Source file loader_pe.ml
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
open Basic_types.Integers
open Reader
open Loader_types
let read_magic t =
(not (dim t < 0x40))
&& Uint8.to_char (Read.u8 t) = 'M'
&& Uint8.to_char (Read.u8 t) = 'Z'
&&
(set_pos t 0x3c;
set_pos t (Uint32.to_int (Read.u32 t));
(not (get_pos t + 4 > dim t))
&& Uint8.to_char (Read.u8 t) = 'P'
&& Uint8.to_char (Read.u8 t) = 'E'
&& Uint8.to_char (Read.u8 t) = '\x00'
&& Uint8.to_char (Read.u8 t) = '\x00')
let check_magic buffer =
let t = of_bigarray buffer in
read_magic t
let init_cursor buffer =
let t = of_bigarray buffer in
if not (read_magic t) then invalid_format "No PE magic number";
t
let arch = function
| 0x014c -> Machine.x86
| 0x01c0 -> Machine.armv7 Machine.LittleEndian
| 0x8664 -> Machine.amd64
| _ -> Machine.unknown
let t =
ensure t 20 "File header truncated";
let machine = Read.u16 t in
let number_of_sections = Uint16.to_int (Read.u16 t) in
let time_date_stamp = Read.u32 t in
let pointer_to_symbol_table = Uint32.to_int (Read.u32 t) in
let number_of_symbols = Uint32.to_int (Read.u32 t) in
let = Uint16.to_int (Read.u16 t) in
let characteristics = Read.u16 t in
{
machine;
number_of_sections;
time_date_stamp;
pointer_to_symbol_table;
number_of_symbols;
size_of_optional_header;
characteristics;
}
type standard_fields = {
magic : u16;
size_of_code : u32;
size_of_initialized_data : u32;
size_of_uninitialized_data : u32;
address_of_entry_point : Virtual_address.t;
base_of_code : u32;
base_of_data : u32 option;
}
type windows_fields = {
image_base : Virtual_address.t;
section_alignement : u32;
file_alignement : u32;
size_of_image : u32;
size_of_headers : u32;
checksum : u32;
subsystem : u16;
dll_characteristics : u16;
size_of_stack_reserve : u64;
size_of_stack_commit : u64;
size_of_heap_reserve : u64;
size_of_heap_commit : u64;
number_of_rva_and_sizes : u32;
}
type data_directory = { virtual_address : u32; size : u32 }
type data_directories = {
export_directory : data_directory;
import_directory : data_directory;
resource_directory : data_directory;
exception_directory : data_directory;
security_directory : data_directory;
basereloc_directory : data_directory;
debug_directory : data_directory;
globalptr_directory : data_directory;
tls_directory : data_directory;
load_config_directory : data_directory;
bound_import_directory : data_directory;
iat_directory : data_directory;
delay_import_directory : data_directory;
clr_header_directory : data_directory;
}
type program = file_header * optional_header
let read_standard_fields32 t magic =
ensure t 26 "Standard fields truncated";
let _major_linker_version = Read.u8 t in
let _minor_linker_version = Read.u8 t in
let size_of_code = Read.u32 t in
let size_of_initialized_data = Read.u32 t in
let size_of_uninitialized_data = Read.u32 t in
let address_of_entry_point = Virtual_address.of_uint32 (Read.u32 t) in
let base_of_code = Read.u32 t in
let base_of_data = Some (Read.u32 t) in
{
magic;
size_of_code;
size_of_initialized_data;
size_of_uninitialized_data;
address_of_entry_point;
base_of_code;
base_of_data;
}
let read_standard_fields64 t magic =
ensure t 22 "Standard fields truncated";
let _major_linker_version = Read.u8 t in
let _minor_linker_version = Read.u8 t in
let size_of_code = Read.u32 t in
let size_of_initialized_data = Read.u32 t in
let size_of_uninitialized_data = Read.u32 t in
let address_of_entry_point = Virtual_address.of_uint32 (Read.u32 t) in
let base_of_code = Read.u32 t in
let base_of_data = None in
{
magic;
size_of_code;
size_of_initialized_data;
size_of_uninitialized_data;
address_of_entry_point;
base_of_code;
base_of_data;
}
let read_standard_fields t =
ensure t 2 "PE magic number truncated";
let magic = Read.u16 t in
match Uint16.to_int magic with
| 0x10b -> read_standard_fields32 t magic
