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feat: allow capture ipv6 packet #586

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merged 3 commits into from
Aug 11, 2024
Merged

feat: allow capture ipv6 packet #586

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82d66f7
ipv6
yuweizzz Aug 7, 2024
4d44cd7
fix spaces
yuweizzz Aug 7, 2024
f9ba998
update makefile
yuweizzz Aug 7, 2024
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2 changes: 1 addition & 1 deletion Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -198,7 +198,7 @@ $(TARGET_LIBPCAP):
CC=$(CMD_CC_PREFIX)$(CMD_CC) AR=$(CMD_AR_PREFIX)$(CMD_AR) CFLAGS="-O2 -g -gdwarf-4 -static" ./configure --disable-rdma --disable-shared --disable-usb \
--disable-netmap --disable-bluetooth --disable-dbus --without-libnl \
--without-dpdk --without-dag --without-septel --without-snf \
--without-gcc --with-pcap=linux --disable-ipv6\
--without-gcc --with-pcap=linux \
--without-turbocap --host=$(LIBPCAP_ARCH) && \
CC=$(CMD_CC_PREFIX)$(CMD_CC) AR=$(CMD_AR_PREFIX)$(CMD_AR) make

Expand Down
1 change: 1 addition & 0 deletions kern/common.h
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Expand Up @@ -47,6 +47,7 @@
///////// for TC & XDP ebpf programs in tc.h
#define TC_ACT_OK 0
#define ETH_P_IP 0x0800 /* Internet Protocol packet */
#define ETH_P_IPV6 0x86DD
#define SKB_MAX_DATA_SIZE 2048

// .rodata section bug via : https://github.com/gojue/ecapture/issues/39
Expand Down
16 changes: 15 additions & 1 deletion kern/ecapture.h
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Expand Up @@ -71,8 +71,22 @@ struct tcphdr {
__be16 dest;
};

struct ipv6hdr {
// __u8 priority: 4;
// __u8 version: 4;
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// __u8 flow_lbl[3];
// __be16 payload_len;
__u8 filler[7];
__u8 nexthdr;
__u8 hop_limit;
// struct in6_addr saddr;
// struct in6_addr daddr;
__u32 saddr[4];
__u32 daddr[4];
};

#endif

#include "common.h"

#endif
#endif
157 changes: 102 additions & 55 deletions kern/tc.h
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Expand Up @@ -37,8 +37,8 @@ struct net_id_t {
u32 src_ip4;
u32 dst_port;
u32 dst_ip4;
// u32 src_ip6[4];
// u32 dst_ip6[4];
u32 src_ip6[4];
u32 dst_ip6[4];
};

struct net_ctx_t {
Expand Down Expand Up @@ -147,54 +147,90 @@ static __always_inline int capture_packets(struct __sk_buff *skb, bool is_ingres
return TC_ACT_OK;
}

// filter out non-IP packets
// TODO support IPv6
if (eth->h_proto != bpf_htons(ETH_P_IP)) {
return TC_ACT_OK;
}
l4_hdr_off = sizeof(struct ethhdr) + sizeof(struct iphdr);
if (!skb_revalidate_data(skb, &data_start, &data_end, l4_hdr_off)) {
return TC_ACT_OK;
}

// IP headers
struct iphdr *iph = (struct iphdr *)(data_start + sizeof(struct ethhdr));
// filter out non-TCP packets
if (iph->protocol != IPPROTO_TCP) {
return TC_ACT_OK;
}
struct net_id_t conn_id = {0};
conn_id.protocol = iph->protocol;
conn_id.src_ip4 = iph->saddr;
conn_id.dst_ip4 = iph->daddr;
struct net_ctx_t *net_ctx = NULL;
if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
// IPv6 packect
uint32_t l6_hdr_off = sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
if (!skb_revalidate_data(skb, &data_start, &data_end, l6_hdr_off)) {
return TC_ACT_OK;
}

