags & IMGPF_NOJOP)) {
pmap_disable_user_jop(pmap);
}
#endif /* CONFIG_ROSETTA */
#endif /* __has_feature(ptrauth_calls) && defined(XNU_TARGET_OS_OSX) */
return LOAD_SUCCESS;
}
int macho_printf = 0;
#define MACHO_PRINTF(args) \
do { \
if (macho_printf) { \
printf args; \
} \
} while (0)
static boolean_t
pie_required(
cpu_type_t exectype,
cpu_subtype_t execsubtype)
{
switch (exectype) {
case CPU_TYPE_X86_64:
return FALSE;
case CPU_TYPE_ARM64:
return TRUE;
case CPU_TYPE_ARM:
switch (execsubtype) {
case CPU_SUBTYPE_ARM_V7K:
return TRUE;
}
break;
}
return FALSE;
}
/*
* The file size of a mach-o file is limited to 32 bits; this is because
* this is the limit on the kalloc() of enough bytes for a mach_header and
* the contents of its sizeofcmds, which is currently constrained to 32
* bits in the file format itself. We read into the kernel buffer the
* commands section, and then parse it in order to parse the mach-o file
* format load_command segment(s). We are only interested in a subset of
* the total set of possible commands. If "map"==VM_MAP_NULL or
* "thread"==THREAD_NULL, do not make permament VM modifications,
* just preflight the parse.
*/
static
load_return_t
parse_machfile(
struct vnode *vp,
vm_map_t map,
thread_t thread,
struct mach_header *header,
off_t file_offset,
off_t macho_size,
int depth,
int64_t aslr_offset,
int64_t dyld_aslr_offset,
load_result_t *result,
load_result_t *binresult,
struct image_params *imgp
)
{
uint32_t ncmds;
struct load_command *lcp;
struct dylinker_command *dlp = 0;
void * control;
load_return_t ret = LOAD_SUCCESS;
void * addr;
vm_size_t alloc_size, cmds_size;
size_t offset;
size_t oldoffset; /* for overflow check */
int pass;
proc_t p = vfs_context_proc(imgp->ip_vfs_context);
int error;
int resid = 0;
int spawn = (imgp->ip_flags & IMGPF_SPAWN);
size_t mach_header_sz = sizeof(struct mach_header);
boolean_t abi64;
boolean_t got_code_signatures = FALSE;
boolean_t found_header_segment = FALSE;
boolean_t found_xhdr = FALSE;
boolean_t found_version_cmd = FALSE;
int64_t slide = 0;
boolean_t dyld_no_load_addr = FALSE;
boolean_t is_dyld = FALSE;
vm_map_offset_t effective_page_mask = PAGE_MASK;
#if __arm64__
uint64_t pagezero_end = 0;
uint64_t executable_end = 0;
uint64_t writable_start = 0;
vm_map_size_t effective_page_size;
effective_page_mask = vm_map_page_mask(map);
effective_page_size = vm_map_page_size(map);
#endif /* __arm64__ */
if (header->magic == MH_MAGIC_64 ||
header->magic == MH_CIGAM_64) {
mach_header_sz = sizeof(struct mach_header_64);
}
/*
* Break infinite recursion
*/
if (depth > 2) {
return LOAD_FAILURE;
}
depth++;
/*
* Set CS_NO_UNTRUSTED_HELPERS by default; load_dylinker and load_rosetta
* will unset it if necessary.
*/
if (depth == 1) {
result->csflags |= CS_NO_UNTRUSTED_HELPERS;
}
/*
* Check to see if right machine type.
