source: vendor/3.6.9/source3/passdb/machine_sid.c

/* 
   Unix SMB/CIFS implementation.
   Password and authentication handling
   Copyright (C) Jeremy Allison                 1996-2002
   Copyright (C) Andrew Tridgell                2002
   Copyright (C) Gerald (Jerry) Carter          2000
   Copyright (C) Stefan (metze) Metzmacher      2002

   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 "passdb.h"
#include "secrets.h"
#include "dbwrap.h"
#include "../libcli/security/security.h"

/* NOTE! the global_sam_sid is the SID of our local SAM. This is only
   equal to the domain SID when we are a DC, otherwise its our
   workstation SID */
static struct dom_sid *global_sam_sid=NULL;

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_PASSDB

/****************************************************************************
 Read a SID from a file. This is for compatibility with the old MACHINE.SID
 style of SID storage
****************************************************************************/

static bool read_sid_from_file(const char *fname, struct dom_sid *sid)
{
        char **lines;
        int numlines;
        bool ret;

        lines = file_lines_load(fname, &numlines,0, NULL);

        if (!lines || numlines < 1) {
                TALLOC_FREE(lines);
                return False;
        }

        ret = string_to_sid(sid, lines[0]);
        TALLOC_FREE(lines);
        return ret;
}

/*
  generate a random sid - used to build our own sid if we don't have one
*/
static void generate_random_sid(struct dom_sid *sid)
{
        int i;
        uchar raw_sid_data[12];

        ZERO_STRUCTP(sid);

        sid->sid_rev_num = 1;
        sid->id_auth[5] = 5;
        sid->num_auths = 0;
        sid->sub_auths[sid->num_auths++] = 21;

        generate_random_buffer(raw_sid_data, 12);
        for (i = 0; i < 3; i++)
                sid->sub_auths[sid->num_auths++] = IVAL(raw_sid_data, i*4);
}

/****************************************************************************
 Generate the global machine sid.
****************************************************************************/

static struct dom_sid *pdb_generate_sam_sid(void)
{
        struct dom_sid domain_sid;
        char *fname = NULL;
        struct dom_sid *sam_sid;

        if(!(sam_sid=SMB_MALLOC_P(struct dom_sid)))
                return NULL;

        if ( IS_DC ) {
                if (secrets_fetch_domain_sid(lp_workgroup(), &domain_sid)) {
                        sid_copy(sam_sid, &domain_sid);
                        return sam_sid;
                }
        }

        if (secrets_fetch_domain_sid(global_myname(), sam_sid)) {

                /* We got our sid. If not a pdc/bdc, we're done. */
                if ( !IS_DC )
                        return sam_sid;

                if (!secrets_fetch_domain_sid(lp_workgroup(), &domain_sid)) {

                        /* No domain sid and we're a pdc/bdc. Store it */

                        if (!secrets_store_domain_sid(lp_workgroup(), sam_sid)) {
                                DEBUG(0,("pdb_generate_sam_sid: Can't store domain SID as a pdc/bdc.\n"));
                                SAFE_FREE(sam_sid);
                                return NULL;
                        }
                        return sam_sid;
                }

                if (!dom_sid_equal(&domain_sid, sam_sid)) {

                        /* Domain name sid doesn't match global sam sid. Re-store domain sid as 'local' sid. */

                        DEBUG(0,("pdb_generate_sam_sid: Mismatched SIDs as a pdc/bdc.\n"));
                        if (!secrets_store_domain_sid(global_myname(), &domain_sid)) {
                                DEBUG(0,("pdb_generate_sam_sid: Can't re-store domain SID for local sid as PDC/BDC.\n"));
                                SAFE_FREE(sam_sid);
                                return NULL;
                        }
                        return sam_sid;
                }

                return sam_sid;
        }

        /* check for an old MACHINE.SID file for backwards compatibility */
        if (asprintf(&fname, "%s/MACHINE.SID", lp_private_dir()) == -1) {
                SAFE_FREE(sam_sid);
                return NULL;
        }

        if (read_sid_from_file(fname, sam_sid)) {
                /* remember it for future reference and unlink the old MACHINE.SID */
                if (!secrets_store_domain_sid(global_myname(), sam_sid)) {
                        DEBUG(0,("pdb_generate_sam_sid: Failed to store SID from file.\n"));
                        SAFE_FREE(fname);
                        SAFE_FREE(sam_sid);
                        return NULL;
                }
                unlink(fname);
                if ( !IS_DC ) {
                        if (!secrets_store_domain_sid(lp_workgroup(), sam_sid)) {
                                DEBUG(0,("pdb_generate_sam_sid: Failed to store domain SID from file.\n"));
                                SAFE_FREE(fname);
                                SAFE_FREE(sam_sid);
                                return NULL;
                        }
                }

                /* Stored the old sid from MACHINE.SID successfully.*/
                SAFE_FREE(fname);
                return sam_sid;
        }

        SAFE_FREE(fname);

        /* we don't have the SID in secrets.tdb, we will need to
           generate one and save it */
        generate_random_sid(sam_sid);

        if (!secrets_store_domain_sid(global_myname(), sam_sid)) {
                DEBUG(0,("pdb_generate_sam_sid: Failed to store generated machine SID.\n"));
                SAFE_FREE(sam_sid);
                return NULL;
        }
        if ( IS_DC ) {
                if (!secrets_store_domain_sid(lp_workgroup(), sam_sid)) {
                        DEBUG(0,("pdb_generate_sam_sid: Failed to store generated domain SID.\n"));
                        SAFE_FREE(sam_sid);
                        return NULL;
                }
        }

        return sam_sid;
}   

/* return our global_sam_sid */
struct dom_sid *get_global_sam_sid(void)
{
        struct db_context *db;

        if (global_sam_sid != NULL)
                return global_sam_sid;

        /*
         * memory for global_sam_sid is allocated in
         * pdb_generate_sam_sid() as needed
         *
         * Note: this is garded by a transaction
         *       to prevent races on startup which
         *       can happen with some dbwrap backends
         */

        db = secrets_db_ctx();
        if (!db) {
                smb_panic("could not open secrets db");
        }

        if (db->transaction_start(db) != 0) {
                smb_panic("could not start transaction on secrets db");
        }

        if (!(global_sam_sid = pdb_generate_sam_sid())) {
                db->transaction_cancel(db);
                smb_panic("could not generate a machine SID");
        }

        if (db->transaction_commit(db) != 0) {
                smb_panic("could not start commit secrets db");
        }

        return global_sam_sid;
}

/** 
 * Force get_global_sam_sid to requery the backends 
 */
void reset_global_sam_sid(void) 
{
        SAFE_FREE(global_sam_sid);
}

/*****************************************************************
 Check if the SID is our domain SID (S-1-5-21-x-y-z).
*****************************************************************/  

bool sid_check_is_domain(const struct dom_sid *sid)
{
        return dom_sid_equal(sid, get_global_sam_sid());
}

/*****************************************************************
 Check if the SID is our domain SID (S-1-5-21-x-y-z).
*****************************************************************/  

bool sid_check_is_in_our_domain(const struct dom_sid *sid)
{
        struct dom_sid dom_sid;

        sid_copy(&dom_sid, sid);
        sid_split_rid(&dom_sid, NULL);
        return sid_check_is_domain(&dom_sid);
}