* [PATCH] net: Fix the arp error in some cases
@ 2020-06-17 2:07 guodeqing
2020-06-17 3:10 ` David Ahern
0 siblings, 1 reply; 5+ messages in thread
From: guodeqing @ 2020-06-17 2:07 UTC (permalink / raw)
To: davem; +Cc: kuznet, netdev, dsa, kuba, geffrey.guo
ie.,
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
$ ip rule add from 6.6.6.6 table 6666
$ ip route add 9.9.9.9 via 6.6.6.6
$ ping -I 6.6.6.6 9.9.9.9
PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
3 packets transmitted, 0 received, 100% packet loss, time 2079ms
$ arp
Address HWtype HWaddress Flags Mask Iface
6.6.6.6 (incomplete) eth0
The arp request address is error, this is because fib_table_lookup in
fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of
the fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.
Here I add a check of whether this is RT_TABLE_MAIN to solve this problem.
Fixes: 3bfd847203c6("net: Use passed in table for nexthop lookups")
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
---
net/ipv4/fib_semantics.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e53871e..1f75dc6 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1109,7 +1109,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;
- if (table)
+ if (table && table != RT_TABLE_MAIN)
tbl = fib_get_table(net, table);
if (tbl)
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] net: Fix the arp error in some cases
2020-06-17 2:07 [PATCH] net: Fix the arp error in some cases guodeqing
@ 2020-06-17 3:10 ` David Ahern
2020-06-17 3:38 ` 答复: " Guodeqing (A)
0 siblings, 1 reply; 5+ messages in thread
From: David Ahern @ 2020-06-17 3:10 UTC (permalink / raw)
To: guodeqing, davem; +Cc: kuznet, netdev, dsa, kuba
On 6/16/20 8:07 PM, guodeqing wrote:
> ie.,
> $ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
>
> $ ip rule add from 6.6.6.6 table 6666
>
> $ ip route add 9.9.9.9 via 6.6.6.6
>
> $ ping -I 6.6.6.6 9.9.9.9
> PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
>
> 3 packets transmitted, 0 received, 100% packet loss, time 2079ms
>
> $ arp
> Address HWtype HWaddress Flags Mask Iface
> 6.6.6.6 (incomplete) eth0
>
> The arp request address is error, this is because fib_table_lookup in
> fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of
> the fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.
> Here I add a check of whether this is RT_TABLE_MAIN to solve this problem.
fib_check_nh* is only used when the route is installed into the FIB to
verify the gateway is legit. It is not used when processing arp
requests. Why then, do you believe this fixes something?
^ permalink raw reply [flat|nested] 5+ messages in thread
* 答复: [PATCH] net: Fix the arp error in some cases
2020-06-17 3:10 ` David Ahern
@ 2020-06-17 3:38 ` Guodeqing (A)
2020-06-17 12:44 ` David Ahern
0 siblings, 1 reply; 5+ messages in thread
From: Guodeqing (A) @ 2020-06-17 3:38 UTC (permalink / raw)
To: David Ahern, davem@davemloft.net
Cc: kuznet@ms2.inr.ac.ru, netdev@vger.kernel.org,
dsa@cumulusnetworks.com, kuba@kernel.org
rt_set_nexthop in __mkroute_output will check the nh->nh_scope value to determine whether to use the gw or not.
if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
rt->rt_gateway = nh->nh_gw;
rt->rt_uses_gateway = 1;
}
(ip_route_output_key_hash-> ip_route_output_key_hash_rcu-> __mkroute_output-> rt_set_nexthop)
-----邮件原件-----
发件人: David Ahern [mailto:dsahern@gmail.com]
发送时间: Wednesday, June 17, 2020 11:10
收件人: Guodeqing (A) <geffrey.guo@huawei.com>; davem@davemloft.net
抄送: kuznet@ms2.inr.ac.ru; netdev@vger.kernel.org; dsa@cumulusnetworks.com; kuba@kernel.org
主题: Re: [PATCH] net: Fix the arp error in some cases
On 6/16/20 8:07 PM, guodeqing wrote:
> ie.,
> $ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
>
> $ ip rule add from 6.6.6.6 table 6666
>
> $ ip route add 9.9.9.9 via 6.6.6.6
>
> $ ping -I 6.6.6.6 9.9.9.9
> PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
>
> 3 packets transmitted, 0 received, 100% packet loss, time 2079ms
>
> $ arp
> Address HWtype HWaddress Flags Mask Iface
> 6.6.6.6 (incomplete) eth0
>
> The arp request address is error, this is because fib_table_lookup in
> fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of the
> fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.
