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Updated "login_yubikey.c" for OpenBSD that adds /var/db/yubi/$user.pin with additional user pin/password that must be entered with Yubikey token.
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/* $OpenBSD: login_yubikey.c,v 1.8 2013/11/27 21:25:25 deraadt Exp $ */ | |
/* | |
* Copyright (c) 2010 Daniel Hartmeier <daniel@benzedrine.cx> | |
* All rights reserved. | |
* | |
* Redistribution and use in source and binary forms, with or without | |
* modification, are permitted provided that the following conditions | |
* are met: | |
* | |
* - Redistributions of source code must retain the above copyright | |
* notice, this list of conditions and the following disclaimer. | |
* - Redistributions in binary form must reproduce the above | |
* copyright notice, this list of conditions and the following | |
* disclaimer in the documentation and/or other materials provided | |
* with the distribution. | |
* | |
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | |
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | |
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
* POSSIBILITY OF SUCH DAMAGE. | |
* | |
*/ | |
#include <sys/param.h> | |
#include <sys/stat.h> | |
#include <sys/time.h> | |
#include <sys/resource.h> | |
#include <ctype.h> | |
#include <login_cap.h> | |
#include <pwd.h> | |
#include <stdarg.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <syslog.h> | |
#include <unistd.h> | |
#include <errno.h> | |
#include <util.h> | |
#include "yubikey.h" | |
#define MODE_LOGIN 0 | |
#define MODE_CHALLENGE 1 | |
#define MODE_RESPONSE 2 | |
#define AUTH_OK 0 | |
#define AUTH_FAILED -1 | |
#define YUBIKEY_LENGTH 44 | |
static const char *path = "/var/db/yubikey"; | |
static int clean_string(const char *); | |
static int yubikey_login(const char *, const char *); | |
static int pin_login(const char *, const char *); | |
int | |
main(int argc, char *argv[]) | |
{ | |
int ch, ret, ret_pin, mode = MODE_LOGIN; | |
FILE *f = NULL; | |
char *username, *password = NULL; | |
char response[1024]; | |
setpriority(PRIO_PROCESS, 0, 0); | |
openlog(NULL, LOG_ODELAY, LOG_AUTH); | |
while ((ch = getopt(argc, argv, "dv:s:")) != -1) { | |
switch (ch) { | |
case 'd': | |
f = stdout; | |
break; | |
case 'v': | |
break; | |
case 's': | |
if (!strcmp(optarg, "login")) | |
mode = MODE_LOGIN; | |
else if (!strcmp(optarg, "response")) | |
mode = MODE_RESPONSE; | |
else if (!strcmp(optarg, "challenge")) | |
mode = MODE_CHALLENGE; | |
else { | |
syslog(LOG_ERR, "%s: invalid service", optarg); | |
exit(EXIT_FAILURE); | |
} | |
break; | |
default: | |
syslog(LOG_ERR, "usage error1"); | |
exit(EXIT_FAILURE); | |
} | |
} | |
argc -= optind; | |
argv += optind; | |
if (argc != 2 && argc != 1) { | |
syslog(LOG_ERR, "usage error2"); | |
exit(EXIT_FAILURE); | |
} | |
username = argv[0]; | |
/* passed by sshd(8) for non-existing users */ | |
if (!strcmp(username, "NOUSER")) | |
exit(EXIT_FAILURE); | |
if (!clean_string(username)) { | |
syslog(LOG_ERR, "clean_string username"); | |
exit(EXIT_FAILURE); | |
} | |
if (f == NULL && (f = fdopen(3, "r+")) == NULL) { | |
syslog(LOG_ERR, "user %s: fdopen: %m", username); | |
exit(EXIT_FAILURE); | |
} | |
switch (mode) { | |
case MODE_LOGIN: | |
if ((password = getpass("Password:")) == NULL) { | |
syslog(LOG_ERR, "user %s: getpass: %m", | |
