| #!/usr/bin/python |
| # @lint-avoid-python-3-compatibility-imports |
| # |
| # tcpconnect Trace TCP connect()s. |
| # For Linux, uses BCC, eBPF. Embedded C. |
| # |
| # USAGE: tcpconnect [-h] [-c] [-t] [-p PID] [-P PORT [PORT ...]] |
| # |
| # All connection attempts are traced, even if they ultimately fail. |
| # |
| # This uses dynamic tracing of kernel functions, and will need to be updated |
| # to match kernel changes. |
| # |
| # Copyright (c) 2015 Brendan Gregg. |
| # Licensed under the Apache License, Version 2.0 (the "License") |
| # |
| # 25-Sep-2015 Brendan Gregg Created this. |
| # 14-Feb-2016 " " Switch to bpf_perf_output. |
| # 09-Jan-2019 Takuma Kume Support filtering by UID |
| # 30-Jul-2019 Xiaozhou Liu Count connects. |
| # 07-Oct-2020 Nabil Schear Correlate connects with DNS responses |
| # 08-Mar-2021 Suresh Kumar Added LPORT option |
| |
| from __future__ import print_function |
| from bcc import BPF |
| from bcc.containers import filter_by_containers |
| from bcc.utils import printb |
| import argparse |
| from socket import inet_ntop, ntohs, AF_INET, AF_INET6 |
| from struct import pack |
| from time import sleep |
| from datetime import datetime |
| |
| # arguments |
| examples = """examples: |
| ./tcpconnect # trace all TCP connect()s |
| ./tcpconnect -t # include timestamps |
| ./tcpconnect -d # include DNS queries associated with connects |
| ./tcpconnect -p 181 # only trace PID 181 |
| ./tcpconnect -P 80 # only trace port 80 |
| ./tcpconnect -P 80,81 # only trace port 80 and 81 |
| ./tcpconnect -U # include UID |
| ./tcpconnect -u 1000 # only trace UID 1000 |
| ./tcpconnect -c # count connects per src ip and dest ip/port |
| ./tcpconnect -L # include LPORT while printing outputs |
| ./tcpconnect --cgroupmap mappath # only trace cgroups in this BPF map |
| ./tcpconnect --mntnsmap mappath # only trace mount namespaces in the map |
| """ |
| parser = argparse.ArgumentParser( |
| description="Trace TCP connects", |
| formatter_class=argparse.RawDescriptionHelpFormatter, |
| epilog=examples) |
| parser.add_argument("-t", "--timestamp", action="store_true", |
| help="include timestamp on output") |
| parser.add_argument("-p", "--pid", |
| help="trace this PID only") |
| parser.add_argument("-P", "--port", |
| help="comma-separated list of destination ports to trace.") |
| parser.add_argument("-L", "--lport", action="store_true", |
| help="include LPORT on output") |
| parser.add_argument("-U", "--print-uid", action="store_true", |
| help="include UID on output") |
| parser.add_argument("-u", "--uid", |
| help="trace this UID only") |
| parser.add_argument("-c", "--count", action="store_true", |
| help="count connects per src ip and dest ip/port") |
| parser.add_argument("--cgroupmap", |
| help="trace cgroups in this BPF map only") |
| parser.add_argument("--mntnsmap", |
| help="trace mount namespaces in this BPF map only") |
| parser.add_argument("-d", "--dns", action="store_true", |
| help="include likely DNS query associated with each connect") |
| parser.add_argument("--ebpf", action="store_true", |
| help=argparse.SUPPRESS) |
| args = parser.parse_args() |
| debug = 0 |
| |
| # define BPF program |
| bpf_text = """ |
| #include <uapi/linux/ptrace.h> |
| #include <net/sock.h> |
| #include <bcc/proto.h> |
| |
| BPF_HASH(currsock, u32, struct sock *); |
| |
| // separate data structs for ipv4 and ipv6 |
