557 lines
18 KiB
Python
Executable File
557 lines
18 KiB
Python
Executable File
#!/usr/bin/python
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# @lint-avoid-python-3-compatibility-imports
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#
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# tcpconnect Trace TCP connect()s.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: tcpconnect [-h] [-c] [-t] [-p PID] [-P PORT [PORT ...]] [-4 | -6]
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#
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# All connection attempts are traced, even if they ultimately fail.
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#
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# This uses dynamic tracing of kernel functions, and will need to be updated
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# to match kernel changes.
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#
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# Copyright (c) 2015 Brendan Gregg.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 25-Sep-2015 Brendan Gregg Created this.
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# 14-Feb-2016 " " Switch to bpf_perf_output.
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# 09-Jan-2019 Takuma Kume Support filtering by UID
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# 30-Jul-2019 Xiaozhou Liu Count connects.
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# 07-Oct-2020 Nabil Schear Correlate connects with DNS responses
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# 08-Mar-2021 Suresh Kumar Added LPORT option
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from __future__ import print_function
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from bcc import BPF
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from bcc.containers import filter_by_containers
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from bcc.utils import printb
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import argparse
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from socket import inet_ntop, ntohs, AF_INET, AF_INET6
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from struct import pack
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from time import sleep
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from datetime import datetime
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# arguments
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examples = """examples:
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./tcpconnect # trace all TCP connect()s
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./tcpconnect -t # include timestamps
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./tcpconnect -d # include DNS queries associated with connects
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./tcpconnect -p 181 # only trace PID 181
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./tcpconnect -P 80 # only trace port 80
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./tcpconnect -P 80,81 # only trace port 80 and 81
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./tcpconnect -4 # only trace IPv4 family
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./tcpconnect -6 # only trace IPv6 family
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./tcpconnect -U # include UID
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./tcpconnect -u 1000 # only trace UID 1000
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./tcpconnect -c # count connects per src ip and dest ip/port
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./tcpconnect -L # include LPORT while printing outputs
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./tcpconnect --cgroupmap mappath # only trace cgroups in this BPF map
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./tcpconnect --mntnsmap mappath # only trace mount namespaces in the map
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"""
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parser = argparse.ArgumentParser(
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description="Trace TCP connects",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog=examples)
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parser.add_argument("-t", "--timestamp", action="store_true",
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help="include timestamp on output")
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parser.add_argument("-p", "--pid",
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help="trace this PID only")
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parser.add_argument("-P", "--port",
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help="comma-separated list of destination ports to trace.")
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group = parser.add_mutually_exclusive_group()
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group.add_argument("-4", "--ipv4", action="store_true",
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help="trace IPv4 family only")
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group.add_argument("-6", "--ipv6", action="store_true",
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help="trace IPv6 family only")
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parser.add_argument("-L", "--lport", action="store_true",
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help="include LPORT on output")
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parser.add_argument("-U", "--print-uid", action="store_true",
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help="include UID on output")
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parser.add_argument("-u", "--uid",
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help="trace this UID only")
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parser.add_argument("-c", "--count", action="store_true",
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help="count connects per src ip and dest ip/port")
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parser.add_argument("--cgroupmap",
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help="trace cgroups in this BPF map only")
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parser.add_argument("--mntnsmap",
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help="trace mount namespaces in this BPF map only")
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parser.add_argument("-d", "--dns", action="store_true",
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help="include likely DNS query associated with each connect")
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parser.add_argument("--ebpf", action="store_true",
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help=argparse.SUPPRESS)
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args = parser.parse_args()
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debug = 0
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# define BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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#include <net/sock.h>
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#include <bcc/proto.h>
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BPF_HASH(currsock, u32, struct sock *);
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// separate data structs for ipv4 and ipv6
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struct ipv4_data_t {
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u64 ts_us;
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u32 pid;
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u32 uid;
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u32 saddr;
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u32 daddr;
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u64 ip;
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u16 lport;
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u16 dport;
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char task[TASK_COMM_LEN];
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};
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BPF_PERF_OUTPUT(ipv4_events);
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struct ipv6_data_t {
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u64 ts_us;
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u32 pid;
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u32 uid;
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unsigned __int128 saddr;
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unsigned __int128 daddr;
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u64 ip;
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u16 lport;
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u16 dport;
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char task[TASK_COMM_LEN];
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};
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BPF_PERF_OUTPUT(ipv6_events);
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// separate flow keys per address family
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struct ipv4_flow_key_t {
