43 lines
1000 B
C
43 lines
1000 B
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <bpf/bpf_helpers.h>
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int _version SEC("version") = 1;
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SEC("xdp.frags")
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int xdp_adjust_frags(struct xdp_md *xdp)
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{
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__u8 *data_end = (void *)(long)xdp->data_end;
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__u8 *data = (void *)(long)xdp->data;
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__u8 val[16] = {};
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__u32 offset;
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int err;
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if (data + sizeof(__u32) > data_end)
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return XDP_DROP;
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offset = *(__u32 *)data;
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err = bpf_xdp_load_bytes(xdp, offset, val, sizeof(val));
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if (err < 0)
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return XDP_DROP;
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if (val[0] != 0xaa || val[15] != 0xaa) /* marker */
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return XDP_DROP;
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val[0] = 0xbb; /* update the marker */
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val[15] = 0xbb;
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err = bpf_xdp_store_bytes(xdp, offset, val, sizeof(val));
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if (err < 0)
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return XDP_DROP;
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";
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