36 lines
795 B
C
36 lines
795 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <inttypes.h>
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#include <linux/bpf.h>
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#include <bpf/bpf_endian.h>
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#include <bpf/bpf_helpers.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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/* This function extracts the last byte of the daddr, and uses it
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* as output dev index.
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*/
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SEC("lwt_xmit")
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int test_lwt_reroute(struct __sk_buff *skb)
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{
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struct iphdr *iph = NULL;
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void *start = (void *)(long)skb->data;
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void *end = (void *)(long)skb->data_end;
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/* set mark at most once */
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if (skb->mark != 0)
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return BPF_OK;
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if (start + sizeof(*iph) > end)
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return BPF_DROP;
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iph = (struct iphdr *)start;
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skb->mark = bpf_ntohl(iph->daddr) & 0xff;
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/* do not reroute x.x.x.0 packets */
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if (skb->mark == 0)
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return BPF_OK;
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return BPF_LWT_REROUTE;
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}
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char _license[] SEC("license") = "GPL";
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