Messages in this thread | | | Date | Wed, 10 Oct 2007 01:15:23 -0400 | From | Gustavo Chain <> | Subject | Re: [PATCH] Reserve N process to root |
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El Wed, 10 Oct 2007 11:19:27 +0930 David Newall <david@davidnewall.com> escribió:
> Gustavo Chain wrote: > > I think it's necessary to reserve some pids to the super user. > > 5 must be sufficient. > > Why? (Sorry if I missed something.)
To prevent a posible DoS ?
> > Shouldn't you test for error return before the pid is allocated? > Otherwise, I think, you have to free it. Thus: > > long do_fork(unsigned long clone_flags, > > int __user *parent_tidptr, > > int __user *child_tidptr) > > { > > +#define RESERVED_PIDS 5 /* danged if I know why */ > > + > > + if (!capable(CAP_SYS_ADMIN) && nr_threads >= max_threads - > > RESERVED_PIDS) > > + return -EAGAIN; > > + > > > > struct task_struct *p; > > int trace = 0; > > struct pid *pid = alloc_pid(); > > long nr; > > > > if (!pid) > > return -EAGAIN; > > nr = pid->nr; > > > > (While I'm being picky, I don't like braces around a simple return, > and neither, I note, does the style guide.) > - > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- Gustavo Chaín Dumit - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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