libxdp: add device binding support

Kernel 6.3 supported for some NIC offloads for XDP programs.
The feature in XDP is known to be XDP hints. XDP hints are only
supported if the XDP program is bound to the NIC device using the
BPF_F_XDP_DEV_BOUND_ONLY binding flag.

The device binding flag is represented through `XDP_ATTACH_DEVBIND',
a new attach flag for `xdp_program__attach`. Device binding is
propagated to the dispatcher. Any subsequent programs attachments
are rejected if they are different from the already running dispatcher
on a network interface.

The flag is recored using a new variable in `struct xdp_dispatcher_config`.

Signed-off-by: Jalal Mostafa <[email protected]>

Author: jalalmostafa

.gitignore

@@ -66,3 +66,5 @@ compile_commands.json
 
 # BPF skeleton files
 *.skel.h
+
+.vscode

headers/xdp/libxdp.h

@@ -23,6 +23,9 @@ extern "C" {
 #define XDP_BPFFS_MOUNT_ENVVAR "LIBXDP_BPFFS_AUTOMOUNT"
 #define XDP_OBJECT_ENVVAR "LIBXDP_OBJECT_PATH"
 
+#define XDP_ATTACH_DEVBIND (1 << 0)
+#define XDP_ATTACH_FLAGS (XDP_ATTACH_DEVBIND)
+
 enum xdp_attach_mode {
 	XDP_MODE_UNSPEC = 0,
 	XDP_MODE_NATIVE,
@@ -116,6 +119,7 @@ struct xdp_program *xdp_multiprog__hw_prog(const struct xdp_multiprog *mp);
 bool xdp_multiprog__is_legacy(const struct xdp_multiprog *mp);
 int xdp_multiprog__program_count(const struct xdp_multiprog *mp);
 bool xdp_multiprog__xdp_frags_support(const struct xdp_multiprog *mp);
+bool xdp_multiprog__xdp_dev_bound(const struct xdp_multiprog *mp);
 
 /* Only following members can be set at once:
  *

headers/xdp/prog_dispatcher.h

@@ -6,7 +6,7 @@
 #include <linux/types.h>
 
 #define XDP_METADATA_SECTION "xdp_metadata"
-#define XDP_DISPATCHER_VERSION 2
+#define XDP_DISPATCHER_VERSION 3
 
 /* magic byte is 'X' + 'D' + 'P' (88+68+80=236) */
 #define XDP_DISPATCHER_MAGIC 236
@@ -29,6 +29,7 @@ struct xdp_dispatcher_config {
 	__u32 chain_call_actions[MAX_DISPATCHER_ACTIONS];
 	__u32 run_prios[MAX_DISPATCHER_ACTIONS];
 	__u32 program_flags[MAX_DISPATCHER_ACTIONS];
+	__u8 is_xdp_devbound;              /* Whether this dispatcher is bounded to a device */
 };
 
 #endif