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rls.c
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1 /*-------------------------------------------------------------------------
2  *
3  * rls.c
4  * RLS-related utility functions.
5  *
6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/utils/misc/rls.c
12  *
13  *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16 
17 #include "access/htup.h"
18 #include "access/htup_details.h"
19 #include "access/transam.h"
20 #include "catalog/namespace.h"
21 #include "catalog/pg_class.h"
22 #include "miscadmin.h"
23 #include "utils/acl.h"
24 #include "utils/builtins.h"
25 #include "utils/elog.h"
26 #include "utils/lsyscache.h"
27 #include "utils/rls.h"
28 #include "utils/syscache.h"
29 #include "utils/varlena.h"
30 
31 
32 /*
33  * check_enable_rls
34  *
35  * Determine, based on the relation, row_security setting, and current role,
36  * if RLS is applicable to this query. RLS_NONE_ENV indicates that, while
37  * RLS is not to be added for this query, a change in the environment may change
38  * that. RLS_NONE means that RLS is not on the relation at all and therefore
39  * we don't need to worry about it. RLS_ENABLED means RLS should be implemented
40  * for the table and the plan cache needs to be invalidated if the environment
41  * changes.
42  *
43  * Handle checking as another role via checkAsUser (for views, etc). Pass
44  * InvalidOid to check the current user.
45  *
46  * If noError is set to 'true' then we just return RLS_ENABLED instead of doing
47  * an ereport() if the user has attempted to bypass RLS and they are not
48  * allowed to. This allows users to check if RLS is enabled without having to
49  * deal with the actual error case (eg: error cases which are trying to decide
50  * if the user should get data from the relation back as part of the error).
51  */
52 int
53 check_enable_rls(Oid relid, Oid checkAsUser, bool noError)
54 {
55  Oid user_id = checkAsUser ? checkAsUser : GetUserId();
56  HeapTuple tuple;
57  Form_pg_class classform;
58  bool relrowsecurity;
59  bool relforcerowsecurity;
60  bool amowner;
61 
62  /* Nothing to do for built-in relations */
63  if (relid < (Oid) FirstNormalObjectId)
64  return RLS_NONE;
65 
66  /* Fetch relation's relrowsecurity and relforcerowsecurity flags */
67  tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
68  if (!HeapTupleIsValid(tuple))
69  return RLS_NONE;
70  classform = (Form_pg_class) GETSTRUCT(tuple);
71 
72  relrowsecurity = classform->relrowsecurity;
73  relforcerowsecurity = classform->relforcerowsecurity;
74 
75  ReleaseSysCache(tuple);
76 
77  /* Nothing to do if the relation does not have RLS */
78  if (!relrowsecurity)
79  return RLS_NONE;
80 
81  /*
82  * BYPASSRLS users always bypass RLS. Note that superusers are always
83  * considered to have BYPASSRLS.
84  *
85  * Return RLS_NONE_ENV to indicate that this decision depends on the
86  * environment (in this case, the user_id).
87  */
88  if (has_bypassrls_privilege(user_id))
89  return RLS_NONE_ENV;
90 
91  /*
92  * Table owners generally bypass RLS, except if the table has been set (by
93  * an owner) to FORCE ROW SECURITY, and this is not a referential
94  * integrity check.
95  *
96  * Return RLS_NONE_ENV to indicate that this decision depends on the
97  * environment (in this case, the user_id).
98  */
99  amowner = pg_class_ownercheck(relid, user_id);
100  if (amowner)
101  {
102  /*
103  * If FORCE ROW LEVEL SECURITY has been set on the relation then we
104  * should return RLS_ENABLED to indicate that RLS should be applied.
105  * If not, or if we are in an InNoForceRLSOperation context, we return
106  * RLS_NONE_ENV.
107  *
108  * InNoForceRLSOperation indicates that we should not apply RLS even
109  * if the table has FORCE RLS set - IF the current user is the owner.
110  * This is specifically to ensure that referential integrity checks
111  * are able to still run correctly.
112  *
113  * This is intentionally only done after we have checked that the user
114  * is the table owner, which should always be the case for referential
115  * integrity checks.
