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Commit7eed723

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Fix corner-case failures in has_foo_privilege() family of functions.
The variants of these functions that take numeric inputs (OIDs orcolumn numbers) are supposed to return NULL rather than failingon bad input; this rule reduces problems with snapshot skew whenqueries apply the functions to all rows of a catalog.has_column_privilege() had careless handling of the case where thetable OID didn't exist. You might get something like this:select has_column_privilege(9999,'nosuchcol','select');ERROR: column "nosuchcol" of relation "(null)" does not existor you might get a crash, depending on the platform's printf's responseto a null string pointer.In addition, while applying the column-number variant to a droppedcolumn returned NULL as desired, applying the column-name variantdid not:select has_column_privilege('mytable','........pg.dropped.2........','select');ERROR: column "........pg.dropped.2........" of relation "mytable" does not existIt seems better to make this case return NULL as well.Also, the OID-accepting variants of has_foreign_data_wrapper_privilege,has_server_privilege, and has_tablespace_privilege didn't follow theprinciple of returning NULL for nonexistent OIDs. Superusers got TRUE,everybody else got an error.Per investigation of Jaime Casanova's report of a new crash in HEAD.These behaviors have been like this for a long time, so back-patch toall supported branches.Patch by me; thanks to Stephen Frost for discussion and reviewDiscussion:https://postgr.es/m/CAJGNTeP=-6Gyqq5TN9OvYEydi7Fv1oGyYj650LGTnW44oAzYCg@mail.gmail.com
1 parent5dd7f5c commit7eed723

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3 files changed

+159
-10
lines changed

3 files changed

+159
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‎src/backend/utils/adt/acl.c

Lines changed: 85 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -2433,8 +2433,12 @@ has_any_column_privilege_id_id(PG_FUNCTION_ARGS)
24332433
*
24342434
*The result is a boolean value: true if user has the indicated
24352435
*privilege, false if not. The variants that take a relation OID
2436-
*and an integer attnum return NULL (rather than throwing an error)
2437-
*if the column doesn't exist or is dropped.
2436+
*return NULL (rather than throwing an error) if that relation OID
2437+
*doesn't exist. Likewise, the variants that take an integer attnum
2438+
*return NULL (rather than throwing an error) if there is no such
2439+
*pg_attribute entry. All variants return NULL if an attisdropped
2440+
*column is selected. These rules are meant to avoid unnecessary
2441+
*failures in queries that scan pg_attribute.
24382442
*/
24392443

24402444
/*
@@ -2451,6 +2455,12 @@ column_privilege_check(Oid tableoid, AttrNumber attnum,
24512455
HeapTupleattTuple;
24522456
Form_pg_attributeattributeForm;
24532457

2458+
/*
2459+
* If convert_column_name failed, we can just return -1 immediately.
2460+
*/
2461+
if (attnum==InvalidAttrNumber)
2462+
return-1;
2463+
24542464
/*
24552465
* First check if we have the privilege at the table level. We check
24562466
* existence of the pg_class row before risking calling pg_class_aclcheck.
@@ -2812,21 +2822,59 @@ has_column_privilege_id_attnum(PG_FUNCTION_ARGS)
28122822

28132823
/*
28142824
* Given a table OID and a column name expressed as a string, look it up
2815-
* and return the column number
2825+
* and return the column number. Returns InvalidAttrNumber in cases
2826+
* where caller should return NULL instead of failing.
28162827
*/
28172828
staticAttrNumber
28182829
convert_column_name(Oidtableoid,text*column)
28192830
{
2820-
AttrNumberattnum;
28212831
char*colname;
2832+
HeapTupleattTuple;
2833+
AttrNumberattnum;
28222834

