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Fix mishandling of column-level SELECT privileges for join aliases. 

scanNSItemForColumn, expandNSItemAttrs, and ExpandSingleTable would
pass the wrong RTE to markVarForSelectPriv when dealing with a join
ParseNamespaceItem: they'd pass the join RTE, when what we need to
mark is the base table that the join column came from.  The end
result was to not fill the base table's selectedCols bitmap correctly,
resulting in an understatement of the set of columns that are read
by the query.  The executor would still insist on there being at
least one selectable column; but with a correctly crafted query,
a user having SELECT privilege on just one column of a table would
nonetheless be allowed to read all its columns.

To fix, make markRTEForSelectPriv fetch the correct RTE for itself,
ignoring the possibly-mismatched RTE passed by the caller.  Later,
we'll get rid of some now-unused RTE arguments, but that risks
API breaks so we won't do it in released branches.

This problem was introduced by commit 9ce77d75c, so back-patch
to v13 where that came in.  Thanks to Sven Klemm for reporting
the problem.

Security: CVE-2021-20229
This commit is contained in:
Tom Lane 2021-02-08 10:14:09 -05:00
parent 6214e2b228
commit c028faf2a6
4 changed files with 93 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
src/backend/parser/parse_relation.c
View File

@ -68,7 +68,7 @@ static int scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte,
const char *colname, int location,
int fuzzy_rte_penalty,
FuzzyAttrMatchState *fuzzystate);
static void markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
static void markRTEForSelectPriv(ParseState *pstate,
int rtindex, AttrNumber col);
static void expandRelation(Oid relid, Alias *eref,
int rtindex, int sublevels_up,
@ -660,8 +660,8 @@ updateFuzzyAttrMatchState(int fuzzy_rte_penalty,
* If found, return an appropriate Var node, else return NULL.
* If the name proves ambiguous within this nsitem, raise error.
*
* Side effect: if we find a match, mark the item's RTE as requiring read
* access for the column.
* Side effect: if we find a match, mark the corresponding RTE as requiring
* read access for the column.
*/
Node *
scanNSItemForColumn(ParseState *pstate, ParseNamespaceItem *nsitem,
@ -990,21 +990,15 @@ searchRangeTableForCol(ParseState *pstate, const char *alias, const char *colnam
/*
* markRTEForSelectPriv
* Mark the specified column of an RTE as requiring SELECT privilege
* Mark the specified column of the RTE with index rtindex
* as requiring SELECT privilege
*
* col == InvalidAttrNumber means a "whole row" reference
*
* External callers should always pass the Var's RTE. Internally, we
* allow NULL to be passed for the RTE and then look it up if needed;
* this takes less code than requiring each internal recursion site
* to perform a lookup.
*/
static void
markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
int rtindex, AttrNumber col)
markRTEForSelectPriv(ParseState *pstate, int rtindex, AttrNumber col)
{
if (rte == NULL)
rte = rt_fetch(rtindex, pstate->p_rtable);
RangeTblEntry *rte = rt_fetch(rtindex, pstate->p_rtable);
if (rte->rtekind == RTE_RELATION)
{
@ -1036,13 +1030,13 @@ markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
{
int varno = ((RangeTblRef *) j->larg)->rtindex;
markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
markRTEForSelectPriv(pstate, varno, InvalidAttrNumber);
}
else if (IsA(j->larg, JoinExpr))
{
int varno = ((JoinExpr *) j->larg)->rtindex;
markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
markRTEForSelectPriv(pstate, varno, InvalidAttrNumber);
}
else
elog(ERROR, "unrecognized node type: %d",
@ -1051,13 +1045,13 @@ markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
{
int varno = ((RangeTblRef *) j->rarg)->rtindex;
markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
markRTEForSelectPriv(pstate, varno, InvalidAttrNumber);
}
else if (IsA(j->rarg, JoinExpr))
{
int varno = ((JoinExpr *) j->rarg)->rtindex;
markRTEForSelectPriv(pstate, NULL, varno, InvalidAttrNumber);
markRTEForSelectPriv(pstate, varno, InvalidAttrNumber);
}
else
elog(ERROR, "unrecognized node type: %d",
@ -1078,7 +1072,10 @@ markRTEForSelectPriv(ParseState *pstate, RangeTblEntry *rte,
/*
* markVarForSelectPriv
* Mark the RTE referenced by a Var as requiring SELECT privilege
* Mark the RTE referenced by the Var as requiring SELECT privilege
* for the Var's column (the Var could be a whole-row Var, too)
*
* The rte argument is unused and will be removed later.
*/
void
markVarForSelectPriv(ParseState *pstate, Var *var, RangeTblEntry *rte)
@ -1089,7 +1086,7 @@ markVarForSelectPriv(ParseState *pstate, Var *var, RangeTblEntry *rte)
/* Find the appropriate pstate if it's an uplevel Var */
for (lv = 0; lv < var->varlevelsup; lv++)
pstate = pstate->parentParseState;
markRTEForSelectPriv(pstate, rte, var->varno, var->varattno);
markRTEForSelectPriv(pstate, var->varno, var->varattno);
}
/*
@ -3105,9 +3102,13 @@ expandNSItemAttrs(ParseState *pstate, ParseNamespaceItem *nsitem,
/*
* Require read access to the table. This is normally redundant with the
* markVarForSelectPriv calls below, but not if the table has zero
* columns.
* columns. We need not do anything if the nsitem is for a join: its
* component tables will have been marked ACL_SELECT when they were added
* to the rangetable. (This step changes things only for the target
* relation of UPDATE/DELETE, which cannot be under a join.)
*/
rte->requiredPerms |= ACL_SELECT;
if (rte->rtekind == RTE_RELATION)
rte->requiredPerms |= ACL_SELECT;
forboth(name, names, var, vars)
{

