89 lines
2.5 KiB
C
89 lines
2.5 KiB
C
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/*
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* SPDX-License-Identifier: GPL-2.0 OR Apache-2.0
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* Dual-licensed under GPL version 2.0 or Apache License version 2.0
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* Copyright (c) 2020 Cisco and/or its affiliates.
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*/
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#include <linux/bpf.h>
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#include <linux/in.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/udp.h>
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#include <bpf/bpf_helpers.h>
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/*
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* when compiled, debug print can be viewed with eg.
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* sudo cat /sys/kernel/debug/tracing/trace_pipe
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*/
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#ifdef DEBUG
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#define s__(n) # n
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#define s_(n) s__(n)
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#define x_(fmt) __FILE__ ":" s_(__LINE__) ": " fmt "\n"
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#define DEBUG_PRINT_(fmt, ...) do { \
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const char fmt__[] = fmt; \
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bpf_trace_printk(fmt__, sizeof(fmt), ## __VA_ARGS__); } while(0)
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#define DEBUG_PRINT(fmt, ...) DEBUG_PRINT_ (x_(fmt), ## __VA_ARGS__)
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#else /* DEBUG */
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#define DEBUG_PRINT(fmt, ...)
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#endif /* DEBUG */
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#define ntohs(x) __constant_ntohs(x)
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SEC("maps")
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struct bpf_map_def xsks_map = {
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.type = BPF_MAP_TYPE_XSKMAP,
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.key_size = sizeof(int),
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.value_size = sizeof(int),
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.max_entries = 64, /* max 64 queues per device */
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};
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SEC("xdp_sock")
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int xdp_sock_prog(struct xdp_md *ctx) {
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const void *data = (void *)(long)ctx->data;
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const void *data_end = (void *)(long)ctx->data_end;
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DEBUG_PRINT("rx %ld bytes packet", (long)data_end - (long)data);
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/* smallest packet we are interesting in is ip-ip */
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if (data + sizeof(struct ethhdr) + 2 * sizeof(struct iphdr) > data_end) {
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DEBUG_PRINT("packet too small");
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return XDP_PASS;
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}
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const struct ethhdr *eth = data;
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if (eth->h_proto != ntohs(ETH_P_IP)) {
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DEBUG_PRINT("unsupported eth proto %x", (int)eth->h_proto);
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return XDP_PASS;
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}
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const struct iphdr *ip = (void *)(eth + 1);
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switch (ip->protocol) {
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case IPPROTO_UDP: {
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const struct udphdr *udp = (void *)(ip + 1);
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if (udp->dest != ntohs(4789)) { /* VxLAN dest port */
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DEBUG_PRINT("unsupported udp dst port %x", (int)udp->dest);
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return XDP_PASS;
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}
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}
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case IPPROTO_IPIP:
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case IPPROTO_ESP:
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break;
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default:
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DEBUG_PRINT("unsupported ip proto %x", (int)ip->protocol);
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return XDP_PASS;
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}
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int qid = ctx->rx_queue_index;
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if (!bpf_map_lookup_elem(&xsks_map, &qid))
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{
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DEBUG_PRINT("no socket found");
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return XDP_PASS;
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}
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DEBUG_PRINT("going to socket %d", qid);
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return bpf_redirect_map(&xsks_map, qid, 0);
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}
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/* actually Dual GPLv2/Apache2, but GPLv2 as far as kernel is concerned */
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SEC("license")
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char _license[] = "GPL";
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