Re: [PATCH 1/1] ipv6: RTA_PREFSRC support for ipv6 route source address selection

[Stephen Clark <sclark46@earthlink.net>]

On 04/14/2011 10:49 AM, Daniel Walter wrote:
> On Thu, Apr 14, 2011 at 10:01:09AM -0400, Stephen Clark wrote:
>    
>> On 04/14/2011 03:10 AM, Daniel Walter wrote:
>>      
>>> [ipv6] Add support for RTA_PREFSRC
>>>
>>> This patch allows a user to select the preferred source address
>>> for a specific IPv6-Route. It can be set via a netlink message
>>> setting RTA_PREFSRC to a valid IPv6 address which must be
>>> up on the device the route will be bound to.
>>>
>>>
>>> Signed-off-by: Daniel Walter<dwalter@barracuda.com>
>>> ---
>>> Repost patch, after fixing some warnings pointed out on netdev@
>>> applies clean against current linux-2.6 HEAD
>>>
>>>    include/net/ip6_fib.h   |    2 +
>>>    include/net/ip6_route.h |    7 ++++
>>>    net/ipv6/addrconf.c     |    2 +
>>>    net/ipv6/ip6_output.c   |    8 ++--
>>>    net/ipv6/route.c        |   72 +++++++++++++++++++++++++++++++++++++++++++++--
>>>    5 files changed, 84 insertions(+), 7 deletions(-)
>>>
>>> ---
>>> diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
>>> index bc3cde0..98348d5 100644
>>> --- a/include/net/ip6_fib.h
>>> +++ b/include/net/ip6_fib.h
>>> @@ -42,6 +42,7 @@ struct fib6_config {
>>>
>>>    	struct in6_addr	fc_dst;
>>>    	struct in6_addr	fc_src;
>>> +	struct in6_addr	fc_prefsrc;
>>>    	struct in6_addr	fc_gateway;
>>>
>>>    	unsigned long	fc_expires;
>>> @@ -107,6 +108,7 @@ struct rt6_info {
>>>    	struct rt6key			rt6i_dst ____cacheline_aligned_in_smp;
>>>    	u32				rt6i_flags;
>>>    	struct rt6key			rt6i_src;
>>> +	struct rt6key			rt6i_prefsrc;
>>>    	u32				rt6i_metric;
>>>    	u32				rt6i_peer_genid;
>>>
>>> diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
>>> index c850e5f..86b1cb4 100644
>>> --- a/include/net/ip6_route.h
>>> +++ b/include/net/ip6_route.h
>>> @@ -84,6 +84,12 @@ extern int			ip6_route_add(struct fib6_config *cfg);
>>>    extern int			ip6_ins_rt(struct rt6_info *);
>>>    extern int			ip6_del_rt(struct rt6_info *);
>>>
>>> +extern int			ip6_route_get_saddr(struct net *net,
>>> +						    struct rt6_info *rt,
>>> +						    struct in6_addr *daddr,
>>> +						    unsigned int prefs,
>>> +						    struct in6_addr *saddr);
>>> +
>>>    extern struct rt6_info		*rt6_lookup(struct net *net,
>>>    					    const struct in6_addr *daddr,
>>>    					    const struct in6_addr *saddr,
>>> @@ -141,6 +147,7 @@ struct rt6_rtnl_dump_arg {
>>>    extern int rt6_dump_route(struct rt6_info *rt, void *p_arg);
>>>    extern void rt6_ifdown(struct net *net, struct net_device *dev);
>>>    extern void rt6_mtu_change(struct net_device *dev, unsigned mtu);
>>> +extern void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
>>>
>>>
>>>    /*
>>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>>> index 1493534..129d7e1 100644
>>> --- a/net/ipv6/addrconf.c
>>> +++ b/net/ipv6/addrconf.c
>>> @@ -825,6 +825,8 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
>>>    		dst_release(&rt->dst);
>>>    	}
>>>
>>> +	/* clean up prefsrc entries */
>>> +	rt6_remove_prefsrc(ifp);
>>>    out:
>>>    	in6_ifa_put(ifp);
>>>    }
>>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>>> index 46cf7be..1f4c096 100644
>>> --- a/net/ipv6/ip6_output.c
>>> +++ b/net/ipv6/ip6_output.c
>>> @@ -930,10 +930,10 @@ static int ip6_dst_lookup_tail(struct sock *sk,
>>>    		goto out_err_release;
>>>
>>>    	if (ipv6_addr_any(&fl6->saddr)) {
>>> -		err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
>>> -					&fl6->daddr,
>>> -					 sk ? inet6_sk(sk)->srcprefs : 0,
>>> -					&fl6->saddr);
>>> +		struct rt6_info *rt = (struct rt6_info *) *dst;
>>> +		err = ip6_route_get_saddr(net, rt,&fl6->daddr,
>>> +					  sk ? inet6_sk(sk)->srcprefs : 0,
>>> +					&fl6->saddr);
>>>    		if (err)
>>>    			goto out_err_release;
