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#!/usr/bin/env python3
"""TA header fields +0x1c and +0x20 survive modification and still authenticate. Used or ignored?
Zeroing either still yields LOAD_TA status 0x0 on a signed image, so they are outside what the
signature covers (or are not checked). Both hold addresses in the image's own range
(+0x1c = 0x402000, +0x20 = 0x4011a0), so if they steer anything -- an entry point, a copy
destination -- an attacker controls it without forging a signature.
Test: set each to a range of values and see whether (a) the load still succeeds, and (b) the
loaded TA still behaves the same when invoked. A behaviour change means the field is CONSUMED.
"""
import glob, struct, sys, time
sys.path.insert(0,'/root/psp/hw')
from tinygrad import Device
import tinygrad.runtime.autogen.am.am as am
from ring_wrap import install
adev=Device["AMD"].iface.dev_impl; psp=adev.psp
submit=install(psp,adev)
base=open(glob.glob('/root/psp/contall/ta_42-0-0-6_1c874c3c*')[0],'rb').read()
def alloc(n):
pa=adev.mm.palloc(n,align=0x1000,zero=True,boot=False); return pa,adev.paddr2mc(pa)
def run(off,val,tag):
blob=bytearray(base)
if off is not None: struct.pack_into('<I',blob,off,val)
blob=bytes(blob)
ap_,amc=alloc(0x80000); cp,cmc=alloc(0x8000)
n=(len(blob)+3)&~3
adev.vram.view(ap_,n)[:]=blob+b'\x00'*(n-len(blob)); adev.gmc.flush_hdp()
c=am.struct_psp_gfx_cmd_resp(cmd_id=am.GFX_CMD_ID_LOAD_TA); t=c.cmd.cmd_load_ta
t.app_phy_addr_lo,t.app_phy_addr_hi=amc&0xFFFFFFFF,amc>>32; t.app_len=len(blob)
t.cmd_buf_phy_addr_lo,t.cmd_buf_phy_addr_hi=cmc&0xFFFFFFFF,cmc>>32; t.cmd_buf_len=0x4000
t0=time.time()
try: r=submit(c); st=r.resp.status&0xFFFFFFFF; sid=r.resp.session_id
except Exception as e:
try: st=int(str(e).strip().split()[-1])&0xFFFFFFFF
except Exception: st=-1
sid=None
dt=time.time()-t0
out=''
if st==0 and sid is not None and dt<5:
buf=bytearray(0x4000); struct.pack_into('<I',buf,0,1)
adev.vram.view(cp,0x4000)[:]=bytes(buf); adev.gmc.flush_hdp()
c=am.struct_psp_gfx_cmd_resp(cmd_id=am.GFX_CMD_ID_INVOKE_CMD)
iv=c.cmd.cmd_invoke_cmd; iv.session_id,iv.ta_cmd_id=sid,1
t1=time.time()
try: s=submit(c).resp.status&0xFFFFFFFF
except Exception as e:
try: s=int(str(e).strip().split()[-1])&0xFFFFFFFF
except Exception: s=-1
adev.gmc.flush_hdp()
out='invoke1=%#-10x %.1fs'%(s,time.time()-t1)
print(' %-30s load %#-11x %.1fs %s'%(tag,st,dt,out), flush=True)
return dt>5
run(None,0,'CONTROL unmodified')
for off in (0x1c,0x20):
for val,vn in ((0,'0'),(0x400100,'image base'),(0xDEADBEEF,'0xdeadbeef'),(0xFFFFFFFF,'ones')):
if run(off,val,'hdr[%#x]=%s'%(off,vn)): sys.exit(3)
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