[linux-yocto] [PATCH v2] ipv4: net namespace does not inherit network configurations

[zhe.he at windriver.com]

From: He Zhe <zhe.he at windriver.com>

patch from https://lkml.org/lkml/2014/7/29/119

Ipv4 net namespace requires a similar logic change as commit a79ca223e029
[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 <honkiko at gmail.com>
CC: David S. Miller <davem at davemloft.net>
Signed-off-by: Zhu Yanjun <zyjzyj2000 at gmail.com>
Signed-off-by: yzhu1 <yanjun.zhu at windriver.com>

The patch was submitted upstream (https://lkml.org/lkml/2014/7/29/119), but
did not get any significant discussion and was not rejected, and also was
not merged. It still makes sense for Yocto linux kernel.

Signed-off-by: He Zhe <zhe.he at windriver.com>
---
v2: Add summary about the status of the patch

This is for linux-yocto-dev, linux-yocto master and 4.18 branches.

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

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index a34602a..8df4a72 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2560,28 +2560,23 @@ static __net_init int devinet_init_net(struct net *net)
 #endif
 
 	err = -ENOMEM;
-	all = &ipv4_devconf;
-	dflt = &ipv4_devconf_dflt;
+	all = kmemdup(&ipv4_devconf, sizeof(ipv4_devconf), GFP_KERNEL);
+	if (all == NULL)
+		goto err_alloc_all;
 
-	if (!net_eq(net, &init_net)) {
-		all = kmemdup(all, sizeof(ipv4_devconf), GFP_KERNEL);
-		if (!all)
-			goto err_alloc_all;
-
-		dflt = kmemdup(dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
-		if (!dflt)
-			goto err_alloc_dflt;
+	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)
-			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", NETCONFA_IFINDEX_ALL, all);
-- 
2.7.4