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|
--[[
Copyright (c) 2016, Andrew Lewis <nerf@judo.za.org>
Copyright (c) 2017, Vsevolod Stakhov <vsevolod@highsecure.ru>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
]]--
local exports = {}
local E = {}
local lua_util = require "lua_util"
local rspamd_util = require "rspamd_util"
local logger = require "rspamd_logger"
local fun = require "fun"
local function check_violation(N, task, domain)
-- Check for DKIM_REJECT
local sym_check = 'R_DKIM_REJECT'
if N == 'arc' then sym_check = 'ARC_REJECT' end
if task:has_symbol(sym_check) then
local sym = task:get_symbol(sym_check)[1]
logger.infox(task, 'skip signing for %s: violation %s found: %s',
domain, sym_check, sym.options)
return false
end
return true
end
local function insert_or_update_prop(N, task, p, prop, origin, data)
if #p == 0 then
local k = {}
k[prop] = data
table.insert(p, k)
lua_util.debugm(N, task, 'add %s "%s" using %s', prop, data, origin)
else
for _, k in ipairs(p) do
if not k[prop] then
k[prop] = data
lua_util.debugm(N, task, 'set %s to "%s" using %s', prop, data, origin)
end
end
end
end
local function get_mempool_selectors(N, task)
local p = {}
local key_var = "dkim_key"
local selector_var = "dkim_selector"
if N == "arc" then
key_var = "arc_key"
selector_var = "arc_selector"
end
p.key = task:get_mempool():get_variable(key_var)
p.selector = task:get_mempool():get_variable(selector_var)
if (not p.key or not p.selector) then
return false, {}
end
lua_util.debugm(N, task, 'override selector and key to %s:%s', p.key, p.selector)
return true, p
end
local function parse_dkim_http_headers(N, task, settings)
-- Configure headers
local headers = {
sign_header = settings.http_sign_header or "PerformDkimSign",
sign_on_reject_header = settings.http_sign_on_reject_header_header or 'SignOnAuthFailed',
domain_header = settings.http_domain_header or 'DkimDomain',
selector_header = settings.http_selector_header or 'DkimSelector',
key_header = settings.http_key_header or 'DkimPrivateKey'
}
if task:get_request_header(headers.sign_header) then
local domain = task:get_request_header(headers.domain_header)
local selector = task:get_request_header(headers.selector_header)
local key = task:get_request_header(headers.key_header)
if not (domain and selector and key) then
logger.errx(task, 'missing required headers to sign email')
return false,{}
end
-- Now check if we need to check the existing auth
local hdr = task:get_request_header(headers.sign_on_reject_header)
if not hdr or tostring(hdr) == '0' or tostring(hdr) == 'false' then
if not check_violation(N, task, domain, selector) then
return false, {}
end
end
local p = {}
local k = {
domain = tostring(domain),
rawkey = tostring(key),
selector = tostring(selector),
}
table.insert(p, k)
return true, p
end
lua_util.debugm(N, task, 'no sign header %s', headers.sign_header)
return false,{}
end
local function prepare_dkim_signing(N, task, settings)
local is_local, is_sign_networks, is_authed
if settings.use_http_headers then
local res,tbl = parse_dkim_http_headers(N, task, settings)
if not res then
if not settings.allow_headers_fallback then
return res,{}
else
lua_util.debugm(N, task, 'failed to read http headers, fallback to normal schema')
end
else
return res,tbl
end
end
if settings.sign_condition and type(settings.sign_condition) == 'function' then
-- Use sign condition only
local ret = settings.sign_condition(task)
if not ret then
return false,{}
end
if ret[1] then
return true,ret
else
return true,{ret}
end
end
local auser = task:get_user()
local ip = task:get_from_ip()
if ip and ip:is_local() then
is_local = true
end
if settings.sign_authenticated and auser then
lua_util.debugm(N, task, 'user is authenticated')
is_authed = true
