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/*
Unix SMB/CIFS implementation.
Authenticate to a remote server
Copyright (C) Andrew Tridgell 1992-1998
Copyright (C) Andrew Bartlett 2001
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#undef DBGC_CLASS
#define DBGC_CLASS DBGC_AUTH
extern userdom_struct current_user_info;
/****************************************************************************
Support for server level security.
****************************************************************************/
static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
{
struct cli_state *cli = NULL;
fstring desthost;
struct in_addr dest_ip;
const char *p;
char *pserver;
bool connected_ok = False;
if (!(cli = cli_initialise()))
return NULL;
/* security = server just can't function with spnego */
cli->use_spnego = False;
pserver = talloc_strdup(mem_ctx, lp_passwordserver());
p = pserver;
while(next_token( &p, desthost, LIST_SEP, sizeof(desthost))) {
NTSTATUS status;
standard_sub_basic(current_user_info.smb_name, current_user_info.domain,
desthost, sizeof(desthost));
strupper_m(desthost);
if(!resolve_name( desthost, &dest_ip, 0x20)) {
DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost));
continue;
}
if (ismyip_v4(dest_ip)) {
DEBUG(1,("Password server loop - disabling password server %s\n",desthost));
continue;
}
/* we use a mutex to prevent two connections at once - when a
Win2k PDC get two connections where one hasn't completed a
session setup yet it will send a TCP reset to the first
connection (tridge) */
if (!grab_server_mutex(desthost)) {
return NULL;
}
status = cli_connect(cli, desthost, &dest_ip);
if (NT_STATUS_IS_OK(status)) {
DEBUG(3,("connected to password server %s\n",desthost));
connected_ok = True;
break;
}
DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
desthost, nt_errstr(status) ));
}
if (!connected_ok) {
release_server_mutex();
DEBUG(0,("password server not available\n"));
cli_shutdown(cli);
return NULL;
}
if (!attempt_netbios_session_request(&cli, global_myname(),
desthost, &dest_ip)) {
release_server_mutex();
DEBUG(1,("password server fails session request\n"));
cli_shutdown(cli);
return NULL;
}
if (strequal(desthost,myhostname())) {
exit_server_cleanly("Password server loop!");
}
DEBUG(3,("got session\n"));
if (!cli_negprot(cli)) {
DEBUG(1,("%s rejected the negprot\n",desthost));
release_server_mutex();
cli_shutdown(cli);
return NULL;
}
if (cli->protocol < PROTOCOL_LANMAN2 ||
!(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
DEBUG(1,("%s isn't in user level security mode\n",desthost));
release_server_mutex();
cli_shutdown(cli);
return NULL;
}
/* Get the first session setup done quickly, to avoid silly
Win2k bugs. (The next connection to the server will kill
this one...
*/
if (!NT_STATUS_IS_OK(cli_session_setup(cli, "", "", 0, "", 0,
""))) {
DEBUG(0,("%s rejected the initial session setup (%s)\n",
desthost, cli_errstr(cli)));
release_server_mutex();
cli_shutdown(cli);
return NULL;
}
release_server_mutex();
DEBUG(3,("password server OK\n"));
return cli;
}
struct server_security_state {
struct cli_state *cli;
};
/****************************************************************************
Send a 'keepalive' packet down the cli pipe.
****************************************************************************/
static bool send_server_keepalive(const struct timeval *now,
void *private_data)
{
struct server_security_state *state = talloc_get_type_abort(
private_data, struct server_security_state);
if (!state->cli || !state->cli->initialised) {
return False;
}
if (send_keepalive(state->cli->fd)) {
return True;
}
DEBUG( 2, ( "send_server_keepalive: password server keepalive "
"failed.\n"));
cli_shutdown(state->cli);
state->cli = NULL;
return False;
}
static int destroy_server_security(struct server_security_state *state)
{
if (state->cli) {
cli_shutdown(state->cli);
}
return 0;
}
static struct server_security_state *make_server_security_state(struct cli_state *cli)
{
struct server_security_state *result;
if (!(result = talloc(NULL, struct server_security_state))) {
DEBUG(0, ("talloc failed\n"));
cli_shutdown(cli);
return NULL;
}
result->cli = cli;
talloc_set_destructor(result, destroy_server_security);
if (lp_keepalive() != 0) {
struct timeval interval;
interval.tv_sec = lp_keepalive();
interval.tv_usec = 0;
if (event_add_idle(smbd_event_context(), result, interval,
"server_security_keepalive",
send_server_keepalive,
result) == NULL) {
DEBUG(0, ("event_add_idle failed\n"));
TALLOC_FREE(result);
return NULL;
}
}
return result;
}
/****************************************************************************
Get the challenge out of a password server.
