Compel

Compel temporary GIT repo is at http://github.com/xemul/compel. Now compel sits in the main criu repo at https://github.com/xemul/criu/tree/criu-dev/compel.

Usage ideas

One thing parasite code can do is call clone() and create thread having access to main process VM, FDT, FS, etc. The new thread can then

• Check socket FDs to get stuck/closed by polling them
• Apply "logrotate" on the fly
• Garbage collector
• Catch SIGSEGV, do smth with mappings and act upon "illegal" memory access
  • Remote swap for task
  • WSS detection

Another is to do some activity on the victim and then just unload. With this we can

• Death detection. Open pipe/socket and pass the other end outside. Once the victim dies the pipe/socket will wake up.
• Binary updates. E.g. live patching or libs relink
• Tunneling -- replace opened socket with unix one, and send the former one to the caller
  • Inject socket spy
  • Pack/Unpack
  • Crypt/Decrypt
  • Traffic analyzer
  • Traffic fanout (multiplex)
• The same for files on disks -- proxy via pipe(s)
  • Filter/split logs
• Do "nohup" on the fly
• Debug stuff by MSG_PEEK-ing sockets messages of tee+splice sockets
• Re-connect sleeping sockets to other addresses (not 100% safe)
• "Soft" restart of a service -- call execve() from it's context
• Force entering into CT (except pid namespace, probably)
• Re-open all files (and cwd, root) to facilitate moving on new / (e.g. for disk replacement)
• Remove leaks from e.g. malloc/free heap
• Force reparent (pid change!)
  • Re-open all files -- force daemonize