openssh bugs - Nov 2014 - [Bug 2317] New: sshd_config man page not clear on PermitUserEnvironment

https://bugzilla.mindrot.org/show_bug.cgi?id=2317

            Bug ID: 2317
           Summary: sshd_config man page not clear on
                    PermitUserEnvironment
           Product: Portable OpenSSH
           Version: 6.6p1
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P5
         Component: sshd
          Assignee: unassigned-bugs at mindrot.org
          Reporter: florin at andrei.myip.org
>From the current man page:
PermitUserEnvironment
             Specifies whether ~/.ssh/environment and environmentoptions in
~/.ssh/authorized_keys are processed by sshd(8).  The
default is ?no?.  Enabling environment pro?cessing may enable users to
bypass access restrictions in some configurations using mechanisms such
as LD_PRELOAD.

What that sounds to me like is that enabling that option weakens the
security in general.

But after some googling I came across this discussion:

http://serverfault.com/questions/527638/security-risks-of-permituserenvironment-in-ssh

According to the answer, PermitUserEnvironment only weakens security
for restricted accounts, such as scp-only, etc., but has no impact on
full shell access accounts. If that is correct, then the man page is
incomplete and misleading.

I need that option enabled, but I was hesitant to use it. I almost
decided to not use it, but then I came across that discussion.

Please add a brief note to that entry in the man page, making clear
that there are no security issues with that option if all accounts have
full shell access (of course, assuming my interpretation is correct).

Thanks.

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https://bugzilla.mindrot.org/show_bug.cgi?id=2317

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WONTFIX
             Status|NEW                         |RESOLVED
                 CC|                            |djm at mindrot.org

--- Comment #1 from Damien Miller <djm at mindrot.org> ---
Unfortunately the reality is a little more complex than that.
Restricted accounts may be invoked by the user's shell that may be
affected by environment variables. It's impractical to list all the
possible cases where enabling this has unexpected consequences, so we
leave it to the administrator's discretion and knowledge of their own
system.

I don't see any reason to modify the text to weaken the warning.

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https://bugzilla.mindrot.org/show_bug.cgi?id=2317

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #2 from Damien Miller <djm at mindrot.org> ---
Close all resolved bugs after 7.3p1 release

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