#include <stdbool.h>
#include <stdint.h>
#include <linux/stddef.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/bpf.h>
#include <linux/types.h>
#include <bpf/bpf_endian.h>
#include <bpf/bpf_helpers.h>
enum pkt_parse_err {
NO_ERR,
BAD_IP6_HDR,
BAD_IP4GUE_HDR,
BAD_IP6GUE_HDR,
};
enum pkt_flag {
TUNNEL = 0x1,
TCP_SYN = 0x2,
QUIC_INITIAL_FLAG = 0x4,
TCP_ACK = 0x8,
TCP_RST = 0x10
};
struct v4_lpm_key {
__u32 prefixlen;
__u32 src;
};
struct v4_lpm_val {
struct v4_lpm_key key;
__u8 val;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 16);
__type(key, struct in6_addr);
__type(value, bool);
} v6_addr_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 16);
__type(key, __u32);
__type(value, bool);
} v4_addr_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_LPM_TRIE);
__uint(max_entries, 16);
__uint(key_size, sizeof(struct v4_lpm_key));
__uint(value_size, sizeof(struct v4_lpm_val));
__uint(map_flags, BPF_F_NO_PREALLOC);
} v4_lpm_val_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 16);
__type(key, int);
__type(value, __u8);
} tcp_port_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 16);
__type(key, int);
__type(value, __u16);
} udp_port_map SEC(".maps");
enum ip_type { V4 = 1, V6 = 2 };
struct fw_match_info {
__u8 v4_src_ip_match;
__u8 v6_src_ip_match;
__u8 v4_src_prefix_match;
__u8 v4_dst_prefix_match;
__u8 tcp_dp_match;
__u16 udp_sp_match;
__u16 udp_dp_match;
bool is_tcp;
bool is_tcp_syn;
};
struct pkt_info {
enum ip_type type;
union {
struct iphdr *ipv4;
struct ipv6hdr *ipv6;
} ip;
int sport;
int dport;
__u16 trans_hdr_offset;
__u8 proto;
__u8 flags;
};
static __always_inline struct ethhdr *parse_ethhdr(void *data, void *data_end)
{
struct ethhdr *eth = data;
if (eth + 1 > data_end)
return NULL;
return eth;
}
static __always_inline __u8 filter_ipv6_addr(const struct in6_addr *ipv6addr)
{
__u8 *leaf;
leaf = bpf_map_lookup_elem(&v6_addr_map, ipv6addr);
return leaf ? *leaf : 0;
}
static __always_inline __u8 filter_ipv4_addr(const __u32 ipaddr)
{
__u8 *leaf;
leaf = bpf_map_lookup_elem(&v4_addr_map, &ipaddr);
return leaf ? *leaf : 0;
}
static __always_inline __u8 filter_ipv4_lpm(const __u32 ipaddr)
{
struct v4_lpm_key v4_key = {};
struct v4_lpm_val *lpm_val;
v4_key.src = ipaddr;
v4_key.prefixlen = 32;
lpm_val = bpf_map_lookup_elem(&v4_lpm_val_map, &v4_key);
return lpm_val ? lpm_val->val : 0;
}
static __always_inline void
filter_src_dst_ip(struct pkt_info* info, struct fw_match_info* match_info)
{
if (info->type == V6) {
match_info->v6_src_ip_match =
filter_ipv6_addr(&info->ip.ipv6->saddr);
} else if (info->type == V4) {
match_info->v4_src_ip_match =
filter_ipv4_addr(info->ip.ipv4->saddr);
match_info->v4_src_prefix_match =
filter_ipv4_lpm(info->ip.ipv4->saddr);
match_info->v4_dst_prefix_match =
filter_ipv4_lpm(info->ip.ipv4->daddr);
}
}
static __always_inline void *
get_transport_hdr(__u16 offset, void *data, void *data_end)
{
if (offset > 255 || data + offset > data_end)
return NULL;
return data + offset;
}
static __always_inline bool tcphdr_only_contains_flag(struct tcphdr *tcp,
__u32 FLAG)
{
return (tcp_flag_word(tcp) &
(TCP_FLAG_ACK | TCP_FLAG_RST | TCP_FLAG_SYN | TCP_FLAG_FIN)) == FLAG;
}
static __always_inline void set_tcp_flags(struct pkt_info *info,
struct tcphdr *tcp) {
if (tcphdr_only_contains_flag(tcp, TCP_FLAG_SYN))
info->flags |= TCP_SYN;
else if (tcphdr_only_contains_flag(tcp, TCP_FLAG_ACK))
info->flags |= TCP_ACK;
else if (tcphdr_only_contains_flag(tcp, TCP_FLAG_RST))
info->flags |= TCP_RST;
}
static __always_inline bool
parse_tcp(struct pkt_info *info, void *transport_hdr, void *data_end)
{
struct tcphdr *tcp = transport_hdr;
