Created attachment 2497 [details]
Patch disabling uid=0 resetting test on Solaris

After the server process drops uid=0, a test is made to make sure
uid=0 cannot be reclaimed.

On Solaris, if a user is granted ALL privilege in a zone, this user
can successfully call setuid(0) and setgid(0). In this case it is
not due to a failure of dropping uid=0, sshd was started with.
Uid restoration test fails and the user is not permitted to log in.

This fix disables the check on Solaris.
For non-privileged users the inability to reclaim uid=0 is implied
from previous successful call to setresuid().
For user with ALL privilege in the zone the assertion in the test is
not correct; the ability to restore uid=0 stems from additional
privileges granted to the user.

The fix is implemented by replacing appropriate occurrences of
OS-based define HAVE_CYGWIN with functionality-based define
NO_UID_RESTORATION_TEST and defining it for Solaris and Cygwin
in configure.ac.