*/
if (((cpu_type_t)(header->cputype & ~CPU_ARCH_MASK) != (cpu_type() & ~CPU_ARCH_MASK))
) {
return LOAD_BADARCH;
}
if (!grade_binary(header->cputype,
header->cpusubtype & ~CPU_SUBTYPE_MASK,
header->cpusubtype & CPU_SUBTYPE_MASK, TRUE)) {
return LOAD_BADARCH;
}
abi64 = ((header->cputype & CPU_ARCH_ABI64) == CPU_ARCH_ABI64);
switch (header->filetype) {
case MH_EXECUTE:
if (depth != 1 && depth != 3) {
return LOAD_FAILURE;
}
if (header->flags & MH_DYLDLINK) {
/* Check properties of dynamic executables */
if (!(header->flags & MH_PIE) && pie_required(header->cputype, header->cpusubtype & ~CPU_SUBTYPE_MASK)) {
return LOAD_FAILURE;
}
result->needs_dynlinker = TRUE;
} else if (header->cputype == CPU_TYPE_X86_64) {
/* x86_64 static binaries allowed */
#if CONFIG_ROSETTA
} else if (imgp->ip_flags & IMGPF_ROSETTA) {
/* Rosetta runtime allowed */
#endif /* CONFIG_X86_64_COMPAT */
} else {
/* Check properties of static executables (disallowed except for development) */
#if !(DEVELOPMENT || DEBUG)
return LOAD_FAILURE;
#endif
}
break;
case MH_DYLINKER:
if (depth != 2) {
return LOAD_FAILURE;
}
is_dyld = TRUE;
break;
default:
return LOAD_FAILURE;
}
/*
* For PIE and dyld, slide everything by the ASLR offset.
*/
if ((header->flags & MH_PIE) || is_dyld) {
slide = aslr_offset;
}
/*
* Get the pager for the file.
*/
control = ubc_getobject(vp, UBC_FLAGS_NONE);
/* ensure header + sizeofcmds falls within the file */
if (os_add_overflow(mach_header_sz, header->sizeofcmds, &cmds_size) ||
(off_t)cmds_size > macho_size ||
round_page_overflow(cmds_size, &alloc_size) ||
alloc_size > INT_MAX) {
return LOAD_BADMACHO;
}
/*
* Map the load commands into kernel memory.
*/
addr = kalloc_data(alloc_size, Z_WAITOK);
if (addr == NULL) {
return LOAD_NOSPACE;
}
error = vn_rdwr(UIO_READ, vp, addr, (int)alloc_size, file_offset,
UIO_SYSSPACE, 0, vfs_context_ucred(imgp->ip_vfs_context), &resid, p);
if (error) {
kfree_data(addr, alloc_size);
return LOAD_IOERROR;
}
if (resid) {
{
/* We must be able to read in as much as the mach_header indicated */
kfree_data(addr, alloc_size);
return LOAD_BADMACHO;
}
}
/*
* Scan through the commands, processing each one as necessary.
* We parse in three passes through the headers:
* 0: determine if TEXT and DATA boundary can be page-aligned, load platform version
* 1: thread state, uuid, code signature
* 2: segments
* 3: dyld, encryption, check entry point
*/
boolean_t slide_realign = FALSE;
#if __arm64__
if (!abi64) {
slide_realign = TRUE;
}
#endif
for (pass = 0; pass <= 3; pass++) {
if (pass == 1) {
#if __arm64__
boolean_t is_pie;
int64_t adjust;
is_pie = ((header->flags & MH_PIE) != 0);
if (pagezero_end != 0 &&
pagezero_end < effective_page_size) {
/* need at least 1 page for PAGEZERO */
adjust = effective_page_size;
MACHO_PRINTF(("pagezero boundary at "
"0x%llx; adjust slide from "
"0x%llx to 0x%llx%s\n",
(uint64_t) pagezero_end,
slide,
slide + adjust,
(is_pie
? ""
: " BUT NO PIE ****** :-(")));
if (is_pie) {
slide += adjust;
pagezero_end += adjust;
executable_end += adjust;
writable_start += adjust;
}
}
if (pagezero_end != 0) {
result->has_pagezero = TRUE;
}
if (executable_end == writable_start &&
(executable_end & effective_page_mask) != 0 &&
(executable_end & FOURK_PAGE_MASK) == 0) {
/*
* The TEXT/DATA boundary is 4K-aligned but
* not page-aligned. Adjust the slide to make
* it page-aligned and avoid having a page
* with both write and execute permissions.
*/
adjust =
(effective_page_size -
(executable_end & effective_page_mask));
MACHO_PRINTF(("page-unaligned X-W boundary at "
"0x%llx; adjust slide from "
"0x%llx to 0x%llx%s\n",
(uint64_t) executable_end,
slide,
slide + adjust,
(is_pie
? ""
: " BUT NO PIE ****** :-(")));
if (is_pie) {
slide += adjust;
}
}
#endif /* __arm64__ */