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openssh-portable/auth-passwd.c

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/* $OpenBSD: auth-passwd.c,v 1.46 2018/03/03 03:15:51 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Password authentication. This file contains the functions to check whether
* the password is valid for the user.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* Copyright (c) 1999 Dug Song. All rights reserved.
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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 AUTHOR ``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 AUTHOR 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 "includes.h"
#include <sys/types.h>
#include <pwd.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "misc.h"
#include "servconf.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "authfd.h"
#ifdef WINDOWS
#include "w32api_proxies.h"
#include "misc_internal.h"
#endif
extern Buffer loginmsg;
extern ServerOptions options;
#ifdef HAVE_LOGIN_CAP
extern login_cap_t *lc;
#endif
#define DAY (24L * 60 * 60) /* 1 day in seconds */
#define TWO_WEEKS (2L * 7 * DAY) /* 2 weeks in seconds */
#define MAX_PASSWORD_LEN 1024
/*
* Tries to authenticate the user using password. Returns true if
* authentication succeeds.
*/
int
auth_password(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
struct passwd *pw = authctxt->pw;
int result, ok = authctxt->valid;
#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
static int expire_checked = 0;
#endif
if (strlen(password) > MAX_PASSWORD_LEN)
return 0;
#ifndef HAVE_CYGWIN
if (pw->pw_uid == 0 && options.permit_root_login != PERMIT_YES)
ok = 0;
#endif
if (*password == '\0' && options.permit_empty_passwd == 0)
return 0;
#ifdef KRB5
if (options.kerberos_authentication == 1) {
int ret = auth_krb5_password(authctxt, password);
if (ret == 1 || ret == 0)
return ret && ok;
/* Fall back to ordinary passwd authentication. */
}
#endif
#ifdef HAVE_CYGWIN
{
HANDLE hToken = cygwin_logon_user(pw, password);
if (hToken == INVALID_HANDLE_VALUE)
return 0;
cygwin_set_impersonation_token(hToken);
return ok;
}
#endif
#ifdef USE_PAM
if (options.use_pam)
return (sshpam_auth_passwd(authctxt, password) && ok);
#endif
#if defined(USE_SHADOW) && defined(HAS_SHADOW_EXPIRE)
if (!expire_checked) {
expire_checked = 1;
if (auth_shadow_pwexpired(authctxt))
authctxt->force_pwchange = 1;
}
#endif
result = sys_auth_passwd(ssh, password);
if (authctxt->force_pwchange)
auth_restrict_session(ssh);
return (result && ok);
}
#ifdef BSD_AUTH
static void
warn_expiry(Authctxt *authctxt, auth_session_t *as)
{
char buf[256];
quad_t pwtimeleft, actimeleft, daysleft, pwwarntime, acwarntime;
pwwarntime = acwarntime = TWO_WEEKS;
pwtimeleft = auth_check_change(as);
actimeleft = auth_check_expire(as);
#ifdef HAVE_LOGIN_CAP
if (authctxt->valid) {
pwwarntime = login_getcaptime(lc, "password-warn", TWO_WEEKS,
TWO_WEEKS);
acwarntime = login_getcaptime(lc, "expire-warn", TWO_WEEKS,
TWO_WEEKS);
}
#endif
if (pwtimeleft != 0 && pwtimeleft < pwwarntime) {
daysleft = pwtimeleft / DAY + 1;
snprintf(buf, sizeof(buf),
"Your password will expire in %lld day%s.\n",
daysleft, daysleft == 1 ? "" : "s");
buffer_append(&loginmsg, buf, strlen(buf));
}
if (actimeleft != 0 && actimeleft < acwarntime) {
daysleft = actimeleft / DAY + 1;
snprintf(buf, sizeof(buf),
"Your account will expire in %lld day%s.\n",
daysleft, daysleft == 1 ? "" : "s");
buffer_append(&loginmsg, buf, strlen(buf));
}
}
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
auth_session_t *as;
static int expire_checked = 0;
as = auth_usercheck(authctxt->pw->pw_name, authctxt->style, "auth-ssh",
(char *)password);
if (as == NULL)
return (0);
if (auth_getstate(as) & AUTH_PWEXPIRED) {
auth_close(as);
auth_restrict_session(ssh);
authctxt->force_pwchange = 1;
return (1);
} else {
if (!expire_checked) {
expire_checked = 1;
warn_expiry(authctxt, as);
}
return (auth_close(as));
}
}
#elif !defined(CUSTOM_SYS_AUTH_PASSWD)
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
Authctxt *authctxt = ssh->authctxt;
struct passwd *pw = authctxt->pw;
char *encrypted_password, *salt = NULL;
/* Just use the supplied fake password if authctxt is invalid */
char *pw_password = authctxt->valid ? shadow_pw(pw) : pw->pw_passwd;
/* Check for users with no password. */
if (strcmp(pw_password, "") == 0 && strcmp(password, "") == 0)
return (1);
/*
* Encrypt the candidate password using the proper salt, or pass a
* NULL and let xcrypt pick one.
*/
if (authctxt->valid && pw_password[0] && pw_password[1])
salt = pw_password;
encrypted_password = xcrypt(password, salt);
/*
* Authentication is accepted if the encrypted passwords
* are identical.
