IPv6: Add 'autoconf' and 'disable_ipv6' module parameters

This is v2 of the patch to add autoconf and disable_ipv6 module parameters to IPv6. I don't think anything more complicated is needed, assuming you play with the /etc configuration files.

For example, if you wanted to enable IPv6 just on 'lo' you would:

1. Add "ipv6" to /etc/modules (if you don't, step #3 might fail)

2. Add this to /etc/modprobe.conf:

options ipv6 disable_ipv6=1

3. Add these to /etc/sysctl.conf:

	net.ipv6.conf.lo.disable_ipv6=0

# ip -6 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever

The wording can probably be cleaned-up a little in ipv6.txt, comments welcome.

Differences from v1:

1. Changing sysctl value net.ipv6.conf.all.disable_ipv6 toggles the value on all interfaces.

2. Changing the sysctl value "disable_ipv6" for a specific interface will dynamically change the state of the interface. On an enable, it will add a link-local and start DAD. On a disable it will remove all IPv6 addresses. This also happens in #1 above as well.

3. The "all" values for these sysctl's are no longer set on module load to their given values, just the "default" ones.

4. ipv6_prefix_rcv() no longer checks net.ipv6.conf.all.autoconf before deciding to do auto-configuration, just the device-specific value.

---------------------------------------------------------------

Add 'autoconf' and 'disable_ipv6' parameters to the IPv6 module.

The first controls if IPv6 addresses are autoconfigured from prefixes received in Router Advertisements. The IPv6 loopback (::1) and link-local addresses are still configured.

The second controls if IPv6 addresses are desired at all. No IPv6 addresses will be added to any interfaces.

---

b/Documentation/networking/ip-sysctl.txt
index 3ffd233..8be7623 100644

@@ -1057,6 +1057,13 @@ disable_ipv6 - BOOLEAN
 	address.
 	Default: FALSE (enable IPv6 operation)
 
+	When this value is changed from 1 to 0 (IPv6 is being enabled),
+	it will dynamically create a link-local address on the given
+	interface and start Duplicate Address Detection, if necessary.
+
+	When this value is changed from 0 to 1 (IPv6 is being disabled),
+	it will dynamically delete all address on the given interface.
+
 accept_dad - INTEGER
 	Whether to accept DAD (Duplicate Address Detection).
 	0: Disable DAD

index 268e5c1..9fd7e21 100644
@@ -33,3 +33,40 @@ disable
 
 		A reboot is required to enable IPv6.
 
+autoconf
+
+	Specifies whether to enable IPv6 address autoconfiguration
+	on all interfaces.  This might be used when one does not wish
+	for addresses to be automatically generated from prefixes
+	received in Router Advertisements.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 address autoconfiguration is disabled on all interfaces.
+
+		Only the IPv6 loopback address (::1) and link-local addresses
+		will be added to interfaces.
+
+	1
+		IPv6 address autoconfiguration is enabled on all interfaces.
+
+		This is the default value.
+
+disable_ipv6
+
+	Specifies whether to disable IPv6 on all interfaces.
+	This might be used when no IPv6 addresses are desired.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 is enabled on all interfaces.
+
+		This is the default value.
+
+	1
+		IPv6 is disabled on all interfaces.
+
+		No IPv6 addresses will be added to interfaces.
+

index 476d946..c662efa 100644
@@ -169,6 +169,12 @@ struct ipv6_devconf {
 	__s32		accept_dad;
 	void		*sysctl;
 };
+
+struct ipv6_params {
+	__s32 disable_ipv6;
+	__s32 autoconf;
+};
+extern struct ipv6_params ipv6_defaults;
 #endif
 
 /* index values for the variables in ipv6_devconf */

index 31938e5..c348837 100644
@@ -591,7 +591,6 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr

*addr, int pfxlen,
{
struct inet6_ifaddr *ifa = NULL;
struct rt6_info *rt;
- struct net *net = dev_net(idev->dev);
int hash;
int err = 0;
int addr_type = ipv6_addr_type(addr);
@@ -608,7 +607,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
goto out2;
}

