load_return_t
load_machfile(
struct image_params *imgp,
struct mach_header *header,
load_result_t *result
)
{
// vnode
uint8_t *vp = imgp->ip_vp;
off_t file_offset = imgp->ip_arch_offset;
off_t macho_size = imgp->ip_arch_size;
off_t file_size = imgp->ip_vp_size;
load_result_t myresult;
load_return_t lret;
mach_vm_offset_t aslr_offset = 0;
mach_vm_offset_t dyld_aslr_offset = 0;
if (macho_size > file_size) {
return(LOAD_BADMACHO);
}
if (!result)
result = &myresult;
*result = load_result_null;
lret = parse_machfile(vp, header, file_offset, macho_size,
0, (int64_t)aslr_offset, (int64_t)dyld_aslr_offset, result);
printf("load_machfile: %s\n", load_to_string(lret));
if (lret != LOAD_SUCCESS) {
return(lret);
}
return(LOAD_SUCCESS);
}
static load_return_t
load_dylinker(
struct dylinker_command *lcp,
integer_t archbits,
int depth,
int64_t slide,
load_result_t *result
)
{
char *name;
char *p;
uint8_t *vp = NULL; /* set by get_macho_vnode() */
struct mach_header *header;
off_t file_offset = 0; /* set by get_macho_vnode() */
off_t macho_size = 0; /* set by get_macho_vnode() */
load_result_t *myresult;
kern_return_t ret;
struct macho_data *macho_data;
struct {
struct mach_header __header;
load_result_t __myresult;
struct macho_data __macho_data;
} *dyld_data;
if (lcp->cmdsize < sizeof(*lcp))
return (LOAD_BADMACHO);
name = (char *)lcp + lcp->name.offset;
/*
* Check for a proper null terminated string.
*/
p = name;
do {
if (p >= (char *)lcp + lcp->cmdsize)
return(LOAD_BADMACHO);
} while (*p++);
/* Allocate wad-of-data from heap to reduce excessively deep stacks */
printf("load_dylinker 1: %s\n", name);
dyld_data = malloc(sizeof (*dyld_data));
header = &dyld_data->__header;
myresult = &dyld_data->__myresult;
macho_data = &dyld_data->__macho_data;
ret = get_macho_vnode(name, archbits, header,
&file_offset, &macho_size, macho_data, &vp);
if (ret)
goto novp_out;
*myresult = load_result_null;
/*
* First try to map dyld in directly. This should work most of
* the time since there shouldn't normally be something already
* mapped to its address.
*/
vp = vp + file_offset;
file_offset = 0;
header = (struct mach_header*)vp;
ret = parse_machfile(vp, header, file_offset, macho_size, depth, slide, 0, myresult);
/*
* If it turned out something was in the way, then we'll take
* take this longer path to preflight dyld's vm ranges, then
* map it at a free location in the address space.
*/
if (ret == LOAD_NOSPACE) {
mach_vm_offset_t dyl_start, map_addr;
mach_vm_size_t dyl_length;
int64_t slide_amount;
*myresult = load_result_null;
/*
* Preflight parsing the Mach-O file with a NULL
* map, which will return the ranges needed for a
* subsequent map attempt (with a slide) in "myresult"
*/
ret = parse_machfile(vp, header,
file_offset, macho_size, depth,
0 /* slide */, 0, myresult);
if (ret != LOAD_SUCCESS) {
goto novp_out;
}
dyl_start = myresult->min_vm_addr;
dyl_length = myresult->max_vm_addr - myresult->min_vm_addr;
dyl_length += slide;
/* To find an appropriate load address, do a quick allocation */
map_addr = dyl_start;
map_addr = (mach_vm_offset_t)malloc(dyl_length);
if (ret == 0) {
ret = LOAD_NOSPACE;
goto novp_out;
}
free((void*)map_addr);
if (map_addr < dyl_start)
slide_amount = -(int64_t)(dyl_start - map_addr);
else
slide_amount = (int64_t)(map_addr - dyl_start);
slide_amount += slide;
*myresult = load_result_null;
ret = parse_machfile(vp, header,
file_offset, macho_size, depth,
slide_amount, 0, myresult);
if (ret) {
goto novp_out;
}
}
if (ret == LOAD_SUCCESS) {
result->dynlinker = TRUE;
result->entry_point = myresult->entry_point;
result->validentry = myresult->validentry;
result->all_image_info_addr = myresult->all_image_info_addr;
result->all_image_info_size = myresult->all_image_info_size;
}
novp_out:
free(dyld_data);
return (ret);
}
load_return_t
load_machfile(
struct image_params *imgp,
struct mach_header *header,
thread_t thread,
vm_map_t new_map,
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;
pmap_t pmap = 0; /* protected by create_map */
vm_map_t map;
vm_map_t old_map;
load_result_t myresult;
load_return_t lret;
boolean_t create_map = TRUE;
if (new_map != VM_MAP_NULL) {
create_map = FALSE;
}
if (create_map) {
old_map = current_map();
pmap = pmap_create((vm_map_size_t) 0, (imgp->ip_flags & IMGPF_IS_64BIT));
map = vm_map_create(pmap,
0,
vm_compute_max_offset((imgp->ip_flags & IMGPF_IS_64BIT)),
TRUE);
} else
map = new_map;
if ( (header->flags & MH_ALLOW_STACK_EXECUTION) )
vm_map_disable_NX(map);
if (!result)
result = &myresult;
*result = load_result_null;
lret = parse_machfile(vp, map, thread, header, file_offset, macho_size,
0, result);
if (lret != LOAD_SUCCESS) {
if (create_map) {
vm_map_deallocate(map); /* will lose pmap reference too */
}
return(lret);
}
/*
* For 64-bit users, check for presence of a 4GB page zero
* which will enable the kernel to share the user's address space
* and hence avoid TLB flushes on kernel entry/exit
*/
if ((imgp->ip_flags & IMGPF_IS_64BIT) &&
vm_map_has_4GB_pagezero(map))
vm_map_set_4GB_pagezero(map);
/*
* Commit to new map. First make sure that the current
* users of the task get done with it, and that we clean
* up the old contents of IPC and memory. The task is
* guaranteed to be single threaded upon return (us).
