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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: David Ahern <dsahern@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200529220716.75383-4-dsahern@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
David Ahern 2020-05-29 16:07:14 -06:00 committed by Alexei Starovoitov
parent fbee97feed
commit 64b59025c1
5 changed files with 29 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/net/xdp.h
View File

@ -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*/
};

2
include/uapi/linux/bpf.h
View File

@ -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 {

3
kernel/bpf/devmap.c
View File

@ -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:

17
net/core/filter.c
View File

@ -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;

2
tools/include/uapi/linux/bpf.h
View File

@ -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 {