90 lines
2.7 KiB
Diff
90 lines
2.7 KiB
Diff
From 405caa1424358032574230ec5479e64834869298 Mon Sep 17 00:00:00 2001
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From: Alfredo Cardigliano <cardigliano@ntop.org>
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Date: Thu, 13 Apr 2023 13:03:28 +0200
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Subject: [PATCH] Implement probabilistic sampling
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---
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kernel/linux/pf_ring.h | 4 +++-
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kernel/pf_ring.c | 34 ++++++++++++++++++++++++----------
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2 files changed, 27 insertions(+), 11 deletions(-)
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--- a/kernel/linux/pf_ring.h
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+++ b/kernel/linux/pf_ring.h
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@@ -1310,7 +1310,9 @@ struct pf_ring_socket {
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u_char *ring_slots; /* Points to ring_memory+sizeof(FlowSlotInfo) */
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/* Packet Sampling */
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- u_int32_t pktToSample, sample_rate;
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+ u_int32_t sample_rate;
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+ u_int32_t pkts_to_sample;
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+ u_int32_t sample_rnd_shift;
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/* Virtual Filtering Device */
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virtual_filtering_device_element *v_filtering_dev;
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--- a/kernel/pf_ring.c
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+++ b/kernel/pf_ring.c
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@@ -3695,6 +3695,26 @@ int bpf_filter_skb(struct sk_buff *skb,
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/* ********************************** */
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+int sample_packet(struct pf_ring_socket *pfr) {
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+ if(pfr->pkts_to_sample <= 1) {
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+ u_int32_t rnd = 0;
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+
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+ get_random_bytes(&rnd, sizeof(u_int32_t));
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+ rnd = rnd % pfr->sample_rate;
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+
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+ pfr->pkts_to_sample = pfr->sample_rate - pfr->sample_rnd_shift + rnd;
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+
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+ pfr->sample_rnd_shift = rnd;
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+
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+ return 1; /* Pass packet */
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+ } else {
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+ pfr->pkts_to_sample--;
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+ return 0; /* Discard packet */
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+ }
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+}
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+
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+/* ********************************** */
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+
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u_int32_t default_rehash_rss_func(struct sk_buff *skb, struct pfring_pkthdr *hdr)
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{
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return hash_pkt_header(hdr, 0);
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@@ -3805,12 +3825,9 @@ static int add_skb_to_ring(struct sk_buf
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if(pfr->sample_rate > 1) {
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spin_lock_bh(&pfr->ring_index_lock);
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- if(pfr->pktToSample <= 1) {
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- pfr->pktToSample = pfr->sample_rate;
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- } else {
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+ if(!sample_packet(pfr)) {
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+ /* Discard packet */
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pfr->slots_info->tot_pkts++;
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- pfr->pktToSample--;
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-
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spin_unlock_bh(&pfr->ring_index_lock);
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atomic_dec(&pfr->num_ring_users);
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return(-1);
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@@ -4161,11 +4178,8 @@ int pf_ring_skb_ring_handler(struct sk_b
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if(pfr->sample_rate > 1) {
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spin_lock_bh(&pfr->ring_index_lock);
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- if(pfr->pktToSample <= 1) {
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- pfr->pktToSample = pfr->sample_rate;
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- } else {
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+ if (!sample_packet(pfr)) {
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pfr->slots_info->tot_pkts++;
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- pfr->pktToSample--;
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rc = 0;
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}
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spin_unlock_bh(&pfr->ring_index_lock);
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@@ -7957,7 +7971,7 @@ static int ring_getsockopt(struct socket
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if(copy_to_user(optval, lowest_if_mac, ETH_ALEN))
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return(-EFAULT);
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} else {
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- char *dev_addr = pfr->ring_dev->dev->dev_addr;
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+ const char *dev_addr = pfr->ring_dev->dev->dev_addr;
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if (dev_addr == NULL) /* e.g. 'any' device */
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dev_addr = empty_mac;
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