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u32 saddr;
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u32 daddr;
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u16 dport;
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};
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BPF_HASH(ipv4_count, struct ipv4_flow_key_t);
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struct ipv6_flow_key_t {
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unsigned __int128 saddr;
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unsigned __int128 daddr;
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u16 dport;
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};
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BPF_HASH(ipv6_count, struct ipv6_flow_key_t);
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int trace_connect_entry(struct pt_regs *ctx, struct sock *sk)
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{
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if (container_should_be_filtered()) {
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return 0;
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}
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u64 pid_tgid = bpf_get_current_pid_tgid();
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u32 pid = pid_tgid >> 32;
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u32 tid = pid_tgid;
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FILTER_PID
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u32 uid = bpf_get_current_uid_gid();
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FILTER_UID
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// stash the sock ptr for lookup on return
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currsock.update(&tid, &sk);
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return 0;
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};
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static int trace_connect_return(struct pt_regs *ctx, short ipver)
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{
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int ret = PT_REGS_RC(ctx);
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u64 pid_tgid = bpf_get_current_pid_tgid();
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u32 pid = pid_tgid >> 32;
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u32 tid = pid_tgid;
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struct sock **skpp;
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skpp = currsock.lookup(&tid);
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if (skpp == 0) {
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return 0; // missed entry
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}
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if (ret != 0) {
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// failed to send SYNC packet, may not have populated
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// socket __sk_common.{skc_rcv_saddr, ...}
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currsock.delete(&tid);
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return 0;
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}
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// pull in details
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struct sock *skp = *skpp;
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u16 lport = skp->__sk_common.skc_num;
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u16 dport = skp->__sk_common.skc_dport;
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FILTER_PORT
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FILTER_FAMILY
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if (ipver == 4) {
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IPV4_CODE
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} else /* 6 */ {
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IPV6_CODE
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}
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currsock.delete(&tid);
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return 0;
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}
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int trace_connect_v4_return(struct pt_regs *ctx)
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{
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return trace_connect_return(ctx, 4);
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}
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int trace_connect_v6_return(struct pt_regs *ctx)
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{
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return trace_connect_return(ctx, 6);
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}
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"""
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struct_init = {'ipv4':
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{'count':
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"""
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struct ipv4_flow_key_t flow_key = {};
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flow_key.saddr = skp->__sk_common.skc_rcv_saddr;
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flow_key.daddr = skp->__sk_common.skc_daddr;
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flow_key.dport = ntohs(dport);
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ipv4_count.increment(flow_key);""",
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'trace':
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"""
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struct ipv4_data_t data4 = {.pid = pid, .ip = ipver};
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data4.uid = bpf_get_current_uid_gid();
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data4.ts_us = bpf_ktime_get_ns() / 1000;
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data4.saddr = skp->__sk_common.skc_rcv_saddr;
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data4.daddr = skp->__sk_common.skc_daddr;
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data4.lport = lport;
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data4.dport = ntohs(dport);
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bpf_get_current_comm(&data4.task, sizeof(data4.task));
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ipv4_events.perf_submit(ctx, &data4, sizeof(data4));"""
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},
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'ipv6':
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{'count':
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"""
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struct ipv6_flow_key_t flow_key = {};
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bpf_probe_read_kernel(&flow_key.saddr, sizeof(flow_key.saddr),
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skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
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bpf_probe_read_kernel(&flow_key.daddr, sizeof(flow_key.daddr),
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skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
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flow_key.dport = ntohs(dport);
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ipv6_count.increment(flow_key);""",
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'trace':
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"""
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struct ipv6_data_t data6 = {.pid = pid, .ip = ipver};
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data6.uid = bpf_get_current_uid_gid();
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data6.ts_us = bpf_ktime_get_ns() / 1000;
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bpf_probe_read_kernel(&data6.saddr, sizeof(data6.saddr),
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skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
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bpf_probe_read_kernel(&data6.daddr, sizeof(data6.daddr),
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skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
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data6.lport = lport;
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data6.dport = ntohs(dport);
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bpf_get_current_comm(&data6.task, sizeof(data6.task));
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ipv6_events.perf_submit(ctx, &data6, sizeof(data6));"""
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}
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}
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# This defines an additional BPF program that instruments udp_recvmsg system
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# call to locate DNS response packets on UDP port 53. When these packets are
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# located, the data is copied to user-space where python will parse them with
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# dnslib.
