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1#!/usr/bin/python
2# @lint-avoid-python-3-compatibility-imports
3#
4# tcpconnect    Trace TCP connect()s.
5#               For Linux, uses BCC, eBPF. Embedded C.
6#
7# USAGE: tcpconnect [-h] [-t] [-p PID] [-P PORT [PORT ...]]
8#
9# All connection attempts are traced, even if they ultimately fail.
10#
11# This uses dynamic tracing of kernel functions, and will need to be updated
12# to match kernel changes.
13#
14# Copyright (c) 2015 Brendan Gregg.
15# Licensed under the Apache License, Version 2.0 (the "License")
16#
17# 25-Sep-2015   Brendan Gregg   Created this.
18# 14-Feb-2016      "      "     Switch to bpf_perf_output.
19
20from __future__ import print_function
21from bcc import BPF
22import argparse
23from socket import inet_ntop, ntohs, AF_INET, AF_INET6
24from struct import pack
25import ctypes as ct
26
27# arguments
28examples = """examples:
29    ./tcpconnect           # trace all TCP connect()s
30    ./tcpconnect -t        # include timestamps
31    ./tcpconnect -p 181    # only trace PID 181
32    ./tcpconnect -P 80     # only trace port 80
33    ./tcpconnect -P 80,81  # only trace port 80 and 81
34"""
35parser = argparse.ArgumentParser(
36    description="Trace TCP connects",
37    formatter_class=argparse.RawDescriptionHelpFormatter,
38    epilog=examples)
39parser.add_argument("-t", "--timestamp", action="store_true",
40    help="include timestamp on output")
41parser.add_argument("-p", "--pid",
42    help="trace this PID only")
43parser.add_argument("-P", "--port",
44    help="comma-separated list of destination ports to trace.")
45parser.add_argument("--ebpf", action="store_true",
46    help=argparse.SUPPRESS)
47args = parser.parse_args()
48debug = 0
49
50# define BPF program
51bpf_text = """
52#include <uapi/linux/ptrace.h>
53#include <net/sock.h>
54#include <bcc/proto.h>
55
56BPF_HASH(currsock, u32, struct sock *);
57
58// separate data structs for ipv4 and ipv6
59struct ipv4_data_t {
60    u64 ts_us;
61    u32 pid;
62    u32 saddr;
63    u32 daddr;
64    u64 ip;
65    u16 dport;
66    char task[TASK_COMM_LEN];
67};
68BPF_PERF_OUTPUT(ipv4_events);
69
70struct ipv6_data_t {
71    u64 ts_us;
72    u32 pid;
73    unsigned __int128 saddr;
74    unsigned __int128 daddr;
75    u64 ip;
76    u16 dport;
77    char task[TASK_COMM_LEN];
78};
79BPF_PERF_OUTPUT(ipv6_events);
80
81int trace_connect_entry(struct pt_regs *ctx, struct sock *sk)
82{
83    u32 pid = bpf_get_current_pid_tgid();
84    FILTER_PID
85
86    // stash the sock ptr for lookup on return
87    currsock.update(&pid, &sk);
88
89    return 0;
90};
91
92static int trace_connect_return(struct pt_regs *ctx, short ipver)
93{
94    int ret = PT_REGS_RC(ctx);
95    u32 pid = bpf_get_current_pid_tgid();
96
97    struct sock **skpp;
98    skpp = currsock.lookup(&pid);
99    if (skpp == 0) {
100        return 0;   // missed entry
101    }
102
103    if (ret != 0) {
104        // failed to send SYNC packet, may not have populated
105        // socket __sk_common.{skc_rcv_saddr, ...}
106        currsock.delete(&pid);
107        return 0;
108    }
109
110    // pull in details
111    struct sock *skp = *skpp;
112    u16 dport = skp->__sk_common.skc_dport;
113
114    FILTER_PORT
115
116    if (ipver == 4) {
117        struct ipv4_data_t data4 = {.pid = pid, .ip = ipver};
118        data4.ts_us = bpf_ktime_get_ns() / 1000;
119        data4.saddr = skp->__sk_common.skc_rcv_saddr;
120        data4.daddr = skp->__sk_common.skc_daddr;
121        data4.dport = ntohs(dport);
122        bpf_get_current_comm(&data4.task, sizeof(data4.task));
123        ipv4_events.perf_submit(ctx, &data4, sizeof(data4));
124
125    } else /* 6 */ {
126        struct ipv6_data_t data6 = {.pid = pid, .ip = ipver};
127        data6.ts_us = bpf_ktime_get_ns() / 1000;
128        bpf_probe_read(&data6.saddr, sizeof(data6.saddr),
