Man strace, or http://subterfugue.org
> 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 [EMAIL PROTECTED]
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