test_oat_hooks.c

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/*--------------------------------------------------------------------------
 *
 * test_oat_hooks.c
 *      Code for testing mandatory access control (MAC) using object access hooks.
 *
 * Copyright (c) 2015-2023, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/test/modules/test_oat_hooks/test_oat_hooks.c
 *
 * -------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/parallel.h"
#include "catalog/dependency.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_proc.h"
#include "executor/executor.h"
#include "fmgr.h"
#include "miscadmin.h"
#include "tcop/utility.h"
 
PG_MODULE_MAGIC;
 
/*
 * GUCs controlling which operations to deny
 */
static bool REGRESS_deny_set_variable = false;
static bool REGRESS_deny_alter_system = false;
static bool REGRESS_deny_object_access = false;
static bool REGRESS_deny_exec_perms = false;
static bool REGRESS_deny_utility_commands = false;
static bool REGRESS_audit = false;
 
/*
 * GUCs for testing privileges on USERSET and SUSET variables,
 * with and without privileges granted prior to module load.
 */
static bool REGRESS_userset_variable1 = false;
static bool REGRESS_userset_variable2 = false;
static bool REGRESS_suset_variable1 = false;
static bool REGRESS_suset_variable2 = false;
 
/* Saved hook values */
static object_access_hook_type next_object_access_hook = NULL;
static object_access_hook_type_str next_object_access_hook_str = NULL;
static ExecutorCheckPerms_hook_type next_exec_check_perms_hook = NULL;
static ProcessUtility_hook_type next_ProcessUtility_hook = NULL;
 
/* Test Object Access Type Hook hooks */
static void REGRESS_object_access_hook_str(ObjectAccessType access,
                                           Oid classId, const char *objName,
                                           int subId, void *arg);
static void REGRESS_object_access_hook(ObjectAccessType access, Oid classId,
                                       Oid objectId, int subId, void *arg);
static bool REGRESS_exec_check_perms(List *rangeTabls, List *rteperminfos, bool do_abort);
static void REGRESS_utility_command(PlannedStmt *pstmt,
                                    const char *queryString, bool readOnlyTree,
                                    ProcessUtilityContext context,
                                    ParamListInfo params,
                                    QueryEnvironment *queryEnv,
                                    DestReceiver *dest, QueryCompletion *qc);
 
/* Helper functions */
static char *accesstype_to_string(ObjectAccessType access, int subId);
static char *accesstype_arg_to_string(ObjectAccessType access, void *arg);
 
 
/*
 * Module load callback
 */
void
_PG_init(void)
{
    /*
     * test_oat_hooks.deny_set_variable = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.deny_set_variable",
                             "Deny non-superuser set permissions",
                             NULL,
                             &REGRESS_deny_set_variable,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.deny_alter_system = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.deny_alter_system",
                             "Deny non-superuser alter system set permissions",
                             NULL,
                             &REGRESS_deny_alter_system,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.deny_object_access = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.deny_object_access",
                             "Deny non-superuser object access permissions",
                             NULL,
                             &REGRESS_deny_object_access,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.deny_exec_perms = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.deny_exec_perms",
                             "Deny non-superuser exec permissions",
                             NULL,
                             &REGRESS_deny_exec_perms,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.deny_utility_commands = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.deny_utility_commands",
                             "Deny non-superuser utility commands",
                             NULL,
                             &REGRESS_deny_utility_commands,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.audit = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.audit",
                             "Turn on/off debug audit messages",
                             NULL,
                             &REGRESS_audit,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.user_var{1,2} = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.user_var1",
                             "Dummy parameter settable by public",
                             NULL,
                             &REGRESS_userset_variable1,
                             false,
                             PGC_USERSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    DefineCustomBoolVariable("test_oat_hooks.user_var2",
                             "Dummy parameter settable by public",
                             NULL,
                             &REGRESS_userset_variable2,
                             false,
                             PGC_USERSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    /*
     * test_oat_hooks.super_var{1,2} = (on|off)
     */
    DefineCustomBoolVariable("test_oat_hooks.super_var1",
                             "Dummy parameter settable by superuser",
                             NULL,
                             &REGRESS_suset_variable1,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    DefineCustomBoolVariable("test_oat_hooks.super_var2",
                             "Dummy parameter settable by superuser",
                             NULL,
                             &REGRESS_suset_variable2,
                             false,
                             PGC_SUSET,
                             GUC_NOT_IN_SAMPLE,
                             NULL,
                             NULL,
                             NULL);
 
    MarkGUCPrefixReserved("test_oat_hooks");
 
    /* Object access hook */
    next_object_access_hook = object_access_hook;
    object_access_hook = REGRESS_object_access_hook;
 
    /* Object access hook str */
    next_object_access_hook_str = object_access_hook_str;
    object_access_hook_str = REGRESS_object_access_hook_str;
 
