path: root/bin/python/isc/policy.py.in

# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# SPDX-License-Identifier: MPL-2.0
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0.  If a copy of the MPL was not distributed with this
# file, you can obtain one at https://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.

import re
import ply.lex as lex
import ply.yacc as yacc
from string import *
from copy import copy


############################################################################
# PolicyLex: a lexer for the policy file syntax.
############################################################################
class PolicyLex:
    reserved = (
        "POLICY",
        "ALGORITHM_POLICY",
        "ZONE",
        "ALGORITHM",
        "DIRECTORY",
        "KEYTTL",
        "KEY_SIZE",
        "ROLL_PERIOD",
        "PRE_PUBLISH",
        "POST_PUBLISH",
        "COVERAGE",
        "STANDBY",
        "NONE",
    )

    tokens = reserved + (
        "DATESUFFIX",
        "KEYTYPE",
        "ALGNAME",
        "STR",
        "QSTRING",
        "NUMBER",
        "LBRACE",
        "RBRACE",
        "SEMI",
    )
    reserved_map = {}

    t_ignore = " \t"
    t_ignore_olcomment = r"(//|\#).*"

    t_LBRACE = r"\{"
    t_RBRACE = r"\}"
    t_SEMI = r";"

    def t_newline(self, t):
        r"\n+"
        t.lexer.lineno += t.value.count("\n")

    def t_comment(self, t):
        r"/\*(.|\n)*?\*/"
        t.lexer.lineno += t.value.count("\n")

    def t_DATESUFFIX(self, t):
        r"(?<=[0-9 \t])(y(?:ears|ear|ea|e)?|mo(?:nths|nth|nt|n)?|w(?:eeks|eek|ee|e)?|d(?:ays|ay|a)?|h(?:ours|our|ou|o)?|mi(?:nutes|nute|nut|nu|n)?|s(?:econds|econd|econ|eco|ec|e)?)\b"
        t.value = (
            re.match(r"(y|mo|w|d|h|mi|s)([a-z]*)", t.value, re.IGNORECASE)
            .group(1)
            .lower()
        )
        return t

    def t_KEYTYPE(self, t):
        r"\b(KSK|ZSK)\b"
        t.value = t.value.upper()
        return t

    def t_ALGNAME(self, t):
        r"\b(DH|ECC|RSASHA1|NSEC3RSASHA1|RSASHA256|RSASHA512|ECDSAP256SHA256|ECDSAP384SHA384|ED25519|ED448)\b"
        t.value = t.value.upper()
        return t

    def t_STR(self, t):
        r"[A-Za-z._-][\w._-]*"
        t.type = self.reserved_map.get(t.value, "STR")
        return t

    def t_QSTRING(self, t):
        r'"([^"\n]|(\\"))*"'
        t.type = self.reserved_map.get(t.value, "QSTRING")
        t.value = t.value[1:-1]
        return t

    def t_NUMBER(self, t):
        r"\d+"
        t.value = int(t.value)
        return t

    def t_error(self, t):
        print("Illegal character '%s'" % t.value[0])
        t.lexer.skip(1)

    def __init__(self, **kwargs):
        if "maketrans" in dir(str):
            trans = str.maketrans("_", "-")
        else:
            trans = maketrans("_", "-")
        for r in self.reserved:
            self.reserved_map[r.lower().translate(trans)] = r
        self.lexer = lex.lex(object=self, reflags=re.VERBOSE | re.IGNORECASE, **kwargs)

    def test(self, text):
        self.lexer.input(text)
        while True:
            t = self.lexer.token()
            if not t:
                break
            print(t)


