ggdk1 / fanotify-ecryptfs-test Goto Github PK

This is a simple test program to investigate ecryptfs vs. fanotify.

The program is a 5 thread single-process fanotify 'scanner' set up to cover / and the ecryptfs home
dir under test.

To use:
1. Alter .cpp to set your ecryptfs homedir.
2. Compile using makefile.
3. Run program.
4. Run firefox.
5. Use Firefox.

If Firefox goes grey/gray then you have triggered the problem.
The Scanner output will indicate that 2 threads are blocked in stage 4 - before read(),
they will remain, and the scanner process and Firefox will be stuck in memory.
(Reboot to clear).

I've always seen two threads get stuck (in Firefox and the Scanner), rather than 1 or 3 for example.
This leads me to think there is a dead-lock going on.
Each ecryptfs file access causes two fanotify file events - one for the decrypted file on ecryptfs,
and one for the encrypted file on the host fs.

fanotify can deliver multiple file events in a single read from the fanotify fd, so I wonder if 
each thread is trying to construct events for decrypted files that are waiting for the other thread to complete on the
encrypted files.