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Mitm
mihomo/component/ebpf/bpf/redir.c
zhudan 31f4d20477 support ebpf
2022-07-29 09:08:35 +08:00

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#include <stdint.h>
#include <stdbool.h>
//#include <linux/types.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
//#include <linux/if_packet.h>
//#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/in.h>
#include <linux/tcp.h>
//#include <linux/udp.h>
#include <linux/pkt_cls.h>
#include "bpf_endian.h"
#include "bpf_helpers.h"
#define IP_CSUM_OFF (ETH_HLEN + offsetof(struct iphdr, check))
#define IP_DST_OFF (ETH_HLEN + offsetof(struct iphdr, daddr))
#define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr))
#define IP_PROTO_OFF (ETH_HLEN + offsetof(struct iphdr, protocol))
#define TCP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, check))
#define TCP_SRC_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, source))
#define TCP_DST_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct tcphdr, dest))
//#define UDP_CSUM_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct udphdr, check))
//#define UDP_SRC_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct udphdr, source))
//#define UDP_DST_OFF (ETH_HLEN + sizeof(struct iphdr) + offsetof(struct udphdr, dest))
#define IS_PSEUDO 0x10
struct origin_info {
__be32 ip;
__be16 port;
__u16 pad;
};
struct origin_info *origin_info_unused __attribute__((unused));
struct redir_info {
__be32 sip;
__be32 dip;
__be16 sport;
__be16 dport;
};
struct redir_info *redir_info_unused __attribute__((unused));
struct {
__uint(type, BPF_MAP_TYPE_LRU_HASH);
__type(key, struct redir_info);
__type(value, struct origin_info);
__uint(max_entries, 65535);
__uint(pinning, LIBBPF_PIN_BY_NAME);
} pair_original_dst_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, __u32);
__type(value, __u32);
__uint(max_entries, 3);
__uint(pinning, LIBBPF_PIN_BY_NAME);
} redir_params_map SEC(".maps");
static __always_inline int rewrite_ip(struct __sk_buff *skb, __be32 new_ip, bool is_dest) {
int ret, off = 0, flags = IS_PSEUDO;
__be32 old_ip;
if (is_dest)
ret = bpf_skb_load_bytes(skb, IP_DST_OFF, &old_ip, 4);
else
ret = bpf_skb_load_bytes(skb, IP_SRC_OFF, &old_ip, 4);
if (ret < 0) {
return ret;
}
off = TCP_CSUM_OFF;
// __u8 proto;
//
// ret = bpf_skb_load_bytes(skb, IP_PROTO_OFF, &proto, 1);
// if (ret < 0) {
// return BPF_DROP;
// }
//
// switch (proto) {
// case IPPROTO_TCP:
// off = TCP_CSUM_OFF;
// break;
//
// case IPPROTO_UDP:
// off = UDP_CSUM_OFF;
// flags |= BPF_F_MARK_MANGLED_0;
// break;
//
// case IPPROTO_ICMPV6:
// off = offsetof(struct icmp6hdr, icmp6_cksum);
// break;
// }
//
// if (off) {
ret = bpf_l4_csum_replace(skb, off, old_ip, new_ip, flags | sizeof(new_ip));
if (ret < 0) {
return ret;
}
// }
ret = bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip));
if (ret < 0) {
return ret;
}
if (is_dest)
ret = bpf_skb_store_bytes(skb, IP_DST_OFF, &new_ip, sizeof(new_ip), 0);
else
ret = bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0);
if (ret < 0) {
return ret;
}
return 1;
}
static __always_inline int rewrite_port(struct __sk_buff *skb, __be16 new_port, bool is_dest) {
int ret, off = 0;
__be16 old_port;
if (is_dest)
ret = bpf_skb_load_bytes(skb, TCP_DST_OFF, &old_port, 2);
else
ret = bpf_skb_load_bytes(skb, TCP_SRC_OFF, &old_port, 2);
if (ret < 0) {
return ret;
}
off = TCP_CSUM_OFF;
ret = bpf_l4_csum_replace(skb, off, old_port, new_port, sizeof(new_port));
if (ret < 0) {
return ret;
}
if (is_dest)
ret = bpf_skb_store_bytes(skb, TCP_DST_OFF, &new_port, sizeof(new_port), 0);
else
ret = bpf_skb_store_bytes(skb, TCP_SRC_OFF, &new_port, sizeof(new_port), 0);
if (ret < 0) {
return ret;
}
return 1;
}
static __always_inline bool is_lan_ip(__be32 addr) {
if (addr == 0xffffffff)
return true;
__u8 fist = (__u8)(addr & 0xff);
if (fist == 127 || fist == 10)