28232835
colname=text_to_cstring(column);
2824-
attnum=get_attnum(tableoid,colname);
2825-
if (attnum==InvalidAttrNumber)
2826-
ereport(ERROR,
2827-
(errcode(ERRCODE_UNDEFINED_COLUMN),
2828-
errmsg("column \"%s\" of relation \"%s\" does not exist",
2829-
colname,get_rel_name(tableoid))));
2836+
2837+
/*
2838+
* We don't use get_attnum() here because it will report that dropped
2839+
* columns don't exist. We need to treat dropped columns differently from
2840+
* nonexistent columns.
2841+
*/
2842+
attTuple=SearchSysCache2(ATTNAME,
2843+
ObjectIdGetDatum(tableoid),
2844+
CStringGetDatum(colname));
2845+
if (HeapTupleIsValid(attTuple))
2846+
{
2847+
Form_pg_attributeattributeForm;
2848+
2849+
attributeForm= (Form_pg_attribute)GETSTRUCT(attTuple);
2850+
/* We want to return NULL for dropped columns */
2851+
if (attributeForm->attisdropped)
2852+
attnum=InvalidAttrNumber;
2853+
else
2854+
attnum=attributeForm->attnum;
2855+
ReleaseSysCache(attTuple);
2856+
}
2857+
else
2858+
{
2859+
char*tablename=get_rel_name(tableoid);
2860+
2861+
/*
2862+
* If the table OID is bogus, or it's just been dropped, we'll get
2863+
* NULL back. In such cases we want has_column_privilege to return
2864+
* NULL too, so just return InvalidAttrNumber.
2865+
*/
2866+
if (tablename!=NULL)
2867+
{
2868+
/* tableoid exists, colname does not, so throw error */
2869+
ereport(ERROR,
2870+
(errcode(ERRCODE_UNDEFINED_COLUMN),
2871+
errmsg("column \"%s\" of relation \"%s\" does not exist",
2872+
colname,tablename)));
2873+
}
2874+
/* tableoid doesn't exist, so act like attisdropped case */
2875+
attnum=InvalidAttrNumber;
2876+
}
2877+
28302878
pfree(colname);
28312879
returnattnum;
28322880
}
@@ -3130,6 +3178,9 @@ has_foreign_data_wrapper_privilege_name_id(PG_FUNCTION_ARGS)
31303178
roleid=get_role_oid_or_public(NameStr(*username));
31313179
mode=convert_foreign_data_wrapper_priv_string(priv_type_text);
31323180

3181+
if (!SearchSysCacheExists1(FOREIGNDATAWRAPPEROID,ObjectIdGetDatum(fdwid)))
3182+
PG_RETURN_NULL();
3183+
31333184
aclresult=pg_foreign_data_wrapper_aclcheck(fdwid,roleid,mode);
31343185

31353186
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -3153,6 +3204,9 @@ has_foreign_data_wrapper_privilege_id(PG_FUNCTION_ARGS)
31533204
roleid=GetUserId();
31543205
mode=convert_foreign_data_wrapper_priv_string(priv_type_text);
31553206

3207+
if (!SearchSysCacheExists1(FOREIGNDATAWRAPPEROID,ObjectIdGetDatum(fdwid)))
3208+
PG_RETURN_NULL();
3209+
31563210
aclresult=pg_foreign_data_wrapper_aclcheck(fdwid,roleid,mode);
31573211

31583212
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -3197,6 +3251,9 @@ has_foreign_data_wrapper_privilege_id_id(PG_FUNCTION_ARGS)
31973251

31983252
mode=convert_foreign_data_wrapper_priv_string(priv_type_text);
31993253

3254+
if (!SearchSysCacheExists1(FOREIGNDATAWRAPPEROID,ObjectIdGetDatum(fdwid)))
3255+
PG_RETURN_NULL();
3256+
32003257
aclresult=pg_foreign_data_wrapper_aclcheck(fdwid,roleid,mode);
32013258

32023259
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -3896,6 +3953,9 @@ has_server_privilege_name_id(PG_FUNCTION_ARGS)
38963953
roleid=get_role_oid_or_public(NameStr(*username));
38973954
mode=convert_server_priv_string(priv_type_text);
38983955

3956+
if (!SearchSysCacheExists1(FOREIGNSERVEROID,ObjectIdGetDatum(serverid)))
3957+
PG_RETURN_NULL();
3958+
38993959
aclresult=pg_foreign_server_aclcheck(serverid,roleid,mode);
39003960

39013961
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -3919,6 +3979,9 @@ has_server_privilege_id(PG_FUNCTION_ARGS)
39193979
roleid=GetUserId();
39203980
mode=convert_server_priv_string(priv_type_text);
39213981

3982+
if (!SearchSysCacheExists1(FOREIGNSERVEROID,ObjectIdGetDatum(serverid)))
3983+
PG_RETURN_NULL();
3984+
39223985
aclresult=pg_foreign_server_aclcheck(serverid,roleid,mode);
39233986

39243987
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -3963,6 +4026,9 @@ has_server_privilege_id_id(PG_FUNCTION_ARGS)
39634026

39644027
mode=convert_server_priv_string(priv_type_text);
39654028

4029+
if (!SearchSysCacheExists1(FOREIGNSERVEROID,ObjectIdGetDatum(serverid)))
4030+
PG_RETURN_NULL();
4031+
39664032
aclresult=pg_foreign_server_aclcheck(serverid,roleid,mode);
39674033

39684034
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -4078,6 +4144,9 @@ has_tablespace_privilege_name_id(PG_FUNCTION_ARGS)
40784144
roleid=get_role_oid_or_public(NameStr(*username));
40794145
mode=convert_tablespace_priv_string(priv_type_text);
40804146