    /* DML permission check */
    next_exec_check_perms_hook = ExecutorCheckPerms_hook;
    ExecutorCheckPerms_hook = REGRESS_exec_check_perms;
 
    /* ProcessUtility hook */
    next_ProcessUtility_hook = ProcessUtility_hook;
    ProcessUtility_hook = REGRESS_utility_command;
}
 
static void
emit_audit_message(const char *type, const char *hook, char *action, char *objName)
{
    /*
     * Ensure that audit messages are not duplicated by only emitting them
     * from a leader process, not a worker process. This makes the test
     * results deterministic even if run with debug_parallel_query = regress.
     */
    if (REGRESS_audit && !IsParallelWorker())
    {
        const char *who = superuser_arg(GetUserId()) ? "superuser" : "non-superuser";
 
        if (objName)
            ereport(NOTICE,
                    (errcode(ERRCODE_INTERNAL_ERROR),
                     errmsg("in %s: %s %s %s [%s]", hook, who, type, action, objName)));
        else
            ereport(NOTICE,
                    (errcode(ERRCODE_INTERNAL_ERROR),
                     errmsg("in %s: %s %s %s", hook, who, type, action)));
    }
 
    if (action)
        pfree(action);
    if (objName)
        pfree(objName);
}
 
static void
audit_attempt(const char *hook, char *action, char *objName)
{
    emit_audit_message("attempting", hook, action, objName);
}
 
static void
audit_success(const char *hook, char *action, char *objName)
{
    emit_audit_message("finished", hook, action, objName);
}
 
static void
audit_failure(const char *hook, char *action, char *objName)
{
    emit_audit_message("denied", hook, action, objName);
}
 
static void
REGRESS_object_access_hook_str(ObjectAccessType access, Oid classId, const char *objName, int subId, void *arg)
{
    audit_attempt("object_access_hook_str",
                  accesstype_to_string(access, subId),
                  pstrdup(objName));
 
    if (next_object_access_hook_str)
    {
        (*next_object_access_hook_str) (access, classId, objName, subId, arg);
    }
 
    switch (access)
    {
        case OAT_POST_ALTER:
            if ((subId & ACL_SET) && (subId & ACL_ALTER_SYSTEM))
            {
                if (REGRESS_deny_set_variable && !superuser_arg(GetUserId()))
                    ereport(ERROR,
                            (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                             errmsg("permission denied: all privileges %s", objName)));
            }
            else if (subId & ACL_SET)
            {
                if (REGRESS_deny_set_variable && !superuser_arg(GetUserId()))
                    ereport(ERROR,
                            (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                             errmsg("permission denied: set %s", objName)));
            }
            else if (subId & ACL_ALTER_SYSTEM)
            {
                if (REGRESS_deny_alter_system && !superuser_arg(GetUserId()))
                    ereport(ERROR,
                            (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                             errmsg("permission denied: alter system set %s", objName)));
            }
            else
                elog(ERROR, "Unknown ParameterAclRelationId subId: %d", subId);
            break;
        default:
            break;
    }
 
    audit_success("object_access_hook_str",
                  accesstype_to_string(access, subId),
                  pstrdup(objName));
}
 
static void
REGRESS_object_access_hook(ObjectAccessType access, Oid classId, Oid objectId, int subId, void *arg)
{
    audit_attempt("object access",
                  accesstype_to_string(access, 0),
                  accesstype_arg_to_string(access, arg));
 
    if (REGRESS_deny_object_access && !superuser_arg(GetUserId()))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: %s [%s]",
                        accesstype_to_string(access, 0),
                        accesstype_arg_to_string(access, arg))));
 
    /* Forward to next hook in the chain */
    if (next_object_access_hook)
        (*next_object_access_hook) (access, classId, objectId, subId, arg);
 
    audit_success("object access",
                  accesstype_to_string(access, 0),
                  accesstype_arg_to_string(access, arg));
}
 
static bool
REGRESS_exec_check_perms(List *rangeTabls, List *rteperminfos, bool do_abort)
{
    bool        am_super = superuser_arg(GetUserId());
    bool        allow = true;
 
    audit_attempt("executor check perms", pstrdup("execute"), NULL);
 
    /* Perform our check */
    allow = !REGRESS_deny_exec_perms || am_super;
    if (do_abort && !allow)
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: %s", "execute")));
 
