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Re: procmail suid and sendmail

2003-04-04 10:55:41
At 08:27 2003-04-04 -0500, Dave Stern - Former Rocket Scientist did say:
I have a couple of questions. First, why is it a good idea to install
procmail suid?  Isn't this more of a security risk?

There is functionality which cannot be performed if it doesn't have the ability to change uid, notably:

        /etc/procmailrc
                (with elevated privs, discarded when procmail goes to process
                the ~/.procmailrc, or when DROPPRIVS is encountered)
        /etc/procmailrcs/
                (assumes the uid of the file owner)

Both of these facilities are EXTREMELY useful. Also, if you haven't noticed, procmail is rather retentive on checking file permissions - for instance, it doesn't like rcfiles which are group writeable ("suspicious rcfile").

Second, we have the latest sendmail installed sgid with procmail as the
LDA and a systemwide procmailrc everyone runs.  Periodically, I see messages:

   timeout waiting for input from local during Draining Input

Periodically you see these messages WHERE? If in the system log, what service are they attributed to?

Unless you include those details, when you dump the message here, you're either expecting that people have had the same problem as you, or that they'll go searching in the support forums for _another_program_ to find the cause. Given that, the least you could do is specify where the message comes from.

FTR, the FIRST result in deja when searching for the error string as a literal was:

<http://groups.google.com/groups?q=+timeout+waiting+for+input+from+local+during+Draining+Input&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=b4ssv7%24957%241%40mserv2.dl.ac.uk&rnum=1>

There are several other equally applicable messages returned from a direct search on the error message in question.

The error is also mentioned at:
        <http://www.sendmail.org/~ca/email/smenhanced.html>

I'm told I should look at whether the LDA (procmail) is generating too much
output for sendmail. How can I check this? How can I throttle it back if it
is a problem?

Generating 'too much output', eh? Procmail itself shouldn't. You didn't post a procmailrc, or even a hint of it, so we certainly can't give you pointers on what you're doing there.

Perhaps programs called from your procmailrc are emitting a lot of text to stdout. Have you tried running your rules within a sandbox to evaluate what it is they're outputting firsthand?

Related to this, I'm running an older version of procmail, perhaps upgrading
to 3.22 might solve it?

'an older verison of procmail'? Such as? I didn't see the version mentioned anywhere in your post.

If you have security concerns about procmail (as expressed at the top of your post), keeping on top of the revision history for it might be a good idea in any event.

---
 Sean B. Straw / Professional Software Engineering

 Procmail disclaimer: <http://www.professional.org/procmail/disclaimer.html>
 Please DO NOT carbon me on list replies.  I'll get my copy from the list.


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