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Commit b1d9fc41 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: add napi_id read access to __sk_buff 

Add napi_id access to __sk_buff for socket filter program types, tc
program types and other bpf_convert_ctx_access() users. Having access
to skb->napi_id is useful for per RX queue listener siloing, f.e.
in combination with SO_ATTACH_REUSEPORT_EBPF and when busy polling is
used, meaning SO_REUSEPORT enabled listeners can then select the
corresponding socket at SYN time already [1]. The skb is marked via
skb_mark_napi_id() early in the receive path (e.g., napi_gro_receive()).

Currently, sockets can only use SO_INCOMING_NAPI_ID from 6d433902
("net: Introduce SO_INCOMING_NAPI_ID") as a socket option to look up
the NAPI ID associated with the queue for steering, which requires a
prior sk_mark_napi_id() after the socket was looked up.

Semantics for the __sk_buff napi_id access are similar, meaning if
skb->napi_id is < MIN_NAPI_ID (e.g. outgoing packets using sender_cpu),
then an invalid napi_id of 0 is returned to the program, otherwise a
valid non-zero napi_id.

  [1] http://netdevconf.org/2.1/slides/apr6/dumazet-BUSY-POLLING-Netdev-2.1.pdf



Suggested-by: default avatarEric Dumazet <edumazet@google.com>
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 73e64fa4

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -603,6 +603,7 @@ struct __sk_buff { 
	__u32 tc_classid;

	__u32 data;

	__u32 data_end;

	__u32 napi_id;

};



struct bpf_tunnel_key {

net/core/filter.c

+14 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
#include <net/dst_metadata.h>

#include <net/dst.h>

#include <net/sock_reuseport.h>

#include <net/busy_poll.h>



/**

 *	sk_filter_trim_cap - run a packet through a socket filter
@@ -3201,6 +3202,19 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
			*insn++ = BPF_MOV64_REG(si->dst_reg, si->dst_reg);

		else

			*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);

#endif

		break;



	case offsetof(struct __sk_buff, napi_id):

#if defined(CONFIG_NET_RX_BUSY_POLL)

		BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, napi_id) != 4);



		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, napi_id));

		*insn++ = BPF_JMP_IMM(BPF_JGE, si->dst_reg, MIN_NAPI_ID, 1);

		*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);

#else

		*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);

#endif

		break;

	}

tools/include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -603,6 +603,7 @@ struct __sk_buff { 
	__u32 tc_classid;

	__u32 data;

	__u32 data_end;

	__u32 napi_id;

};



struct bpf_tunnel_key {

tools/testing/selftests/bpf/test_verifier.c

+3 −0
Original line number Diff line number Diff line
@@ -772,6 +772,9 @@ static struct bpf_test tests[] = { 
			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, vlan_tci)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, napi_id)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),

			BPF_EXIT_INSN(),

		},

		.result = ACCEPT,