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filegone.py
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filegone.py
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#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
#
# filegone Trace why file gone (deleted or renamed).
# For Linux, uses BCC, eBPF. Embedded C.
#
# USAGE: filegone [-h] [-p PID]
#
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 08-Nov-2022 Curu. modified from filelife
# 19-Nov-2022 Rong Tao Check btf struct field instead of KERNEL_VERSION macro.
from __future__ import print_function
from bcc import BPF
import argparse
from time import strftime
# arguments
examples = """examples:
./filegone # trace all file gone events
./filegone -p 181 # only trace PID 181
"""
parser = argparse.ArgumentParser(
description="Trace why file gone (deleted or renamed)",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
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 <linux/fs.h>
#include <linux/sched.h>
struct data_t {
u32 pid;
u8 action;
char comm[TASK_COMM_LEN];
char fname[DNAME_INLINE_LEN];
char fname2[DNAME_INLINE_LEN];
};
BPF_PERF_OUTPUT(events);
// trace file deletion and output details
TRACE_VFS_UNLINK_FUNC
{
u32 pid = bpf_get_current_pid_tgid() >> 32;
FILTER
struct data_t data = {};
struct qstr d_name = dentry->d_name;
if (d_name.len == 0)
return 0;
bpf_get_current_comm(&data.comm, sizeof(data.comm));
data.pid = pid;
data.action = 'D';
bpf_probe_read(&data.fname, sizeof(data.fname), d_name.name);
events.perf_submit(ctx, &data, sizeof(data));
return 0;
}
// trace file rename
TRACE_VFS_RENAME_FUNC
u32 pid = bpf_get_current_pid_tgid() >> 32;
FILTER
struct data_t data = {};
struct qstr s_name = old_dentry->d_name;
struct qstr d_name = new_dentry->d_name;
if (s_name.len == 0 || d_name.len == 0)
return 0;
bpf_get_current_comm(&data.comm, sizeof(data.comm));
data.pid = pid;
data.action = 'R';
bpf_probe_read(&data.fname, sizeof(data.fname), s_name.name);
bpf_probe_read(&data.fname2, sizeof(data.fname), d_name.name);
events.perf_submit(ctx, &data, sizeof(data));
return 0;
}
"""
bpf_vfs_rename_text_old="""
int trace_rename(struct pt_regs *ctx, struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
"""
bpf_vfs_rename_text_new="""
int trace_rename(struct pt_regs *ctx, struct renamedata *rd)
{
struct dentry *old_dentry = rd->old_dentry;
struct dentry *new_dentry = rd->new_dentry;
"""
bpf_vfs_unlink_text_old="""
int trace_unlink(struct pt_regs *ctx, struct inode *dir, struct dentry *dentry)
"""
bpf_vfs_unlink_text_new="""
int trace_unlink(struct pt_regs *ctx, struct user_namespace *ns, struct inode *dir, struct dentry *dentry)
"""
def action2str(action):
if chr(action) == 'D':
action_str = "DELETE"
else:
action_str = "RENAME"
return action_str
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()
# check 'struct renamedata' exist or not
if BPF.kernel_struct_has_field("renamedata", "old_mnt_userns") == 1:
bpf_text = bpf_text.replace('TRACE_VFS_RENAME_FUNC', bpf_vfs_rename_text_new)
bpf_text = bpf_text.replace('TRACE_VFS_UNLINK_FUNC', bpf_vfs_unlink_text_new)
else:
bpf_text = bpf_text.replace('TRACE_VFS_RENAME_FUNC', bpf_vfs_rename_text_old)
bpf_text = bpf_text.replace('TRACE_VFS_UNLINK_FUNC', bpf_vfs_unlink_text_old)
# initialize BPF
b = BPF(text=bpf_text)
b.attach_kprobe(event="vfs_unlink", fn_name="trace_unlink")
b.attach_kprobe(event="vfs_rmdir", fn_name="trace_unlink")
b.attach_kprobe(event="vfs_rename", fn_name="trace_rename")
# header
print("%-8s %-7s %-16s %6s %s" % ("TIME", "PID", "COMM", "ACTION", "FILE"))
# process event
def print_event(cpu, data, size):
event = b["events"].event(data)
action_str = action2str(event.action)
file_str = event.fname.decode('utf-8', 'replace')
if action_str == "RENAME":
file_str = "%s > %s" % (file_str, event.fname2.decode('utf-8', 'replace'))
print("%-8s %-7d %-16s %6s %s" % (strftime("%H:%M:%S"), event.pid,
event.comm.decode('utf-8', 'replace'), action_str, file_str))
b["events"].open_perf_buffer(print_event)
while 1:
try:
b.perf_buffer_poll()
except KeyboardInterrupt:
exit()