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Rework query relation permission checking

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Currently, information about the permissions to be checked on relations
mentioned in a query is stored in their range table entries.  So the
executor must scan the entire range table looking for relations that
need to have permissions checked.  This can make the permission checking
part of the executor initialization needlessly expensive when many
inheritance children are present in the range range.  While the
permissions need not be checked on the individual child relations, the
executor still must visit every range table entry to filter them out.

This commit moves the permission checking information out of the range
table entries into a new plan node called RTEPermissionInfo.  Every
top-level (inheritance "root") RTE_RELATION entry in the range table
gets one and a list of those is maintained alongside the range table.
This new list is initialized by the parser when initializing the range
table.  The rewriter can add more entries to it as rules/views are
expanded.  Finally, the planner combines the lists of the individual
subqueries into one flat list that is passed to the executor for
checking.

To make it quick to find the RTEPermissionInfo entry belonging to a
given relation, RangeTblEntry gets a new Index field 'perminfoindex'
that stores the corresponding RTEPermissionInfo's index in the query's
list of the latter.

ExecutorCheckPerms_hook has gained another List * argument; the
signature is now:
typedef bool (*ExecutorCheckPerms_hook_type) (List *rangeTable,
					      List *rtePermInfos,
					      bool ereport_on_violation);
The first argument is no longer used by any in-core uses of the hook,
but we leave it in place because there may be other implementations that
do.  Implementations should likely scan the rtePermInfos list to
determine which operations to allow or deny.

Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqGjJDmUhDSfv-U2qhKJjt9ST7Xh9JXC_irsAQ1TAUsJYg@mail.gmail.com
This commit is contained in:
Alvaro Herrera
2022-12-06 16:09:24 +01:00
parent b5bbaf08ed
commit a61b1f7482
47 changed files with 954 additions and 534 deletions
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27
src/backend/rewrite/rewriteDefine.c
View File

@ -632,14 +632,14 @@ checkRuleResultList(List *targetList, TupleDesc resultDesc, bool isSelect,
/*
* setRuleCheckAsUser
* Recursively scan a query or expression tree and set the checkAsUser
* field to the given userid in all rtable entries.
* field to the given userid in all RTEPermissionInfos of the query.
*
* Note: for a view (ON SELECT rule), the checkAsUser field of the OLD
* RTE entry will be overridden when the view rule is expanded, and the
* checkAsUser field of the NEW entry is irrelevant because that entry's
* requiredPerms bits will always be zero. However, for other types of rules
* it's important to set these fields to match the rule owner. So we just set
* them always.
* RTE entry's RTEPermissionInfo will be overridden when the view rule is
* expanded, and the checkAsUser for the NEW RTE entry's RTEPermissionInfo is
* irrelevant because its requiredPerms bits will always be zero. However, for
* other types of rules it's important to set these fields to match the rule
* owner. So we just set them always.
*/
void
setRuleCheckAsUser(Node *node, Oid userid)
@ -666,18 +666,21 @@ setRuleCheckAsUser_Query(Query *qry, Oid userid)
{
ListCell *l;
/* Set all the RTEs in this query node */
/* Set in all RTEPermissionInfos for this query. */
foreach(l, qry->rteperminfos)
{
RTEPermissionInfo *perminfo = lfirst_node(RTEPermissionInfo, l);
perminfo->checkAsUser = userid;
}
/* Now recurse to any subquery RTEs */
foreach(l, qry->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
if (rte->rtekind == RTE_SUBQUERY)
{
/* Recurse into subquery in FROM */
setRuleCheckAsUser_Query(rte->subquery, userid);
}
else
rte->checkAsUser = userid;
}
/* Recurse into subquery-in-WITH */