****************************************************************************/
static DATA_BLOB auth_get_challenge_server(const struct auth_context *auth_context,
void **my_private_data,
TALLOC_CTX *mem_ctx)
{
struct cli_state *cli = server_cryptkey(mem_ctx);
if (cli) {
DEBUG(3,("using password server validation\n"));
if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
/* We can't work with unencrypted password servers
unless 'encrypt passwords = no' */
DEBUG(5,("make_auth_info_server: Server is unencrypted, no challenge available..\n"));
/* However, it is still a perfectly fine connection
to pass that unencrypted password over */
*my_private_data =
(void *)make_server_security_state(cli);
return data_blob_null;
} else if (cli->secblob.length < 8) {
/* We can't do much if we don't get a full challenge */
DEBUG(2,("make_auth_info_server: Didn't receive a full challenge from server\n"));
cli_shutdown(cli);
return data_blob_null;
}
if (!(*my_private_data = (void *)make_server_security_state(cli))) {
return data_blob(NULL,0);
}
/* The return must be allocated on the caller's mem_ctx, as our own will be
destoyed just after the call. */
return data_blob_talloc(auth_context->mem_ctx, cli->secblob.data,8);
} else {
return data_blob_null;
}
}
/****************************************************************************
Check for a valid username and password in security=server mode.
- Validate a password with the password server.
****************************************************************************/
static NTSTATUS check_smbserver_security(const struct auth_context *auth_context,
void *my_private_data,
TALLOC_CTX *mem_ctx,
const auth_usersupplied_info *user_info,
auth_serversupplied_info **server_info)
{
struct cli_state *cli;
static unsigned char badpass[24];
static fstring baduser;
static bool tested_password_server = False;
static bool bad_password_server = False;
NTSTATUS nt_status = NT_STATUS_NOT_IMPLEMENTED;
bool locally_made_cli = False;
cli = (struct cli_state *)my_private_data;
if (cli) {
} else {
cli = server_cryptkey(mem_ctx);
locally_made_cli = True;
}
if (!cli || !cli->initialised) {
DEBUG(1,("password server is not connected (cli not initilised)\n"));
return NT_STATUS_LOGON_FAILURE;
}
if ((cli->sec_mode & NEGOTIATE_SECURITY_CHALLENGE_RESPONSE) == 0) {
if (user_info->encrypted) {
DEBUG(1,("password server %s is plaintext, but we are encrypted. This just can't work :-(\n", cli->desthost));
return NT_STATUS_LOGON_FAILURE;
}
} else {
if (memcmp(cli->secblob.data, auth_context->challenge.data, 8) != 0) {
DEBUG(1,("the challenge that the password server (%s) supplied us is not the one we gave our client. This just can't work :-(\n", cli->desthost));
return NT_STATUS_LOGON_FAILURE;
}
}
if(badpass[0] == 0)
memset(badpass, 0x1f, sizeof(badpass));
if((user_info->nt_resp.length == sizeof(badpass)) &&
!memcmp(badpass, user_info->nt_resp.data, sizeof(badpass))) {
/*
* Very unlikely, our random bad password is the same as the users
* password.
*/
memset(badpass, badpass[0]+1, sizeof(badpass));
}
if(baduser[0] == 0) {
fstrcpy(baduser, INVALID_USER_PREFIX);
fstrcat(baduser, global_myname());
}
/*
* Attempt a session setup with a totally incorrect password.
