On Fri, 2017-08-25 at 11:01 -0700, Jeffrey Vander Stoep via Selinux wrote: > I’d like to get your thoughts on adding LSM permission checks on BPF > objects. > > By default, the ability to create and use eBPF maps/programs requires > CAP_SYS_ADMIN [1]. Alternatively, all processes can be granted access > to bpf() functions. This seems like poor granularity. [2] > > Like files and sockets, eBPF maps and programs can be passed between > processes by FD and have a number of functions that map cleanly to > permissions. > > Let me know what you think. Are there simpler alternative approaches > that we haven’t considered?
Is it possible to create the map/program in one process (with CAP_SYS_ADMIN), pass the resulting fd to netd, and then use it there (without requiring CAP_SYS_ADMIN in netd itself)? What level of granularity would be useful? Would it go beyond just being able to use bpf() at all? > > Thanks! > Jeff > > [1] http://man7.org/linux/man-pages/man2/bpf.2.html NOTES section > [2] We are considering eBPF for network filtering by netd. Giving > netd > CAP_SYS_ADMIN would considerably increase netd’s privileges. > Alternatively allowing all processes permission to use bpf() goes > against the principle of least privilege exposing a lot of kernel > attack surface to processes that do not actually need it. >