| struct ipv4_data_t { |
| u64 ts_us; |
| u32 pid; |
| u32 uid; |
| u32 saddr; |
| u32 daddr; |
| u64 ip; |
| u16 lport; |
| u16 dport; |
| char task[TASK_COMM_LEN]; |
| }; |
| BPF_PERF_OUTPUT(ipv4_events); |
| |
| struct ipv6_data_t { |
| u64 ts_us; |
| u32 pid; |
| u32 uid; |
| unsigned __int128 saddr; |
| unsigned __int128 daddr; |
| u64 ip; |
| u16 lport; |
| u16 dport; |
| char task[TASK_COMM_LEN]; |
| }; |
| BPF_PERF_OUTPUT(ipv6_events); |
| |
| // separate flow keys per address family |
| struct ipv4_flow_key_t { |
| u32 saddr; |
| u32 daddr; |
| u16 dport; |
| }; |
| BPF_HASH(ipv4_count, struct ipv4_flow_key_t); |
| |
| struct ipv6_flow_key_t { |
| unsigned __int128 saddr; |
| unsigned __int128 daddr; |
| u16 dport; |
| }; |
| BPF_HASH(ipv6_count, struct ipv6_flow_key_t); |
| |
| int trace_connect_entry(struct pt_regs *ctx, struct sock *sk) |
| { |
| if (container_should_be_filtered()) { |
| return 0; |
| } |
| |
| u64 pid_tgid = bpf_get_current_pid_tgid(); |
| u32 pid = pid_tgid >> 32; |
| u32 tid = pid_tgid; |
| FILTER_PID |
| |
| u32 uid = bpf_get_current_uid_gid(); |
| FILTER_UID |
| |
| // stash the sock ptr for lookup on return |
| currsock.update(&tid, &sk); |
| |
| return 0; |
| }; |
| |
| static int trace_connect_return(struct pt_regs *ctx, short ipver) |
| { |
| int ret = PT_REGS_RC(ctx); |
| u64 pid_tgid = bpf_get_current_pid_tgid(); |
| u32 pid = pid_tgid >> 32; |
| u32 tid = pid_tgid; |
| |
| struct sock **skpp; |
| skpp = currsock.lookup(&tid); |
| if (skpp == 0) { |
| return 0; // missed entry |
| } |
| |
| if (ret != 0) { |
| // failed to send SYNC packet, may not have populated |
| // socket __sk_common.{skc_rcv_saddr, ...} |
| currsock.delete(&tid); |
| return 0; |
| } |
| |
| // pull in details |
| struct sock *skp = *skpp; |
| u16 lport = skp->__sk_common.skc_num; |
| u16 dport = skp->__sk_common.skc_dport; |
| |
| FILTER_PORT |
| |
| if (ipver == 4) { |
| IPV4_CODE |
| } else /* 6 */ { |
| IPV6_CODE |
| } |
| |
| currsock.delete(&tid); |
| |
| return 0; |
| } |
| |
| int trace_connect_v4_return(struct pt_regs *ctx) |
| { |
| return trace_connect_return(ctx, 4); |
| } |
| |
| int trace_connect_v6_return(struct pt_regs *ctx) |
| { |
| return trace_connect_return(ctx, 6); |
| } |
| """ |
| |
| struct_init = {'ipv4': |
| {'count': |
| """ |
| struct ipv4_flow_key_t flow_key = {}; |
| flow_key.saddr = skp->__sk_common.skc_rcv_saddr; |
| flow_key.daddr = skp->__sk_common.skc_daddr; |
| flow_key.dport = ntohs(dport); |
| ipv4_count.increment(flow_key);""", |
| 'trace': |
| """ |
| struct ipv4_data_t data4 = {.pid = pid, .ip = ipver}; |
| data4.uid = bpf_get_current_uid_gid(); |
| data4.ts_us = bpf_ktime_get_ns() / 1000; |
| data4.saddr = skp->__sk_common.skc_rcv_saddr; |
| data4.daddr = skp->__sk_common.skc_daddr; |
| data4.lport = lport; |
| data4.dport = ntohs(dport); |
| bpf_get_current_comm(&data4.task, sizeof(data4.task)); |
| ipv4_events.perf_submit(ctx, &data4, sizeof(data4));""" |
| }, |
| 'ipv6': |
| {'count': |
| """ |
| struct ipv6_flow_key_t flow_key = {}; |
| bpf_probe_read_kernel(&flow_key.saddr, sizeof(flow_key.saddr), |
| skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32); |
| bpf_probe_read_kernel(&flow_key.daddr, sizeof(flow_key.daddr), |
| skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32); |
| flow_key.dport = ntohs(dport); |
