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Commit ded092cd authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: add bpf_set_hash helper for tc progs 



Allow for tc BPF programs to set a skb->hash, apart from clearing
and triggering a recalc that we have right now. It allows for BPF
to implement a custom hashing routine for skb_get_hash().

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 966789fb

include/uapi/linux/bpf.h

+7 −1
Original line number Diff line number Diff line
@@ -513,6 +513,11 @@ union bpf_attr { 
 *     Get the owner uid of the socket stored inside sk_buff.

 *     @skb: pointer to skb

 *     Return: uid of the socket owner on success or overflowuid if failed.

 *

 * u32 bpf_set_hash(skb, hash)

 *     Set full skb->hash.

 *     @skb: pointer to skb

 *     @hash: hash to set

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -562,7 +567,8 @@ union bpf_attr { 
	FN(xdp_adjust_head),		\

	FN(probe_read_str),		\

	FN(get_socket_cookie),		\

	FN(get_socket_uid),

	FN(get_socket_uid),		\

	FN(set_hash),



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

 * function eBPF program intends to call

net/core/filter.c

+20 −0
Original line number Diff line number Diff line
@@ -1874,6 +1874,24 @@ static const struct bpf_func_proto bpf_set_hash_invalid_proto = { 
	.arg1_type	= ARG_PTR_TO_CTX,

};



BPF_CALL_2(bpf_set_hash, struct sk_buff *, skb, u32, hash)

{

	/* Set user specified hash as L4(+), so that it gets returned

	 * on skb_get_hash() call unless BPF prog later on triggers a

	 * skb_clear_hash().

	 */

	__skb_set_sw_hash(skb, hash, true);

	return 0;

}



static const struct bpf_func_proto bpf_set_hash_proto = {

	.func		= bpf_set_hash,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

};



BPF_CALL_3(bpf_skb_vlan_push, struct sk_buff *, skb, __be16, vlan_proto,

	   u16, vlan_tci)

{
@@ -2744,6 +2762,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) 
		return &bpf_get_hash_recalc_proto;

	case BPF_FUNC_set_hash_invalid:

		return &bpf_set_hash_invalid_proto;

	case BPF_FUNC_set_hash:

		return &bpf_set_hash_proto;

	case BPF_FUNC_perf_event_output:

		return &bpf_skb_event_output_proto;

	case BPF_FUNC_get_smp_processor_id:

tools/include/uapi/linux/bpf.h

+7 −1
Original line number Diff line number Diff line
@@ -513,6 +513,11 @@ union bpf_attr { 
 *     Get the owner uid of the socket stored inside sk_buff.

 *     @skb: pointer to skb

 *     Return: uid of the socket owner on success or overflowuid if failed.

 *

 * u32 bpf_set_hash(skb, hash)

 *     Set full skb->hash.

 *     @skb: pointer to skb

 *     @hash: hash to set

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -562,7 +567,8 @@ union bpf_attr { 
	FN(xdp_adjust_head),		\

	FN(probe_read_str),		\

	FN(get_socket_cookie),		\

	FN(get_socket_uid),

	FN(get_socket_uid),		\

	FN(set_hash),



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

 * function eBPF program intends to call