schema.c

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/* -------------------------------------------------------------------------
 *
 * contrib/sepgsql/schema.c
 *
 * Routines corresponding to schema objects
 *
 * Copyright (c) 2010-2020, 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/indexing.h"
#include "catalog/pg_database.h"
#include "catalog/pg_namespace.h"
#include "commands/seclabel.h"
#include "lib/stringinfo.h"
#include "miscadmin.h"
#include "sepgsql.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/snapmgr.h"

/*
 * sepgsql_schema_post_create
 *
 * This routine assigns a default security label on a newly defined
 * schema.
 */
void
sepgsql_schema_post_create(Oid namespaceId)
{
    Relation    rel;
    ScanKeyData skey;
    SysScanDesc sscan;
    HeapTuple   tuple;
    char       *tcontext;
    char       *ncontext;
    const char *nsp_name;
    ObjectAddress object;
    Form_pg_namespace nspForm;
    StringInfoData audit_name;

    /*
     * Compute a default security label when we create a new schema object
     * under the working database.
     *
     * XXX - upcoming version of libselinux supports to take object name to
     * handle special treatment on default security label; such as special
     * label on "pg_temp" schema.
     */
    rel = table_open(NamespaceRelationId, AccessShareLock);

    ScanKeyInit(&skey,
                Anum_pg_namespace_oid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(namespaceId));

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

    nspForm = (Form_pg_namespace) GETSTRUCT(tuple);
    nsp_name = NameStr(nspForm->nspname);
    if (strncmp(nsp_name, "pg_temp_", 8) == 0)
        nsp_name = "pg_temp";
    else if (strncmp(nsp_name, "pg_toast_temp_", 14) == 0)
        nsp_name = "pg_toast_temp";

    tcontext = sepgsql_get_label(DatabaseRelationId, MyDatabaseId, 0);
    ncontext = sepgsql_compute_create(sepgsql_get_client_label(),
                                      tcontext,
                                      SEPG_CLASS_DB_SCHEMA,
                                      nsp_name);

    /*
     * check db_schema:{create}
     */
    initStringInfo(&audit_name);
    appendStringInfo(&audit_name, "%s", quote_identifier(nsp_name));
    sepgsql_avc_check_perms_label(ncontext,
                                  SEPG_CLASS_DB_SCHEMA,
                                  SEPG_DB_SCHEMA__CREATE,
                                  audit_name.data,
                                  true);
    systable_endscan(sscan);
    table_close(rel, AccessShareLock);

    /*
     * Assign the default security label on a new procedure
     */
    object.classId = NamespaceRelationId;
    object.objectId = namespaceId;
    object.objectSubId = 0;
    SetSecurityLabel(&object, SEPGSQL_LABEL_TAG, ncontext);

    pfree(ncontext);
    pfree(tcontext);
}

/*
 * sepgsql_schema_drop
 *
 * It checks privileges to drop the supplied schema object.
 */
void
sepgsql_schema_drop(Oid namespaceId)
{
    ObjectAddress object;
    char       *audit_name;

    /*
     * check db_schema:{drop} permission
     */
    object.classId = NamespaceRelationId;
    object.objectId = namespaceId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    sepgsql_avc_check_perms(&object,
                            SEPG_CLASS_DB_SCHEMA,
                            SEPG_DB_SCHEMA__DROP,
                            audit_name,
                            true);
    pfree(audit_name);
}

/*
 * sepgsql_schema_relabel
 *
 * It checks privileges to relabel the supplied schema
 * by the `seclabel'.
 */
void
sepgsql_schema_relabel(Oid namespaceId, const char *seclabel)
{
    ObjectAddress object;
    char       *audit_name;

    object.classId = NamespaceRelationId;
    object.objectId = namespaceId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    /*
     * check db_schema:{setattr relabelfrom} permission
     */
    sepgsql_avc_check_perms(&object,
                            SEPG_CLASS_DB_SCHEMA,
                            SEPG_DB_SCHEMA__SETATTR |
                            SEPG_DB_SCHEMA__RELABELFROM,
                            audit_name,
                            true);

    /*
     * check db_schema:{relabelto} permission
     */
    sepgsql_avc_check_perms_label(seclabel,
                                  SEPG_CLASS_DB_SCHEMA,
                                  SEPG_DB_SCHEMA__RELABELTO,
                                  audit_name,
                                  true);
    pfree(audit_name);
}

/*
 * sepgsql_schema_check_perms
 *
 * utility routine to check db_schema:{xxx} permissions
 */
static bool
check_schema_perms(Oid namespaceId, uint32 required, bool abort_on_violation)
{
    ObjectAddress object;
    char       *audit_name;
    bool        result;

    object.classId = NamespaceRelationId;
    object.objectId = namespaceId;
    object.objectSubId = 0;
    audit_name = getObjectIdentity(&object, false);

    result = sepgsql_avc_check_perms(&object,
                                     SEPG_CLASS_DB_SCHEMA,
                                     required,
                                     audit_name,
                                     abort_on_violation);
    pfree(audit_name);

    return result;
}

/* db_schema:{setattr} permission */
void
sepgsql_schema_setattr(Oid namespaceId)
{
    check_schema_perms(namespaceId, SEPG_DB_SCHEMA__SETATTR, true);
}

/* db_schema:{search} permission */
bool
sepgsql_schema_search(Oid namespaceId, bool abort_on_violation)
{
    return check_schema_perms(namespaceId,
                              SEPG_DB_SCHEMA__SEARCH,
                              abort_on_violation);
}

void
sepgsql_schema_add_name(Oid namespaceId)
{
    check_schema_perms(namespaceId, SEPG_DB_SCHEMA__ADD_NAME, true);
}

void
sepgsql_schema_remove_name(Oid namespaceId)
{
    check_schema_perms(namespaceId, SEPG_DB_SCHEMA__REMOVE_NAME, true);
}

void
sepgsql_schema_rename(Oid namespaceId)
{
    check_schema_perms(namespaceId,
                       SEPG_DB_SCHEMA__ADD_NAME |
                       SEPG_DB_SCHEMA__REMOVE_NAME,
                       true);
}