filter.lua 12 KB
Newer Older
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
1 2
--[[
Filter module for Alpine Wall
3
Copyright (C) 2012-2014 Kaarle Ritvanen
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
4
See LICENSE file for license details
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
5 6 7
]]--


Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
8
local loadclass = require('awall').loadclass
9
local resolve = require('awall.host')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
10

11
local model = require('awall.model')
12 13 14
local class = model.class
local Rule = model.Rule

15
local combinations = require('awall.optfrag').combinations
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
16

17
local util = require('awall.util')
18
local contains = util.contains
19
local extend = util.extend
20
local listpairs = util.listpairs
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
21 22


23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
local RECENT_MAX_COUNT = 20

local FilterLimit = class(model.Limit)

function FilterLimit:recentofrags(name)
   local count = self.count
   local interval = self.interval

   if count > RECENT_MAX_COUNT then
      count = self:rate()
      interval = 1
   end

   if count > RECENT_MAX_COUNT then return end

   local uofs = {}
   local sofs = {}

   for _, family in ipairs{'inet', 'inet6'} do
      if type(self.mask[family].mode) ~= 'table' then return end
      local mask = ''
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
44
      local attr, len = table.unpack(self.mask[family].mode)
45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

      if family == 'inet' then
	 local octet
	 for i = 0, 3 do
	    if len <= i * 8 then octet = 0
	    elseif len > i * 8 + 7 then octet = 255
	    else octet = 256 - 2^(8 - len % 8) end
	    mask = util.join(mask, '.', octet)
	 end

      elseif family == 'inet6' then
	 while len > 0 do
	    if #mask % 5 == 4 then mask = mask..':' end
	    mask = mask..('%x'):format(16 - 2^math.max(0, 4 - len))
	    len = len - 4
	 end
	 while #mask % 5 < 4 do mask = mask..'0' end
	 if #mask < 39 then mask = mask..'::' end
      end

      local rec = {
	 {
	    family=family,
	    opts='-m recent --name '..name..' --r'..
	       ({src='source', dest='dest'})[attr]..' --mask '..mask
	 }
      }

      extend(
	 uofs,
	 combinations(
	    rec,
	    {{opts='--update --hitcount '..count..' --seconds '..interval}}
	 )
      )
      extend(sofs, combinations(rec, {{opts='--set'}}))
   end

   return uofs, sofs
end


87 88 89 90 91 92 93 94
local TranslatingRule = class(Rule)

function TranslatingRule:destoptfrags()
   local ofrags = TranslatingRule.super(self):destoptfrags()
   if not self.dnat then return ofrags end

   ofrags = combinations(ofrags, {{family='inet6'}})
   local natof = self:create(
95
      model.Zone, {addr=self.dnat.addr}
96 97 98 99 100 101
   ):optfrags(self:direction('out'))
   assert(#natof == 1)
   table.insert(ofrags, natof[1])
   return ofrags
end

102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133
function TranslatingRule:servoptfrags()
   local ofrags = TranslatingRule.super(self):servoptfrags()
   if not (self.dnat and self.dnat.port) then return ofrags end

   ofrags = combinations(ofrags, {{family='inet6'}})

   local protos = {}
   for _, serv in listpairs(self.service) do
      for _, sdef in listpairs(serv) do
	 if sdef.family ~= 'inet6' then
	    if not contains({'tcp', 'udp'}, sdef.proto) then
	       self:error('Cannot do port translation for '..sdef.proto)
	    end
	    protos[sdef.proto] = true
	 end
      end
   end
   for proto, _ in pairs(protos) do
      extend(
	 ofrags,
	 combinations(
	    self:create(
	       model.Rule, {service={proto=proto, port=self.dnat.port}}
	    ):servoptfrags(),
	    {{family='inet'}}
	 )
      )
   end

   return ofrags
end

134

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
135 136 137 138
local LoggingRule = class(TranslatingRule)