############################################################################
# Policy: this object holds a set of DNSSEC policy settings.
############################################################################
class Policy:
    is_zone = False
    is_alg = False
    is_constructed = False
    ksk_rollperiod = None
    zsk_rollperiod = None
    ksk_prepublish = None
    zsk_prepublish = None
    ksk_postpublish = None
    zsk_postpublish = None
    ksk_keysize = None
    zsk_keysize = None
    ksk_standby = None
    zsk_standby = None
    keyttl = None
    coverage = None
    directory = None
    valid_key_sz_per_algo = {
        "RSASHA1": [1024, 4096],
        "NSEC3RSASHA1": [512, 4096],
        "RSASHA256": [1024, 4096],
        "RSASHA512": [1024, 4096],
        "ECDSAP256SHA256": None,
        "ECDSAP384SHA384": None,
        "ED25519": None,
        "ED448": None,
    }

    def __init__(self, name=None, algorithm=None, parent=None):
        self.name = name
        self.algorithm = algorithm
        self.parent = parent
        pass

    def __repr__(self):
        return (
            "%spolicy %s:\n"
            "\tinherits %s\n"
            "\tdirectory %s\n"
            "\talgorithm %s\n"
            "\tcoverage %s\n"
            "\tksk_keysize %s\n"
            "\tzsk_keysize %s\n"
            "\tksk_rollperiod %s\n"
            "\tzsk_rollperiod %s\n"
            "\tksk_prepublish %s\n"
            "\tksk_postpublish %s\n"
            "\tzsk_prepublish %s\n"
            "\tzsk_postpublish %s\n"
            "\tksk_standby %s\n"
            "\tzsk_standby %s\n"
            "\tkeyttl %s\n"
            % (
                (
                    self.is_constructed
                    and "constructed "
                    or self.is_zone
                    and "zone "
                    or self.is_alg
                    and "algorithm "
                    or ""
                ),
                self.name or "UNKNOWN",
                self.parent and self.parent.name or "None",
                self.directory and ('"' + str(self.directory) + '"') or "None",
                self.algorithm or "None",
                self.coverage and str(self.coverage) or "None",
                self.ksk_keysize and str(self.ksk_keysize) or "None",
                self.zsk_keysize and str(self.zsk_keysize) or "None",
                self.ksk_rollperiod and str(self.ksk_rollperiod) or "None",
                self.zsk_rollperiod and str(self.zsk_rollperiod) or "None",
                self.ksk_prepublish and str(self.ksk_prepublish) or "None",
                self.ksk_postpublish and str(self.ksk_postpublish) or "None",
                self.zsk_prepublish and str(self.zsk_prepublish) or "None",
                self.zsk_postpublish and str(self.zsk_postpublish) or "None",
                self.ksk_standby and str(self.ksk_standby) or "None",
                self.zsk_standby and str(self.zsk_standby) or "None",
                self.keyttl and str(self.keyttl) or "None",
            )
        )

    def __verify_size(self, key_size, size_range):
        return size_range[0] <= key_size <= size_range[1]

    def get_name(self):
        return self.name

    def constructed(self):
        return self.is_constructed

    def validate(self):
        """Check if the values in the policy make sense
        :return: True/False if the policy passes validation
        """
        if (
            self.ksk_rollperiod
            and self.ksk_prepublish is not None
            and self.ksk_prepublish > self.ksk_rollperiod
        ):
            print(self.ksk_rollperiod)
            return (
                False,
                (
                    "KSK pre-publish period (%d) exceeds rollover period %d"
                    % (self.ksk_prepublish, self.ksk_rollperiod)
                ),
            )

        if (
            self.ksk_rollperiod
            and self.ksk_postpublish is not None
            and self.ksk_postpublish > self.ksk_rollperiod
        ):
            return (
                False,
                (
                    "KSK post-publish period (%d) exceeds rollover period %d"
                    % (self.ksk_postpublish, self.ksk_rollperiod)
                ),
            )

        if (
            self.zsk_rollperiod
            and self.zsk_prepublish is not None
            and self.zsk_prepublish >= self.zsk_rollperiod
        ):
            return (
                False,
                (
                    "ZSK pre-publish period (%d) exceeds rollover period %d"
                    % (self.zsk_prepublish, self.zsk_rollperiod)
                ),
            )

