[lkml]   [2009]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: RFC: Network privilege separation.
Le lundi 12 janvier 2009 22:14:35 Andi Kleen, vous avez écrit :
> > Expanding the heap,
> That's a problem agreed Ok you can just always use very
> bss arrays sized for the worst case.
> > Getting timestamps.
> At least on 64bit that's done in ring 3 only with a vsyscall.
> > Waiting on futexes,
> > catching signals, polling file descriptors. Seeking, doing vectorized
> > I/O. Cloning.
> That all can be done by the frontend reading/feeding
> data into the pipe. But it shouldn't directly access the user data
> to be immune against attacks.

What's the point of writing a parser (that could also have bugs) when the
kernel can do it? One could argue that shared futexes could be dangerous, but
not the rest?

> > Codecs don't like to read/write raw video through a pipe...
> I don't think that's given. It would need some restructuring,
> but I think the end result would be likely worth it.

A normal DVD would be over 30 megabytes per seconds once decoded, just for the
video. And remember vmsplice() is not allowed by SECCOMP. Media players have
assembly-coded memory copy optimizations (like the kernel) for some reason.

Rémi Denis-Courmont
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2009-01-12 21:19    [W:0.061 / U:0.952 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site