username); | |
exit(EXIT_FAILURE); | |
} | |
break; | |
case MODE_CHALLENGE: | |
/* see login.conf(5) section CHALLENGES */ | |
fprintf(f, "%s\n", BI_SILENT); | |
exit(EXIT_SUCCESS); | |
break; | |
case MODE_RESPONSE: { | |
/* see login.conf(5) section RESPONSES */ | |
/* this happens e.g. when called from sshd(8) */ | |
int count; | |
mode = 0; | |
count = -1; | |
while (++count < sizeof(response) && | |
read(3, &response[count], (size_t)1) == | |
(ssize_t)1) { | |
if (response[count] == '\0' && ++mode == 2) | |
break; | |
if (response[count] == '\0' && mode == 1) { | |
password = response + count + 1; | |
} | |
} | |
if (mode < 2) { | |
syslog(LOG_ERR, "user %s: protocol error " | |
"on back channel", username); | |
exit(EXIT_FAILURE); | |
} | |
break; | |
} | |
} | |
int password_length = strlen(password)-YUBIKEY_LENGTH; | |
/* if the password length < 0 that means this isn't even long enough to contain a valid yubi token */ | |
if (password_length < 0) { | |
syslog(LOG_INFO, "user %s: reject", username); | |
fprintf(f, "%s\n ", BI_REJECT); | |
closelog(); | |
return (EXIT_SUCCESS); | |
} | |
char password_pin[password_length +1]; | |
char password_yubi[YUBIKEY_LENGTH + 1]; | |
/* first password_length bytes are PIN */ | |
strlcpy(password_pin, password, password_length + 1); | |
/* remaining 44 bytes are yubikey token */ | |
strlcpy(password_yubi, (char*)password + password_length, YUBIKEY_LENGTH + 1); | |
ret = yubikey_login(username, password_yubi); | |
ret_pin = pin_login(username, password_pin); | |
memset(password, 0, strlen(password)); | |
memset(password_pin, 0, strlen(password_pin)); | |
memset(password_yubi, 0, strlen(password_yubi)); | |
if (ret == AUTH_OK && ret_pin == AUTH_OK) { /* successfull login calls both yubi/pin code and requires AUTH_OK from both */ | |
syslog(LOG_INFO, "user %s: authorize", username); | |
fprintf(f, "%s\n", BI_AUTH); | |
} else { | |
syslog(LOG_INFO, "user %s: reject", username); | |
fprintf(f, "%s\n", BI_REJECT); | |
} | |
closelog(); | |
return (EXIT_SUCCESS); | |
} | |
static int | |
clean_string(const char *s) | |
{ | |
while (*s) { | |
if (!isalnum((unsigned char)*s) && *s != '-' && *s != '_') | |
return (0); | |
++s; | |
} | |
return (1); | |
} | |
static int | |
pin_login(const char *username, const char *pin) | |
{ | |
char fn[MAXPATHLEN]; | |
FILE *f; | |
char encrypted_pin[101]; // pin is salted/hashed (crypt) | |
snprintf(fn, sizeof(fn), "%s/%s.pin", path, username); | |
if ((f = fopen(fn, "r")) == NULL) { | |
if (strlen(pin) > 0) { | |
syslog(LOG_ERR, "user %s: fopen: %s: %m", username, fn); | |
return (AUTH_FAILED); | |
} else { | |
/* if pin is empty and file is missing revert to original behaviour */ | |
return (AUTH_OK); | |
} | |
} | |
if (fscanf(f, "%100s", encrypted_pin) != 1) { | |
syslog(LOG_ERR, "user %s: fscanf: %s: %m", username, fn); | |
fclose(f); | |
return (AUTH_FAILED); | |
} | |
fclose(f); | |
char* salted_pin = crypt(pin, encrypted_pin); | |
if (strcmp(salted_pin, encrypted_pin) != 0) | |
return (AUTH_FAILED); | |
return (AUTH_OK); | |
}; | |
static int | |
yubikey_login(const char *username, const char *password) | |
{ | |
char fn[MAXPATHLEN]; | |
char hexkey[33], key[YUBIKEY_KEY_SIZE]; | |
char hexuid[13], uid[YUBIKEY_UID_SIZE]; | |
FILE *f; | |
yubikey_token_st tok; | |
u_int32_t last_ctr = 0, ctr; | |
