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bpf: Add bpf_current_task_under_cgroup helper

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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 <sargun@sargun.me>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sargun Dhillon 2016-08-12 08:56:52 -07:00 committed by David S. Miller
parent aed704b7a6
commit 60d20f9195
4 changed files with 45 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/uapi/linux/bpf.h
View File

@ -375,6 +375,17 @@ enum bpf_func_id {
*/
BPF_FUNC_probe_write_user,
/**
* bpf_current_task_under_cgroup(map, index) - Check cgroup2 membership of current task
* @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
* @index: index of the cgroup in the bpf_map
* Return:
* == 0 current failed the cgroup2 descendant test
* == 1 current succeeded the cgroup2 descendant test
* < 0 error
*/
BPF_FUNC_current_task_under_cgroup,
__BPF_FUNC_MAX_ID,
};

2
kernel/bpf/arraymap.c
View File

@ -538,7 +538,7 @@ static int __init register_perf_event_array_map(void)
}
late_initcall(register_perf_event_array_map);
#ifdef CONFIG_SOCK_CGROUP_DATA
#ifdef CONFIG_CGROUPS
static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
struct file *map_file /* not used */,
int fd)

4
kernel/bpf/verifier.c
View File

@ -1053,7 +1053,8 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
goto error;
break;
case BPF_MAP_TYPE_CGROUP_ARRAY:
if (func_id != BPF_FUNC_skb_in_cgroup)
if (func_id != BPF_FUNC_skb_in_cgroup &&
func_id != BPF_FUNC_current_task_under_cgroup)
goto error;
break;
default:
@ -1075,6 +1076,7 @@ static int check_map_func_compatibility(struct bpf_map *map, int func_id)
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
goto error;
break;
case BPF_FUNC_current_task_under_cgroup:
case BPF_FUNC_skb_in_cgroup:
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
goto error;

30
kernel/trace/bpf_trace.c
View File

@ -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;
}