>>>    	}
>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>> index 843406f..af26cc10 100644
>>> --- a/net/ipv6/route.c
>>> +++ b/net/ipv6/route.c
>>> @@ -1325,6 +1325,16 @@ int ip6_route_add(struct fib6_config *cfg)
>>>    	if (dev == NULL)
>>>    		goto out;
>>>
>>> +	if (!ipv6_addr_any(&cfg->fc_prefsrc)) {
>>> +		if (!ipv6_chk_addr(net,&cfg->fc_prefsrc, dev, 0)) {
>>> +			err = -EINVAL;
>>> +			goto out;
>>> +		}
>>> +		ipv6_addr_copy(&rt->rt6i_prefsrc.addr,&cfg->fc_prefsrc);
>>> +		rt->rt6i_prefsrc.plen = 128;
>>> +	} else
>>> +		rt->rt6i_prefsrc.plen = 0;
>>> +
>>>    	if (cfg->fc_flags&   (RTF_GATEWAY | RTF_NONEXTHOP)) {
>>>    		rt->rt6i_nexthop = __neigh_lookup_errno(&nd_tbl,&rt->rt6i_gateway, dev);
>>>    		if (IS_ERR(rt->rt6i_nexthop)) {
>>> @@ -2037,6 +2047,55 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
>>>    	return rt;
>>>    }
>>>
>>> +int ip6_route_get_saddr(struct net *net,
>>> +			struct rt6_info *rt,
>>> +			struct in6_addr *daddr,
>>> +			unsigned int prefs,
>>> +			struct in6_addr *saddr)
>>> +{
>>> +	struct inet6_dev *idev = ip6_dst_idev((struct dst_entry*)rt);
>>> +	int err = 0;
>>> +	if (rt->rt6i_prefsrc.plen)
>>> +		ipv6_addr_copy(saddr,&rt->rt6i_prefsrc.addr);
>>> +	else
>>> +		err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
>>> +					 daddr, prefs, saddr);
>>> +	return err;
>>> +}
>>> +
>>> +/* remove deleted ip from prefsrc entries */
>>> +struct arg_dev_net_ip {
>>> +	struct net_device *dev;
>>> +	struct net *net;
>>> +	struct in6_addr *addr;
>>> +};
>>> +
>>> +static int fib6_remove_prefsrc(struct rt6_info *rt, void *arg)
>>> +{
>>> +	struct net_device *dev = ((struct arg_dev_net_ip *)arg)->dev;
>>> +	struct net *net = ((struct arg_dev_net_ip *)arg)->net;
>>> +	struct in6_addr *addr = ((struct arg_dev_net_ip *)arg)->addr;
>>> +
>>> +	if (((void *)rt->rt6i_dev == dev || dev == NULL)&&
>>> +	    rt != net->ipv6.ip6_null_entry&&
>>> +	    ipv6_addr_equal(addr,&rt->rt6i_prefsrc.addr)) {
>>> +		/* remove prefsrc entry */
>>> +		rt->rt6i_prefsrc.plen = 0;
>>> +	}
>>> +	return 0;
>>> +}
>>> +
>>> +void rt6_remove_prefsrc(struct inet6_ifaddr *ifp)
>>> +{
>>> +	struct net *net = dev_net(ifp->idev->dev);
>>> +	struct arg_dev_net_ip adni = {
>>> +		.dev = ifp->idev->dev,
>>> +		.net = net,
>>> +		.addr =&ifp->addr,
>>> +	};
>>> +	fib6_clean_all(net, fib6_remove_prefsrc, 0,&adni);
>>> +}
>>> +
>>>    struct arg_dev_net {
>>>    	struct net_device *dev;
>>>    	struct net *net;
>>> @@ -2183,6 +2242,9 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
>>>    		nla_memcpy(&cfg->fc_src, tb[RTA_SRC], plen);
>>>    	}
>>>
>>> +	if (tb[RTA_PREFSRC])
>>> +		nla_memcpy(&cfg->fc_prefsrc, tb[RTA_PREFSRC], 16);
>>> +
>>>    	if (tb[RTA_OIF])
>>>    		cfg->fc_ifindex = nla_get_u32(tb[RTA_OIF]);
>>>
>>> @@ -2325,13 +2387,17 @@ static int rt6_fill_node(struct net *net,
>>>    #endif
>>>    			NLA_PUT_U32(skb, RTA_IIF, iif);
>>>    	} else if (dst) {
>>> -		struct inet6_dev *idev = ip6_dst_idev(&rt->dst);
>>>    		struct in6_addr saddr_buf;
>>> -		if (ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
>>> -				       dst, 0,&saddr_buf) == 0)
>>> +		if (ip6_route_get_saddr(net, rt, dst, 0,&saddr_buf) == 0)
>>>    			NLA_PUT(skb, RTA_PREFSRC, 16,&saddr_buf);
>>>    	}
>>>
>>> +	if (rt->rt6i_prefsrc.plen) {
>>> +		struct in6_addr saddr_buf;
>>> +		ipv6_addr_copy(&saddr_buf,&rt->rt6i_prefsrc.addr);
>>> +		NLA_PUT(skb, RTA_PREFSRC, 16,&saddr_buf);
>>> +	}
>>> +
>>>    	if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst))<   0)
>>>    		goto nla_put_failure;
>>>        
>> What userspace application will be used to set this?
>>      
> iproute2 already has support for this, since it is using
> RTA_PREFSRC for ipv4.
>
> ip -6 r a 2001:db8:a::/64 via 2001:db8:b::1 src 2001:db8:b::2
>
>    
Fantastic!

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