294 lines
6.2 KiB
C
294 lines
6.2 KiB
C
/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <uapi/linux/bpf.h>
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#include <uapi/linux/in.h>
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#include <uapi/linux/if.h>
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#include <uapi/linux/if_ether.h>
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#include <uapi/linux/ip.h>
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#include <uapi/linux/ipv6.h>
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#include <uapi/linux/if_tunnel.h>
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#include <uapi/linux/mpls.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_legacy.h"
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#define IP_MF 0x2000
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#define IP_OFFSET 0x1FFF
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#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
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struct {
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__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
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__uint(key_size, sizeof(u32));
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__uint(value_size, sizeof(u32));
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__uint(max_entries, 8);
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} jmp_table SEC(".maps");
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#define PARSE_VLAN 1
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#define PARSE_MPLS 2
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#define PARSE_IP 3
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#define PARSE_IPV6 4
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/* Protocol dispatch routine. It tail-calls next BPF program depending
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* on eth proto. Note, we could have used ...
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*
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* bpf_tail_call(skb, &jmp_table, proto);
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*
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* ... but it would need large prog_array and cannot be optimised given
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* the map key is not static.
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*/
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static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto)
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{
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switch (proto) {
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case ETH_P_8021Q:
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case ETH_P_8021AD:
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bpf_tail_call(skb, &jmp_table, PARSE_VLAN);
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break;
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case ETH_P_MPLS_UC:
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case ETH_P_MPLS_MC:
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bpf_tail_call(skb, &jmp_table, PARSE_MPLS);
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break;
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case ETH_P_IP:
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bpf_tail_call(skb, &jmp_table, PARSE_IP);
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break;
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case ETH_P_IPV6:
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bpf_tail_call(skb, &jmp_table, PARSE_IPV6);
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break;
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}
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}
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struct vlan_hdr {
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__be16 h_vlan_TCI;
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__be16 h_vlan_encapsulated_proto;
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};
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struct flow_key_record {
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__be32 src;
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__be32 dst;
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union {
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__be32 ports;
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__be16 port16[2];
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};
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__u32 ip_proto;
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};
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static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff)
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{
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return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off))
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& (IP_MF | IP_OFFSET);
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}
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static inline __u32 ipv6_addr_hash(struct __sk_buff *ctx, __u64 off)
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{
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__u64 w0 = load_word(ctx, off);
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__u64 w1 = load_word(ctx, off + 4);
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__u64 w2 = load_word(ctx, off + 8);
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__u64 w3 = load_word(ctx, off + 12);
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return (__u32)(w0 ^ w1 ^ w2 ^ w3);
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}
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struct globals {
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struct flow_key_record flow;
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};
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, __u32);
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__type(value, struct globals);
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__uint(max_entries, 32);
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} percpu_map SEC(".maps");
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/* user poor man's per_cpu until native support is ready */
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static struct globals *this_cpu_globals(void)
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{
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u32 key = bpf_get_smp_processor_id();
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return bpf_map_lookup_elem(&percpu_map, &key);
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}
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/* some simple stats for user space consumption */
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struct pair {
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__u64 packets;
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__u64 bytes;
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};
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__type(key, struct flow_key_record);
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__type(value, struct pair);
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__uint(max_entries, 1024);
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} hash_map SEC(".maps");
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static void update_stats(struct __sk_buff *skb, struct globals *g)
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{
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struct flow_key_record key = g->flow;
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struct pair *value;
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value = bpf_map_lookup_elem(&hash_map, &key);
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if (value) {
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__sync_fetch_and_add(&value->packets, 1);
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__sync_fetch_and_add(&value->bytes, skb->len);
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} else {
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struct pair val = {1, skb->len};
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bpf_map_update_elem(&hash_map, &key, &val, BPF_ANY);
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}
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}
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static __always_inline void parse_ip_proto(struct __sk_buff *skb,
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struct globals *g, __u32 ip_proto)
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{