elseif (settings.sign_networks and settings.sign_networks:get_key(ip)) then
is_sign_networks = true
lua_util.debugm(N, task, 'mail is from address in sign_networks')
elseif settings.sign_local and is_local then
lua_util.debugm(N, task, 'mail is from local address')
elseif settings.sign_inbound and not is_local and not auser then
lua_util.debugm(N, task, 'mail was sent to us')
else
lua_util.debugm(N, task, 'mail is ineligible for signing')
return false,{}
end
local efrom = task:get_from('smtp')
local empty_envelope = false
if #(((efrom or E)[1] or E).addr or '') == 0 then
if not settings.allow_envfrom_empty then
lua_util.debugm(N, task, 'empty envelope from not allowed')
return false,{}
else
empty_envelope = true
end
end
local hfrom = task:get_from('mime')
if not settings.allow_hdrfrom_multiple and (hfrom or E)[2] then
lua_util.debugm(N, task, 'multiple header from not allowed')
return false,{}
end
local eto = task:get_recipients(0)
local dkim_domain
local hdom = ((hfrom or E)[1] or E).domain
local edom = ((efrom or E)[1] or E).domain
local tdom = ((eto or E)[1] or E).domain
local udom = string.match(auser or '', '.*@(.*)')
local function get_dkim_domain(dtype)
if settings[dtype] == 'header' then
return hdom
elseif settings[dtype] == 'envelope' then
return edom
elseif settings[dtype] == 'auth' then
return udom
elseif settings[dtype] == 'recipient' then
return tdom
else
return settings[dtype]:lower()
end
end
local function is_skip_sign()
return not (settings.sign_networks and is_sign_networks) and
not (settings.sign_authenticated and is_authed) and
not (settings.sign_local and is_local)
end
if hdom then
hdom = hdom:lower()
end
if edom then
edom = edom:lower()
end
if udom then
udom = udom:lower()
end
if tdom then
tdom = tdom:lower()
end
if settings.signing_table and (settings.key_table or settings.use_vault) then
-- OpenDKIM style
if is_skip_sign() then
lua_util.debugm(N, task,
'skip signing: is_sign_network: %s, is_authed: %s, is_local: %s',
is_sign_networks, is_authed, is_local)
return false,{}
end
if not hfrom or not hfrom[1] or not hfrom[1].addr then
lua_util.debugm(N, task,
'signing_table: cannot get data when no header from is presented')
return false,{}
end
local sign_entry = settings.signing_table:get_key(hfrom[1].addr)
if sign_entry then
-- Check opendkim style entries
lua_util.debugm(N, task,
'signing_table: found entry for %s: %s', hfrom[1].addr, sign_entry)
if sign_entry == '%' then
sign_entry = hdom
end
if settings.key_table then
-- Now search in key table
local key_entry = settings.key_table:get_key(sign_entry)
if key_entry then
local parts = lua_util.str_split(key_entry, ':')
if #parts == 2 then
-- domain + key
local selector = settings.selector
if not selector then
logger.errx(task, 'no selector defined for sign_entry %s, key_entry %s',
sign_entry, key_entry)
return false,{}
end
local res = {
selector = selector,
domain = parts[1]:gsub('%%', hdom)
}
local st = parts[2]:sub(1, 2)
if st:sub(1, 1) == '/' or st == './' or st == '..' then
res.key = parts[2]:gsub('%%', hdom)
lua_util.debugm(N, task, 'perform dkim signing for %s, selector=%s, domain=%s, key file=%s',
hdom, selector, res.domain, res.key)
else
res.rawkey = parts[2] -- No sanity check here
lua_util.debugm(N, task, 'perform dkim signing for %s, selector=%s, domain=%s, raw key used',
hdom, selector, res.domain)
end
return true,{res}
elseif #parts == 3 then
-- domain, selector, key
local selector = parts[2]
local res = {
selector = selector,
domain = parts[1]:gsub('%%', hdom)
}
local st = parts[3]:sub(1, 2)
if st:sub(1, 1) == '/' or st == './' or st == '..' then
res.key = parts[3]:gsub('%%', hdom)
lua_util.debugm(N, task, 'perform dkim signing for %s, selector=%s, domain=%s, key file=%s',
