Adding upstream version 5.6.0.upstream/5.6.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 532 insertions, 0 deletions

diff --git a/daemon/lua/trust_anchors.lua.in b/daemon/lua/trust_anchors.lua.in
new file mode 100644
index 0000000..56a7f95
--- /dev/null
+++ b/daemon/lua/trust_anchors.lua.in
@@ -0,0 +1,532 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+
+-- Load the module
+local ffi = require 'ffi'
+local kres = require('kres')
+local C = ffi.C
+
+local trust_anchors -- the public pseudo-module, exported as global variable
+
+-- RFC5011 state table
+local key_state = {
+	Start = 'Start', AddPend = 'AddPend', Valid = 'Valid',
+	Missing = 'Missing', Revoked = 'Revoked', Removed = 'Removed'
+}
+
+local function upgrade_required(msg)
+	if msg then
+		msg = msg .. '\n'
+	else
+		msg = ''
+	end
+	panic('Configuration upgrade required: ' .. msg .. 'Please refer to ' ..
+		'https://knot-resolver.readthedocs.io/en/stable/upgrading.html')
+end
+
+-- TODO: Move bootstrap to a separate module or even its own binary
+-- remove UTC timezone specification if present or throw error
+local function time2utc(orig_timespec)
+	local patterns = {'[+-]00:00$', 'Z$'}
+	for _, pattern in ipairs(patterns) do
+		local timespec, removals = string.gsub(orig_timespec, pattern, '')
+		if removals == 1 then
+			return timespec
+		end
+	end
+	error(string.format('unsupported time specification: %s', orig_timespec))
+end
+
+local function keydigest_is_valid(valid_from, valid_until)
+	local format =            '%Y-%m-%dT%H:%M:%S'
+	local time_now = os.date('!%Y-%m-%dT%H:%M:%S')  -- ! forces UTC
+	local time_diff = ffi.new('double[1]')
+	local err = ffi.C.kr_strptime_diff(
+		format, time_now, time2utc(valid_from), time_diff)
+	if (err ~= nil) then
+		error(string.format('failed to process "validFrom" constraint: %s',
+			ffi.string(err)))
+	end
+	local from_ok = time_diff[0] > 0
+
+	-- optional attribute
+	local until_ok = true
+	if valid_until then
+		err = ffi.C.kr_strptime_diff(
+			format, time_now, time2utc(valid_until), time_diff)
+		if (err ~= nil) then
+			error(string.format('failed to process "validUntil" constraint: %s',
+				ffi.string(err)))
+		end
+		until_ok = time_diff[0] < 0
+	end
+	return from_ok and until_ok
+end
+
+local function parse_xml_keydigest(attrs, inside, output)
+	local fields = {}
+	local _, n = string.gsub(attrs, "([%w]+)=\"([^\"]*)\"", function (k, v) fields[k] = v end)
+	assert(n >= 1,
+		string.format('cannot parse XML attributes from "%s"', attrs))
+	assert(fields['validFrom'],
+		string.format('mandatory KeyDigest XML attribute validFrom ' ..
+		'not found in "%s"', attrs))
+	local valid_attrs = {id = true, validFrom = true, validUntil = true}
+	for key, _ in pairs(fields) do
+		assert(valid_attrs[key],
+			string.format('unsupported KeyDigest attribute "%s" found in "%s"',
+				key, attrs))
+	end
+
+	_, n = string.gsub(inside, "<([%w]+).->([^<]+)</[%w]+>", function (k, v) fields[k] = v end)
+	assert(n >= 1,
+		string.format('error parsing KeyDigest XML elements from "%s"',
+			inside))
+	local mandatory_elements = {'KeyTag', 'Algorithm', 'DigestType', 'Digest'}
+	for _, key in ipairs(mandatory_elements) do
+		assert(fields[key],
+			string.format('mandatory element %s is missing in "%s"',
+				key, inside))
+	end
+	assert(n == 4, string.format('found %d elements but expected 4 in %s', n, inside))
+	table.insert(output, fields)  -- append to list of parsed keydigests
+end
+
+local function generate_ds(keydigests)
+	local rrset = ''
+	for _, fields in ipairs(keydigests) do
+		local rr = string.format(
+			'. 0 IN DS %s %s %s %s',
+			fields.KeyTag, fields.Algorithm, fields.DigestType, fields.Digest)
+		if keydigest_is_valid(fields['validFrom'], fields['validUntil']) then
+			rrset = rrset .. '\n' .. rr
+		else
+			log_info(ffi.C.LOG_GRP_TA, 'skipping trust anchor "%s" ' ..
