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Legilimency/BCMClient.py
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# Legilimency - Memory Analysis Framework for iOS | |
# -------------------------------------- | |
# | |
# Written and maintained by Gal Beniamini <laginimaineb@google.com> | |
# | |
# Copyright 2017 Google Inc. All Rights Reserved. | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
from MemClient import MemClient, qword_at | |
from defs import * | |
from symbols import * | |
from kalloc import * | |
from AppleBCMWLANPCIeSubmissionRing import AppleBCMWLANPCIeSubmissionRing | |
from AppleBCMWLANPCIeCompletionRing import AppleBCMWLANPCIeCompletionRing | |
from DART import DART | |
import time, struct | |
#The size of the allocation for the PCIe object | |
PCIE_OBJECT_ALLOCATION_SIZE = 3824 | |
#The offset of the internal object representing SoC memory access within the PCIe object | |
CHIP_INTERNAL_OBJECT_OFFSET = 896 | |
#The offset of the TCM field within the internal object | |
TCM_OFFSET = 144 | |
#The offset of the RAM offset field in the internal object | |
RAM_OFFSET_OFFSET = 132 | |
#The offset of the RAM size field in the internal object | |
RAM_SIZE_OFFSET = 136 | |
#The size of the embedded firmware log array | |
LOG_ARRAY_SIZE = 80 | |
#The offset of the IOMapper instance in the PCIe object | |
IO_MAPPER_OFFSET = 808 | |
#The offset of the IOVMAllocator instance in the IOMapper instance | |
IO_VM_ALLOCATOR_OFFSET = 240 | |
#The offset of the AppleS5L8960XDART instance in the IOVMAllocator instance | |
SL_DART_OFFSET = 24 | |
#The offset of the resource map field in the PCIe object | |
RESOURCE_MAP_OFFSET = 696 | |
#The offset of the resource array field in the resource map instance | |
RESOURCE_ARRAY_OFFSET = 24 | |
#The offset of the max resource ID field in the resource map instance | |
MAX_RESOURCE_ID_OFFSET = 20 | |
#The offset of the resource mapping object within the resource instance | |
MAPPING_OBJ_OFFSET = 32 | |
#The offset of the resource data offset field in the resource instance | |
RESOURCE_DATA_OFFSET_OFFSET = 40 | |
#The offset of the resource data array field in the resource instance | |
RESOURCE_DATA_ARRAY_OFFSET = 72 | |
#The size of an entry in the resource data array | |
RESOURCE_ENTRY_SIZE = 16 | |
#The offset of the resource offset field in the resource instance | |
RESOURCE_OFFSET_OFFSET = 64 | |
#The offset of the resource length field in the resource instance | |
RESOURCE_LENGTH_OFFSET = 68 | |
#The offset of the mbuf field in the resource instance | |
RESOURCE_MBUF_OFFSET = 56 | |
#The time, in seconds, to wait when polling for a code chunk's hook on wl_hc to complete | |
HOOK_POLL_DELAY = 0.5 | |
#The time, in seconds, to wait when polling the firmware for a crash | |
REBOOT_POLL_DELAY = 0.1 | |
class BCMClient(object): | |
""" | |
This client is used to control the BCM Wi-Fi SoC by manipulating it's TCM. | |
""" | |
def __init__(self, client): | |
""" | |
Creates a new client, using the underlying MemShell client. Automatically | |
locates the PCIe object in the kalloc zones and extracts the TCM's location. | |
""" | |
self.client = client | |
self.pcie_obj = find_object_by_vtable(self.client, PCIE_OBJECT_VTABLE + self.client.slide(), PCIE_OBJECT_ALLOCATION_SIZE) | |
internal_object = self.client.read64(self.pcie_obj + CHIP_INTERNAL_OBJECT_OFFSET) | |
self.tcm = self.client.read64(internal_object + TCM_OFFSET) | |
self.ram_offset = self.client.read32(internal_object + RAM_OFFSET_OFFSET) | |
self.ram_size = self.client.read32(internal_object + RAM_SIZE_OFFSET) | |
def get_pcie_obj(self): | |
""" | |
Returns the address of the PCIe object. | |
""" | |
return self.pcie_obj | |
def fw_check_range(self, fw_addr, size): | |
""" | |
Checks that the given address range falls within the firmware's TCM, and raises | |
an exception otherwise. | |
""" | |