*
* Swap the new map for the old, which consumes our new map
* reference but each leaves us responsible for the old_map reference.
* That lets us get off the pmap associated with it, and
* then we can release it.
*/
if (create_map) {
task_halt(current_task());
old_map = swap_task_map(current_task(), map);
vm_map_clear_4GB_pagezero(old_map);
pmap_switch(pmap); /* Make sure we are using the new pmap */
vm_map_deallocate(old_map);
}
return(LOAD_SUCCESS);
}
load_return_t
load_machfile(
struct image_params *imgp,
struct mach_header *header,
thread_t thread,
vm_map_t new_map,
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 file_size = imgp->ip_vattr->va_data_size;
pmap_t pmap = 0; /* protected by create_map */
vm_map_t map;
vm_map_t old_map;
task_t old_task = TASK_NULL; /* protected by create_map */
load_result_t myresult;
load_return_t lret;
boolean_t create_map = FALSE;
int spawn = (imgp->ip_flags & IMGPF_SPAWN);
task_t task = current_task();
proc_t p = current_proc();
mach_vm_offset_t aslr_offset = 0;
kern_return_t kret;
if (macho_size > file_size) {
return(LOAD_BADMACHO);
}
if (new_map == VM_MAP_NULL) {
create_map = TRUE;
old_task = current_task();
}
/*
* If we are spawning, we have created backing objects for the process
* already, which include non-lazily creating the task map. So we
* are going to switch out the task map with one appropriate for the
* bitness of the image being loaded.
*/
if (spawn) {
create_map = TRUE;
old_task = get_threadtask(thread);
}
if (create_map) {
pmap = pmap_create(get_task_ledger(task), (vm_map_size_t) 0,
(imgp->ip_flags & IMGPF_IS_64BIT));
map = vm_map_create(pmap,
0,
vm_compute_max_offset((imgp->ip_flags & IMGPF_IS_64BIT)),
TRUE);
} else
map = new_map;
#ifndef CONFIG_ENFORCE_SIGNED_CODE
/* This turns off faulting for executable pages, which allows to
* circumvent Code Signing Enforcement */
if ( (header->flags & MH_ALLOW_STACK_EXECUTION) )
vm_map_disable_NX(map);
#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.
*/
if (!(imgp->ip_flags & IMGPF_DISABLE_ASLR)) {
aslr_offset = random();
aslr_offset %= 1 << ((imgp->ip_flags & IMGPF_IS_64BIT) ? 16 : 8);
aslr_offset <<= PAGE_SHIFT;
}
if (!result)
result = &myresult;
*result = load_result_null;
lret = parse_machfile(vp, map, thread, header, file_offset, macho_size,
0, (int64_t)aslr_offset, result);
if (lret != LOAD_SUCCESS) {
if (create_map) {
vm_map_deallocate(map); /* will lose pmap reference too */
}
return(lret);
}
#if CONFIG_EMBEDDED
/*
* Check to see if the page zero is enforced by the map->min_offset.
*/
if (vm_map_has_hard_pagezero(map, 0x1000) == FALSE) {
if (create_map) {
vm_map_deallocate(map); /* will lose pmap reference too */
}
printf("Cannot enforce a hard page-zero for %s\n", imgp->ip_strings);
psignal(vfs_context_proc(imgp->ip_vfs_context), SIGKILL);
return (LOAD_BADMACHO);
}
#else
/*
* For 64-bit users, check for presence of a 4GB page zero
* which will enable the kernel to share the user's address space
* and hence avoid TLB flushes on kernel entry/exit
*/
if ((imgp->ip_flags & IMGPF_IS_64BIT) &&
vm_map_has_4GB_pagezero(map)) {
vm_map_set_4GB_pagezero(map);
}
#endif
/*
* Commit to new map.