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#
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# uses a percpu array of length 1 to store the dns_data_t off the stack to
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# allow for a maximum DNS packet length of 512 bytes.
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dns_bpf_text = """
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#include <net/inet_sock.h>
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#define MAX_PKT 512
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struct dns_data_t {
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u8 pkt[MAX_PKT];
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};
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BPF_PERF_OUTPUT(dns_events);
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// store msghdr pointer captured on syscall entry to parse on syscall return
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BPF_HASH(tbl_udp_msg_hdr, u64, struct msghdr *);
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// single element per-cpu array to hold the current event off the stack
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BPF_PERCPU_ARRAY(dns_data,struct dns_data_t,1);
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int trace_udp_recvmsg(struct pt_regs *ctx)
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{
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__u64 pid_tgid = bpf_get_current_pid_tgid();
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struct sock *sk = (struct sock *)PT_REGS_PARM1(ctx);
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struct inet_sock *is = inet_sk(sk);
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// only grab port 53 packets, 13568 is ntohs(53)
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if (is->inet_dport == 13568) {
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struct msghdr *msghdr = (struct msghdr *)PT_REGS_PARM2(ctx);
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tbl_udp_msg_hdr.update(&pid_tgid, &msghdr);
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}
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return 0;
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}
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int trace_udp_ret_recvmsg(struct pt_regs *ctx)
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{
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__u64 pid_tgid = bpf_get_current_pid_tgid();
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u32 zero = 0;
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struct msghdr **msgpp = tbl_udp_msg_hdr.lookup(&pid_tgid);
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if (msgpp == 0)
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return 0;
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struct msghdr *msghdr = (struct msghdr *)*msgpp;
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if (msghdr->msg_iter.TYPE_FIELD != ITER_IOVEC)
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goto delete_and_return;
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int copied = (int)PT_REGS_RC(ctx);
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if (copied < 0)
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goto delete_and_return;
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size_t buflen = (size_t)copied;
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if (buflen > msghdr->msg_iter.iov->iov_len)
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goto delete_and_return;
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if (buflen > MAX_PKT)
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buflen = MAX_PKT;
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struct dns_data_t *data = dns_data.lookup(&zero);
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if (!data) // this should never happen, just making the verifier happy
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return 0;
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void *iovbase = msghdr->msg_iter.iov->iov_base;
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bpf_probe_read(data->pkt, buflen, iovbase);
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dns_events.perf_submit(ctx, data, buflen);
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delete_and_return:
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tbl_udp_msg_hdr.delete(&pid_tgid);
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return 0;
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}
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"""
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if args.count and args.dns:
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print("Error: you may not specify -d/--dns with -c/--count.")