if not (self.ram_offset <= fw_addr <= (self.ram_offset + self.ram_size)) or \ | |
not (self.ram_offset <= (fw_addr + size) <= (self.ram_offset + self.ram_size)): | |
raise Exception("Illegal FW read range: [%08X,%08X]" % (fw_addr, fw_addr + size)) | |
def fw_read(self, fw_addr, size): | |
""" | |
Reads an arbitrarily large block from the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, size) | |
return self.client.read(self.tcm + fw_addr - self.ram_offset, size) | |
def fw_read128(self, fw_addr): | |
""" | |
Reads a 128-bit value from the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, struct.calcsize("QQ")) | |
return self.client.read128(self.tcm + fw_addr - self.ram_offset) | |
def fw_read64(self, fw_addr): | |
""" | |
Reads a 64-bit value from the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, QWORD_SIZE) | |
return self.client.read64(self.tcm + fw_addr - self.ram_offset) | |
def fw_read32(self, fw_addr): | |
""" | |
Reads a 32-bit value from the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, DWORD_SIZE) | |
return self.client.read32(self.tcm + fw_addr - self.ram_offset) | |
def fw_write64(self, fw_addr, val): | |
""" | |
Writes a 64-bit value to the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, QWORD_SIZE) | |
self.client.write64(self.tcm + fw_addr - self.ram_offset, val) | |
def fw_write32(self, fw_addr, val): | |
""" | |
Writes a 32-bit value to the firmware's TCM. | |
""" | |
self.fw_check_range(fw_addr, DWORD_SIZE) | |
self.client.write32(self.tcm + fw_addr - self.ram_offset, val) | |
def fw_write8(self, fw_addr, val): | |
""" | |
Writes an 8-bit value to the firmware's TCM. | |
""" | |
#Ensuring this is a valid range (including trailing bits after the last byte read) | |
dword_off = fw_addr % DWORD_SIZE | |
aligned_addr = fw_addr - dword_off | |
self.fw_check_range(aligned_addr, DWORD_SIZE) | |
#Switching the previous byte to the target one | |
prev_val = self.fw_read32(aligned_addr) | |
val_bytes = [b for b in struct.pack("<I", prev_val)] | |
val_bytes[dword_off] = chr(val) | |
#Updating the 32-bit word at the aligned address | |
new_val = struct.unpack("<I", "".join(val_bytes))[0] | |
self.fw_write32(aligned_addr, new_val) | |
def read_ram(self): | |
""" | |
Reads the firmware's entire RAM. | |
""" | |
return self.fw_read(self.ram_offset, self.ram_size) | |
def execute_chunk(self, code_chunk, is_thumb=True): | |
""" | |
Executes the given code chunk on the Wi-Fi firmare. | |
""" | |
#Writing the chunk's contents to some unused memory in the heap's head | |
code_chunk += "\x00" * (QWORD_SIZE - (len(code_chunk) % QWORD_SIZE)) #Pad to QWORD | |
hook_ptr = HOOK_ADDRESS + (1 if is_thumb else 0) | |
for i in range(0, len(code_chunk), QWORD_SIZE): | |
self.fw_write64(HOOK_ADDRESS + i, struct.unpack("<Q", code_chunk[i:i+QWORD_SIZE])[0]) | |
#Hook the WL_HC pointer | |
self.fw_write32(WL_HC_PTR, hook_ptr) | |
#Wait for the chunk to unhook the pointer (signaling completion) | |
while self.fw_read32(WL_HC_PTR) == hook_ptr: | |
time.sleep(HOOK_POLL_DELAY) | |
def reboot_firmware(self): | |
""" | |
Reboots the firmware by corrupting a periodically executed function pointer | |
""" | |
self.fw_write32(WL_HC_PTR, GARBAGE_VALUE) | |
while self.fw_read32(WL_HC_PTR) == GARBAGE_VALUE: | |
time.sleep(REBOOT_POLL_DELAY) | |
def get_allowed_heap_ranges(self): | |
""" | |
Returns the list of allowed heap ranges | |
""" | |
num_descs = self.fw_read32(ALLOWED_HEAP_RANGES_COUNT_PTR) | |
ranges = [] | |
for i in range(0, num_descs): | |
range_base = self.fw_read32(ALLOWED_HEAP_RANGES_ARRAY_ADDR + i*(2*DWORD_SIZE) + DWORD_SIZE) | |
range_size = self.fw_read32(ALLOWED_HEAP_RANGES_ARRAY_ADDR + i*(2*DWORD_SIZE)) | |
ranges.append((range_base, range_base+range_size)) | |
return ranges | |
def get_disallowed_heap_ranges(self): | |
""" | |
Returns the list of disallowed heap ranges | |
""" | |
curr = DISALLOWED_HEAP_RANGES_PTR | |
ranges = [] | |
while curr != 0: | |
