From 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Tue, 28 Jun 2022 10:43:06 -0700 Subject: bpf: per-cgroup lsm flavor Allow attaching to lsm hooks in the cgroup context. Attaching to per-cgroup LSM works exactly like attaching to other per-cgroup hooks. New BPF_LSM_CGROUP is added to trigger new mode; the actual lsm hook we attach to is signaled via existing attach_btf_id. For the hooks that have 'struct socket' or 'struct sock' as its first argument, we use the cgroup associated with that socket. For the rest, we use 'current' cgroup (this is all on default hierarchy == v2 only). Note that for some hooks that work on 'struct sock' we still take the cgroup from 'current' because some of them work on the socket that hasn't been properly initialized yet. Behind the scenes, we allocate a shim program that is attached to the trampoline and runs cgroup effective BPF programs array. This shim has some rudimentary ref counting and can be shared between several programs attaching to the same lsm hook from different cgroups. Note that this patch bloats cgroup size because we add 211 cgroup_bpf_attach_type(s) for simplicity sake. This will be addressed in the subsequent patch. Also note that we only add non-sleepable flavor for now. To enable sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu, shim programs have to be freed via trace rcu, cgroup_bpf.effective should be also trace-rcu-managed + maybe some other changes that I'm not aware of. Reviewed-by: Martin KaFai Lau Signed-off-by: Stanislav Fomichev Link: https://lore.kernel.org/r/20220628174314.1216643-4-sdf@google.com Signed-off-by: Alexei Starovoitov --- tools/include/uapi/linux/bpf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/include/uapi/linux/bpf.h') diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e81362891596..b7479898c879 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -998,6 +998,7 @@ enum bpf_attach_type { BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, BPF_PERF_EVENT, BPF_TRACE_KPROBE_MULTI, + BPF_LSM_CGROUP, __MAX_BPF_ATTACH_TYPE }; -- cgit v1.2.3-59-g8ed1b