return true;
__u8 second = (__u8)((addr >> 8) & 0xff);
if (fist == 172 && second >= 16 && second <= 31)
return true;
if (fist == 192 && second == 168)
return true;
return false;
}
SEC("tc_clash_auto_redir_ingress")
int tc_redir_ingress_func(struct __sk_buff *skb) {
void *data = (void *)(long)skb->data;
void *data_end = (void *)(long)skb->data_end;
struct ethhdr *eth = data;
if ((void *)(eth + 1) > data_end)
return TC_ACT_OK;
if (eth->h_proto != bpf_htons(ETH_P_IP))
return TC_ACT_OK;
struct iphdr *iph = (struct iphdr *)(eth + 1);
if ((void *)(iph + 1) > data_end)
return TC_ACT_OK;
__u32 key = 0, *route_index, *redir_ip, *redir_port;
route_index = bpf_map_lookup_elem(&redir_params_map, &key);
if (!route_index)
return TC_ACT_OK;
if (iph->protocol == IPPROTO_ICMP && *route_index != 0)
return bpf_redirect(*route_index, 0);
if (iph->protocol != IPPROTO_TCP)
return TC_ACT_OK;
struct tcphdr *tcph = (struct tcphdr *)(iph + 1);
if ((void *)(tcph + 1) > data_end)
return TC_ACT_SHOT;
key = 1;
redir_ip = bpf_map_lookup_elem(&redir_params_map, &key);
if (!redir_ip)
return TC_ACT_OK;
key = 2;
redir_port = bpf_map_lookup_elem(&redir_params_map, &key);
if (!redir_port)
return TC_ACT_OK;
__be32 new_ip = bpf_htonl(*redir_ip);
__be16 new_port = bpf_htonl(*redir_port) >> 16;
__be32 old_ip = iph->daddr;
__be16 old_port = tcph->dest;
if (old_ip == new_ip || is_lan_ip(old_ip) || bpf_ntohs(old_port) == 53) {
return TC_ACT_OK;
}
struct redir_info p_key = {
.sip = iph->saddr,
.sport = tcph->source,
.dip = new_ip,
.dport = new_port,
};
if (tcph->syn && !tcph->ack) {
struct origin_info origin = {
.ip = old_ip,
.port = old_port,
};
bpf_map_update_elem(&pair_original_dst_map, &p_key, &origin, BPF_NOEXIST);
if (rewrite_ip(skb, new_ip, true) < 0) {
return TC_ACT_SHOT;
}
if (rewrite_port(skb, new_port, true) < 0) {
return TC_ACT_SHOT;
}
} else {
struct origin_info *origin = bpf_map_lookup_elem(&pair_original_dst_map, &p_key);
if (!origin) {
return TC_ACT_OK;
}
if (rewrite_ip(skb, new_ip, true) < 0) {
return TC_ACT_SHOT;
}
if (rewrite_port(skb, new_port, true) < 0) {
return TC_ACT_SHOT;
}
}
return TC_ACT_OK;
}
SEC("tc_clash_auto_redir_egress")
int tc_redir_egress_func(struct __sk_buff *skb) {
void *data = (void *)(long)skb->data;
void *data_end = (void *)(long)skb->data_end;
struct ethhdr *eth = data;
if ((void *)(eth + 1) > data_end)
return TC_ACT_OK;
if (eth->h_proto != bpf_htons(ETH_P_IP))
return TC_ACT_OK;
__u32 key = 0, *redir_ip, *redir_port; // *clash_mark
// clash_mark = bpf_map_lookup_elem(&redir_params_map, &key);
// if (clash_mark && *clash_mark != 0 && *clash_mark == skb->mark)
// return TC_ACT_OK;
struct iphdr *iph = (struct iphdr *)(eth + 1);
if ((void *)(iph + 1) > data_end)
return TC_ACT_OK;
if (iph->protocol != IPPROTO_TCP)
return TC_ACT_OK;
struct tcphdr *tcph = (struct tcphdr *)(iph + 1);
if ((void *)(tcph + 1) > data_end)
return TC_ACT_SHOT;
key = 1;
redir_ip = bpf_map_lookup_elem(&redir_params_map, &key);
if (!redir_ip)
return TC_ACT_OK;
key = 2;
redir_port = bpf_map_lookup_elem(&redir_params_map, &key);
if (!redir_port)
return TC_ACT_OK;
__be32 new_ip = bpf_htonl(*redir_ip);
__be16 new_port = bpf_htonl(*redir_port) >> 16;
__be32 old_ip = iph->saddr;
__be16 old_port = tcph->source;
if (old_ip != new_ip || old_port != new_port) {
return TC_ACT_OK;
}
struct redir_info p_key = {
.sip = iph->daddr,
.sport = tcph->dest,
.dip = iph->saddr,
.dport = tcph->source,
};
struct origin_info *origin = bpf_map_lookup_elem(&pair_original_dst_map, &p_key);
if (!origin) {
return TC_ACT_OK;
}
if (tcph->fin && tcph->ack) {
bpf_map_delete_elem(&pair_original_dst_map, &p_key);
}
if (rewrite_ip(skb, origin->ip, false) < 0) {
return TC_ACT_SHOT;
}
if (rewrite_port(skb, origin->port, false) < 0) {
return TC_ACT_SHOT;
}
return TC_ACT_OK;
}
char _license[] SEC("license") = "GPL";
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