/*--------------------------------------------------------------------------
 *
 * test_oat_hooks.c
 *  Code for testing mandatory access control (MAC) using object access hooks.
 *
 * Copyright (c) 2015-2025, 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 "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,
        ®RESS_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,
        ®RESS_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,
        ®RESS_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,
        ®RESS_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,
        ®RESS_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,
        ®RESS_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,
        ®RESS_userset_variable1,
        false,
        PGC_USERSET,
        GUC_NOT_IN_SAMPLE,
        NULL,
        NULL,
        NULL);

 DefineCustomBoolVariable("test_oat_hooks.user_var2",
        "Dummy parameter settable by public",
        NULL,
        ®RESS_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,
        ®RESS_suset_variable1,
        false,
        PGC_SUSET,
        GUC_NOT_IN_SAMPLE,
        NULL,
        NULL,
        NULL);

 DefineCustomBoolVariable("test_oat_hooks.super_var2",
        "Dummy parameter settable by superuser",
        NULL,
        ®RESS_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");
}