8
src/backend/parser/parse_target.c
View File

@ -1384,9 +1384,13 @@ ExpandSingleTable(ParseState *pstate, ParseNamespaceItem *nsitem,
/*
* Require read access to the table. This is normally redundant with
* the markVarForSelectPriv calls below, but not if the table has zero
* columns.
* columns. We need not do anything if the nsitem is for a join: its
* component tables will have been marked ACL_SELECT when they were
* added to the rangetable. (This step changes things only for the
* target relation of UPDATE/DELETE, which cannot be under a join.)
*/
rte->requiredPerms |= ACL_SELECT;
if (rte->rtekind == RTE_RELATION)
rte->requiredPerms |= ACL_SELECT;
/* Require read access to each column */
foreach(l, vars)

46
src/test/regress/expected/privileges.out
View File

@ -476,8 +476,54 @@ SELECT 1 FROM atest5 a JOIN atest5 b USING (two); -- fail
ERROR: permission denied for table atest5
SELECT 1 FROM atest5 a NATURAL JOIN atest5 b; -- fail
ERROR: permission denied for table atest5
SELECT * FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT j.* FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT (j.*) IS NULL FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT one FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- ok
one
-----
1
(1 row)
SELECT j.one FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- ok
one
-----
1
(1 row)
SELECT two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT j.two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT j.y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
ERROR: permission denied for table atest5
SELECT * FROM (atest5 a JOIN atest5 b USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT a.* FROM (atest5 a JOIN atest5 b USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT (a.*) IS NULL FROM (atest5 a JOIN atest5 b USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT a.two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT b.y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT y FROM (atest5 a LEFT JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT b.y FROM (atest5 a LEFT JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT y FROM (atest5 a FULL JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT b.y FROM (atest5 a FULL JOIN atest5 b(one,x,y,z) USING (one)); -- fail
ERROR: permission denied for table atest5
SELECT 1 FROM atest5 WHERE two = 2; -- fail
ERROR: permission denied for table atest5
SELECT * FROM atest1, atest5; -- fail

19
src/test/regress/sql/privileges.sql
View File

@ -303,7 +303,26 @@ SELECT 1 FROM atest5; -- ok
SELECT 1 FROM atest5 a JOIN atest5 b USING (one); -- ok
SELECT 1 FROM atest5 a JOIN atest5 b USING (two); -- fail
SELECT 1 FROM atest5 a NATURAL JOIN atest5 b; -- fail
SELECT * FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
SELECT j.* FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
SELECT (j.*) IS NULL FROM (atest5 a JOIN atest5 b USING (one)) j; -- fail
SELECT one FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- ok
SELECT j.one FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- ok
SELECT two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
SELECT j.two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
SELECT y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
SELECT j.y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)) j; -- fail
SELECT * FROM (atest5 a JOIN atest5 b USING (one)); -- fail
SELECT a.* FROM (atest5 a JOIN atest5 b USING (one)); -- fail
SELECT (a.*) IS NULL FROM (atest5 a JOIN atest5 b USING (one)); -- fail
SELECT two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT a.two FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT b.y FROM (atest5 a JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT y FROM (atest5 a LEFT JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT b.y FROM (atest5 a LEFT JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT y FROM (atest5 a FULL JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT b.y FROM (atest5 a FULL JOIN atest5 b(one,x,y,z) USING (one)); -- fail
SELECT 1 FROM atest5 WHERE two = 2; -- fail
SELECT * FROM atest1, atest5; -- fail
SELECT atest1.* FROM atest1, atest5; -- ok