From 3d33e52838478edc372d80a52186e5b55c8b730c Mon Sep 17 00:00:00 2001 From: Arseny Smirnov Date: Tue, 25 Jun 2019 23:06:27 +0200 Subject: [PATCH] TlsObfuscation: TlsInit actor draft GitOrigin-RevId: 71f79ac151ee71d825c94733345d442a68e57496 --- test/mtproto.cpp | 445 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 445 insertions(+) diff --git a/test/mtproto.cpp b/test/mtproto.cpp index dd958f27..3b726b86 100644 --- a/test/mtproto.cpp +++ b/test/mtproto.cpp @@ -29,12 +29,15 @@ #include "td/telegram/net/Session.h" #include "td/telegram/NotificationManager.h" +#include "td/utils/as.h" #include "td/utils/base64.h" #include "td/utils/common.h" +#include "td/utils/crypto.h" #include "td/utils/logging.h" #include "td/utils/port/IPAddress.h" #include "td/utils/port/SocketFd.h" #include "td/utils/Random.h" +#include "td/utils/Span.h" #include "td/utils/Status.h" #include "td/utils/Time.h" @@ -586,3 +589,445 @@ class Mtproto_FastPing : public Test { Status result_; }; RegisterTest mtproto_fastping("Mtproto_FastPing"); + +class Grease { + public: + static void init(MutableSlice res) { + Random::secure_bytes(res); + for (auto &c : res) { + c = (c & 0xF0) + 0x0A; + } + for (size_t i = 1; i < res.size(); i += 2) { + if (res[i] == res[i - 1]) { + res[i] ^= 0x10; + } + } + } +}; + +class TlsHello { + public: + struct Op { + enum class Type { String, Random, Zero, Domain, Grease, BeginScope, EndScope }; + Type type; + int length; + int seed; + std::string data; + + static Op string(Slice str) { + Op res; + res.type = Type::String; + res.data = str.str(); + return res; + } + static Op random(int length) { + Op res; + res.type = Type::Random; + res.length = length; + return res; + } + static Op zero(int length) { + Op res; + res.type = Type::Zero; + res.length = length; + return res; + } + static Op domain() { + Op res; + res.type = Type::Domain; + return res; + } + static Op grease(int seed) { + Op res; + res.type = Type::Grease; + res.seed = seed; + return res; + } + static Op begin_scope() { + Op res; + res.type = Type::BeginScope; + return res; + } + static Op end_scope() { + Op res; + res.type = Type::EndScope; + return res; + } + }; + + static const TlsHello &get_default() { + static TlsHello res = [] { + TlsHello res; + res.ops_ = { + Op::string("\x16\x03\x01\x02\x00\x01\x00\x01\xfc\x03\x03"), + Op::zero(32), + Op::string("\x20"), + Op::random(32), + Op::string("\x00\x22"), + Op::grease(0), + Op::string("\x13\x01\x13\x02\x13\x03\xc0\x2b\xc0\x2f\xc0\x2c\xc0\x30\xcc\xa9\xcc\xa8\xc0\x13\xc0\x14\x00\x9c" + "\x00\x9d\x00\x2f\x00\x35\x00\x0a\x01\x00\x01\x91"), + Op::grease(2), + Op::string("\x00\x00\x00\x00"), + Op::begin_scope(), + Op::begin_scope(), + Op::string("\x00"), + Op::begin_scope(), + Op::domain(), + Op::end_scope(), + Op::end_scope(), + Op::end_scope(), + Op::string("\x00\x17\x00\x00\xff\x01\x00\x01\x00\x00\x0a\x00\x0a\x00\x08"), + Op::grease(4), + Op::string( + "\x00\x1d\x00\x17\x00\x18\x00\x0b\x00\x02\x01\x00\x00\x23\x00\x00\x00\x10\x00\x0e\x00\x0c\x02\x68\x32\x08" + "\x68\x74\x74\x70\x2f\x31\x2e\x31\x00\x05\x00\x05\x01\x00\x00\x00\x00\x00\x0d\x00\x14\x00\x12\x04\x03\x08" + "\x04\x04\x01\x05\x03\x08\x05\x05\x01\x08\x06\x06\x01\x02\x01\x00\x12\x00\x00\x00\x33\x00\x2b\x00\x29"), + Op::grease(4), + Op::string("\x00\x01\x00\x00\x1d\x00\x20"), + Op::random(32), + Op::string("\x00\x2d\x00\x02\x01\x01\x00\x2b\x00\x0b\x0a"), + Op::grease(6), + Op::string("\x03\x04\x03\x03\x03\x02\x03\x01\x00\x1b\x00\x03\x02\x00\x02"), + Op::grease(3), + Op::string("\x00\x01\x00\x00\x15")}; + return res; + }(); + return res; + } + Span get_ops() const { + return ops_; + } + + private: + std::vector ops_; +}; + +class TlsHelloContext { + public: + explicit TlsHelloContext(std::string domain) { + Grease::init(MutableSlice(grease_.data(), grease_.size())); + domain_ = std::move(domain); + } + char get_grease(size_t i) const { + CHECK(i < grease_.size()); + return grease_[i]; + } + size_t grease_size() const { + return grease_.size(); + } + Slice get_domain() const { + return domain_; + } + + private: + constexpr static size_t MAX_GREASE = 8; + std::array grease_; + std::string domain_; +}; + +class TlsHelloCalcLength { + public: + void do_op(const TlsHello::Op &op, const TlsHelloContext *context) { + using Type = TlsHello::Op::Type; + switch (op.type) { + case Type::String: + size_ += op.data.size(); + break; + case Type::Random: + if (op.length <= 0 || op.length > 1024) { + on_error(Status::Error("Invalid random length")); + } + size_ += op.length; + break; + case Type::Zero: + if (op.length < 0 || op.length > 1024) { + on_error(Status::Error("Invalid zero length")); + } + size_ += op.length; + break; + case Type::Domain: + CHECK(context); + size_ += context->get_domain().size(); + break; + case Type::Grease: + CHECK(context); + if (op.seed < 0 || static_cast(op.seed) > context->grease_size()) { + on_error(Status::Error("Invalid grease seed")); + } + size_ += 2; + break; + case Type::BeginScope: + size_ += 2; + scope_offset_.push_back(size_); + break; + case Type::EndScope: + if (scope_offset_.empty()) { + on_error(Status::Error("Unbalanced scopes")); + } + auto begin_offset = scope_offset_.back(); + scope_offset_.pop_back(); + auto end_offset = size_; + auto size = end_offset - begin_offset; + if (size >= (1 << 14)) { + on_error(Status::Error("Scope is too big")); + } + break; + } + } + + Result finish() { + if (size_ > 515) { + on_error(Status::Error("Too long for zero padding")); + } + if (size_ < 11 + 32) { + on_error(Status::Error("Too small for hash")); + } + int zero_pad = 515 - static_cast(size_); + using Op = TlsHello::Op; + do_op(Op::begin_scope(), nullptr); + do_op(Op::zero(zero_pad), nullptr); + do_op(Op::end_scope(), nullptr); + if (!scope_offset_.empty()) { + on_error(Status::Error("Unbalanced scopes")); + } + TRY_STATUS(std::move(status_)); + return size_; + } + + private: + int64 size_{0}; + Status status_; + std::vector scope_offset_; + + void on_error(Status error) { + if (status_.is_ok()) { + status_ = std::move(error); + } + } +}; + +class TlsHelloStore { + public: + TlsHelloStore(MutableSlice dest) : data_(dest), dest_(dest) { + } + void do_op(const TlsHello::Op &op, TlsHelloContext *context) { + using Type = TlsHello::Op::Type; + switch (op.type) { + case Type::String: + dest_.copy_from(op.data); + dest_.remove_prefix(op.data.size()); + break; + case Type::Random: + Random::secure_bytes(dest_.substr(0, op.length)); + dest_.remove_prefix(op.length); + break; + case Type::Zero: + std::memset(dest_.begin(), 0, op.length); + dest_.remove_prefix(op.length); + break; + case Type::Domain: { + CHECK(context); + auto domain = context->get_domain(); + dest_.copy_from(domain); + dest_.remove_prefix(domain.size()); + break; + } + case Type::Grease: { + CHECK(context) + auto grease = context->get_grease(op.seed); + dest_[0] = grease; + dest_[1] = grease; + dest_.remove_prefix(2); + break; + } + case Type::BeginScope: + scope_offset_.push_back(get_offset()); + dest_.remove_prefix(2); + break; + case Type::EndScope: { + CHECK(!scope_offset_.empty()); + auto begin_offset = scope_offset_.back(); + scope_offset_.pop_back(); + auto end_offset = get_offset(); + size_t size = end_offset - begin_offset - 2; + CHECK(size < (1 << 14)); + data_[begin_offset] = static_cast((size >> 8) & 0xff); + data_[begin_offset + 1] = static_cast(size & 0xff); + break; + } + } + } + void finish(int32 unix_time) { + int zero_pad = 515 - static_cast(get_offset()); + using Op = TlsHello::Op; + do_op(Op::begin_scope(), nullptr); + do_op(Op::zero(zero_pad), nullptr); + do_op(Op::end_scope(), nullptr); + + auto