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From: aland@informix.com (Colonel Panic)
Newsgroups: comp.databases
Subject: Re: Informix queries: raw partitions, price support
Summary: the raw and the cooked
Message-ID: <1991Apr30.050635.5254@informix.com>
Date: 30 Apr 91 05:06:35 GMT
References: <461@octelb.octel.UUCP> <1991Apr26.150939.2069@odi.com>
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In article <1991Apr26.150939.2069@odi.com> dlw@odi.com writes:
>In article <461@octelb.octel.UUCP> jfd@octel.UUCP (John F. Detke) writes:
>	   Informix wants to chmod and chgrp informix /dev/rsd0d
>   in order to use raw partitions. Why the heck do they have set-uid root programs
>   then? The DBA wants the speed improvements, but I am reluctant to open up /dev
>   like this. Am I being too paranoid? 
>
>I don't think I understand.  Informix needs for their Unix process to
>be able to access /dev/rsd0d.  They are saying that you should chmod
>it to something, and chown it to "informix", in order to grant access
>to their process.  It seems that you are saying that you don't like
>the idea of doing this, because it would "open up /dev", implying that
>this would create a possible security problem.  Instead you are
>counter-proposing that they make their program a "setuid root"
>program.

The engines are already setuid for the following purposes:
    1) boost ulimit up to an arbitrarily high value
    2) set groupid to informix
After doing so, real and effective uids are set back to those of the 
invoking user (hence the need to have the devices read/writeable by 
group informix).

>If I were paranoid, I might be more worried about letter their process
>run as "root" than about setting the access on /dev/rsd0d as they
>recommend.  Setting the access will only let their process access that
>device, and not others; making their program run as "root" will let
>their process access any device whatsoever.  Why would it be more secure
>for them to run as "root"?

Perhaps Mr. Detke is concerned that this would allow an Informix
process to run rampant over his devices.  As long as /dev is
read/search only for non-root uids, I don't see a problem.

Also, this is a good time to bring this up.  As a safeguard against
media failure, it's always best to use a logical pathname rather
than the actual device path.  We recommend assigning logical names
to each slice to be used by OnLine by building hard links.  In the
above case, if the following is done:

    cd /dev 
    ln rsd0d online_1
    chown informix online_1
    chgrp informix online_1
    chmod 660 online_1

and /dev/online_1 is used in the OnLine configuration screen (and
tbconfig file), it makes recovery easier.  If Disk 0 were to fail,
you could reassign another slice of equal or greater size and restore 
to the new slice:

    cd /dev 
    rm online_1
    ln rsd2d online_1
    chown informix online_1
    chgrp informix online_1
    chmod 660 online_1

Then, just reinitialize, restore, and you don't have to rely on that
particular device being available.

--
Alan Denney      aland@informix.com      {pyramid|uunet}!infmx!aland

"The biggest problem with baseball today is the money being thrown
around.  The players aren't in the sport for the joy of the game
anymore, they're in it for the money.  Greed is ruining baseball."
     - Rogers Hornsby (when Cincinatti Reds manager), 1953