Files
scylladb/auth/transitional.cc
Avi Kivity 0900a88884 Merge 'auth: move passwords::check call to alien thread' from Andrzej Jackowski
Analysis of customer stalls revealed that the function `detail::hash_with_salt` (invoked by `passwords::check`) often blocks the reactor. Internally, this function uses the external `crypt_r` function to compute password hashes, which is CPU-intensive.

This PR addresses the issue in two ways:
1) `sha-512` is now the only password hashing scheme for new passwords (it was already the common-case).
2) `passwords::check` is moved to a dedicated alien thread.

Regarding point 1: before this change, the following hashing schemes were supported by     `identify_best_supported_scheme()`: bcrypt_y, bcrypt_a, SHA-512, SHA-256, and MD5. The reason for this was that the `crypt_r` function used for password hashing comes from an external library (currently `libxcrypt`), and the supported hashing algorithms vary depending on the library in use. However:
- The bcrypt schemes never worked properly because their prefixes lack the required round count (e.g. `$2y$` instead of `$2y$05$`). Moreover, bcrypt is slower than SHA-512, so it  not good idea to fix or use it.
- SHA-256 and SHA-512 both belong to the SHA-2 family. Libraries that support one almost always support the other, so it’s very unlikely to find SHA-256 without SHA-512.
- MD5 is no longer considered secure for password hashing.

Regarding point 2: the `passwords::check` call now runs on a shared alien thread created at database startup. An `std::mutex` synchronizes that thread with the shards. In theory this could introduce a frequent lock contention, but in practice each shard handles only a few hundred new connections per second—even during storms. There is already `_conns_cpu_concurrency_semaphore` in `generic_server` limits the number of concurrent connection handlers.

Fixes https://github.com/scylladb/scylladb/issues/24524

Backport not needed, as it is a new feature.

Closes scylladb/scylladb#24924

* github.com:scylladb/scylladb:
  main: utils: add thread names to alien workers
  auth: move passwords::check call to alien thread
  test: wait for 3 clients with given username in test_service_level_api
  auth: refactor password checking in password_authenticator
  auth: make SHA-512 the only password hashing scheme for new passwords
  auth: whitespace change in identify_best_supported_scheme()
  auth: require scheme as parameter for `generate_salt`
  auth: check password hashing scheme support on authenticator start

