source: vendor/current/source3/auth/auth_samba4.c

/*
   Unix SMB/CIFS implementation.
   Authenticate against Samba4's auth subsystem
   Copyright (C) Volker Lendecke 2008
   Copyright (C) Andrew Bartlett 2010

   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"
#include "source3/include/auth.h"
#include "source3/include/messages.h"
#include "source4/auth/auth.h"
#include "auth/auth_sam_reply.h"
#include "param/param.h"
#include "source4/lib/events/events.h"
#include "source4/lib/messaging/messaging.h"
#include "auth/gensec/gensec.h"
#include "auth/credentials/credentials.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_AUTH

static NTSTATUS make_auth4_context_s4(const struct auth_context *auth_context,
                                      TALLOC_CTX *mem_ctx,
                                      struct auth4_context **auth4_context);

static struct idr_context *task_id_tree;

static int free_task_id(struct server_id *server_id)
{
        idr_remove(task_id_tree, server_id->task_id);
        return 0;
}

/* Return a server_id with a unique task_id element.  Free the
 * returned pointer to de-allocate the task_id via a talloc destructor
 * (ie, use talloc_free()) */
static struct server_id *new_server_id_task(TALLOC_CTX *mem_ctx)
{
        struct messaging_context *msg_ctx;
        struct server_id *server_id;
        int task_id;
        if (!task_id_tree) {
                task_id_tree = idr_init(NULL);
                if (!task_id_tree) {
                        return NULL;
                }
        }

        msg_ctx = server_messaging_context();
        if (msg_ctx == NULL) {
                return NULL;
        }

        server_id = talloc(mem_ctx, struct server_id);

        if (!server_id) {
                return NULL;
        }
        *server_id = messaging_server_id(msg_ctx);

        /* 0 is the default server_id, so we need to start with 1 */
        task_id = idr_get_new_above(task_id_tree, server_id, 1, INT32_MAX);

        if (task_id == -1) {
                talloc_free(server_id);
                return NULL;
        }

        talloc_set_destructor(server_id, free_task_id);
        server_id->task_id = task_id;
        return server_id;
}

/*
 * This module is not an ordinary authentication module.  It is really
 * a way to redirect the whole authentication and authorization stack
 * to use the source4 auth code, not a way to just handle NTLM
 * authentication.
 *
 * See the comments above each function for how that hook changes the
 * behaviour.
 */

/* 
 * This hook is currently used by winbindd only, as all other NTLM
 * logins go via the hooks provided by make_auth4_context_s4() below.
 *
 * This is only left in case we find a way that it might become useful
 * in future.  Importantly, this routine returns the information
 * needed for a NETLOGON SamLogon, not what is needed to establish a
 * session.
 *
 * We expect we may use this hook in the source3/ winbind when this
 * services the AD DC.  It is tested via pdbtest.
 */

static NTSTATUS check_samba4_security(const struct auth_context *auth_context,
                                      void *my_private_data,
                                      TALLOC_CTX *mem_ctx,
                                      const struct auth_usersupplied_info *user_info,
                                      struct auth_serversupplied_info **server_info)
{
        TALLOC_CTX *frame = talloc_stackframe();
        struct netr_SamInfo3 *info3 = NULL;
        NTSTATUS nt_status;
        struct auth_user_info_dc *user_info_dc;
        struct auth4_context *auth4_context;

        nt_status = make_auth4_context_s4(auth_context, mem_ctx, &auth4_context);
        if (!NT_STATUS_IS_OK(nt_status)) {
                TALLOC_FREE(frame);
                goto done;
        }
                
        nt_status = auth_context_set_challenge(auth4_context, auth_context->challenge.data, "auth_samba4");
        if (!NT_STATUS_IS_OK(nt_status)) {
                TALLOC_FREE(auth4_context);
                TALLOC_FREE(frame);
                return nt_status;
        }

        nt_status = auth_check_password(auth4_context, auth4_context, user_info, &user_info_dc);
        if (!NT_STATUS_IS_OK(nt_status)) {
                TALLOC_FREE(auth4_context);
                TALLOC_FREE(frame);
                return nt_status;
        }
        
