[PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[Lu Wei]

In function rt6_nlmsg_size(), the length of nexthop is calculated
by multipling the nexthop length of fib6_info and the number of
siblings. However if the fib6_info has no lwtunnel but the siblings
have lwtunnels, the nexthop length is less than it should be, and
it will trigger a warning in inet6_rt_notify() as follows:

WARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130
......
Call Trace:
 <TASK>
 fib6_add_rt2node+0x685/0xa30
 fib6_add+0x96/0x1b0
 ip6_route_add+0x50/0xd0
 inet6_rtm_newroute+0x97/0xa0
 rtnetlink_rcv_msg+0x156/0x3d0
 netlink_rcv_skb+0x5a/0x110
 netlink_unicast+0x246/0x350
 netlink_sendmsg+0x250/0x4c0
 sock_sendmsg+0x66/0x70
 ___sys_sendmsg+0x7c/0xd0
 __sys_sendmsg+0x5d/0xb0
 do_syscall_64+0x3f/0x90
 entry_SYSCALL_64_after_hwframe+0x72/0xdc

This bug can be reproduced by script:

ip -6 addr add 2002::2/64 dev ens2
ip -6 route add 100::/64 via 2002::1 dev ens2 metric 100

for i in 10 20 30 40 50 60 70;
do
	ip link add link ens2 name ipv_$i type ipvlan
	ip -6 addr add 2002::$i/64 dev ipv_$i
	ifconfig ipv_$i up
done

for i in 10 20 30 40 50 60;
do
	ip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1
dev ipv_$i metric 100
done

ip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100

This patch fixes it by adding nexthop_len of every siblings using
rt6_nh_nlmsg_size().

Fixes: beb1afac518d ("net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute")
Signed-off-by: Lu Wei <luwei32@huawei.com>
---
 net/ipv6/route.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e74e0361fd92..a6983a13dd20 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5540,16 +5540,17 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
 		nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size,
 					 &nexthop_len);
 	} else {
+		struct fib6_info *sibling, *next_sibling;
 		struct fib6_nh *nh = f6i->fib6_nh;
 
 		nexthop_len = 0;
 		if (f6i->fib6_nsiblings) {
-			nexthop_len = nla_total_size(0)	 /* RTA_MULTIPATH */
-				    + NLA_ALIGN(sizeof(struct rtnexthop))
-				    + nla_total_size(16) /* RTA_GATEWAY */
-				    + lwtunnel_get_encap_size(nh->fib_nh_lws);
+			rt6_nh_nlmsg_size(nh, &nexthop_len);
 
-			nexthop_len *= f6i->fib6_nsiblings;
+			list_for_each_entry_safe(sibling, next_sibling,
+						 &f6i->fib6_siblings, fib6_siblings) {
+				rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len);
+			}
 		}
 		nexthop_len += lwtunnel_get_encap_size(nh->fib_nh_lws);
 	}
-- 
2.31.1

Re: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[David Ahern]

On 2/14/23 2:29 AM, Lu Wei wrote:
> In function rt6_nlmsg_size(), the length of nexthop is calculated
> by multipling the nexthop length of fib6_info and the number of
> siblings. However if the fib6_info has no lwtunnel but the siblings
> have lwtunnels, the nexthop length is less than it should be, and
> it will trigger a warning in inet6_rt_notify() as follows:
> 
> WARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130
> ......
> Call Trace:
>  <TASK>
>  fib6_add_rt2node+0x685/0xa30
>  fib6_add+0x96/0x1b0
>  ip6_route_add+0x50/0xd0
>  inet6_rtm_newroute+0x97/0xa0
>  rtnetlink_rcv_msg+0x156/0x3d0
>  netlink_rcv_skb+0x5a/0x110
>  netlink_unicast+0x246/0x350
>  netlink_sendmsg+0x250/0x4c0
>  sock_sendmsg+0x66/0x70
>  ___sys_sendmsg+0x7c/0xd0
>  __sys_sendmsg+0x5d/0xb0
>  do_syscall_64+0x3f/0x90
>  entry_SYSCALL_64_after_hwframe+0x72/0xdc
> 
> This bug can be reproduced by script:
> 
> ip -6 addr add 2002::2/64 dev ens2
> ip -6 route add 100::/64 via 2002::1 dev ens2 metric 100
> 
> for i in 10 20 30 40 50 60 70;
> do
> 	ip link add link ens2 name ipv_$i type ipvlan
> 	ip -6 addr add 2002::$i/64 dev ipv_$i
> 	ifconfig ipv_$i up
> done
> 
> for i in 10 20 30 40 50 60;
> do
> 	ip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1
> dev ipv_$i metric 100
> done
> 
> ip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100

would be good to add that test to
   tools/testing/selftests/net/fib_tests.sh

along with a similar one for IPv4.