(cherry picked from commit c762425ea7)
2025-09-07 13:38:33 +03:00

251 lines
8.6 KiB
C++

/*
* Copyright (C) 2017-present ScyllaDB
*
* Modified by ScyllaDB
*/
/*
* SPDX-License-Identifier: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
*/
#include "auth/authenticated_user.hh"
#include "auth/authenticator.hh"
#include "auth/authorizer.hh"
#include "auth/default_authorizer.hh"
#include "auth/password_authenticator.hh"
#include "auth/permission.hh"
#include "service/raft/raft_group0_client.hh"
#include "utils/class_registrator.hh"
namespace auth {
static const sstring PACKAGE_NAME("com.scylladb.auth.");
static const sstring& transitional_authenticator_name() {
static const sstring name = PACKAGE_NAME + "TransitionalAuthenticator";
return name;
}
static const sstring& transitional_authorizer_name() {
static const sstring name = PACKAGE_NAME + "TransitionalAuthorizer";
return name;
}
class transitional_authenticator : public authenticator {
std::unique_ptr<authenticator> _authenticator;
public:
static const sstring PASSWORD_AUTHENTICATOR_NAME;
transitional_authenticator(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm, utils::alien_worker& hashing_worker)
: transitional_authenticator(std::make_unique<password_authenticator>(qp, g0, mm, hashing_worker)) {
}
transitional_authenticator(std::unique_ptr<authenticator> a)
: _authenticator(std::move(a)) {
}
virtual future<> start() override {
return _authenticator->start();
}
virtual future<> stop() override {
return _authenticator->stop();
}
virtual std::string_view qualified_java_name() const override {
return transitional_authenticator_name();
}
virtual bool require_authentication() const override {
return true;
}
virtual authentication_option_set supported_options() const override {
return _authenticator->supported_options();
}
virtual authentication_option_set alterable_options() const override {
return _authenticator->alterable_options();
}
virtual future<authenticated_user> authenticate(const credentials_map& credentials) const override {
auto i = credentials.find(authenticator::USERNAME_KEY);
if ((i == credentials.end() || i->second.empty())
&& (!credentials.contains(PASSWORD_KEY) || credentials.at(PASSWORD_KEY).empty())) {
// return anon user
return make_ready_future<authenticated_user>(anonymous_user());
}
return make_ready_future().then([this, &credentials] {
return _authenticator->authenticate(credentials);
}).handle_exception([](auto ep) {
try {
std::rethrow_exception(ep);
} catch (exceptions::authentication_exception&) {
// return anon user
return make_ready_future<authenticated_user>(anonymous_user());
}
});
}
virtual future<> create(std::string_view role_name, const authentication_options& options, ::service::group0_batch& mc) override {
return _authenticator->create(role_name, options, mc);
}
virtual future<> alter(std::string_view role_name, const authentication_options& options, ::service::group0_batch& mc) override {
return _authenticator->alter(role_name, options, mc);
}
virtual future<> drop(std::string_view role_name, ::service::group0_batch& mc) override {
return _authenticator->drop(role_name, mc);
}
virtual future<custom_options> query_custom_options(std::string_view role_name) const override {
return _authenticator->query_custom_options(role_name);
}
virtual bool uses_password_hashes() const override {
return _authenticator->uses_password_hashes();
}
virtual future<std::optional<sstring>> get_password_hash(std::string_view role_name) const override {
return _authenticator->get_password_hash(role_name);
}
virtual const resource_set& protected_resources() const override {
return _authenticator->protected_resources();
}
virtual ::shared_ptr<sasl_challenge> new_sasl_challenge() const override {
class sasl_wrapper : public sasl_challenge {
public:
sasl_wrapper(::shared_ptr<sasl_challenge> sasl)
: _sasl(std::move(sasl)) {
}
virtual bytes evaluate_response(bytes_view client_response) override {
try {
return _sasl->evaluate_response(client_response);
} catch (exceptions::authentication_exception&) {
_complete = true;
return {};
}
}
virtual bool is_complete() const override {
return _complete || _sasl->is_complete();
}
virtual future<authenticated_user> get_authenticated_user() const override {
return futurize_invoke([this] {
return _sasl->get_authenticated_user().handle_exception([](auto ep) {
try {
std::rethrow_exception(ep);
} catch (exceptions::authentication_exception&) {
// return anon user
return make_ready_future<authenticated_user>(anonymous_user());
}
});
});
}
const sstring& get_username() const override {
return _sasl->get_username();
}
private:
::shared_ptr<sasl_challenge> _sasl;
bool _complete = false;
};
return ::make_shared<sasl_wrapper>(_authenticator->new_sasl_challenge());
}
virtual future<> ensure_superuser_is_created() const override {
return _authenticator->ensure_superuser_is_created();
}
};
class transitional_authorizer : public authorizer {
std::unique_ptr<authorizer> _authorizer;
public:
transitional_authorizer(cql3::query_processor& qp, ::service::raft_group0_client& g0, ::service::migration_manager& mm)
: transitional_authorizer(std::make_unique<default_authorizer>(qp, g0, mm)) {
}
transitional_authorizer(std::unique_ptr<authorizer> a)
: _authorizer(std::move(a)) {
}
~transitional_authorizer() {
}
virtual future<> start() override {
return _authorizer->start();
}
virtual future<> stop() override {
return _authorizer->stop();
}
virtual std::string_view qualified_java_name() const override {
return transitional_authorizer_name();
}
virtual future<permission_set> authorize(const role_or_anonymous&, const resource&) const override {
static const permission_set transitional_permissions =
permission_set::of<
permission::CREATE,
permission::ALTER,
permission::DROP,
permission::SELECT,
permission::MODIFY>();
return make_ready_future<permission_set>(transitional_permissions);
}
virtual future<> grant(std::string_view s, permission_set ps, const resource& r, ::service::group0_batch& mc) override {
return _authorizer->grant(s, std::move(ps), r, mc);
}
virtual future<> revoke(std::string_view s, permission_set ps, const resource& r, ::service::group0_batch& mc) override {
return _authorizer->revoke(s, std::move(ps), r, mc);
}
virtual future<std::vector<permission_details>> list_all() const override {
return _authorizer->list_all();
}
virtual future<> revoke_all(std::string_view s, ::service::group0_batch& mc) override {
return _authorizer->revoke_all(s, mc);
}
virtual future<> revoke_all(const resource& r, ::service::group0_batch& mc) override {
return _authorizer->revoke_all(r, mc);
}
virtual const resource_set& protected_resources() const override {
return _authorizer->protected_resources();
}
};
}
//
// To ensure correct initialization order, we unfortunately need to use string literals.
//
static const class_registrator<
auth::authenticator,
auth::transitional_authenticator,
cql3::query_processor&,
::service::raft_group0_client&,
::service::migration_manager&,
utils::alien_worker&> transitional_authenticator_reg(auth::PACKAGE_NAME + "TransitionalAuthenticator");
static const class_registrator<
auth::authorizer,
auth::transitional_authorizer,
cql3::query_processor&,
::service::raft_group0_client&,
::service::migration_manager&> transitional_authorizer_reg(auth::PACKAGE_NAME + "TransitionalAuthorizer");