    /* Forward to next hook in the chain */
    if (next_exec_check_perms_hook &&
        !(*next_exec_check_perms_hook) (rangeTabls, rteperminfos, do_abort))
        allow = false;
 
    if (allow)
        audit_success("executor check perms",
                      pstrdup("execute"),
                      NULL);
    else
        audit_failure("executor check perms",
                      pstrdup("execute"),
                      NULL);
 
    return allow;
}
 
static void
REGRESS_utility_command(PlannedStmt *pstmt,
                        const char *queryString,
                        bool readOnlyTree,
                        ProcessUtilityContext context,
                        ParamListInfo params,
                        QueryEnvironment *queryEnv,
                        DestReceiver *dest,
                        QueryCompletion *qc)
{
    Node       *parsetree = pstmt->utilityStmt;
    const char *action = GetCommandTagName(CreateCommandTag(parsetree));
 
    audit_attempt("process utility",
                  pstrdup(action),
                  NULL);
 
    /* Check permissions */
    if (REGRESS_deny_utility_commands && !superuser_arg(GetUserId()))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied: %s", action)));
 
    /* Forward to next hook in the chain */
    if (next_ProcessUtility_hook)
        (*next_ProcessUtility_hook) (pstmt, queryString, readOnlyTree,
                                     context, params, queryEnv,
                                     dest, qc);
    else
        standard_ProcessUtility(pstmt, queryString, readOnlyTree,
                                context, params, queryEnv,
                                dest, qc);
 
    /* We're done */
    audit_success("process utility",
                  pstrdup(action),
                  NULL);
}
 
static char *
accesstype_to_string(ObjectAccessType access, int subId)
{
    const char *type;
 
    switch (access)
    {
        case OAT_POST_CREATE:
            type = "create";
            break;
        case OAT_DROP:
            type = "drop";
            break;
        case OAT_POST_ALTER:
            type = "alter";
            break;
        case OAT_NAMESPACE_SEARCH:
            type = "namespace search";
            break;
        case OAT_FUNCTION_EXECUTE:
            type = "execute";
            break;
        case OAT_TRUNCATE:
            type = "truncate";
            break;
        default:
            type = "UNRECOGNIZED ObjectAccessType";
    }
 
    if ((subId & ACL_SET) && (subId & ACL_ALTER_SYSTEM))
        return psprintf("%s (subId=0x%x, all privileges)", type, subId);
    if (subId & ACL_SET)
        return psprintf("%s (subId=0x%x, set)", type, subId);
    if (subId & ACL_ALTER_SYSTEM)
        return psprintf("%s (subId=0x%x, alter system)", type, subId);
 
    return psprintf("%s (subId=0x%x)", type, subId);
}
 
static char *
accesstype_arg_to_string(ObjectAccessType access, void *arg)
{
    if (arg == NULL)
        return pstrdup("extra info null");
 
    switch (access)
    {
        case OAT_POST_CREATE:
            {
                ObjectAccessPostCreate *pc_arg = (ObjectAccessPostCreate *) arg;
 
                return pstrdup(pc_arg->is_internal ? "internal" : "explicit");
            }
            break;
        case OAT_DROP:
            {
                ObjectAccessDrop *drop_arg = (ObjectAccessDrop *) arg;
 
                return psprintf("%s%s%s%s%s%s",
                                ((drop_arg->dropflags & PERFORM_DELETION_INTERNAL)
                                 ? "internal action," : ""),
                                ((drop_arg->dropflags & PERFORM_DELETION_CONCURRENTLY)
                                 ? "concurrent drop," : ""),
                                ((drop_arg->dropflags & PERFORM_DELETION_QUIETLY)
                                 ? "suppress notices," : ""),
                                ((drop_arg->dropflags & PERFORM_DELETION_SKIP_ORIGINAL)
                                 ? "keep original object," : ""),
                                ((drop_arg->dropflags & PERFORM_DELETION_SKIP_EXTENSIONS)
                                 ? "keep extensions," : ""),
                                ((drop_arg->dropflags & PERFORM_DELETION_CONCURRENT_LOCK)
                                 ? "normal concurrent drop," : ""));
            }
            break;
        case OAT_POST_ALTER:
            {
                ObjectAccessPostAlter *pa_arg = (ObjectAccessPostAlter *) arg;
 
                return psprintf("%s %s auxiliary object",
                                (pa_arg->is_internal ? "internal" : "explicit"),
                                (OidIsValid(pa_arg->auxiliary_id) ? "with" : "without"));
            }
            break;
        case OAT_NAMESPACE_SEARCH:
            {
                ObjectAccessNamespaceSearch *ns_arg = (ObjectAccessNamespaceSearch *) arg;
 
                return psprintf("%s, %s",
                                (ns_arg->ereport_on_violation ? "report on violation" : "no report on violation"),
                                (ns_arg->result ? "allowed" : "denied"));
            }
            break;
        case OAT_TRUNCATE:
        case OAT_FUNCTION_EXECUTE:
            /* hook takes no arg. */
            return pstrdup("unexpected extra info pointer received");
        default:
            return pstrdup("cannot parse extra info for unrecognized access type");
    }
 
    return pstrdup("unknown");
}