hdom, selector, res.domain, res.key)
else
res.rawkey = parts[3] -- No sanity check here
lua_util.debugm(N, task, 'perform dkim signing for %s, selector=%s, domain=%s, raw key used',
hdom, selector, res.domain)
end
return true,{res}
else
logger.errx(task, 'invalid key entry for sign entry %s: %s; when signing %s domain',
sign_entry, key_entry, hdom)
return false,{}
end
elseif settings.use_vault then
-- Sign table is presented, the rest is covered by vault
lua_util.debugm(N, task, 'check vault for %s, by sign entry %s, key entry is missing',
hdom, sign_entry)
return true, {
domain = sign_entry,
vault = true
}
else
logger.errx(task, 'missing key entry for sign entry %s; when signing %s domain',
sign_entry, hdom)
return false,{}
end
else
logger.errx(task, 'cannot get key entry for signing entry %s, when signing %s domain',
sign_entry, hdom)
return false,{}
end
else
lua_util.debugm(N, task,
'signing_table: no entry for %s', hfrom[1].addr)
return false,{}
end
else
if settings.use_domain_sign_networks and is_sign_networks then
dkim_domain = get_dkim_domain('use_domain_sign_networks')
lua_util.debugm(N, task,
'sign_networks: use domain(%s) for signature: %s',
settings.use_domain_sign_networks, dkim_domain)
elseif settings.use_domain_sign_local and is_local then
dkim_domain = get_dkim_domain('use_domain_sign_local')
lua_util.debugm(N, task, 'local: use domain(%s) for signature: %s',
settings.use_domain_sign_local, dkim_domain)
elseif settings.use_domain_sign_inbound and not is_local and not auser then
dkim_domain = get_dkim_domain('use_domain_sign_inbound')
lua_util.debugm(N, task, 'inbound: use domain(%s) for signature: %s',
settings.use_domain_sign_inbound, dkim_domain)
elseif settings.use_domain_custom then
if type(settings.use_domain_custom) == 'string' then
-- Load custom function
local loadstring = loadstring or load
local ret, res_or_err = pcall(loadstring(settings.use_domain_custom))
if ret then
if type(res_or_err) == 'function' then
settings.use_domain_custom = res_or_err
dkim_domain = settings.use_domain_custom(task)
lua_util.debugm(N, task, 'use custom domain for signing: %s',
dkim_domain)
else
logger.errx(task, 'cannot load dkim domain custom script: invalid type: %s, expected function',
type(res_or_err))
settings.use_domain_custom = nil
end
else
logger.errx(task, 'cannot load dkim domain custom script: %s', res_or_err)
settings.use_domain_custom = nil
end
else
dkim_domain = settings.use_domain_custom(task)
lua_util.debugm(N, task, 'use custom domain for signing: %s',
dkim_domain)
end
else
dkim_domain = get_dkim_domain('use_domain')
lua_util.debugm(N, task, 'use domain(%s) for signature: %s',
settings.use_domain, dkim_domain)
end
end
if not dkim_domain then
lua_util.debugm(N, task, 'could not extract dkim domain')
return false,{}
end
if settings.use_esld then
dkim_domain = rspamd_util.get_tld(dkim_domain)
if hdom then
hdom = rspamd_util.get_tld(hdom)
end
if edom then
edom = rspamd_util.get_tld(edom)
end
end
lua_util.debugm(N, task, 'final DKIM domain: %s', dkim_domain)
-- Sanity checks
if edom and hdom and not settings.allow_hdrfrom_mismatch and hdom ~= edom then
if settings.allow_hdrfrom_mismatch_local and is_local then
lua_util.debugm(N, task, 'domain mismatch allowed for local IP: %1 != %2', hdom, edom)
elseif settings.allow_hdrfrom_mismatch_sign_networks and is_sign_networks then
lua_util.debugm(N, task, 'domain mismatch allowed for sign_networks: %1 != %2', hdom, edom)
else
if empty_envelope and hdom then
lua_util.debugm(N, task, 'domain mismatch allowed for empty envelope: %1 != %2', hdom, edom)
else
lua_util.debugm(N, task, 'domain mismatch not allowed: %1 != %2', hdom, edom)
return false,{}
end
end
end
if auser and not settings.allow_username_mismatch then
if not udom then
