Messages in this thread Patch in this message |  | | Date | Tue, 28 Nov 2000 22:11:55 +0100 | From | Jan Rekorajski <> | Subject | Re: [PATCH] no RLIMIT_NPROC for root, please |
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On Tue, 28 Nov 2000, Tigran Aivazian wrote:
> On Tue, 28 Nov 2000, Jan Rekorajski wrote: > > --- linux/kernel/fork.c~ Tue Sep 5 23:48:59 2000 > > +++ linux/kernel/fork.c Sun Nov 26 20:22:20 2000 > > @@ -560,7 +560,8 @@ > > *p = *current; > > > > retval = -EAGAIN; > > - if (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur) > > + if (p->user->uid && > > + (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur)) > > Jan, > > Hardcoding things signifying special treatment of uid=0 is almost always a > bad idea. If you _really_ think that superuser (whatever entity that might > be) should be exempt from RLIMIT_NPROC and can prove that (SuSv2 seems to > be silent so you may be right), then you should use capable() to do proper > capability test and not that horrible explicit uid test as in your patch > above.
Ok, how about setting limits on login? When this looks like:
--- uid = 0 here setrlimit(RLIMIT_NPROC, n) fork() <- this will fail if root has >n processes setuid(user)
and it is hard to change this sequence, all PAM enabled apps depend on it :(
The other scenario may be when root has already n processes, call them system stuff, and cannot login or even kill anything because of limits.
Is this patch better? I put CAP_SYS_RESOURCE, but maybe it should be CAP_SYS_ADMIN.
--- linux/kernel/fork.c~ Fri Nov 17 15:09:26 2000 +++ linux/kernel/fork.c Tue Nov 28 22:02:17 2000 @@ -562,7 +562,8 @@ *p = *current; retval = -EAGAIN; - if (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur) + if ((atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur) && + !capable(CAP_SYS_RESOURCE)) goto bad_fork_free; atomic_inc(&p->user->__count); atomic_inc(&p->user->processes); Jan -- Jan Rękorajski | ALL SUSPECTS ARE GUILTY. PERIOD! baggins<at>mimuw.edu.pl | OTHERWISE THEY WOULDN'T BE SUSPECTS, WOULD THEY? BOFH, type MANIAC | -- TROOPS by Kevin Rubio - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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