OpenSSh privilege separation model - http://www.citi.umich.edu/u/provos/ssh/privsep.html
Posix_spawn is implemented in POSIX adapter as an alternative to fork() that is heavily used in Privilege separation.
Additional state info is added to sshd to accommodate distinguishing the various modes (privileged monitor, unprivileged child, authenticated child).
Required service state (like config and host keys) is transmitted over pipes from monitor to child processes.
Changes to installation scripts and tests to accomodate new architectural changes
client now connect to ssh-agent at Identification level, preventing rogue processes hosting "ssh-agent" pipes from impersonating and elevating to client context.
Since ssh-agent now cannot do ImpersonateNamedpipeClient, retrieve the client impersonation token explicitly and rely on ImpersonateLoggedonUser instead.
https://github.com/PowerShell/Win32-OpenSSH/issues/479https://github.com/PowerShell/Win32-OpenSSH/issues/476https://github.com/PowerShell/Win32-OpenSSH/issues/474https://github.com/PowerShell/Win32-OpenSSH/issues/467
bug #479 - "ls c:" is not working
sanitized_path() is modified to handle the edge case "\x:"
2.bug #476 - "cd c:" is not working
If "c:" is passed to _fullpath() then it is returning existing path but not "c:", so if we append "\" to "c:" then it is working fine.
3.bug #474 - code cleanup MAX_PATH
Using PATH_MAX variable instead of MAX_PATH
In dirent.h, used PATH_MAX instead of hardcoding 256 characters
In readdir(), changed the pdirentry to be a static variable. Before this, we are leaking the memory.
4.bug #467 - SFTP rename failed if the newpath already exists.
The _wrename throws error if the newpath exists.
To make it consistent with the linux behavrior,
a) if the newpath is a file and if it exists then delete it so that _wrename will succeed.
b) if the newpath is a directory and if it is empty then delete it so that _wrename will succeed.