129            skp->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
130        bpf_probe_read(&data6.daddr, sizeof(data6.daddr),
131            skp->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
132        data6.dport = ntohs(dport);
133        bpf_get_current_comm(&data6.task, sizeof(data6.task));
134        ipv6_events.perf_submit(ctx, &data6, sizeof(data6));
135    }
136
137    currsock.delete(&pid);
138
139    return 0;
140}
141
142int trace_connect_v4_return(struct pt_regs *ctx)
143{
144    return trace_connect_return(ctx, 4);
145}
146
147int trace_connect_v6_return(struct pt_regs *ctx)
148{
149    return trace_connect_return(ctx, 6);
150}
151"""
152
153# code substitutions
154if args.pid:
155    bpf_text = bpf_text.replace('FILTER_PID',
156        'if (pid != %s) { return 0; }' % args.pid)
157if args.port:
158    dports = [int(dport) for dport in args.port.split(',')]
159    dports_if = ' && '.join(['dport != %d' % ntohs(dport) for dport in dports])
160    bpf_text = bpf_text.replace('FILTER_PORT',
161        'if (%s) { currsock.delete(&pid); return 0; }' % dports_if)
162
163bpf_text = bpf_text.replace('FILTER_PID', '')
164bpf_text = bpf_text.replace('FILTER_PORT', '')
165
166if debug or args.ebpf:
167    print(bpf_text)
168    if args.ebpf:
169        exit()
170
171# event data
172TASK_COMM_LEN = 16      # linux/sched.h
173
174class Data_ipv4(ct.Structure):
175    _fields_ = [
176        ("ts_us", ct.c_ulonglong),
177        ("pid", ct.c_uint),
178        ("saddr", ct.c_uint),
179        ("daddr", ct.c_uint),
180        ("ip", ct.c_ulonglong),
181        ("dport", ct.c_ushort),
182        ("task", ct.c_char * TASK_COMM_LEN)
183    ]
184
185class Data_ipv6(ct.Structure):
186    _fields_ = [
187        ("ts_us", ct.c_ulonglong),
188        ("pid", ct.c_uint),
189        ("saddr", (ct.c_ulonglong * 2)),
190        ("daddr", (ct.c_ulonglong * 2)),
191        ("ip", ct.c_ulonglong),
192        ("dport", ct.c_ushort),
193        ("task", ct.c_char * TASK_COMM_LEN)
194    ]
195
196# process event
197def print_ipv4_event(cpu, data, size):
198    event = ct.cast(data, ct.POINTER(Data_ipv4)).contents
199    global start_ts
200    if args.timestamp:
201        if start_ts == 0:
202            start_ts = event.ts_us
203        print("%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), end="")
204    print("%-6d %-12.12s %-2d %-16s %-16s %-4d" % (event.pid,
205        event.task.decode('utf-8', 'replace'), event.ip,
206        inet_ntop(AF_INET, pack("I", event.saddr)),
207        inet_ntop(AF_INET, pack("I", event.daddr)), event.dport))
208
209def print_ipv6_event(cpu, data, size):
210    event = ct.cast(data, ct.POINTER(Data_ipv6)).contents
211    global start_ts
212    if args.timestamp:
213        if start_ts == 0:
214            start_ts = event.ts_us
215        print("%-9.3f" % ((float(event.ts_us) - start_ts) / 1000000), end="")
216    print("%-6d %-12.12s %-2d %-16s %-16s %-4d" % (event.pid,
217        event.task.decode('utf-8', 'replace'), event.ip,
218        inet_ntop(AF_INET6, event.saddr), inet_ntop(AF_INET6, event.daddr),
219        event.dport))
220
221# initialize BPF
222b = BPF(text=bpf_text)
223b.attach_kprobe(event="tcp_v4_connect", fn_name="trace_connect_entry")
224b.attach_kprobe(event="tcp_v6_connect", fn_name="trace_connect_entry")
225b.attach_kretprobe(event="tcp_v4_connect", fn_name="trace_connect_v4_return")
226b.attach_kretprobe(event="tcp_v6_connect", fn_name="trace_connect_v6_return")
227
228# header
229if args.timestamp:
230    print("%-9s" % ("TIME(s)"), end="")
231print("%-6s %-12s %-2s %-16s %-16s %-4s" % ("PID", "COMM", "IP", "SADDR",
232    "DADDR", "DPORT"))
233
234start_ts = 0
235
236# read events
237b["ipv4_events"].open_perf_buffer(print_ipv4_event)
238b["ipv6_events"].open_perf_buffer(print_ipv6_event)
239while 1:
240    b.perf_buffer_poll()
241