| ipv6_count.increment(flow_key);""", |
| 'trace': |
| """ |
| struct ipv6_data_t data6 = {.pid = pid, .ip = ipver}; |
| data6.uid = bpf_get_current_uid_gid(); |
| data6.ts_us = bpf_ktime_get_ns() / 1000; |
| bpf_probe_read_kernel(&data6.saddr, sizeof(data6.saddr), |
| skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32); |
| bpf_probe_read_kernel(&data6.daddr, sizeof(data6.daddr), |
| skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32); |
| data6.lport = lport; |
| data6.dport = ntohs(dport); |
| bpf_get_current_comm(&data6.task, sizeof(data6.task)); |
| ipv6_events.perf_submit(ctx, &data6, sizeof(data6));""" |
| } |
| } |
| |
| # This defines an additional BPF program that instruments udp_recvmsg system |
| # call to locate DNS response packets on UDP port 53. When these packets are |
| # located, the data is copied to user-space where python will parse them with |
| # dnslib. |
| # |
| # uses a percpu array of length 1 to store the dns_data_t off the stack to |
| # allow for a maximum DNS packet length of 512 bytes. |
| dns_bpf_text = """ |
| #include <net/inet_sock.h> |
| |
| #define MAX_PKT 512 |
| struct dns_data_t { |
| u8 pkt[MAX_PKT]; |
| }; |
| |
| BPF_PERF_OUTPUT(dns_events); |
| |
| // store msghdr pointer captured on syscall entry to parse on syscall return |
| BPF_HASH(tbl_udp_msg_hdr, u64, struct msghdr *); |
| |
| // single element per-cpu array to hold the current event off the stack |
| BPF_PERCPU_ARRAY(dns_data,struct dns_data_t,1); |
| |
| int trace_udp_recvmsg(struct pt_regs *ctx) |
| { |
| __u64 pid_tgid = bpf_get_current_pid_tgid(); |
| struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx); |
| struct inet_sock *is = inet_sk(sk); |
| |
| // only grab port 53 packets, 13568 is ntohs(53) |
| if (is->inet_dport == 13568) { |
| struct msghdr *msghdr = (struct msghdr *)PT_REGS_PARM2(ctx); |
| tbl_udp_msg_hdr.update(&pid_tgid, &msghdr); |
| } |
| return 0; |
| } |
| |
| int trace_udp_ret_recvmsg(struct pt_regs *ctx) |
| { |
| __u64 pid_tgid = bpf_get_current_pid_tgid(); |
| u32 zero = 0; |
| struct msghdr **msgpp = tbl_udp_msg_hdr.lookup(&pid_tgid); |
| if (msgpp == 0) |
| return 0; |
| |
| struct msghdr *msghdr = (struct msghdr *)*msgpp; |
| if (msghdr->msg_iter.type != ITER_IOVEC) |
| goto delete_and_return; |
| |
| int copied = (int)PT_REGS_RC(ctx); |
| if (copied < 0) |
| goto delete_and_return; |
| size_t buflen = (size_t)copied; |
| |
| if (buflen > msghdr->msg_iter.iov->iov_len) |
| goto delete_and_return; |
| |
| if (buflen > MAX_PKT) |
| buflen = MAX_PKT; |
| |
| struct dns_data_t *data = dns_data.lookup(&zero); |
| if (!data) // this should never happen, just making the verifier happy |
| return 0; |
| |
| void *iovbase = msghdr->msg_iter.iov->iov_base; |
| bpf_probe_read(data->pkt, buflen, iovbase); |
| dns_events.perf_submit(ctx, data, buflen); |
| |
| delete_and_return: |
| tbl_udp_msg_hdr.delete(&pid_tgid); |
| return 0; |
| } |
| |
| """ |
| |
| if args.count and args.dns: |
| print("Error: you may not specify -d/--dns with -c/--count.") |
| exit() |
| |
| # code substitutions |
| if args.count: |
| bpf_text = bpf_text.replace("IPV4_CODE", struct_init['ipv4']['count']) |
| bpf_text = bpf_text.replace("IPV6_CODE", struct_init['ipv6']['count']) |
| else: |
| bpf_text = bpf_text.replace("IPV4_CODE", struct_init['ipv4']['trace']) |
