From 60d20f9195b260bdf0ac10c275ae9f6016f9c069 Mon Sep 17 00:00:00 2001 From: Sargun Dhillon Date: Fri, 12 Aug 2016 08:56:52 -0700 Subject: bpf: Add bpf_current_task_under_cgroup helper This adds a bpf helper that's similar to the skb_in_cgroup helper to check whether the probe is currently executing in the context of a specific subset of the cgroupsv2 hierarchy. It does this based on membership test for a cgroup arraymap. It is invalid to call this in an interrupt, and it'll return an error. The helper is primarily to be used in debugging activities for containers, where you may have multiple programs running in a given top-level "container". Signed-off-by: Sargun Dhillon Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Tejun Heo Acked-by: Tejun Heo Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/trace/bpf_trace.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index b20438fdb029..6b794d6669a7 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -376,6 +376,34 @@ static const struct bpf_func_proto bpf_get_current_task_proto = { .ret_type = RET_INTEGER, }; +static u64 bpf_current_task_under_cgroup(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) +{ + struct bpf_map *map = (struct bpf_map *)(long)r1; + struct bpf_array *array = container_of(map, struct bpf_array, map); + struct cgroup *cgrp; + u32 idx = (u32)r2; + + if (unlikely(in_interrupt())) + return -EINVAL; + + if (unlikely(idx >= array->map.max_entries)) + return -E2BIG; + + cgrp = READ_ONCE(array->ptrs[idx]); + if (unlikely(!cgrp)) + return -EAGAIN; + + return task_under_cgroup_hierarchy(current, cgrp); +} + +static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = { + .func = bpf_current_task_under_cgroup, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_CONST_MAP_PTR, + .arg2_type = ARG_ANYTHING, +}; + static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) { switch (func_id) { @@ -407,6 +435,8 @@ static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) return &bpf_perf_event_read_proto; case BPF_FUNC_probe_write_user: return bpf_get_probe_write_proto(); + case BPF_FUNC_current_task_under_cgroup: + return &bpf_current_task_under_cgroup_proto; default: return NULL; } -- cgit v1.2.3