> Here I add a check of whether this is RT_TABLE_MAIN to solve this problem.
fib_check_nh* is only used when the route is installed into the FIB to verify the gateway is legit. It is not used when processing arp requests. Why then, do you believe this fixes something?
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: 答复: [PATCH] net: Fix the arp error in some cases
2020-06-17 3:38 ` 答复: " Guodeqing (A)
@ 2020-06-17 12:44 ` David Ahern
0 siblings, 0 replies; 5+ messages in thread
From: David Ahern @ 2020-06-17 12:44 UTC (permalink / raw)
To: Guodeqing (A), davem@davemloft.net
Cc: kuznet@ms2.inr.ac.ru, netdev@vger.kernel.org,
dsa@cumulusnetworks.com, kuba@kernel.org
On 6/16/20 9:38 PM, Guodeqing (A) wrote:
> rt_set_nexthop in __mkroute_output will check the nh->nh_scope value to determine whether to use the gw or not.
> if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
> rt->rt_gateway = nh->nh_gw;
> rt->rt_uses_gateway = 1;
> }
>
> (ip_route_output_key_hash-> ip_route_output_key_hash_rcu-> __mkroute_output-> rt_set_nexthop)
>
ok, I see now. Thanks.
Reviewed-by: David Ahern <dsahern@gmail.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] net: Fix the arp error in some cases
@ 2020-06-13 6:49 guodeqing
2020-06-13 14:31 ` David Ahern
0 siblings, 1 reply; 5+ messages in thread
From: guodeqing @ 2020-06-13 6:49 UTC (permalink / raw)
To: davem; +Cc: kuznet, netdev, dsa, kuba, geffrey.guo
ie.,
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
$ ip rule add from 6.6.6.6 table 6666
$ ip route add 9.9.9.9 via 6.6.6.6
$ ping -I 6.6.6.6 9.9.9.9
PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
^C
--- 9.9.9.9 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2079ms
$ arp
Address HWtype HWaddress Flags Mask Iface
6.6.6.6 (incomplete) eth0
The arp request address is error, this problem can be reproduced easily.
Fixes: 3bfd847203c6("net: Use passed in table for nexthop lookups")
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
---
net/ipv4/fib_semantics.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e53871e..1f75dc6 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1109,7 +1109,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;
- if (table)
+ if (table && table != RT_TABLE_MAIN)
tbl = fib_get_table(net, table);
if (tbl)
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] net: Fix the arp error in some cases
2020-06-13 6:49 guodeqing
@ 2020-06-13 14:31 ` David Ahern
2020-06-15 2:48 ` 答复: " Guodeqing (A)
0 siblings, 1 reply; 5+ messages in thread
From: David Ahern @ 2020-06-13 14:31 UTC (permalink / raw)
To: guodeqing, davem; +Cc: kuznet, netdev, dsa, kuba
On 6/13/20 12:49 AM, guodeqing wrote:
> ie.,
> $ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
>
> $ ip rule add from 6.6.6.6 table 6666
without a default entry in table 6666 the lookup proceeds to the next
table - which by default is the main table.
>
> $ ip route add 9.9.9.9 via 6.6.6.6
>
> $ ping -I 6.6.6.6 9.9.9.9
> PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
>
> ^C
> --- 9.9.9.9 ping statistics ---
> 3 packets transmitted, 0 received, 100% packet loss, time 2079ms
>
> $ arp
> Address HWtype HWaddress Flags Mask Iface
> 6.6.6.6 (incomplete) eth0
>
> The arp request address is error, this problem can be reproduced easily.
