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add_block_for_macho.py
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add_block_for_macho.py
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# this file is for extracting block structure for mach-o file
import idc
import idaapi
import re
def add_block_type():
# it's trouble to add c-style-structure directly into structure table, so we put them into local types instead
# ----------------------Block_descriptor--------------------------#
# flag with BLOCK_HAS_COPY_DISPOSE | BLOCK_HAS_SIGNATURE
strudef_Block_descriptor_hcd_hs = " \
typedef struct _Block_descriptor_hcd_hs \
{ \
uintptr_t reserved; \
uintptr_t size; \
void (*copy)(void *dst, const void *src); \
void (*dispose)(const void *); \
const char *signature; \
const char *layout; \
} Block_descriptor_hcd_hs; \
"
# flag with BLOCK_HAS_COPY_DISPOSE
strudef_Block_descriptor_hcd = " \
typedef struct _Block_descriptor_hcd \
{ \
uintptr_t reserved; \
uintptr_t size; \
void (*copy)(void *dst, const void *src); \
void (*dispose)(const void *); \
} Block_descriptor_hcd; \
"
# flag with BLOCK_HAS_SIGNATURE
strudef_Block_descriptor_hs = " \
typedef struct _Block_descriptor_hs \
{ \
uintptr_t reserved; \
uintptr_t size; \
const char *signature; \
const char *layout; \
} Block_descriptor_hs; \
"
# flag with none of above
strudef_Block_descriptor_o = " \
typedef struct _Block_descriptor_o \
{ \
uintptr_t reserved; \
uintptr_t size; \
const char *signature; \
const char *layout; \
} Block_descriptor_o; \
"
# origin structure
strudef_Block_descriptor = " \
typedef struct _Block_descriptor \
{ \
uintptr_t reserved; \
uintptr_t size; \
} Block_descriptor; \
"
# ----------------------Block_layout--------------------------#
strudef_Block_layout = " \
typedef struct _Block_layout \
{ \
void *isa; \
volatile int32_t flags; \
int32_t reserved; \
void (*invoke)(void *, ...); \
struct Block_descriptor *descriptor; \
} Block_layout; \
"
# now add two types above
SetLocalType(-1, "typedef unsigned long uintptr_t;typedef int int32_t;", 0)
SetLocalType(-1, strudef_Block_descriptor_hcd_hs, 0)
SetLocalType(-1, strudef_Block_descriptor_hcd, 0)
SetLocalType(-1, strudef_Block_descriptor_hs, 0)
SetLocalType(-1, strudef_Block_descriptor_o, 0)
SetLocalType(-1, strudef_Block_descriptor, 0)
SetLocalType(-1, strudef_Block_layout, 0)
# then add from local type to structures
SetType(0, "_Block_descriptor_hcd_hs") # address set to 0 just for import from localtypes into structures
SetType(0, "_Block_descriptor_hcd")
SetType(0, "_Block_descriptor_hs")
SetType(0, "_Block_descriptor_o")
SetType(0, "_Block_descriptor")
SetType(0, "_Block_layout")
global offset_flags, offset_invoke, offset_descri
tmpid = GetStrucIdByName("_Block_layout")
offset_flags = GetMemberOffset(tmpid, "flags")
offset_invoke = GetMemberOffset(tmpid, "invoke")
offset_descri = GetMemberOffset(tmpid, "descriptor")
if tmpid == -1 or offset_flags == -1 or offset_invoke == -1 or offset_descri == -1:
raise ValueError, "struct define error!"
