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

Running programs in the egress path, on skbs or xdp_frames, does not
require driver specific resources like Rx path. Accordingly, the
programs can be run in core code, so add xdp_egress_prog to net_device
to hold a reference to an attached program.

For UAPI, add XDP_FLAGS_EGRESS_MODE to specify attach is at egress, add
a new attach flag, XDP_ATTACHED_EGRESS_CORE, for reporting the attach
point at the core, egress level and add IFLA_XDP_EGRESS_PROG_ID
for reporting the program id. Add rtnl_xdp_prog_egress to fill in
link message with egress data.

Signed-off-by: David Ahern <dah...@digitalocean.com>
---
 include/linux/netdevice.h          |  1 +
 include/uapi/linux/if_link.h       |  6 +++++-
 net/core/rtnetlink.c               | 23 +++++++++++++++++++++--
 tools/include/uapi/linux/if_link.h |  6 +++++-
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5a8d40f1ffe2..594c13d4cd00 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1995,6 +1995,7 @@ struct net_device {
        unsigned int            real_num_rx_queues;
 
        struct bpf_prog __rcu   *xdp_prog;
+       struct bpf_prog __rcu   *xdp_egress_prog;
        unsigned long           gro_flush_timeout;
        int                     napi_defer_hard_irqs;
        rx_handler_func_t __rcu *rx_handler;
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index a009365ad67b..de32a9e94d74 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -976,9 +976,11 @@ enum {
 #define XDP_FLAGS_DRV_MODE             (1U << 2)
 #define XDP_FLAGS_HW_MODE              (1U << 3)
 #define XDP_FLAGS_REPLACE              (1U << 4)
+#define XDP_FLAGS_EGRESS_MODE          (1U << 5)
 #define XDP_FLAGS_MODES                        (XDP_FLAGS_SKB_MODE | \
                                         XDP_FLAGS_DRV_MODE | \
-                                        XDP_FLAGS_HW_MODE)
+                                        XDP_FLAGS_HW_MODE | \
+                                        XDP_FLAGS_EGRESS_MODE)
 #define XDP_FLAGS_MASK                 (XDP_FLAGS_UPDATE_IF_NOEXIST | \
                                         XDP_FLAGS_MODES | XDP_FLAGS_REPLACE)
 
@@ -989,6 +991,7 @@ enum {
        XDP_ATTACHED_SKB,
        XDP_ATTACHED_HW,
        XDP_ATTACHED_MULTI,
+       XDP_ATTACHED_EGRESS_CORE,
 };
 
 enum {
@@ -1001,6 +1004,7 @@ enum {
        IFLA_XDP_SKB_PROG_ID,
        IFLA_XDP_HW_PROG_ID,
        IFLA_XDP_EXPECTED_FD,
+       IFLA_XDP_EGRESS_PROG_ID,
        __IFLA_XDP_MAX,
 };
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2269199c5891..9084dfebc699 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -982,7 +982,7 @@ static size_t rtnl_xdp_size(void)
        size_t xdp_size = nla_total_size(0) +   /* nest IFLA_XDP */
                          nla_total_size(1) +   /* XDP_ATTACHED */
                          nla_total_size(4) +   /* XDP_PROG_ID (or 1st mode) */
-                         nla_total_size(4);    /* XDP_<mode>_PROG_ID */
+                         nla_total_size(4) * 2; /* XDP_<mode>_PROG_ID */
 
        return xdp_size;
 }
@@ -1402,6 +1402,18 @@ static int rtnl_fill_link_ifmap(struct sk_buff *skb, 
struct net_device *dev)
        return 0;
 }
 
+static u32 rtnl_xdp_prog_egress(struct net_device *dev)
+{
+       const struct bpf_prog *prog;
+
+       ASSERT_RTNL();
+
+       prog = rtnl_dereference(dev->xdp_egress_prog);
+       if (!prog)
+               return 0;
+       return prog->aux->id;
+}
+
 static u32 rtnl_xdp_prog_skb(struct net_device *dev)
 {
        const struct bpf_prog *generic_xdp_prog;
@@ -1474,6 +1486,12 @@ static int rtnl_xdp_fill(struct sk_buff *skb, struct 
net_device *dev)
                                  IFLA_XDP_HW_PROG_ID, rtnl_xdp_prog_hw);
        if (err)
                goto err_cancel;
+       err = rtnl_xdp_report_one(skb, dev, &prog_id, &mode,
+                                 XDP_ATTACHED_EGRESS_CORE,
+                                 IFLA_XDP_EGRESS_PROG_ID,
+                                 rtnl_xdp_prog_egress);
+       if (err)
+               goto err_cancel;
 
        err = nla_put_u8(skb, IFLA_XDP_ATTACHED, mode);
        if (err)
@@ -2790,7 +2808,8 @@ static int do_setlink(const struct sk_buff *skb,
                if (err < 0)
                        goto errout;
 
-               if (xdp[IFLA_XDP_ATTACHED] || xdp[IFLA_XDP_PROG_ID]) {
+               if (xdp[IFLA_XDP_ATTACHED] || xdp[IFLA_XDP_PROG_ID] ||
+                   xdp[IFLA_XDP_EGRESS_PROG_ID]) {
                        err = -EINVAL;
                        goto errout;
                }
diff --git a/tools/include/uapi/linux/if_link.h 
b/tools/include/uapi/linux/if_link.h
index cafedbbfefbe..1d61cb46a77c 100644
--- a/tools/include/uapi/linux/if_link.h
+++ b/tools/include/uapi/linux/if_link.h
@@ -964,9 +964,11 @@ enum {
 #define XDP_FLAGS_DRV_MODE             (1U << 2)
 #define XDP_FLAGS_HW_MODE              (1U << 3)
 #define XDP_FLAGS_REPLACE              (1U << 4)
+#define XDP_FLAGS_EGRESS_MODE          (1U << 5)
 #define XDP_FLAGS_MODES                        (XDP_FLAGS_SKB_MODE | \
                                         XDP_FLAGS_DRV_MODE | \
-                                        XDP_FLAGS_HW_MODE)
+                                        XDP_FLAGS_HW_MODE | \
+                                        XDP_FLAGS_EGRESS_MODE)
 #define XDP_FLAGS_MASK                 (XDP_FLAGS_UPDATE_IF_NOEXIST | \
                                         XDP_FLAGS_MODES | XDP_FLAGS_REPLACE)
 
@@ -977,6 +979,7 @@ enum {
        XDP_ATTACHED_SKB,
        XDP_ATTACHED_HW,
        XDP_ATTACHED_MULTI,
+       XDP_ATTACHED_EGRESS_CORE,
 };
 
 enum {
@@ -989,6 +992,7 @@ enum {
        IFLA_XDP_SKB_PROG_ID,
        IFLA_XDP_HW_PROG_ID,
        IFLA_XDP_EXPECTED_FD,
+       IFLA_XDP_EGRESS_PROG_ID,
        __IFLA_XDP_MAX,
 };
 
-- 
2.21.1 (Apple Git-122.3)

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