function LoggingRule:init(...)
   LoggingRule.super(self):init(...)
139
   util.setdefault(self, 'action', 'accept')
140 141 142
   if type(self.log) ~= 'table' then
      self.log = loadclass('log').get(self, self.log, self.action ~= 'accept')
   end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
143 144 145 146 147
end

function LoggingRule:actiontarget() return 'ACCEPT' end

function LoggingRule:target()
148
   if self.log then return self:uniqueid('log'..self.action) end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
149 150 151 152 153
   return self:actiontarget()
end

function LoggingRule:logchain(log, action, target)
   if not log then return {}, target end
154
   local chain = self:uniqueid('log'..action)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
155 156 157 158 159

   local ofrags = log:optfrags()
   table.insert(ofrags, {target=target})

   return combinations({{chain=chain}}, ofrags), chain
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
160 161 162 163 164 165 166
end

function LoggingRule:extraoptfrags()
   return self:logchain(self.log, self.action, self:actiontarget())
end


167
local RelatedRule = class(TranslatingRule)
168 169 170 171 172 173 174 175

function RelatedRule:servoptfrags()
   local helpers = {}
   for i, serv in listpairs(self.service) do
      for i, sdef in listpairs(serv) do
	 local helper = sdef['ct-helper']
	 if helper then
	    helpers[helper] = {
176
	       family=sdef.family,
177
	       opts='-m conntrack --ctstate RELATED -m helper --helper '..helper
178 179 180 181 182 183 184
	    }
	 end
      end
   end
   return util.values(helpers)
end

185 186
function RelatedRule:target() return 'ACCEPT' end

187

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
188
local Filter = class(LoggingRule)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
189

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
190
function Filter:init(...)
191
   Filter.super(self):init(...)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
192 193

   -- alpine v2.4 compatibility
194
   if contains({'logdrop', 'logreject'}, self.action) then
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
195
      self:warning('Deprecated action: '..self.action)
196
      self.action = self.action:sub(4, -1)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
197 198 199
   end

   local limit = self:limit()
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
200
   if limit then
201 202 203
      if limit == 'conn-limit' and self['no-track'] then
	 self:error('Tracking required with connection limit')
      end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
204 205 206
      if type(self[limit]) ~= 'table' then
	 self[limit] = {count=self[limit]}
      end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
207
      self[limit].log = loadclass('log').get(self, self[limit].log, true)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
208
   end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
209 210
end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
211 212 213
function Filter:trules()
   local res = {}

214 215
   local function extrarules(label, cls, options)
      options = options or {}
216

217 218 219 220 221
      local params = {}
      for i, attr in ipairs(
	 {'in', 'out', 'src', 'dest', 'dnat', 'ipset', 'ipsec', 'service'}
      ) do
	 params[attr] = (options.src or self)[attr]
222
      end
223 224 225 226
      util.update(params, options.update)
      if options.discard then params[options.discard] = nil end

      extend(res, self:create(cls, params, label, options.index):trules())
227 228
   end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
229
   if self.dnat then
230 231 232
      if self.action ~= 'accept' then
	 self:error('dnat option not allowed with '..self.action..' action')
      end
233 234 235
      if self['no-track'] then
	 self:error('dnat option not allowed with no-track')
      end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
236 237
      for i, attr in ipairs({'ipsec', 'ipset'}) do
	 if self[attr] then
238
	    self:error('dnat and '..attr..' options cannot be used simultaneously')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
239 240 241
	 end
      end

242 243 244 245 246
      if type(self.dnat) == 'string' then self.dnat = {addr=self.dnat} end
      if self.dnat.addr:find('/') then
	 self:error('DNAT target cannot be a network address')
      end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
247
      local dnataddr
248
      for i, addr in ipairs(resolve(self.dnat.addr, self)) do
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
249 250
	 if addr[1] == 'inet' then
	    if dnataddr then
251 252 253
	       self:error(
		  self.dnat.addr..' resolves to multiple IPv4 addresses'
	       )
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
254 255 256 257 258
	    end
	    dnataddr = addr[2]
	 end
      end
      if not dnataddr then
259
	 self:error(self.dnat.addr..' does not resolve to any IPv4 address')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
260 261
      end

