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349 lines
8.4 KiB
349 lines
8.4 KiB
#!/usr/bin/env python
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# @lint-avoid-python-3-compatibility-imports
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#
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# sofdsnoop traces file descriptors passed via socket
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: sofdsnoop
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#
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# Copyright (c) 2018 Jiri Olsa.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 30-Jul-2018 Jiri Olsa Created this.
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from __future__ import print_function
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from bcc import ArgString, BPF
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import os
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import argparse
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import ctypes as ct
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from datetime import datetime, timedelta
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# arguments
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examples = """examples:
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./sofdsnoop # trace file descriptors passes
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./sofdsnoop -T # include timestamps
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./sofdsnoop -p 181 # only trace PID 181
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./sofdsnoop -t 123 # only trace TID 123
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./sofdsnoop -d 10 # trace for 10 seconds only
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./sofdsnoop -n main # only print process names containing "main"
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"""
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parser = argparse.ArgumentParser(
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description="Trace file descriptors passed via socket",
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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("-t", "--tid",
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help="trace this TID only")
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parser.add_argument("-n", "--name",
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type=ArgString,
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help="only print process names containing this name")
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parser.add_argument("-d", "--duration",
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help="total duration of trace in seconds")
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args = parser.parse_args()
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debug = 0
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ACTION_SEND=0
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ACTION_RECV=1
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MAX_FD=10
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if args.duration:
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args.duration = timedelta(seconds=int(args.duration))
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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 <uapi/linux/limits.h>
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#include <linux/sched.h>
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#include <linux/socket.h>
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#include <net/sock.h>
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#define MAX_FD 10
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#define ACTION_SEND 0
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#define ACTION_RECV 1
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struct val_t {
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u64 id;
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u64 ts;
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int action;
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int sock_fd;
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int fd_cnt;
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int fd[MAX_FD];
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char comm[TASK_COMM_LEN];
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};
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BPF_HASH(detach_ptr, u64, struct cmsghdr *);
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BPF_HASH(sock_fd, u64, int);
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BPF_PERF_OUTPUT(events);
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static void set_fd(int fd)
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{
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u64 id = bpf_get_current_pid_tgid();
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sock_fd.update(&id, &fd);
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}
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static int get_fd(void)
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{
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u64 id = bpf_get_current_pid_tgid();
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int *fd;
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fd = sock_fd.lookup(&id);
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return fd ? *fd : -1;
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}
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static void put_fd(void)
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{
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u64 id = bpf_get_current_pid_tgid();
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sock_fd.delete(&id);
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}
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static int sent_1(struct pt_regs *ctx, struct val_t *val, int num, void *data)
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{
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val->fd_cnt = min(num, MAX_FD);
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if (bpf_probe_read(&val->fd[0], MAX_FD * sizeof(int), data))
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return -1;
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events.perf_submit(ctx, val, sizeof(*val));
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return 0;
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}
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#define SEND_1 \
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if (sent_1(ctx, &val, num, (void *) data)) \
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return 0; \
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\
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num -= MAX_FD; \
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if (num < 0) \
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return 0; \
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\
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data += MAX_FD;
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#define SEND_2 SEND_1 SEND_1
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#define SEND_4 SEND_2 SEND_2
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#define SEND_8 SEND_4 SEND_4
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#define SEND_260 SEND_8 SEND_8 SEND_8 SEND_2
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static int send(struct pt_regs *ctx, struct cmsghdr *cmsg, int action)
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{
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struct val_t val = { 0 };
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int *data, num, fd;
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u64 tsp = bpf_ktime_get_ns();
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data = (void *) ((char *) cmsg + sizeof(struct cmsghdr));
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num = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
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val.id = bpf_get_current_pid_tgid();
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val.action = action;
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val.sock_fd = get_fd();
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val.ts = tsp / 1000;
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if (bpf_get_current_comm(&val.comm, sizeof(val.comm)) != 0)
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return 0;
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SEND_260
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return 0;
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}
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static bool allow_pid(u64 id)
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{
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u32 pid = id >> 32; // PID is higher part
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u32 tid = id; // Cast and get the lower part
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FILTER
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return 1;
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}
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int trace_scm_send_entry(struct pt_regs *ctx, struct socket *sock, struct msghdr *hdr)
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{
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struct cmsghdr *cmsg = NULL;
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if (!allow_pid(bpf_get_current_pid_tgid()))
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return 0;
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if (hdr->msg_controllen >= sizeof(struct cmsghdr))
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cmsg = hdr->msg_control;
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if (!cmsg || (cmsg->cmsg_type != SCM_RIGHTS))
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return 0;
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return send(ctx, cmsg, ACTION_SEND);
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};
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int trace_scm_detach_fds_entry(struct pt_regs *ctx, struct msghdr *hdr)
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{
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struct cmsghdr *cmsg = NULL;
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u64 id = bpf_get_current_pid_tgid();
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if (!allow_pid(id))
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return 0;
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if (hdr->msg_controllen >= sizeof(struct cmsghdr))
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cmsg = hdr->msg_control;
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if (!cmsg)
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return 0;
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detach_ptr.update(&id, &cmsg);
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return 0;
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};
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int trace_scm_detach_fds_return(struct pt_regs *ctx)
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{
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struct cmsghdr **cmsgp;
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u64 id = bpf_get_current_pid_tgid();
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if (!allow_pid(id))
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return 0;
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cmsgp = detach_ptr.lookup(&id);
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if (!cmsgp)
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return 0;
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return send(ctx, *cmsgp, ACTION_RECV);
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}
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int syscall__sendmsg(struct pt_regs *ctx, u64 fd, u64 msg, u64 flags)
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{
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struct pt_regs p;
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if (!allow_pid(bpf_get_current_pid_tgid()))
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return 0;
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set_fd(fd);
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return 0;
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}
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int trace_sendmsg_return(struct pt_regs *ctx)
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{
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if (!allow_pid(bpf_get_current_pid_tgid()))
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return 0;
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put_fd();
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return 0;
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}
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int syscall__recvmsg(struct pt_regs *ctx, u64 fd, u64 msg, u64 flags)
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{
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struct pt_regs p;
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if (!allow_pid(bpf_get_current_pid_tgid()))
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return 0;
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fd = fd;
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set_fd(fd);
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return 0;
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}
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int trace_recvmsg_return(struct pt_regs *ctx)
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{
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if (!allow_pid(bpf_get_current_pid_tgid()))
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return 0;
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put_fd();
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return 0;
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}
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"""
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if args.tid: # TID trumps PID
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bpf_text = bpf_text.replace('FILTER',
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'if (tid != %s) { return 0; }' % args.tid)
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elif 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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# initialize BPF
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b = BPF(text=bpf_text)
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syscall_fnname = b.get_syscall_fnname("sendmsg")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__sendmsg")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_sendmsg_return")
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syscall_fnname = b.get_syscall_fnname("recvmsg")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__recvmsg")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_recvmsg_return")
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b.attach_kprobe(event="__scm_send", fn_name="trace_scm_send_entry")
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b.attach_kprobe(event="scm_detach_fds", fn_name="trace_scm_detach_fds_entry")
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b.attach_kretprobe(event="scm_detach_fds", fn_name="trace_scm_detach_fds_return")
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TASK_COMM_LEN = 16 # linux/sched.h
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initial_ts = 0
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class Data(ct.Structure):
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_fields_ = [
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("id", ct.c_ulonglong),
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("ts", ct.c_ulonglong),
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("action", ct.c_int),
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("sock_fd", ct.c_int),
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("fd_cnt", ct.c_int),
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("fd", ct.c_int * MAX_FD),
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("comm", ct.c_char * TASK_COMM_LEN),
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]
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# header
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if args.timestamp:
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print("%-14s" % ("TIME(s)"), end="")
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print("%-6s %-6s %-16s %-25s %-5s %s" %
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("ACTION", "TID", "COMM", "SOCKET", "FD", "NAME"))
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def get_file(pid, fd):
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proc = "/proc/%d/fd/%d" % (pid, fd)
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try:
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return os.readlink(proc)
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except OSError as err:
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return "N/A"
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# process event
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def print_event(cpu, data, size):
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event = ct.cast(data, ct.POINTER(Data)).contents
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tid = event.id & 0xffffffff;
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cnt = min(MAX_FD, event.fd_cnt);
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if args.name and bytes(args.name) not in event.comm:
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return
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for i in range(0, cnt):
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global initial_ts
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if not initial_ts:
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initial_ts = event.ts
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if args.timestamp:
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delta = event.ts - initial_ts
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print("%-14.9f" % (float(delta) / 1000000), end="")
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print("%-6s %-6d %-16s " %
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("SEND" if event.action == ACTION_SEND else "RECV",
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tid, event.comm.decode()), end = '')
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sock = "%d:%s" % (event.sock_fd, get_file(tid, event.sock_fd))
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print("%-25s " % sock, end = '')
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fd = event.fd[i]
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fd_file = get_file(tid, fd) if event.action == ACTION_SEND else ""
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print("%-5d %s" % (fd, fd_file))
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# loop with callback to print_event
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b["events"].open_perf_buffer(print_event, page_cnt=64)
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start_time = datetime.now()
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while not args.duration or datetime.now() - start_time < args.duration:
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try:
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b.perf_buffer_poll(timeout=1000)
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except KeyboardInterrupt:
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exit()
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