netdev - [PATCH v5 bpf-next 6/8] bpf: devmap: check XDP features in __xdp

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Date:   Wed,  1 Feb 2023 11:24:22 +0100
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, edumazet@...gle.com, hawk@...nel.org,
        toke@...hat.com, memxor@...il.com, alardam@...il.com,
        saeedm@...dia.com, anthony.l.nguyen@...el.com, gospo@...adcom.com,
        vladimir.oltean@....com, nbd@....name, john@...ozen.org,
        leon@...nel.org, simon.horman@...igine.com, aelior@...vell.com,
        christophe.jaillet@...adoo.fr, ecree.xilinx@...il.com,
        mst@...hat.com, bjorn@...nel.org, magnus.karlsson@...el.com,
        maciej.fijalkowski@...el.com, intel-wired-lan@...ts.osuosl.org,
        lorenzo.bianconi@...hat.com, martin.lau@...ux.dev, sdf@...gle.com,
        gerhard@...leder-embedded.com
Subject: [PATCH v5 bpf-next 6/8] bpf: devmap: check XDP features in __xdp_enqueue routine

Check if the destination device implements ndo_xdp_xmit callback relying
on NETDEV_XDP_ACT_NDO_XMIT flags. Moreover, check if the destination device
supports XDP non-linear frame in __xdp_enqueue and is_valid_dst routines.
This patch allows to perform XDP_REDIRECT on non-linear XDP buffers.

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
Co-developed-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 kernel/bpf/devmap.c | 16 +++++++++++++---
 net/core/filter.c   | 13 +++++--------
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index d01e4c55b376..2675fefc6cb6 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -474,7 +474,11 @@ static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 {
 	int err;
 
-	if (!dev->netdev_ops->ndo_xdp_xmit)
+	if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
+		return -EOPNOTSUPP;
+
+	if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
+		     xdp_frame_has_frags(xdpf)))
 		return -EOPNOTSUPP;
 
 	err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
@@ -532,8 +536,14 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 
 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
 {
-	if (!obj ||
-	    !obj->dev->netdev_ops->ndo_xdp_xmit)
+	if (!obj)
+		return false;
+
+	if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
+		return false;
+
+	if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
+		     xdp_frame_has_frags(xdpf)))
 		return false;
 
 	if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
diff --git a/net/core/filter.c b/net/core/filter.c
index 0039cf16713e..2ce06a72a5ba 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4318,16 +4318,13 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 	enum bpf_map_type map_type = ri->map_type;
 
-	/* XDP_REDIRECT is not fully supported yet for xdp frags since
-	 * not all XDP capable drivers can map non-linear xdp_frame in
-	 * ndo_xdp_xmit.
-	 */
-	if (unlikely(xdp_buff_has_frags(xdp) &&
-		     map_type != BPF_MAP_TYPE_CPUMAP))
-		return -EOPNOTSUPP;
+	if (map_type == BPF_MAP_TYPE_XSKMAP) {
+		/* XDP_REDIRECT is not supported AF_XDP yet. */
+		if (unlikely(xdp_buff_has_frags(xdp)))
+			return -EOPNOTSUPP;
 
-	if (map_type == BPF_MAP_TYPE_XSKMAP)
 		return __xdp_do_redirect_xsk(ri, dev, xdp, xdp_prog);
+	}
 
 	return __xdp_do_redirect_frame(ri, dev, xdp_convert_buff_to_frame(xdp),
 				       xdp_prog);
-- 
2.39.1