>
> Fixes: 3bfd847203c6("net: Use passed in table for nexthop lookups")
> Signed-off-by: guodeqing <geffrey.guo@huawei.com>
> ---
> net/ipv4/fib_semantics.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index e53871e..1f75dc6 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1109,7 +1109,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
> if (fl4.flowi4_scope < RT_SCOPE_LINK)
> fl4.flowi4_scope = RT_SCOPE_LINK;
>
> - if (table)
> + if (table && table != RT_TABLE_MAIN)
> tbl = fib_get_table(net, table);
>
> if (tbl)
>
how does gateway validation when the route is installed affect arp
resolution?
you are missing something in explaining the problem you are seeing.
^ permalink raw reply [flat|nested] 5+ messages in thread* 答复: [PATCH] net: Fix the arp error in some cases
2020-06-13 14:31 ` David Ahern
@ 2020-06-15 2:48 ` Guodeqing (A)
0 siblings, 0 replies; 5+ messages in thread
From: Guodeqing (A) @ 2020-06-15 2:48 UTC (permalink / raw)
To: David Ahern, davem@davemloft.net
Cc: kuznet@ms2.inr.ac.ru, netdev@vger.kernel.org,
dsa@cumulusnetworks.com, kuba@kernel.org
-----邮件原件-----
发件人: David Ahern [mailto:dsahern@gmail.com]
发送时间: Saturday, June 13, 2020 22:32
收件人: Guodeqing (A) <geffrey.guo@huawei.com>; davem@davemloft.net
抄送: kuznet@ms2.inr.ac.ru; netdev@vger.kernel.org; dsa@cumulusnetworks.com; kuba@kernel.org
主题: Re: [PATCH] net: Fix the arp error in some cases
On 6/13/20 12:49 AM, guodeqing wrote:
> ie.,
> $ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
>
> $ ip rule add from 6.6.6.6 table 6666
without a default entry in table 6666 the lookup proceeds to the next table - which by default is the main table.
---yes，if without the rule，this problem will not happen.
Follow the steps:
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0
$ ip route add 9.9.9.9 via 6.6.6.6
$ ping -I 6.6.6.6 9.9.9.9
And The arp request address is 9.9.9.9 and is right.(" gateway can be actually local interface address,
* so that gatewayed route is direct")
>
> $ ip route add 9.9.9.9 via 6.6.6.6
>
> $ ping -I 6.6.6.6 9.9.9.9
> PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.
>
> ^C
> --- 9.9.9.9 ping statistics ---
> 3 packets transmitted, 0 received, 100% packet loss, time 2079ms
>
> $ arp
> Address HWtype HWaddress Flags Mask Iface
> 6.6.6.6 (incomplete) eth0
>
> The arp request address is error, this problem can be reproduced easily.
>
> Fixes: 3bfd847203c6("net: Use passed in table for nexthop lookups")
> Signed-off-by: guodeqing <geffrey.guo@huawei.com>
> ---
> net/ipv4/fib_semantics.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index
> e53871e..1f75dc6 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1109,7 +1109,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
> if (fl4.flowi4_scope < RT_SCOPE_LINK)
> fl4.flowi4_scope = RT_SCOPE_LINK;
>
> - if (table)
> + if (table && table != RT_TABLE_MAIN)
> tbl = fib_get_table(net, table);
>
> if (tbl)
>
how does gateway validation when the route is installed affect arp resolution?
you are missing something in explaining the problem you are seeing.
-- This problem can only happen in some cases,this 3bfd847203c6 patch will do the main table lookup error in some cases, and I think it should not do the main table lookup because the next function fib_lookup does the maintable lookup.
^ permalink raw reply [flat|nested] 5+ messages in thread
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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2020-06-17 2:07 [PATCH] net: Fix the arp error in some cases guodeqing
2020-06-17 3:10 ` David Ahern
2020-06-17 3:38 ` 答复: " Guodeqing (A)
2020-06-17 12:44 ` David Ahern
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2020-06-13 6:49 guodeqing
2020-06-13 14:31 ` David Ahern
2020-06-15 2:48 ` 答复: " Guodeqing (A)
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