On Wed, May 27, 2009 at 04:37:18PM +0900, KAMEZAWA Hiroyuki wrote:
> On Wed, 27 May 2009 16:06:03 +0900
> "Ken'ichi Ohmichi" <[email protected]> wrote:
> 
> > 
> > Hi,
> > 
> > KAMEZAWA Hiroyuki wrote:
> > >>>>> This patchset adds a new rule based on process name.
> > >>>>> I have some TODOS, so this patchset is not complete.
> > >>>>> I'd like to talk about them, any comment is welcome.
> > >>>>>
> > >>>>> TODOS:
> > >>>>> ======
> > >>>>> * The cgroup directory, which is specified by `cgexec` command, is
> > >>>>>   ignored because this patch adds an EXEC event to the event handler.
> > >>>>>   This problem should be fixed.
> > >>>>>
> > >>>>> * Think about the length of process name.
> > >>>>>   A process name is taken from /proc/<pid>/status file, and the name
> > >>>>>   is shortened to 15 characters if the real name is over than 16
> > >>>>>   characters. That is a linux kernel's behavior. Should we consider
> > >>>>>   a process name in /etc/cgrules.conf as 15 characters, if it is over
> > >>>>>   than 16 characters like a linux kernel ?
> > >>>>>
> > >>>> I'm sorry that I don't read the whole patch precisely.
> > >>>>
> > >>>> Why based on "process name", why not "exec file" ?
> > >>>> Do you have special reason ?
> > >>> One disadvantage of exe file I can think of is "script" file.
> > >>> But /proc/xxx/status's information is too naive.
> > >>>
> > >>> Can't you parse /proc/xxx/cmdline file and check "what's really 
> > >>> executed ?"
> > >>> Parser can be very difficult ?
> > >> Good point. We can parse /proc/xxx/cmdline instead of /proc/xxx/status
> > >> for getting a process name, and that is better than current patch.
> > >> But I have one concern. The /proc/xxx/cmdline file of a kernel thread is
> > >> empty, and we cannot get the name from the file.
> > >> How about getting a process name from a /proc/xxx/status file only if
> > >> /proc/xxx/cmdline is empty ?
> > >>
> > > Maybe good. For example, "ps" does [kthread] for tasks with empty cmdline.
> > > 
> > > But, IIUC, a script like
> > > 
> > > %./myscript.sh
> > > 
> > > has cmdline as /bin/bash ./myscript.sh and "status" file includes 
> > > "myscript.sh"
> > > So, there may be 3 ways for specifing a task by name.
> > > 
> > > exe:/bin/bash         # full-path name of executable file (but can't 
> > > handle scripts)
> > > comm:myscript.sh      # name of executable file
> > > cmdline:/bin/bash myscript.sh # cmdline
> > > 
> > > Then, having "exe" and "comm" is maybe good....maybe.
> > 
> > I guess you means the following, right ?
> > 
> > * libcgroup should distinguish "exec file" or "script file" of each
> >   process automatically.
> > 
> > * If "exec file", the first arg in /proc/<pid>/cmdline is checked.
> >   In your example, the first arg means /bin/bash.
> > 
> > * If "script file", the item of "Name:" in /proc/<pid>/status is checked.
> >   In your example, the item means myscript.sh.
> > 
> I have no objections if we have clear rule.
> If I was you, I'll write following logic.
> 
> NEW)      <user>:(<ops>=):<process name>  <controllers>   <destination>
> 
> ops can be "exe", "comm", "cmdline"
> 
>      exe=/bin/bash
> or
>      comm=myscript.sh
> or
>      cmdline="/bin/bash /home/kamezawa/bin/myscript.sh"
> 
> Complicated ?

Quite complicated actually. What this would mean is that we would also
need some tool which could write the config files out. I am not sure if
this is the way we want to proceed forward in.

> I have no strong opinion but I feel only "comm" can be too short for
> enterprise users. I saw 3 version of "java" runs under different applications
> in user's environment, all uid were "root". (oh, yes, seems crazy ;)
> 

True, but I think we need to keep the configuration file as simple as
possible for it to be useful.

Thanks,
-- 
regards,
Dhaval

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