tmp = sha256(data_); + auto hash_dest = data_.substr(11); + hash_dest.copy_from(tmp); + int32 old = as(hash_dest.substr(28).data()); + as(hash_dest.substr(28).data()) = old ^ unix_time; + CHECK(dest_.empty()); + } + + private: + MutableSlice data_; + MutableSlice dest_; + std::vector scope_offset_; + size_t get_offset() { + return data_.size() - dest_.size(); + } +}; + +class TlsObfusaction { + public: + static std::string generate_header(std::string domain, int32 unix_time) { + auto &hello = TlsHello::get_default(); + TlsHelloContext context(domain); + TlsHelloCalcLength calc_length; + for (auto &op : hello.get_ops()) { + calc_length.do_op(op, &context); + } + auto length = calc_length.finish().move_as_ok(); + std::string data(length, 0); + TlsHelloStore storer(data); + for (auto &op : hello.get_ops()) { + storer.do_op(op, &context); + } + storer.finish(0); + return data; + } +}; + +class TlsInit : public TransparentProxy { + public: + using TransparentProxy::TransparentProxy; + + private: + enum class State { + SendHello, + WaitHelloResponse, + } state_ = State::SendHello; + + void send_hello() { + auto hello = TlsObfusaction::generate_header(username_, 0); + fd_.output_buffer().append(hello); + state_ = State::WaitHelloResponse; + } + + Status wait_hello_response() { + //[ + auto it = fd_.input_buffer().clone(); + //S "\x16\x03\x03" + { + Slice first = "\x16\x03\x03"; + std::string got_first(first.size(), 0); + if (it.size() < first.size()) { + return td::Status::OK(); + } + it.advance(first.size(), got_first); + if (first != got_first) { + return Status::Error("First part of response to hello is invalid"); + } + } + + //[ + { + if (it.size() < 2) { + return td::Status::OK(); + } + uint8 tmp[2]; + it.advance(2, MutableSlice(tmp, 2)); + size_t skip_size = (tmp[0] << 8) + tmp[1]; + if (it.size() < skip_size) { + return td::Status::OK(); + } + it.advance(skip_size); + } + + //S "\x14\x03\x03\x00\x01\x01\x17\x03\x03" + { + Slice first = "\x14\x03\x03\x00\x01\x01\x17\x03\x03"; + std::string got_first(first.size(), 0); + if (it.size() < first.size()) { + return td::Status::OK(); + } + it.advance(first.size(), got_first); + if (first != got_first) { + return Status::Error("Second part of response to hello is invalid"); + } + } + + //[ + { + if (it.size() < 2) { + return td::Status::OK(); + } + uint8 tmp[2]; + it.advance(2, MutableSlice(tmp, 2)); + size_t skip_size = (tmp[0] << 8) + tmp[1]; + if (it.size() < skip_size) { + return td::Status::OK(); + } + it.advance(skip_size); + } + fd_.input_buffer() = std::move(it); + + stop(); + return td::Status::OK(); + } + + Status loop_impl() override { + switch (state_) { + case State::SendHello: + send_hello(); + break; + case State::WaitHelloResponse: + TRY_STATUS(wait_hello_response()); + break; + } + return Status::OK(); + } +}; + +TEST(Mtproto, TlsObfusaction) { + std::string s(10000, 'a'); + Grease::init(s); + for (auto c : s) { + CHECK((c & 0xf) == 0xa); + } + for (size_t i = 1; i < s.size(); i += 2) { + CHECK(s[i] != s[i - 1]); + } + std::string domain = "www.google.com"; + SET_VERBOSITY_LEVEL(VERBOSITY_NAME(ERROR)); + ConcurrentScheduler sched; + int threads_n = 1; + sched.init(threads_n); + { + auto guard = sched.get_main_guard(); + class Callback : public TransparentProxy::Callback { + public: + void set_result(Result result) override { + result.ensure(); + Scheduler::instance()->finish(); + } + void on_connected() override { + } + }; + IPAddress ip_address; + ip_address.init_host_port(domain, 443).ensure(); + SocketFd fd = SocketFd::open(ip_address).move_as_ok(); + create_actor("TlsInit", std::move(fd), IPAddress(), domain, "", make_unique(), ActorShared<>()) + .release(); + } + + sched.start(); + while (sched.run_main(10)) { + // empty + } + sched.finish(); +}