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Install a data-type-based solution for protecting pg_get_expr().

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Since the code underlying pg_get_expr() is not secure against malformed
input, and can't practically be made so, we need to prevent miscreants
from feeding arbitrary data to it.  We can do this securely by declaring
pg_get_expr() to take a new datatype "pg_node_tree" and declaring the
system catalog columns that hold nodeToString output to be of that type.
There is no way at SQL level to create a non-null value of type pg_node_tree.
Since the backend-internal operations that fill those catalog columns
operate below the SQL level, they are oblivious to the datatype relabeling
and don't need any changes.
This commit is contained in:
Tom Lane
2010-09-03 01:34:55 +00:00
parent 8ab6a6b456
commit 303696c3b4
19 changed files with 149 additions and 62 deletions
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57
src/backend/utils/adt/pseudotypes.c
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@@ -16,7 +16,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/pseudotypes.c,v 1.23 2010/01/02 16:57:55 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/pseudotypes.c,v 1.24 2010/09/03 01:34:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -398,3 +398,58 @@ shell_out(PG_FUNCTION_ARGS)
PG_RETURN_VOID(); /* keep compiler quiet */
}
/*
* pg_node_tree_in - input routine for type PG_NODE_TREE.
*
* pg_node_tree isn't really a pseudotype --- it's real enough to be a table
* column --- but it presently has no operations of its own, and disallows
* input too, so its I/O functions seem to fit here as much as anywhere.
*/
Datum
pg_node_tree_in(PG_FUNCTION_ARGS)
{
/*
* We disallow input of pg_node_tree values because the SQL functions that
* operate on the type are not secure against malformed input.
*/
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot accept a value of type pg_node_tree")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
/*
* pg_node_tree_out - output routine for type PG_NODE_TREE.
*
* The internal representation is the same as TEXT, so just pass it off.
*/
Datum
pg_node_tree_out(PG_FUNCTION_ARGS)
{
return textout(fcinfo);
}
/*
* pg_node_tree_recv - binary input routine for type PG_NODE_TREE.
*/
Datum
pg_node_tree_recv(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot accept a value of type pg_node_tree")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
/*
* pg_node_tree_send - binary output routine for type PG_NODE_TREE.
*/
Datum
pg_node_tree_send(PG_FUNCTION_ARGS)
{
return textsend(fcinfo);
}