next_addr = self.fw_read32(curr + DWORD_SIZE) | |
if next_addr == 0: | |
break | |
size = self.fw_read32(next_addr) | |
ranges.append((next_addr, next_addr + size)) | |
curr = next_addr | |
return ranges | |
def get_enabled_log_tags(self): | |
""" | |
Returns the list of enabled log tags | |
""" | |
log_status_array = self.fw_read32(LOG_STATUS_ARRAY_PTR) | |
log_status_bytes = self.fw_read(log_status_array, LOG_ARRAY_SIZE) | |
return [i for i in range(0, LOG_ARRAY_SIZE) if ord(log_status_bytes[i]) & 0x40] | |
def enable_log(self, tag): | |
""" | |
Enables the given log tag in the logging configuration array | |
""" | |
log_status_array = self.fw_read32(LOG_STATUS_ARRAY_PTR) | |
self.fw_write8(log_status_array + tag, 0xC0) | |
def disable_log(self, tag): | |
""" | |
Disables the given log tag in the logging configuration array | |
""" | |
log_status_array = self.fw_read32(LOG_STATUS_ARRAY_PTR) | |
self.fw_write8(log_status_array + tag, 0x00) | |
def get_resource(self, resource_array_data, resource_id): | |
""" | |
Returns a tuple containing the resource information for the resource with the given ID, | |
or None if no such resource exists. The tuple contains the following information: | |
(resource_addr, data_addr, offset, length, mbuf, addr_ptr_offset) | |
""" | |
#Getting the resource object | |
resource = qword_at(resource_array_data, resource_id) | |
if resource == 0: | |
return None | |
#Retrieving the data address by following the mappings | |
data_addr = 0 | |
mapping_obj = self.client.read64(resource + MAPPING_OBJ_OFFSET) | |
data_off = self.client.read32(resource + RESOURCE_DATA_OFFSET_OFFSET) | |
if mapping_obj != 0: | |
data_array_base = self.client.read64(mapping_obj + RESOURCE_DATA_ARRAY_OFFSET) | |
if data_array_base != 0: | |
data_addr = self.client.read64(data_array_base + RESOURCE_ENTRY_SIZE * data_off) | |
return (resource, | |
data_addr, | |
self.client.read32(resource + RESOURCE_OFFSET_OFFSET), | |
self.client.read32(resource + RESOURCE_LENGTH_OFFSET), | |
self.client.read64(resource + RESOURCE_MBUF_OFFSET), | |
data_off) | |
def get_resources(self, verbose=False): | |
""" | |
Returns the information for each of the "resource IDs" currently in the resource array | |
""" | |
#Finding the resource array and size | |
pcie_obj = self.get_pcie_obj() | |
res_map = self.client.read64(pcie_obj + RESOURCE_MAP_OFFSET) | |
resource_array = self.client.read64(res_map + RESOURCE_ARRAY_OFFSET) | |
max_resource_id = (self.client.read32(res_map + MAX_RESOURCE_ID_OFFSET) & 0xFFFF) | |
if verbose: | |
print "Resource Array: %16X, Max Resource ID: %d" % (resource_array, max_resource_id) | |
#Dumping all resources | |
resource_array_data = self.client.read(resource_array, max_resource_id * QWORD_SIZE) | |
resources = [self.get_resource(resource_array_data, res_id) for res_id in range(0, max_resource_id)] | |
return filter(lambda x: x is not None, resources) | |
def get_dart(self, verbose=True): | |
""" | |
Finds the DART instance associated with the Broadcom Wi-Fi chip | |
""" | |
pcie_obj = self.get_pcie_obj() | |
iomapper_ptr = self.client.read64(pcie_obj + IO_MAPPER_OFFSET) | |
io_vm_allocator = self.client.read64(iomapper_ptr + IO_VM_ALLOCATOR_OFFSET) | |
sl_dart = self.client.read64(io_vm_allocator + SL_DART_OFFSET) | |
return DART(self.client, sl_dart, verbose) | |
def read_console(self): | |
""" | |
Reads the firmware's console. | |
""" | |
#Getting the firmware-resident log address | |
pciedev_shared_t_addr = self.fw_read32(self.ram_offset + self.ram_size - DWORD_SIZE) | |
console_addr = self.fw_read32(pciedev_shared_t_addr + 5*DWORD_SIZE) | |
log_addr = self.fw_read32(console_addr + 2*DWORD_SIZE) | |
log_size = self.fw_read32(console_addr + 3*DWORD_SIZE) | |
#Reading unaligned slack | |
log = "" | |
while log_addr % 16 != 0: | |
log_addr += DWORD_SIZE | |
log_size -= DWORD_SIZE | |
log += struct.pack("<I", self.fw_read32(log_addr)) | |
