netdev - [PATCH net-next] net: ipv4: allocate ipv4_devconf memory for init

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Date:   Sun, 16 Dec 2018 08:15:40 -0800
From:   xiangxia.m.yue@...il.com
To:     netdev@...r.kernel.org
Cc:     Tonghao Zhang <xiangxia.m.yue@...il.com>
Subject: [PATCH net-next] net: ipv4: allocate ipv4_devconf memory for init_net

From: Tonghao Zhang <xiangxia.m.yue@...il.com>

The devconf setting on the init_net will affect other
namespace when them created. For example:

$ cat /proc/sys/net/ipv4/conf/all/rp_filter
0
$ echo 2 > /proc/sys/net/ipv4/conf/all/rp_filter
$ cat /proc/sys/net/ipv4/conf/all/rp_filter
2

$ ip netns add ns100
$ ip netns exec ns100 bash
$ cat /proc/sys/net/ipv4/conf/all/rp_filter
2

The value of rp_filter in the ns100, should be 0 as
default, but it is 2 same as _init_net_.

To fix it and init devconf to default value, we allocate
memory for every namespace(include init_net), this memory
will be used to store themself setting data and we also
allocate memory to register sys_ctl tables.

IPv6 does that in the same way.

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
---
 net/ipv4/devinet.c | 40 ++++++++++++++++------------------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 5b9b6d4..2edf0f8 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2555,33 +2555,28 @@ static __net_init int devinet_init_net(struct net *net)
 	int err;
 	struct ipv4_devconf *all, *dflt;
 #ifdef CONFIG_SYSCTL
-	struct ctl_table *tbl = ctl_forward_entry;
+	struct ctl_table *tbl;
 	struct ctl_table_header *forw_hdr;
 #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)
-			goto err_alloc_all;
+	all = kmemdup(&ipv4_devconf, 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)
+		goto err_alloc_dflt;
 
 #ifdef CONFIG_SYSCTL
-		tbl = kmemdup(tbl, sizeof(ctl_forward_entry), GFP_KERNEL);
-		if (!tbl)
-			goto err_alloc_ctl;
+	tbl = kmemdup(ctl_forward_entry, sizeof(ctl_forward_entry), GFP_KERNEL);
+	if (!tbl)
+		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);
@@ -2610,15 +2605,12 @@ static __net_init int devinet_init_net(struct net *net)
 err_reg_dflt:
 	__devinet_sysctl_unregister(net, all, NETCONFA_IFINDEX_ALL);
 err_reg_all:
-	if (tbl != ctl_forward_entry)
-		kfree(tbl);
+	kfree(tbl);
 err_alloc_ctl:
 #endif
-	if (dflt != &ipv4_devconf_dflt)
-		kfree(dflt);
+	kfree(dflt);
 err_alloc_dflt:
-	if (all != &ipv4_devconf)
-		kfree(all);
+	kfree(all);
 err_alloc_all:
 	return err;
 }
-- 
1.8.3.1