/* Copyright (c) 2010, 2019, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2.0, as published by the Free Software Foundation. This program is also distributed with certain software (including but not limited to OpenSSL) that is licensed under separate terms, as designated in a particular file or component or in included license documentation. The authors of MySQL hereby grant you an additional permission to link the program and your derivative works with the separately licensed software that they have included with MySQL. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0, for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ /** @file dialog client authentication plugin with examples dialog is a general purpose client authentication plugin, it simply asks the user the question, as provided by the server and reports the answer back to the server. No encryption is involved, the answers are sent in clear text. Two examples are provided: two_questions server plugin, that asks the password and an "Are you sure?" question with a reply "yes, of course". It demonstrates the usage of "password" (input is hidden) and "ordinary" (input can be echoed) questions, and how to mark the last question, to avoid an extra roundtrip. And three_attempts plugin that gives the user three attempts to enter a correct password. It shows the situation when a number of questions is not known in advance. */ #include "my_config.h" #if defined(WIN32) && !defined(RTLD_DEFAULT) #define RTLD_DEFAULT GetModuleHandle(NULL) #endif #include #include #include #include #include #include #include #include "my_compiler.h" #ifdef HAVE_DLFCN_H #include #endif #if !defined(_GNU_SOURCE) #define _GNU_SOURCE /* for RTLD_DEFAULT */ #endif /** first byte of the question string is the question "type". It can be an "ordinary" or a "password" question. The last bit set marks a last question in the authentication exchange. */ #define ORDINARY_QUESTION "\2" #define LAST_QUESTION "\3" #define PASSWORD_QUESTION "\4" #define LAST_PASSWORD "\5" /********************* SERVER SIDE ****************************************/ /** dialog demo with two questions, one password and one, the last, ordinary. */ static int two_questions(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info) { unsigned char *pkt; int pkt_len; /* send a password question */ if (vio->write_packet( vio, (const unsigned char *)PASSWORD_QUESTION "Password, please:", 18)) return CR_ERROR; /* read the answer */ if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR; info->password_used = PASSWORD_USED_YES; /* fail if the password is wrong */ if (strcmp((const char *)pkt, info->auth_string)) return CR_ERROR; /* send the last, ordinary, question */ if (vio->write_packet( vio, (const unsigned char *)LAST_QUESTION "Are you sure ?", 15)) return CR_ERROR; /* read the answer */ if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR; /* check the reply */ return strcmp((const char *)pkt, "yes, of course") ? CR_ERROR : CR_OK; } static int generate_auth_string_hash(char *outbuf, unsigned int *buflen, const char *inbuf, unsigned int inbuflen) { /* if buffer specified by server is smaller than the buffer given by plugin then return error */ if (*buflen < inbuflen) return 1; strncpy(outbuf, inbuf, inbuflen); *buflen = strlen(inbuf); return 0; } static int validate_auth_string_hash(char *const inbuf MY_ATTRIBUTE((unused)), unsigned int buflen MY_ATTRIBUTE((unused))) { return 0; } static int set_salt(const char *password MY_ATTRIBUTE((unused)), unsigned int password_len MY_ATTRIBUTE((unused)), unsigned char *salt MY_ATTRIBUTE((unused)), unsigned char *salt_len) { *salt_len = 0; return 0; } static struct st_mysql_auth two_handler = { MYSQL_AUTHENTICATION_INTERFACE_VERSION, "dialog", /* requires dialog client plugin */ two_questions, generate_auth_string_hash, validate_auth_string_hash, set_salt, AUTH_FLAG_PRIVILEGED_USER_FOR_PASSWORD_CHANGE, NULL}; /* dialog demo where the number of questions is not known in advance */ static int three_attempts(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info) { unsigned char *pkt; int pkt_len, i; for (i = 0; i < 3; i++) { /* send the prompt */ if (vio->write_packet( vio, (const unsigned char *)PASSWORD_QUESTION "Password, please:", 18)) return CR_ERROR; /* read the password */ if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR; info->password_used = PASSWORD_USED_YES; /* finish, if the password is correct. note, that we did not mark the prompt packet as "last" */ if (strcmp((const char *)pkt, info->auth_string) == 0) return CR_OK; } return CR_ERROR; } static struct st_mysql_auth three_handler = { MYSQL_AUTHENTICATION_INTERFACE_VERSION, "dialog", /* requires dialog client plugin */ three_attempts, generate_auth_string_hash, validate_auth_string_hash, set_salt, AUTH_FLAG_PRIVILEGED_USER_FOR_PASSWORD_CHANGE, NULL}; mysql_declare_plugin(dialog){ MYSQL_AUTHENTICATION_PLUGIN, &two_handler, "two_questions", "Sergei Golubchik", "Dialog plugin demo 1", PLUGIN_LICENSE_GPL, NULL, /* Init */ NULL, /* Check uninstall */ NULL, /* Deinit */ 0x0101, NULL, NULL, NULL, 0, }, { MYSQL_AUTHENTICATION_PLUGIN, &three_handler, "three_attempts", "Sergei Golubchik", "Dialog plugin demo 2", PLUGIN_LICENSE_GPL, NULL, /* Init */ NULL, /* Check uninstall */ NULL, /* Deinit */ 0x0101, NULL, NULL, NULL, 0, } mysql_declare_plugin_end; /********************* CLIENT SIDE ***************************************/ /* This plugin performs a dialog with the user, asking questions and reading answers. Depending on the client it may be desirable to do it using GUI, or console, with or without curses, or read answers from a smartcard, for example. To support all this variety, the dialog plugin has a callback function "authentication_dialog_ask". If the client has a function of this name dialog plugin will use it for communication with the user. Otherwise a default fgets() based implementation will be used. */ /** type of the mysql_authentication_dialog_ask function @param mysql mysql @param type type of the input 1 - ordinary string input 2 - password string @param prompt prompt @param buf a buffer to store the use input @param buf_len the length of the buffer @retval a pointer to the user input string. It may be equal to 'buf' or to 'mysql->password'. In all other cases it is assumed to be an allocated string, and the "dialog" plugin will free() it. */ typedef char *(*mysql_authentication_dialog_ask_t)(MYSQL *mysql, int type, const char *prompt, char *buf, int buf_len); static mysql_authentication_dialog_ask_t ask; static char *builtin_ask(MYSQL *mysql MY_ATTRIBUTE((unused)), int type MY_ATTRIBUTE((unused)), const char *prompt, char *buf, int buf_len) { char *ptr; fputs(prompt, stdout); fputc(' ', stdout); if (fgets(buf, buf_len, stdin) == NULL) return NULL; if ((ptr = strchr(buf, '\n'))) *ptr = 0; return buf; } /** The main function of the dialog plugin. Read the prompt, ask the question, send the reply, repeat until the server is satisfied. @note 1. this plugin shows how a client authentication plugin may read a MySQL protocol OK packet internally - which is important where a number of packets is not known in advance. 2. the first byte of the prompt is special. it is not shown to the user, but signals whether it is the last question (prompt[0] & 1 == 1) or not last (prompt[0] & 1 == 0), and whether the input is a password (not echoed). 3. the prompt is expected to be sent zero-terminated */ static int perform_dialog(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql) { unsigned char *pkt, cmd = 0; int pkt_len, res; char reply_buf[1024], *reply; do { /* read the prompt */ pkt_len = vio->read_packet(vio, &pkt); if (pkt_len < 0) return CR_ERROR; if (pkt == 0) { /* in mysql_change_user() the client sends the first packet, so the first vio->read_packet() does nothing (pkt == 0). We send the "password", assuming the client knows what it's doing. (in other words, the dialog plugin should be only set as a default authentication plugin on the client if the first question asks for a password - which will be sent in clear text, by the way) */ reply = mysql->passwd; } else { cmd = *pkt++; /* is it MySQL protocol packet ? */ if (cmd == 0 || cmd == 254) return CR_OK_HANDSHAKE_COMPLETE; /* yes. we're done */ /* asking for a password with an empty prompt means mysql->password otherwise we ask the user and read the reply */ if ((cmd >> 1) == 2 && *pkt == 0) reply = mysql->passwd; else reply = ask(mysql, cmd >> 1, (const char *)pkt, reply_buf, sizeof(reply_buf)); if (!reply) return CR_ERROR; } /* send the reply to the server */ res = vio->write_packet(vio, (const unsigned char *)reply, (int)strlen(reply) + 1); if (reply != mysql->passwd && reply != reply_buf) free(reply); if (res) return CR_ERROR; /* repeat unless it was the last question */ } while ((cmd & 1) != 1); /* the job of reading the ok/error packet is left to the server */ return CR_OK; } /** initialization function of the dialog plugin Pick up the client's authentication_dialog_ask() function, if exists, or fall back to the default implementation. */ static int init_dialog(char *unused1 MY_ATTRIBUTE((unused)), size_t unused2 MY_ATTRIBUTE((unused)), int unused3 MY_ATTRIBUTE((unused)), va_list unused4 MY_ATTRIBUTE((unused))) { void *sym = dlsym(RTLD_DEFAULT, "mysql_authentication_dialog_ask"); ask = sym ? (mysql_authentication_dialog_ask_t)sym : builtin_ask; return 0; } mysql_declare_client_plugin(AUTHENTICATION) "dialog", "Sergei Golubchik", "Dialog Client Authentication Plugin", {0, 1, 0}, "GPL", NULL, init_dialog, NULL, NULL, perform_dialog, NULL mysql_end_client_plugin;