- if (idev->cnf.disable_ipv6 || net->ipv6.devconf_all->disable_ipv6) {
+ if (idev->cnf.disable_ipv6) {
err = -EACCES;
goto out2;
}
@@ -1752,6 +1751,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
__u32 prefered_lft;
int addr_type;
struct inet6_dev *in6_dev;
+ struct net *net = dev_net(dev);

pinfo = (struct prefix_info *) opt;

@@ -1809,7 +1809,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
if (addrconf_finite_timeout(rt_expires))
rt_expires *= HZ;

- rt = rt6_lookup(dev_net(dev), &pinfo->prefix, NULL,
+ rt = rt6_lookup(net, &pinfo->prefix, NULL,
dev->ifindex, 1);

if (rt && addrconf_is_prefix_route(rt)) {
@@ -1846,7 +1846,6 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
struct inet6_ifaddr * ifp;
struct in6_addr addr;
int create = 0, update_lft = 0;
- struct net *net = dev_net(dev);

if (pinfo->prefix_len == 64) {
memcpy(&addr, &pinfo->prefix, 8);
@@ -3988,6 +3987,75 @@ static int addrconf_sysctl_forward_strategy(ctl_table *table,
return addrconf_fixup_forwarding(table, valp, val);
}

+static void dev_disable_change(struct inet6_dev *idev)
+{
+ if (!idev || !idev->dev)
+ return;
+
+ if (idev->cnf.disable_ipv6)
+ addrconf_notify(NULL, NETDEV_DOWN, idev->dev);
+ else
+ addrconf_notify(NULL, NETDEV_UP, idev->dev);
+}
+
+static void addrconf_disable_change(struct net *net, __s32 newf) +{
+ struct net_device *dev;
+ struct inet6_dev *idev;
+
+ read_lock(&dev_base_lock);
+ for_each_netdev(net, dev) {
+ rcu_read_lock();
+ idev = __in6_dev_get(dev);
+ if (idev) {
+ int changed = (!idev->cnf.disable_ipv6) ^ (!newf);
+ idev->cnf.disable_ipv6 = newf;
+ if (changed)
+ dev_disable_change(idev);
+ }
+ rcu_read_unlock();
+ }
+ read_unlock(&dev_base_lock);
+}
+
+static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int old) +{
+ struct net *net;
+
+ net = (struct net *)table->extra2;
+
+ if (p == &net->ipv6.devconf_dflt->disable_ipv6)
+ return 0;
+
+ if (!rtnl_trylock())
+ return restart_syscall();
+
+ if (p == &net->ipv6.devconf_all->disable_ipv6) {
+ __s32 newf = net->ipv6.devconf_all->disable_ipv6;
+ net->ipv6.devconf_dflt->disable_ipv6 = newf;
+ addrconf_disable_change(net, newf);
+ } else if ((!*p) ^ (!old))
+ dev_disable_change((struct inet6_dev *)table->extra1);
+
+ rtnl_unlock();
+ return 0;
+}
+
+static
+int addrconf_sysctl_disable(ctl_table *ctl, int write, struct file * filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int *valp = ctl->data;
+ int val = *valp;
+ int ret;
+
+ ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
+
+ if (write)
+ ret = addrconf_disable_ipv6(ctl, valp, val);
+ return ret;
+}
+
static struct addrconf_sysctl_table
{
struct ctl_table_header *sysctl_header;
@@ -4225,7 +4293,8 @@ static struct addrconf_sysctl_table
.data = &ipv6_devconf.disable_ipv6,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = addrconf_sysctl_disable,
+ .strategy = sysctl_intvec,
},
{
.ctl_name = CTL_UNNUMBERED,
@@ -4346,6 +4415,10 @@ static int addrconf_init_net(struct net *net)
dflt = kmemdup(dflt, sizeof(ipv6_devconf_dflt), GFP_KERNEL); if (dflt == NULL)
goto err_alloc_dflt;
+ } else {
+ /* these will be inherited by all namespaces */
+ dflt->autoconf = ipv6_defaults.autoconf;
+ dflt->disable_ipv6 = ipv6_defaults.disable_ipv6;
}

net->ipv6.devconf_all = all;

index b6215be..85b3d00 100644
@@ -72,9 +72,21 @@ MODULE_LICENSE("GPL");
 static struct list_head inetsw6[SOCK_MAX];
 static DEFINE_SPINLOCK(inetsw6_lock);
 
