54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/pkt_cls.h>
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#include <bpf/bpf_helpers.h>
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#define __round_mask(x, y) ((__typeof__(x))((y) - 1))
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#define round_up(x, y) ((((x) - 1) | __round_mask(x, y)) + 1)
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#define ctx_ptr(ctx, mem) (void *)(unsigned long)ctx->mem
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SEC("t")
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int ing_cls(struct __sk_buff *ctx)
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{
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__u8 *data, *data_meta, *data_end;
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__u32 diff = 0;
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data_meta = ctx_ptr(ctx, data_meta);
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data_end = ctx_ptr(ctx, data_end);
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data = ctx_ptr(ctx, data);
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if (data + ETH_ALEN > data_end ||
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data_meta + round_up(ETH_ALEN, 4) > data)
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return TC_ACT_SHOT;
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diff |= ((__u32 *)data_meta)[0] ^ ((__u32 *)data)[0];
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diff |= ((__u16 *)data_meta)[2] ^ ((__u16 *)data)[2];
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return diff ? TC_ACT_SHOT : TC_ACT_OK;
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}
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SEC("x")
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int ing_xdp(struct xdp_md *ctx)
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{
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__u8 *data, *data_meta, *data_end;
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int ret;
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ret = bpf_xdp_adjust_meta(ctx, -round_up(ETH_ALEN, 4));
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if (ret < 0)
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return XDP_DROP;
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data_meta = ctx_ptr(ctx, data_meta);
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data_end = ctx_ptr(ctx, data_end);
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data = ctx_ptr(ctx, data);
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if (data + ETH_ALEN > data_end ||
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data_meta + round_up(ETH_ALEN, 4) > data)
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return XDP_DROP;
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__builtin_memcpy(data_meta, data, ETH_ALEN);
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";
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