restrict statistics information to user

taskstats and /proc/PID/io may be used for gathering private information. E.g. for openssh and vsftpd daemons wchars/rchars may be used to learn the precise password length (pass_len = w_chars - CONST). Restrict it to user.

The simplified proof learning whether ~*/.ssh/authorized_keys file exists is posted here:
http://www.openwall.com/lists/oss-security/2011/06/21/12

Vasiliy Kulikov (2):
proc: restrict access to /proc/PID/io
taskstats: restrict access to user

 fs/proc/base.c     |    7 +++++--
 kernel/taskstats.c |   23 ++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)