From 05e59e5fb0064c97a1c10921ecd549f2d4a58565 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:14:40 +0000
Subject: [PATCH] add REDIRECT
---
kernel/samples/bpf/xdp_adjust_tail_kern.c | 21 ++++++++++++---------
1 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/kernel/samples/bpf/xdp_adjust_tail_kern.c b/kernel/samples/bpf/xdp_adjust_tail_kern.c
index 411fdb2..ffdd548 100644
--- a/kernel/samples/bpf/xdp_adjust_tail_kern.c
+++ b/kernel/samples/bpf/xdp_adjust_tail_kern.c
@@ -18,19 +18,22 @@
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/icmp.h>
-#include "bpf_helpers.h"
+#include <bpf/bpf_helpers.h>
#define DEFAULT_TTL 64
#define MAX_PCKT_SIZE 600
#define ICMP_TOOBIG_SIZE 98
#define ICMP_TOOBIG_PAYLOAD_SIZE 92
-struct bpf_map_def SEC("maps") icmpcnt = {
- .type = BPF_MAP_TYPE_ARRAY,
- .key_size = sizeof(__u32),
- .value_size = sizeof(__u64),
- .max_entries = 1,
-};
+/* volatile to prevent compiler optimizations */
+static volatile __u32 max_pcktsz = MAX_PCKT_SIZE;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, __u32);
+ __type(value, __u64);
+ __uint(max_entries, 1);
+} icmpcnt SEC(".maps");
static __always_inline void count_icmp(void)
{
@@ -92,7 +95,7 @@
orig_iph = data + off;
icmp_hdr->type = ICMP_DEST_UNREACH;
icmp_hdr->code = ICMP_FRAG_NEEDED;
- icmp_hdr->un.frag.mtu = htons(MAX_PCKT_SIZE-sizeof(struct ethhdr));
+ icmp_hdr->un.frag.mtu = htons(max_pcktsz - sizeof(struct ethhdr));
icmp_hdr->checksum = 0;
ipv4_csum(icmp_hdr, ICMP_TOOBIG_PAYLOAD_SIZE, &csum);
icmp_hdr->checksum = csum;
@@ -121,7 +124,7 @@
int pckt_size = data_end - data;
int offset;
- if (pckt_size > MAX_PCKT_SIZE) {
+ if (pckt_size > max(max_pcktsz, ICMP_TOOBIG_SIZE)) {
offset = pckt_size - ICMP_TOOBIG_SIZE;
if (bpf_xdp_adjust_tail(xdp, 0 - offset))
return XDP_PASS;
--
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