linux/samples/bpf/xdp1_kern.c
Jesper Dangaard Brouer 60548b825b samples/bpf: xdp1 and xdp2 reduce XDPBUFSIZE to 60
Default samples/pktgen scripts send 60 byte packets as hardware adds
4-bytes FCS checksum, which fulfils minimum Ethernet 64 bytes frame
size.

XDP layer will not necessary have access to the 4-bytes FCS checksum.

This leads to bpf_xdp_load_bytes() failing as it tries to copy 64-bytes
from an XDP packet that only have 60-bytes available.

Fixes: 7722517422 ("samples/bpf: fixup some tools to be able to support xdp multibuffer")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/bpf/168545704139.2996228.2516528552939485216.stgit@firesoul
2023-05-31 13:08:28 +02:00

101 lines
2.2 KiB
C

/* Copyright (c) 2016 PLUMgrid
*
* 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.
*/
#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>
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__type(key, u32);
__type(value, long);
__uint(max_entries, 256);
} rxcnt SEC(".maps");
static int parse_ipv4(void *data, u64 nh_off, void *data_end)
{
struct iphdr *iph = data + nh_off;
if (iph + 1 > data_end)
return 0;
return iph->protocol;
}
static int parse_ipv6(void *data, u64 nh_off, void *data_end)
{
struct ipv6hdr *ip6h = data + nh_off;
if (ip6h + 1 > data_end)
return 0;
return ip6h->nexthdr;
}
#define XDPBUFSIZE 60
SEC("xdp.frags")
int xdp_prog1(struct xdp_md *ctx)
{
__u8 pkt[XDPBUFSIZE] = {};
void *data_end = &pkt[XDPBUFSIZE-1];
void *data = pkt;
struct ethhdr *eth = data;
int rc = XDP_DROP;
long *value;
u16 h_proto;
u64 nh_off;
u32 ipproto;
if (bpf_xdp_load_bytes(ctx, 0, pkt, sizeof(pkt)))
return rc;
nh_off = sizeof(*eth);
if (data + nh_off > data_end)
return rc;
h_proto = eth->h_proto;
/* Handle VLAN tagged packet */
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
/* Handle double VLAN tagged packet */
if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
struct vlan_hdr *vhdr;
vhdr = data + nh_off;
nh_off += sizeof(struct vlan_hdr);
if (data + nh_off > data_end)
return rc;
h_proto = vhdr->h_vlan_encapsulated_proto;
}
if (h_proto == htons(ETH_P_IP))
ipproto = parse_ipv4(data, nh_off, data_end);
else if (h_proto == htons(ETH_P_IPV6))
ipproto = parse_ipv6(data, nh_off, data_end);
else
ipproto = 0;
value = bpf_map_lookup_elem(&rxcnt, &ipproto);
if (value)
*value += 1;
return rc;
}
char _license[] SEC("license") = "GPL";