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Commit 6acc5c29 authored by Chenbo Feng's avatar Chenbo Feng Committed by David S. Miller
Browse files

Add a eBPF helper function to retrieve socket uid 



Returns the owner uid of the socket inside a sk_buff. This is useful to
perform per-UID accounting of network traffic or per-UID packet
filtering. The socket need to be a fullsock otherwise overflowuid is
returned.

Signed-off-by: default avatarChenbo Feng <fengc@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 91b8270f

include/uapi/linux/bpf.h

+8 −1
Original line number Diff line number Diff line
@@ -465,6 +465,12 @@ union bpf_attr { 
 *     @skb: pointer to skb

 *     Return: 8 Bytes non-decreasing number on success or 0 if the socket

 *     field is missing inside sk_buff

 *

 * u32 bpf_get_socket_uid(skb)

 *     Get the owner uid of the socket stored inside sk_buff.

 *     @skb: pointer to skb

 *     Return: uid of the socket owner on success or 0 if the socket pointer

 *     inside sk_buff is NULL

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -513,7 +519,8 @@ union bpf_attr { 
	FN(skb_change_head),		\

	FN(xdp_adjust_head),		\

	FN(probe_read_str),		\

	FN(get_socket_cookie),

	FN(get_socket_cookie),		\

	FN(get_socket_uid),



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

 * function eBPF program intends to call

net/core/filter.c

+22 −0
Original line number Diff line number Diff line
@@ -2619,6 +2619,24 @@ static const struct bpf_func_proto bpf_get_socket_cookie_proto = { 
	.arg1_type      = ARG_PTR_TO_CTX,

};



BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb)

{

	struct sock *sk = sk_to_full_sk(skb->sk);

	kuid_t kuid;



	if (!sk || !sk_fullsock(sk))

		return overflowuid;

	kuid = sock_net_uid(sock_net(sk), sk);

	return from_kuid_munged(sock_net(sk)->user_ns, kuid);

}



static const struct bpf_func_proto bpf_get_socket_uid_proto = {

	.func           = bpf_get_socket_uid,

	.gpl_only       = false,

	.ret_type       = RET_INTEGER,

	.arg1_type      = ARG_PTR_TO_CTX,

};



static const struct bpf_func_proto *

bpf_base_func_proto(enum bpf_func_id func_id)

{
@@ -2655,6 +2673,8 @@ sk_filter_func_proto(enum bpf_func_id func_id) 
		return &bpf_skb_load_bytes_proto;

	case BPF_FUNC_get_socket_cookie:

		return &bpf_get_socket_cookie_proto;

	case BPF_FUNC_get_socket_uid:

		return &bpf_get_socket_uid_proto;

	default:

		return bpf_base_func_proto(func_id);

	}
@@ -2716,6 +2736,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) 
		return &bpf_skb_under_cgroup_proto;

	case BPF_FUNC_get_socket_cookie:

		return &bpf_get_socket_cookie_proto;

	case BPF_FUNC_get_socket_uid:

		return &bpf_get_socket_uid_proto;

	default:

		return bpf_base_func_proto(func_id);

	}

tools/include/uapi/linux/bpf.h

+2 −1
Original line number Diff line number Diff line
@@ -507,7 +507,8 @@ union bpf_attr { 
	FN(skb_change_head),		\

	FN(xdp_adjust_head),		\

	FN(probe_read_str),		\

	FN(get_socket_cookie),

	FN(get_socket_cookie),		\

	FN(get_socket_uid),



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

 * function eBPF program intends to call