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__u32 nhoff = skb->cb[0];
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int poff;
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switch (ip_proto) {
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case IPPROTO_GRE: {
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struct gre_hdr {
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__be16 flags;
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__be16 proto;
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};
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__u32 gre_flags = load_half(skb,
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nhoff + offsetof(struct gre_hdr, flags));
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__u32 gre_proto = load_half(skb,
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nhoff + offsetof(struct gre_hdr, proto));
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if (gre_flags & (GRE_VERSION|GRE_ROUTING))
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break;
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nhoff += 4;
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if (gre_flags & GRE_CSUM)
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nhoff += 4;
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if (gre_flags & GRE_KEY)
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nhoff += 4;
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if (gre_flags & GRE_SEQ)
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nhoff += 4;
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skb->cb[0] = nhoff;
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parse_eth_proto(skb, gre_proto);
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break;
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}
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case IPPROTO_IPIP:
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parse_eth_proto(skb, ETH_P_IP);
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break;
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case IPPROTO_IPV6:
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parse_eth_proto(skb, ETH_P_IPV6);
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break;
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case IPPROTO_TCP:
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case IPPROTO_UDP:
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g->flow.ports = load_word(skb, nhoff);
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case IPPROTO_ICMP:
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g->flow.ip_proto = ip_proto;
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update_stats(skb, g);
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break;
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default:
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break;
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}
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}
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PROG(PARSE_IP)(struct __sk_buff *skb)
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{
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struct globals *g = this_cpu_globals();
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__u32 nhoff, verlen, ip_proto;
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if (!g)
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return 0;
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nhoff = skb->cb[0];
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if (unlikely(ip_is_fragment(skb, nhoff)))
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return 0;
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ip_proto = load_byte(skb, nhoff + offsetof(struct iphdr, protocol));
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if (ip_proto != IPPROTO_GRE) {
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g->flow.src = load_word(skb, nhoff + offsetof(struct iphdr, saddr));
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g->flow.dst = load_word(skb, nhoff + offsetof(struct iphdr, daddr));
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}
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verlen = load_byte(skb, nhoff + 0/*offsetof(struct iphdr, ihl)*/);
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nhoff += (verlen & 0xF) << 2;
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skb->cb[0] = nhoff;
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parse_ip_proto(skb, g, ip_proto);
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return 0;
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}
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PROG(PARSE_IPV6)(struct __sk_buff *skb)
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{
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struct globals *g = this_cpu_globals();
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__u32 nhoff, ip_proto;
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if (!g)
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return 0;
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nhoff = skb->cb[0];
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ip_proto = load_byte(skb,
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nhoff + offsetof(struct ipv6hdr, nexthdr));
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g->flow.src = ipv6_addr_hash(skb,
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nhoff + offsetof(struct ipv6hdr, saddr));
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g->flow.dst = ipv6_addr_hash(skb,
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nhoff + offsetof(struct ipv6hdr, daddr));
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nhoff += sizeof(struct ipv6hdr);
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skb->cb[0] = nhoff;
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parse_ip_proto(skb, g, ip_proto);
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return 0;
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}
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PROG(PARSE_VLAN)(struct __sk_buff *skb)
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{
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__u32 nhoff, proto;
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nhoff = skb->cb[0];
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proto = load_half(skb, nhoff + offsetof(struct vlan_hdr,
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h_vlan_encapsulated_proto));
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nhoff += sizeof(struct vlan_hdr);
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skb->cb[0] = nhoff;
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parse_eth_proto(skb, proto);
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return 0;
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}
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PROG(PARSE_MPLS)(struct __sk_buff *skb)
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{
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__u32 nhoff, label;
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nhoff = skb->cb[0];
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label = load_word(skb, nhoff);
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nhoff += sizeof(struct mpls_label);
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skb->cb[0] = nhoff;
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if (label & MPLS_LS_S_MASK) {
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__u8 verlen = load_byte(skb, nhoff);
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if ((verlen & 0xF0) == 4)
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parse_eth_proto(skb, ETH_P_IP);
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else
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parse_eth_proto(skb, ETH_P_IPV6);
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} else {
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parse_eth_proto(skb, ETH_P_MPLS_UC);
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}
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return 0;
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}
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SEC("socket/0")
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int main_prog(struct __sk_buff *skb)
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{
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__u32 nhoff = ETH_HLEN;
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__u32 proto = load_half(skb, 12);
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skb->cb[0] = nhoff;
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parse_eth_proto(skb, proto);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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