Date: Tue, 14 Aug 2001 11:00:40 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: hackers@freebsd.org Subject: Re: Fwd: error in ip_checkinterface code? Message-ID: <Pine.NEB.3.96L.1010814105749.65192E-100000@fledge.watson.org> In-Reply-To: <20010813143116.A13647@Odin.AC.HMC.Edu>
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Well, the BPF code relies on the ifnet pointer being set or not to determine if a packet is "locally sourced". This permits userland programs to differentiate packets targeted at a local ethernet address but remotely sourced (i.e., looped back) when bridging. "locally sourced" becomes sort of fuzzy in the face of a variety of less traditional packet sources, but is useful. I'd prefer it if non-local packets always had an ifnet defined--could you describe the circumstances where that is not the case in a little more detail? Robert N M Watson FreeBSD Core Team, TrustedBSD Project robert@fledge.watson.org NAI Labs, Safeport Network Services On Mon, 13 Aug 2001, Brooks Davis wrote: > I sent the following to net a while back and got a whole one responce. > Anyone else have any thoughts? Unless someone has a good reason not to, > I'd like to commit the attached patch. > > -- Brooks > > ----- Forwarded message from Brooks Davis <brooks@one-eyed-alien.net> ----- > > From: Brooks Davis <brooks@one-eyed-alien.net> > Date: Mon, 23 Jul 2001 18:44:18 -0700 > To: net@FreeBSD.ORG > Subject: error in ip_checkinterface code? > > I just ran into what appears to be a bug in the ip_checkinterface code. > The problem is that is assumes m->m_pkthdr.rcvif is non-NULL. > Apparently this is normally true, but I have some netgraph code that > processes it's processes in such a way that they lose their interface > pointer which means that when I stick them back into the ip_stack get a > panic. A quick patch that fixes the problem is included below. Is > this fix correct? > > -- Brooks > > Index: ip_input.c > =================================================================== > RCS file: /home/ncvs/src/sys/netinet/ip_input.c,v > retrieving revision 1.174 > diff -u -r1.174 ip_input.c > --- ip_input.c 2001/06/23 17:17:58 1.174 > +++ ip_input.c 2001/07/24 01:46:22 > @@ -559,6 +559,7 @@ > * the packets are received. > */ > checkif = ip_checkinterface && (ipforwarding == 0) && > + m->m_pkthdr.rcvif != NULL && > ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) && > (ip_fw_fwd_addr == NULL); > > -- > Any statement of the form "X is the one, true Y" is FALSE. > PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 > > > > ----- End forwarded message ----- > -- > Any statement of the form "X is the one, true Y" is FALSE. > PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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