libvmem

[Erwin Tsaur]

Does anybody know in the libvmem libraries what happens to the data after a powercycle?

Basically, if the DIMM is not encrypted will the data be accessible by others?

What mechanism makes the temporary files 'volatile' and secure?

Thanks,
Erwin

[Andy Rudoff]

Hi Erwin,

The answer is the same as for temporary files on traditional storage.  In other words, if I create a temporary file, fill it with data, and then delete it, the data is still sitting in blocks in the file system free list, but of course those blocks are initialized before they are allocated to any new files, so applications cannot access the old data.  However, kernel code or root processes looking directly at the raw device could see the old data.

libvmem works the same way, using the same method as the POSIX tmpfile(3) library call where the temporary file is created and then unlinked so that the blocks go back to the free list when the application exits or if the system crashes.  So security is provided by the file system just as it is when any file is deleted.

Hope that helps,

-andy