65 lines
2.5 KiB
Python
Executable file
65 lines
2.5 KiB
Python
Executable file
#!/usr/bin/env python3
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import sys
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if len(sys.argv) < 4:
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print("USAGE: mkfirm.py <kernel9.elf> <kernel11.elf> <output.firm>")
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print("WARNING: Currently you cannot install this FIRM, because YOU'LL BRICK YOUR 3DS!")
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sighax_sig = b'\x00'*256 #TODO insert sighax signature here.
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import struct
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import hashlib
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def get_elf_seg(f): #Return entry,section_beg,section_size,section
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f.seek(0)
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if f.read(4) != b"\x7FELF":
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raise Exception("Not an ELF file!")
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if f.read(1) != b"\x01":
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raise Exception("ELF64s are not supported!")
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if f.read(1) != b"\x01":
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raise Exception("Little Endian ELF required!")
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if f.read(1) != b"\x01":
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raise Exception("Unknown ELF version!")
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if struct.unpack("<H",f.read(2))[0] != 2:
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raise Exception("Invalid ELF format")
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if struct.unpack("<H",f.read(2))[0] != 0x28:
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raise Exception("This is not an ELF for ARM!")
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if struct.unpack("<I",f.read(4))[0] != 1:
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raise Exception("Unknown ELF version!")
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loadAddr = struct.unpack("<I",f.read(4))[0]
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phoff = struct.unpack("<I",f.read(4))[0]
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f.seek(0x2C)
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no_ent = struct.unpack("<H",f.read(2))[0]
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f.seek(phoff)
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section_begin = 0
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section_size = 0
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section = b''
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for ent in range(no_ent):
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if struct.unpack("<I",f.read(4)) != 1:
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continue
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off,vaddr,filesz,memsz=struct.unpack("<IIxxxxII",f.read(20))
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section_begin = vaddr
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section_size = memsz
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f.seek(off)
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section = f.read(filesz)
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section = section + b'\x00'*(memsz-filesz)
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break
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print("Loading section of size {} to {} with entrypoint {}".format(section_size,hex(section_begin),hex(loadAddr)))
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return (loadAddr,section_begin,section_size,section)
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f1 = open(sys.argv[1],"rb")
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f2 = open(sys.argv[2],"rb")
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f3 = open(sys.argv[3],"wb")
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arm9_entry,arm9_section_beg,arm9_section_size,arm9_section = get_elf_seg(f1)
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arm11_entry,arm11_section_beg,arm11_section_size,arm11_section = get_elf_seg(f2)
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arm9_hash=hashlib.sha256(arm9_section).digest()
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arm11_hash=hashlib.sha256(arm11_section).digest()
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arm9_off = 0x200
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arm11_off = 0x200+arm9_section_size
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f.write(b'FIRM')
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f.write(struct.pack("<III",0,arm11_entry,arm9_entry))
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f.write(b'\x00'*0x30)
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def write_seg(section_beg, section_size, hash, off):
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f.write(struct.pack("<IIII",off,section_beg,section_size,2))
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f.write(hash)
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write_seg(arm9_section_beg,arm9_section_size,arm9_hash,arm9_off)
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write_seg(arm11_section_beg,arm11_section_size,arm11_hash,arm11_off)
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f.write(b'\x00'*0x60)
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f.write(sighax_sig)
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f.write(arm9_section)
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f.write(arm11_section)
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