| bpf_text = bpf_text.replace("IPV6_CODE", struct_init['ipv6']['trace']) |
| |
| if args.pid: |
| bpf_text = bpf_text.replace('FILTER_PID', |
| 'if (pid != %s) { return 0; }' % args.pid) |
| if args.port: |
| dports = [int(dport) for dport in args.port.split(',')] |
| dports_if = ' && '.join(['dport != %d' % ntohs(dport) for dport in dports]) |
| bpf_text = bpf_text.replace('FILTER_PORT', |
| 'if (%s) { currsock.delete(&tid); return 0; }' % dports_if) |
| if args.uid: |
| bpf_text = bpf_text.replace('FILTER_UID', |
| 'if (uid != %s) { return 0; }' % args.uid) |
| bpf_text = filter_by_containers(args) + bpf_text |
| |
| bpf_text = bpf_text.replace('FILTER_PID', '') |
| bpf_text = bpf_text.replace('FILTER_PORT', '') |
| bpf_text = bpf_text.replace('FILTER_UID', '') |
| |
| if args.dns: |
| bpf_text += dns_bpf_text |
| |
| if debug or args.ebpf: |
| print(bpf_text) |
| if args.ebpf: |
| exit() |
| |
| # process event |
| def print_ipv4_event(cpu, data, size): |
| event = b["ipv4_events"].event(data) |
| global start_ts |
| if args.timestamp: |
| if start_ts == 0: |
| start_ts = event.ts_us |
| printb(b"%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), nl="") |
| if args.print_uid: |
| printb(b"%-6d" % event.uid, nl="") |
| dest_ip = inet_ntop(AF_INET, pack("I", event.daddr)).encode() |
| if args.lport: |
| printb(b"%-6d %-12.12s %-2d %-16s %-6d %-16s %-6d %s" % (event.pid, |
| event.task, event.ip, |
| inet_ntop(AF_INET, pack("I", event.saddr)).encode(), event.lport, |
| dest_ip, event.dport, print_dns(dest_ip))) |
| else: |
| printb(b"%-6d %-12.12s %-2d %-16s %-16s %-6d %s" % (event.pid, |
| event.task, event.ip, |
| inet_ntop(AF_INET, pack("I", event.saddr)).encode(), |
| dest_ip, event.dport, print_dns(dest_ip))) |
| |
| def print_ipv6_event(cpu, data, size): |
| event = b["ipv6_events"].event(data) |
| global start_ts |
| if args.timestamp: |
| if start_ts == 0: |
| start_ts = event.ts_us |
| printb(b"%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), nl="") |
| if args.print_uid: |
| printb(b"%-6d" % event.uid, nl="") |
| dest_ip = inet_ntop(AF_INET6, event.daddr).encode() |
| if args.lport: |
| printb(b"%-6d %-12.12s %-2d %-16s %-6d %-16s %-6d %s" % (event.pid, |
| event.task, event.ip, |
| inet_ntop(AF_INET6, event.saddr).encode(), event.lport, |
| dest_ip, event.dport, print_dns(dest_ip))) |
| else: |
| printb(b"%-6d %-12.12s %-2d %-16s %-16s %-6d %s" % (event.pid, |
| event.task, event.ip, |
| inet_ntop(AF_INET6, event.saddr).encode(), |
| dest_ip, event.dport, print_dns(dest_ip))) |
| |
| def depict_cnt(counts_tab, l3prot='ipv4'): |
| for k, v in sorted(counts_tab.items(), |
| key=lambda counts: counts[1].value, reverse=True): |
| depict_key = "" |
| if l3prot == 'ipv4': |
| depict_key = "%-25s %-25s %-20s" % \ |
| ((inet_ntop(AF_INET, pack('I', k.saddr))), |
| inet_ntop(AF_INET, pack('I', k.daddr)), k.dport) |
| else: |
| depict_key = "%-25s %-25s %-20s" % \ |
| ((inet_ntop(AF_INET6, k.saddr)), |
| inet_ntop(AF_INET6, k.daddr), k.dport) |
| |
| print("%s %-10d" % (depict_key, v.value)) |
| |
| def print_dns(dest_ip): |
| if not args.dns: |
| return b"" |
| |
| dnsname, timestamp = dns_cache.get(dest_ip, (None, None)) |
| if timestamp is not None: |
| diff = datetime.now() - timestamp |
| diff = float(diff.seconds) * 1000 + float(diff.microseconds) / 1000 |
| else: |
| diff = 0 |
| if dnsname is None: |
| dnsname = b"No DNS Query" |
