procfs io and taskstats infoleaks, proc/pid/* threats

(Bringing the subject to the list)

While implementing HARDEN_PROC and arguing with LKML folks about usefullness of the feature, I've discovered /proc/pid/io and taskstats interfaces can be used to gather rather sensitive information, like password length:

http://www.openwall.com/lists/oss-security/2011/06/21/12

The suggested patches:

https://lkml.org/lkml/2011/6/24/88
https://lkml.org/lkml/2011/6/24/89
https://lkml.org/lkml/2011/6/24/91

taskstats patch is partial, it doesn't honor set{u,g}ids and processes using caps. For the full fix ptrace_task_may_access_current() is needed, the patch adding it is pending:

https://lkml.org/lkml/2011/6/20/316
https://lkml.org/lkml/2011/6/20/317

I'd appreciate if somebody points me how information stored in sched, schedstats, stat, and status files can be exploited. I suspect it can be used similar way.

Other thoughts:

Files mountinfo, mounts store information related to the process' fs namespace. I feel this information can be somewhat private, e.g. mount points can reveal private file pathes in case of separate namespaces where this information cannot be learned by reading /proc/self/mountinfo.

Files limits and status store process related restrictions. I dunno whether this can be considered as a private information.

I'd appeciate any comment.

Thanks,

Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments