mirror of
https://github.com/Alex313031/thorium.git
synced 2025-01-09 11:27:32 -03:00
305 lines
9.4 KiB
Python
305 lines
9.4 KiB
Python
"""
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MIT License
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Copyright (c) 2023 David Buchanan
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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This is widevine_fixup.py version 0.1. Find the latest version here:
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https://gist.github.com/DavidBuchanan314/c6b97add51b97e4c3ee95dc890f9e3c8
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"""
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import sys
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if len(sys.argv) != 3:
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print(f"Usage: {sys.argv[0]} input.so output.so")
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exit()
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"""
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aarch64 widevine builds currently only support 4k page sizes.
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This script fixes that, by pre-padding the LOAD segments so that they meet
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the alignment constraints required by the loader, and then fixing up the
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relevant header offsets to keep the file valid.
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It also injects two functions that are not exported from arch's libgcc, into
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the empty space at the end of the .text segment. This avoids any LD_PRELOAD
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workarounds. (The injected functions are __aarch64_ldadd4_acq_rel
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and __aarch64_swp4_acq_rel)
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This script is tested against aarch64 libwidevinecdm.so version 4.10.2557.0, with
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BuildID b71fd3342a03fdb140e1f7a757960df219d63625 and sha256sum
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42ddbedb40f079a1dd63147456c12eb1ee0e986a0cd1a8b26e57ad9d119adbb4
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You can conveniently obtain it, and all dependencies, by installing
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https://aur.archlinux.org/packages/widevine-aarch64
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This process is fragile, and may not work as-is on future revisions of widevine.
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IMPORTANT NOTE: On systems with >4k page size (e.g. Apple Silicon devices),
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Using the patched binary *significantly* weakens the security of your web browser,
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in two ways. Firstly, it disables the RELRO security mitigation, and secondly it
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creates a RWX mapping.
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I'm looking into ways around this, but it will require more advanced patching.
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P.S. If you want to watch Netflix, you will need to spoof a ChromeOS useragent
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"""
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import ctypes
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class Elf64_Ehdr(ctypes.Structure):
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_fields_ = [
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('e_ident', ctypes.c_ubyte * 16),
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('e_type', ctypes.c_uint16),
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('e_machine', ctypes.c_uint16),
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('e_version', ctypes.c_uint32),
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('e_entry', ctypes.c_uint64),
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('e_phoff', ctypes.c_uint64),
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('e_shoff', ctypes.c_uint64),
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('e_flags', ctypes.c_uint32),
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('e_ehsize', ctypes.c_uint16),
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('e_phentsize', ctypes.c_uint16),
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('e_phnum', ctypes.c_uint16),
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('e_shentsize', ctypes.c_uint16),
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('e_shnum', ctypes.c_uint16),
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('e_shstrndx', ctypes.c_uint16),
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]
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class Elf64_Phdr(ctypes.Structure):
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_fields_ = [
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('p_type', ctypes.c_uint32),
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('p_flags', ctypes.c_uint32),
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('p_offset', ctypes.c_uint64),
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('p_vaddr', ctypes.c_uint64),
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('p_paddr', ctypes.c_uint64),
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('p_filesz', ctypes.c_uint64),
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('p_memsz', ctypes.c_uint64),
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('p_align', ctypes.c_uint64),
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]
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class P_FLAGS:
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""" Flag values for the p_flags field of program headers
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"""
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PF_X=0x1
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PF_W=0x2
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PF_R=0x4
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PF_MASKOS=0x00FF0000
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PF_MASKPROC=0xFF000000
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class PT:
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PT_NULL=0
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PT_LOAD=1
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PT_DYNAMIC=2
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PT_INTERP=3
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PT_NOTE=4
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PT_SHLIB=5
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PT_PHDR=6
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PT_TLS=7
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PT_LOOS=0x60000000