| 0x20b -> read_standard_fields64 t magic
| _ -> invalid_format "Invalid PE image file"
let read_windows_fields32 t =
ensure t 68 "Windows fields truncated";
let image_base = Virtual_address.of_uint32 (Read.u32 t) in
let section_alignement = Read.u32 t in
let file_alignement = Read.u32 t in
let _major_os_version = Read.u16 t in
let _minor_os_version = Read.u16 t in
let _major_image_version = Read.u16 t in
let _minor_image_version = Read.u16 t in
let _major_subsystem_version = Read.u16 t in
let _minor_subsystem_version = Read.u16 t in
if not (Read.i32 t = 0l) then invalid_format "Invalid Win32 version value";
let size_of_image = Read.u32 t in
let = Read.u32 t in
let checksum = Read.u32 t in
let subsystem = Read.u16 t in
let dll_characteristics = Read.u16 t in
let size_of_stack_reserve = Uint32.to_uint64 (Read.u32 t) in
let size_of_stack_commit = Uint32.to_uint64 (Read.u32 t) in
let size_of_heap_reserve = Uint32.to_uint64 (Read.u32 t) in
let size_of_heap_commit = Uint32.to_uint64 (Read.u32 t) in
if not (Read.i32 t = 0l) then invalid_format "Invalid loader flags";
let number_of_rva_and_sizes = Read.u32 t in
{
image_base;
section_alignement;
file_alignement;
size_of_image;
size_of_headers;
number_of_rva_and_sizes;
checksum;
subsystem;
dll_characteristics;
size_of_stack_reserve;
size_of_stack_commit;
size_of_heap_reserve;
size_of_heap_commit;
}
let read_windows_fields64 t =
ensure t 88 "Windows fields truncated";
let image_base = Virtual_address.of_uint64 (Read.u64 t) in
let section_alignement = Read.u32 t in
let file_alignement = Read.u32 t in
let _major_os_version = Read.u16 t in
let _minor_os_version = Read.u16 t in
let _major_image_version = Read.u16 t in
let _minor_image_version = Read.u16 t in
let _major_subsystem_version = Read.u16 t in
let _minor_subsystem_version = Read.u16 t in
if not (Read.i32 t = 0l) then invalid_format "Invalid Win32 version value";
let size_of_image = Read.u32 t in
let = Read.u32 t in
let checksum = Read.u32 t in
let subsystem = Read.u16 t in
let dll_characteristics = Read.u16 t in
let size_of_stack_reserve = Read.u64 t in
let size_of_stack_commit = Read.u64 t in
let size_of_heap_reserve = Read.u64 t in
let size_of_heap_commit = Read.u64 t in
if not (Read.i32 t = 0l) then invalid_format "Invalid loader flags";
let number_of_rva_and_sizes = Read.u32 t in
{
image_base;
section_alignement;
file_alignement;
size_of_image;
size_of_headers;
number_of_rva_and_sizes;
checksum;
subsystem;
dll_characteristics;
size_of_stack_reserve;
size_of_stack_commit;
size_of_heap_reserve;
size_of_heap_commit;
}
let read_windows_fields standard t =
match Uint16.to_int standard.magic with
| 0x10b -> read_windows_fields32 t
| 0x20b -> read_windows_fields64 t
| _ -> invalid_format "Invalid PE image file"
let read_data_directory t =
ensure t 8 "Data directory truncated";
let virtual_address = Read.u32 t in
let size = Read.u32 t in
{ virtual_address; size }
let read_data_directories t =
ensure t 96 "Data directories truncated";
let export_directory = read_data_directory t in
let import_directory = read_data_directory t in
let resource_directory = read_data_directory t in
let exception_directory = read_data_directory t in
let security_directory = read_data_directory t in
let basereloc_directory = read_data_directory t in
let debug_directory = read_data_directory t in
if not (Read.i64 t = 0L) then invalid_format "Invalid data directories";
let globalptr_directory = read_data_directory t in
if not (Uint32.to_int32 globalptr_directory.size = 0l) then
invalid_format "Invalid data directories";
let tls_directory = read_data_directory t in
let load_config_directory = read_data_directory t in
let bound_import_directory = read_data_directory t in
let iat_directory = read_data_directory t in
let delay_import_directory = read_data_directory t in