+				'because it is outside of validity range', rr)
+		end
+	end
+	return rrset
+end
+
+local function assert_str_match(str, pattern, expected)
+	local count = 0
+	for _ in string.gmatch(str, pattern) do
+		count = count + 1
+	end
+	assert(count == expected,
+		string.format('expected %d occurences of "%s" but got %d in "%s"',
+			expected, pattern, count, str))
+end
+
+-- Fetch root anchors in XML over HTTPS, returning a zone-file-style string
+-- or false in case of error, and a message.
+local function bootstrap(url, ca)
+	local kluautil = require('kluautil')
+	local file = io.tmpfile()
+	-- RFC 7958, sec. 2, but we don't do precise XML parsing.
+	-- @todo ICANN certificate is verified against current CA
+	--       this is not ideal, as it should rather verify .xml signature which
+	--       is signed by ICANN long-lived cert, but luasec has no PKCS7
+	local rcode, errmsg = kluautil.kr_https_fetch(url, file, ca)
+	if rcode == nil then
+		file:close()
+		return false, string.format('[ ta ] fetch of "%s" failed: %s', url, errmsg)
+	end
+
+	local xml = file:read("*a")
+	file:close()
+
+	-- we support only minimal subset of https://tools.ietf.org/html/rfc7958
+	assert_str_match(xml, '<?xml version="1%.0" encoding="UTF%-8"%?>', 1)
+	assert_str_match(xml, '<TrustAnchor ', 1)
+	assert_str_match(xml, '<Zone>.</Zone>', 1)
+	assert_str_match(xml, '</TrustAnchor>', 1)
+
+	-- Parse root trust anchor, one digest at a time, converting to a zone-file-style string.
+	local keydigests = {}
+	string.gsub(xml, "<KeyDigest([^>]*)>(.-)</KeyDigest>", function(attrs, inside)
+		parse_xml_keydigest(attrs, inside, keydigests)
+	end)
+	local rrset = generate_ds(keydigests)
+	if rrset == '' then
+		return false, string.format('[ ta ] no valid trust anchors found at "%s"', url)
+	end
+	local msg = '[ ta ] Root trust anchors bootstrapped over https with pinned certificate.\n'
+			.. '       You SHOULD verify them manually against original source:\n'
+			.. '       https://www.iana.org/dnssec/files\n'
+			.. '[ ta ] Bootstrapped root trust anchors are:'
+			.. rrset
+	return rrset, msg
+end
+
+local function bootstrap_write(rrstr, filename)
+	local fname_tmp = filename .. '.lock.' .. tostring(worker.pid);
+	local file = assert(io.open(fname_tmp, 'w'))
+	file:write(rrstr)
+	file:close()
+	assert(os.rename(fname_tmp, filename))
+end
+-- Bootstrap end
+
+-- Update ta.comment and return decorated line representing the RR
+-- This is meant to be in zone-file format.
+local function ta_rr_str(ta)
+	ta.comment = ' ' .. ta.state .. ':' .. (ta.timer or '')
+				.. ' ; KeyTag:' .. ta.key_tag -- the tag is just for humans
+	local rr_str = kres.rr2str(ta) .. '\n'
+	if ta.state ~= key_state.Valid and ta.state ~= key_state.Missing then
+		rr_str = '; '..rr_str -- Invalidate key string (for older kresd versions)
+	end
+	return rr_str
+end
+
+-- Write keyset to a file.  States and timers are stored in comments.
+local function keyset_write(keyset)
+	if not keyset.managed then  -- not to be persistent, this is an error!