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PT_HIOS=0x6fffffff
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PT_GNU_EH_FRAME=0x6474e550
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PT_GNU_STACK=0x6474e551
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PT_GNU_RELRO=0x6474e552
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PT_GNU_PROPERTY=0x6474e553
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class Elf64_Shdr(ctypes.Structure):
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_fields_ = [
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('sh_name', ctypes.c_uint32),
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('sh_type', ctypes.c_uint32),
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('sh_flags', ctypes.c_uint64),
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('sh_addr', ctypes.c_uint64),
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('sh_offset', ctypes.c_uint64),
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('sh_size', ctypes.c_uint64),
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('sh_link', ctypes.c_uint32),
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('sh_info', ctypes.c_uint32),
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('sh_addralign', ctypes.c_uint64),
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('sh_entsize', ctypes.c_uint64),
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]
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class Elf64_Sym(ctypes.Structure):
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_fields_ = [
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('st_name', ctypes.c_uint32),
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('st_info', ctypes.c_ubyte),
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('st_other', ctypes.c_ubyte),
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('st_shndx', ctypes.c_uint16),
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('st_value', ctypes.c_uint64),
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('st_size', ctypes.c_uint64),
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]
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class Elf64_Dyn(ctypes.Structure):
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_fields_ = [
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('d_tag', ctypes.c_uint64),
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('d_val', ctypes.c_uint64), # union with d_ptr
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]
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class D_TAG: # XXX: this is very incomplete
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DT_NULL=0
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DT_NEEDED=1
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DT_SONAME=14
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class Elf64_Rela(ctypes.Structure):
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_fields_ = [
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('r_offset', ctypes.c_uint64),
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#('r_info', ctypes.c_uint64),
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('r_type', ctypes.c_uint32),
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('r_symbol', ctypes.c_uint32),
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('r_addend', ctypes.c_int64),
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]
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import mmap
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TARGET_PAGE_SIZE = 0x4000
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WEAKEN_SECURITY = mmap.PAGESIZE > 0x1000
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inject_addr = None
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if WEAKEN_SECURITY:
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print("It looks like you're running Asahi, or some other device with >4k page size.")
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print("We will need to weaken certain memory permissions accordingly.")
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"""
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0000000000000b24 <__aarch64_ldadd4_acq_rel>:
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b24: 2a0003e2 mov w2, w0
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b28: 885ffc20 ldaxr w0, [x1]
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b2c: 0b020003 add w3, w0, w2
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b30: 8804fc23 stlxr w4, w3, [x1]
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b34: 35ffffa4 cbnz w4, b28 <__aarch64_ldadd4_acq_rel+0x4>
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b38: d65f03c0 ret
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0000000000000b3c <__aarch64_swp4_acq_rel>:
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b3c: 2a0003e2 mov w2, w0
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b40: 885ffc20 ldaxr w0, [x1]
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b44: 8803fc22 stlxr w3, w2, [x1]
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b48: 35ffffc3 cbnz w3, b40 <__aarch64_swp4_acq_rel+0x4>
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b4c: d65f03c0 ret
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"""
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injected_code = bytes.fromhex("e203002a20fc5f880300020b23fc0488a4ffff35c0035fd6e203002a20fc5f8822fc0388c3ffff35c0035fd6")
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with open(sys.argv[1], "rb") as infile:
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elf = bytearray(infile.read())
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elf_length = len(elf)
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elf += bytearray(0x100000) # pre-expand the buffer by more than enough
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ehdr = Elf64_Ehdr.from_buffer(elf)
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phdrs = [
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Elf64_Phdr.from_buffer(memoryview(elf)[ehdr.e_phoff + i * ehdr.e_phentsize:])
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for i in range(ehdr.e_phnum)
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]
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adjustments = []
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def adjust_offset(x):
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for index, delta in adjustments:
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if x >= index:
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x += delta
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return x
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for phdr in phdrs:
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phdr.p_offset = adjust_offset(phdr.p_offset)
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if phdr.p_type == PT.PT_LOAD:
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phdr.p_align = TARGET_PAGE_SIZE
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delta_needed = (phdr.p_vaddr - phdr.p_offset) % phdr.p_align
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if delta_needed:
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print(f"inserting {hex(delta_needed)} bytes at offset {hex(phdr.p_offset)}")
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if not inject_addr:
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pad_bytes = injected_code + bytes(delta_needed - len(injected_code))
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inject_addr = phdr.p_offset
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print(f"also injecting code at offset {hex(phdr.p_offset)}")
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else:
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pad_bytes = bytes(delta_needed)
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elf[phdr.p_offset:] = pad_bytes + elf[phdr.p_offset:-delta_needed]
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adjustments.append((phdr.p_offset, delta_needed))
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elf_length += delta_needed
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phdr.p_offset += delta_needed
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if WEAKEN_SECURITY:
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phdr.p_flags |= P_FLAGS.PF_X # XXX: this is a hack!!! (at the very least, we should apply it only to the mappings that need it)
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if WEAKEN_SECURITY and phdr.p_type == PT.PT_GNU_RELRO:
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print("neutering relro") # XXX: relro is a security mechanism
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phdr.p_type = PT.PT_NOTE
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# the section headers have moved
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ehdr.e_shoff = adjust_offset(ehdr.e_shoff)
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shdrs = [
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Elf64_Shdr.from_buffer(memoryview(elf)[ehdr.e_shoff + i * ehdr.e_shentsize:])
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for i in range(ehdr.e_shnum)
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]
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for shdr in shdrs:
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shdr.sh_offset = adjust_offset(shdr.sh_offset)
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strtab = shdrs[ehdr.e_shstrndx]
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def resolve_string(elf, strtab, stridx, count=False):
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if count:
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str_start = strtab.sh_offset
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for _ in range(stridx):
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str_start = elf.index(b"\0", str_start) + 1
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else:
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str_start = strtab.sh_offset + stridx
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str_end = elf.index(b"\0", str_start)
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return bytes(elf[str_start:str_end])
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shdr_by_name = {
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resolve_string(elf, strtab, shdr.sh_name): shdr
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for shdr in shdrs
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}
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# XXX: unfortunately this does not do anything useful!
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# It doesn't hurt either, so I'm leaving it here just in case.
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dynsym = shdr_by_name[b".dynsym"]
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dynstr = shdr_by_name[b".dynstr"]
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for i in range(0, dynsym.sh_size, dynsym.sh_entsize):
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sym = Elf64_Sym.from_buffer(memoryview(elf)[dynsym.sh_offset + i:])
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name = resolve_string(elf, dynstr, sym.st_name)
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if name in [b"__aarch64_ldadd4_acq_rel", b"__aarch64_swp4_acq_rel"]:
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print(f"weak binding {name}")
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sym.st_info = (sym.st_info & 0x0f) | (2 << 4) # STB_WEAK
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"""
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dynamic = shdr_by_name[b".dynamic"]
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for i in range(0, dynamic.sh_size, dynamic.sh_entsize):
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dyn = Elf64_Dyn.from_buffer(memoryview(elf)[dynamic.sh_offset + i:])
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if dyn.d_tag == D_TAG.DT_SONAME:
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print("hijacking SONAME tag to point to NEEDED libgcc_hide.so")
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dyn.d_tag = D_TAG.DT_NEEDED
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dyn.d_val = inject_addr - dynstr.sh_offset
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dynstr.sh_size = (inject_addr - dynstr.sh_offset) + len(PATH_TO_INJECT) + 1
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"""
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rela_plt = shdr_by_name[b".rela.plt"]
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for i in range(0, rela_plt.sh_size, rela_plt.sh_entsize):
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rela = Elf64_Rela.from_buffer(memoryview(elf)[rela_plt.sh_offset + i:])
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sym = resolve_string(elf, dynstr, rela.r_symbol, count=True)
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if sym in [b"__aarch64_ldadd4_acq_rel", b"__aarch64_swp4_acq_rel"]:
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print(f"patching {sym} plt reloc to point into injected code")
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rela.r_type = 1027 # R_AARCH64_RELATIVE
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rela.r_addend = inject_addr
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if sym == b"__aarch64_swp4_acq_rel":
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rela.r_addend += 6*4
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with open(sys.argv[2], "wb") as outfile:
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outfile.write(memoryview(elf)[:elf_length])
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