[exim-dev] [Bug 1684] Malformed headers which exceed length …

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Author: admin
Date:  
To: exim-dev
Old-Topics: [exim-dev] [Bug 1684] New: Malformed headers which exceed length spec willingly passed to remote servers
Subject: [exim-dev] [Bug 1684] Malformed headers which exceed length spec willingly passed to remote servers
https://bugs.exim.org/show_bug.cgi?id=1684

Andreas Metzler <eximusers@???> changed:

           What    |Removed                     |Added
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                 CC|                            |eximusers@???


--- Comment #10 from Andreas Metzler <eximusers@???> ---
(In reply to Jeremy Harris from comment #6)
> $max_received_linelength is already populated with the relevant value.
> This can be checked in the smtp_data acl and the smtp transports:

[...]
> remote_smtp:
> driver = smtp
> message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}}
>
> Doing the latter results in a bounce for a long-line message accepted via
> non-smtp and routed to an smtp transport. You could reject in the non-smtp
> acl instead, but if support for long-lines in non-smtp traffic is desired
> this would be complex to properly filter.
>
> Possibly we should add the above to the example configuration file.


The problem with this approach is that bounce message generated when rejecting
SMTP transmission of a pipe injected message ("/usr/sbin/sendmail
somebkdy@??? < longlines.txt") is lacking any information why the
message bounced.

[-- Typ: text/plain, Kodierung: 7bit, Größe: 0,2K --]

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

recip@???

[-- Anhang #2 --]
[-- Typ: message/delivery-status, Kodierung: 7bit, Größe: 0,1K --]

Reporting-MTA: dns; server.example.com

Action: failed
Final-Recipient: rfc822;recip@???
Status: 5.0.0

[-- Anhang #3 --]
[-- Typ: text/rfc822-headers, Kodierung: 7bit, Größe: 0,4K --]

Return-path: <root@???>
Received: from ametzler by server.example.com with local (Exim 4.88)
        (envelope-from <root@???>)
        id 1cNNWo-0005bq-H4
        for recip@???; Sat, 31 Dec 2016 18:33:10 +0100
Message-Id: <E1cNNWo-0005bq-H4@???>
From: Andreas Metzler <sender@???>
Date: Sat, 31 Dec 2016 18:33:10 +0100
X-Exim-DSN-Information: Due to administrative limits only headers are returned


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