> 
> This patch fixes it by adding nexthop_len of every siblings using
> rt6_nh_nlmsg_size().
> 
> Fixes: beb1afac518d ("net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute")
> Signed-off-by: Lu Wei <luwei32@huawei.com>
> ---
>  net/ipv6/route.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[Alexander Lobakin]

From: Lu Wei <luwei32@huawei.com>
Date: Tue, 14 Feb 2023 17:29:33 +0800

> In function rt6_nlmsg_size(), the length of nexthop is calculated
> by multipling the nexthop length of fib6_info and the number of
> siblings. However if the fib6_info has no lwtunnel but the siblings
> have lwtunnels, the nexthop length is less than it should be, and
> it will trigger a warning in inet6_rt_notify() as follows:

[...]

> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index e74e0361fd92..a6983a13dd20 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -5540,16 +5540,17 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
>  		nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size,
>  					 &nexthop_len);
>  	} else {
> +		struct fib6_info *sibling, *next_sibling;
>  		struct fib6_nh *nh = f6i->fib6_nh;
>  
>  		nexthop_len = 0;
>  		if (f6i->fib6_nsiblings) {
> -			nexthop_len = nla_total_size(0)	 /* RTA_MULTIPATH */
> -				    + NLA_ALIGN(sizeof(struct rtnexthop))
> -				    + nla_total_size(16) /* RTA_GATEWAY */
> -				    + lwtunnel_get_encap_size(nh->fib_nh_lws);
> +			rt6_nh_nlmsg_size(nh, &nexthop_len);
>  
> -			nexthop_len *= f6i->fib6_nsiblings;
> +			list_for_each_entry_safe(sibling, next_sibling,
> +						 &f6i->fib6_siblings, fib6_siblings) {
> +				rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len);
> +			}

Just a random nitpick that you shouldn't put braces {} around oneliners :D

>  		}
>  		nexthop_len += lwtunnel_get_encap_size(nh->fib_nh_lws);
>  	}
Thanks,
Olek

Re: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[David Ahern]

On 2/14/23 10:39 AM, Alexander Lobakin wrote:
>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>> index e74e0361fd92..a6983a13dd20 100644
>> --- a/net/ipv6/route.c
>> +++ b/net/ipv6/route.c
>> @@ -5540,16 +5540,17 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
>>  		nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size,
>>  					 &nexthop_len);
>>  	} else {
>> +		struct fib6_info *sibling, *next_sibling;
>>  		struct fib6_nh *nh = f6i->fib6_nh;
>>  
>>  		nexthop_len = 0;
>>  		if (f6i->fib6_nsiblings) {
>> -			nexthop_len = nla_total_size(0)	 /* RTA_MULTIPATH */
>> -				    + NLA_ALIGN(sizeof(struct rtnexthop))
>> -				    + nla_total_size(16) /* RTA_GATEWAY */
>> -				    + lwtunnel_get_encap_size(nh->fib_nh_lws);
>> +			rt6_nh_nlmsg_size(nh, &nexthop_len);
>>  
>> -			nexthop_len *= f6i->fib6_nsiblings;
>> +			list_for_each_entry_safe(sibling, next_sibling,
>> +						 &f6i->fib6_siblings, fib6_siblings) {
>> +				rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len);
>> +			}
> 
> Just a random nitpick that you shouldn't put braces {} around oneliners :D
> 

I believe there can be exceptions and braces make multiple lines like
that more readable.