+		panic('internal error: keyset_write called for an unmanaged TA')
+	end
+	local fname_tmp = keyset.filename .. '.lock.' .. tostring(worker.pid);
+	local file = assert(io.open(fname_tmp, 'w'))
+	for i = 1, #keyset do
+		file:write(ta_rr_str(keyset[i]))
+	end
+	file:close()
+	assert(os.rename(fname_tmp, keyset.filename))
+end
+
+-- Search the values of a table and return the corresponding key (or nil).
+local function table_search(t, val)
+	for k, v in pairs(t) do
+		if v == val then
+			return k
+		end
+	end
+	return nil
+end
+
+-- For each RR, parse .state and .timer from .comment.
+local function keyset_parse_comments(tas, default_state)
+	for _, ta in pairs(tas) do
+		ta.state = default_state
+		if ta.comment then
+			string.gsub(ta.comment, '^%s*(%a+):(%d*)', function (state, time)
+				if table_search(key_state, state) then
+					ta.state = state
+				end
+				ta.timer = tonumber(time) -- nil on failure
+			end)
+			ta.comment = nil
+		end
+	end
+	return tas
+end
+
+-- Read keyset from a file xor a string.  (This includes the key states and timers.)
+local function keyset_read(path, str)
+	if (path == nil) == (str == nil) then -- exactly one of them must be nil
+		return nil, "internal ERROR: incorrect call to TA's keyset_read"
+	end
+	-- First load the regular entries, trusting them.
+	local zonefile = require('zonefile')
+	local tas, err
+	if path ~= nil then
+		tas, err = zonefile.file(path)
+	else
+		tas, err = zonefile.string(str)
+	end
+	if not tas then
+		return tas, err
+	end
+	keyset_parse_comments(tas, key_state.Valid)
+
+	-- The untrusted keys are commented out but important to load.
+	local line_iter
+	if path ~= nil then
+		line_iter = io.lines(path)
+	else
+		line_iter = string.gmatch(str, "[^\n]+")
+	end
+	for line in line_iter do
+		if line:sub(1, 2) == '; ' then
+			-- Ignore the line if it fails to parse including recognized .state.
+			local l_set = zonefile.string(line:sub(3))
+			if l_set and l_set[1] then
+				keyset_parse_comments(l_set)
+				if l_set[1].state then
+					table.insert(tas, l_set[1])
+				end
+			end
+		end
+	end
+
+	-- Fill tas[*].key_tag
+	for _, ta in pairs(tas) do
+		local ta_keytag = C.kr_dnssec_key_tag(ta.type, ta.rdata, #ta.rdata)
+		if not (ta_keytag >= 0 and ta_keytag <= 65535) then
+			return nil, string.format('invalid key: "%s": %s',
+				kres.rr2str(ta), ffi.string(C.knot_strerror(ta_keytag)))
+		end
+		ta.key_tag = ta_keytag
+	end
+
+	-- Fill tas.owner
+	if not tas[1] then
+		return nil, "empty TA set"
+	end
+	local owner = tas[1].owner
+	for _, ta in ipairs(tas) do
+		if ta.owner ~= owner then
+			return nil, string.format("do not mix %s and %s TAs in single file/string",
+				kres.dname2str(ta.owner), kres.dname2str(owner))
+		end
+	end
+	tas.owner = owner
+
+	return tas
+end
+
+-- Replace current TAs for given owner by the "trusted" ones from passed keyset.
+-- Return true iff no TA errored out and at least one is in VALID state.
+local function keyset_publish(keyset)
+	local store = kres.context().trust_anchors
+	local count = 0
+	local has_error = false
+	C.kr_ta_del(store, keyset.owner)
+	for _, ta in ipairs(keyset) do
+		-- Key MAY be used as a TA only in these two states (RFC5011, 4.2)
+		if ta.state == key_state.Valid or ta.state == key_state.Missing then
+			if C.kr_ta_add(store, ta.owner, ta.type, ta.ttl, ta.rdata, #ta.rdata) == 0 then
+				count = count + 1
+			else
+				ta.state = 'ERROR'
+				has_error = true
+			end
+		end
+	end
+	if count == 0 then
+		log_error(ffi.C.LOG_GRP_TA, 'ERROR: no anchors are trusted for ' ..
+			kres.dname2str(keyset.owner) .. ' !')
