mirror of
https://github.com/torvalds/linux.git
synced 2024-12-24 20:01:55 +00:00
91bc4822c3
Commit 608cd71a9c ("tc: bpf: generalize pedit action") has added the
possibility to mangle packet data to BPF programs in the tc pipeline.
This patch adds two helpers bpf_l3_csum_replace() and bpf_l4_csum_replace()
for fixing up the protocol checksums after the packet mangling.
It also adds 'flags' argument to bpf_skb_store_bytes() helper to avoid
unnecessary checksum recomputations when BPF programs adjusting l3/l4
checksums and documents all three helpers in uapi header.
Moreover, a sample program is added to show how BPF programs can make use
of the mangle and csum helpers.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
72 lines
2.0 KiB
C
72 lines
2.0 KiB
C
#include <uapi/linux/bpf.h>
|
|
#include <uapi/linux/if_ether.h>
|
|
#include <uapi/linux/if_packet.h>
|
|
#include <uapi/linux/ip.h>
|
|
#include <uapi/linux/in.h>
|
|
#include <uapi/linux/tcp.h>
|
|
#include "bpf_helpers.h"
|
|
|
|
/* compiler workaround */
|
|
#define _htonl __builtin_bswap32
|
|
|
|
static inline void set_dst_mac(struct __sk_buff *skb, char *mac)
|
|
{
|
|
bpf_skb_store_bytes(skb, 0, mac, ETH_ALEN, 1);
|
|
}
|
|
|
|
/* use 1 below for ingress qdisc and 0 for egress */
|
|
#if 0
|
|
#undef ETH_HLEN
|
|
#define ETH_HLEN 0
|
|
#endif
|
|
|
|
#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
|
|
#define TOS_OFF (ETH_HLEN + offsetof(struct iphdr, tos))
|
|
|
|
static inline void set_ip_tos(struct __sk_buff *skb, __u8 new_tos)
|
|
{
|
|
__u8 old_tos = load_byte(skb, TOS_OFF);
|
|
|
|
bpf_l3_csum_replace(skb, IP_CSUM_OFF, htons(old_tos), htons(new_tos), 2);
|
|
bpf_skb_store_bytes(skb, TOS_OFF, &new_tos, sizeof(new_tos), 0);
|
|
}
|
|
|
|
#define TCP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, check))
|
|
#define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr))
|
|
|
|
#define IS_PSEUDO 0x10
|
|
|
|
static inline void set_tcp_ip_src(struct __sk_buff *skb, __u32 new_ip)
|
|
{
|
|
__u32 old_ip = _htonl(load_word(skb, IP_SRC_OFF));
|
|
|
|
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_ip, new_ip, IS_PSEUDO | sizeof(new_ip));
|
|
bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
|
|
bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
|
|
}
|
|
|
|
#define TCP_DPORT_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
|
|
static inline void set_tcp_dest_port(struct __sk_buff *skb, __u16 new_port)
|
|
{
|
|
__u16 old_port = htons(load_half(skb, TCP_DPORT_OFF));
|
|
|
|
bpf_l4_csum_replace(skb, TCP_CSUM_OFF, old_port, new_port, sizeof(new_port));
|
|
bpf_skb_store_bytes(skb, TCP_DPORT_OFF, &new_port, sizeof(new_port), 0);
|
|
}
|
|
|
|
SEC("classifier")
|
|
int bpf_prog1(struct __sk_buff *skb)
|
|
{
|
|
__u8 proto = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));
|
|
long *value;
|
|
|
|
if (proto == IPPROTO_TCP) {
|
|
set_ip_tos(skb, 8);
|
|
set_tcp_ip_src(skb, 0xA010101);
|
|
set_tcp_dest_port(skb, 5001);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
char _license[] SEC("license") = "GPL";
|