mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-05-19 14:28:06 +02:00
Kevin Thomas
84 lines
2.5 KiB
Python
84 lines
2.5 KiB
Python
"""
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Verify patched instruction and constant inside a UF2 file.
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Checks:
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- 0x10000410: should be 26 7a b4 ee (vsub.f32 s14, s14, s11)
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- 0x10000414: should be a6 7a b4 ee (vsub.f32 s15, s15, s11)
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- 0x1000042C: should be 00 00 00 41 (float 8.0)
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Usage:
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python verify_uf2.py build/hacked.uf2
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"""
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import sys
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import struct
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UF2_MAGIC_START0 = 0x0A324655 # "UF2\n"
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UF2_MAGIC_START1 = 0x9E5D5157
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UF2_MAGIC_END = 0x0AB16F30
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def load_uf2(path):
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blocks = []
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with open(path, "rb") as f:
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data = f.read()
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i = 0
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while i + 512 <= len(data):
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blk = data[i:i+512]
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(m0, m1, flags, tgt_addr, payload_size, block_no,
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num_blocks, file_size) = struct.unpack("<IIIIIIII", blk[:32])
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if m0 != UF2_MAGIC_START0 or m1 != UF2_MAGIC_START1:
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raise ValueError("Not a UF2 file or bad magic at block %d" % (i // 512))
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if payload_size != 256:
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raise ValueError("Unexpected payload size %d" % payload_size)
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if struct.unpack("<I", blk[512-4:512])[0] != UF2_MAGIC_END:
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raise ValueError("Bad end magic at block %d" % (i // 512))
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payload = blk[32:32+payload_size]
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blocks.append((tgt_addr, payload))
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i += 512
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return blocks
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def read_at(blocks, addr, length):
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"""Read 'length' bytes starting at virtual 'addr' from UF2 blocks."""
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out = bytearray()
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cur = addr
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while len(out) < length:
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# Find block that contains current address
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hit = None
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for base, pay in blocks:
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if base <= cur < base + len(pay):
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hit = (base, pay)
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break
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if not hit:
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# If missing, fill with 0xFF (flash default) and continue
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out.append(0xFF)
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cur += 1
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continue
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base, pay = hit
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out.append(pay[cur - base])
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cur += 1
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return bytes(out)
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def main():
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if len(sys.argv) != 2:
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print("Usage: python verify_uf2.py <path/to.uf2>")
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sys.exit(1)
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uf2_path = sys.argv[1]
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blocks = load_uf2(uf2_path)
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addrs = [0x10000410, 0x10000414, 0x1000042C]
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labels = ["@10000410", "@10000414", "@1000042C"]
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for label, a in zip(labels, addrs):
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bytes_ = read_at(blocks, a, 4)
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print(f"{label}: {bytes_.hex()} ", end="")
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if a == 0x1000042C:
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try:
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print(f"(float {struct.unpack('<f', bytes_)[0]:.6f})")
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except Exception:
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print("(not a valid float)")
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else:
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print()
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if __name__ == "__main__":
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main()
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