298 lines
11 KiB
Python
Executable File
298 lines
11 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# caclmgrd
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#
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# Control plane ACL manager daemon for SONiC
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#
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# Upon starting, this daemon reads control plane ACL tables and rules from
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# Config DB, converts the rules into iptables rules and installs the iptables
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# rules. The daemon then indefintely listens for notifications from Config DB
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# and updates iptables rules if control plane ACL configuration has changed.
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#
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try:
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import ipaddr as ipaddress
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import os
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import subprocess
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import sys
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import syslog
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from swsssdk import ConfigDBConnector
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except ImportError as err:
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raise ImportError("%s - required module not found" % str(err))
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VERSION = "1.0"
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SYSLOG_IDENTIFIER = "caclmgrd"
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# ========================== Syslog wrappers ==========================
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def log_info(msg):
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syslog.openlog(SYSLOG_IDENTIFIER)
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syslog.syslog(syslog.LOG_INFO, msg)
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syslog.closelog()
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def log_warning(msg):
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syslog.openlog(SYSLOG_IDENTIFIER)
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syslog.syslog(syslog.LOG_WARNING, msg)
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syslog.closelog()
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def log_error(msg):
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syslog.openlog(SYSLOG_IDENTIFIER)
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syslog.syslog(syslog.LOG_ERR, msg)
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syslog.closelog()
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# ============================== Classes ==============================
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class ControlPlaneAclManager(object):
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"""
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Class which reads control plane ACL tables and rules from Config DB,
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translates them into equivalent iptables commands and runs those
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commands in order to apply the control plane ACLs.
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Attributes:
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config_db: Handle to Config Redis database via SwSS SDK
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"""
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ACL_TABLE = "ACL_TABLE"
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ACL_RULE = "ACL_RULE"
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ACL_TABLE_TYPE_CTRLPLANE = "CTRLPLANE"
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# To specify a port range, use iptables format: separate start and end
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# ports with a colon, e.g., "1000:2000"
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ACL_SERVICES = {
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"NTP": {"ip_protocols": ["udp"], "dst_ports": ["123"]},
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"SNMP": {"ip_protocols": ["tcp", "udp"], "dst_ports": ["161"]},
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"SSH": {"ip_protocols": ["tcp"], "dst_ports": ["22"]}
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}
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def __init__(self):
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# Open a handle to the Config database
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self.config_db = ConfigDBConnector()
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self.config_db.connect()
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def run_commands(self, commands):
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"""
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Given a list of shell commands, run them in order
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Args:
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commands: List of strings, each string is a shell command
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"""
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for cmd in commands:
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proc = subprocess.Popen(cmd, shell=True)
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(stdout, stderr) = proc.communicate()
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if proc.returncode != 0:
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log_error("Error running command '{}'".format(cmd))
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def parse_int_to_tcp_flags(self, hex_value):
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tcp_flags_str = ""
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if hex_value & 0x01:
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tcp_flags_str += "FIN,"
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if hex_value & 0x02:
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tcp_flags_str += "SYN,"
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if hex_value & 0x04:
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tcp_flags_str += "RST,"
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if hex_value & 0x08:
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tcp_flags_str += "PSH,"
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if hex_value & 0x10:
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tcp_flags_str += "ACK,"
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if hex_value & 0x20:
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tcp_flags_str += "URG,"
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# iptables doesn't handle the flags below now. It has some special keys for it:
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# --ecn-tcp-cwr This matches if the TCP ECN CWR (Congestion Window Received) bit is set.
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# --ecn-tcp-ece This matches if the TCP ECN ECE (ECN Echo) bit is set.
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# if hex_value & 0x40:
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# tcp_flags_str += "ECE,"
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# if hex_value & 0x80:
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# tcp_flags_str += "CWR,"
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# Delete the trailing comma
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tcp_flags_str = tcp_flags_str[:-1]
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return tcp_flags_str
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def get_acl_rules_and_translate_to_iptables_commands(self):
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"""
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Retrieves current ACL tables and rules from Config DB, translates
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control plane ACLs into a list of iptables commands that can be run
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in order to install ACL rules.
