Messages in this thread | | | Date | Thu, 19 Jan 2012 10:55:41 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [RFC] syscalls, x86: Add __NR_kcmp syscall |
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On Wed, Jan 18, 2012 at 03:29:50PM -0800, Eric W. Biederman wrote: > > > > It doesn't matter. Even if we take a list of objects the kernel either > > should return us some ordering info or find duplicates, in any case it > > makes things more complex i think. So we wanted to bring some minimum > > into kernel leaving the rest of work to user-space. > > Agreed a syscall does the duplication is probably not the way to go. > > A syscall that takes a huge list of objects would solve any security > concerns that we have with returning the object order to user space if > done carefully, but it would require a bunch of additional user space > and kernel memory. >
yes, an it increase syscall time itself since we will have to provide this memory dynamically
> Sometimes taking a data structure transforming it into a weird form for > a specific task and then transforming the data structure back to it's > original form is a useful way to go. So I think a general kernel object > deduplicating system call is an interesting plan B, but a straight > comparison function if we can make it work is a lot more flexible and > useful. >
I hope the root-only restriction would resolve the potential security problem, since as I mentioned if I've hijacked the machine and already goot root -- mem order is not that interesting info I could obtain from such computer :)
Cyrill
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