ipv4: net namespace does not inherit network configurations

PATCH zhuyj 2 participants 4 messages Jul 29, 2014 – Oct 13, 2014

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Networking Network drivers IPv4/IPv6

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zhuyj

author

2014-07-29 09:29 UTC #0 lore raw

Hi,all

I did a test on kernel3.16 rc6:

root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
root@qemu1:~# ip netns list
root@qemu1:~# ip netns add fib1
root@qemu1:~# ip netns exec fib1 bash
root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding
0
root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding
1

The behavior of ipv4 and ipv6 is very inconsistent. I checked the kernel source code. I found that from this patch [ipv6: fix bad free of addrconf_init_net], the above difference appeared.

Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So the behavior of ipv4 is not correct.

Based on this patch [ipv6: fix bad free of addrconf_init_net], I made a new patch to fix this problem on ipv4.

Any reply is appreciated.

Zhu Yanjun

Quoted 1 line

From f3a68831d7c58b185d57f30130217b22a8e2c71f Mon Sep 17 00:00:00 2001

From: Zhu Yanjun <[email protected]>
Date: Tue, 29 Jul 2014 17:23:10 +0800
Subject: [PATCH 1/1] ipv4: net namespace does not inherit network
configurations

Ipv4 net namespace requires a similar logic change as commit c900a800 [ipv6: fix bad free of addrconf_init_net] introduces for newer kernels.

Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So a new net namespace should not inherit network configurations from another net namespace including the host.

CC Hong Zhiguo <[email protected]>

CC David S. Miller <[email protected]>

Signed-off-by Zhu Yanjun <[email protected]>

---
 net/ipv4/devinet.c | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

net/ipv4/devinet.c +12 ~~-17~~

index e944937..a16aa39 100644
@@ -2220,28 +2220,23 @@ static __net_init int devinet_init_net(struct net *net)
 #endif
 
 	err = -ENOMEM;
-	all = &ipv4_devconf;
-	dflt = &ipv4_devconf_dflt;
 
-	if (!net_eq(net, &init_net)) {
-		all = kmemdup(all, sizeof(ipv4_devconf), GFP_KERNEL);
-		if (all == NULL)
-			goto err_alloc_all;
-
-		dflt = kmemdup(dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
-		if (dflt == NULL)
-			goto err_alloc_dflt;
+	all = kmemdup(&ipv4_devconf, sizeof(ipv4_devconf), GFP_KERNEL);
+	if (all == NULL)
+		goto err_alloc_all;
 
+	dflt = kmemdup(&ipv4_devconf_dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
+	if (dflt == NULL)
+		goto err_alloc_dflt;
 #ifdef CONFIG_SYSCTL
-		tbl = kmemdup(tbl, sizeof(ctl_forward_entry), GFP_KERNEL);
-		if (tbl == NULL)
-			goto err_alloc_ctl;
+	tbl = kmemdup(tbl, sizeof(ctl_forward_entry), GFP_KERNEL);
+	if (tbl == NULL)
+		goto err_alloc_ctl;
 
-		tbl[0].data = &all->data[IPV4_DEVCONF_FORWARDING - 1];
-		tbl[0].extra1 = all;
-		tbl[0].extra2 = net;
+	tbl[0].data = &all->data[IPV4_DEVCONF_FORWARDING - 1];
+	tbl[0].extra1 = all;
+	tbl[0].extra2 = net;
 #endif
-	}
 
 #ifdef CONFIG_SYSCTL
 	err = __devinet_sysctl_register(net, "all", all);

Signature · 1 line

1.9.1

Cong Wang

2014-07-29 17:48 UTC #1 lore raw

Quoted 14 lines · zhuyj

Hi,all

I did a test on kernel3.16 rc6:

root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
root@qemu1:~# ip netns list
root@qemu1:~# ip netns add fib1
root@qemu1:~# ip netns exec fib1 bash
root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding
0
root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding
1

Quoted 9 lines

The behavior of ipv4 and ipv6 is very inconsistent. I checked the kernel source code. I found that from this patch [ipv6: fix bad free of addrconf_init_net], the above difference appeared.
Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So the behavior of ipv4 is not correct.

Well, they are already independent, not shared, just that the initial value is duplicated from init_net for IPv4.

This change might break existing applications which rely on this behavior, but given IPv6 change is almost the same, I think it's ok.

BTW, you need to submit a patch as normal, instead of as an attachment.

zhuyj

author

2014-07-31 01:59 UTC #2 lore raw

Quoted 24 lines · Cong Wang

Quoted 14 lines · zhuyj
Hi,all
I did a test on kernel3.16 rc6:
root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
root@qemu1:~# ip netns list
root@qemu1:~# ip netns add fib1
root@qemu1:~# ip netns exec fib1 bash
root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding
0
root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding
1
Quoted 9 lines
The behavior of ipv4 and ipv6 is very inconsistent. I checked the kernel source code. I found that from this patch [ipv6: fix bad free of addrconf_init_net], the above difference appeared.
Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So the behavior of ipv4 is not correct.

Quoted 8 lines

Well, they are already independent, not shared, just that the initial value is duplicated from init_net for IPv4.
This change might break existing applications which rely on this behavior, but given IPv6 change is almost the same, I think it's ok.
BTW, you need to submit a patch as normal, instead of as an attachment.

OK. Thanks a lot.

Zhu Yanjun

zhuyj

author

2014-10-13 08:20 UTC #3 lore raw

In reply to Cong Wang

Hi, Miller && Cong

Can we merge this patch into kernel mainline? since the independence between ipv4 and ipv6 is inconsistent even in the latest linux kernel(3.17-rc7), that is, the net namespace is independent in ipv6 while it is not in ipv4.

Thanks a lot.
Zhu Yanjun

Quoted 32 lines · Cong Wang

Quoted 14 lines · zhuyj
Hi,all
I did a test on kernel3.16 rc6:
root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
root@qemu1:~# ip netns list
root@qemu1:~# ip netns add fib1
root@qemu1:~# ip netns exec fib1 bash
root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding
0
root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding
1
Quoted 9 lines
The behavior of ipv4 and ipv6 is very inconsistent. I checked the kernel source code. I found that from this patch [ipv6: fix bad free of addrconf_init_net], the above difference appeared.
Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So the behavior of ipv4 is not correct.
Well, they are already independent, not shared, just that the initial value is duplicated from init_net for IPv4.
This change might break existing applications which rely on this behavior, but given IPv6 change is almost the same, I think it's ok.
BTW, you need to submit a patch as normal, instead of as an attachment.