#Reading the rest | |
log_size -= log_size % 16 | |
log += self.fw_read(log_addr, log_size) | |
return log | |
def read_freelist(self): | |
""" | |
Reads the heap's freelist, returns a list of the form: [(chunk_addr, chunk_size),...] | |
""" | |
freelist_head = self.fw_read32(FREELIST_ADDR) | |
curr = freelist_head | |
freelist = [] | |
while curr != 0: | |
freelist.append((curr, self.fw_read32(curr))) | |
curr = self.fw_read32(curr + DWORD_SIZE) | |
if curr > (self.ram_offset + self.ram_size): | |
freelist.append((curr, GARBAGE_VALUE)) | |
break | |
return freelist | |
def dump_freelist(self): | |
""" | |
Prints each freechunk in the heap. | |
""" | |
freelist = self.read_freelist() | |
print "->".join(["(A %06X | S %05X)" % (addr, size) for (addr, size) in freelist]) | |
def hook(self, function_address, hook_content, hook_address): | |
""" | |
Inserts a hook onto the given function. The hook is placed at the given | |
address (so please make sure that it isn't occupied - e.g., near the top | |
of the heap). | |
""" | |
#Writing a THUMB2 wide branch to our hook | |
preamble = self.fw_read32(function_address) | |
next_word = self.fw_read32(function_address + DWORD_SIZE) | |
branch_to_hook = self.encode_thumb2_wide_branch(function_address, hook_address) | |
branch_back = self.encode_thumb2_wide_branch(hook_address + len(hook_content) + DWORD_SIZE, function_address + DWORD_SIZE) | |
#Writing the hook's contents | |
for i in range(0, len(hook_content), QWORD_SIZE): | |
self.fw_write64(hook_address + i, struct.unpack("<Q", hook_content[i:i+QWORD_SIZE])[0]) | |
#Writing the opcode + branch to the end of the hook | |
self.fw_write64(hook_address + len(hook_content), | |
struct.unpack("<Q", struct.pack("<I", preamble) + branch_back)[0]) | |
#Finally, inserting the hook itself | |
self.fw_write64(function_address, struct.unpack("<Q", branch_to_hook + struct.pack("<I", next_word))[0]) | |
def inject_frame(self, frame, num_injections=1): | |
""" | |
Injects the given frame directly from the firmware into the host, | |
repeating the given number of times. | |
""" | |
injection_chunk = open("code_chunks/send_frame/chunk.bin", "rb").read() | |
injection_chunk = injection_chunk.replace(struct.pack("<I", 0xF12A515E), struct.pack("<I", len(frame))) | |
injection_chunk = injection_chunk.replace(struct.pack("<I", 0xBEEFBEEF), struct.pack("<I", num_injections)) | |
injection_chunk = injection_chunk.replace(1024*"\xAB", frame + ("\xAB" * (1024 - len(frame)))) | |
self.execute_chunk(injection_chunk) | |
def dma_d2h(self, host_addr, dma_contents): | |
""" | |
Performs a DMA operation from the firmware to IO-Space (D2H). | |
""" | |
code_chunk = open("code_chunks/dma_d2h/chunk.bin", "rb").read() | |
code_chunk = code_chunk.replace(struct.pack("<I", 0xBEEF0101), struct.pack("<I", len(dma_contents))) | |
code_chunk = code_chunk.replace(struct.pack("<I", 0xBEEF0202), struct.pack("<I", host_addr & 0xFFFFFFFF)) | |
code_chunk = code_chunk.replace(struct.pack("<I", 0xBEEF0303), struct.pack("<I", (host_addr >> 32) & 0xFFFFFFFF)) | |
code_chunk = code_chunk.replace(128*"\xAB", dma_contents + ("\xAB" * (128 - len(dma_contents)))) | |
self.execute_chunk(code_chunk) | |
def encode_thumb2_wide_branch(self, from_addr, to_addr): | |
""" | |
Encodes an unconditional THUMB2 wide branch from the given address to the given address. | |
""" | |
if from_addr < to_addr: | |
s_bit = 0 | |
offset = to_addr - from_addr - THUMB2_INST_WIDTH | |
else: | |
s_bit = 1 | |
offset = 2**25 - (from_addr + THUMB2_INST_WIDTH - to_addr) | |
i1 = (offset >> 24) & 1 | |
i2 = (offset >> 23) & 1 | |
j1 = (0 if i1 else 1) ^ s_bit | |
j2 = (0 if i2 else 1) ^ s_bit | |
b2 = 0b11110000 | (s_bit << 2) | ((offset >> 20) & 0b11) | |
b1 = (offset >> 12) & 0xff | |
b4 = 0b10010000 | (j1 << 5) | (j2 << 3) | ((offset >> 9) & 0b111) | |
b3 = (offset >> 1) & 0xff | |
return chr(b1) + chr(b2) + chr(b3) + chr(b4) |