mirror of
https://github.com/xdp-project/bpf-examples.git
synced 2024-05-06 15:54:53 +00:00
cecd6b54f2
Add a per-flow rate limit, limiting how often new timestamp entries can be created. As part of this, add per-flow state keeping track of when last timestamp was created and last seen identifier for each flow. Additionally, remove timestamp entry as soon as RTT is calculated, as last seen identifier is used to find first unique value instead. Furthermore, remove packet_timestamp struct and only use __u64 as timestamp, as used memeber is no longer needed. This initial commit lacks cleanup of flow-state, user-configuration of rate limit, mechanism to handle bursts etc. Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include "pping.h"
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#include "pping_helpers.h"
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char _license[] SEC("license") = "GPL";
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(key_size, sizeof(struct packet_id));
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__uint(value_size, sizeof(__u64));
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__uint(max_entries, 16384);
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__uint(pinning, LIBBPF_PIN_BY_NAME);
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} ts_start SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__uint(key_size, sizeof(__u32));
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__uint(value_size, sizeof(__u32));
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} rtt_events SEC(".maps");
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// XDP program for parsing identifier in ingress traffic and check for match in map
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SEC(XDP_PROG_SEC)
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int xdp_prog_ingress(struct xdp_md *ctx)
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{
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struct packet_id p_id = { 0 };
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__u64 *p_ts;
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struct rtt_event event = { 0 };
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struct parsing_context pctx = {
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.data = (void *)(long)ctx->data,
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.data_end = (void *)(long)ctx->data_end,
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.pkt_len = pctx.data_end - pctx.data,
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.nh = { .pos = pctx.data },
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};
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if (parse_packet_identifier(&pctx, false, &p_id) < 0)
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goto end;
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p_ts = bpf_map_lookup_elem(&ts_start, &p_id);
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if (!p_ts)
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goto end;
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event.rtt = bpf_ktime_get_ns() - *p_ts;
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/*
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* Attempt to delete timestamp entry as soon as RTT is calculated.
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* But could have potential concurrency issue where multiple packets
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* manage to match against the identifier before it can be deleted.
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*/
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bpf_map_delete_elem(&ts_start, &p_id);
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__builtin_memcpy(&event.flow, &p_id.flow, sizeof(struct network_tuple));
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bpf_perf_event_output(ctx, &rtt_events, BPF_F_CURRENT_CPU, &event,
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sizeof(event));
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end:
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return XDP_PASS;
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}
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