src/backend/utils/misc/superuser.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * superuser.c
   4  *        The superuser() function.  Determines if user has superuser privilege.
   5  *
   6  * All code should use either of these two functions to find out
   7  * whether a given user is a superuser, rather than examining
   8  * pg_authid.rolsuper directly, so that the escape hatch built in for
   9  * the single-user case works.
  10  *
  11  *
  12  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
  13  * Portions Copyright (c) 1994, Regents of the University of California
  14  *
  15  *
  16  * IDENTIFICATION
  17  *        src/backend/utils/misc/superuser.c
  18  *
  19  *-------------------------------------------------------------------------
  20  */
  21 #include "postgres.h"
  22
  23 #include "access/htup_details.h"
  24 #include "catalog/pg_authid.h"
  25 #include "miscadmin.h"
  26 #include "utils/inval.h"
  27 #include "utils/syscache.h"
  28
  29 /*
  30  * In common cases the same roleid (ie, the session or current ID) will
  31  * be queried repeatedly.  So we maintain a simple one-entry cache for
  32  * the status of the last requested roleid.  The cache can be flushed
  33  * at need by watching for cache update events on pg_authid.
  34  */
  35 static Oid      last_roleid = InvalidOid;       /* InvalidOid == cache not valid */
  36 static bool last_roleid_is_super = false;
  37 static bool roleid_callback_registered = false;
  38
  39 static void RoleidCallback(Datum arg, int cacheid, uint32 hashvalue);
  40
  41
  42 /*
  43  * The Postgres user running this command has Postgres superuser privileges
  44  */
  45 bool
  46 superuser(void)
  47 {
  48         return superuser_arg(GetUserId());
  49 }
  50
  51
  52 /*
  53  * The specified role has Postgres superuser privileges
  54  */
  55 bool
  56 superuser_arg(Oid roleid)
  57 {
  58         bool            result;
  59         HeapTuple       rtup;
  60
  61         /* Quick out for cache hit */
  62         if (OidIsValid(last_roleid) && last_roleid == roleid)
  63                 return last_roleid_is_super;
  64
  65         /* Special escape path in case you deleted all your users. */
  66         if (!IsUnderPostmaster && roleid == BOOTSTRAP_SUPERUSERID)
  67                 return true;
  68
  69         /* OK, look up the information in pg_authid */
  70         rtup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
  71         if (HeapTupleIsValid(rtup))
  72         {
  73                 result = ((Form_pg_authid) GETSTRUCT(rtup))->rolsuper;
  74                 ReleaseSysCache(rtup);
  75         }
  76         else
  77         {
  78                 /* Report "not superuser" for invalid roleids */
  79                 result = false;
  80         }
  81
  82         /* If first time through, set up callback for cache flushes */
  83         if (!roleid_callback_registered)
  84         {
  85                 CacheRegisterSyscacheCallback(AUTHOID,
  86                                                                           RoleidCallback,
  87                                                                           (Datum) 0);
  88                 roleid_callback_registered = true;
  89         }
  90
  91         /* Cache the result for next time */
  92         last_roleid = roleid;
  93         last_roleid_is_super = result;
  94
  95         return result;
  96 }
  97
  98 /*
  99  * RoleidCallback
 100  *              Syscache inval callback function
 101  */
 102 static void
 103 RoleidCallback(Datum arg, int cacheid, uint32 hashvalue)
 104 {
 105         /* Invalidate our local cache in case role's superuserness changed */
 106         last_roleid = InvalidOid;
 107 }