        nt_status = auth_convert_user_info_dc_saminfo3(mem_ctx,
                                                       user_info_dc,
                                                       &info3);
        if (NT_STATUS_IS_OK(nt_status)) {
                /* We need the strings from the server_info to be valid as long as the info3 is around */
                talloc_steal(info3, user_info_dc);
        }
        talloc_free(auth4_context);

        if (!NT_STATUS_IS_OK(nt_status)) {
                goto done;
        }

        if (user_info->flags & USER_INFO_INFO3_AND_NO_AUTHZ) {
                *server_info = make_server_info(mem_ctx);
                if (*server_info == NULL) {
                        nt_status = NT_STATUS_NO_MEMORY;
                        goto done;
                }
                (*server_info)->info3 = talloc_steal(*server_info, info3);

        } else {
                nt_status = make_server_info_info3(mem_ctx, user_info->client.account_name,
                                                   user_info->mapped.domain_name, server_info,
                                                   info3);
                if (!NT_STATUS_IS_OK(nt_status)) {
                        DEBUG(10, ("make_server_info_info3 failed: %s\n",
                                   nt_errstr(nt_status)));
                        goto done;
                }
        }

        nt_status = NT_STATUS_OK;

 done:
        TALLOC_FREE(frame);
        return nt_status;
}

/*
 * Hook to allow the source4 set of GENSEC modules to handle
 * blob-based authentication mechanisms, without directly linking the
 * mechanism code.
 *
 * This may eventually go away, when the GSSAPI acceptors are merged,
 * when we will just rely on the make_auth4_context_s4 hook instead.
 *
 * Even for NTLMSSP, which has a common module, significant parts of
 * the behaviour are overridden here, because it uses the source4 NTLM
 * stack and the source4 mapping between the PAC/SamLogon response and
 * the local token.
 *
 * It is important to override all this to ensure that the exact same
 * token is generated and used in the SMB and LDAP servers, for NTLM
 * and for Kerberos.
 */
static NTSTATUS prepare_gensec(const struct auth_context *auth_context,
                               TALLOC_CTX *mem_ctx,
                               struct gensec_security **gensec_context)
{
        NTSTATUS status;
        struct loadparm_context *lp_ctx;
        struct tevent_context *event_ctx;
        TALLOC_CTX *frame = talloc_stackframe();
        struct gensec_security *gensec_ctx;
        struct imessaging_context *msg_ctx;
        struct cli_credentials *server_credentials;
        struct server_id *server_id;

        lp_ctx = loadparm_init_s3(frame, loadparm_s3_helpers());
        if (lp_ctx == NULL) {
                DEBUG(1, ("loadparm_init_s3 failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }
        event_ctx = s4_event_context_init(frame);
        if (event_ctx == NULL) {
                DEBUG(1, ("s4_event_context_init failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        server_id = new_server_id_task(frame);
        if (server_id == NULL) {
                DEBUG(1, ("new_server_id_task failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        msg_ctx = imessaging_init(frame,
                                  lp_ctx,
                                  *server_id,
                                  event_ctx, true);
        if (msg_ctx == NULL) {
                DEBUG(1, ("imessaging_init failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        talloc_reparent(frame, msg_ctx, server_id);

        server_credentials
                = cli_credentials_init(frame);
        if (!server_credentials) {
                DEBUG(1, ("Failed to init server credentials"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        cli_credentials_set_conf(server_credentials, lp_ctx);
        status = cli_credentials_set_machine_account(server_credentials, lp_ctx);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("Failed to obtain server credentials, perhaps a standalone server?: %s\n", nt_errstr(status)));
                TALLOC_FREE(frame);
                return status;
        }

        status = samba_server_gensec_start(mem_ctx,
                                           event_ctx, msg_ctx,
                                           lp_ctx, server_credentials, "cifs",
                                           &gensec_ctx);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status)));
                TALLOC_FREE(frame);
                return status;
        }

        talloc_reparent(frame, gensec_ctx, msg_ctx);
        talloc_reparent(frame, gensec_ctx, event_ctx);
        talloc_reparent(frame, gensec_ctx, lp_ctx);
        talloc_reparent(frame, gensec_ctx, server_credentials);

        gensec_want_feature(gensec_ctx, GENSEC_FEATURE_SESSION_KEY);
        gensec_want_feature(gensec_ctx, GENSEC_FEATURE_UNIX_TOKEN);

