Commit 64b59025 authored by David Ahern's avatar David Ahern Committed by Alexei Starovoitov
Browse files

xdp: Add xdp_txq_info to xdp_buff 



Add xdp_txq_info as the Tx counterpart to xdp_rxq_info. At the
moment only the device is added. Other fields (queue_index)
can be added as use cases arise.

>From a UAPI perspective, add egress_ifindex to xdp context for
bpf programs to see the Tx device.

Update the verifier to only allow accesses to egress_ifindex by
XDP programs with BPF_XDP_DEVMAP expected attach type.

Signed-off-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200529220716.75383-4-dsahern@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent fbee97fe

include/net/xdp.h

+5 −0
Original line number Diff line number Diff line
@@ -61,12 +61,17 @@ struct xdp_rxq_info { 
	struct xdp_mem_info mem;

} ____cacheline_aligned; /* perf critical, avoid false-sharing */



struct xdp_txq_info {

	struct net_device *dev;

};



struct xdp_buff {

	void *data;

	void *data_end;

	void *data_meta;

	void *data_hard_start;

	struct xdp_rxq_info *rxq;

	struct xdp_txq_info *txq;

	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/

};

include/uapi/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -3707,6 +3707,8 @@ struct xdp_md { 
	/* Below access go through struct xdp_rxq_info */

	__u32 ingress_ifindex; /* rxq->dev->ifindex */

	__u32 rx_queue_index;  /* rxq->queue_index  */



	__u32 egress_ifindex;  /* txq->dev->ifindex */

};



enum sk_action {

kernel/bpf/devmap.c

+3 −0
Original line number Diff line number Diff line
@@ -476,8 +476,11 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev, 
					 struct xdp_buff *xdp,

					 struct bpf_prog *xdp_prog)

{

	struct xdp_txq_info txq = { .dev = dev };

	u32 act;



	xdp->txq = &txq;



	act = bpf_prog_run_xdp(xdp_prog, xdp);

	switch (act) {

	case XDP_PASS:

net/core/filter.c

+17 −0
Original line number Diff line number Diff line
@@ -7015,6 +7015,13 @@ static bool xdp_is_valid_access(int off, int size, 
				const struct bpf_prog *prog,

				struct bpf_insn_access_aux *info)

{

	if (prog->expected_attach_type != BPF_XDP_DEVMAP) {

		switch (off) {

		case offsetof(struct xdp_md, egress_ifindex):

			return false;

		}

	}



	if (type == BPF_WRITE) {

		if (bpf_prog_is_dev_bound(prog->aux)) {

			switch (off) {
@@ -7985,6 +7992,16 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, 
				      offsetof(struct xdp_rxq_info,

					       queue_index));

		break;

	case offsetof(struct xdp_md, egress_ifindex):

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, txq),

				      si->dst_reg, si->src_reg,

				      offsetof(struct xdp_buff, txq));

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_txq_info, dev),

				      si->dst_reg, si->dst_reg,

				      offsetof(struct xdp_txq_info, dev));

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

				      offsetof(struct net_device, ifindex));

		break;

	}



	return insn - insn_buf;

tools/include/uapi/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -3706,6 +3706,8 @@ struct xdp_md { 
	/* Below access go through struct xdp_rxq_info */

	__u32 ingress_ifindex; /* rxq->dev->ifindex */

	__u32 rx_queue_index;  /* rxq->queue_index  */



	__u32 egress_ifindex;  /* txq->dev->ifindex */

};



enum sk_action {

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