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SubjectRe: ipv4: Use standard iovec primitive in raw_probe_proto_opt
On Thu, Nov 06, 2014 at 04:28:08PM -0500, David Miller wrote:
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Date: Thu, 6 Nov 2014 14:46:29 +0800
>
> > On Thu, Nov 06, 2014 at 06:43:18AM +0000, Al Viro wrote:
> >> On Thu, Nov 06, 2014 at 01:50:23PM +0800, Herbert Xu wrote:
> >> > + /* We only need the first two bytes. */
> >> > + err = memcpy_fromiovecend((void *)&icmph, msg->msg_iov, 0, 2);
> >> > + if (err)
> >> > + return err;
> >> > +
> >> > + fl4->fl4_icmp_type = icmph.type;
> >> > + fl4->fl4_icmp_code = icmph.code;
> >>
> >> That's more readable, but that exposes another problem in there - we read
> >> the same piece of userland data twice, with no promise whatsoever that we'll
> >> get the same value both times...
> >
> > Sure, but you have to be root anyway to write to raw sockets.
> >
> > Patches are welcome :)
>
> I'd agree with this root-only argument maybe 15 years ago, but with
> containers and stuff like that we want to prevent root X from messing
> up the machine for root Y.
>
> This is a recurring topic, and I'd strongly like to avoid adding new
> ways that these kinds of problems can happen.
>
> For example, I'm still on the hook to address the AF_NETLINK mmap TX
> code, which has a similarly abusable issue.

Fair enough. Even though the bug existed prior to my patch I'll
see if we could get rid of it.

Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt


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