-static int disable_ipv6 = 0;
-module_param_named(disable, disable_ipv6, int, 0);
-MODULE_PARM_DESC(disable, "Disable IPv6 such that it is non-functional");
+struct ipv6_params ipv6_defaults = {
+	.disable_ipv6 = 0,
+	.autoconf = 1,
+};
+
+static int disable_ipv6_mod = 0;
+
+module_param_named(disable, disable_ipv6_mod, int, 0444);
+MODULE_PARM_DESC(disable, "Disable IPv6 module such that it is non-functional");
+
+module_param_named(disable_ipv6, ipv6_defaults.disable_ipv6, int, 0444);
+MODULE_PARM_DESC(disable_ipv6, "Disable IPv6 on all interfaces");
+
+module_param_named(autoconf, ipv6_defaults.autoconf, int, 0444);
+MODULE_PARM_DESC(autoconf, "Enable IPv6 address autoconfiguration on all

interfaces");

static __inline__ struct ipv6_pinfo *inet6_sk_generic(struct sock *sk) {
@@ -1038,7 +1050,7 @@ static int __init inet6_init(void)
for(r = &inetsw6[0]; r < &inetsw6[SOCK_MAX]; ++r)
INIT_LIST_HEAD(r);

- if (disable_ipv6) {
+ if (disable_ipv6_mod) {
printk(KERN_INFO
"IPv6: Loaded, but administratively disabled, " "reboot required to enable\n");
@@ -1227,7 +1239,7 @@ module_init(inet6_init);

static void __exit inet6_exit(void)
{
- if (disable_ipv6)
+ if (disable_ipv6_mod)
return;

/* First of all disallow new sockets creation. */

1.5.4.3

From: Brian Haley <[email protected]>
Date: Fri, 29 May 2009 16:48:49 -0400

Applied, but really it is tiring fixing up all of the corruptions your email client made to this patch.

I've had this problem so many times with you that I've totally lost any hope that you'll be able to submit patches cleanly and thus I'm resigned to just fix them up every time from now on. :-/

Sorry, I'll start sending them to myself first in the future. Just reject it next time and force me to do the work to fix it up as it was my fault.

-Brian

I also had to edit the patch for linebreaks etc :)

Anyways... when I apply the patch and try too compile, I get:

net/ipv6/addrconf.c: In function 'addrconf_disable_ipv6':
net/ipv6/addrconf.c:4029: error: implicit declaration of function 'restart_syscall' make[2]: *** [net/ipv6/addrconf.o] Error 1
make[1]: *** [net/ipv6] Error 2

The relevant line is pointed out (->) below:

----
static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int old)

   {
           struct net *net;
   
           net = (struct net *)table->extra2;
   
           if (p == &net->ipv6.devconf_dflt->disable_ipv6)
                   return 0;
   
           if (!rtnl_trylock())

-> return restart_syscall();

           if (p == &net->ipv6.devconf_all->disable_ipv6) {
                   __s32 newf = net->ipv6.devconf_all->disable_ipv6;
                   net->ipv6.devconf_dflt->disable_ipv6 = newf;
                   addrconf_disable_change(net, newf);
           } else if ((!*p) ^ (!old))
                   dev_disable_change((struct inet6_dev *)table->extra1);
   
           rtnl_unlock();
           return 0;

}
----

For what it's worth, I'm using gcc 4.3.3.

Kolbjørn Barmen
UNINETT Driftsenter

Can you send me your .config? restart_syscall() is called further-up in addrconf_fixup_forwarding() which didn't seem to generate an error. Or can you try Davem's latest net-next-2.6 tree?

Thanks,

-Brian