116  */
117  if (!relforcerowsecurity || InNoForceRLSOperation())
118  return RLS_NONE_ENV;
119  }
120 
121  /*
122  * We should apply RLS. However, the user may turn off the row_security
123  * GUC to get a forced error instead.
124  */
125  if (!row_security && !noError)
126  ereport(ERROR,
127  (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
128  errmsg("query would be affected by row-level security policy for table \"%s\"",
129  get_rel_name(relid)),
130  amowner ? errhint("To disable the policy for the table's owner, use ALTER TABLE NO FORCE ROW LEVEL SECURITY.") : 0));
131 
132  /* RLS should be fully enabled for this relation. */
133  return RLS_ENABLED;
134 }
135 
136 /*
137  * row_security_active
138  *
139  * check_enable_rls wrapped as a SQL callable function except
140  * RLS_NONE_ENV and RLS_NONE are the same for this purpose.
141  */
142 Datum
144 {
145  /* By OID */
146  Oid tableoid = PG_GETARG_OID(0);
147  int rls_status;
148 
149  rls_status = check_enable_rls(tableoid, InvalidOid, true);
150  PG_RETURN_BOOL(rls_status == RLS_ENABLED);
151 }
152 
153 Datum
155 {
156  /* By qualified name */
157  text *tablename = PG_GETARG_TEXT_PP(0);
158  RangeVar *tablerel;
159  Oid tableoid;
160  int rls_status;
161 
162  /* Look up table name. Can't lock it - we might not have privileges. */
163  tablerel = makeRangeVarFromNameList(textToQualifiedNameList(tablename));
164  tableoid = RangeVarGetRelid(tablerel, NoLock, false);
165 
166  rls_status = check_enable_rls(tableoid, InvalidOid, true);
167  PG_RETURN_BOOL(rls_status == RLS_ENABLED);
168 }
int errhint(const char *fmt,...)
Definition: elog.c:987
#define GETSTRUCT(TUP)
Definition: htup_details.h:661
Oid GetUserId(void)
Definition: miscinit.c:284
#define RangeVarGetRelid(relation, lockmode, missing_ok)
Definition: namespace.h:53
int errcode(int sqlerrcode)
Definition: elog.c:575
bool InNoForceRLSOperation(void)
Definition: miscinit.c:425
RangeVar * makeRangeVarFromNameList(List *names)
Definition: namespace.c:3023
unsigned int Oid
Definition: postgres_ext.h:31
#define FirstNormalObjectId
Definition: transam.h:94
#define PG_GETARG_TEXT_PP(n)
Definition: fmgr.h:273
bool has_bypassrls_privilege(Oid roleid)
Definition: aclchk.c:5248
#define ObjectIdGetDatum(X)
Definition: postgres.h:513
#define ERROR
Definition: elog.h:43
#define NoLock
Definition: lockdefs.h:34
#define PG_GETARG_OID(n)
Definition: fmgr.h:240
#define ereport(elevel, rest)
Definition: elog.h:122
List * textToQualifiedNameList(text *textval)
Definition: varlena.c:3205
HeapTuple SearchSysCache1(int cacheId, Datum key1)
Definition: syscache.c:1112
#define PG_RETURN_BOOL(x)
Definition: fmgr.h:319
uintptr_t Datum
Definition: postgres.h:372
void ReleaseSysCache(HeapTuple tuple)
Definition: syscache.c:1160
#define InvalidOid
Definition: postgres_ext.h:36
int check_enable_rls(Oid relid, Oid checkAsUser, bool noError)
Definition: rls.c:53
#define HeapTupleIsValid(tuple)
Definition: htup.h:77
bool row_security
Definition: guc.c:446
bool pg_class_ownercheck(Oid class_oid, Oid roleid)
Definition: aclchk.c:4604
FormData_pg_class * Form_pg_class
Definition: pg_class.h:95
Datum row_security_active(PG_FUNCTION_ARGS)
Definition: rls.c:143
int errmsg(const char *fmt,...)
Definition: elog.c:797
Definition: c.h:497
#define PG_FUNCTION_ARGS
Definition: fmgr.h:158
Datum row_security_active_name(PG_FUNCTION_ARGS)
Definition: rls.c:154
Definition: rls.h:43
char * get_rel_name(Oid relid)
Definition: lsyscache.c:1745