Messages in this thread | | | Date | Thu, 1 Apr 2004 18:48:22 -0800 | From | Chris Wright <> | Subject | Re: disable-cap-mlock |
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* Andrea Arcangeli (andrea@suse.de) wrote: > On Thu, Apr 01, 2004 at 06:21:27PM -0800, Chris Wright wrote: > > Ah, yes I see what you are saying. This is the same issue with normal > > pages and SHM_LOCK that I mentioned earlier, I believe. I don't see the > > best solution, because once you detach w/out any destroy, there could be > > nobody to assign the accounting to. Do you agree? > > yes, rlimit just can't account for shmget(SHM_HUGETLB) and > shmctl(SHM_LOCK) either, because it can only account the stuff that you > temporarily have in the address space. > > the exploit is simply to shmget tons of 2M hugepage segments, and to > shmat/shmdt all of them, then you'll pin N times those 2M largepages, > and they will not be accounted anywhere allowing anybody to pin as much > memory as they want.
Yup. I had an earlier patch against 2.4 that created a max count for pages lockable by unprivileged users. So the accounting was done against a global pool, and mitigated the DoS damage to those trying to share this pool. I think it was more of a hack, though.
thanks, -chris -- Linux Security Modules http://lsm.immunix.org http://lsm.bkbits.net - 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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