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#!/usr/bin/env python3
"""Derive an IDA symbol set for a PSP TA body: entry points + per-command handlers.
Feeds `idatui.drive syms <file.json>` (RPC `rename_many`), so a whole TA can be
annotated from static analysis instead of hand-navigation.
What it recovers, all from the layout established on HDCP in idatui:
* the five TEE entry points, via the **ARM-mode** trampoline (the rest of the image is
Thumb; decoding the trampoline as Thumb yields convincing garbage);
* the invoke dispatcher;
* the command -> handler map, from either dispatch form:
- `tbb`/`tbh` jump table, with the index base taken from the preceding
`sub rX, rY, #base` and the arm count from the `cmp rX, #n` bound;
- a `cmp #id` / `beq` chain.
Each arm/target is then scanned forward for the `bl` that does the work.
Ground truth check (`--selftest`): on HDCP 23.0.4.49 this must recover the dispatcher at
0x4013b4 and the command set {1..7,9,0xB,0xC,0xE,0xF,0x10,0x11,0x12,0x13} that was read
by hand out of the decompiler.
usage: ta_symbols.py <body.bin> --name <prefix> [-o syms.json]
ta_symbols.py --selftest
"""
import argparse
import json
import os
import re
import struct
import sys
import capstone as cs
BASE = 0x400100
MT = cs.Cs(cs.CS_ARCH_ARM, cs.CS_MODE_THUMB)
MA = cs.Cs(cs.CS_ARCH_ARM, cs.CS_MODE_ARM)
def sweep(b, start_va, end_va):
out, off, end = [], start_va - BASE, end_va - BASE
while off < min(end, len(b) - 2):
got = None
for i in MT.disasm(b[off:off + 4], BASE + off):
got = i
break
if got:
out.append(got)
off += got.size
else:
off += 2
return out
def header(b):
g = lambda o: struct.unpack_from('<I', b, o)[0]
return dict(base=g(0x04), entry=g(0x10), magic=b[0x14:0x18],
session_tbl=g(0x1c), guard=g(0x20))
def entry_points(b, h):
ins = list(MA.disasm(b[h['entry'] - BASE:h['entry'] - BASE + 0xC0], h['entry']))
seen, out = set(), []
for i in ins:
if i.mnemonic.startswith('ldr') and '[pc' in i.op_str:
m = re.search(r'#(-?0x[0-9a-f]+|-?\d+)', i.op_str.split('[pc')[1])
if not m:
continue
lit = ((i.address + 8) & ~3) + int(m.group(1), 0)
if 0 <= lit - BASE < len(b) - 4:
v = struct.unpack_from('<I', b, lit - BASE)[0] & ~1
if h['base'] < v < h['base'] + len(b) and v not in seen:
seen.add(v)
out.append(v)
return out
def first_call(b, va, span=0x28):
for i in sweep(b, va, va + span):
if i.mnemonic in ('bl', 'blx') and i.op_str.startswith('#'):
try:
return int(i.op_str[1:], 0)
except ValueError:
return None
return None
def dispatch_map(b, fn, span=0x800):
"""command id -> (arm_va, handler_va or None)."""
