Commit bf6fa2c8 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

bpf: implement bpf_get_current_cgroup_id() helper 



bpf has been used extensively for tracing. For example, bcc
contains an almost full set of bpf-based tools to trace kernel
and user functions/events. Most tracing tools are currently
either filtered based on pid or system-wide.

Containers have been used quite extensively in industry and
cgroup is often used together to provide resource isolation
and protection. Several processes may run inside the same
container. It is often desirable to get container-level tracing
results as well, e.g. syscall count, function count, I/O
activity, etc.

This patch implements a new helper, bpf_get_current_cgroup_id(),
which will return cgroup id based on the cgroup within which
the current task is running.

The later patch will provide an example to show that
userspace can get the same cgroup id so it could
configure a filter or policy in the bpf program based on
task cgroup id.

The helper is currently implemented for tracing. It can
be added to other program types as well when needed.

Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent ea9916ea

include/linux/bpf.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -746,6 +746,7 @@ extern const struct bpf_func_proto bpf_get_stackid_proto; 
extern const struct bpf_func_proto bpf_get_stack_proto;

extern const struct bpf_func_proto bpf_get_stack_proto;

extern const struct bpf_func_proto bpf_sock_map_update_proto;

extern const struct bpf_func_proto bpf_sock_map_update_proto;

extern const struct bpf_func_proto bpf_sock_hash_update_proto;

extern const struct bpf_func_proto bpf_sock_hash_update_proto;

extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;





/* Shared helpers among cBPF and eBPF. */

/* Shared helpers among cBPF and eBPF. */

void bpf_user_rnd_init_once(void);

void bpf_user_rnd_init_once(void);

include/uapi/linux/bpf.h

+7 −1
Original line number Original line Diff line number Diff line
@@ -2070,6 +2070,11 @@ union bpf_attr { 
 * 		**CONFIG_SOCK_CGROUP_DATA** configuration option.

 * 		**CONFIG_SOCK_CGROUP_DATA** configuration option.

 * 	Return

 * 	Return

 * 		The id is returned or 0 in case the id could not be retrieved.

 * 		The id is returned or 0 in case the id could not be retrieved.

 *

 * u64 bpf_get_current_cgroup_id(void)

 * 	Return

 * 		A 64-bit integer containing the current cgroup id based

 * 		on the cgroup within which the current task is running.

 */

 */

#define __BPF_FUNC_MAPPER(FN)		\

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\

	FN(unspec),			\
@@ -2151,7 +2156,8 @@ union bpf_attr { 
	FN(lwt_seg6_action),		\

	FN(lwt_seg6_action),		\

	FN(rc_repeat),			\

	FN(rc_repeat),			\

	FN(rc_keydown),			\

	FN(rc_keydown),			\

	FN(skb_cgroup_id),

	FN(skb_cgroup_id),		\

	FN(get_current_cgroup_id),





/* integer value in 'imm' field of BPF_CALL instruction selects which helper

/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call

 * function eBPF program intends to call

kernel/bpf/core.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -1765,6 +1765,7 @@ const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak; 
const struct bpf_func_proto bpf_get_current_comm_proto __weak;

const struct bpf_func_proto bpf_get_current_comm_proto __weak;

const struct bpf_func_proto bpf_sock_map_update_proto __weak;

const struct bpf_func_proto bpf_sock_map_update_proto __weak;

const struct bpf_func_proto bpf_sock_hash_update_proto __weak;

const struct bpf_func_proto bpf_sock_hash_update_proto __weak;

const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;





const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)

const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)

{

{

kernel/bpf/helpers.c

+15 −0
Original line number Original line Diff line number Diff line
@@ -179,3 +179,18 @@ const struct bpf_func_proto bpf_get_current_comm_proto = { 
	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,

	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,

	.arg2_type	= ARG_CONST_SIZE,

	.arg2_type	= ARG_CONST_SIZE,

};

};



#ifdef CONFIG_CGROUPS

BPF_CALL_0(bpf_get_current_cgroup_id)

{

	struct cgroup *cgrp = task_dfl_cgroup(current);



	return cgrp->kn->id.id;

}



const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {

	.func		= bpf_get_current_cgroup_id,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

};

#endif

kernel/trace/bpf_trace.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -564,6 +564,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_get_prandom_u32_proto;

		return &bpf_get_prandom_u32_proto;

	case BPF_FUNC_probe_read_str:

	case BPF_FUNC_probe_read_str:

		return &bpf_probe_read_str_proto;

		return &bpf_probe_read_str_proto;

	case BPF_FUNC_get_current_cgroup_id:

		return &bpf_get_current_cgroup_id_proto;

	default:

	default:

		return NULL;

		return NULL;

	}

	}

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