let = read_data_directory t in
if not (Read.i64 t = 0L) then invalid_format "Invalid data directories";
{
export_directory;
import_directory;
resource_directory;
exception_directory;
security_directory;
basereloc_directory;
debug_directory;
globalptr_directory;
tls_directory;
load_config_directory;
bound_import_directory;
iat_directory;
delay_import_directory;
clr_header_directory;
}
let t =
let standard_fields = read_standard_fields t in
let windows_fields = read_windows_fields standard_fields t in
let data_directories = read_data_directories t in
{ standard_fields; windows_fields; data_directories }
let rebase o i = Virtual_address.add o.windows_fields.image_base i
type section = {
section_name : string;
virtual_size : u32;
virtual_address : Virtual_address.t;
size_of_raw_data : int;
pointer_to_raw_data : int;
characteristics : u32;
}
let read_section_name t =
let name = Peek.fixed_string t 8 in
advance t 8;
name
let read_section t file optional n =
set_pos t (optional + file.size_of_optional_header + (n * 40));
ensure t 40 "Section header truncated";
let section_name = read_section_name t in
let virtual_size = Read.u32 t in
let virtual_address = Virtual_address.of_uint32 (Read.u32 t) in
let size_of_raw_data = Uint32.to_int (Read.u32 t) in
let pointer_to_raw_data = Uint32.to_int (Read.u32 t) in
let _pointer_to_relocations = Read.u32 t in
let _pointer_to_linenumbers = Read.u32 t in
let _number_of_relocations = Read.u16 t in
let _number_of_linenumbers = Read.u16 t in
let characteristics = Read.u32 t in
{
section_name;
virtual_size;
virtual_address;
size_of_raw_data;
pointer_to_raw_data;
characteristics;
}
let read_sections t file optional =
Array.init file.number_of_sections (read_section t file optional)
exception Found of section
let find_section sections f =
try
Array.iter (fun section -> if f section then raise (Found section)) sections;
None
with Found section -> Some section
let in_section optional (section : section) addr =
addr >= rebase optional section.virtual_address
&& addr
< Virtual_address.add_bigint
(Uint32.to_bigint section.virtual_size)
(rebase optional section.virtual_address)
let in_section_opt optional section_opt addr =
match section_opt with
| None -> false
| Some section -> in_section optional section addr
let find_section_by_addr optional sections addr =
find_section sections (fun s -> in_section optional s addr)
type symbol = {
symbol_name : string;
value : Virtual_address.t;
section_number : u16;
storage_class : u8;
number_of_aux_symbols : u8;
}
let read_symbol_name t strtab strsize =
let position = get_pos t in
let name =
if Read.i32 t = 0l then (
let n = Uint32.to_int (Read.u32 t) in
set_pos t (strtab + n);
Read.zero_string "Unterminated symbol name" t ~maxlen:(strsize - n) ())
else (
set_pos t position;
Read.fixed_string t 8)
in
set_pos t (position + 8);
name
let read_symbol t file strtab strsize n =
set_pos t (file.pointer_to_symbol_table + (n * 18));
ensure t 18 "Symbol header truncated";
let symbol_name = read_symbol_name t strtab strsize in
let value = Virtual_address.of_uint32 (Read.u32 t) in
let section_number = Read.u16 t in
let storage_class = Read.u8 t in
let number_of_aux_symbols = Read.u8 t in
{ symbol_name; value; section_number; storage_class; number_of_aux_symbols }
let read_symbols t file =
let strtab = file.pointer_to_symbol_table + (18 * file.number_of_symbols) in
let strsize =
set_pos t strtab;
Uint32.to_int (Read.u32 t)
in
set_pos t file.pointer_to_symbol_table;
Array.init file.number_of_symbols (read_symbol t file strtab strsize)
module Section = struct
type t = optional_header * section
let name (_, s) = s.section_name
let flag ((_, s) : t) = Uint32.to_int32 s.characteristics
let pos (o, (s : section)) =
{ raw = s.pointer_to_raw_data; virt = rebase o s.virtual_address }
