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) 1996-2019, 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 "utils/inval.h"
26#include "utils/syscache.h"
27#include "miscadmin.h"
28
29
30/*
31 * In common cases the same roleid (ie, the session or current ID) will
32 * be queried repeatedly. So we maintain a simple one-entry cache for
33 * the status of the last requested roleid. The cache can be flushed
34 * at need by watching for cache update events on pg_authid.
35 */
36static Oid last_roleid = InvalidOid; /* InvalidOid == cache not valid */
37static bool last_roleid_is_super = false;
38static bool roleid_callback_registered = false;
39
40static void RoleidCallback(Datum arg, int cacheid, uint32 hashvalue);
41
42
43/*
44 * The Postgres user running this command has Postgres superuser privileges
45 */
46bool
47superuser(void)
48{
49 return superuser_arg(GetUserId());
50}
51
52
53/*
54 * The specified role has Postgres superuser privileges
55 */
56bool
57superuser_arg(Oid roleid)
58{
59 bool result;
60 HeapTuple rtup;
61
62 /* Quick out for cache hit */
63 if (OidIsValid(last_roleid) && last_roleid == roleid)
64 return last_roleid_is_super;
65
66 /* Special escape path in case you deleted all your users. */
67 if (!IsUnderPostmaster && roleid == BOOTSTRAP_SUPERUSERID)
68 return true;
69
70 /* OK, look up the information in pg_authid */
71 rtup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));
72 if (HeapTupleIsValid(rtup))
73 {
74 result = ((Form_pg_authid) GETSTRUCT(rtup))->rolsuper;
75 ReleaseSysCache(rtup);
76 }
77 else
78 {
79 /* Report "not superuser" for invalid roleids */
80 result = false;
81 }
82
83 /* If first time through, set up callback for cache flushes */
84 if (!roleid_callback_registered)
85 {
86 CacheRegisterSyscacheCallback(AUTHOID,
87 RoleidCallback,
88 (Datum) 0);
89 roleid_callback_registered = true;
90 }
91
92 /* Cache the result for next time */
93 last_roleid = roleid;
94 last_roleid_is_super = result;
95
96 return result;
97}
98
99/*
100 * RoleidCallback
101 * Syscache inval callback function
102 */
103static void
104RoleidCallback(Datum arg, int cacheid, uint32 hashvalue)
105{
106 /* Invalidate our local cache in case role's superuserness changed */
107 last_roleid = InvalidOid;
108}
109