[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: tar deletes symlink on extract (fwd)

---------- Forwarded message ----------
Received: from alcor.twinsun.com ([])
	by yakko.doogie.org with esmtp (Exim 3.12 #1 (Debian))
	id 12lhBU-0000O3-00
	for <adam@doogie.org>; Sat, 29 Apr 2000 19:02:04 -0500
Received: from green-office.twinsun.com ([]) by
    alcor.twinsun.com (8.9.3/8.9.3) with ESMTP id RAA20041; Sat,
     29 Apr 2000 17:00:30 -0700 (PDT)
Received: (eggert@localhost) by green-office.twinsun.com (8.9.3+Sun/8.9.3)
    id RAA03895; Sat, 29 Apr 2000 17:00:30 -0700 (PDT)
Date: Sat, 29 Apr 2000 17:00:30 -0700 (PDT)
From: Paul Eggert <eggert@twinsun.com>
Message-Id: <200004300000.RAA03895@green-office.twinsun.com>
To: bdale@gag.com
CC: bug-tar@gnu.org, 63161-forwarded@bugs.debian.org, adam@doogie.org
In-reply-to: <20000429230237.9A96C1EA73@rover.gag.com> (bdale@gag.com)
Subject: Re: tar deletes symlink on extract
References:  <20000429230237.9A96C1EA73@rover.gag.com>

   Date: Thu, 27 Apr 2000 12:34:55 -0500 (CDT)
   From: Adam Heath <adam@doogie.org>

   It changed the symlink to a dir, and broke my system.
   Granted, this is easy to fix, but this is very bad.

tar's behavior is needed to avoid a security bug where an intruder
plants a symbolic link to a victim file just before root (or some
other user) uses tar to extract a file with the same name as the
victim file.  tar can't tell the difference between your
/usr->mount/usr symlink and an intruder's symlink.

Sorry about the behavior change, but I couldn't see any other way to
plug the security hole.  The security hole is apparently a real
problem in practice: I've gotten multiple bug reports about it, and am
still getting reports about older versions.

To work around the problem, use the --overwrite option of tar 1.13.16
or later; this restores the old, insecure behavior.  For more details,
please see tar's NEWS file.

Reply to: