tcpaccept.py 8.42 KiB
#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
# tcpaccept Trace TCP accept()s.
#           For Linux, uses BCC, eBPF. Embedded C.
# USAGE: tcpaccept [-h] [-t] [-p PID]
# This uses dynamic tracing of the kernel inet_csk_accept() socket function
# (from tcp_prot.accept), and will need to be modified to match kernel changes.
# Copyright (c) 2015 Brendan Gregg.
# Licensed under the Apache License, Version 2.0 (the "License")
# 13-Oct-2015   Brendan Gregg   Created this.
# 14-Feb-2016      "      "     Switch to bpf_perf_output.
from __future__ import print_function
from bcc import BPF
from socket import inet_ntop, AF_INET, AF_INET6
from struct import pack
import argparse
import ctypes as ct
# arguments
examples = """examples:
    ./tcpaccept           # trace all TCP accept()s
    ./tcpaccept -t        # include timestamps
    ./tcpaccept -p 181    # only trace PID 181
"""
parser = argparse.ArgumentParser(
    description="Trace TCP accepts",
    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("--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>
// separate data structs for ipv4 and ipv6
struct ipv4_data_t {
    // XXX: switch some to u32's when supported
    u64 ts_us;
    u64 pid;
    u32 saddr;
    u32 daddr;
    u64 ip;
    u64 lport;
    char task[TASK_COMM_LEN];
BPF_PERF_OUTPUT(ipv4_events);
struct ipv6_data_t {
    u64 ts_us;
    u64 pid;
    unsigned __int128 saddr;
    unsigned __int128 daddr;
    u64 ip;
    u64 lport;
    char task[TASK_COMM_LEN];
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}; BPF_PERF_OUTPUT(ipv6_events); """ # # The following is the code for older kernels(Linux pre-4.16). # It uses kprobes to instrument inet_csk_accept(). On Linux 4.16 and # later, the sock:inet_sock_set_state tracepoint should be used instead, as # is done by the code that follows this. # bpf_text_kprobe = """ int kretprobe__inet_csk_accept(struct pt_regs *ctx) { struct sock *newsk = (struct sock *)PT_REGS_RC(ctx); u32 pid = bpf_get_current_pid_tgid(); if (newsk == NULL) return 0; // check this is TCP u8 protocol = 0; // workaround for reading the sk_protocol bitfield: // Following comments add by Joe Yin: // Unfortunately,it can not work since Linux 4.10, // because the sk_wmem_queued is not following the bitfield of sk_protocol. // And the following member is sk_gso_max_segs. // So, we can use this: // bpf_probe_read(&protocol, 1, (void *)((u64)&newsk->sk_gso_max_segs) - 3); // In order to diff the pre-4.10 and 4.10+ ,introduce the variables gso_max_segs_offset,sk_lingertime, // sk_lingertime is closed to the gso_max_segs_offset,and // the offset between the two members is 4 int gso_max_segs_offset = offsetof(struct sock, sk_gso_max_segs); int sk_lingertime_offset = offsetof(struct sock, sk_lingertime); if (sk_lingertime_offset - gso_max_segs_offset == 4) // 4.10+ with little endian #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ protocol = *(u8 *)((u64)&newsk->sk_gso_max_segs - 3); else // pre-4.10 with little endian protocol = *(u8 *)((u64)&newsk->sk_wmem_queued - 3); #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ // 4.10+ with big endian protocol = *(u8 *)((u64)&newsk->sk_gso_max_segs - 1); else // pre-4.10 with big endian protocol = *(u8 *)((u64)&newsk->sk_wmem_queued - 1); #else # error "Fix your compiler's __BYTE_ORDER__?!" #endif if (protocol != IPPROTO_TCP) return 0; // pull in details u16 family = 0, lport = 0; family = newsk->__sk_common.skc_family; lport = newsk->__sk_common.skc_num; if (family == AF_INET) { struct ipv4_data_t data4 = {.pid = pid, .ip = 4}; data4.ts_us = bpf_ktime_get_ns() / 1000; data4.saddr = newsk->__sk_common.skc_rcv_saddr; data4.daddr = newsk->__sk_common.skc_daddr; data4.lport = lport; bpf_get_current_comm(&data4.task, sizeof(data4.task)); ipv4_events.perf_submit(ctx, &data4, sizeof(data4));
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} else if (family == AF_INET6) { struct ipv6_data_t data6 = {.pid = pid, .ip = 6}; data6.ts_us = bpf_ktime_get_ns() / 1000; bpf_probe_read(&data6.saddr, sizeof(data6.saddr), &newsk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32); bpf_probe_read(&data6.daddr, sizeof(data6.daddr), &newsk->__sk_common.skc_v6_daddr.in6_u.u6_addr32); data6.lport = lport; bpf_get_current_comm(&data6.task, sizeof(data6.task)); ipv6_events.perf_submit(ctx, &data6, sizeof(data6)); } // else drop return 0; } """ bpf_text_tracepoint = """ TRACEPOINT_PROBE(sock, inet_sock_set_state) { if (args->protocol != IPPROTO_TCP) return 0; u32 pid = bpf_get_current_pid_tgid(); // pull in details u16 family = 0, lport = 0; family = args->family; lport = args->sport; if (family == AF_INET) { struct ipv4_data_t data4 = {.pid = pid, .ip = 4}; data4.ts_us = bpf_ktime_get_ns() / 1000; __builtin_memcpy(&data4.saddr, args->saddr, sizeof(data4.saddr)); __builtin_memcpy(&data4.daddr, args->daddr, sizeof(data4.daddr)); data4.lport = lport; bpf_get_current_comm(&data4.task, sizeof(data4.task)); ipv4_events.perf_submit(args, &data4, sizeof(data4)); } else if (family == AF_INET6) { struct ipv6_data_t data6 = {.pid = pid, .ip = 6}; data6.ts_us = bpf_ktime_get_ns() / 1000; __builtin_memcpy(&data6.saddr, args->saddr, sizeof(data6.saddr)); __builtin_memcpy(&data6.daddr, args->daddr, sizeof(data6.daddr)); data6.lport = lport; bpf_get_current_comm(&data6.task, sizeof(data6.task)); ipv6_events.perf_submit(args, &data6, sizeof(data6)); } // else drop return 0; } """ if (BPF.tracepoint_exists("sock", "inet_sock_set_state")): bpf_text += bpf_text_tracepoint else: bpf_text += bpf_text_kprobe # code substitutions if args.pid: bpf_text = bpf_text.replace('FILTER', 'if (pid != %s) { return 0; }' % args.pid) else: bpf_text = bpf_text.replace('FILTER', '') if debug or args.ebpf: print(bpf_text) if args.ebpf: exit() # event data TASK_COMM_LEN = 16 # linux/sched.h