Thread: Minor changed needed to doc on untrusted pl/perl example
I know this is minor but we all long for perfection.:)
The current doc shows
The current doc shows
37.5. Trusted and Untrusted PL/Perl
Normally, PL/Perl is installed as a "trusted" programming language named plperl. In this setup, certain Perl operations are disabled to preserve security. In general, the operations that are restricted are those that interact with the environment. This includes file handle operations, require, and use (for external modules). There is no way to access internals of the database server process or to gain OS-level access with the permissions of the server process, as a C function can do. Thus, any unprivileged database user may be permitted to use this language.
Here is an example of a function that will not work because file system operations are not allowed for security reasons:
CREATE FUNCTION badfunc() RETURNS integer AS $$
open(TEMP, ">/tmp/badfile");
print TEMP "Gotcha!\n";
return 1;
$$ LANGUAGE plperl;
I believe the code snippet should look like this for it to work correctly:
CREATE FUNCTION badfunc() RETURNS integer AS $$
open(TEMP, ">/tmp/badfile");
print TEMP "Gotcha!\n";
close(TEMP);
return 1;
$$ LANGUAGE plperl;
On Fri, Oct 21, 2005 at 01:06:05PM -0500, Bob wrote: > CREATE FUNCTION badfunc() RETURNS integer AS $$ > open(TEMP, ">/tmp/badfile"); > print TEMP "Gotcha!\n"; > return 1; > $$ LANGUAGE plperl; > > I believe the code snippet should look like this for it to work correctly: > > CREATE FUNCTION badfunc() RETURNS integer AS $$ > open(TEMP, ">/tmp/badfile"); > print TEMP "Gotcha!\n"; > close(TEMP); > return 1; > $$ LANGUAGE plperl; The function should work without an explicit close (or it would, but for the security check). The file should appear on disk immediately after the open, although the data might not be flushed to disk until the file is actually closed, such as when the calling session's postmaster exits (that's how a plperlu version behaves on my test system, anyway). Not that I disagree with adding an explicit close, but the example should still "work" without it. -- Michael Fuhr