int r, i = 0, mapok = 0, crcok = 0; | |
snprintf(fn, sizeof(fn), "%s/%s.uid", path, username); | |
if ((f = fopen(fn, "r")) == NULL) { | |
syslog(LOG_ERR, "user %s: fopen: %s: %m", username, fn); | |
return (AUTH_FAILED); | |
} | |
if (fscanf(f, "%12s", hexuid) != 1) { | |
syslog(LOG_ERR, "user %s: fscanf: %s: %m", username, fn); | |
fclose(f); | |
return (AUTH_FAILED); | |
} | |
fclose(f); | |
snprintf(fn, sizeof(fn), "%s/%s.key", path, username); | |
if ((f = fopen(fn, "r")) == NULL) { | |
syslog(LOG_ERR, "user %s: fopen: %s: %m", username, fn); | |
return (AUTH_FAILED); | |
} | |
if (fscanf(f, "%32s", hexkey) != 1) { | |
syslog(LOG_ERR, "user %s: fscanf: %s: %m", username, fn); | |
fclose(f); | |
return (AUTH_FAILED); | |
} | |
fclose(f); | |
if (strlen(hexkey) != 32) { | |
syslog(LOG_ERR, "user %s: key len != 32", username); | |
return (AUTH_FAILED); | |
} | |
snprintf(fn, sizeof(fn), "%s/%s.ctr", path, username); | |
if ((f = fopen(fn, "r")) != NULL) { | |
if (fscanf(f, "%u", &last_ctr) != 1) | |
last_ctr = 0; | |
fclose(f); | |
} | |
yubikey_hex_decode(uid, hexuid, YUBIKEY_UID_SIZE); | |
yubikey_hex_decode(key, hexkey, YUBIKEY_KEY_SIZE); | |
/* | |
* Cycle through the key mapping table. | |
* XXX brute force, unoptimized; a lookup table for valid mappings may | |
* be appropriate. | |
*/ | |
while (1) { | |
r = yubikey_parse((uint8_t *)password, (uint8_t *)key, &tok, i++); | |
switch (r) { | |
case EMSGSIZE: | |
syslog(LOG_INFO, "user %s failed: password too short.", | |
username); | |
return (AUTH_FAILED); | |
case EINVAL: /* keyboard mapping invalid */ | |
continue; | |
case 0: /* found a valid keyboard mapping */ | |
mapok++; | |
if (!yubikey_crc_ok_p((uint8_t *)&tok)) | |
continue; /* try another one */ | |
crcok++; | |
syslog(LOG_DEBUG, "user %s: crc %04x ok", | |
username, tok.crc); | |
if (memcmp(tok.uid, uid, YUBIKEY_UID_SIZE)) { | |
char h[13]; | |
yubikey_hex_encode(h, (const char *)tok.uid, | |
YUBIKEY_UID_SIZE); | |
syslog(LOG_DEBUG, "user %s: uid %s != %s", | |
username, h, hexuid); | |
continue; /* try another one */ | |
} | |
break; /* uid matches */ | |
case -1: | |
syslog(LOG_INFO, "user %s: could not decode password" | |
"with any keymap (%d crc ok)", | |
username, crcok); | |
return (AUTH_FAILED); | |
default: | |
syslog(LOG_DEBUG, "user %s failed: %s", | |
username, strerror(r)); | |
return (AUTH_FAILED); | |
} | |
break; /* only reached through the bottom of case 0 */ | |
} | |
syslog(LOG_INFO, "user %s uid %s: %d matching keymaps (%d checked), " | |
"%d crc ok", username, hexuid, mapok, i, crcok); | |
ctr = ((u_int32_t)yubikey_counter(tok.ctr) << 8) | tok.use; | |
if (ctr <= last_ctr) { | |
syslog(LOG_INFO, "user %s: counter %u.%u <= %u.%u " | |
"(REPLAY ATTACK!)", username, ctr / 256, ctr % 256, | |
last_ctr / 256, last_ctr % 256); | |
return (AUTH_FAILED); | |
} | |
syslog(LOG_INFO, "user %s: counter %u.%u > %u.%u", | |
username, ctr / 256, ctr % 256, last_ctr / 256, last_ctr % 256); | |
umask(S_IRWXO); | |
if ((f = fopen(fn, "w")) == NULL) { | |
syslog(LOG_ERR, "user %s: fopen: %s: %m", username, fn); | |
return (AUTH_FAILED); | |
} | |
fprintf(f, "%u", ctr); | |
fclose(f); | |
return (AUTH_OK); | |
} |
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Can generate passwords using encrypt(1). Something like the following...
echo "password" | encrypt > /var/db/yubi/$user.pin