Date: Sun, 19 Jan 2003 07:30:06 -0800 (PST) From: Hiten Pandya <hiten@unixdaemons.com> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/44361: possible raw socket bug Message-ID: <200301191530.h0JFU6Pm091855@freefall.freebsd.org>
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The following reply was made to PR misc/44361; it has been noted by GNATS.
From: Hiten Pandya <hiten@unixdaemons.com>
To: Kelly Yancey <kbyanc@posi.net>, bug-followup@FreeBSD.ORG
Cc: alfred@FreeBSD.ORG
Subject: Re: misc/44361: possible raw socket bug
Date: Sun, 19 Jan 2003 15:25:50 +0000
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--- Kelly Yancey <kbyanc@posi.net> wrote:
> On Sat, 18 Jan 2003, Alfred Perlstein wrote:
>
> : It appears that we expect the ip_len and ip_off feilds to :
> be sent in host byte order as the stack will fix it to :
> network byte order in ip_output. : : Is this a bug or feature?
> :)
>
> Both, no? :) It's a bug documented in Stevens TCP/IP
> Illustrated 2 as being around since 4.4BSD, but I would expect
> that fixing it would break a good bit. On the other hand, it
> is supposedly fixed in OpenBSD.
We should follow the OpenBSD behaviour [1], which is what the
submitter has told us (using ntohs() for both ip_len, and
ip_off). It was fixed 5 years ago in OpenBSD by deraadt@.
Doing some research shows that NetBSD use HTONS(), because of an
mbuf optimization they made [2] (it was fixed 5 months ago in
their raw_ip.c); I.e. they convert m->m_pkthdr.len to host order
for ip_len, and htons(0) for ip_off:
\begin{verbatim}
/* From: NetBSD src/sys/netinet/raw_ip.c */
ip->ip_off = htons(0);
/* ... */
ip->ip_len = htons(m->m_pkthdr.len);
/* XXX userland passes ip_len and ip_off in host order */
if (m->m_pkthdr.len != ip->ip_len) {
m_freem(m);
return (EINVAL);
}
HTONS(ip->ip_len);
HTONS(ip->ip_off);
\end{verbatim}
For the reference, two Problem Reports were submitted to NetBSD
for this same problem. [3]
I have attached a fix to HEAD with this mail. It should be
MFC'ed, if possible. It is also available from:
http://www.unixdaemons.com/~hiten/work/diffs/netinet+ip_fields-fix.patch
Reference:
[1] - diff(1) rev. 1.8 and 1.9 of OpenBSD raw_ip.c
[2] - diff(1) rev. 1.61 and 1.62 of NetBSD raw_ip.c
[3] - NetBSD PR: 17867 and 10195
Index: sys/netinet/raw_ip.c
===================================================================
RCS file: /home/ncvs/src/sys/netinet/raw_ip.c,v
retrieving revision 1.108
diff -u -r1.108 raw_ip.c
--- sys/netinet/raw_ip.c 2003/01/18 01:10:55 1.108
+++ sys/netinet/raw_ip.c 2003/01/19 15:15:09
@@ -302,6 +302,8 @@
return(EMSGSIZE);
}
ip = mtod(m, struct ip *);
+ ntohs(ip->ip_len);
+ ntohs(ip->ip_off);
/* don't allow both user specified and setsockopt options,
and don't allow packet length sizes that will crash */
if (((ip->ip_hl != (sizeof (*ip) >> 2))
Cheers.
--
Hiten Pandya
http://www.unixdaemons.com/~hiten
hiten@uk.FreeBSD.org, hiten@unixdaemons.com
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Index: sys/netinet/raw_ip.c
===================================================================
RCS file: /home/ncvs/src/sys/netinet/raw_ip.c,v
retrieving revision 1.108
diff -u -r1.108 raw_ip.c
--- sys/netinet/raw_ip.c 2003/01/18 01:10:55 1.108
+++ sys/netinet/raw_ip.c 2003/01/19 15:15:09
@@ -302,6 +302,8 @@
return(EMSGSIZE);
}
ip = mtod(m, struct ip *);
+ ntohs(ip->ip_len);
+ ntohs(ip->ip_off);
/* don't allow both user specified and setsockopt options,
and don't allow packet length sizes that will crash */
if (((ip->ip_hl != (sizeof (*ip) >> 2))
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