+	end
+	return count > 0 and not has_error
+end
+
+local function add_file(path, unmanaged)
+	local managed = not unmanaged
+	if not ta_update then
+		modules.load('ta_update')
+	end
+	if managed then
+		if not io.open(path .. '.lock', 'w') then
+			error("[ ta ] ERROR: write access needed to keyfile dir '"..path.."'")
+		end
+		os.remove(path .. ".lock")
+	end
+
+	-- Bootstrap TA for root zone if keyfile doesn't exist
+	if managed and not io.open(path, 'r') then
+		if trust_anchors.keysets['\0'] then
+			error(string.format(
+				"[ ta ] keyfile '%s' doesn't exist and root key is already installed, "
+				.. "cannot bootstrap; provide a path to valid file with keys", path))
+		end
+		log_info(ffi.C.LOG_GRP_TA, "keyfile '%s': doesn't exist, bootstrapping", path);
+		local rrstr, msg = bootstrap(trust_anchors.bootstrap_url, trust_anchors.bootstrap_ca)
+		if not rrstr then
+			msg = msg .. '\n'
+				.. '[ ta ] Failed to bootstrap root trust anchors!'
+			error(msg)
+		end
+		print(msg)
+		bootstrap_write(rrstr, path)
+		-- continue as if the keyfile was there
+	end
+
+	-- Parse the file and check its sanity
+	local keyset, err = keyset_read(path)
+	if not keyset then
+		panic("[ ta ] ERROR: failed to read anchors from '%s' (%s)", path, err)
+	end
+	keyset.filename = path
+	keyset.managed = managed
+
+	local owner = keyset.owner
+	local owner_str = kres.dname2str(owner)
+	local keyset_orig = trust_anchors.keysets[owner]
+	if keyset_orig then
+		log_warn(ffi.C.LOG_GRP_TA, 'warning: overriding previously set trust anchors for ' .. owner_str)
+		if keyset_orig.managed and ta_update then
+			ta_update.stop(owner)
+		end
+	end
+	trust_anchors.keysets[owner] = keyset
+
+	-- Replace the TA store used for validation
+	if keyset_publish(keyset) then
+		log_info(ffi.C.LOG_GRP_TA, 'installed trust anchors for domain ' .. owner_str .. ' are:\n'
+			.. trust_anchors.summary(owner))
+	end
+	-- TODO: if failed and for root, try to rebootstrap?
+
+	ta_update.start(owner, managed)
+end
+
+local function remove(zname)
+	local owner = kres.str2dname(zname)
+	if not trust_anchors.keysets[owner] then
+		return false
+	end
+
+	if ta_update then
+		ta_update.stop(owner)
+	end
+	trust_anchors.keysets[owner] = nil
+	local store = kres.context().trust_anchors
+	C.kr_ta_del(store, owner)
+	return true
+end
+
+local function ta_str(owner)
+	local owner_str = kres.dname2str(owner) .. ' '
+	local msg = ''
+	for _, nta in pairs(trust_anchors.insecure) do
+		if owner == kres.str2dname(nta) then
+			msg = owner_str .. 'is negative trust anchor\n'
+		end
+	end
+	if not trust_anchors.keysets[owner] then
+		if #msg > 0 then  -- it is normal that NTA does not have explicit TA
+			return msg
+		else
+			return owner_str .. 'has no explicit trust anchors\n'
+		end
+	end
+	if #msg > 0 then
+		msg = msg .. 'WARNING! negative trust anchor also has an explicit TA\n'
+	end
+	for _, ta in ipairs(trust_anchors.keysets[owner]) do
+		msg = msg .. ta_rr_str(ta)
+	end
+	return msg
+end
+
+-- TA store management, for user docs see ../README.rst
+trust_anchors = {
+	-- [internal] table indexed by dname;
+	--  each item is a list of RRs and additionally contains:
+	--   - owner - that dname (for simplicity)
+	--   - [optional] filename in which to persist the state,
+	--     implying unmanaged TA if nil
+	-- The RR tables also contain some additional TA-specific fields.
