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Date:      Sun, 05 Oct 2014 20:53:21 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-ports-bugs@FreeBSD.org
Subject:   [Bug 123468] mail/postgrey: information leak, privacy issue
Message-ID:  <bug-123468-13-jFdXOOFnKy@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-123468-13@https.bugs.freebsd.org/bugzilla/>
References:  <bug-123468-13@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=123468

--- Comment #12 from marquis@roble.com ---
> - If the operator of %r uses the default response string from postgrey

It appears that you're mistaking %r with the localhost (running freebsd
and postgrey).  %r is generated on the mailserver running postgrey and is
sent A) to the originating MTA via SMTP handshake and B) if the message
is timed-out it is normally sent back to the originating user in the
bounce message text.

> they are making it public they're using postgrey. If they didn't want to
> disclose that, they'd override the string and remove the URI entirely.

It's not clear what you are referring to here.  First the postgrey
advertisement is not at issue.  WRT removing it, the only way to do so is
by editing the postgrey script on the recipient MTA.  The installation
Makefile does not provide any mechanism for "override"ing %r nor does the
sender or sending MTA have any way to do this.  More importantly, none of
these parties has expressed an interest in providing the owner of
postgrey.schweikert.ch with this information.

> - Network information about the server receiving for %r is not disclosed to
> postgrey.schweikert.ch.

True in some cases but not relevant to the patch.  If the recipient of a
bounced message or the reader of a mail log follows the URL, for
information on greylisting for example, the operator of
postgrey.schweikert.ch is informed of the sender's domain.  This is what
the patch prevents.  The owner of schweikert.ch does not need to know
what remote MTAs are being greylisted by other's MTAs nor is the
disclosed domain name in any way helpful in researching the cause of a
bounced or delayed email.

The bottom line is this: neither the mail sender nor the intermediate MTA
operators have an interest in disclosing this information to a third
party (postgrey.schweikert.ch).

> - The IP address disclosed to the postgrey.schweikert.ch is that of the browser
> going to the site, not the mail server relaying to %r.

This is incorrect.  The %r string in question is the providing the
sender's domainname.  It has nothing to do with web browsers.

> The information disclosure is that a browser appearing at a given IP address is
> emitting unencrypted HTTP requests which may or may not be associated with an
> email sent to %r.  The lack of SSL and minimal level of information provided
> means this is effectively a disclosure of information already widely disclosed.

I respect your opinion that the information disclosed is "minimal",
however, it is nevertheless just your opinion.  Many of us believe that
privacy does matter (as the popularity of Edward Snowden has revealed
much less the work of groups from the EFF to EPIC).  The patch would not
have been submitted if everyone held the same opinion.

> Given the insignificant nature of the disclosure, there is greater utility
> in not deviating from upstream.

An opinion of what constitutes privacy and a mistaken evaluation of what
postgrey's %r string resolves to are not valid criteria for rejecting the
patch.  

This patch should be evaluated on more factual and policy-based criteria.

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