4147+
if (!SearchSysCacheExists1(TABLESPACEOID,ObjectIdGetDatum(tablespaceoid)))
4148+
PG_RETURN_NULL();
4149+
40814150
aclresult=pg_tablespace_aclcheck(tablespaceoid,roleid,mode);
40824151

40834152
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -4101,6 +4170,9 @@ has_tablespace_privilege_id(PG_FUNCTION_ARGS)
41014170
roleid=GetUserId();
41024171
mode=convert_tablespace_priv_string(priv_type_text);
41034172

4173+
if (!SearchSysCacheExists1(TABLESPACEOID,ObjectIdGetDatum(tablespaceoid)))
4174+
PG_RETURN_NULL();
4175+
41044176
aclresult=pg_tablespace_aclcheck(tablespaceoid,roleid,mode);
41054177

41064178
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);
@@ -4145,6 +4217,9 @@ has_tablespace_privilege_id_id(PG_FUNCTION_ARGS)
41454217

41464218
mode=convert_tablespace_priv_string(priv_type_text);
41474219

4220+
if (!SearchSysCacheExists1(TABLESPACEOID,ObjectIdGetDatum(tablespaceoid)))
4221+
PG_RETURN_NULL();
4222+
41484223
aclresult=pg_tablespace_aclcheck(tablespaceoid,roleid,mode);
41494224

41504225
PG_RETURN_BOOL(aclresult==ACLCHECK_OK);

‎src/test/regress/expected/privileges.out

Lines changed: 57 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1098,6 +1098,63 @@ from (select oid from pg_class where relname = 'atest1') as t1;
10981098
f
10991099
(1 row)
11001100

1101+
-- has_column_privilege function
1102+
-- bad-input checks (as non-super-user)
1103+
select has_column_privilege('pg_authid',NULL,'select');
1104+
has_column_privilege
1105+
----------------------
1106+
1107+
(1 row)
1108+
1109+
select has_column_privilege('pg_authid','nosuchcol','select');
1110+
ERROR: column "nosuchcol" of relation "pg_authid" does not exist
1111+
select has_column_privilege(9999,'nosuchcol','select');
1112+
has_column_privilege
1113+
----------------------
1114+
1115+
(1 row)
1116+
1117+
select has_column_privilege(9999,99::int2,'select');
1118+
has_column_privilege
1119+
----------------------
1120+
1121+
(1 row)
1122+
1123+
select has_column_privilege('pg_authid',99::int2,'select');
1124+
has_column_privilege
1125+
----------------------
1126+
1127+
(1 row)
1128+
1129+
select has_column_privilege(9999,99::int2,'select');
1130+
has_column_privilege
1131+
----------------------
1132+
1133+
(1 row)
1134+
1135+
create temp table mytable(f1 int, f2 int, f3 int);
1136+
alter table mytable drop column f2;
1137+
select has_column_privilege('mytable','f2','select');
1138+
ERROR: column "f2" of relation "mytable" does not exist
1139+
select has_column_privilege('mytable','........pg.dropped.2........','select');
1140+
has_column_privilege
1141+
----------------------
1142+
1143+
(1 row)
1144+
1145+
select has_column_privilege('mytable',2::int2,'select');
1146+
has_column_privilege
1147+
----------------------
1148+
t
1149+
(1 row)
1150+
1151+
revoke select on table mytable from regress_user3;
1152+
select has_column_privilege('mytable',2::int2,'select');
1153+
has_column_privilege
1154+
----------------------
1155+
1156+
(1 row)
1157+
11011158
-- Grant options
11021159
SET SESSION AUTHORIZATION regress_user1;
11031160
CREATE TABLE atest4 (a int);

‎src/test/regress/sql/privileges.sql

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -698,6 +698,23 @@ from (select oid from pg_class where relname = 'atest1') as t1;
698698
select has_table_privilege(t1.oid,'trigger')
699699
from (selectoidfrom pg_classwhere relname='atest1')as t1;
700700

701+
-- has_column_privilege function
702+
703+
-- bad-input checks (as non-super-user)
704+
select has_column_privilege('pg_authid',NULL,'select');
705+
select has_column_privilege('pg_authid','nosuchcol','select');
706+
select has_column_privilege(9999,'nosuchcol','select');
707+
select has_column_privilege(9999,99::int2,'select');
708+
select has_column_privilege('pg_authid',99::int2,'select');
709+
select has_column_privilege(9999,99::int2,'select');
710+
711+
create temp table mytable(f1int, f2int, f3int);
712+
altertable mytable drop column f2;
713+
select has_column_privilege('mytable','f2','select');
714+
select has_column_privilege('mytable','........pg.dropped.2........','select');
715+
select has_column_privilege('mytable',2::int2,'select');
716+
revokeselecton table mytablefrom regress_user3;
717+
select has_column_privilege('mytable',2::int2,'select');
701718

702719
-- Grant options
703720

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