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samples: bpf: large eBPF program in C
sockex2_kern.c is purposefully large eBPF program in C. llvm compiles ~200 lines of C code into ~300 eBPF instructions. It's similar to __skb_flow_dissect() to demonstrate that complex packet parsing can be done by eBPF. Then it uses (struct flow_keys)->dst IP address (or hash of ipv6 dst) to keep stats of number of packets per IP. User space loads eBPF program, attaches it to loopback interface and prints dest_ip->#packets stats every second. Usage: $sudo samples/bpf/sockex2 ip 127.0.0.1 count 19 ip 127.0.0.1 count 178115 ip 127.0.0.1 count 369437 ip 127.0.0.1 count 559841 ip 127.0.0.1 count 750539 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
David S. Miller
parent
a80857822b
commit
fbe3310840
@ -5,20 +5,24 @@ obj- := dummy.o
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hostprogs-y := test_verifier test_maps
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hostprogs-y += sock_example
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hostprogs-y += sockex1
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hostprogs-y += sockex2
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test_verifier-objs := test_verifier.o libbpf.o
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test_maps-objs := test_maps.o libbpf.o
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sock_example-objs := sock_example.o libbpf.o
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sockex1-objs := bpf_load.o libbpf.o sockex1_user.o
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sockex2-objs := bpf_load.o libbpf.o sockex2_user.o
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# Tell kbuild to always build the programs
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always := $(hostprogs-y)
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always += sockex1_kern.o
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always += sockex2_kern.o
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HOSTCFLAGS += -I$(objtree)/usr/include
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HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable
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HOSTLOADLIBES_sockex1 += -lelf
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HOSTLOADLIBES_sockex2 += -lelf
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# point this to your LLVM backend with bpf support
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LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc
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215
samples/bpf/sockex2_kern.c
Normal file
215
samples/bpf/sockex2_kern.c
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@ -0,0 +1,215 @@
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#include <uapi/linux/bpf.h>
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#include "bpf_helpers.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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#define IP_MF 0x2000
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#define IP_OFFSET 0x1FFF
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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_keys {
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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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__u16 thoff;
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__u8 ip_proto;
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};
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static inline int proto_ports_offset(__u64 proto)
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{
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switch (proto) {
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case IPPROTO_TCP:
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case IPPROTO_UDP:
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case IPPROTO_DCCP:
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case IPPROTO_ESP:
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case IPPROTO_SCTP:
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case IPPROTO_UDPLITE:
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return 0;
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case IPPROTO_AH:
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return 4;
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default:
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return 0;
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}
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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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static inline __u64 parse_ip(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto,
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struct flow_keys *flow)
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{
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__u64 verlen;
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if (unlikely(ip_is_fragment(skb, nhoff)))
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*ip_proto = 0;
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else
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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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flow->src = load_word(skb, nhoff + offsetof(struct iphdr, saddr));
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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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if (likely(verlen == 0x45))
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nhoff += 20;
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else
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nhoff += (verlen & 0xF) << 2;
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return nhoff;
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}
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static inline __u64 parse_ipv6(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto,
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struct flow_keys *flow)
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{
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*ip_proto = load_byte(skb,
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nhoff + offsetof(struct ipv6hdr, nexthdr));
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flow->src = ipv6_addr_hash(skb,
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nhoff + offsetof(struct ipv6hdr, saddr));
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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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return nhoff;
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}
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static inline bool flow_dissector(struct sk_buff *skb, struct flow_keys *flow)
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{
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__u64 nhoff = ETH_HLEN;
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__u64 ip_proto;
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__u64 proto = load_half(skb, 12);
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int poff;
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if (proto == ETH_P_8021AD) {
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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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}
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if (proto == ETH_P_8021Q) {
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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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}
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if (likely(proto == ETH_P_IP))
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nhoff = parse_ip(skb, nhoff, &ip_proto, flow);
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else if (proto == ETH_P_IPV6)
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nhoff = parse_ipv6(skb, nhoff, &ip_proto, flow);
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else
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return false;
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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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__u64 gre_flags = load_half(skb,
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nhoff + offsetof(struct gre_hdr, flags));
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__u64 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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proto = gre_proto;
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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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if (proto == ETH_P_8021Q) {
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proto = load_half(skb,
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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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}
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if (proto == ETH_P_IP)
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nhoff = parse_ip(skb, nhoff, &ip_proto, flow);
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else if (proto == ETH_P_IPV6)
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nhoff = parse_ipv6(skb, nhoff, &ip_proto, flow);
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else
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return false;
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break;
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}
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case IPPROTO_IPIP:
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nhoff = parse_ip(skb, nhoff, &ip_proto, flow);
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break;
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case IPPROTO_IPV6:
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nhoff = parse_ipv6(skb, nhoff, &ip_proto, flow);
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break;
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default:
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break;
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}
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flow->ip_proto = ip_proto;
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poff = proto_ports_offset(ip_proto);
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if (poff >= 0) {
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nhoff += poff;
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flow->ports = load_word(skb, nhoff);
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}
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flow->thoff = (__u16) nhoff;
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return true;
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}
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struct bpf_map_def SEC("maps") hash_map = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(__be32),
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.value_size = sizeof(long),
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.max_entries = 1024,
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};
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SEC("socket2")
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int bpf_prog2(struct sk_buff *skb)
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{
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struct flow_keys flow;
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long *value;
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u32 key;
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if (!flow_dissector(skb, &flow))
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return 0;
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key = flow.dst;
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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, 1);
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} else {
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long val = 1;
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bpf_map_update_elem(&hash_map, &key, &val, BPF_ANY);
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}
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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44
samples/bpf/sockex2_user.c
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44
samples/bpf/sockex2_user.c
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@ -0,0 +1,44 @@
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#include <stdio.h>
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#include <assert.h>
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#include <linux/bpf.h>
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#include "libbpf.h"
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#include "bpf_load.h"
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#include <unistd.h>
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#include <arpa/inet.h>
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int main(int ac, char **argv)
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{
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char filename[256];
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FILE *f;
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int i, sock;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 1;
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}
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sock = open_raw_sock("lo");
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assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, prog_fd,
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sizeof(prog_fd[0])) == 0);
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f = popen("ping -c5 localhost", "r");
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(void) f;
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for (i = 0; i < 5; i++) {
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int key = 0, next_key;
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long long value;
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while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {
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bpf_lookup_elem(map_fd[0], &next_key, &value);
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printf("ip %s count %lld\n",
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inet_ntoa((struct in_addr){htonl(next_key)}),
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value);
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key = next_key;
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}
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sleep(1);
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}
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return 0;
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}
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