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60 lines
1.4 KiB
60 lines
1.4 KiB
#!/usr/bin/env python
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#
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# strlen_snoop Trace strlen() library function for a given PID.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: strlensnoop PID
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#
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# Try running this on a separate bash shell.
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#
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# Written as a basic example of BCC and uprobes.
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#
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# Copyright 2016 Netflix, Inc.
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# Licensed under the Apache License, Version 2.0 (the "License")
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from __future__ import print_function
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from bcc import BPF
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from os import getpid
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import sys
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if len(sys.argv) < 2:
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print("USAGE: strlensnoop PID")
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exit()
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pid = sys.argv[1]
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# load BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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int printarg(struct pt_regs *ctx) {
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if (!PT_REGS_PARM1(ctx))
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return 0;
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u32 pid = bpf_get_current_pid_tgid();
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if (pid != PID)
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return 0;
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char str[80] = {};
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bpf_probe_read(&str, sizeof(str), (void *)PT_REGS_PARM1(ctx));
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bpf_trace_printk("%s\\n", &str);
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return 0;
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};
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"""
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bpf_text = bpf_text.replace('PID', pid)
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b = BPF(text=bpf_text)
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b.attach_uprobe(name="c", sym="strlen", fn_name="printarg")
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# header
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print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "STRLEN"))
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# format output
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me = getpid()
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while 1:
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try:
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(task, pid, cpu, flags, ts, msg) = b.trace_fields()
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except ValueError:
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continue
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if pid == me or msg == "":
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continue
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print("%-18.9f %-16s %-6d %s" % (ts, task, pid, msg))
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