diff -uNr dropbear-2018.76/svr-authpasswd.c dropbear-2018.76.mod/svr-authpasswd.c --- dropbear-2018.76/svr-authpasswd.c 2018-02-27 16:25:12.000000000 +0200 +++ dropbear-2018.76.mod/svr-authpasswd.c 2018-10-21 14:05:37.774231619 +0300 @@ -33,36 +33,13 @@ #if DROPBEAR_SVR_PASSWORD_AUTH -/* not constant time when strings are differing lengths. - string content isn't leaked, and crypt hashes are predictable length. */ -static int constant_time_strcmp(const char* a, const char* b) { - size_t la = strlen(a); - size_t lb = strlen(b); - - if (la != lb) { - return 1; - } - - return constant_time_memcmp(a, b, la); -} +#include /* Process a password auth request, sending success or failure messages as * appropriate */ void svr_auth_password() { - - char * passwdcrypt = NULL; /* the crypt from /etc/passwd or /etc/shadow */ - char * testcrypt = NULL; /* crypt generated from the user's password sent */ - char * password; - unsigned int passwordlen; - - unsigned int changepw; - - passwdcrypt = ses.authstate.pw_passwd; - -#ifdef DEBUG_HACKCRYPT - /* debugging crypt for non-root testing with shadows */ - passwdcrypt = DEBUG_HACKCRYPT; -#endif + char *password; + unsigned int changepw, passwordlen; /* check if client wants to change password */ changepw = buf_getbool(ses.payload); @@ -72,43 +49,23 @@ return; } - password = buf_getstring(ses.payload, &passwordlen); - - /* the first bytes of passwdcrypt are the salt */ - testcrypt = crypt(password, passwdcrypt); - m_burn(password, passwordlen); - m_free(password); - - if (testcrypt == NULL) { - /* crypt() with an invalid salt like "!!" */ - dropbear_log(LOG_WARNING, "User account '%s' is locked", - ses.authstate.pw_name); - send_msg_userauth_failure(0, 1); - return; - } - - /* check for empty password */ - if (passwdcrypt[0] == '\0') { - dropbear_log(LOG_WARNING, "User '%s' has blank password, rejected", - ses.authstate.pw_name); - send_msg_userauth_failure(0, 1); - return; - } + password = buf_getstring(ses.payload, &passwordlen); - if (constant_time_strcmp(testcrypt, passwdcrypt) == 0) { + /* check if password is valid */ + if (termux_auth(ses.authstate.pw_name, password)) { /* successful authentication */ - dropbear_log(LOG_NOTICE, + dropbear_log(LOG_NOTICE, "Password auth succeeded for '%s' from %s", ses.authstate.pw_name, svr_ses.addrstring); send_msg_userauth_success(); - } else { + } else { dropbear_log(LOG_WARNING, "Bad password attempt for '%s' from %s", ses.authstate.pw_name, svr_ses.addrstring); send_msg_userauth_failure(0, 1); - } + } } #endif