[PATCH v5 bpf-next 02/11] net: uapi for XDP programs in the egress path

[David Ahern <dsahern@kernel.org>]

From: David Ahern <dahern@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 <dahern@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)