def imp_cb(ea, name, ord):
global globalblock_addr, stackblock_addr
if name.find("NSConcreteGlobalBlock") != -1:
globalblock_addr = ea
elif name.find("NSConcreteStackBlock") != -1:
stackblock_addr = ea
return True
def find_xref(addr, xrefs, restriarea):
ref = DfirstB(addr)
while ref != BADADDR:
if SegName(ref) in restriarea:
xrefs.append(ref)
ref = DnextB(addr, ref)
def get_block_call():
# we tranverse import table and finally get two functions, which exists in libSystem.B.dylib
global globalblock_set, stackblock_set
nimps = idaapi.get_import_module_qty()
for i in xrange(0, nimps):
name = idaapi.get_import_module_name(i)
if name.find("libSystem.B.dylib") != -1:
idaapi.enum_import_names(i, imp_cb)
break
# then we find all xref to these two functions
if globalblock_addr != 0:
find_xref(globalblock_addr, globalblock_set, ["__const"])
if stackblock_addr != 0:
find_xref(stackblock_addr, stackblock_set, ["__text"])
def get_proto_for_sign(sign):
typemap = {'B': "bool", 'c': "bool", 'C': "unsigned char", 'd': "double", 'f': "float", 'i': "int",
'I': "unsigned int", 'l': "long", 'L': "long", 'q': "long long", 'Q': "unsigned long long",
's': "short", 'S': "unsigned short", 'v': "void"}
sl = len(sign)
descriarr = []
while True:
match = re.search(r'(?P<type>[^0-9]+)(?P<size>[0-9]+)', sign)
if match == None:
break
tmp1 = match.group("type")
tmp2 = match.group(0)
tmp3 = match.group("size")
descriarr.append({"type": tmp1, "off": int(tmp3)})
sign = sign[len(tmp2):]
for item in descriarr:
ch = item["type"][0]
ct = item["type"]
if ch in typemap:
if len(ct) != 1:
print "unknown type:", ct
item["type"] = typemap[ch]
elif ch == '{': # format as {MyClass=...
match = re.search(r'{([^=]+)=', ct)
if match == None:
print "unknown type:", ct
item["type"] = match.group(1)
elif ch == '@':
if ct == "@" or ct == "@?":
item["type"] = "id"
elif ct[1] == '"':
match = re.search(r'([0-9a-zA-Z_]+)', ct)
if match == None:
print "unknown type:", ct
item["type"] = match.group(1) + "*"
# detect if class defined
objtype = match.group(1)
print "init type:", objtype
SetType(0, objtype)
if BADADDR == GetStrucIdByName(objtype):
# we define a temporary type
SetLocalType(-1, "typedef struct " + objtype + " {void* isa;} _" + objtype + ";", 0)
else:
print "unknown type:", ct
item["type"] = "id"
elif ch == '^':
if len(ct) != 2 or ct[1] not in typemap:
print "unknown type:", ct
item["type"] = "void*"
else:
item["type"] = typemap[ct[1]]
resulttype = descriarr[0]["type"]
resulttype = resulttype + " func("
if len(descriarr) > 1:
for i in range(1, len(descriarr) - 1):
resulttype = resulttype + descriarr[i]["type"] + ","
resulttype = resulttype[0: len(resulttype) - 1]
resulttype = resulttype + ");"
return resulttype
def extract_description(addr, flag, funcaddr, descriaddr):
prototype = "void func(void);"
offset_copy = -1
offset_dispose = -1
offset_sign = -1
offset_layout = -1
if (flag & BLOCK_HAS_COPY_DISPOSE) != 0 and (flag & BLOCK_HAS_SIGNATURE) != 0:
MakeName(descriaddr, "block_descriptor_%x" % addr)
SetType(descriaddr, "_Block_descriptor_hcd_hs")
tmpid = GetStrucIdByName("_Block_descriptor_hcd_hs")
offset_copy = GetMemberOffset(tmpid, "copy")
offset_dispose = GetMemberOffset(tmpid, "dispose")
offset_sign = GetMemberOffset(tmpid, "signature")
offset_layout = GetMemberOffset(tmpid, "layout")
if is64bit:
