UBUNTU: SAUCE: security,perf: Allow further restriction of perf_event_open
https://lkml.org/lkml/2016/1/11/587
The GRKERNSEC_PERF_HARDEN feature extracted from grsecurity. Adds the
option to disable perf_event_open() entirely for unprivileged users.
This standalone version doesn't include making the variable read-only
(or renaming it).
When kernel.perf_event_open is set to 3 (or greater), disallow all
access to performance events by users without CAP_SYS_ADMIN.
Add a Kconfig symbol CONFIG_SECURITY_PERF_EVENTS_RESTRICT that
makes this value the default.
This is based on a similar feature in grsecurity
(CONFIG_GRKERNSEC_PERF_HARDEN). This version doesn't include making
the variable read-only. It also allows enabling further restriction
at run-time regardless of whether the default is changed.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Tim Gardner <tim.gardner@canonical.com>