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--[[
Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com>
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.
]]--
--[[[
-- @module clamav
-- This module contains clamav access functions
--]]
local lua_util = require "lua_util"
local tcp = require "rspamd_tcp"
local upstream_list = require "rspamd_upstream_list"
local rspamd_util = require "rspamd_util"
local rspamd_logger = require "rspamd_logger"
local common = require "lua_scanners/common"
local N = "clamav"
local default_message = '${SCANNER}: virus found: "${VIRUS}"'
local function clamav_config(opts)
local clamav_conf = {
name = N,
scan_mime_parts = true,
scan_text_mime = false,
scan_image_mime = false,
default_port = 3310,
log_clean = false,
timeout = 5.0, -- FIXME: this will break task_timeout!
detection_category = "virus",
retransmits = 2,
cache_expire = 3600, -- expire redis in one hour
message = default_message,
}
clamav_conf = lua_util.override_defaults(clamav_conf, opts)
if not clamav_conf.prefix then
clamav_conf.prefix = 'rs_' .. clamav_conf.name .. '_'
end
if not clamav_conf.log_prefix then
if clamav_conf.name:lower() == clamav_conf.type:lower() then
clamav_conf.log_prefix = clamav_conf.name
else
clamav_conf.log_prefix = clamav_conf.name .. ' (' .. clamav_conf.type .. ')'
end
end
if not clamav_conf['servers'] then
rspamd_logger.errx(rspamd_config, 'no servers defined')
return nil
end
clamav_conf['upstreams'] = upstream_list.create(rspamd_config,
clamav_conf['servers'],
clamav_conf.default_port)
if clamav_conf['upstreams'] then
lua_util.add_debug_alias('antivirus', clamav_conf.name)
return clamav_conf
end
rspamd_logger.errx(rspamd_config, 'cannot parse servers %s',
clamav_conf['servers'])
return nil
end
local function clamav_check(task, content, digest, rule, maybe_part)
local function clamav_check_uncached ()
local upstream = rule.upstreams:get_upstream_round_robin()
local addr = upstream:get_addr()
local retransmits = rule.retransmits
local header = rspamd_util.pack("c9 c1 >I4", "zINSTREAM", "\0",
#content)
local footer = rspamd_util.pack(">I4", 0)
local function clamav_callback(err, data)
if err then
-- retry with another upstream until retransmits exceeds
if retransmits > 0 then
retransmits = retransmits - 1
-- Select a different upstream!
upstream = rule.upstreams:get_upstream_round_robin()
addr = upstream:get_addr()
lua_util.debugm(rule.name, task, '%s: error: %s; retry IP: %s; retries left: %s',
rule.log_prefix, err, addr, retransmits)
tcp.request({
task = task,
host = addr:to_string(),
port = addr:get_port(),
upstream = upstream,
timeout = rule['timeout'],
callback = clamav_callback,
data = { header, content, footer },
stop_pattern = '\0'
})
else
rspamd_logger.errx(task, '%s: failed to scan, maximum retransmits exceed', rule.log_prefix)
common.yield_result(task, rule,
'failed to scan and retransmits exceed', 0.0, 'fail',
maybe_part)
end
else
data = tostring(data)
local cached
lua_util.debugm(rule.name, task, '%s: got reply: %s',
rule.log_prefix, data)
if data == 'stream: OK' then
cached = 'OK'
if rule['log_clean'] then
rspamd_logger.infox(task, '%s: message or mime_part is clean',
rule.log_prefix)
else
lua_util.debugm(rule.name, task, '%s: message or mime_part is clean', rule.log_prefix)
end
else
local vname = string.match(data, 'stream: (.+) FOUND')
if string.find(vname, '^Heuristics%.Encrypted') then
rspamd_logger.errx(task, '%s: File is encrypted', rule.log_prefix)
common.yield_result(task, rule, 'File is encrypted: ' .. vname,
0.0, 'encrypted', maybe_part)
cached = 'ENCRYPTED'
elseif string.find(vname, '^Heuristics%.OLE2%.ContainsMacros') then
rspamd_logger.errx(task, '%s: ClamAV Found an OLE2 Office Macro', rule.log_prefix)
common.yield_result(task, rule, vname, 0.0, 'macro', maybe_part)
cached = 'MACRO'
elseif string.find(vname, '^Heuristics%.Limits%.Exceeded') then
rspamd_logger.errx(task, '%s: ClamAV Limits Exceeded', rule.log_prefix)
common.yield_result(task, rule, 'Limits Exceeded: ' .. vname, 0.0,
'fail', maybe_part)
elseif vname then
common.yield_result(task, rule, vname, 1.0, nil, maybe_part)
cached = vname
else
rspamd_logger.errx(task, '%s: unhandled response: %s', rule.log_prefix, data)
common.yield_result(task, rule, 'unhandled response:' .. vname, 0.0,
'fail', maybe_part)
end
end
if cached then
common.save_cache(task, digest, rule, cached, 1.0, maybe_part)
end
end
end
tcp.request({
task = task,
host = addr:to_string(),
port = addr:get_port(),
timeout = rule['timeout'],
callback = clamav_callback,
upstream = upstream,
data = { header, content, footer },
stop_pattern = '\0'
})
end
if common.condition_check_and_continue(task, content, rule, digest,
clamav_check_uncached, maybe_part) then
return
else
clamav_check_uncached()
end
end
return {
type = 'antivirus',
description = 'clamav antivirus',
configure = clamav_config,
check = clamav_check,
name = N
}
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