        if (
            self.zsk_rollperiod
            and self.zsk_postpublish is not None
            and self.zsk_postpublish >= self.zsk_rollperiod
        ):
            return (
                False,
                (
                    "ZSK post-publish period (%d) exceeds rollover period %d"
                    % (self.zsk_postpublish, self.zsk_rollperiod)
                ),
            )

        if (
            self.ksk_rollperiod
            and self.ksk_prepublish
            and self.ksk_postpublish
            and self.ksk_prepublish + self.ksk_postpublish >= self.ksk_rollperiod
        ):
            return (
                False,
                (
                    (
                        "KSK pre/post-publish periods (%d/%d) "
                        + "combined exceed rollover period %d"
                    )
                    % (self.ksk_prepublish, self.ksk_postpublish, self.ksk_rollperiod)
                ),
            )

        if (
            self.zsk_rollperiod
            and self.zsk_prepublish
            and self.zsk_postpublish
            and self.zsk_prepublish + self.zsk_postpublish >= self.zsk_rollperiod
        ):
            return (
                False,
                (
                    (
                        "ZSK pre/post-publish periods (%d/%d) "
                        + "combined exceed rollover period %d"
                    )
                    % (self.zsk_prepublish, self.zsk_postpublish, self.zsk_rollperiod)
                ),
            )

        if self.algorithm is not None:
            # Validate the key size
            key_sz_range = self.valid_key_sz_per_algo.get(self.algorithm)
            if key_sz_range is not None:
                # Verify KSK
                if not self.__verify_size(self.ksk_keysize, key_sz_range):
                    return False, "KSK key size %d outside valid range %s" % (
                        self.ksk_keysize,
                        key_sz_range,
                    )

                # Verify ZSK
                if not self.__verify_size(self.zsk_keysize, key_sz_range):
                    return False, "ZSK key size %d outside valid range %s" % (
                        self.zsk_keysize,
                        key_sz_range,
                    )

            if self.algorithm in [
                "ECDSAP256SHA256",
                "ECDSAP384SHA384",
                "ED25519",
                "ED448",
            ]:
                self.ksk_keysize = None
                self.zsk_keysize = None

        return True, ""


############################################################################
# dnssec_policy:
# This class reads a dnssec.policy file and creates a dictionary of
# DNSSEC policy rules from which a policy for a specific zone can
# be generated.
############################################################################
class PolicyException(Exception):
    pass


class dnssec_policy:
    alg_policy = {}
    named_policy = {}
    zone_policy = {}
    current = None
    filename = None
    initial = True

    def __init__(self, filename=None, **kwargs):
        self.plex = PolicyLex()
        self.tokens = self.plex.tokens
        if "debug" not in kwargs:
            kwargs["debug"] = False
        if "write_tables" not in kwargs:
            kwargs["write_tables"] = False
        self.parser = yacc.yacc(module=self, **kwargs)

        # set defaults
        self.setup(
            """policy global { algorithm rsasha256;
                                      key-size ksk 2048;
                                      key-size zsk 2048;
                                      roll-period ksk 0;
                                      roll-period zsk 1y;
                                      pre-publish ksk 1mo;
                                      pre-publish zsk 1mo;
                                      post-publish ksk 1mo;
                                      post-publish zsk 1mo;
                                      standby ksk 0;
                                      standby zsk 0;
                                      keyttl 1h;
                                      coverage 6mo; };
                      policy default { policy global; };"""
        )

        p = Policy()
        p.algorithm = None
        p.is_alg = True
        p.ksk_keysize = 2048
        p.zsk_keysize = 2048