if (tcp + 1 > data_end)
return false;
info->sport = bpf_ntohs(tcp->source);
info->dport = bpf_ntohs(tcp->dest);
set_tcp_flags(info, tcp);
return true;
}
static __always_inline bool
parse_udp(struct pkt_info *info, void *transport_hdr, void *data_end)
{
struct udphdr *udp = transport_hdr;
if (udp + 1 > data_end)
return false;
info->sport = bpf_ntohs(udp->source);
info->dport = bpf_ntohs(udp->dest);
return true;
}
static __always_inline __u8 filter_tcp_port(int port)
{
__u8 *leaf = bpf_map_lookup_elem(&tcp_port_map, &port);
return leaf ? *leaf : 0;
}
static __always_inline __u16 filter_udp_port(int port)
{
__u16 *leaf = bpf_map_lookup_elem(&udp_port_map, &port);
return leaf ? *leaf : 0;
}
static __always_inline bool
filter_transport_hdr(void *transport_hdr, void *data_end,
struct pkt_info *info, struct fw_match_info *match_info)
{
if (info->proto == IPPROTO_TCP) {
if (!parse_tcp(info, transport_hdr, data_end))
return false;
match_info->is_tcp = true;
match_info->is_tcp_syn = (info->flags & TCP_SYN) > 0;
match_info->tcp_dp_match = filter_tcp_port(info->dport);
} else if (info->proto == IPPROTO_UDP) {
if (!parse_udp(info, transport_hdr, data_end))
return false;
match_info->udp_dp_match = filter_udp_port(info->dport);
match_info->udp_sp_match = filter_udp_port(info->sport);
}
return true;
}
static __always_inline __u8
parse_gue_v6(struct pkt_info *info, struct ipv6hdr *ip6h, void *data_end)
{
struct udphdr *udp = (struct udphdr *)(ip6h + 1);
void *encap_data = udp + 1;
if (udp + 1 > data_end)
return BAD_IP6_HDR;
if (udp->dest != bpf_htons(6666))
return NO_ERR;
info->flags |= TUNNEL;
if (encap_data + 1 > data_end)
return BAD_IP6GUE_HDR;
if (*(__u8 *)encap_data & 0x30) {
struct ipv6hdr *inner_ip6h = encap_data;
if (inner_ip6h + 1 > data_end)
return BAD_IP6GUE_HDR;
info->type = V6;
info->proto = inner_ip6h->nexthdr;
info->ip.ipv6 = inner_ip6h;
info->trans_hdr_offset += sizeof(struct ipv6hdr) + sizeof(struct udphdr);
} else {
struct iphdr *inner_ip4h = encap_data;
if (inner_ip4h + 1 > data_end)
return BAD_IP6GUE_HDR;
info->type = V4;
info->proto = inner_ip4h->protocol;
info->ip.ipv4 = inner_ip4h;
info->trans_hdr_offset += sizeof(struct iphdr) + sizeof(struct udphdr);
}
return NO_ERR;
}
static __always_inline __u8 parse_ipv6_gue(struct pkt_info *info,
void *data, void *data_end)
{
struct ipv6hdr *ip6h = data + sizeof(struct ethhdr);
if (ip6h + 1 > data_end)
return BAD_IP6_HDR;
info->proto = ip6h->nexthdr;
info->ip.ipv6 = ip6h;
info->type = V6;
info->trans_hdr_offset = sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
if (info->proto == IPPROTO_UDP)
return parse_gue_v6(info, ip6h, data_end);
return NO_ERR;
}
SEC("xdp")
int edgewall(struct xdp_md *ctx)
{
void *data_end = (void *)(long)(ctx->data_end);
void *data = (void *)(long)(ctx->data);
struct fw_match_info match_info = {};
struct pkt_info info = {};
void *transport_hdr;
struct ethhdr *eth;
bool filter_res;
__u32 proto;
eth = parse_ethhdr(data, data_end);
if (!eth)
return XDP_DROP;
proto = eth->h_proto;
if (proto != bpf_htons(ETH_P_IPV6))
return XDP_DROP;
if (parse_ipv6_gue(&info, data, data_end))
return XDP_DROP;
if (info.proto == IPPROTO_ICMPV6)
return XDP_PASS;
if (info.proto != IPPROTO_TCP && info.proto != IPPROTO_UDP)
return XDP_DROP;
filter_src_dst_ip(&info, &match_info);
transport_hdr = get_transport_hdr(info.trans_hdr_offset, data,
data_end);
if (!transport_hdr)
return XDP_DROP;
filter_res = filter_transport_hdr(transport_hdr, data_end,
&info, &match_info);
if (!filter_res)
return XDP_DROP;
if (match_info.is_tcp && !match_info.is_tcp_syn)
return XDP_PASS;
return XDP_DROP;
}
char LICENSE[] SEC("license") = "GPL";