lua_util.debugm(N, task, 'couldnt find domain in username')
return false,{}
end
if settings.use_esld then
udom = rspamd_util.get_tld(udom)
end
if udom ~= dkim_domain then
lua_util.debugm(N, task, 'user domain mismatch')
return false,{}
end
end
local p = {}
if settings.use_vault then
if settings.vault_domains then
if settings.vault_domains:get_key(dkim_domain) then
return true, {
domain = dkim_domain,
vault = true,
}
else
lua_util.debugm(N, task, 'domain %s is not designated for vault',
dkim_domain)
return false,{}
end
else
-- TODO: try every domain in the vault
return true, {
domain = dkim_domain,
vault = true,
}
end
end
if settings.domain[dkim_domain] then
-- support old style selector/paths
if settings.domain[dkim_domain].selector or
settings.domain[dkim_domain].path then
local k = {}
k.selector = settings.domain[dkim_domain].selector
k.key = settings.domain[dkim_domain].path
table.insert(p, k)
end
for _, s in ipairs((settings.domain[dkim_domain].selectors or {})) do
lua_util.debugm(N, task, 'adding selector: %1', s)
local k = {}
k.selector = s.selector
k.key = s.path
table.insert(p, k)
end
end
if #p == 0 then
local ret, k = get_mempool_selectors(N, task)
if ret then
table.insert(p, k)
lua_util.debugm(N, task, 'using mempool selector %s with key %s',
k.selector, k.key)
end
end
if settings.selector_map then
local data = settings.selector_map:get_key(dkim_domain)
if data then
insert_or_update_prop(N, task, p, 'selector', 'selector_map', data)
else
lua_util.debugm(N, task, 'no selector in map for %s', dkim_domain)
end
end
if settings.path_map then
local data = settings.path_map:get_key(dkim_domain)
if data then
insert_or_update_prop(N, task, p, 'key', 'path_map', data)
else
lua_util.debugm(N, task, 'no key in map for %s', dkim_domain)
end
end
if #p == 0 and not settings.try_fallback then
lua_util.debugm(N, task, 'dkim unconfigured and fallback disabled')
return false,{}
end
if not settings.use_redis then
insert_or_update_prop(N, task, p, 'key',
'default path', settings.path)
end
insert_or_update_prop(N, task, p, 'selector',
'default selector', settings.selector)
if settings.check_violation then
if not check_violation(N, task, p.domain) then
return false,{}
end
end
insert_or_update_prop(N, task, p, 'domain', 'dkim_domain',
dkim_domain)
return true,p
end
exports.prepare_dkim_signing = prepare_dkim_signing
exports.sign_using_redis = function(N, task, settings, selectors, sign_func, err_func)
local lua_redis = require "lua_redis"
local function try_redis_key(selector, p)
p.key = nil
p.selector = selector
local rk = string.format('%s.%s', p.selector, p.domain)
local function redis_key_cb(err, data)
if err then
err_func(string.format("cannot make request to load DKIM key for %s: %s",
rk, err))
elseif type(data) ~= 'string' then
lua_util.debugm(N, task, "missing DKIM key for %s", rk)
else
p.rawkey = data
lua_util.debugm(N, task, 'found and parsed key for %s:%s in Redis',
p.domain, p.selector)
sign_func(task, p)
end
end
local rret = lua_redis.redis_make_request(task,
settings.redis_params, -- connect params
rk, -- hash key
false, -- is write
redis_key_cb, --callback
'HGET', -- command
{settings.key_prefix, rk} -- arguments
)
if not rret then
err_func(task,
string.format( "cannot make request to load DKIM key for %s", rk))
end
end
for _, p in ipairs(selectors) do
if settings.selector_prefix then
logger.infox(task, "using selector prefix '%s' for domain '%s'",
settings.selector_prefix, p.domain);
local function redis_selector_cb(err, data)
if err or type(data) ~= 'string' then
err_func(task, string.format("cannot make request to load DKIM selector for domain %s: %s",
p.domain, err))
else
try_redis_key(data, p)
end
end
local rret = lua_redis.redis_make_request(task,
