[PATCH v5 bpf-next 05/11] xdp: Add xdp_txq_info to xdp_buff

[David Ahern]

From: David Ahern <dah...@digitalocean.com>

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.

Update the verifier to reject accesses to egress_ifindex by
rx programs.

Signed-off-by: David Ahern <dah...@digitalocean.com>
---
 include/net/xdp.h              |  5 +++++
 include/uapi/linux/bpf.h       |  2 ++
 net/core/filter.c              | 15 +++++++++++++++
 tools/include/uapi/linux/bpf.h |  2 ++
 4 files changed, 24 insertions(+)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 3264fa882de3..2b85b8649201 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -63,6 +63,10 @@ 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;
@@ -70,6 +74,7 @@ struct xdp_buff {
        void *data_hard_start;
        unsigned long handle;
        struct xdp_rxq_info *rxq;
+       struct xdp_txq_info *txq;
 };
 
 struct xdp_frame {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 05accb95bb4a..54d50dd62498 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3586,6 +3586,8 @@ 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 {
diff --git a/net/core/filter.c b/net/core/filter.c
index 19272eb7bb8f..c1edd800b4f1 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6940,6 +6940,11 @@ static bool xdp_is_valid_access(int off, int size,
                case offsetof(struct xdp_md, rx_queue_index):
                        return false;
                }
+       } else if (prog->expected_attach_type != BPF_XDP_EGRESS) {
+               switch (off) {
+               case offsetof(struct xdp_md, egress_ifindex):
+                       return false;
+               }
        }
 
        if (type == BPF_WRITE) {
@@ -7889,6 +7894,16 @@ 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;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 05accb95bb4a..54d50dd62498 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3586,6 +3586,8 @@ 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 {
-- 
2.21.1 (Apple Git-122.3)