tildetown-admin/ttadmin/users/models.py

222 lines
8.3 KiB
Python

import logging
import os
from subprocess import run, CalledProcessError
from tempfile import TemporaryFile
from django.db.models import Model
from django.db.models.signals import pre_save, post_save
from django.dispatch import receiver
from django.contrib.auth.models import User
from django.db.models import TextField, BooleanField, CharField, ForeignKey
from django.template.loader import get_template
from common.mailing import send_email
from help.models import Ticket
logger = logging.getLogger()
SSH_TYPE_CHOICES = (
('ssh-rsa', 'ssh-rsa',),
('ssh-dss', 'ssh-dss',),
('ecdsa-sha2-nistp256', 'ecdsa-sha2-nistp256'),
)
DEFAULT_INDEX_PATH = '/etc/skel/public_html/index.html'
if os.path.exists(DEFAULT_INDEX_PATH):
DEFAULT_INDEX_PAGE = open(DEFAULT_INDEX_PATH).read().rstrip()
else:
logger.warning('No default html page found in skel. using empty string.')
DEFAULT_INDEX_PAGE = ''
KEYFILE_HEADER = """########## GREETINGS! ##########
# Hi! This file is automatically managed by tilde.town. You
# seriously shouldn't change it. If you want to add more public keys that's
# totally fine: you can put them in ~/.ssh/authorized_keys"""
class Townie(User):
"""Both an almost normal Django User as well as an abstraction over a
system user."""
class Meta:
verbose_name = 'Townie'
verbose_name_plural = 'Townies'
shell = CharField(max_length=50, default="/bin/bash")
reviewed = BooleanField(default=False)
reasons = TextField(blank=True, null=False, default='')
displayname = CharField(max_length=100, blank=False, null=False)
@property
def home(self):
return os.path.join('/home', self.username)
def send_welcome_email(self, admin_name='vilmibm'):
welcome_tmpl = get_template('users/welcome_email.txt')
context = {
'username': self.username,
'admin_name': admin_name,
}
text = welcome_tmpl.render(context)
from_address = '{}@tilde.town'.format(admin_name)
success = send_email(self.email, text, subject='tilde.town!',
frum=from_address)
if not success:
Ticket.objects.create(name='system',
email='root@tilde.town',
issue_type='other',
issue_text='was not able to send welcome email to {} ({})'.format(
self.username,
self.email))
# managing concrete system state
def has_modified_page(self):
"""Returns whether or not the user has modified index.html. If they
don't have one, returns False."""
index_path = os.path.join(self.home, 'public_html/index.html')
if not os.path.exists(index_path):
return False
index_page = open(index_path).read().rstrip()
return index_page != DEFAULT_INDEX_PAGE
def create_on_disk(self):
"""A VERY NOT IDEMPOTENT create function. Originally, I had ambitions
to have this be idempotent and able to incrementally update a user as
needed, but decided that was overkill for now."""
assert(self.reviewed)
dot_ssh_path = '/home/{}/.ssh'.format(self.username)
error = _guarded_run(['sudo',
'adduser',
'--quiet',
'--shell={}'.format(self.shell),
'--gecos="{}"'.format(self.displayname),
'--disabled-password',
self.username])
if error:
logging.error(error)
return
error = _guarded_run(['sudo',
'usermod',
'-a',
'-Gtown',
self.username])
if error:
logging.error(error)
return
# Create .ssh
error = _guarded_run(['sudo',
'--user={}'.format(self.username),
'mkdir',
dot_ssh_path])
if error:
logging.error(error)
return
def write_authorized_keys(self):
# Write out authorized_keys file
# Why is this a call out to a python script? There's no secure way with
# sudoers to allow this code to write to a file; if this code was to be
# compromised, the ability to write arbitrary files with sudo is a TKO.
# By putting the ssh key file creation into its own script, we can just
# give sudo access for that one command to this code.
#
# We could put the other stuff from here into that script and then only
# grant sudo for the script, but then we're moving code out of this
# virtual-env contained, maintainable thing into a script. it's my
# preference to have the script be as minimal as possible.
with TemporaryFile(dir="/tmp") as fp:
fp.write(self.generate_authorized_keys().encode('utf-8'))
fp.seek(0)
error = _guarded_run(['sudo',
'--user={}'.format(self.username),
'/opt/bin/create_keyfile.py',
self.username],
stdin=fp)
if error:
logging.error(error)
def generate_authorized_keys(self):
"""returns a string suitable for writing out to an authorized_keys
file"""
content = KEYFILE_HEADER
for pubkey in self.pubkey_set.all():
if pubkey.key.startswith('ssh-'):
content += '\n{}'.format(pubkey.key)
else:
content += '\n{} {}'.format(pubkey.key_type, pubkey.key)
return content
class Pubkey(Model):
key_type = CharField(max_length=50,
blank=False,
null=False,
choices=SSH_TYPE_CHOICES,
)
key = TextField(blank=False, null=False)
townie = ForeignKey(Townie)
@receiver(post_save, sender=Pubkey)
def on_pubkey_post_save(sender, instance, **kwargs):
instance.townie.write_authorized_keys()
@receiver(pre_save, sender=Townie)
def on_townie_pre_save(sender, instance, **kwargs):
existing = Townie.objects.filter(username=instance.username)
if not existing:
# we're making a new Townie; this means someone just signed up. We
# don't care at all about their state on disk.
return
existing = existing[0]
if not existing.reviewed and instance.reviewed == True:
instance.create_on_disk()
instance.send_welcome_email()
instance.write_authorized_keys()
def _guarded_run(cmd_args, **run_args):
"""Given a list of args representing a command invocation as well as var
args to pass onto subprocess.run, run the command and check for an error.
if there is one, files a helpdesk ticket and returns it. Returns None on
success."""
try:
run(cmd_args,
check=True,
**run_args)
except CalledProcessError as e:
Ticket.objects.create(name='system',
email='root@tilde.town',
issue_type='other',
issue_text='error while running {}: {}'.format(
cmd_args, e))
return e
# things to consider:
# * what happens when a user wants their name changed?
# * it looks like usermod -l and a mv of the home dir can change a user's username.
# * would hook this into the pre_save signal to note a username change
# * what happens when a user is marked as not reviewed?
# * does this signal user deletion? Or does literal Townie deletion signal
# "needs to be removed from disk"? I think it makes the most sense for the
# latter to imply full user deletion.
# * I honestly can't even think of a reason to revert a user to "not reviewed"
# and perhaps it's best to just not make that possible. for now, though, I
# think I can ignore it.
# * what happens when a user needs to be banned?
# * the Townie should be deleted via post_delete signal
# * what are things about a user that might change in django and require changes on disk?
# * username
# * displayname (only if i start using this?)
# * ssh key