database.c

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/* -------------------------------------------------------------------------
 *
 * contrib/sepgsql/database.c
 *
 * Routines corresponding to database objects
 *
 * Copyright (c) 2010-2021, PostgreSQL Global Development Group
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/dependency.h"
#include "catalog/pg_database.h"
#include "commands/dbcommands.h"
#include "commands/seclabel.h"
#include "sepgsql.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/snapmgr.h"

/*
 * sepgsql_database_post_create
 *
 * This routine assigns a default security label on a newly defined
 * database, and check permission needed for its creation.
 */
void
sepgsql_database_post_create(Oid databaseId, const char *dtemplate)
{
    Relation    rel;
    ScanKeyData skey;
    SysScanDesc sscan;
    HeapTuple   tuple;
    char       *tcontext;
    char       *ncontext;
    ObjectAddress object;
    Form_pg_database datForm;
    StringInfoData audit_name;

    /*
     * Oid of the source database is not saved in pg_database catalog, so we
     * collect its identifier using contextual information. If NULL, its
     * default is "template1" according to createdb().
     */
    if (!dtemplate)
        dtemplate = "template1";

    object.classId = DatabaseRelationId;
    object.objectId = get_database_oid(dtemplate, false);
    object.objectSubId = 0;

    tcontext = sepgsql_get_label(object.classId,
                                 object.objectId,
                                 object.objectSubId);

    /*
     * check db_database:{getattr} permission
     */
    initStringInfo(&audit_name);
    appendStringInfoString(&audit_name, quote_identifier(dtemplate));
    sepgsql_avc_check_perms_label(tcontext,
                                  SEPG_CLASS_DB_DATABASE,
                                  SEPG_DB_DATABASE__GETATTR,
                                  audit_name.data,
                                  true);

    /*
     * Compute a default security label of the newly created database based on
     * a pair of security label of client and source database.
     *
     * XXX - upcoming version of libselinux supports to take object name to
     * handle special treatment on default security label.
     */
    rel = table_open(DatabaseRelationId, AccessShareLock);

    ScanKeyInit(&skey,
                Anum_pg_database_oid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(databaseId));

    sscan = systable_beginscan(rel, DatabaseOidIndexId, true,
                               SnapshotSelf, 1, &skey);
    tuple = systable_getnext(sscan);
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "could not find tuple for database %u", databaseId);

    datForm = (Form_pg_database) GETSTRUCT(tuple);

    ncontext = sepgsql_compute_create(sepgsql_get_client_label(),
                                      tcontext,
                                      SEPG_CLASS_DB_DATABASE,
                                      NameStr(datForm->datname));

    /*
     * check db_database:{create} permission
     */
    resetStringInfo(&audit_name);
    appendStringInfoString(&audit_name,
                           quote_identifier(NameStr(datForm->datname)));
    sepgsql_avc_check_perms_label(ncontext,
                                  SEPG_CLASS_DB_DATABASE,
                                  SEPG_DB_DATABASE__CREATE,
                                  audit_name.data,
                                  true);

    systable_endscan(sscan);
    table_close(rel, AccessShareLock);

    /*
     * Assign the default security label on the new database
     */
    object.classId = DatabaseRelationId;
    object.objectId = databaseId;
    object.objectSubId = 0;

    SetSecurityLabel(&object, SEPGSQL_LABEL_TAG, ncontext);

    pfree(ncontext);
    pfree(tcontext);
}

/*
 * sepgsql_database_drop
 *
 * It checks privileges to drop the supplied database
 */
void
sepgsql_database_drop(Oid databaseId)
{
    ObjectAddress object;
    char       *audit_name;

    /*
     * check db_database:{drop} permission
     */
    object.classId = DatabaseRelationId;
    object.objectId = databaseId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    sepgsql_avc_check_perms(&object,
                            SEPG_CLASS_DB_DATABASE,
                            SEPG_DB_DATABASE__DROP,
                            audit_name,
                            true);
    pfree(audit_name);
}

/*
 * sepgsql_database_post_alter
 *
 * It checks privileges to alter the supplied database
 */
void
sepgsql_database_setattr(Oid databaseId)
{
    ObjectAddress object;
    char       *audit_name;

    /*
     * check db_database:{setattr} permission
     */
    object.classId = DatabaseRelationId;
    object.objectId = databaseId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    sepgsql_avc_check_perms(&object,
                            SEPG_CLASS_DB_DATABASE,
                            SEPG_DB_DATABASE__SETATTR,
                            audit_name,
                            true);
    pfree(audit_name);
}

/*
 * sepgsql_database_relabel
 *
 * It checks privileges to relabel the supplied database with the `seclabel'
 */
void
sepgsql_database_relabel(Oid databaseId, const char *seclabel)
{
    ObjectAddress object;
    char       *audit_name;

    object.classId = DatabaseRelationId;
    object.objectId = databaseId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    /*
     * check db_database:{setattr relabelfrom} permission
     */
    sepgsql_avc_check_perms(&object,
                            SEPG_CLASS_DB_DATABASE,
                            SEPG_DB_DATABASE__SETATTR |
                            SEPG_DB_DATABASE__RELABELFROM,
                            audit_name,
                            true);

    /*
     * check db_database:{relabelto} permission
     */
    sepgsql_avc_check_perms_label(seclabel,
                                  SEPG_CLASS_DB_DATABASE,
                                  SEPG_DB_DATABASE__RELABELTO,
                                  audit_name,
                                  true);
    pfree(audit_name);
}