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113 lines
3.3 KiB
C
113 lines
3.3 KiB
C
/*
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* Dropbear - a SSH2 server
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*
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* Copyright (c) 2002,2003 Matt Johnston
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE. */
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/* Validates a user password */
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#include "includes.h"
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#include "session.h"
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#include "buffer.h"
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#include "dbutil.h"
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#include "auth.h"
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#include "runopts.h"
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#ifdef ENABLE_SVR_PASSWORD_AUTH
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static int constant_time_strcmp(const char* a, const char* b) {
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size_t la = strlen(a);
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size_t lb = strlen(b);
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if (la != lb) {
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return 1;
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}
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return constant_time_memcmp(a, b, la);
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}
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/* Process a password auth request, sending success or failure messages as
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* appropriate */
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void svr_auth_password() {
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char * passwdcrypt = NULL; /* the crypt from /etc/passwd or /etc/shadow */
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char * testcrypt = NULL; /* crypt generated from the user's password sent */
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unsigned char * password;
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unsigned int passwordlen;
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unsigned int changepw;
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passwdcrypt = ses.authstate.pw_passwd;
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#ifdef DEBUG_HACKCRYPT
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/* debugging crypt for non-root testing with shadows */
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passwdcrypt = DEBUG_HACKCRYPT;
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#endif
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/* check if client wants to change password */
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changepw = buf_getbool(ses.payload);
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if (changepw) {
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/* not implemented by this server */
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send_msg_userauth_failure(0, 1);
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return;
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}
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password = buf_getstring(ses.payload, &passwordlen);
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/* the first bytes of passwdcrypt are the salt */
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testcrypt = crypt((char*)password, passwdcrypt);
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m_burn(password, passwordlen);
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m_free(password);
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if (testcrypt == NULL) {
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/* crypt() with an invalid salt like "!!" */
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dropbear_log(LOG_WARNING, "User account '%s' is locked",
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ses.authstate.pw_name);
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send_msg_userauth_failure(0, 1);
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return;
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}
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/* check for empty password */
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if (passwdcrypt[0] == '\0') {
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dropbear_log(LOG_WARNING, "User '%s' has blank password, rejected",
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ses.authstate.pw_name);
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send_msg_userauth_failure(0, 1);
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return;
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}
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if (constant_time_strcmp(testcrypt, passwdcrypt) == 0) {
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/* successful authentication */
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dropbear_log(LOG_NOTICE,
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"Password auth succeeded for '%s' from %s",
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ses.authstate.pw_name,
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svr_ses.addrstring);
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send_msg_userauth_success();
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} else {
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dropbear_log(LOG_WARNING,
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"Bad password attempt for '%s' from %s",
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ses.authstate.pw_name,
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svr_ses.addrstring);
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send_msg_userauth_failure(0, 1);
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}
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}
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#endif
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