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Returns:
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A list of strings, each string is an iptables shell command
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"""
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iptables_cmds = []
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# First, add iptables commands to set default policies to accept all
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# traffic. In case we are connected remotely, the connection will not
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# drop when we flush the current rules
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iptables_cmds.append("iptables -P INPUT ACCEPT")
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iptables_cmds.append("iptables -P FORWARD ACCEPT")
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iptables_cmds.append("iptables -P OUTPUT ACCEPT")
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# Add iptables command to flush the current rules
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iptables_cmds.append("iptables -F")
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# Add iptables command to delete all non-default chains
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iptables_cmds.append("iptables -X")
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# Add same set of commands for ip6tables
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iptables_cmds.append("ip6tables -P INPUT ACCEPT")
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iptables_cmds.append("ip6tables -P FORWARD ACCEPT")
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iptables_cmds.append("ip6tables -P OUTPUT ACCEPT")
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iptables_cmds.append("ip6tables -F")
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iptables_cmds.append("ip6tables -X")
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# Add iptables commands to allow all IPv4 and IPv6 traffic from localhost
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iptables_cmds.append("iptables -A INPUT -s 127.0.0.1 -i lo -j ACCEPT")
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iptables_cmds.append("ip6tables -A INPUT -s ::1 -i lo -j ACCEPT")
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# Get current ACL tables and rules from Config DB
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self._tables_db_info = self.config_db.get_table(self.ACL_TABLE)
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self._rules_db_info = self.config_db.get_table(self.ACL_RULE)
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# Walk the ACL tables
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for (table_name, table_data) in self._tables_db_info.iteritems():
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table_ip_version = None
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# Ignore non-control-plane ACL tables
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if table_data["type"] != self.ACL_TABLE_TYPE_CTRLPLANE:
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continue
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acl_services = table_data["services"]
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for acl_service in acl_services:
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if acl_service not in self.ACL_SERVICES:
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log_warning("Ignoring control plane ACL '{}' with unrecognized service '{}'"
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.format(table_name, acl_service))
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continue
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log_info("Translating ACL rules for control plane ACL '{}' (service: '{}')"
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.format(table_name, acl_service))
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# Obtain default IP protocol(s) and destination port(s) for this service
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ip_protocols = self.ACL_SERVICES[acl_service]["ip_protocols"]
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dst_ports = self.ACL_SERVICES[acl_service]["dst_ports"]
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acl_rules = {}
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for ((rule_table_name, rule_id), rule_props) in self._rules_db_info.iteritems():
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if rule_table_name == table_name:
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if not rule_props:
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log_warning("rule_props for rule_id {} empty or null!".format(rule_id))
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continue
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try:
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acl_rules[rule_props["PRIORITY"]] = rule_props
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except KeyError:
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log_error("rule_props for rule_id {} does not have key 'PRIORITY'!".format(rule_id))
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continue
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# If we haven't determined the IP version for this ACL table yet,
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# try to do it now. We determine heuristically based on whether the
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# src IP is an IPv4 or IPv6 address.
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if not table_ip_version and "SRC_IP" in rule_props and rule_props["SRC_IP"]:
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ip_addr = ipaddress.IPAddress(rule_props["SRC_IP"].split("/")[0])
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if isinstance(ip_addr, ipaddress.IPv6Address):
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table_ip_version = 6
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elif isinstance(ip_addr, ipaddress.IPv4Address):
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table_ip_version = 4
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# If we were unable to determine whether this ACL table contains
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# IPv4 or IPv6 rules, log a message and skip processing this table.
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if not table_ip_version:
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log_warning("Unable to determine if ACL table '{}' contains IPv4 or IPv6 rules. Skipping table..."
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.format(table_name))
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continue
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# For each ACL rule in this table (in descending order of priority)
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for priority in sorted(acl_rules.iterkeys(), reverse=True):
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rule_props = acl_rules[priority]
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if "PACKET_ACTION" not in rule_props:
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log_error("ACL rule does not contain PACKET_ACTION property")
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continue
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# Apply the rule to the default protocol(s) for this ACL service
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for ip_protocol in ip_protocols:
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for dst_port in dst_ports:
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rule_cmd = "ip6tables" if table_ip_version == 6 else "iptables"
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rule_cmd += " -A INPUT -p {}".format(ip_protocol)
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if "SRC_IP" in rule_props and rule_props["SRC_IP"]:
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rule_cmd += " -s {}".format(rule_props["SRC_IP"])
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rule_cmd += " --dport {}".format(dst_port)
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# If there are TCP flags present and ip protocol is TCP, append them
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if ip_protocol == "tcp" and "TCP_FLAGS" in rule_props and rule_props["TCP_FLAGS"]:
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tcp_flags, tcp_flags_mask = rule_props["TCP_FLAGS"].split("/")
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tcp_flags = int(tcp_flags, 16)
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tcp_flags_mask = int(tcp_flags_mask, 16)
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if tcp_flags_mask > 0:
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rule_cmd += " --tcp-flags {mask} {flags}".format(mask = self.parse_int_to_tcp_flags(tcp_flags_mask), flags = self.parse_int_to_tcp_flags(tcp_flags))
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# Append the packet action as the jump target
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rule_cmd += " -j {}".format(rule_props["PACKET_ACTION"])
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iptables_cmds.append(rule_cmd)
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return iptables_cmds
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def update_control_plane_acls(self):
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"""
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Convenience wrapper which retrieves current ACL tables and rules from
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Config DB, translates control plane ACLs into a list of iptables
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commands and runs them.
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"""
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iptables_cmds = self.get_acl_rules_and_translate_to_iptables_commands()
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log_info("Issuing the following iptables commands:")
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for cmd in iptables_cmds:
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log_info(" " + cmd)
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self.run_commands(iptables_cmds)
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def notification_handler(self, key, data):
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log_info("ACL configuration changed. Updating iptables rules for control plane ACLs...")
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self.update_control_plane_acls()
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def run(self):
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# Unconditionally update control plane ACLs once at start
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self.update_control_plane_acls()
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# Subscribe to notifications when ACL tables or rules change
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self.config_db.subscribe(self.ACL_TABLE,
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lambda table, key, data: self.notification_handler(key, data))
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self.config_db.subscribe(self.ACL_RULE,
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lambda table, key, data: self.notification_handler(key, data))
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# Indefinitely listen for Config DB notifications
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self.config_db.listen()
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# ============================= Functions =============================
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def main():
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log_info("Starting up...")
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if not os.geteuid() == 0:
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log_error("Must be root to run this daemon")
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print "Error: Must be root to run this daemon"
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sys.exit(1)
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# Instantiate a ControlPlaneAclManager object
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caclmgr = ControlPlaneAclManager()
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caclmgr.run()
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if __name__ == "__main__":
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main()
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