/* 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; char *desthost = NULL; struct sockaddr_storage dest_ss; const char *p; char *pserver = NULL; 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_talloc(mem_ctx, &p, &desthost, LIST_SEP)) { NTSTATUS status; desthost = talloc_sub_basic(mem_ctx, current_user_info.smb_name, current_user_info.domain, desthost); if (!desthost) { return NULL; } strupper_m(desthost); if(!resolve_name( desthost, &dest_ss, 0x20)) { DEBUG(1,("server_cryptkey: Can't resolve address for %s\n",desthost)); continue; } if (ismyaddr(&dest_ss)) { 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)) { cli_shutdown(cli); return NULL; } status = cli_connect(cli, desthost, &dest_ss); 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) )); release_server_mutex(); } if (!connected_ok) { DEBUG(0,("password server not available\n")); cli_shutdown(cli); return NULL; } if (!attempt_netbios_session_request(&cli, global_myname(), desthost, &dest_ss)) { 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 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; } } /* * 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())) { unsigned char badpass[24]; char *baduser = NULL; 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)); } baduser = talloc_asprintf(mem_ctx, "%s%s", INVALID_USER_PREFIX, global_myname()); if (!baduser) { return NT_STATUS_NO_MEMORY; } 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); }