patch to send incoming key to AuthorizedKeysCommand via stdin

Eldon Koyle esk-openssh at
Sat Mar 22 03:38:42 EST 2014

On  Mar 20 16:17-0400, Daniel Kahn Gillmor wrote:
> On 03/20/2014 03:58 PM, Scott Duckworth wrote:
> > The patches for different openssh versions can be found at
> >  The file
> > describes some caveats, including the possibility for deadlock if the
> > command specified with AuthorizedKeysCommand does not fully consume or
> > close its standard input.
> This is worrisome.  sshd itself shouldn't be adversely affected by
> subcommand failing to process the data in any way.  Do you see any way
> to make sshd more robust in this case?  (e.g. what if the key was
> provided as another command line parameter instead of stdin)

Would it be reasonable to add another configuration option to specify
that you want to send the key via stdin to the AuthorizedKeysCommand,
and have it default to no/false?  This should be enough to prevent
breakage of existing implementations while still allowing the new and
useful functionality.

Eldon Koyle
... Logically incoherent, semantically incomprehensible, and legally ...

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