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

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Message-ID: <20241127040850.1513135-1-dongchenchen2@huawei.com>
Date: Wed, 27 Nov 2024 12:08:50 +0800
From: Dong Chenchen <dongchenchen2@...wei.com>
To: <davem@...emloft.net>, <dsahern@...nel.org>, <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>, Dong Chenchen <dongchenchen2@...wei.com>
Subject: [PATCH net v3] net: Fix icmp host relookup triggering ip_rt_bug

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 {
-- 
2.25.1