python - 从原始 ext4 图像读取文件信息和权限

Question

我正在尝试解压缩 android 11 图像/从原始 .img 获取信息以获取 selinux 信息、符号链接(symbolic link)等。
我正在使用这个很棒的工具:https://github.com/cubinator/ext4/blob/master/ext4.py35.py
我的代码如下所示:

#!/usr/bin/env python3

import argparse
import sys
import os
import ext4

parser = argparse.ArgumentParser(description='Read <modes, symlinks, contexts and capabilities> from an ext4 image')
parser.add_argument('ext4_image', help='Path to ext4 image to process')
args = parser.parse_args()
exists = os.path.isfile(args.ext4_image)
if not exists:
    print("Error: input file " f"[{args.ext4_image}]" " was not found")
    sys.exit(1)

file = open(args.ext4_image, "rb")
volume = ext4.Volume(file)

def scan_dir (root_inode, root_path = ""):
    for entry_name, entry_inode_idx, entry_type in root_inode.open_dir():
        if entry_name == "." or entry_name == "..":
            continue
        entry_inode = root_inode.volume.get_inode(entry_inode_idx)
        entry_inode_path = root_path + "/" + entry_name
        if entry_inode.is_dir:
            scan_dir(entry_inode, entry_inode_path)
        if entry_inode_path[-1] == '/':
            continue
        xattrs_perms = list(entry_inode.xattrs())
        found_cap = False
        found_con = False
        if "security.capability" in f"{xattrs_perms}": found_cap = True
        if "security.selinux" in f"{xattrs_perms}": found_con = True
        contexts = ""
        capability = ", \"capabilities\", 0x0"
        if found_cap:
            if found_con:
                capability = f"{xattrs_perms[1:2]}"
            else:
                capability = f"{xattrs_perms[0:1]}"
            capability = capability.split(" ")[1][:-3][+2:].encode('utf-8').decode('unicode-escape').encode('ISO-8859-1')
            capability = hex(int.from_bytes(capability[4:8] + capability[14:18], "little"))
            capability = ", \"capabilities\", " f"{capability}"
            capability = f"{capability}"
        if found_con:
            contexts = f"{xattrs_perms[0:1]}"
            contexts = f"{contexts.split( )[1].split('x00')[0][:-1][+2:]}"
            contexts = f"{contexts}"
        filefolder = ''.join(entry_inode_path.split('/', 1))
        print("set_metadata(\""f"{filefolder}" "\", \"uid\", " f"{str(entry_inode.inode.i_uid)}" ", \"gid\", " f"{str(entry_inode.inode.i_gid)}"  ", \"mode\", " f"{entry_inode.inode.i_mode & 0x1FF:0>4o}" f"{capability}" ", \"selabel\", \"" f"{contexts}" "\");")

scan_dir(volume.root)
file.close()

那我只需要做 ./read.py vendor.img它有效。
直到最近我从 android 11 尝试了这个奇怪的 vendor.img 并得到了这个奇怪的问题。

Traceback (most recent call last):
  File "./tools/metadata.py", line 53, in <module>
    scan_dir(volume.root)
  File "./tools/metadata.py", line 26, in scan_dir
    scan_dir(entry_inode, entry_inode_path)
  File "./tools/metadata.py", line 26, in scan_dir
    scan_dir(entry_inode, entry_inode_path)
  File "./tools/metadata.py", line 29, in scan_dir
    xattrs_perms = list(entry_inode.xattrs())
  File "/home/semaphore/unpacker/tools/ext4.py", line 976, in xattrs
    for xattr_name, xattr_value in self._parse_xattrs(inline_data[offset:], 0, prefix_override = prefix_override):
  File "/home/semaphore/unpacker/tools/ext4.py", line 724, in _parse_xattrs
    xattr_inode = self.volume.get_inode(xattr.e_value_inum, InodeType.FILE)
NameError: name 'xattr' is not defined

我已经尝试删除 if 并仅在 else 之后保留代码: https://github.com/cubinator/ext4/blob/master/ext4.py35.py#L722
可惜没有运气。工具好像还没完成？但没有其他选择。
欢迎任何帮助:)
谢谢你。
编辑:有人建议更换 xattr与 xattr_entry所以我做了，我得到了这个错误: takes 2 positional arguments but 3 were given我尝试修复它并得到:

File "/home/semaphore/unpacker/tools/ext4.py", line 724, in _parse_xattrs
  xattr_inode = self.volume.get_inode(xattr_entry.e_value_inum)
File "/home/semaphore/unpacker/tools/ext4.py", line 595, in get_inode
  inode_table_offset = self.group_descriptors[group_idx].bg_inode_table * self.block_size
IndexError: list index out of range

而且我无法修复此错误:(
也许有一种替代方法可以从原始 ext4 镜像中获取 selinux 信息、功能、uid、gid、权限？

Answer 1

我读到您曾尝试自己解决此问题，但您从未发布过您当前使用的代码片段。
我不确定，但在我看来，您修改了 get_inode 的签名，而不是修改传递给它的参数。
例如。你试过了吗:

xattr_inode = self.volume.get_inode(xattr_entry.e_value_inum)