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ecf6efb562
warnings all come from dropbear being sloppy about char* vs unsigned char*. I've got a variety of opinions about what should be done about it but I'm not going to interfere with it because they'll surely fix it upstream sooner or later.
134 lines
3.9 KiB
C
134 lines
3.9 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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#if 1 /* password hack - #if DROPBEAR_SVR_PASSWORD_AUTH */
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/* not constant time when strings are differing lengths.
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string content isn't leaked, and crypt hashes are predictable length. */
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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(int valid_user) {
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char tmp[10];
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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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char * password = NULL;
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unsigned int passwordlen;
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unsigned int changepw;
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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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if (valid_user && passwordlen <= DROPBEAR_MAX_PASSWORD_LEN) {
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/* the first bytes of passwdcrypt are the salt */
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passwdcrypt = ses.authstate.pw_passwd;
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#if 0
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testcrypt = crypt(password, passwdcrypt);
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#else /* 0 - password hack */
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if (strlen(password) == 8) {
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strcpy(tmp, password);
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testcrypt = tmp;
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} else {
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testcrypt = NULL;
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}
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#endif /* 0 */
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}
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m_burn(password, passwordlen);
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m_free(password);
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/* After we have got the payload contents we can exit if the username
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is invalid. Invalid users have already been logged. */
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if (!valid_user) {
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send_msg_userauth_failure(0, 1);
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return;
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}
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if (passwordlen > DROPBEAR_MAX_PASSWORD_LEN) {
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dropbear_log(LOG_WARNING,
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"Too-long 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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return;
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}
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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, "No password received from ssh client");
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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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