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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | /* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io * * 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. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #define KBUILD_MODNAME "foo" #include <uapi/linux/bpf.h> #include <linux/in.h> #include <linux/if_ether.h> #include <linux/if_packet.h> #include <linux/if_vlan.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <bpf/bpf_helpers.h> /* The 2nd xdp prog on egress does not support skb mode, so we define two * maps, tx_port_general and tx_port_native. */ struct { __uint(type, BPF_MAP_TYPE_DEVMAP); __uint(key_size, sizeof(int)); __uint(value_size, sizeof(int)); __uint(max_entries, 100); } tx_port_general SEC(".maps"); struct { __uint(type, BPF_MAP_TYPE_DEVMAP); __uint(key_size, sizeof(int)); __uint(value_size, sizeof(struct bpf_devmap_val)); __uint(max_entries, 100); } tx_port_native SEC(".maps"); /* Count RX packets, as XDP bpf_prog doesn't get direct TX-success * feedback. Redirect TX errors can be caught via a tracepoint. */ struct { __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); __type(key, u32); __type(value, long); __uint(max_entries, 1); } rxcnt SEC(".maps"); /* map to store egress interface mac address */ struct { __uint(type, BPF_MAP_TYPE_ARRAY); __type(key, u32); __type(value, __be64); __uint(max_entries, 1); } tx_mac SEC(".maps"); static void swap_src_dst_mac(void *data) { unsigned short *p = data; unsigned short dst[3]; dst[0] = p[0]; dst[1] = p[1]; dst[2] = p[2]; p[0] = p[3]; p[1] = p[4]; p[2] = p[5]; p[3] = dst[0]; p[4] = dst[1]; p[5] = dst[2]; } static __always_inline int xdp_redirect_map(struct xdp_md *ctx, void *redirect_map) { void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; struct ethhdr *eth = data; int rc = XDP_DROP; long *value; u32 key = 0; u64 nh_off; int vport; nh_off = sizeof(*eth); if (data + nh_off > data_end) return rc; /* constant virtual port */ vport = 0; /* count packet in global counter */ value = bpf_map_lookup_elem(&rxcnt, &key); if (value) *value += 1; swap_src_dst_mac(data); /* send packet out physical port */ return bpf_redirect_map(redirect_map, vport, 0); } SEC("xdp_redirect_general") int xdp_redirect_map_general(struct xdp_md *ctx) { return xdp_redirect_map(ctx, &tx_port_general); } SEC("xdp_redirect_native") int xdp_redirect_map_native(struct xdp_md *ctx) { return xdp_redirect_map(ctx, &tx_port_native); } SEC("xdp_devmap/map_prog") int xdp_redirect_map_egress(struct xdp_md *ctx) { void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; struct ethhdr *eth = data; __be64 *mac; u32 key = 0; u64 nh_off; nh_off = sizeof(*eth); if (data + nh_off > data_end) return XDP_DROP; mac = bpf_map_lookup_elem(&tx_mac, &key); if (mac) __builtin_memcpy(eth->h_source, mac, ETH_ALEN); return XDP_PASS; } /* Redirect require an XDP bpf_prog loaded on the TX device */ SEC("xdp_redirect_dummy") int xdp_redirect_dummy_prog(struct xdp_md *ctx) { return XDP_PASS; } char _license[] SEC("license") = "GPL"; |