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--[[
Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com>
Copyright (c) 2015-2016, Andrew Lewis <nerf@judo.za.org>
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.
]]--
-- Common dmarc stuff
local rspamd_logger = require "rspamd_logger"
local lua_util = require "lua_util"
local N = "dmarc"
local exports = {}
exports.default_settings = {
auth_and_local_conf = false,
symbols = {
spf_allow_symbol = 'R_SPF_ALLOW',
spf_deny_symbol = 'R_SPF_FAIL',
spf_softfail_symbol = 'R_SPF_SOFTFAIL',
spf_neutral_symbol = 'R_SPF_NEUTRAL',
spf_tempfail_symbol = 'R_SPF_DNSFAIL',
spf_permfail_symbol = 'R_SPF_PERMFAIL',
spf_na_symbol = 'R_SPF_NA',
dkim_allow_symbol = 'R_DKIM_ALLOW',
dkim_deny_symbol = 'R_DKIM_REJECT',
dkim_tempfail_symbol = 'R_DKIM_TEMPFAIL',
dkim_na_symbol = 'R_DKIM_NA',
dkim_permfail_symbol = 'R_DKIM_PERMFAIL',
-- DMARC symbols
allow = 'DMARC_POLICY_ALLOW',
badpolicy = 'DMARC_BAD_POLICY',
dnsfail = 'DMARC_DNSFAIL',
na = 'DMARC_NA',
reject = 'DMARC_POLICY_REJECT',
softfail = 'DMARC_POLICY_SOFTFAIL',
quarantine = 'DMARC_POLICY_QUARANTINE',
},
no_sampling_domains = nil,
no_reporting_domains = nil,
reporting = {
report_local_controller = false, -- Store reports for local/controller scans (for testing only)
redis_keys = {
index_prefix = 'dmarc_idx',
report_prefix = 'dmarc_rpt',
join_char = ';',
},
helo = 'rspamd.localhost',
smtp = '127.0.0.1',
smtp_port = 25,
retries = 2,
from_name = 'Rspamd',
msgid_from = 'rspamd',
enabled = false,
max_entries = 1000,
keys_expire = 172800,
only_domains = nil,
},
actions = {},
}
-- Returns a key used to be inserted into dmarc report sample
exports.dmarc_report = function(task, settings, data)
local rspamd_lua_utils = require "lua_util"
local E = {}
local ip = task:get_from_ip()
if not ip or not ip:is_valid() then
rspamd_logger.infox(task, 'cannot store dmarc report for %s: no valid source IP',
data.domain)
return nil
end
ip = ip:to_string()
if rspamd_lua_utils.is_rspamc_or_controller(task) and not settings.reporting.report_local_controller then
rspamd_logger.infox(task, 'cannot store dmarc report for %s from IP %s: has come from controller/rspamc',
data.domain, ip)
return
end
local dkim_pass = table.concat(data.dkim_results.pass or E, '|')
local dkim_fail = table.concat(data.dkim_results.fail or E, '|')
local dkim_temperror = table.concat(data.dkim_results.temperror or E, '|')
local dkim_permerror = table.concat(data.dkim_results.permerror or E, '|')
local disposition_to_return = data.disposition
local res = table.concat({
ip, data.spf_ok, data.dkim_ok,
disposition_to_return, (data.sampled_out and 'sampled_out' or ''), data.domain,
dkim_pass, dkim_fail, dkim_temperror, dkim_permerror, data.spf_domain, data.spf_result }, ',')
return res
end
exports.gen_munging_callback = function(munging_opts, settings)
local rspamd_util = require "rspamd_util"
local lua_mime = require "lua_mime"
return function(task)
if munging_opts.mitigate_allow_only then
if not task:has_symbol(settings.symbols.allow) then
lua_util.debugm(N, task, 'skip munging, no %s symbol',
settings.symbols.allow)
-- Excepted
return
end
else
local has_dmarc = task:has_symbol(settings.symbols.allow) or
task:has_symbol(settings.symbols.quarantine) or
task:has_symbol(settings.symbols.reject) or
task:has_symbol(settings.symbols.softfail)
if not has_dmarc then
lua_util.debugm(N, task, 'skip munging, no %s symbol',
settings.symbols.allow)
-- Excepted
return
end
end
if munging_opts.mitigate_strict_only then
local s = task:get_symbol(settings.symbols.allow) or { [1] = {} }
local sopts = s[1].options or {}
local seen_strict
for _, o in ipairs(sopts) do
if o == 'reject' or o == 'quarantine' then
seen_strict = true
break
end
end
if not seen_strict then
lua_util.debugm(N, task, 'skip munging, no strict policy found in %s',
settings.symbols.allow)
-- Excepted
return
end
end
if munging_opts.munge_map_condition then
local accepted, trace = munging_opts.munge_map_condition:process(task)
if not accepted then
lua_util.debugm(N, task, 'skip munging, maps condition not satisfied: (%s)',
trace)
-- Excepted
return
end
end
-- Now, look for domain for munging
local mr = task:get_recipients({ 'mime', 'orig' })
local rcpt_found
if mr then
for _, r in ipairs(mr) do
if r.domain and munging_opts.list_map:get_key(r.addr) then
rcpt_found = r
break
end
end
end
if not rcpt_found then
lua_util.debugm(N, task, 'skip munging, recipients are not in list_map')
-- Excepted
return
end
local from = task:get_from({ 'mime', 'orig' })
if not from or not from[1] then
lua_util.debugm(N, task, 'skip munging, from is bad')
-- Excepted
return
end
from = from[1]
local via_user = rcpt_found.user
local via_addr = rcpt_found.addr
local via_name
if from.name == "" then
via_name = string.format('%s via %s', from.user or 'unknown', via_user)
else
via_name = string.format('%s via %s', from.name, via_user)
end
local hdr_encoded = rspamd_util.fold_header('From',
rspamd_util.mime_header_encode(string.format('%s <%s>',
via_name, via_addr)), task:get_newlines_type())
local orig_from_encoded = rspamd_util.fold_header('X-Original-From',
rspamd_util.mime_header_encode(string.format('%s <%s>',
from.name or '', from.addr)), task:get_newlines_type())
local add_hdrs = {
['From'] = { order = 1, value = hdr_encoded },
}
local remove_hdrs = { ['From'] = 0 }
local nreply = from.addr
if munging_opts.reply_goes_to_list then
-- Reply-to goes to the list
nreply = via_addr
end
if task:has_header('Reply-To') then
-- If we have reply-to header, then we need to insert an additional
-- address there
local orig_reply = task:get_header_full('Reply-To')[1]
if orig_reply.value then
nreply = string.format('%s, %s', orig_reply.value, nreply)
end
remove_hdrs['Reply-To'] = 1
end
add_hdrs['Reply-To'] = { order = 0, value = nreply }
add_hdrs['X-Original-From'] = { order = 0, value = orig_from_encoded }
lua_mime.modify_headers(task, {
remove = remove_hdrs,
add = add_hdrs
})
lua_util.debugm(N, task, 'munged DMARC header for %s: %s -> %s',
from.domain, hdr_encoded, from.addr)
rspamd_logger.infox(task, 'munged DMARC header for %s', from.addr)
task:insert_result('DMARC_MUNGED', 1.0, from.addr)
end
end
local function gen_dmarc_grammar()
local lpeg = require "lpeg"
lpeg.locale(lpeg)
local space = lpeg.space ^ 0
local name = lpeg.C(lpeg.alpha ^ 1) * space
local sep = space * (lpeg.S("\\;") * space) + (lpeg.P(lpeg.graph - lpeg.P(',')) * lpeg.space ^ 1)
local value = lpeg.C(lpeg.P(lpeg.P(lpeg.graph + lpeg.space) - sep) ^ 1)
local pair = lpeg.Cg(name * "=" * space * value) * sep ^ -1
local list = lpeg.Cf(lpeg.Ct("") * pair ^ 0, rawset)
local version = lpeg.P("v") * space * lpeg.P("=") * space * lpeg.P("DMARC1")
local record = version * sep * list
return record
end
local dmarc_grammar = gen_dmarc_grammar()
local function dmarc_key_value_case(elts)
if type(elts) ~= "table" then
return elts
end
local result = {}
for k, v in pairs(elts) do
k = k:lower()
if k ~= "v" then
v = v:lower()
end
result[k] = v
end
return result
end
--[[
-- Used to check dmarc record, check elements and produce dmarc policy processed
-- result.
-- Returns:
-- false,false - record is garbage
-- false,error_message - record is invalid
-- true,policy_table - record is valid and parsed
]]
local function dmarc_check_record(log_obj, record, is_tld)
local failed_policy
local result = {
dmarc_policy = 'none'
}
local elts = dmarc_grammar:match(record)
lua_util.debugm(N, log_obj, "got DMARC record: %s, tld_flag=%s, processed=%s",
record, is_tld, elts)
if elts then
elts = dmarc_key_value_case(elts)
local dkim_pol = elts['adkim']
if dkim_pol then
if dkim_pol == 's' then
result.strict_dkim = true
elseif dkim_pol ~= 'r' then
failed_policy = 'adkim tag has invalid value: ' .. dkim_pol
return false, failed_policy
end
end
local spf_pol = elts['aspf']
if spf_pol then
if spf_pol == 's' then
result.strict_spf = true
elseif spf_pol ~= 'r' then
failed_policy = 'aspf tag has invalid value: ' .. spf_pol
return false, failed_policy
end
end
local policy = elts['p']
if policy then
if (policy == 'reject') then
result.dmarc_policy = 'reject'
elseif (policy == 'quarantine') then
result.dmarc_policy = 'quarantine'
elseif (policy ~= 'none') then
failed_policy = 'p tag has invalid value: ' .. policy
return false, failed_policy
end
end
-- Adjust policy if we are in tld mode
local subdomain_policy = elts['sp']
if elts['sp'] and is_tld then
result.subdomain_policy = elts['sp']
if (subdomain_policy == 'reject') then
result.dmarc_policy = 'reject'
elseif (subdomain_policy == 'quarantine') then
result.dmarc_policy = 'quarantine'
elseif (subdomain_policy == 'none') then
result.dmarc_policy = 'none'
elseif (subdomain_policy ~= 'none') then
failed_policy = 'sp tag has invalid value: ' .. subdomain_policy
return false, failed_policy
end
end
result.pct = elts['pct']
if result.pct then
result.pct = tonumber(result.pct)
end
if elts.rua then
result.rua = elts['rua']
end
result.raw_elts = elts
else
return false, false -- Ignore garbage
end
return true, result
end
exports.dmarc_check_record = dmarc_check_record
return exports
|