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exit()
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# code substitutions
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if args.count:
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bpf_text = bpf_text.replace("IPV4_CODE", struct_init['ipv4']['count'])
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bpf_text = bpf_text.replace("IPV6_CODE", struct_init['ipv6']['count'])
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else:
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bpf_text = bpf_text.replace("IPV4_CODE", struct_init['ipv4']['trace'])
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bpf_text = bpf_text.replace("IPV6_CODE", struct_init['ipv6']['trace'])
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if args.pid:
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bpf_text = bpf_text.replace('FILTER_PID',
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'if (pid != %s) { return 0; }' % args.pid)
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if args.port:
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dports = [int(dport) for dport in args.port.split(',')]
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dports_if = ' && '.join(['dport != %d' % ntohs(dport) for dport in dports])
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bpf_text = bpf_text.replace('FILTER_PORT',
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'if (%s) { currsock.delete(&tid); return 0; }' % dports_if)
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if args.ipv4:
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bpf_text = bpf_text.replace('FILTER_FAMILY',
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'if (ipver != 4) { return 0; }')
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elif args.ipv6:
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bpf_text = bpf_text.replace('FILTER_FAMILY',
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'if (ipver != 6) { return 0; }')
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if args.uid:
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bpf_text = bpf_text.replace('FILTER_UID',
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'if (uid != %s) { return 0; }' % args.uid)
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bpf_text = filter_by_containers(args) + bpf_text
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bpf_text = bpf_text.replace('FILTER_PID', '')
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bpf_text = bpf_text.replace('FILTER_PORT', '')
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bpf_text = bpf_text.replace('FILTER_FAMILY', '')
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bpf_text = bpf_text.replace('FILTER_UID', '')
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if args.dns:
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if BPF.kernel_struct_has_field(b'iov_iter', b'iter_type') == 1:
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dns_bpf_text = dns_bpf_text.replace('TYPE_FIELD', 'iter_type')
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else:
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dns_bpf_text = dns_bpf_text.replace('TYPE_FIELD', 'type')
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bpf_text += dns_bpf_text
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if debug or args.ebpf:
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print(bpf_text)
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if args.ebpf:
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exit()
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# process event
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def print_ipv4_event(cpu, data, size):
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event = b["ipv4_events"].event(data)
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global start_ts
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if args.timestamp:
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if start_ts == 0:
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start_ts = event.ts_us
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printb(b"%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), nl="")
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if args.print_uid:
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printb(b"%-6d" % event.uid, nl="")
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dest_ip = inet_ntop(AF_INET, pack("I", event.daddr)).encode()
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if args.lport:
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printb(b"%-7d %-12.12s %-2d %-16s %-6d %-16s %-6d %s" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET, pack("I", event.saddr)).encode(), event.lport,
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dest_ip, event.dport, print_dns(dest_ip)))
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else:
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printb(b"%-7d %-12.12s %-2d %-16s %-16s %-6d %s" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET, pack("I", event.saddr)).encode(),
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dest_ip, event.dport, print_dns(dest_ip)))
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def print_ipv6_event(cpu, data, size):
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event = b["ipv6_events"].event(data)
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global start_ts
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if args.timestamp:
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if start_ts == 0:
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start_ts = event.ts_us
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printb(b"%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), nl="")
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if args.print_uid:
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printb(b"%-6d" % event.uid, nl="")
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dest_ip = inet_ntop(AF_INET6, event.daddr).encode()
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if args.lport:
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printb(b"%-7d %-12.12s %-2d %-16s %-6d %-16s %-6d %s" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET6, event.saddr).encode(), event.lport,
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dest_ip, event.dport, print_dns(dest_ip)))
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else:
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printb(b"%-7d %-12.12s %-2d %-16s %-16s %-6d %s" % (event.pid,
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event.task, event.ip,
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inet_ntop(AF_INET6, event.saddr).encode(),
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dest_ip, event.dport, print_dns(dest_ip)))
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def depict_cnt(counts_tab, l3prot='ipv4'):
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for k, v in sorted(counts_tab.items(),
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key=lambda counts: counts[1].value, reverse=True):
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depict_key = ""
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if l3prot == 'ipv4':
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depict_key = "%-25s %-25s %-20s" % \
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((inet_ntop(AF_INET, pack('I', k.saddr))),
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inet_ntop(AF_INET, pack('I', k.daddr)), k.dport)
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else:
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depict_key = "%-25s %-25s %-20s" % \
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((inet_ntop(AF_INET6, k.saddr)),
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inet_ntop(AF_INET6, k.daddr), k.dport)
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print("%s %-10d" % (depict_key, v.value))
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def print_dns(dest_ip):
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if not args.dns:
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return b""
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dnsname, timestamp = dns_cache.get(dest_ip, (None, None))
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if timestamp is not None:
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diff = datetime.now() - timestamp
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diff = float(diff.seconds) * 1000 + float(diff.microseconds) / 1000
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else:
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diff = 0
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if dnsname is None:
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dnsname = b"No DNS Query"
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if dest_ip == b"127.0.0.1" or dest_ip == b"::1":
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dnsname = b"localhost"
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retval = b"%s" % dnsname
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if diff > DELAY_DNS:
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retval += b" (%.3fms)" % diff
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return retval
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|
|
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("%-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()
|