330 lines
11 KiB
C++
330 lines
11 KiB
C++
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2022-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#include "pam_client_session.hh"
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#include <sstream>
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#include <maxbase/pam_utils.hh>
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#include <maxscale/event.hh>
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using maxscale::Buffer;
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using std::string;
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namespace
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{
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/**
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* @brief Read the client's password, store it to MySQL-session
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*
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* @param dcb Client DCB
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* @param buffer Buffer containing the password
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*
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* @return True on success, false if memory allocation failed
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*/
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bool store_client_password(DCB* dcb, GWBUF* buffer)
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{
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bool rval = false;
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uint8_t header[MYSQL_HEADER_LEN];
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if (gwbuf_copy_data(buffer, 0, MYSQL_HEADER_LEN, header) == MYSQL_HEADER_LEN)
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{
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size_t plen = gw_mysql_get_byte3(header);
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MYSQL_session* ses = (MYSQL_session*)dcb->data;
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ses->auth_token = (uint8_t*)MXS_CALLOC(plen, sizeof(uint8_t));
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if (ses->auth_token)
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{
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ses->auth_token_len = gwbuf_copy_data(buffer, MYSQL_HEADER_LEN, plen, ses->auth_token);
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rval = true;
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}
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}
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return rval;
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}
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/**
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* Helper callback for PamClientSession::get_pam_user_services(). See SQLite3
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* documentation for more information.
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*
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* @param data Application data
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* @param columns Number of columns, must be 1
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* @param column_vals Column values
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* @param column_names Column names
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* @return Always 0
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*/
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int user_services_cb(void* data, int columns, char** column_vals, char** column_names)
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{
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mxb_assert(columns == 1);
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PamClientSession::StringVector* results = static_cast<PamClientSession::StringVector*>(data);
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if (column_vals[0])
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{
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results->push_back(column_vals[0]);
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}
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else
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{
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// Empty is a valid value.
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results->push_back("");
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}
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return 0;
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}
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}
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PamClientSession::PamClientSession(sqlite3* dbhandle, const PamInstance& instance)
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: m_dbhandle(dbhandle)
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, m_instance(instance)
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{
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}
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PamClientSession::~PamClientSession()
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{
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sqlite3_close_v2(m_dbhandle);
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}
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PamClientSession* PamClientSession::create(const PamInstance& inst)
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{
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// This handle is only used from one thread, can define no_mutex.
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sqlite3* dbhandle = NULL;
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int db_flags = SQLITE_OPEN_READONLY | SQLITE_OPEN_SHAREDCACHE | SQLITE_OPEN_NOMUTEX
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| SQLITE_OPEN_URI;
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if (sqlite3_open_v2(inst.m_dbname.c_str(), &dbhandle, db_flags, NULL) == SQLITE_OK)
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{
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sqlite3_busy_timeout(dbhandle, 1000);
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}
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else
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{
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MXS_ERROR("Failed to open SQLite3 handle.");
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}
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PamClientSession* rval = NULL;
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if (!dbhandle || (rval = new(std::nothrow) PamClientSession(dbhandle, inst)) == NULL)
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{
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sqlite3_close_v2(dbhandle);
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}
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return rval;
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}
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/**
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* Check which PAM services the session user has access to.
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*
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* @param dcb Client DCB
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* @param session MySQL session
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* @param services_out Output for services
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*/
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void PamClientSession::get_pam_user_services(const DCB* dcb, const MYSQL_session* session,
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StringVector* services_out)
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{
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string services_query = string("SELECT authentication_string FROM ") + m_instance.m_tablename + " WHERE "
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+ FIELD_USER + " = '" + session->user + "'"
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+ " AND '" + dcb->remote + "' LIKE " + FIELD_HOST
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+ " AND (" + FIELD_ANYDB + " = '1' OR '" + session->db + "' = '' OR '"
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+ session->db + "' LIKE " + FIELD_DB + ")"
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+ " AND " + FIELD_PROXY + " = '0' ORDER BY authentication_string;";
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MXS_DEBUG("PAM services search sql: '%s'.", services_query.c_str());
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char* err;
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if (sqlite3_exec(m_dbhandle, services_query.c_str(), user_services_cb, services_out, &err) != SQLITE_OK)
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{
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MXS_ERROR("Failed to execute query: '%s'", err);
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sqlite3_free(err);
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}
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auto word_entry = [](size_t num) -> const char* {
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return (num == 1) ? "entry" : "entries";
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};
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if (!services_out->empty())
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{
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auto num_services = services_out->size();
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MXS_INFO("Found %lu valid PAM user %s for '%s'@'%s'.",
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num_services, word_entry(num_services), session->user, dcb->remote);
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}
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else
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{
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// No service found for user with correct username & host.
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// Check if a matching anonymous user exists.
