Hi, Attempt to revive discussions below... On Wed, Jul 27, 2016 at 07:45:46AM -0700, Jeff Vander Stoep wrote: > When kernel.perf_event_paranoid is set to 3 (or greater), disallow > all access to performance events by users without CAP_SYS_ADMIN. > > This new level of restriction is intended to reduce the attack > surface of the kernel. Perf is a valuable tool for developers but > is generally unnecessary and unused on production systems. Perf may > open up an attack vector to vulnerable device-specific drivers as > recently demonstrated in CVE-2016-0805, CVE-2016-0819, > CVE-2016-0843, CVE-2016-3768, and CVE-2016-3843. This new level of > restriction allows for a safe default to be set on production systems > while leaving a simple means for developers to grant access [1]. > > This feature is derived from CONFIG_GRKERNSEC_PERF_HARDEN by Brad > Spengler. It is based on a patch by Ben Hutchings [2]. Ben's patches > have been modified and split up to address on-list feedback. > > kernel.perf_event_paranoid=3 is the default on both Debian [2] and > Android [3]. While people weren't particularly happy with this global toggle approach, my understanding from face-to-face discussions at LSS2016 was that people were happy with a more scoped restriction (e.g. using capabilities or some other access control mechanism), but no-one had the time to work on that. Does that match everyone's understanding, or am I mistaken? It's also my understanding that for Android, perf_event_paranoid is lowered when the user enables developer mode (rather than only when an external debugger is attached); is that correct? Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
