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

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Message-ID: <40d6550a-3246-490a-87ac-1f8e3eba3d98@kernel.org>
Date: Wed, 27 Nov 2024 08:50:32 -0700
From: David Ahern <dsahern@...nel.org>
To: Dong Chenchen <dongchenchen2@...wei.com>, davem@...emloft.net,
 edumazet@...gle.com, pabeni@...hat.com, horms@...nel.org,
 herbert@...dor.apana.org.au, steffen.klassert@...unet.com
Cc: 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 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>