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const string anon_query = string("SELECT authentication_string FROM ") + m_instance.m_tablename
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+ " WHERE " + FIELD_USER + " = ''"
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+ " AND '" + dcb->remote + "' LIKE " + FIELD_HOST
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+ " AND " + FIELD_PROXY + " = '1' ORDER BY authentication_string;";
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MXS_DEBUG("PAM proxy user services search sql: '%s'.", anon_query.c_str());
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if (sqlite3_exec(m_dbhandle, anon_query.c_str(), user_services_cb, services_out, &err) != SQLITE_OK)
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{
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MXS_ERROR("Failed to execute query: '%s'", err);
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sqlite3_free(err);
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}
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else
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{
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auto num_services = services_out->size();
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if (num_services == 0)
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{
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MXS_INFO("Found no PAM user entries for '%s'@'%s'.", session->user, dcb->remote);
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}
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else
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{
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MXS_INFO("Found %lu matching anonymous PAM user %s for '%s'@'%s'.",
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num_services, word_entry(num_services), session->user, dcb->remote);
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}
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}
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}
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}
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/**
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* @brief Create an AuthSwitchRequest packet
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*
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* The server (MaxScale) sends the plugin name "dialog" to the client with the
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* first password prompt. We want to avoid calling the PAM conversation function
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* more than once because it blocks, so we "emulate" its behaviour here.
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* This obviously only works with the basic password authentication scheme.
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*
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* @return Allocated packet
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* @see
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* https://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::AuthSwitchRequest
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*/
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Buffer PamClientSession::create_auth_change_packet() const
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{
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/**
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* The AuthSwitchRequest packet:
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* 4 bytes - Header
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* 0xfe - Command byte
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* string[NUL] - Auth plugin name
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* byte - Message type
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* string[EOF] - Message
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*/
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size_t plen = 1 + DIALOG_SIZE + 1 + PASSWORD.length();
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size_t buflen = MYSQL_HEADER_LEN + plen;
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uint8_t bufdata[buflen];
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uint8_t* pData = bufdata;
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gw_mysql_set_byte3(pData, plen);
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pData += 3;
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*pData++ = m_sequence;
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*pData++ = MYSQL_REPLY_AUTHSWITCHREQUEST;
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memcpy(pData, DIALOG.c_str(), DIALOG_SIZE); // Plugin name
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pData += DIALOG_SIZE;
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*pData++ = DIALOG_ECHO_DISABLED;
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memcpy(pData, PASSWORD.c_str(), PASSWORD.length()); // First message
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Buffer buffer(bufdata, buflen);
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return buffer;
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}
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int PamClientSession::authenticate(DCB* dcb)
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{
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int rval = MXS_AUTH_SSL_COMPLETE;
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MYSQL_session* ses = static_cast<MYSQL_session*>(dcb->data);
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if (*ses->user)
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{
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rval = MXS_AUTH_FAILED;
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if (m_state == State::INIT)
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{
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/** We need to send the authentication switch packet to change the
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* authentication to something other than the 'mysql_native_password'
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* method */
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Buffer authbuf = create_auth_change_packet();
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if (authbuf.length() && dcb->func.write(dcb, authbuf.release()))
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{
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m_state = State::ASKED_FOR_PW;
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rval = MXS_AUTH_INCOMPLETE;
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}
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}
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else if (m_state == State::PW_RECEIVED)
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{
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/** We sent the authentication change packet + plugin name and the client
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* responded with the password. Try to continue authentication without more
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* messages to client. */
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string password((char*)ses->auth_token, ses->auth_token_len);
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/*
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* Authentication may be attempted twice: first with old user account info and then with
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* updated info. Updating may fail if it has been attempted too often lately. The second password
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* check is useless if the user services are same as on the first attempt.
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*/
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bool authenticated = false;
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StringVector services_old;
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for (int loop = 0; loop < 2 && !authenticated; loop++)
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{
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if (loop == 0 || service_refresh_users(dcb->service) == 0)
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{
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bool try_validate = true;
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StringVector services;
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get_pam_user_services(dcb, ses, &services);
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if (loop == 0)
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{
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services_old = services;
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}
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else if (services == services_old)
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{
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try_validate = false;
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}
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if (try_validate)
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{
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for (auto iter = services.begin(); iter != services.end() && !authenticated; ++iter)
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{
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string service = *iter;
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// The server PAM plugin uses "mysql" as the default service when authenticating
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// a user with no service.
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if (service.empty())
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{
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service = "mysql";
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}
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mxb::PamResult res = mxb::pam_authenticate(ses->user, password, dcb->remote,
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service, PASSWORD);
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if (res.type == mxb::PamResult::Result::SUCCESS)
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{
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authenticated = true;
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}
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else
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{
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MXS_LOG_EVENT(maxscale::event::AUTHENTICATION_FAILURE, "%s",
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res.error.c_str());
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}
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}
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}
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}
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}
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if (authenticated)
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{
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rval = MXS_AUTH_SUCCEEDED;
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}
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m_state = State::DONE;
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}
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}
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return rval;
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}
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bool PamClientSession::extract(DCB* dcb, GWBUF* buffer)
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{
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gwbuf_copy_data(buffer, MYSQL_SEQ_OFFSET, 1, &m_sequence);
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m_sequence++;
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bool rval = false;
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switch (m_state)
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{
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case State::INIT:
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// The buffer doesn't have any PAM-specific data yet, as it's the normal HandShakeResponse.
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rval = true;
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break;
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case State::ASKED_FOR_PW:
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// Client should have responses with password.
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if (store_client_password(dcb, buffer))
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{
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m_state = State::PW_RECEIVED;
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rval = true;
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}
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break;
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default:
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MXS_ERROR("Unexpected authentication state: %d", static_cast<int>(m_state));
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mxb_assert(!true);
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break;
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}
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return rval;
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}
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