*
* Swap the new map for the old, which consumes our new map
* reference but each leaves us responsible for the old_map reference.
* That lets us get off the pmap associated with it, and
* then we can release it.
*/
if (create_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 (!spawn) {
/*
* 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) {
return(kret);
}
proc_transcommit(p, 0);
workqueue_mark_exiting(p);
task_complete_halt(task);
workqueue_exit(p);
}
old_map = swap_task_map(old_task, thread, map, !spawn);
vm_map_clear_4GB_pagezero(old_map);
vm_map_deallocate(old_map);
}
return(LOAD_SUCCESS);
}
static
load_return_t
load_dylinker(
struct dylinker_command *lcp,
integer_t archbits,
vm_map_t map,
thread_t thread,
int depth,
load_result_t *result,
boolean_t is_64bit
)
{
char *name;
char *p;
struct vnode *vp = NULLVP; /* set by get_macho_vnode() */
struct mach_header header;
off_t file_offset = 0; /* set by get_macho_vnode() */
off_t macho_size = 0; /* set by get_macho_vnode() */
vm_map_t copy_map;
load_result_t myresult;
kern_return_t ret;
vm_map_copy_t tmp;
mach_vm_offset_t dyl_start, map_addr;
mach_vm_size_t dyl_length;
name = (char *)lcp + lcp->name.offset;
/*
* Check for a proper null terminated string.
*/
p = name;
do {
if (p >= (char *)lcp + lcp->cmdsize)
return(LOAD_BADMACHO);
} while (*p++);
ret = get_macho_vnode(name, archbits, &header, &file_offset, &macho_size, &vp);
if (ret)
return (ret);
myresult = load_result_null;
/*
* First try to map dyld in directly. This should work most of
* the time since there shouldn't normally be something already
* mapped to its address.
*/
ret = parse_machfile(vp, map, thread, &header, file_offset, macho_size,
depth, &myresult);
/*
* If it turned out something was in the way, then we'll take
* take this longer path to map dyld into a temporary map and
* copy it into destination map at a different address.
*/
if (ret == LOAD_NOSPACE) {
/*
* Load the Mach-O.
* Use a temporary map to do the work.
*/
copy_map = vm_map_create(pmap_create(vm_map_round_page(macho_size),
is_64bit),
get_map_min(map), get_map_max(map), TRUE);
if (VM_MAP_NULL == copy_map) {
ret = LOAD_RESOURCE;
goto out;
}
myresult = load_result_null;
ret = parse_machfile(vp, copy_map, thread, &header,
file_offset, macho_size,
depth, &myresult);
if (ret) {
vm_map_deallocate(copy_map);
goto out;
}
if (get_map_nentries(copy_map) > 0) {
dyl_start = mach_get_vm_start(copy_map);
dyl_length = mach_get_vm_end(copy_map) - dyl_start;
map_addr = dyl_start;
ret = mach_vm_allocate(map, &map_addr, dyl_length, VM_FLAGS_ANYWHERE);
if (ret != KERN_SUCCESS) {
vm_map_deallocate(copy_map);
ret = LOAD_NOSPACE;
goto out;
}
ret = vm_map_copyin(copy_map,
(vm_map_address_t)dyl_start,
(vm_map_size_t)dyl_length,
TRUE, &tmp);
if (ret != KERN_SUCCESS) {
(void) vm_map_remove(map,
vm_map_trunc_page(map_addr),
vm_map_round_page(map_addr + dyl_length),
VM_MAP_NO_FLAGS);
vm_map_deallocate(copy_map);
goto out;
}
ret = vm_map_copy_overwrite(map,
(vm_map_address_t)map_addr,
tmp, FALSE);
if (ret != KERN_SUCCESS) {
vm_map_copy_discard(tmp);
(void) vm_map_remove(map,
vm_map_trunc_page(map_addr),
vm_map_round_page(map_addr + dyl_length),
VM_MAP_NO_FLAGS);
vm_map_deallocate(copy_map);
goto out;
}
if (map_addr != dyl_start)
myresult.entry_point += (map_addr - dyl_start);
} else {
ret = LOAD_FAILURE;
}
vm_map_deallocate(copy_map);
}
if (ret == LOAD_SUCCESS) {
result->dynlinker = TRUE;
result->entry_point = myresult.entry_point;
(void)ubc_map(vp, PROT_READ | PROT_EXEC);
}
out:
vnode_put(vp);
return (ret);
}
