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--[[
Filter module for Alpine Wall
Copyright (C) 2012 Kaarle Ritvanen
Licensed under the terms of GPL2
]]--
module(..., package.seeall)
require 'awall'
require 'awall.host'
require 'awall.model'
require 'awall.optfrag'
require 'awall.util'
local model = awall.model
local combinations = awall.optfrag.combinations
local Filter = model.class(model.Rule)
function Filter:defaultzones()
return self.dnat and {nil} or model.Rule.defaultzones(self)
end
function Filter:destoptfrags()
local ofrags = model.Rule.destoptfrags(self)
if not self.dnat then return ofrags end
ofrags = combinations(ofrags, {{family='inet6'}})
local natof = self:create(model.Zone, {addr=self.dnat}):optfrags('out')
assert(#natof == 1)
table.insert(ofrags, natof[1])
return ofrags
end
function Filter:trules()
local res = {}
local function extrarules(cls, extra)
local params = {}
for i, attr in ipairs({'in', 'out', 'src', 'dest',
'ipset', 'ipsec', 'service'}) do
params[attr] = self[attr]
end
if extra then for k, v in pairs(extra) do params[k] = v end end
return awall.util.extend(res, self:create(cls, params):trules())
end
if self.dnat then
if self.action ~= 'accept' then
self:error('dnat option not allowed with '..self.action..' action')
end
if not self.dest then
self:error('Destination address must be specified with DNAT')
end
if string.find(self.dnat, '/') then
self:error('DNAT target cannot be a network address')
end
for i, attr in ipairs({'ipsec', 'ipset'}) do
if self[attr] then
self:error('dnat and '..attr..' options cannot be used simultaneously')
end
end
local dnataddr
for i, addr in ipairs(awall.host.resolve(self.dnat, self)) do
if addr[1] == 'inet' then
if dnataddr then
self:error(self.dnat..' resolves to multiple IPv4 addresses')
end
dnataddr = addr[2]
end
end
if not dnataddr then
self:error(self.dnat..' does not resolve to any IPv4 address')
end
extrarules('dnat', {['ip-range']=dnataddr, out=nil})
end
if self.action == 'tarpit' then extrarules('no-track') end
awall.util.extend(res, model.Rule.trules(self))
return res
end
function Filter:limit()
local res
for i, limit in ipairs({'conn-limit', 'flow-limit'}) do
if self[limit] then
if res then
self:error('Cannot specify multiple limits for a single filter rule')
end
res = limit
end
end
return res
end
function Filter:position()
return self:limit() == 'flow-limit' and 'prepend' or 'append'
end
function Filter:target()
if not self:limit() then return model.Rule.target(self) end
return self:newchain('limit')
end
function Filter:extraoptfrags()
local res = {}
local limit = self:limit()
if limit then
if self.action ~= 'accept' then
self:error('Cannot specify limit for '..self.action..' filter')
end
local optbase = '-m recent --name '..self:target()
table.insert(res, {chain=self:target(),
opts=optbase..' --update --hitcount '..self[limit].count..' --seconds '..self[limit].interval,
target='logdrop'})
table.insert(res, {chain=self:target(),
opts=optbase..' --set',
target='ACCEPT'})
end
return res
end
local Policy = model.class(Filter)
function Policy:servoptfrags() return nil end
classes = {{'filter', Filter},
{'policy', Policy}}
defrules = {}
local dar = combinations({{chain='FORWARD'}, {chain='INPUT'}, {chain='OUTPUT'}},
{{opts='-m state --state RELATED,ESTABLISHED'}})
for i, chain in ipairs({'INPUT', 'OUTPUT'}) do
table.insert(dar,
{chain=chain,
opts='-'..string.lower(string.sub(chain, 1, 1))..' lo'})
end
defrules.pre = combinations(combinations(dar,
{{table='filter', target='ACCEPT'}}),
{{family='inet'}, {family='inet6'}})
defrules['post-filter'] = combinations({{family='inet6',
table='filter',
opts='-p icmpv6',
target='ACCEPT'}},
{{chain='INPUT'}, {chain='OUTPUT'}})
achains = {}
local limitedlog = {opts='-m limit --limit 1/second', target='LOG'}
for i, target in ipairs({'drop', 'reject'}) do
util.extend(achains,
combinations({{chain='log'..target}},
{limitedlog, {target=string.upper(target)}}))
end
util.extend(achains,
combinations({{chain='tarpit'}},
{limitedlog,
{opts='-p tcp', target='TARPIT'},
{target='DROP'}}))
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