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Date: Wed, 25 Mar 2009 08:36:03 -0400
From: Vlad Yasevich <vladislav.yasevich@...com>
To: Brian Haley <brian.haley@...com>
CC: davem@...emloft.net, yoshfuji@...ux-ipv6.org, linux@...la.no,
netdev@...r.kernel.org
Subject: Re: [PATCH] IPv6: Add 'autoconf' and 'disable_ipv6' module parameters
Oh, and another issue I just figured out this morning...
Vlad Yasevich wrote:
> Brian Haley wrote:
>> This is the quick and easy 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.all.disable_ipv6=0
>> net.ipv6.conf.lo.disable_ipv6=0
>
> This is kind of confusing. First you say, disable IPv6, then you say enable IPv6, but
> nothing happens. Unless you typo-ed the 'all.disable_ipv6 = 0'...
>
> Also, it looks like if someone decides to switch IPv6 back on for a particular
> interface, they would have to wait until the next RA to get an address. Not an
> optimum solution.
>
>> # 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.
>>
>>
>> ---------------------------------------------------------------
>>
>> 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.
You are letting link-locals to autoconfigure, but did not correctly
finish DAD, because once you set disable_ipv6, ip6_output and ipv6_rcv
will drop all IPv6 packets.
Then later, when you re-enable IPv6, you will not run DAD because the
interface will think that it's already finished.
So there is a possibility of duplicates not being detected.
-vlad
>>
>> The second controls if IPv6 addresses are desired at all. No
>> IPv6 addresses will be added to any interfaces.
>>
>> Signed-off-by: Brian Haley <brian.haley@...com>
>> ---
>> Documentation/networking/ipv6.txt | 37 +++++++++++++++++++++++++++++++++++++
>> include/linux/ipv6.h | 6 ++++++
>> net/ipv6/addrconf.c | 12 +++++++++---
>> net/ipv6/af_inet6.c | 22 +++++++++++++++++-----
>> 4 files changed, 69 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/networking/ipv6.txt b/Documentation/networking/ipv6.txt
>> index 268e5c1..9fd7e21 100644
>> --- a/Documentation/networking/ipv6.txt
>> +++ b/Documentation/networking/ipv6.txt
>> @@ -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.
>> +
>> diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
>> index 476d946..c662efa 100644
>> --- a/include/linux/ipv6.h
>> +++ b/include/linux/ipv6.h
>> @@ -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 */
>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>> index 8499da9..da6f01e 100644
>> --- a/net/ipv6/addrconf.c
>> +++ b/net/ipv6/addrconf.c
>> @@ -1784,6 +1784,7 @@ 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;
>>
>> @@ -1841,7 +1842,7 @@ 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)) {
>> @@ -1874,11 +1875,11 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len)
>>
>> /* Try to figure out our local address for this prefix */
>>
>> - if (pinfo->autoconf && in6_dev->cnf.autoconf) {
>> + if (pinfo->autoconf && in6_dev->cnf.autoconf &&
>> + net->ipv6.devconf_all->autoconf) {
>> 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);
>> @@ -4378,6 +4379,11 @@ 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 */
>> + all->autoconf = dflt->autoconf = ipv6_defaults.autoconf;
>> + all->disable_ipv6 = dflt->disable_ipv6 =
>> + ipv6_defaults.disable_ipv6;
>
> Why set 'all'? Since no interfaces are created yet, setting dflt accomplishes
> what you want.
>
> -vlad
>
>> }
>>
>> net->ipv6.devconf_all = all;
>> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
>> index fbf533c..7278dce 100644
>> --- a/net/ipv6/af_inet6.c
>> +++ b/net/ipv6/af_inet6.c
>> @@ -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)
>> {
>> @@ -1013,7 +1025,7 @@ 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");
>> @@ -1202,7 +1214,7 @@ 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. */
>
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