181146 - Rethink use of TMPDIR in xpcom/io/nsSpecialSystemDirectory.cpp

Status: RESOLVED INCOMPLETE

(Core :: XPCOM, defect)

Description

[tenthumbs]

In typical unix fashion, using TMPDIR may or may not be the wrong thing to 
do depending on which platform you're using.

The BSD crowd uses TMPDIR. That's usually fine but environment variables
are a potential security issue for a setuid program. The SYSV crowd don't
like this so they use the P_tmpdir symbol in stdio.h and ignore TMPDIR.
The glibc people try to do both with mixed results.

Mozilla gets it wrong no matter which way it should go. Using TMPDIR if it
should be using P_tmpdir is almost certainly a platform security issue.
Using any environment variable without check for suid isn't good either.
Pulling random names out of thin air, like TEMP or TMP, and using them is
just asking for trouble.

Obviously it's possible to fix this but I think xpcom is the wrong place 
to do it. Personally, I think all this sort of platform-specific stuff 
belongs in the thing that launches mozilla-bin, then xpcom could just 
check for a known environment variable (or a command line arg, or 
whatever) and just be about it's business.

I don't actually expect anyone to fix this very soon but it _is_ an issue.

Comment 1

[Boris Zbarsky [:bzbarsky]]

As a note, people depend on $TEMP and $TMP to work in the real world (this is
why I added them to the existing $TEMPDIR code).

Comment 2

[tenthumbs]

If you mean bug 176887 then it's a case of one person who thought that TMP and 
TEMP are nice names. If you mean bug 168614 then it's two people who think TMP 
and TEMP are nice.

All of which is irrelevant. On Linux glibc *only* examines TMPDIR. Mozilla 
should honor the platform's standards. In fact mozilla should use library 
calls to deduce the appropriate temp directory to use. It should definitely 
not guess. On a platform that thinks TMPDIR is bad, should mozilla use it 
anyway? I think not. Of course, on such a platform a user probably wouldn't 
define it anyway.

My point is that mozilla shouldn't randomly decide a particular 
object/method/whatever is valid just because it wants to.

And yes I know what I would do but doing it all in xpcom is rather silly.

Comment 3

[Doug Turner (:dougt)]

cc'ing some folk that may have an opinion on this.

Comment 4

[Doug Turner (:dougt)]

lets move this conversation to the newsgroup.  If there is any work required,
this can be the tracking bug.