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#! /usr/bin/python3 # @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 ...]] [-4 | -6] # # 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 -4 # only trace IPv4 family ./tcpconnect -6 # only trace IPv6 family ./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.") group = parser.add_mutually_exclusive_group() group.add_argument("-4", "--ipv4", action="store_true", help="trace IPv4 family only") group.add_argument("-6", "--ipv6", action="store_true", help="trace IPv6 family only") 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 FILTER_FAMILY 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_FIELD != 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; } #include <uapi/linux/udp.h> int trace_udpv6_recvmsg(struct pt_regs *ctx) { struct sk_buff *skb = (struct sk_buff *)PT_REGS_PARM2(ctx); struct udphdr *hdr = (void*)skb->head + skb->transport_header; struct dns_data_t *event; int zero = 0; void *data; /* hex(53) = 0x0035, htons(0x0035) = 0x3500 */ if (hdr->source != 0x3500) return 0; /* skip UDP header */ data = skb->data + 8; event = dns_data.lookup(&zero); if (!event) return 0; bpf_probe_read(event->pkt, sizeof(event->pkt), data); dns_events.perf_submit(ctx, event, sizeof(*event)); 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.ipv4: bpf_text = bpf_text.replace('FILTER_FAMILY', 'if (ipver != 4) { return 0; }') elif args.ipv6: bpf_text = bpf_text.replace('FILTER_FAMILY', 'if (ipver != 6) { return 0; }') 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_FAMILY', '') bpf_text = bpf_text.replace('FILTER_UID', '') if args.dns: if BPF.kernel_struct_has_field(b'iov_iter', b'iter_type') == 1: dns_bpf_text = dns_bpf_text.replace('TYPE_FIELD', 'iter_type') else: dns_bpf_text = dns_bpf_text.replace('TYPE_FIELD', 'type') 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"%-7d %-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"%-7d %-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"%-7d %-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"%-7d %-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") b.attach_kprobe(event="udpv6_queue_rcv_one_skb", fn_name="trace_udpv6_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("%-7s %-12s %-2s %-16s %-6s %-16s %-6s" % ("PID", "COMM", "IP", "SADDR", "LPORT", "DADDR", "DPORT"), end="") else: print("%-7s %-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()