262 263 264 265 266 267 268 269
      extrarules(
	 'dnat',
	 'dnat',
	 {
	    update={['to-addr']=dnataddr, ['to-port']=self.dnat.port},
	    discard='out'
	 }
      )
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
270 271
   end

272
   if self.action == 'tarpit' or self['no-track'] then
273
      extrarules('no-track', 'no-track')
274
   end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
275

276
   extend(res, Filter.super(self):trules())
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
277

278
   if self.action == 'accept' then
279
      if self:position() == 'prepend' then
280
	 extrarules('final', LoggingRule, {update={log=self.log}})
281 282
      end

283 284 285 286
      local nr = #res

      if self.related then
	 for i, rule in listpairs(self.related) do
287
	    extrarules(
288 289 290
	       'related',
	       RelatedRule,
	       {index=i, src=rule, update={service=self.service}}
291
	    )
292 293 294 295
	 end
      else
	 -- TODO avoid creating unnecessary RELATED rules by introducing
	 -- helper direction attributes to service definitions
296
	 extrarules('related', RelatedRule)
297
	 extrarules('related-reply', RelatedRule, {update={reverse=true}})
298 299 300 301 302 303
      end

      if self['no-track'] then
	 if #res > nr then
	    self:error('Tracking required by service')
	 end
304 305
	 extrarules('no-track-reply', 'no-track', {update={reverse=true}})
	 extrarules('reply', 'filter', {update={reverse=true}})
306
      end
307 308
   end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
309 310 311
   return res
end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
312 313 314 315 316
function Filter:limit()
   local res
   for i, limit in ipairs({'conn-limit', 'flow-limit'}) do
      if self[limit] then
	 if res then
317
	    self:error('Cannot specify multiple limits for a single filter rule')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
318 319 320 321 322 323 324 325
	 end
	 res = limit
      end
   end
   return res
end

function Filter:position()
326 327
   return not self['no-track'] and self:limit() == 'flow-limit'
      and 'prepend' or 'append'
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
328 329
end

330 331
function Filter:actiontarget()
   if self.action == 'tarpit' then return 'tarpit' end
332
   if contains({'accept', 'drop', 'reject'}, self.action) then
333
      return self.action:upper()
334
   end
335
   self:error('Invalid filter action: '..self.action)
336 337
end

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
338
function Filter:target()
339
   if self:limit() then return self:uniqueid('limit') end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
340
   return Filter.super(self).target()
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
341 342 343 344 345 346
end

function Filter:extraoptfrags()
   local limit = self:limit()
   if limit then
      if self.action ~= 'accept' then
347
	 self:error('Cannot specify limit for '..self.action..' filter')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
348
      end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
349

350
      local limitchain = self:uniqueid('limit')
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
351
      local limitlog = self[limit].log
352
      local limitobj = self:create(FilterLimit, self[limit], 'limit')
353

354 355 356 357
      local ofrags = {}
      local logch, limitofs
      local accept = self:position() == 'append'

358
      local uofs, sofs = limitobj:recentofrags(limitchain)
359

360
      if uofs then
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
361
	 ofrags, logch = self:logchain(limitlog, 'drop', 'DROP')
362

363
	 limitofs = combinations(uofs, {{target=logch}})
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
364
	 if accept and self.log then extend(limitofs, self.log:optfrags()) end
365 366 367
	 extend(
	    limitofs, combinations(sofs, {{target=accept and 'ACCEPT' or nil}})
	 )
368 369 370 371 372 373

      else
	 if accept then
	    ofrags, logch = self:logchain(self.log, 'accept', 'ACCEPT')
	 else logch = 'RETURN' end

374 375 376
	 limitofs = combinations(
	    limitobj:limitofrags(limitchain), {{target=logch}}
	 )
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
377
	 if limitlog then extend(limitofs, limitlog:optfrags()) end
378
	 table.insert(limitofs, {target='DROP'})
379
      end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
380

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
381 382 383
      extend(ofrags, combinations({{chain=limitchain}}, limitofs))
      return ofrags
   end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
384

Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
385
   return Filter.super(self):extraoptfrags()
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
386 387 388
end


389
local Policy = class(Filter)
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
390 391 392 393

function Policy:servoptfrags() return nil end


394 395
local fchains = {{chain='FORWARD'}, {chain='INPUT'}, {chain='OUTPUT'}}

396
local function stateful(config)
397 398
   local res = {}

399 400 401 402 403
   for i, family in ipairs{'inet', 'inet6'} do

      local er = combinations(
	 fchains,
	 {{opts='-m conntrack --ctstate ESTABLISHED'}}
404
      )
405 406
      for i, chain in ipairs({'INPUT', 'OUTPUT'}) do
	 table.insert(
407
	    er, {chain=chain, opts='-'..chain:sub(1, 1):lower()..' lo'}
408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424
	 )
      end
      extend(
	 res,
	 combinations(er, {{family=family, table='filter', target='ACCEPT'}})
      )

      -- TODO avoid creating unnecessary CT rules by inspecting the
      -- filter rules' target families and chains
      local visited = {}
      local ofrags = {}
      for i, rule in listpairs(config.filter) do
	 for i, serv in listpairs(rule.service) do
	    if not visited[serv] then
	       for i, sdef in listpairs(serv) do
		  if sdef['ct-helper'] then
		     local of = combinations(
425
			Rule.morph{service={sdef}}:servoptfrags(),
426 427 428 429 430 431 432 433
			{{family=family}}
		     )
		     if of[1] then
			assert(#of == 1)
			of[1].target = 'CT --helper '..sdef['ct-helper']
			table.insert(ofrags, of[1])
		     end
		  end
434
	       end
435
	       visited[serv] = true
436 437 438
	    end
	 end
      end
439 440 441 442 443 444 445
      extend(
	 res,
	 combinations(
	    {{table='raw'}},
	    {{chain='PREROUTING'}, {chain='OUTPUT'}},
	    ofrags
	 )
446
      )
447
   end
448 449

   return res
450
end
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
451

452 453
local icmp = {{family='inet', table='filter', opts='-p icmp'}}
local icmp6 = {{family='inet6', table='filter', opts='-p icmpv6'}}
454 455 456 457 458 459 460
local ir = combinations(
   icmp6,
   {{chain='INPUT'}, {chain='OUTPUT'}},
   {{target='ACCEPT'}}
)
extend(ir, combinations(icmp6, {{chain='FORWARD', target='icmp-routing'}}))
extend(ir, combinations(icmp, fchains, {{target='icmp-routing'}}))
461 462

local function icmprules(ofrag, oname, types)
463 464 465 466 467 468 469 470 471
   extend(
      ir,
      combinations(ofrag,
		   {{chain='icmp-routing', target='ACCEPT'}},
		   util.map(types,
			    function(t)
			       return {opts='--'..oname..' '..t}
			    end))
   )
472 473 474
end
icmprules(icmp, 'icmp-type', {3, 11, 12})
icmprules(icmp6, 'icmpv6-type', {1, 2, 3, 4})
Kaarle Ritvanen's avatar
Kaarle Ritvanen committed
475

476 477 478 479 480 481 482 483 484 485
return {
   export={
      filter={class=Filter, before={'dnat', 'no-track'}},
      policy={class=Policy, after='%filter-after'},
      ['%filter-before']={rules=stateful, before='filter'},
      ['%filter-after']={rules=ir, after='filter'}
   },
   achains=combinations(
      {{chain='tarpit'}}, {{opts='-p tcp', target='TARPIT'}, {target='DROP'}}
   )
486
}