// SPDX-License-Identifier: GPL-2.0 /* * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #include <linux/bpf.h> #include <linux/if_ether.h> #include <bpf/bpf_helpers.h> int _version SEC("version") = 1; SEC("xdp.frags") int xdp_adjust_frags(struct xdp_md *xdp) { __u8 *data_end = (void *)(long)xdp->data_end; __u8 *data = (void *)(long)xdp->data; __u8 val[16] = {}; __u32 offset; int err; if (data + sizeof(__u32) > data_end) return XDP_DROP; offset = *(__u32 *)data; err = bpf_xdp_load_bytes(xdp, offset, val, sizeof(val)); if (err < 0) return XDP_DROP; if (val[0] != 0xaa || val[15] != 0xaa) /* marker */ return XDP_DROP; val[0] = 0xbb; /* update the marker */ val[15] = 0xbb; err = bpf_xdp_store_bytes(xdp, offset, val, sizeof(val)); if (err < 0) return XDP_DROP; return XDP_PASS; } char _license[] SEC("license") = "GPL";