* If this succeeds with the guest bit *NOT* set then the password
* server is broken and is not correctly setting the guest bit. We
* need to detect this as some versions of NT4.x are broken. JRA.
*/
/* I sure as hell hope that there aren't servers out there that take
* NTLMv2 and have this bug, as we don't test for that...
* - abartlet@samba.org
*/
if ((!tested_password_server) && (lp_paranoid_server_security())) {
if (NT_STATUS_IS_OK(cli_session_setup(cli, baduser,
(char *)badpass,
sizeof(badpass),
(char *)badpass,
sizeof(badpass),
user_info->domain))) {
/*
* We connected to the password server so we
* can say we've tested it.
*/
tested_password_server = True;
if ((SVAL(cli->inbuf,smb_vwv2) & 1) == 0) {
DEBUG(0,("server_validate: password server %s allows users as non-guest \
with a bad password.\n", cli->desthost));
DEBUG(0,("server_validate: This is broken (and insecure) behaviour. Please do not \
use this machine as the password server.\n"));
cli_ulogoff(cli);
/*
* Password server has the bug.
*/
bad_password_server = True;
return NT_STATUS_LOGON_FAILURE;
}
cli_ulogoff(cli);
}
} else {
/*
* We have already tested the password server.
* Fail immediately if it has the bug.
*/
if(bad_password_server) {
DEBUG(0,("server_validate: [1] password server %s allows users as non-guest \
with a bad password.\n", cli->desthost));
DEBUG(0,("server_validate: [1] This is broken (and insecure) behaviour. Please do not \
use this machine as the password server.\n"));
return NT_STATUS_LOGON_FAILURE;
}
}
/*
* Now we know the password server will correctly set the guest bit, or is
* not guest enabled, we can try with the real password.
*/
if (!user_info->encrypted) {
/* Plaintext available */
nt_status = cli_session_setup(
cli, user_info->smb_name,
(char *)user_info->plaintext_password.data,
user_info->plaintext_password.length,
NULL, 0, user_info->domain);
} else {
nt_status = cli_session_setup(
cli, user_info->smb_name,
(char *)user_info->lm_resp.data,
user_info->lm_resp.length,
(char *)user_info->nt_resp.data,
user_info->nt_resp.length,
user_info->domain);
}
if (!NT_STATUS_IS_OK(nt_status)) {
DEBUG(1,("password server %s rejected the password: %s\n",
cli->desthost, nt_errstr(nt_status)));
}
/* if logged in as guest then reject */
if ((SVAL(cli->inbuf,smb_vwv2) & 1) != 0) {
DEBUG(1,("password server %s gave us guest only\n", cli->desthost));
nt_status = NT_STATUS_LOGON_FAILURE;
}
cli_ulogoff(cli);
if (NT_STATUS_IS_OK(nt_status)) {
fstring real_username;
struct passwd *pass;
if ( (pass = smb_getpwnam( NULL, user_info->internal_username,
real_username, True )) != NULL )
{
/* if a real user check pam account restrictions */
/* only really perfomed if "obey pam restriction" is true */
nt_status = smb_pam_accountcheck(pass->pw_name);
if ( !NT_STATUS_IS_OK(nt_status)) {
DEBUG(1, ("PAM account restriction prevents user login\n"));
} else {
nt_status = make_server_info_pw(server_info, pass->pw_name, pass);
}
TALLOC_FREE(pass);
}
else
{
nt_status = NT_STATUS_NO_SUCH_USER;
}
}
if (locally_made_cli) {
cli_shutdown(cli);
}
return(nt_status);
}
static NTSTATUS auth_init_smbserver(struct auth_context *auth_context, const char* param, auth_methods **auth_method)
{
if (!make_auth_methods(auth_context, auth_method)) {
return NT_STATUS_NO_MEMORY;
}
(*auth_method)->name = "smbserver";
(*auth_method)->auth = check_smbserver_security;
(*auth_method)->get_chal = auth_get_challenge_server;
return NT_STATUS_OK;
}
NTSTATUS auth_server_init(void)
{
return smb_register_auth(AUTH_INTERFACE_VERSION, "smbserver", auth_init_smbserver);
}
|