*/
return encrypted_password != NULL &&
strcmp(encrypted_password, pw_password) == 0;
}
#elif defined(WINDOWS)
HANDLE password_auth_token = NULL;
HANDLE process_custom_lsa_auth(const char*, const char*, const char*);
void
sys_auth_passwd_lsa(Authctxt *authctxt, const char *password)
{
char *lsa_auth_pkg = NULL;
wchar_t *lsa_auth_pkg_w = NULL;
int domain_len = 0, lsa_auth_pkg_len = 0;
HKEY reg_key = 0;
REGSAM mask = STANDARD_RIGHTS_READ | KEY_QUERY_VALUE | KEY_WOW64_64KEY;
if ((RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SOFTWARE\\OpenSSH", 0, mask, &reg_key) == ERROR_SUCCESS) &&
(RegQueryValueExW(reg_key, L"LSAAuthenticationPackage", 0, NULL, NULL, &lsa_auth_pkg_len) == ERROR_SUCCESS)) {
lsa_auth_pkg_w = (wchar_t *) malloc(lsa_auth_pkg_len); // lsa_auth_pkg_len includes the null terminating character.
if (!lsa_auth_pkg_w)
fatal("%s: out of memory", __func__);
memset(lsa_auth_pkg_w, 0, lsa_auth_pkg_len);
if (RegQueryValueExW(reg_key, L"LSAAuthenticationPackage", 0, NULL, (LPBYTE)lsa_auth_pkg_w, &lsa_auth_pkg_len) == ERROR_SUCCESS) {
lsa_auth_pkg = utf16_to_utf8(lsa_auth_pkg_w);
if (!lsa_auth_pkg)
fatal("utf16_to_utf8 failed to convert lsa_auth_pkg_w:%ls", lsa_auth_pkg_w);
password_auth_token = process_custom_lsa_auth(authctxt->pw->pw_name, password, lsa_auth_pkg);
}
}
done:
if (lsa_auth_pkg_w)
free(lsa_auth_pkg_w);
if (lsa_auth_pkg)
free(lsa_auth_pkg);
if (reg_key)
RegCloseKey(reg_key);
}
/*
* Authenticate on Windows
* - Call LogonUser and retrieve user token
* - If LogonUser fails, then try the LSA (Local Security Authority) authentication.
*/
int
sys_auth_passwd(struct ssh *ssh, const char *password)
{
wchar_t *user_utf16 = NULL, *pwd_utf16 = NULL, *unam_utf16 = NULL, *udom_utf16 = L".";
Authctxt *authctxt = ssh->authctxt;
HANDLE token = NULL;
WCHAR domain_upn[MAX_UPN_LEN + 1];
ULONG domain_upn_len = ARRAYSIZE(domain_upn);
user_utf16 = utf8_to_utf16(authctxt->pw->pw_name);
pwd_utf16 = utf8_to_utf16(password);
if (user_utf16 == NULL || pwd_utf16 == NULL) {
debug("out of memory");
goto done;
}
/* the format for the user will be constrained to the output of get_passwd()
* so only the only two formats are NetBiosDomain\SamAccountName which is
* a domain account or just SamAccountName in which is a local account */
/* default assumption - local user */
unam_utf16 = user_utf16;
/* translate to domain user if format contains a backslash */
wchar_t * backslash = wcschr(user_utf16, L'\\');
if (backslash != NULL) {
/* attempt to format into upn format as this is preferred for login */
if (pTranslateNameW(user_utf16, NameSamCompatible, NameUserPrincipal, domain_upn, &domain_upn_len) != 0) {
debug3("%s: Successfully discovered principal name: '%ls'=>'%ls'",
__FUNCTION__, user_utf16, domain_upn);
unam_utf16 = domain_upn;
udom_utf16 = NULL;
}
/* user likely does not have upn so just use SamCompatibleName */
else {
debug3("%s: Unable to discover principal name for user '%ls': %d",
__FUNCTION__, user_utf16, GetLastError());
*backslash = '\0';
unam_utf16 = backslash + 1;
udom_utf16 = user_utf16;
}
}
if (pLogonUserExExW(unam_utf16, udom_utf16, pwd_utf16, LOGON32_LOGON_NETWORK_CLEARTEXT,
LOGON32_PROVIDER_DEFAULT, NULL, &token, NULL, NULL, NULL, NULL) == TRUE)
password_auth_token = token;
else {
if (GetLastError() == ERROR_PASSWORD_MUST_CHANGE)
/*
* TODO - need to add support to force password change
* by sending back SSH_MSG_USERAUTH_PASSWD_CHANGEREQ
*/
error("password for user %s has expired", authctxt->pw->pw_name);
else {
debug("Windows authentication failed for user: %ls domain: %ls error: %d",
unam_utf16, udom_utf16, GetLastError());
/* If LSA authentication package is configured then it will return the auth_token */
sys_auth_passwd_lsa(authctxt, password);
}
}
done:
if (user_utf16)
free(user_utf16);
if (pwd_utf16)
SecureZeroMemory(pwd_utf16, sizeof(wchar_t) * wcslen(pwd_utf16));
return (password_auth_token) ? 1 : 0;
}
#endif /* WINDOWS */
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