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Postings from October 2003
In article <20031027160008.3b3377b_.rgarciasuarez@_ree._r>,
Rafael Garcia-Suarez <rgarciasuarez@free.fr> writes:
> Ton Hospel wrote:
>>
>> If I understand correctly, the croak happens not on the localization
>> of ENV, but when the system() tries to use it ?
>
> Yes. I added the check for aliased *ENV in the same routine that
> checks for insecure $ENV{XYZ}. (It's thus only called with taint
> checks turned on.)
Perfect.
>
>> That sounds fine for my library. It fixes the security hole, I can still
>> fool CGI.pm with a fake env, and if the user tries to do a
>> system/exec/qr during that time, he will get an error (I wasn't too sure
>> about the proper behaviour for that last case anyways. The real PATH
>> etc. will in fact have been set to safe values, but the user maybe
>> expected his $ENV{PATH}=... to actually do something)
>
> Why do you want to alias *ENV by the way ?
> You could have done
> local %ENV = (k1 => v1, ...);
> or
> local %ENV = %ENV;
> $ENV{k1} = v1; ...
It's an event driven setup to run many CGI's in parallel and it is meant
to be *FAST*. There is one fake environment hash reference per
connection object. Now if the corresponding input stream comes in in
many parts (consider many pending slow connections, or big fileuploads),
I will call the event handler many times, each time needing to switch in
about 40 environment variables. That's not only 40 useless calls to
setenv, but even worse, a lot of system calls.
Observe:
strace perl -Twe 'local %ENV = (PATH =>"/a:/b:/c:/d:/e:/f")'
....
stat64("/a", 0xbfffea9c) = -1 ENOENT (No such file or directory)
stat64("/b", 0xbfffea9c) = -1 ENOENT (No such file or directory)
stat64("/c", 0xbfffea9c) = -1 ENOENT (No such file or directory)
stat64("/d", 0xbfffea9c) = -1 ENOENT (No such file or directory)
stat64("/e", 0xbfffea9c) = -1 ENOENT (No such file or directory)
stat64("/f", 0xbfffea9c) = -1 ENOENT (No such file or directory)
.....
(there's also such a massive check for the original path on startup,
but I don't care about that, it's a persistent server)
Versus:
strace perl -Twe 'local *ENV = {PATH =>"/a:/b:/c:/d:/e:/f"}'
....
no stat calls on my new path (and no setenv calls)
....
So simply doing:
sub io_readevent_callback {
my $connection = shift;
local *ENV = $connection->{env};
....
}
makes things a lot faster.
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