+	keysets = {},
+
+	-- Documented properties:
+	insecure = {},
+
+	bootstrap_url = 'https://data.iana.org/root-anchors/root-anchors.xml',
+	bootstrap_ca = '@etc_dir@/icann-ca.pem',
+
+	-- Load keys from a file, 5011-managed by default.
+	-- If managed and the file doesn't exist, try bootstrapping the root into it.
+	add_file = add_file,
+	config = function() upgrade_required('trust_anchors.config was removed, use trust_anchors.add_file()') end,
+	remove = remove,
+
+	keyset_publish = keyset_publish,
+	keyset_write = keyset_write,
+	key_state = key_state,
+
+	-- Add DS/DNSKEY record(s) (unmanaged)
+	add = function (keystr)
+		local keyset, err = keyset_read(nil, keystr)
+		if keyset ~= nil then
+			local owner = keyset.owner
+			local owner_str = kres.dname2str(owner)
+			local keyset_orig = trust_anchors.keysets[owner]
+			-- Set up trust_anchors.keysets[owner]
+			if keyset_orig then
+				if keyset_orig.managed then
+					panic('[ ta ] it is impossible to add an unmanaged TA for zone '
+						.. owner_str .. ' which already has a managed TA')
+				end
+				log_warn(ffi.C.LOG_GRP_TA, 'warning: extending previously set trust anchors for '
+						.. owner_str)
+				for _, ta in ipairs(keyset) do
+					table.insert(keyset_orig, ta)
+				end
+			end
+			-- Replace the TA store used for validation
+			if not keyset_publish(keyset) then
+				err = "when publishing the TA set"
+				-- trust_anchors.keysets[owner] was already updated to the
+				-- (partially) failing state, but I'm not sure how much to improve this
+			end
+			keyset.managed = false
+			trust_anchors.keysets[owner] = keyset
+
+		end
+		log_info(ffi.C.LOG_GRP_TA, 'New TA state:\n' .. trust_anchors.summary())
+		if err then
+			panic('[ ta ] .add() failed: ' .. err)
+		end
+	end,
+
+	-- Negative TA management
+	set_insecure = function (list)
+		assert(type(list) == 'table', 'parameter must be list of domain names (e.g. {"a.test", "b.example"})')
+		local store = kres.context().negative_anchors
+		for i = 1, #list do
+			local dname = kres.str2dname(list[i])
+			if trust_anchors.keysets[dname] then
+				error('cannot add NTA '..list[i]..' because it is TA. Use trust_anchors.remove() instead')
+			end
+		end
+
+		C.kr_ta_clear(store)
+		for i = 1, #list do
+			local dname = kres.str2dname(list[i])
+			C.kr_ta_add(store, dname, kres.type.DS, 0, nil, 0)
+		end
+		trust_anchors.insecure = list
+	end,
+	-- Return textual representation of all TAs (incl. negative)
+	-- It's meant for human consumption.
+	summary = function (single_owner)
+		if single_owner then  -- single domain
+			return ta_str(single_owner)
+		end
+
+		-- all domains
+		local msg = ''
+		local ta_count = 0
+		local seen = {}
+		for _, nta_str in pairs(trust_anchors.insecure) do
+			local owner = kres.str2dname(nta_str)
+			seen[owner] = true
+			msg = msg .. ta_str(owner)
+		end
+		for owner, _ in pairs(trust_anchors.keysets) do
+			if not seen[owner] then
+				ta_count = ta_count + 1
+				msg = msg .. ta_str(owner)
+			end
+		end
+		if ta_count == 0 then
+			msg = msg .. 'No valid trust anchors, DNSSEC validation is disabled\n'
+		end
+		return msg
+	end,
+}
+
+-- Syntactic sugar for TA store
+setmetatable(trust_anchors, {
+       __newindex = function (t,k,v)
+       if     k == 'file' then
+	       upgrade_required('trust_anchors.file was removed, use trust_anchors.add_file()')
+       elseif k == 'negative' then
+	       upgrade_required('trust_anchors.negative was removed, use trust_anchors.set_insecure()')
+       elseif k == 'keyfile_default' then
+	       upgrade_required('trust_anchors.keyfile_default is now compiled in, see trust_anchors.remove()')
+       else   rawset(t, k, v) end
+       end,
+})
+
+return trust_anchors