cli-authinteract.c

   1 /*
   2  * Dropbear SSH
   3  *
   4  * Copyright (c) 2005 Matt Johnston
   5  * All rights reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE. */
  24
  25 #include "includes.h"
  26 #include "buffer.h"
  27 #include "dbutil.h"
  28 #include "session.h"
  29 #include "ssh.h"
  30 #include "runopts.h"
  31
  32 #ifdef ENABLE_CLI_INTERACT_AUTH
  33
  34 static unsigned char* get_response(unsigned char* prompt)
  35 {
  36         FILE* tty = NULL;
  37         unsigned char* response = NULL;
  38         /* not a password, but a reasonable limit */
  39         char buf[DROPBEAR_MAX_CLI_PASS];
  40         char* ret = NULL;
  41
  42         fprintf(stderr, "%s", prompt);
  43
  44         tty = fopen(_PATH_TTY, "r");
  45         if (tty) {
  46                 ret = fgets(buf, sizeof(buf), tty);
  47                 fclose(tty);
  48         } else {
  49                 ret = fgets(buf, sizeof(buf), stdin);
  50         }
  51
  52         if (ret == NULL) {
  53                 response = (unsigned char*)m_strdup("");
  54         } else {
  55                 unsigned int buflen = strlen(buf);
  56                 /* fgets includes newlines */
  57                 if (buflen > 0 && buf[buflen-1] == '\n')
  58                         buf[buflen-1] = '\0';
  59                 response = (unsigned char*)m_strdup(buf);
  60         }
  61
  62         m_burn(buf, sizeof(buf));
  63
  64         return response;
  65 }
  66
  67 void recv_msg_userauth_info_request() {
  68
  69         unsigned char *name = NULL;
  70         unsigned char *instruction = NULL;
  71         unsigned int num_prompts = 0;
  72         unsigned int i;
  73
  74         unsigned char *prompt = NULL;
  75         unsigned int echo = 0;
  76         unsigned char *response = NULL;
  77
  78         TRACE(("enter recv_msg_recv_userauth_info_request"))
  79
  80         /* Let the user know what password/host they are authing for */
  81         if (!cli_ses.interact_request_received) {
  82                 fprintf(stderr, "Login for %s@%s\n", cli_opts.username,
  83                                 cli_opts.remotehost);
  84         }
  85         cli_ses.interact_request_received = 1;
  86
  87         name = buf_getstring(ses.payload, NULL);
  88         instruction = buf_getstring(ses.payload, NULL);
  89
  90         /* language tag */
  91         buf_eatstring(ses.payload);
  92
  93         num_prompts = buf_getint(ses.payload);
  94
  95         if (num_prompts >= DROPBEAR_MAX_CLI_INTERACT_PROMPTS) {
  96                 dropbear_exit("Too many prompts received for keyboard-interactive");
  97         }
  98
  99         /* we'll build the response as we go */
 100         CHECKCLEARTOWRITE();
 101         buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_INFO_RESPONSE);
 102         buf_putint(ses.writepayload, num_prompts);
 103
 104         if (strlen(name) > 0) {
 105                 cleantext(name);
 106                 fprintf(stderr, "%s", name);
 107         }
 108         m_free(name);
 109
 110         if (strlen(instruction) > 0) {
 111                 cleantext(instruction);
 112                 fprintf(stderr, "%s", instruction);
 113         }
 114         m_free(instruction);
 115
 116         for (i = 0; i < num_prompts; i++) {
 117                 unsigned int response_len = 0;
 118                 prompt = buf_getstring(ses.payload, NULL);
 119                 cleantext(prompt);
 120
 121                 echo = buf_getbool(ses.payload);
 122
 123                 if (!echo) {
 124                         unsigned char* p = getpass_or_cancel(prompt);
 125                         response = m_strdup(p);
 126                         m_burn(p, strlen(p));
 127                 } else {
 128                         response = get_response(prompt);
 129                 }
 130
 131                 response_len = strlen(response);
 132                 buf_putstring(ses.writepayload, response, response_len);
 133                 m_burn(response, response_len);
 134                 m_free(response);
 135         }
 136
 137         encrypt_packet();
 138
 139
 140         TRACE(("leave recv_msg_recv_userauth_info_request"))
 141 }
 142
 143 void cli_auth_interactive() {
 144
 145         TRACE(("enter cli_auth_interactive"))
 146         CHECKCLEARTOWRITE();
 147
 148         buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);
 149
 150         /* username */
 151         buf_putstring(ses.writepayload, cli_opts.username,
 152                         strlen(cli_opts.username));
 153
 154         /* service name */
 155         buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION,
 156                         SSH_SERVICE_CONNECTION_LEN);
 157
 158         /* method */
 159         buf_putstring(ses.writepayload, AUTH_METHOD_INTERACT,
 160                         AUTH_METHOD_INTERACT_LEN);
 161
 162         /* empty language tag */
 163         buf_putstring(ses.writepayload, "", 0);
 164
 165         /* empty submethods */
 166         buf_putstring(ses.writepayload, "", 0);
 167
 168         encrypt_packet();
 169         cli_ses.interact_request_received = 0;
 170
 171         TRACE(("leave cli_auth_interactive"))
 172
 173 }
 174 #endif  /* ENABLE_CLI_INTERACT_AUTH */