Mini Shell

# -*- coding: utf-8 -*-

# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2019 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
# Module contains functions for remounting /proc with hidepid=2 option
# see CAG-796 for details

from __future__ import print_function
from __future__ import absolute_import
import subprocess
from clcommon.sysctl import SysCtlConf, SYSCTL_CL_CONF_FILE
from clcommon.utils import grep


def hidepid_found():
    """
    Search for line like "proc /proc proc defaults,hidepid=2,gid=clsupergid 0 0" in /etc/fstab
    Return True if /proc is mounted with hidepid option in /etc/fstab
    """
    fstab = '/etc/fstab'
    try:
        with open(fstab, 'r') as f:
            for line in f:
                line = line.strip()
                if line and not line.startswith('#'):
                    splitted_line = line.split()
                    if splitted_line and splitted_line[0] == 'proc' and 'hidepid=' in splitted_line[3]:
                        return True
    except (IOError, IndexError) as e:
        print('Error: failed to parse', fstab, ':', str(e))
    return False


def execute(cmd, verbose):
    if verbose:
        print('executing', ' '.join(cmd))
    return subprocess.call(cmd)


def remount_proc(verbose=False):
    """
    Remount /proc with hidepid=2 option when needed
    """
    sysctl = SysCtlConf(config_file=SYSCTL_CL_CONF_FILE)
    if verbose:
        print('apply sysctl settings')
    if hidepid_found():
        # admin can override hidepid option via /etc/fstab
        if verbose:
            print('hidepid option is found in /etc/fstab - remounting /proc with options from /etc/fstab')
        return execute(['/bin/mount', '-o', 'remount', '/proc'], verbose)
    proc_can_see_other_uid = sysctl.get('fs.proc_can_see_other_uid')
    super_gid = sysctl.get('fs.proc_super_gid')
    if proc_can_see_other_uid != '0':
        if verbose:
            print('virtualized procfs feature is not enabled in sysctl conf - disable hidepid')
        return execute(['/bin/mount', '-o', 'remount,hidepid=0,gid=0', '/proc'], verbose)
    if verbose:
        print('enable hidepid for /proc')
    return execute(['/bin/mount', '-o', 'remount,hidepid=2,gid='+super_gid, '/proc'], verbose)


def get_gid_from_mounts():
    """
    Retrieve hidepid gid from /proc/mounts
    :return: gid, 0 if absent
    """
    lines_gen = grep(',hidepid=', '/proc/mounts')
    gid_prefix = ',gid='
    try:
        for line in lines_gen:
            line = line.strip()
            if gid_prefix not in line:
                continue
            # Search gid=xxxx in line
            pos = line.find(gid_prefix)
            if pos == -1:
                continue
            pos += 5
            line = line[pos:]
            pos = line.find(',')
            if pos != -1:
                line = line[:pos]
            else:
                pos = line.find(' ')
                if pos != -1:
                    line = line[:pos]
                else:
                    # Invalid or unsupported proc format
                    return -1
            return int(line)
    except (IOError, IndexError, ValueError):
        pass
    # hidepid not found in /proc/mounts
    return -1


def get_hidepid_typing_from_mounts() -> int:
    """
    Retrieve hidepid value from /proc/mounts
    :return: hidepid, 0 is absent
    """
    mounts_path = '/proc/mounts'
    hidepid_prefix = 'hidepid='
    try:
        # Parse mounts file output for proc lines and get the hidepid
        with open(mounts_path, mode='r') as file:
            for line in file:
                if (not line.strip().startswith('proc /proc') or
                        hidepid_prefix not in line):
                    continue
                pos = line.find(hidepid_prefix) + len(hidepid_prefix)
                return int(line[pos])
    except (OSError, IOError, IndexError, ValueError):
        pass
    # hidepid not found in /proc/mounts
    return 0