        # set default algorithm policies

        # these can use default settings
        self.alg_policy["RSASHA1"] = copy(p)
        self.alg_policy["RSASHA1"].algorithm = "RSASHA1"
        self.alg_policy["RSASHA1"].name = "RSASHA1"

        self.alg_policy["NSEC3RSASHA1"] = copy(p)
        self.alg_policy["NSEC3RSASHA1"].algorithm = "NSEC3RSASHA1"
        self.alg_policy["NSEC3RSASHA1"].name = "NSEC3RSASHA1"

        self.alg_policy["RSASHA256"] = copy(p)
        self.alg_policy["RSASHA256"].algorithm = "RSASHA256"
        self.alg_policy["RSASHA256"].name = "RSASHA256"

        self.alg_policy["RSASHA512"] = copy(p)
        self.alg_policy["RSASHA512"].algorithm = "RSASHA512"
        self.alg_policy["RSASHA512"].name = "RSASHA512"

        self.alg_policy["ECDSAP256SHA256"] = copy(p)
        self.alg_policy["ECDSAP256SHA256"].algorithm = "ECDSAP256SHA256"
        self.alg_policy["ECDSAP256SHA256"].name = "ECDSAP256SHA256"
        self.alg_policy["ECDSAP256SHA256"].ksk_keysize = None
        self.alg_policy["ECDSAP256SHA256"].zsk_keysize = None

        self.alg_policy["ECDSAP384SHA384"] = copy(p)
        self.alg_policy["ECDSAP384SHA384"].algorithm = "ECDSAP384SHA384"
        self.alg_policy["ECDSAP384SHA384"].name = "ECDSAP384SHA384"
        self.alg_policy["ECDSAP384SHA384"].ksk_keysize = None
        self.alg_policy["ECDSAP384SHA384"].zsk_keysize = None

        self.alg_policy["ED25519"] = copy(p)
        self.alg_policy["ED25519"].algorithm = "ED25519"
        self.alg_policy["ED25519"].name = "ED25519"
        self.alg_policy["ED25519"].ksk_keysize = None
        self.alg_policy["ED25519"].zsk_keysize = None

        self.alg_policy["ED448"] = copy(p)
        self.alg_policy["ED448"].algorithm = "ED448"
        self.alg_policy["ED448"].name = "ED448"
        self.alg_policy["ED448"].ksk_keysize = None
        self.alg_policy["ED448"].zsk_keysize = None

        if filename:
            self.load(filename)

    def load(self, filename):
        self.filename = filename
        self.initial = True
        with open(filename) as f:
            text = f.read()
            self.plex.lexer.lineno = 0
            self.parser.parse(text)

        self.filename = None

    def setup(self, text):
        self.initial = True
        self.plex.lexer.lineno = 0
        self.parser.parse(text)

    def policy(self, zone, **kwargs):
        z = zone.lower()
        p = None

        if z in self.zone_policy:
            p = self.zone_policy[z]

        if p is None:
            p = copy(self.named_policy["default"])
            p.name = zone
            p.is_constructed = True

        if p.algorithm is None:
            parent = p.parent or self.named_policy["default"]
            while parent and not parent.algorithm:
                parent = parent.parent
            p.algorithm = parent and parent.algorithm or None

        if p.algorithm in self.alg_policy:
            ap = self.alg_policy[p.algorithm]
        else:
            raise PolicyException("algorithm not found")

        if p.directory is None:
            parent = p.parent or self.named_policy["default"]
            while parent is not None and not parent.directory:
                parent = parent.parent
            p.directory = parent and parent.directory

        if p.coverage is None:
            parent = p.parent or self.named_policy["default"]
            while parent and not parent.coverage:
                parent = parent.parent
            p.coverage = parent and parent.coverage or ap.coverage

        if p.ksk_keysize is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.ksk_keysize:
                parent = parent.parent
            p.ksk_keysize = parent and parent.ksk_keysize or ap.ksk_keysize

        if p.zsk_keysize is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.zsk_keysize:
                parent = parent.parent
            p.zsk_keysize = parent and parent.zsk_keysize or ap.zsk_keysize