Re: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[luwei (O)]

ok, I will send v2 version

在 2023/2/14 11:45 PM, David Ahern 写道:
> On 2/14/23 2:29 AM, Lu Wei wrote:
>> In function rt6_nlmsg_size(), the length of nexthop is calculated
>> by multipling the nexthop length of fib6_info and the number of
>> siblings. However if the fib6_info has no lwtunnel but the siblings
>> have lwtunnels, the nexthop length is less than it should be, and
>> it will trigger a warning in inet6_rt_notify() as follows:
>>
>> WARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130
>> ......
>> Call Trace:
>>   <TASK>
>>   fib6_add_rt2node+0x685/0xa30
>>   fib6_add+0x96/0x1b0
>>   ip6_route_add+0x50/0xd0
>>   inet6_rtm_newroute+0x97/0xa0
>>   rtnetlink_rcv_msg+0x156/0x3d0
>>   netlink_rcv_skb+0x5a/0x110
>>   netlink_unicast+0x246/0x350
>>   netlink_sendmsg+0x250/0x4c0
>>   sock_sendmsg+0x66/0x70
>>   ___sys_sendmsg+0x7c/0xd0
>>   __sys_sendmsg+0x5d/0xb0
>>   do_syscall_64+0x3f/0x90
>>   entry_SYSCALL_64_after_hwframe+0x72/0xdc
>>
>> This bug can be reproduced by script:
>>
>> ip -6 addr add 2002::2/64 dev ens2
>> ip -6 route add 100::/64 via 2002::1 dev ens2 metric 100
>>
>> for i in 10 20 30 40 50 60 70;
>> do
>> 	ip link add link ens2 name ipv_$i type ipvlan
>> 	ip -6 addr add 2002::$i/64 dev ipv_$i
>> 	ifconfig ipv_$i up
>> done
>>
>> for i in 10 20 30 40 50 60;
>> do
>> 	ip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1
>> dev ipv_$i metric 100
>> done
>>
>> ip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100
> would be good to add that test to
>     tools/testing/selftests/net/fib_tests.sh
>
> along with a similar one for IPv4.
>
>> This patch fixes it by adding nexthop_len of every siblings using
>> rt6_nh_nlmsg_size().
>>
>> Fixes: beb1afac518d ("net: ipv6: Add support to dump multipath routes via RTA_MULTIPATH attribute")
>> Signed-off-by: Lu Wei <luwei32@huawei.com>
>> ---
>>   net/ipv6/route.c | 11 ++++++-----
>>   1 file changed, 6 insertions(+), 5 deletions(-)
>>
> Reviewed-by: David Ahern <dsahern@kernel.org>
>
>
> .

-- 
Best Regards,
Lu Wei

Re: [PATCH net] ipv6: Add lwtunnel encap size of all siblings in nexthop calculation

[Alexander Lobakin]

From: David Ahern <dsahern@kernel.org>
Date: Tue, 14 Feb 2023 11:11:04 -0700

> On 2/14/23 10:39 AM, Alexander Lobakin wrote:
>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>> index e74e0361fd92..a6983a13dd20 100644
>>> --- a/net/ipv6/route.c
>>> +++ b/net/ipv6/route.c
>>> @@ -5540,16 +5540,17 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
>>>  		nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size,
>>>  					 &nexthop_len);
>>>  	} else {
>>> +		struct fib6_info *sibling, *next_sibling;
>>>  		struct fib6_nh *nh = f6i->fib6_nh;
>>>  
>>>  		nexthop_len = 0;
>>>  		if (f6i->fib6_nsiblings) {
>>> -			nexthop_len = nla_total_size(0)	 /* RTA_MULTIPATH */
>>> -				    + NLA_ALIGN(sizeof(struct rtnexthop))
>>> -				    + nla_total_size(16) /* RTA_GATEWAY */
>>> -				    + lwtunnel_get_encap_size(nh->fib_nh_lws);
>>> +			rt6_nh_nlmsg_size(nh, &nexthop_len);
>>>  
>>> -			nexthop_len *= f6i->fib6_nsiblings;
>>> +			list_for_each_entry_safe(sibling, next_sibling,
>>> +						 &f6i->fib6_siblings, fib6_siblings) {
>>> +				rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len);
>>> +			}
>>
>> Just a random nitpick that you shouldn't put braces {} around oneliners :D
>>
> 
> I believe there can be exceptions and braces make multiple lines like
> that more readable.

Hmm, you know, agree for this one, that for-loop line break changes
things a bit.

Thanks,
Olek