let size (_, s) =
{ raw = s.size_of_raw_data; virt = Uint32.to_bigint s.virtual_size }
let (_, s) = s
let has_flag f s =
let mask =
match f with
| Write -> 0x80000000l
| Read -> 0x40000000l
| Exec -> 0x20000000l
in
Int32.logand (flag s) mask = mask
end
module Symbol = struct
type t = symbol
let name s = s.symbol_name
let value s = s.value
let s = s
end
let pp_symbol ppf symbol =
Format.fprintf ppf "@[<h>%s %s@]"
(Z.format "%-8x" (Virtual_address.to_bigint (Symbol.value symbol)))
(Symbol.name symbol)
let pp_symbols ppf symbols =
let nsymbols = Array.length symbols in
if nsymbols <> 0 then
Format.fprintf ppf "@[<v 2># Symbols (%d) @ %a@]" nsymbols
(fun ppf a ->
Array.iter (fun sy -> Format.fprintf ppf "%a@ " pp_symbol sy) a)
symbols
let pp_section i ppf section =
let aux fmt section (f, s) =
Format.fprintf fmt "%s" (if Section.has_flag f section then s else "-")
in
let pp_flags fmt section =
List.iter (aux fmt section)
Loader_types.[ (Read, "r"); (Write, "w"); (Exec, "x") ]
in
let pp_imap ppf m =
Format.fprintf ppf "@[<h>%8x %s@]" m.Loader_types.raw
(Z.format "%8x" m.Loader_types.virt)
in
let pos = Section.pos section in
Format.fprintf ppf "@[<h>%2d %-20s %8lx %8x %s %a %a@]" i
(Section.name section) (Section.flag section) pos.raw
(Z.format "%8x" (Virtual_address.to_bigint pos.virt))
pp_imap (Section.size section) pp_flags section
let pp_sections ppf sections =
let nsections = Array.length sections in
if nsections <> 0 then
Format.fprintf ppf "@[<v 2># Sections (%d)@ %a@]" nsections
(fun ppf a ->
Array.iteri (fun i sy -> Format.fprintf ppf "%a@ " (pp_section i) sy) a)
sections
let pp_arch ppf arch = Format.fprintf ppf "@[Machine: %a@]" Machine.pp arch
let pp_ep ppf ep =
Format.fprintf ppf "@[Entry point address: %a@]" Virtual_address.pp ep
module Img = struct
type t = program * section array * symbol array * buffer
let arch ((f, _), _, _, _) = arch (Uint16.to_int f.machine)
let entry ((_, o), _, _, _) =
rebase o o.standard_fields.address_of_entry_point
let sections ((_, o), s, _, _) = Array.map (fun s -> (o, s)) s
let symbols (_, _, s, _) = Array.copy s
let (h, _, _, _) = h
let cursor ?at (_, _, _, b) = Reader.of_bigarray ?pos:at b
let content (_, _, _, b) (_, s) =
Bigarray.Array1.sub b s.pointer_to_raw_data s.size_of_raw_data
let buffer (_, _, _, b) = b
let ppf img =
Format.fprintf ppf "@[<v 2># Header@ %a@ %a@]" pp_arch (arch img) pp_ep
(entry img)
let pp ppf img =
Format.fprintf ppf "@[<v 0>%a@ %a@ %a@]" pp_header img pp_symbols
(symbols img) pp_sections (sections img)
end
let load buffer =
let t = init_cursor buffer in
let = read_file_header t in
let position = get_pos t in
let = read_optional_header t in
let sections = read_sections t file_header position in
let symbols = read_symbols t file_header in
((file_header, optional_header), sections, symbols, buffer)
let load_file_descr file_descr =
let buffer =
Bigarray.(
array1_of_genarray
(Unix.map_file file_descr Int8_unsigned C_layout false [| -1 |]))
in
load buffer
let load_file path =
let file_descr = Unix.openfile path [ Unix.O_RDONLY ] 0 in
let img = load_file_descr file_descr in
Unix.close file_descr;
img
let read_offset (_, _, _, b) offset = Int.unsafe_to_uint8 b.{offset}
let cache = ref None
let find_section_by_addr_with_cache optional sections addr =
if not (in_section_opt optional !cache addr) then
cache := find_section_by_addr optional sections addr;
!cache
let read_address ((_, o), s, _, b) addr =
match find_section_by_addr_with_cache o s addr with
| None ->
let msg =
Format.asprintf "Unreachable virtual address %a" Virtual_address.pp addr
in
invalid_arg msg
| Some (s : section) ->
let offset = Virtual_address.diff addr (rebase o s.virtual_address) in
if offset >= s.size_of_raw_data then Int.unsafe_to_uint8 0
else Int.unsafe_to_uint8 b.{offset + s.pointer_to_raw_data}