ins = sweep(b, fn, fn + span)
out = {}
for n, i in enumerate(ins):
if i.mnemonic in ('tbb', 'tbh'):
half = i.mnemonic == 'tbh'
# bound: nearest preceding cmp #n ; index base: nearest preceding sub #k
cnt, sub = None, 0
for k in range(n - 1, max(0, n - 12), -1):
p = ins[k]
if cnt is None and p.mnemonic.startswith('cmp') and '#' in p.op_str:
try:
cnt = int(p.op_str.split('#')[1], 0) + 1
except ValueError:
pass
if p.mnemonic in ('sub', 'sub.w', 'subw', 'subs') and '#' in p.op_str:
try:
sub = int(p.op_str.split('#')[1], 0)
break
except ValueError:
pass
if not cnt or cnt > 64:
continue
tb = i.address + 4
for k in range(cnt):
o = (tb + (2 * k if half else k)) - BASE
if o + 2 > len(b):
break
e = struct.unpack_from('<H', b, o)[0] if half else b[o]
arm = tb + 2 * e
out[sub + k] = (arm, first_call(b, arm))
if i.mnemonic.startswith('cmp') and '#' in i.op_str and n + 1 < len(ins):
nxt = ins[n + 1]
if nxt.mnemonic.startswith('b') and nxt.op_str.startswith('#') and \
nxt.mnemonic not in ('bl', 'blx', 'bx'):
try:
cid = int(i.op_str.split('#')[1], 0)
tgt = int(nxt.op_str[1:], 0)
except ValueError:
continue
if cid < 0x200 and cid not in out:
out[cid] = (tgt, first_call(b, tgt))
return out
def build(path, prefix):
b = open(path, 'rb').read()
h = header(b)
eps = entry_points(b, h)
syms, meta = [], dict(header=h, entry_points=eps, path=path)
labels = ['TA_CreateEntryPoint', 'TA_DestroyEntryPoint', 'TA_OpenSessionEntryPoint',
'TA_CloseSessionEntryPoint', 'TA_InvokeCommandEntryPoint']
syms.append(dict(addr=h['entry'], name='%s_entry_trampoline' % prefix))
for lab, ep in zip(labels, eps):
syms.append(dict(addr=ep, name='%s_%s' % (prefix, lab)))
cmds = {}
if len(eps) >= 5:
cmds = dispatch_map(b, eps[4])
# the dispatcher is often a thin wrapper; follow one level if it has a single call
if not cmds:
inner = first_call(b, eps[4], 0x40)
if inner:
cmds = dispatch_map(b, inner)
if cmds:
syms.append(dict(addr=inner, name='%s_dispatch' % prefix))
meta['inner_dispatch'] = inner
# Deliberately NOT naming command handlers here. The jump-table walk guesses
# the handler as "first bl after the arm", which is wrong whenever the arm sets
# up arguments or falls through, and those wrong names then persist in the IDB
# and shadow the decompiler-derived map. fw/annotate_ta.py owns command naming.
meta['commands'] = {hex(k): (hex(v[0]), hex(v[1]) if v[1] else None)
for k, v in sorted(cmds.items())}
# de-duplicate: IDA rejects a repeated name
seen, uniq = set(), []
for s in syms:
if s['addr'] in seen:
continue
seen.add(s['addr'])
uniq.append(s)
return uniq, meta
def selftest():
p = 'psp_out/versions_win/ta_0.7.0.1_543e8a45.bin'
if not os.path.exists(p):
print('selftest: HDCP reference body missing')
return 1
syms, meta = build(p, 'hdcp')
inv = [s for s in syms if s['name'].endswith('InvokeCommandEntryPoint')]
want = {1, 2, 3, 4, 5, 6, 7, 9, 0xB, 0xC, 0xE, 0xF, 0x10, 0x11, 0x12, 0x13}
got = {int(k, 16) for k in meta['commands']}
ok_inv = inv and inv[0]['addr'] == 0x4013b4
missing = want - got
print('selftest HDCP 23.0.4.49:')
print(' invoke entry %s (want 0x4013b4) -> %s'
% (hex(inv[0]['addr']) if inv else None, 'OK' if ok_inv else 'FAIL'))
print(' commands recovered: %s' % sorted(hex(x) for x in got))
print(' hand-read set covered: %s' % ('OK' if not missing else
'MISSING %s' % sorted(hex(x) for x in missing)))
return 0 if (ok_inv and not missing) else 1
def main():
ap = argparse.ArgumentParser()
ap.add_argument('body', nargs='?')
ap.add_argument('--name', default='ta')
ap.add_argument('-o', '--out')
ap.add_argument('--selftest', action='store_true')
a = ap.parse_args()
if a.selftest:
return selftest()
syms, meta = build(a.body, a.name)
if a.out:
json.dump(syms, open(a.out, 'w'), indent=1)
json.dump(meta, open(a.out.replace('.json', '.meta.json'), 'w'),
indent=1, default=str)
print(json.dumps(meta['commands'], indent=1))
print('%d symbols' % len(syms))
return 0
if __name__ == '__main__':
raise SystemExit(main())
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