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135 lines
3.9 KiB
135 lines
3.9 KiB
#!/usr/bin/env python
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# @lint-avoid-python-3-compatibility-imports
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#
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# tcpaccept Trace TCP accept()s.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: tcpaccept [-h] [-t] [-p PID]
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#
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# This uses dynamic tracing of the kernel inet_csk_accept() socket function
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# (from tcp_prot.accept), and will need to be modified to match kernel changes.
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#
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# IPv4 addresses are printed as dotted quads. For IPv6 addresses, the last four
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# bytes are printed after "..."; check for future versions with better IPv6
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# support.
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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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# 13-Oct-2015 Brendan Gregg Created this.
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from __future__ import print_function
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from bcc import BPF
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import argparse
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# arguments
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examples = """examples:
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./tcpaccept # trace all TCP accept()s
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./tcpaccept -t # include timestamps
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./tcpaccept -p 181 # only trace PID 181
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"""
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parser = argparse.ArgumentParser(
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description="Trace TCP accepts",
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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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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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int kretprobe__inet_csk_accept(struct pt_regs *ctx)
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{
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struct sock *newsk = (struct sock *)PT_REGS_RC(ctx);
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u32 pid = bpf_get_current_pid_tgid();
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if (newsk == NULL)
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return 0;
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// check this is TCP
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u8 protocol = 0;
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// workaround for reading the sk_protocol bitfield:
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bpf_probe_read(&protocol, 1, (void *)((long)&newsk->sk_wmem_queued) - 3);
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if (protocol != IPPROTO_TCP)
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return 0;
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// pull in details
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u16 family = 0, lport = 0;
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u32 saddr = 0, daddr = 0;
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bpf_probe_read(&family, sizeof(family), &newsk->__sk_common.skc_family);
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bpf_probe_read(&lport, sizeof(lport), &newsk->__sk_common.skc_num);
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if (family == AF_INET) {
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bpf_probe_read(&saddr, sizeof(saddr),
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&newsk->__sk_common.skc_rcv_saddr);
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bpf_probe_read(&daddr, sizeof(daddr),
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&newsk->__sk_common.skc_daddr);
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// output
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bpf_trace_printk("4 %x %x %d\\n", daddr, saddr, lport);
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} else if (family == AF_INET6) {
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// just grab the last 4 bytes for now
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bpf_probe_read(&saddr, sizeof(saddr),
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&newsk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32[3]);
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bpf_probe_read(&daddr, sizeof(daddr),
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&newsk->__sk_common.skc_v6_daddr.in6_u.u6_addr32[3]);
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// output and flip byte order of addresses
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bpf_trace_printk("6 %x %x %d\\n", bpf_ntohl(daddr),
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bpf_ntohl(saddr), lport);
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}
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// else drop
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return 0;
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}
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"""
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# code substitutions
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if args.pid:
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bpf_text = bpf_text.replace('FILTER',
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'if (pid != %s) { return 0; }' % args.pid)
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else:
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bpf_text = bpf_text.replace('FILTER', '')
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if debug:
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print(bpf_text)
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# initialize BPF
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b = BPF(text=bpf_text)
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# header
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if args.timestamp:
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print("%-9s" % ("TIME(s)"), end="")
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print("%-6s %-12s %-2s %-16s %-16s %-4s" % ("PID", "COMM", "IP", "RADDR",
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"LADDR", "LPORT"))
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start_ts = 0
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def inet_ntoa(addr):
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dq = ''
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for i in range(0, 4):
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dq = dq + str(addr & 0xff)
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if (i != 3):
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dq = dq + '.'
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addr = addr >> 8
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return dq
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# format output
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while 1:
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(task, pid, cpu, flags, ts, msg) = b.trace_fields()
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(ip_s, raddr_hs, laddr_hs, lport_s) = msg.split(" ")
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if args.timestamp:
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if start_ts == 0:
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start_ts = ts
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print("%-9.3f" % (ts - start_ts), end="")
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print("%-6d %-12.12s %-2s %-16s %-16s %-4s" % (pid, task, ip_s,
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inet_ntoa(int(raddr_hs, 16)) if ip_s == "4" else "..." + raddr_hs,
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inet_ntoa(int(laddr_hs, 16)) if ip_s == "4" else "..." + laddr_hs,
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lport_s))
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