| if dest_ip == b"127.0.0.1" or dest_ip == b"::1": |
| dnsname = b"localhost" |
| retval = b"%s" % dnsname |
| if diff > DELAY_DNS: |
| retval += b" (%.3fms)" % diff |
| return retval |
| |
| if args.dns: |
| try: |
| import dnslib |
| from cachetools import TTLCache |
| except ImportError: |
| print("Error: The python packages dnslib and cachetools are required " |
| "to use the -d/--dns option.") |
| print("Install this package with:") |
| print("\t$ pip3 install dnslib cachetools") |
| print(" or") |
| print("\t$ sudo apt-get install python3-dnslib python3-cachetools " |
| "(on Ubuntu 18.04+)") |
| exit(1) |
| |
| # 24 hours |
| DEFAULT_TTL = 86400 |
| |
| # Cache Size in entries |
| DNS_CACHE_SIZE = 10240 |
| |
| # delay in ms in which to warn users of long delay between the query |
| # and the connect that used the IP |
| DELAY_DNS = 100 |
| |
| dns_cache = TTLCache(maxsize=DNS_CACHE_SIZE, ttl=DEFAULT_TTL) |
| |
| # process event |
| def save_dns(cpu, data, size): |
| event = b["dns_events"].event(data) |
| payload = event.pkt[:size] |
| |
| # pass the payload to dnslib for parsing |
| dnspkt = dnslib.DNSRecord.parse(payload) |
| # lets only look at responses |
| if dnspkt.header.qr != 1: |
| return |
| # must be some questions in there |
| if dnspkt.header.q != 1: |
| return |
| # make sure there are answers |
| if dnspkt.header.a == 0 and dnspkt.header.aa == 0: |
| return |
| |
| # lop off the trailing . |
| question = ("%s" % dnspkt.q.qname)[:-1].encode('utf-8') |
| |
| for answer in dnspkt.rr: |
| # skip all but A and AAAA records |
| if answer.rtype == 1 or answer.rtype == 28: |
| dns_cache[str(answer.rdata).encode('utf-8')] = (question, |
| datetime.now()) |
| |
| # initialize BPF |
| b = BPF(text=bpf_text) |
| b.attach_kprobe(event="tcp_v4_connect", fn_name="trace_connect_entry") |
| b.attach_kprobe(event="tcp_v6_connect", fn_name="trace_connect_entry") |
| b.attach_kretprobe(event="tcp_v4_connect", fn_name="trace_connect_v4_return") |
| b.attach_kretprobe(event="tcp_v6_connect", fn_name="trace_connect_v6_return") |
| if args.dns: |
| b.attach_kprobe(event="udp_recvmsg", fn_name="trace_udp_recvmsg") |
| b.attach_kretprobe(event="udp_recvmsg", fn_name="trace_udp_ret_recvmsg") |
| |
| print("Tracing connect ... Hit Ctrl-C to end") |
| if args.count: |
| try: |
| while True: |
| sleep(99999999) |
| except KeyboardInterrupt: |
| pass |
| |
| # header |
| print("\n%-25s %-25s %-20s %-10s" % ( |
| "LADDR", "RADDR", "RPORT", "CONNECTS")) |
| depict_cnt(b["ipv4_count"]) |
| depict_cnt(b["ipv6_count"], l3prot='ipv6') |
| # read events |
| else: |
| # header |
| if args.timestamp: |
| print("%-9s" % ("TIME(s)"), end="") |
| if args.print_uid: |
| print("%-6s" % ("UID"), end="") |
| if args.lport: |
| print("%-6s %-12s %-2s %-16s %-6s %-16s %-6s" % ("PID", "COMM", "IP", "SADDR", |
| "LPORT", "DADDR", "DPORT"), end="") |
| else: |
| print("%-6s %-12s %-2s %-16s %-16s %-6s" % ("PID", "COMM", "IP", "SADDR", |
| "DADDR", "DPORT"), end="") |
| if args.dns: |
| print(" QUERY") |
| else: |
| print() |
| |
| start_ts = 0 |
| |
| # read events |
| b["ipv4_events"].open_perf_buffer(print_ipv4_event) |
| b["ipv6_events"].open_perf_buffer(print_ipv6_event) |
| if args.dns: |
| b["dns_events"].open_perf_buffer(save_dns) |
| while True: |
| try: |
| b.perf_buffer_poll() |
| except KeyboardInterrupt: |
| exit() |
