> which doesn't help you in a remote code execution exploit inside openssh
To be fair, If it gets to the point where they are executing arbitrary code in the openssh process, your key is already compromised.
SELinux would help with most other causes of key leaks, however.
> The question is, is is possible to use the keys without having them in RAM any more?
In my (albeit limited) experience, no. Even if only because context switching would push the key out of the CPU registers and into RAM if it occurred at the wrong time.
To be fair, If it gets to the point where they are executing arbitrary code in the openssh process, your key is already compromised.
SELinux would help with most other causes of key leaks, however.
> The question is, is is possible to use the keys without having them in RAM any more?
In my (albeit limited) experience, no. Even if only because context switching would push the key out of the CPU registers and into RAM if it occurred at the wrong time.