Re: kern/52077: "route add" installs unreachable gateway

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

The following reply was made to PR kern/52077; it has been noted by GNATS.

From: Ryota Ozaki <ozaki-r%netbsd.org@localhost>
To: s-yamaguchi%iij.ad.jp@localhost
Cc: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>, kern-bug-people%netbsd.org@localhost, 
	gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/52077: "route add" installs unreachable gateway
Date: Wed, 22 Mar 2017 16:35:25 +0900

 On Wed, Mar 15, 2017 at 6:05 PM,  <s-yamaguchi%iij.ad.jp@localhost> wrote:
 >>Number:         52077
 >>Category:       kern
 >>Synopsis:       "route add" installs unreachable gateway
 >>Confidential:   no
 >>Severity:       non-critical
 >>Priority:       low
 >>Responsible:    kern-bug-people
 >>State:          open
 >>Class:          sw-bug
 >>Submitter-Id:   net
 >>Arrival-Date:   Wed Mar 15 09:05:00 +0000 2017
 >>Originator:     Shoichi Yamaguchi
 >>Release:        -current
 >>Organization:
 > Internet Initiative Japan Inc.
 >>Environment:
 > NetBSD netbsd 7.99.66 NetBSD 7.99.66 (GENERIC) #4: Wed Mar 15 15:04:08 JST 2017  root@deskfd:(hidden) amd64
 >>Description:
 > the "route add" command install wrong route whose gateway is unreachable if the destination is reachable. And the route whose gateway is directly connected cannot be installed.
 > I do not know whether this is bug, or not. But, OpenBSD fixed this behavior at the following commit.And, FreeBSD is same behavior as OpenBSD too
 >  - https://bitbucket.org/braindamaged/openbsd-src/commits/097d8d9ded40b4c7832d2e7e486a7876832445fc
 >
 >>How-To-Repeat:
 > netbsd# route show -inet
 > Routing tables
 >
 > Internet:
 > Destination        Gateway            Flags    Refs      Use    Mtu Interface
 > default            192.168.95.1       UG          -        -      -  wm1
 > 127/8              localhost          UGR         -        -  33624  lo0
 > localhost          lo0                UHl         -        -  33624  lo0
 > 192.168.56/24      link#2             U           -        -      -  wm0
 > 192.168.56.68      link#2             UHl         -        -      -  lo0
 > 192.168.95/24      link#3             U           -        -      -  wm1
 > 192.168.95.105     link#3             UHl         -        -      -  lo0
 > netbsd# route add -net 192.168.56.192/26 10.0.0.1
 > add net 192.168.56.192: gateway 10.0.0.1
 > netbsd# route show -inet
 > Routing tables
 >
 > Internet:
 > Destination        Gateway            Flags    Refs      Use    Mtu Interface
 > default            192.168.95.1       UG          -        -      -  wm1
 > 127/8              localhost          UGR         -        -  33624  lo0
 > localhost          lo0                UHl         -        -  33624  lo0
 > 192.168.56/24      link#2             U           -        -      -  wm0
 > 192.168.56.68      link#2             UHl         -        -      -  lo0
 > 192.168.56.192/26  10.0.0.1           UG          -        -      -  wm0
 > 192.168.95/24      link#3             U           -        -      -  wm1
 > 192.168.95.105     link#3             UHl         -        -      -  lo0
 > netbsd# route get 192.168.56.193
 >    route to: 192.168.56.193
 > destination: 192.168.56.192
 >        mask: 255.255.255.192
 >     gateway: 10.0.0.1
 >  local addr: 192.168.56.68
 >   interface: wm0
 >       flags: <UP,GATEWAY,DONE,STATIC>
 >  recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
 >        0         0         0         0         0         0         0         0
 >>Fix:
 > diff --git a/sys/net/route.c b/sys/net/route.c
 > index 1411f54..c99fc6e 100644
 > --- a/sys/net/route.c
 > +++ b/sys/net/route.c
 > @@ -1026,11 +1026,15 @@ ifa_ifwithroute_psref(int flags, const struct sockaddr *dst,
 >
 >                 /* XXX we cannot call rtalloc1 if holding the rt lock */
 >                 if (RT_LOCKED())
 > -                       rt = rtalloc1_locked(dst, 0, true);
 > +                       rt = rtalloc1_locked(gateway, 0, true);
 >                 else
 > -                       rt = rtalloc1(dst, 0);
 > +                       rt = rtalloc1(gateway, 0);
 >                 if (rt == NULL)
 >                         return NULL;
 > +               if (rt->rt_flags & RTF_GATEWAY) {
 > +                       rt_unref(rt);
 > +                       return NULL;
 > +               }
 >                 /*
 >                  * Just in case. May not need to do this workaround.
 >                  * Revisit when working on rtentry MP-ification.
 >
 >
 > ----------------------------------------------------------------
 > Added the RTF_GATEWAY check by looking at the following commit:
 >  - https://bitbucket.org/braindamaged/openbsd-src/commits/78ba7cb9777cd1540f703219bd6463521f1f138b
 >
 
 The patch breaks an ATF test, t_route#route_default_reject;
 "route change -inet6 default -reject" in the test begins failing.
 
 It seems that we need to skip route checks if a gateway isn't specified,
 which exist in FreeBSD and OpenBSD: http://www.netbsd.org/~ozaki-r/pr52077.diff
 
   ozaki-r