copyaddr = Qword(descriaddr + offset_copy) & 0xFFFFFFFFFFFFFFFE # fixup thumb/arm
disposeaddr = Qword(descriaddr + offset_dispose) & 0xFFFFFFFFFFFFFFFE
signptr = Qword(descriaddr + offset_sign)
layoutptr = Qword(descriaddr + offset_layout)
else:
copyaddr = Dword(descriaddr + offset_copy) & 0xFFFFFFFE
disposeaddr = Dword(descriaddr + offset_dispose) & 0xFFFFFFFE
signptr = Dword(descriaddr + offset_sign)
layoutptr = Dword(descriaddr + offset_layout)
if signptr != 0:
prototype = get_proto_for_sign(GetString(signptr))
if layoutptr != 0:
pass
if copyaddr != 0:
MakeName(copyaddr, "block_copy_%x" % addr)
SetType(copyaddr, "void copy(void *dst, const void *src);")
if disposeaddr != 0:
MakeName(disposeaddr, "block_dispose_%x" % addr)
SetType(disposeaddr, "void dispose(const void *);")
if funcaddr > 0:
MakeName(funcaddr, "block_invoke_%x" % addr)
SetType(funcaddr, prototype)
elif (flag & BLOCK_HAS_COPY_DISPOSE) != 0:
MakeName(descriaddr, "block_descriptor_%x" % addr)
SetType(descriaddr, "_Block_descriptor_hcd")
tmpid = GetStrucIdByName("_Block_descriptor_hcd")
offset_copy = GetMemberOffset(tmpid, "copy")
offset_dispose = GetMemberOffset(tmpid, "dispose")
if is64bit:
copyaddr = Qword(descriaddr + offset_copy) & 0xFFFFFFFFFFFFFFFE # fixup thumb/arm
disposeaddr = Qword(descriaddr + offset_dispose) & 0xFFFFFFFFFFFFFFFE
else:
copyaddr = Dword(descriaddr + offset_copy) & 0xFFFFFFFE
disposeaddr = Dword(descriaddr + offset_dispose) & 0xFFFFFFFE
# print "addr=%x copy=%x dispose=%x" % (addr, copyaddr, disposeaddr)
if copyaddr != 0:
MakeName(copyaddr, "block_copy_%x" % addr)
SetType(copyaddr, "void copy(void *dst, const void *src);")
if disposeaddr != 0:
MakeName(disposeaddr, "block_dispose_%x" % addr)
SetType(disposeaddr, "void dispose(const void *);")
if funcaddr > 0:
MakeName(funcaddr, "block_invoke_%x" % addr)
SetType(funcaddr, prototype)
elif (flag & BLOCK_HAS_SIGNATURE) != 0:
MakeName(descriaddr, "block_descriptor_%x" % addr)
SetType(descriaddr, "_Block_descriptor_hs")
tmpid = GetStrucIdByName("_Block_descriptor_hs")
offset_sign = GetMemberOffset(tmpid, "signature")
offset_layout = GetMemberOffset(tmpid, "layout")
if is64bit:
signptr = Qword(descriaddr + offset_sign)
layoutptr = Qword(descriaddr + offset_layout)
else:
signptr = Dword(descriaddr + offset_sign)
layoutptr = Dword(descriaddr + offset_layout)
if signptr != 0:
prototype = get_proto_for_sign(GetString(signptr))
if layoutptr != 0:
pass
# print "addr=%x signptr=%s layoutptr=%x" % (addr, prototype, layoutptr)
if funcaddr > 0:
MakeName(funcaddr, "block_invoke_%x" % addr)
SetType(funcaddr, prototype)
else:
MakeName(descriaddr, "block_descriptor_%x" % addr)
SetType(descriaddr, "_Block_descriptor_o")
tmpid = GetStrucIdByName("_Block_descriptor_o")
# print "addr=%x" % addr
return prototype
def extract_globalblock(addr):
# this kind of block targetted to absolute address
print "------%x------" % addr
global offset_invoke, offset_flags, offset_descri
MakeName(addr, "global_block_%x" % addr)
SetType(addr, "_Block_layout")
flag = Dword(addr + offset_flags)
if is64bit:
funcaddr = Qword(addr + offset_invoke) & 0xFFFFFFFFFFFFFFFE # skip thumb or arm
descriaddr = Qword(addr + offset_descri)
else:
funcaddr = Dword(addr + offset_invoke) & 0xFFFFFFFE
descriaddr = Dword(addr + offset_descri)
prototype = "void func(void);"
if descriaddr != 0:
prototype = extract_description(addr, flag, funcaddr, descriaddr)
if funcaddr != 0:
MakeName(funcaddr, "global_block_invoke_%x" % addr)
SetType(funcaddr, prototype)
def extract_stackblock(addr):
# this kind of block targetted to stack address space
print "------%x------" % addr
# find the stack frame for this function
# which register store the base of current block structure
disasm = GetDisasm(addr)
bptreg = GetOpnd(addr, 0)
# find base stored position of current block in stack
begin = addr
for count in range(0, 20):
begin = begin + idaapi.decode_insn(begin)
if GetOpnd(begin, 0) == bptreg or GetOpnd(begin, 1) == bptreg:
break
# match "STR R1, [SP,#0x48+var_30]"
match = re.search(r'var_[0-9A-Fa-f]+', GetDisasm(begin))
if match == None: # too complex to handle
print "unhandled %x" % addr
return
varname = match.group(0)
frameid = GetFrame(addr)
varoff = GetMemberOffset(frameid, varname)
if varoff == -1:
print "unhandled %x" % addr
return
# first delete those members which occupy block space
new_name = "block_%x" % addr
id_Block_layout = GetStrucIdByName("_Block_layout")
size_Block_layout = GetStrucSize(id_Block_layout)
beginoff = varoff
endoff = varoff + size_Block_layout
for iaddr in range(beginoff, endoff):
DelStrucMember(frameid, iaddr)
if 0 != AddStrucMember(frameid, new_name, varoff, FF_STRU | FF_DATA, id_Block_layout, size_Block_layout):
print "unhandled %x" % addr
return
# get structure member data from decompiled source
funcaddr = 0
descriaddr = 0
flag = 0
lines = idaapi.decompile(addr).__str__().split('\n')
for line in lines:
line = line.lower()
if line.find(new_name) != -1:
if line.find(".flags") != -1:
if flag == 0:
match = re.search(r'flags = (.*);', line)
try:
flag = int(match.group(1)) & 0xffffffff # format as -1073741824
except:
flag = 0
elif line.find(".invoke") != -1:
if funcaddr == 0:
match = re.search(r'invoke = .*_([0-9a-f]+);', line)
try:
funcaddr = int(match.group(1), 16) & 0xfffffffffffffffe # fix thumb/arm
except:
funcaddr = 0
elif line.find(".descriptor") != -1:
if descriaddr == 0:
match = re.search(r'descriptor = .*_([0-9a-f]+);', line)
try:
descriaddr = int(match.group(1), 16)
except:
descriaddr = 0
if flag == 0 or descriaddr == 0:
print "unhandled %x" % addr
return
prototype = "void func(void);"
if descriaddr != 0:
prototype = extract_description(addr, flag, funcaddr, descriaddr)
if funcaddr != 0:
MakeName(funcaddr, "stack_block_invoke_%x" % addr)
SetType(funcaddr, prototype)
# constants
BLOCK_DEALLOCATING = 0x0001
BLOCK_REFCOUNT_MASK = 0xfffe
BLOCK_NEEDS_FREE = 1 << 24
BLOCK_HAS_COPY_DISPOSE = 1 << 25
BLOCK_HAS_CTOR = 1 << 26
BLOCK_IS_GC = 1 << 27
BLOCK_IS_GLOBAL = 1 << 28
BLOCK_USE_STRET = 1 << 29 # undefined if !BLOCK_HAS_SIGNATURE
BLOCK_HAS_SIGNATURE = 1 << 30
BLOCK_HAS_EXTENDED_LAYOUT = 1 << 31
# variables
globalblock_addr = 0
stackblock_addr = 0
globalblock_set = []
stackblock_set = []
is64bit = False
offset_flags = -1
offset_invoke = -1
offset_descri = -1
if __name__ == "__main__":
print "--------------init--------------"
if (GetCharPrm(INF_LFLAGS) & LFLG_64BIT) != 0:
is64bit = True
add_block_type()
get_block_call()
print "--------------extract_globalblock--------------"
for i in globalblock_set:
extract_globalblock(i)
print "--------------extract_stackblock--------------"
for i in stackblock_set:
extract_stackblock(i)