        if p.ksk_rollperiod is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.ksk_rollperiod:
                parent = parent.parent
            p.ksk_rollperiod = parent and parent.ksk_rollperiod or ap.ksk_rollperiod

        if p.zsk_rollperiod is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.zsk_rollperiod:
                parent = parent.parent
            p.zsk_rollperiod = parent and parent.zsk_rollperiod or ap.zsk_rollperiod

        if p.ksk_prepublish is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.ksk_prepublish:
                parent = parent.parent
            p.ksk_prepublish = parent and parent.ksk_prepublish or ap.ksk_prepublish

        if p.zsk_prepublish is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.zsk_prepublish:
                parent = parent.parent
            p.zsk_prepublish = parent and parent.zsk_prepublish or ap.zsk_prepublish

        if p.ksk_postpublish is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.ksk_postpublish:
                parent = parent.parent
            p.ksk_postpublish = parent and parent.ksk_postpublish or ap.ksk_postpublish

        if p.zsk_postpublish is None:
            parent = p.parent or self.named_policy["default"]
            while parent.parent and not parent.zsk_postpublish:
                parent = parent.parent
            p.zsk_postpublish = parent and parent.zsk_postpublish or ap.zsk_postpublish

        if p.keyttl is None:
            parent = p.parent or self.named_policy["default"]
            while parent is not None and not parent.keyttl:
                parent = parent.parent
            p.keyttl = parent and parent.keyttl

        if "novalidate" not in kwargs or not kwargs["novalidate"]:
            (valid, msg) = p.validate()
            if not valid:
                raise PolicyException(msg)
                return None

        return p

    def p_policylist(self, p):
        """policylist : init policy
        | policylist policy"""
        pass

    def p_init(self, p):
        "init :"
        self.initial = False

    def p_policy(self, p):
        """policy : alg_policy
        | zone_policy
        | named_policy"""
        pass

    def p_name(self, p):
        """name : STR
        | KEYTYPE
        | DATESUFFIX"""
        p[0] = p[1]
        pass

    def p_domain(self, p):
        """domain : STR
        | QSTRING
        | KEYTYPE
        | DATESUFFIX"""
        p[0] = p[1].strip()
        if not re.match(r"^[\w.-][\w.-]*$", p[0]):
            raise PolicyException("invalid domain")
        pass

    def p_new_policy(self, p):
        "new_policy :"
        self.current = Policy()

    def p_alg_policy(self, p):
        "alg_policy : ALGORITHM_POLICY ALGNAME new_policy alg_option_group SEMI"
        self.current.name = p[2]
        self.current.is_alg = True
        self.alg_policy[p[2]] = self.current
        pass

    def p_zone_policy(self, p):
        "zone_policy : ZONE domain new_policy policy_option_group SEMI"
        self.current.name = p[2].rstrip(".")
        self.current.is_zone = True
        self.zone_policy[p[2].rstrip(".").lower()] = self.current
        pass

    def p_named_policy(self, p):
        "named_policy : POLICY name new_policy policy_option_group SEMI"
        self.current.name = p[2]
        self.named_policy[p[2].lower()] = self.current
        pass

    def p_duration_1(self, p):
        "duration : NUMBER"
        p[0] = p[1]
        pass

    def p_duration_2(self, p):
        "duration : NONE"
        p[0] = None
        pass

    def p_duration_3(self, p):
        "duration : NUMBER DATESUFFIX"
        if p[2] == "y":
            p[0] = p[1] * 31536000  # year
        elif p[2] == "mo":
            p[0] = p[1] * 2592000  # month
        elif p[2] == "w":
            p[0] = p[1] * 604800  # week
        elif p[2] == "d":
            p[0] = p[1] * 86400  # day
        elif p[2] == "h":
            p[0] = p[1] * 3600  # hour
        elif p[2] == "mi":
            p[0] = p[1] * 60  # minute
        elif p[2] == "s":
            p[0] = p[1]  # second
        else:
            raise PolicyException("invalid duration")