        *gensec_context = gensec_ctx;
        TALLOC_FREE(frame);
        return status;
}

/*
 * Hook to allow handling of NTLM authentication for AD operation
 * without directly linking the s4 auth stack
 *
 * This ensures we use the source4 authentication stack, as well as
 * the authorization stack to create the user's token.  This ensures
 * consistency between NTLM logins and NTLMSSP logins, as NTLMSSP is
 * handled by the hook above.
 */
static NTSTATUS make_auth4_context_s4(const struct auth_context *auth_context,
                                      TALLOC_CTX *mem_ctx,
                                      struct auth4_context **auth4_context)
{
        NTSTATUS status;
        struct loadparm_context *lp_ctx;
        struct tevent_context *event_ctx;
        TALLOC_CTX *frame = talloc_stackframe();
        struct imessaging_context *msg_ctx;
        struct server_id *server_id;

        lp_ctx = loadparm_init_s3(frame, loadparm_s3_helpers());
        if (lp_ctx == NULL) {
                DEBUG(1, ("loadparm_init_s3 failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }
        event_ctx = s4_event_context_init(frame);
        if (event_ctx == NULL) {
                DEBUG(1, ("s4_event_context_init failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        server_id = new_server_id_task(frame);
        if (server_id == NULL) {
                DEBUG(1, ("new_server_id_task failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }

        msg_ctx = imessaging_init(frame,
                                  lp_ctx,
                                  *server_id,
                                  event_ctx, true);
        if (msg_ctx == NULL) {
                DEBUG(1, ("imessaging_init failed\n"));
                TALLOC_FREE(frame);
                return NT_STATUS_INVALID_SERVER_STATE;
        }
        talloc_reparent(frame, msg_ctx, server_id);

        /* Allow forcing a specific auth4 module */
        if (!auth_context->forced_samba4_methods) {
                status = auth_context_create(mem_ctx,
                                             event_ctx,
                                             msg_ctx,
                                             lp_ctx,
                                             auth4_context);
        } else {
                const char * const *forced_auth_methods = (const char * const *)str_list_make(mem_ctx, auth_context->forced_samba4_methods, NULL);
                status = auth_context_create_methods(mem_ctx, forced_auth_methods, event_ctx, msg_ctx, lp_ctx, NULL, auth4_context);
        }
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(1, ("Failed to start auth server code: %s\n", nt_errstr(status)));
                TALLOC_FREE(frame);
                return status;
        }

        talloc_reparent(frame, *auth4_context, msg_ctx);
        talloc_reparent(frame, *auth4_context, event_ctx);
        talloc_reparent(frame, *auth4_context, lp_ctx);

        TALLOC_FREE(frame);
        return status;
}

/* module initialisation */
static NTSTATUS auth_init_samba4(struct auth_context *auth_context,
                                    const char *param,
                                    auth_methods **auth_method)
{
        struct auth_methods *result;

        gensec_init();

        result = talloc_zero(auth_context, struct auth_methods);
        if (result == NULL) {
                return NT_STATUS_NO_MEMORY;
        }
        result->name = "samba4";
        result->auth = check_samba4_security;
        result->prepare_gensec = prepare_gensec;
        result->make_auth4_context = make_auth4_context_s4;
        result->flags = AUTH_METHOD_LOCAL_SAM;

        if (param && *param) {
                auth_context->forced_samba4_methods = talloc_strdup(result, param);
                if (!auth_context->forced_samba4_methods) {
                        return NT_STATUS_NO_MEMORY;
                }
        }

        *auth_method = result;
        return NT_STATUS_OK;
}

NTSTATUS auth_samba4_init(void);
NTSTATUS auth_samba4_init(void)
{
        smb_register_auth(AUTH_INTERFACE_VERSION, "samba4",
                          auth_init_samba4);
        return NT_STATUS_OK;
}