On 12/11/2019 12:36 PM, Andi Kleen wrote: >>> In this circumstances CAP_SYS_PERFMON looks like smart balanced advancement that >>> trade-offs between perf_events subsystem extensions, required level of control >>> and configurability of perf_events, existing users adoption effort, and it brings >>> security hardening benefits of decreasing attack surface for the existing users >>> and use cases. >> I'm not 100% opposed to CAP_SYS_PERFMON. I am 100% opposed to new capabilities >> that have a single use. Surely there are other CAP_SYS_ADMIN users that [cs]ould >> be converted to CAP_SYS_PERFMON as well. If there is a class of system performance >> privileged operations, say a dozen or so, you may have a viable argument. > perf events is not a single use. If it is only being called in two places, it is single use. > It has a bazillion of sub functionalities, > including hardware tracing, software tracing, pmu counters, software counters, > uncore counters, break points and various other stuff in its PMU drivers. > > See it more as a whole quite heterogenous driver subsystem. > > I guess CAP_SYS_PERFMON is not a good name because perf is much more > than just Perfmon. Perhaps call it CAP_SYS_PERF_EVENTS > > -Andi
