Installing keyloggers, wrappers and sniffers could not pass unnoticed by file integrity checker I plan to run. What bother me the most is that this grepping /dev/mem stuff works without having to install any additional program or modify an existing one. Possibility for other programs on that machine to malloc() their way to confidential data also gives me shivers. :)

Solution that I'm considering now (since I do not grok Perl guts so well to patch it to do wiping of some "hot variables") is to combine IPC::SharedCache and Tie::EncryptedHash. First one guarantees me that memory won't be freed by system to be used by some other module, and the other one makes it proof for simple grepattack. :) I'll be satisfied with such risk reduction measured by level of costs.

I could easily manage to make program also coredump-proof since memory accessed through IPC::SharedCache continues to live after program dies (or exec($0)'s itself). :) Not that it dumps cores, but sometimes when U're rapidly developing a live system you want to restart the damn thing without many users noticing that.

About the other thing -- userspace FS driver, that would be nice topic for some other thread, but just a few words, I'd like to create virtual filesystem which would be shared through Samba to workstations and would offer personalized view on some highly hierarchically organized application data: imagine: FS explorer as an aplication UI. :)