Python删除进程用户权限（获取用户权限、用户权限，设置用户权限、用户权限）

本文深入探讨了Python中如何使用os、pwd和grp模块实现权限下降，通过drop_privileges函数，从root用户切换到指定的普通用户，确保程序运行在更安全的权限级别下。

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import os
import argparse
import logging
import sys
import pwd
import grp
from configparser import ConfigParser, NoSectionError, NoOptionError


def drop_privileges(uid_name=None, gid_name=None):
    if uid_name is None:
        uid_name = 'nobody'

    try:
        wanted_user = pwd.getpwnam(uid_name)
    except KeyError:
        logger.exception(
            'Cannot drop privileges: user "{}" does not exist.'.
            format(uid_name))
        sys.exit(1)

    if gid_name is None:
        gid_name = grp.getgrgid(wanted_user.pw_gid).gr_name

    try:
        wanted_group = grp.getgrnam(gid_name)
    except KeyError:
        logger.exception(
            'Cannot drop privileges: group "{}" does not exist.'.
            format(gid_name))
        sys.exit(1)

    logger.debug('Attempting to drop privileges to "{}:{}"'.
                format(wanted_user.pw_name, wanted_group.gr_name))
    os.setgid(wanted_group.gr_gid)
    os.setuid(wanted_user.pw_uid)
    new_user = pwd.getpwuid(os.getuid())
    new_group = grp.getgrgid(os.getgid())
    logger.info('Privileges dropped, running as "{}:{}"'.
                format(new_user.pw_name, new_group.gr_name))




if __name__ == "__main__":
    config = ConfigParser(os.environ)

    if os.getuid() == 0:
        if not args.force:
            logger.critical("Can't start conpot with root. Please ref user docs for more info.")
            sys.exit(3)
        else:
            logger.warning('Running conpot with root. Running conpot with root isn\'t recommended. ')

    if os.getuid() == 0:
        try:
            # retrieve user to run as
            conpot_user = config.get('daemon', 'user')
        except (NoSectionError, NoOptionError):
            conpot_user = None

        try:
            # retrieve group to run as
            conpot_group = config.get('daemon', 'group')
        except (NoSectionError, NoOptionError):
            conpot_group = None
        # FIXME: drop privs require sudo
        drop_privileges(conpot_user, conpot_group)

解释：

1、pwd模块

pwd模块提供了一个unix密码数据库即/etc/passwd的操作接口，这个数据库包含本地机器用户帐户信息

常用操作如下：

pwd.getpwuid(uid)：返回对应uid的示例信息

示例：

>>> pwd.getpwuid(0)       
pwd.struct_passwd(pw_name='root', pw_passwd='x', pw_uid=0, pw_gid=0, pw_gecos='root', pw_dir='/root', pw_shell='/bin/bash')

pwd.getpwnam(name)：返回对应name的用户信息

示例：

>>> pwd.getpwnam('root')
pwd.struct_passwd(pw_name='root', pw_passwd='x', pw_uid=0, pw_gid=0, pw_gecos='root', pw_dir='/root', pw_shell='/bin/bash')

pwd.getpwall()：返回所有的用户信息

示例：

import pwd

def get_user()
    all_user = {}
    for user in pwd.getpwall()
        all_user[user[0]] = all_user[user[2]] = user
    return all_user

def userinfo(uid):
    return get_user()[uid]

执行结果：

print userinfo(0)
pwd.struct_passwd(pw_name='root', pw_passwd='x', pw_uid=0, pw_gid=0, pw_gecos='root', pw_dir='/root', pw_shell='/bin/bash')
print userinfo('root')
pwd.struct_passwd(pw_name='root', pw_passwd='x', pw_uid=0, pw_gid=0, pw_gecos='root', pw_dir='/root', pw_shell='/bin/bash')

2、grp模块

grp模块提供了一个操作unix用户组即/etc/group数据库的接口

常用操作如下：

grp.getgrgid(gid)：返回对应gid的组信息

示例：

>>> print grp.getgrgid(0)
grp.struct_group(gr_name='root', gr_passwd='x', gr_gid=0, gr_mem=[])

grp.getgrnam(name)：返回对应name的组信息

示例：

>>> print grp.getgrnam('root')
grp.struct_group(gr_name='root', gr_passwd='x', gr_gid=0, gr_mem=[])

grp.getgrall()：返回所有的组信息