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130 lines
4.7 KiB
Python
130 lines
4.7 KiB
Python
#
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# Copyright (c) 2021-2025 ahriman team.
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#
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# This file is part of ahriman
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# (see https://github.com/arcan1s/ahriman).
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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from grp import getgrnam
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from pwd import getpwnam
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from ahriman.core.auth.mapping import Mapping
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from ahriman.core.configuration import Configuration
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from ahriman.core.database import SQLite
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from ahriman.core.exceptions import CalledProcessError
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from ahriman.core.utils import check_output
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from ahriman.models.auth_settings import AuthSettings
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from ahriman.models.user_access import UserAccess
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class PAM(Mapping):
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"""
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User authorization implementation by using default PAM
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Attributes:
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full_access_group(str): group name users of which have full access
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permit_root_login(bool): permit login as root
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"""
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def __init__(self, configuration: Configuration, database: SQLite,
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provider: AuthSettings = AuthSettings.PAM) -> None:
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"""
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Args:
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configuration(Configuration): configuration instance
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database(SQLite): database instance
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provider(AuthSettings, optional): authorization type definition (Default value = AuthSettings.PAM)
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"""
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Mapping.__init__(self, configuration, database, provider)
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self.full_access_group = configuration.get("auth", "full_access_group")
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self.permit_root_login = configuration.getboolean("auth", "permit_root_login", fallback=False)
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@staticmethod
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def group_members(group_name: str) -> list[str]:
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"""
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extract current group members
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Args:
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group_name(str): group name
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Returns:
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list[str]: list of users which belong to the specified group. In case if group wasn't found, the empty list
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will be returned
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"""
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try:
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group = getgrnam(group_name)
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except KeyError:
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return []
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return group.gr_mem
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async def check_credentials(self, username: str, password: str | None) -> bool:
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"""
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validate user password
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Args:
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username(str): username
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password(str | None): entered password
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Returns:
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bool: ``True`` in case if password matches, ``False`` otherwise
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"""
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if password is None:
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return False # invalid data supplied
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if not self.permit_root_login and username == "root":
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return False # login as root is not allowed
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# the reason why do we call su here is that python-pam actually read shadow file
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# and hence requires root privileges
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try:
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check_output("su", "--command", "true", "-", username, input_data=password)
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return True
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except CalledProcessError:
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return await Mapping.check_credentials(self, username, password)
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async def known_username(self, username: str) -> bool:
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"""
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check if user is known
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Args:
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username(str): username
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Returns:
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bool: ``True`` in case if user is known and can be authorized and ``False`` otherwise
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"""
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try:
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_ = getpwnam(username)
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return True
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except KeyError:
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return await Mapping.known_username(self, username)
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async def verify_access(self, username: str, required: UserAccess, context: str | None) -> bool:
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"""
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validate if user has access to requested resource
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Args:
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username(str): username
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required(UserAccess): required access level
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context(str | None): URI request path
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Returns:
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bool: ``True`` in case if user is allowed to do this request and ``False`` otherwise
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"""
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# this method is basically inverted, first we check overrides in database and then fallback to the PAM logic
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if (user := await self.get_user(username)) is not None:
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return user.verify_access(required)
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# if username is in admin group, then we treat it as full access
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if username in self.group_members(self.full_access_group):
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return UserAccess.Full.permits(required)
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# fallback to read-only accounts
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return UserAccess.Read.permits(required)
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