    def p_policy_option_group(self, p):
        "policy_option_group : LBRACE policy_option_list RBRACE"
        pass

    def p_policy_option_list(self, p):
        """policy_option_list : policy_option SEMI
        | policy_option_list policy_option SEMI"""
        pass

    def p_policy_option(self, p):
        """policy_option : parent_option
        | directory_option
        | coverage_option
        | rollperiod_option
        | prepublish_option
        | postpublish_option
        | keysize_option
        | algorithm_option
        | keyttl_option
        | standby_option"""
        pass

    def p_alg_option_group(self, p):
        "alg_option_group : LBRACE alg_option_list RBRACE"
        pass

    def p_alg_option_list(self, p):
        """alg_option_list : alg_option SEMI
        | alg_option_list alg_option SEMI"""
        pass

    def p_alg_option(self, p):
        """alg_option : coverage_option
        | rollperiod_option
        | prepublish_option
        | postpublish_option
        | keyttl_option
        | keysize_option
        | standby_option"""
        pass

    def p_parent_option(self, p):
        "parent_option : POLICY name"
        self.current.parent = self.named_policy[p[2].lower()]

    def p_directory_option(self, p):
        "directory_option : DIRECTORY QSTRING"
        self.current.directory = p[2]

    def p_coverage_option(self, p):
        "coverage_option : COVERAGE duration"
        self.current.coverage = p[2]

    def p_rollperiod_option(self, p):
        "rollperiod_option : ROLL_PERIOD KEYTYPE duration"
        if p[2] == "KSK":
            self.current.ksk_rollperiod = p[3]
        else:
            self.current.zsk_rollperiod = p[3]

    def p_prepublish_option(self, p):
        "prepublish_option : PRE_PUBLISH KEYTYPE duration"
        if p[2] == "KSK":
            self.current.ksk_prepublish = p[3]
        else:
            self.current.zsk_prepublish = p[3]

    def p_postpublish_option(self, p):
        "postpublish_option : POST_PUBLISH KEYTYPE duration"
        if p[2] == "KSK":
            self.current.ksk_postpublish = p[3]
        else:
            self.current.zsk_postpublish = p[3]

    def p_keysize_option(self, p):
        "keysize_option : KEY_SIZE KEYTYPE NUMBER"
        if p[2] == "KSK":
            self.current.ksk_keysize = p[3]
        else:
            self.current.zsk_keysize = p[3]

    def p_standby_option(self, p):
        "standby_option : STANDBY KEYTYPE NUMBER"
        if p[2] == "KSK":
            self.current.ksk_standby = p[3]
        else:
            self.current.zsk_standby = p[3]

    def p_keyttl_option(self, p):
        "keyttl_option : KEYTTL duration"
        self.current.keyttl = p[2]

    def p_algorithm_option(self, p):
        "algorithm_option : ALGORITHM ALGNAME"
        self.current.algorithm = p[2]

    def p_error(self, p):
        if p:
            print(
                "%s%s%d:syntax error near '%s'"
                % (self.filename or "", ":" if self.filename else "", p.lineno, p.value)
            )
        else:
            if not self.initial:
                raise PolicyException(
                    "%s%s%d:unexpected end of input"
                    % (
                        self.filename or "",
                        ":" if self.filename else "",
                        p and p.lineno or 0,
                    )
                )


if __name__ == "__main__":
    import sys

    if sys.argv[1] == "lex":
        file = open(sys.argv[2])
        text = file.read()
        file.close()
        plex = PolicyLex(debug=1)
        plex.test(text)
    elif sys.argv[1] == "parse":
        try:
            pp = dnssec_policy(sys.argv[2], write_tables=True, debug=True)
            print(pp.named_policy["default"])
            print(pp.policy("nonexistent.zone"))
        except Exception as e:
            print(e.args[0])