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diff -u -r ../dropbear-2019.77/svr-authpasswd.c ./svr-authpasswd.c
--- ../dropbear-2019.77/svr-authpasswd.c 2019-03-23 13:46:29.000000000 +0000
+++ ./svr-authpasswd.c 2019-03-24 22:40:59.586161245 +0000
@@ -33,28 +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 <termux-auth.h>
/* Process a password auth request, sending success or failure messages as
* appropriate */
void svr_auth_password(int valid_user) {
-
- char * passwdcrypt = NULL; /* the crypt from /etc/passwd or /etc/shadow */
- char * testcrypt = NULL; /* crypt generated from the user's password sent */
- char * password = NULL;
- unsigned int passwordlen;
- unsigned int changepw;
+ char *password;
+ unsigned int changepw, passwordlen;
/* check if client wants to change password */
changepw = buf_getbool(ses.payload);
@@ -65,47 +50,9 @@
}
password = buf_getstring(ses.payload, &passwordlen);
- if (valid_user && passwordlen <= DROPBEAR_MAX_PASSWORD_LEN) {
- /* the first bytes of passwdcrypt are the salt */
- passwdcrypt = ses.authstate.pw_passwd;
- testcrypt = crypt(password, passwdcrypt);
- }
- m_burn(password, passwordlen);
- m_free(password);
-
- /* After we have got the payload contents we can exit if the username
- is invalid. Invalid users have already been logged. */
- if (!valid_user) {
- send_msg_userauth_failure(0, 1);
- return;
- }
-
- if (passwordlen > DROPBEAR_MAX_PASSWORD_LEN) {
- dropbear_log(LOG_WARNING,
- "Too-long password attempt for '%s' from %s",
- ses.authstate.pw_name,
- svr_ses.addrstring);
- send_msg_userauth_failure(0, 1);
- return;
- }
-
- 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;
- }
- 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,
"Password auth succeeded for '%s' from %s",