netdev - Re: [PATCH net v3] net: Fix icmp host relookup triggering ip_rt

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Message-ID: <CANn89iLfQVBFp1h17qqiCM7qBAP8cd9APSA+RdR2GEp954wZiA@mail.gmail.com>
Date: Wed, 27 Nov 2024 19:52:02 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: David Ahern <dsahern@...nel.org>
Cc: Dong Chenchen <dongchenchen2@...wei.com>, davem@...emloft.net, pabeni@...hat.com, 
	horms@...nel.org, herbert@...dor.apana.org.au, steffen.klassert@...unet.com, 
	netdev@...r.kernel.org, yuehaibing@...wei.com, zhangchangzhong@...wei.com
Subject: Re: [PATCH net v3] net: Fix icmp host relookup triggering ip_rt_bug

On Wed, Nov 27, 2024 at 4:50 PM David Ahern <dsahern@...nel.org> wrote:
>
> On 11/26/24 9:08 PM, Dong Chenchen wrote:
> > arp link failure may trigger ip_rt_bug while xfrm enabled, call trace is:
> >
> > WARNING: CPU: 0 PID: 0 at net/ipv4/route.c:1241 ip_rt_bug+0x14/0x20
> > Modules linked in:
> > CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc6-00077-g2e1b3cc9d7f7
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> > BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
> > RIP: 0010:ip_rt_bug+0x14/0x20
> > Call Trace:
> >  <IRQ>
> >  ip_send_skb+0x14/0x40
> >  __icmp_send+0x42d/0x6a0
> >  ipv4_link_failure+0xe2/0x1d0
> >  arp_error_report+0x3c/0x50
> >  neigh_invalidate+0x8d/0x100
> >  neigh_timer_handler+0x2e1/0x330
> >  call_timer_fn+0x21/0x120
> >  __run_timer_base.part.0+0x1c9/0x270
> >  run_timer_softirq+0x4c/0x80
> >  handle_softirqs+0xac/0x280
> >  irq_exit_rcu+0x62/0x80
> >  sysvec_apic_timer_interrupt+0x77/0x90
> >
> > The script below reproduces this scenario:
> > ip xfrm policy add src 0.0.0.0/0 dst 0.0.0.0/0 \
> >       dir out priority 0 ptype main flag localok icmp
> > ip l a veth1 type veth
> > ip a a 192.168.141.111/24 dev veth0
> > ip l s veth0 up
> > ping 192.168.141.155 -c 1
> >
> > icmp_route_lookup() create input routes for locally generated packets
> > while xfrm relookup ICMP traffic.Then it will set input route
> > (dst->out = ip_rt_bug) to skb for DESTUNREACH.
> >
> > For ICMP err triggered by locally generated packets, dst->dev of output
> > route is loopback. Generally, xfrm relookup verification is not required
> > on loopback interfaces (net.ipv4.conf.lo.disable_xfrm = 1).
> >
> > Skip icmp relookup for locally generated packets to fix it.
> >
> > Fixes: 8b7817f3a959 ("[IPSEC]: Add ICMP host relookup support")
> > Signed-off-by: Dong Chenchen <dongchenchen2@...wei.com>
> > ---
> > v3: avoid the expensive call to  inet_addr_type_dev_table()
> > and addr_type variable suggested by Eric
> > v2: Skip icmp relookup to fix bug
> > ---
> >  net/ipv4/icmp.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
> > index 4f088fa1c2f2..963a89ae9c26 100644
> > --- a/net/ipv4/icmp.c
> > +++ b/net/ipv4/icmp.c
> > @@ -517,6 +517,9 @@ static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
> >       if (!IS_ERR(dst)) {
> >               if (rt != rt2)
> >                       return rt;
> > +             if (inet_addr_type_dev_table(net, route_lookup_dev,
> > +                                          fl4->daddr) == RTN_LOCAL)
> > +                     return rt;
> >       } else if (PTR_ERR(dst) == -EPERM) {
> >               rt = NULL;
> >       } else {
>
> Reviewed-by: David Ahern <dsahern@...nel.org>

Reviewed-by: Eric Dumazet <edumazet@...gle.com>