if (!skb_revalidate_data(skb, &data_start, &data_end,
l4_hdr_off + sizeof(struct tcphdr))) {
return TC_ACT_OK;
}
// debug_bpf_printk("!!!capture_packets src_ip4 : %d, dst_ip4 port :%d\n", conn_id.src_ip4, conn_id.dst_ip4);
struct tcphdr *tcp = (struct tcphdr *)(data_start + l4_hdr_off);
struct ipv6hdr *iph = (struct ipv6hdr *)(data_start + sizeof(struct ethhdr));
if (iph->nexthdr != IPPROTO_TCP) {
return TC_ACT_OK;
}
struct net_id_t conn_id = {0};
conn_id.protocol = iph->nexthdr;
__builtin_memcpy(conn_id.src_ip6, &iph->saddr, sizeof(iph->saddr));
__builtin_memcpy(conn_id.dst_ip6, &iph->daddr, sizeof(iph->daddr));

if (!skb_revalidate_data(skb, &data_start, &data_end,
l6_hdr_off + sizeof(struct tcphdr))) {
return TC_ACT_OK;
}
struct tcphdr *tcp = (struct tcphdr *)(data_start + l6_hdr_off);

#ifndef KERNEL_LESS_5_2
if (!filter_pcap_l2(skb, data_start, data_end))
return TC_ACT_OK;
#endif

conn_id.src_port = bpf_ntohs(tcp->source);
conn_id.dst_port = bpf_ntohs(tcp->dest);

net_ctx = bpf_map_lookup_elem(&network_map, &conn_id);
if (net_ctx == NULL) {
u32 tmp_ip[4];
__builtin_memcpy(tmp_ip, conn_id.src_ip6, sizeof(conn_id.src_ip6));
__builtin_memcpy(conn_id.src_ip6, conn_id.dst_ip6, sizeof(conn_id.dst_ip6));
__builtin_memcpy(conn_id.dst_ip6, tmp_ip, sizeof(tmp_ip));
u32 tmp_port = conn_id.src_port;
conn_id.src_port = conn_id.dst_port;
conn_id.dst_port = tmp_port;
net_ctx = bpf_map_lookup_elem(&network_map, &conn_id);
}
} else if (eth->h_proto == bpf_htons(ETH_P_IP)) {
// IPv4 packect
l4_hdr_off = sizeof(struct ethhdr) + sizeof(struct iphdr);
if (!skb_revalidate_data(skb, &data_start, &data_end, l4_hdr_off)) {
return TC_ACT_OK;
}
// IP headers
struct iphdr *iph = (struct iphdr *)(data_start + sizeof(struct ethhdr));
// filter out non-TCP packets
if (iph->protocol != IPPROTO_TCP) {
return TC_ACT_OK;
}
struct net_id_t conn_id = {0};
conn_id.protocol = iph->protocol;
conn_id.src_ip4 = iph->saddr;
conn_id.dst_ip4 = iph->daddr;
if (!skb_revalidate_data(skb, &data_start, &data_end,
l4_hdr_off + sizeof(struct tcphdr))) {
return TC_ACT_OK;
}
// debug_bpf_printk("!!!capture_packets src_ip4 : %d, dst_ip4 port :%d\n", conn_id.src_ip4, conn_id.dst_ip4);
struct tcphdr *tcp = (struct tcphdr *)(data_start + l4_hdr_off);

conn_id.src_port = bpf_ntohs(tcp->source);
conn_id.dst_port = bpf_ntohs(tcp->dest);
// debug_bpf_printk("!!!capture_packets port : %d, dest port :%d\n", conn_id.src_port, conn_id.dst_port);
#ifndef KERNEL_LESS_5_2
if (!filter_pcap_l2(skb, data_start, data_end))
return TC_ACT_OK;
#endif

