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Hello,
I'm not very experienced with dealing directly with the kernel, so I was
hoping for a little advice...
I'd like to implement some sort of rudimentary (file)system-call logging.
Specifically, I'd like information about write, open, creat, unlink, and
maybe a few others to be pushed into userspace. Mostly, I'd just like to
know what files are being created, modified, and deleted as it happens.
It seems quite easy to me -- I was thinking of doing this with a module.
I'll just grab the pointer from sys_call_table[__NR_open] and replace it with
my own little wrapper that does nothing but call the original function, and
then log the call in some manner.
================
asmlinkage int my_sys_open(const char *fname, int flags, int mode)
{
[preliminary stuff]
returnval = real_sys_open(fname, flags, mode);
[log information based on returnval, fname, whatever];
return returnval;
}
int init_module()
{
[other stuff]
real_sys_open = sys_call_table[__NR_open];
sys_call_table[__NR_open] = my_sys_open;
return 0;
}
init cleanup_module()
{
sys_call_table[__NR_open] = real_sys_open;
}
===========
The simplicity of the whole thing is what scares me a little bit. Am I being
horribly naive about something here? It seems like an obviously useful
module to have around, and yet I've never seen it and I couldn't find anyone
who had done it already. Is there a much better way to accomplish this than
loading in a module? Am I risking serious fs corruption?
It occurs to me that I may have some problems if something else changes the
sys_call_table[__NR_open] and the two modules don't cooperate...
Thanks.
- --
Chad Hogan chad.hogan@inphinity.com
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This archive was generated by hypermail 2b29 : Sun Apr 15 2001 - 21:00:20 EST