openssh bugs - Mar 2004 - [Bug 815] RFE: sshd should be able to set environment variables defined by the client

http://bugzilla.mindrot.org/show_bug.cgi?id=815

           Summary: RFE: sshd should be able to set environment variables
                    defined by the client
           Product: Portable OpenSSH
           Version: 3.8p1
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: sshd
        AssignedTo: openssh-bugs at mindrot.org
        ReportedBy: roland.mainz at nrubsig.org


RFE: sshd should be able to set environment variables defined by the client,
e.g. it should be possible that the user defines a value of an environment
variable as part of the "ssh" command-line arguments and
"sshd" then sets that
environment variable for the application to execute.



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------- Additional Comments From djm at mindrot.org  2004-03-21 18:46 -------
If we implement this, we will probably only do it for a couple of environment
variables (LANG and maybe LC_*) as passing arbitrary environment variables
provides new opportunities for a user to break out of restricted shell.



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------- Additional Comments From roland.mainz at nrubsig.org  2004-03-22 00:28
-------
Damien Miller wrote:
> If we implement this, we will probably only do it for a couple of
environment
> variables (LANG and maybe LC_*) as passing arbitrary environment variables
> provides new opportunities for a user to break out of restricted shell.
Good idea. I suggest to add support for filtering name=value pairs via extended
regex pattern - one "accept" pattern and one "reject"
pattern.

Anything which matches the "accept" pattern and doesn't match the
"reject"
pattern should be accepted.

accecpt_pattern should look like this ("match all" for now):
".*=.*"

reject_pattern should look like this (kill linker and ssh env vars... and
DISPLAY since that's used by the X11 forwarding code):
"(^LD.*=.*|^SSH.*=.*|^DISPLAY.*=.*)"

Generally whitelisted should be:
CVSROOT
CVS_RSH
LANG
LC_MESSAGES
LC_TIME
LC_NUMERIC
LC_CTYPE
LC_MONETARY
LC_COLLATE
LC_PAPER
LC_ALL
LPDEST       (used by print spooler to set default printer)
PRINTER      (used by print spooler to set default printer)
PDPRINTER    (used by print spooler to set default printer)
XPRINTER     (used by Xprint - see http://xprint.mozdev.org)
XPSERVERLIST (used by Xprint - see http://xprint.mozdev.org)
TZ           (timezone)
MAIL         (unix mail folder location)



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------- Additional Comments From djm at mindrot.org  2004-03-30 13:58 -------
Created an attachment (id=578)
 --> (http://bugzilla.mindrot.org/attachment.cgi?id=578&action=view)
Implement environment passing

The attached patch implements environment passing for -current. 

ssh gains an option "SendEnv", which specifies which environment
variables may
be sent. sshd gains "AllowEnv", which controls what environment
variables are
accepted (I don't much like this option, it may go away in favour of a fixed
list). 

Both of these options may be specified multiple times (with cumulative results)
and both take basic "*" and "?" wildcards.

This needs testing, especially with non-OpenSSH implementations.




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djm at mindrot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Keywords|                            |patch
            Version|3.8p1                       |-current





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------- Additional Comments From roland.mainz at nrubsig.org  2004-03-31 03:00
-------
Damien Miller wrote:
> ssh gains an option "SendEnv", which specifies which environment
variables may
> be sent. sshd gains "AllowEnv",
What about the explicit "reject" list ?
> which controls what environment variables are
> accepted (I don't much like this option, it may go away in favour of a
fixed
> list).
A hardcoded list may be bad. If someone finds a possible exploit via the
"env-var"-forwarding it may be a good idea to have a quick way for
admins to
block the env var used for that.



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------- Additional Comments From markus at openbsd.org  2004-03-31 06:25 -------
reject lists are bogus.

default should be 'deny'.



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