settings.redis_params, -- connect params
p.domain, -- hash key
false, -- is write
redis_selector_cb, --callback
'HGET', -- command
{settings.selector_prefix, p.domain} -- arguments
)
if not rret then
err_func(task, string.format("cannot make Redis request to load DKIM selector for domain %s",
p.domain))
end
else
try_redis_key(p.selector, p)
end
end
end
exports.sign_using_vault = function(N, task, settings, selectors, sign_func, err_func)
local http = require "rspamd_http"
local ucl = require "ucl"
local full_url = string.format('%s/v1/%s/%s',
settings.vault_url, settings.vault_path or 'dkim', selectors.domain)
local function vault_callback(err, code, body, _)
if code ~= 200 then
err_func(task, string.format('cannot request data from the vault url: %s; %s (%s)',
full_url, err, body))
else
local parser = ucl.parser()
local res,parser_err = parser:parse_string(body)
if not res then
err_func(task, string.format('vault reply for %s (data=%s) cannot be parsed: %s',
full_url, body, parser_err))
else
local obj = parser:get_object()
if not obj or not obj.data then
err_func(task, string.format('vault reply for %s (data=%s) is invalid, no data',
full_url, body))
else
local elts = obj.data.selectors or {}
-- Filter selectors by time/sanity
local function is_selector_valid(p)
if not p.key or not p.selector then
return false
end
if p.valid_start then
-- Check start time
if rspamd_util.get_time() < tonumber(p.valid_start) then
return false
end
end
if p.valid_end then
if rspamd_util.get_time() >= tonumber(p.valid_end) then
return false
end
end
return true
end
fun.each(function(p)
local dkim_sign_data = {
rawkey = p.key,
selector = p.selector,
domain = p.domain or selectors.domain,
alg = p.alg,
}
lua_util.debugm(N, task, 'found and parsed key for %s:%s in Vault',
dkim_sign_data.domain, dkim_sign_data.selector)
sign_func(task, dkim_sign_data)
end, fun.filter(is_selector_valid, elts))
end
end
end
end
local ret = http.request{
task = task,
url = full_url,
callback = vault_callback,
timeout = settings.http_timeout or 5.0,
no_ssl_verify = settings.no_ssl_verify,
keepalive = true,
headers = {
['X-Vault-Token'] = settings.vault_token,
},
}
if not ret then
err_func(task, string.format("cannot make HTTP request to load DKIM data domain %s",
selectors.domain))
end
end
exports.validate_signing_settings = function(settings)
return settings.use_redis or
settings.path or
settings.domain or
settings.path_map or
settings.selector_map or
settings.use_http_headers or
(settings.signing_table and settings.key_table) or
(settings.use_vault and settings.vault_url and settings.vault_token) or
settings.sign_condition
end
exports.process_signing_settings = function(N, settings, opts)
local lua_maps = require "lua_maps"
for k,v in pairs(opts) do
if k == 'sign_networks' then
settings[k] = lua_maps.map_add(N, k, 'radix', 'DKIM signing networks')
elseif k == 'path_map' then
settings[k] = lua_maps.map_add(N, k, 'map', 'Paths to DKIM signing keys')
elseif k == 'selector_map' then
settings[k] = lua_maps.map_add(N, k, 'map', 'DKIM selectors')
elseif k == 'signing_table' then
settings[k] = lua_maps.map_add(N, k, 'glob', 'DKIM signing table')
elseif k == 'key_table' then
settings[k] = lua_maps.map_add(N, k, 'glob', 'DKIM keys table')
elseif k == 'vault_domains' then
settings[k] = lua_maps.map_add(N, k, 'glob', 'DKIM signing domains in vault')
elseif k == 'sign_condition' then
local ret,f = lua_util.callback_from_string(v)
if ret then
settings[k] = f
else
logger.errx(rspamd_config, 'cannot load sign condition %s: %s', v, f)
end
elseif k == 'whitelisted_signers_map' then
settings[k] = lua_maps.map_add(N, k, 'set', 'ARC trusted signers domains')
else
settings[k] = v
end
end
end
return exports
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