struct net_ctx_t *net_ctx = bpf_map_lookup_elem(&network_map, &conn_id);
if (net_ctx == NULL) {
// exchange src and dst
u32 tmp_ip = conn_id.src_ip4;
conn_id.src_ip4 = conn_id.dst_ip4;
conn_id.dst_ip4 = tmp_ip;
u32 tmp_port = conn_id.src_port;
conn_id.src_port = conn_id.dst_port;
conn_id.dst_port = tmp_port;
conn_id.src_port = bpf_ntohs(tcp->source);
conn_id.dst_port = bpf_ntohs(tcp->dest);
// debug_bpf_printk("!!!capture_packets port : %d, dest port :%d\n", conn_id.src_port, conn_id.dst_port);
net_ctx = bpf_map_lookup_elem(&network_map, &conn_id);
if (net_ctx == NULL) {
// exchange src and dst
u32 tmp_ip = conn_id.src_ip4;
conn_id.src_ip4 = conn_id.dst_ip4;
conn_id.dst_ip4 = tmp_ip;
u32 tmp_port = conn_id.src_port;
conn_id.src_port = conn_id.dst_port;
conn_id.dst_port = tmp_port;
net_ctx = bpf_map_lookup_elem(&network_map, &conn_id);
}
}

// new packet event
Expand Down Expand Up @@ -260,23 +296,34 @@ int tcp_sendmsg(struct pt_regs *ctx){
}

u16 family, lport, dport;
u32 src_ip4, dst_ip4;
struct net_id_t conn_id = {0};
bpf_probe_read(&family, sizeof(family), &sk->__sk_common.skc_family);

if (family != AF_INET) {
return 0;
if (family == AF_INET6) {
u32 src_ip6[4], dst_ip6[4];
bpf_probe_read(&lport, sizeof(lport), &sk->__sk_common.skc_num);
bpf_probe_read(&dport, sizeof(dport), &sk->__sk_common.skc_dport);
bpf_probe_read(&src_ip6, sizeof(src_ip6), &sk->__sk_common.skc_v6_rcv_saddr);
bpf_probe_read(&dst_ip6, sizeof(dst_ip6), &sk->__sk_common.skc_v6_daddr);

conn_id.protocol = IPPROTO_TCP;
conn_id.src_port = lport;
conn_id.dst_port = bpf_ntohs(dport);
__builtin_memcpy(conn_id.src_ip6, src_ip6, sizeof(src_ip6));
__builtin_memcpy(conn_id.dst_ip6, dst_ip6, sizeof(dst_ip6));
} else if (family == AF_INET) {
u32 src_ip4, dst_ip4;
bpf_probe_read(&lport, sizeof(lport), &sk->__sk_common.skc_num);
bpf_probe_read(&dport, sizeof(dport), &sk->__sk_common.skc_dport);
bpf_probe_read(&src_ip4, sizeof(src_ip4), &sk->__sk_common.skc_rcv_saddr);
bpf_probe_read(&dst_ip4, sizeof(dst_ip4), &sk->__sk_common.skc_daddr);

conn_id.protocol = IPPROTO_TCP;
conn_id.src_port = lport;
conn_id.src_ip4 = src_ip4;
conn_id.dst_port = bpf_ntohs(dport);
conn_id.dst_ip4 = dst_ip4;
}
bpf_probe_read(&lport, sizeof(lport), &sk->__sk_common.skc_num);
bpf_probe_read(&dport, sizeof(dport), &sk->__sk_common.skc_dport);
bpf_probe_read(&src_ip4, sizeof(src_ip4), &sk->__sk_common.skc_rcv_saddr);
bpf_probe_read(&dst_ip4, sizeof(dst_ip4), &sk->__sk_common.skc_daddr);

struct net_id_t conn_id = {0};
conn_id.protocol = IPPROTO_TCP;
conn_id.src_port = lport;
conn_id.src_ip4 = src_ip4;
conn_id.dst_port = bpf_ntohs(dport);
conn_id.dst_ip4 = dst_ip4;

struct net_ctx_t net_ctx;
net_ctx.pid = pid;
Expand All @@ -285,4 +332,4 @@ int tcp_sendmsg(struct pt_regs *ctx){
debug_bpf_printk("tcp_sendmsg pid : %d, comm :%s\n", net_ctx.pid, net_ctx.comm);
bpf_map_update_elem(&network_map, &conn_id, &net_ctx, BPF_ANY);
return 0;
};
};
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