Subject: Re: [PATCH 2/2] netns: Add network namespace argument in rt6_fill_node() and ipv6_dev_get_saddr()

From: Daniel Lezcano <[email-masked]>
Date: Sun, 17 Aug 2008 00:47:12 +0200

Brian Haley wrote:
> Add network namespace argument to rt6_fill_node() and
> ipv6_dev_get_saddr().  This required adding a namespace pointer in the
> IPv6 fib dump callback routine.
> 
> -Brian
> 
> Signed-off-by: Brian Haley <[email-masked]>
> ---

This patch is to fix a kernel panic in ipv6_dev_get_saddr.
That happens because the dev parameter can be null and we try to 
dereference dev->nd_net, right ?

The approach looks correct except with the network namespace passed as 
parameter, it must never be NULL.

> diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> index 06b2814..c216de5 100644
> --- a/include/net/addrconf.h
> +++ b/include/net/addrconf.h
> @@ -80,7 +80,8 @@ extern struct inet6_ifaddr      *ipv6_get_ifaddr(struct net *net,
>  						 struct net_device *dev,
>  						 int strict);
> 
> -extern int			ipv6_dev_get_saddr(struct net_device *dev, 
> +extern int			ipv6_dev_get_saddr(struct net *net,
> +					       struct net_device *dev,
>  					       const struct in6_addr *daddr,
>  					       unsigned int srcprefs,
>  					       struct in6_addr *saddr);
> diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
> index bc391ba..5f53db7 100644
> --- a/include/net/ip6_route.h
> +++ b/include/net/ip6_route.h
> @@ -107,6 +107,7 @@ struct rt6_rtnl_dump_arg
>  {
>  	struct sk_buff *skb;
>  	struct netlink_callback *cb;
> +	struct net *net;
>  };
> 
>  extern int rt6_dump_route(struct rt6_info *rt, void *p_arg);
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index a7842c5..dea420a 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -1106,17 +1106,19 @@ out:
>  	return ret;
>  }
> 
> -int ipv6_dev_get_saddr(struct net_device *dst_dev,
> +int ipv6_dev_get_saddr(struct net *net, struct net_device *dst_dev,
>  		       const struct in6_addr *daddr, unsigned int prefs,
>  		       struct in6_addr *saddr)
>  {
>  	struct ipv6_saddr_score scores[2],
>  				*score = &scores[0], *hiscore = &scores[1];
> -	struct net *net = dev_net(dst_dev);
>  	struct ipv6_saddr_dst dst;
>  	struct net_device *dev;
>  	int dst_type;
> 
> +	if (!net)
> +		net = dev_net(dst_dev);

These lines are not needed, because the net parameter will be never 
NULL, see below.

>  	dst_type = __ipv6_addr_type(daddr);
>  	dst.addr = daddr;
>  	dst.ifindex = dst_dev ? dst_dev->ifindex : 0;
> diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
> index 8d05527..f5de3f9 100644
> --- a/net/ipv6/fib6_rules.c
> +++ b/net/ipv6/fib6_rules.c
> @@ -93,7 +93,8 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
>  			if (flags & RT6_LOOKUP_F_SRCPREF_COA)
>  				srcprefs |= IPV6_PREFER_SRC_COA;
> 
> -			if (ipv6_dev_get_saddr(ip6_dst_idev(&rt->u.dst)->dev,
> +			if (ipv6_dev_get_saddr(net,
> +					       ip6_dst_idev(&rt->u.dst)->dev,
>  					       &flp->fl6_dst, srcprefs,
>  					       &saddr))
>  				goto again;
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index 52dddc2..29c7c99 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -378,6 +378,7 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
> 
>  	arg.skb = skb;
>  	arg.cb = cb;
> +	arg.net = net;
>  	w->args = &arg;
> 
>  	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index a4402de..0e844c2 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -934,7 +934,7 @@ static int ip6_dst_lookup_tail(struct sock *sk,
>  		goto out_err_release;
> 
>  	if (ipv6_addr_any(&fl->fl6_src)) {
> -		err = ipv6_dev_get_saddr(ip6_dst_idev(*dst)->dev,
> +		err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
>  					 &fl->fl6_dst,
>  					 sk ? inet6_sk(sk)->srcprefs : 0,
>  					 &fl->fl6_src);
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index beb48e3..f1c62ba 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -549,7 +549,7 @@ static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
>  			override = 0;
>  		in6_ifa_put(ifp);
>  	} else {
> -		if (ipv6_dev_get_saddr(dev, daddr,
> +		if (ipv6_dev_get_saddr(dev_net(dev), dev, daddr,
>  				       inet6_sk(dev_net(dev)->ipv6.ndisc_sk)->srcprefs,
>  				       &tmpaddr))
>  			return;
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 41b165f..9af6115 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -2106,7 +2106,8 @@ static inline size_t rt6_nlmsg_size(void)
>  	       + nla_total_size(sizeof(struct rta_cacheinfo));
>  }
> 
> -static int rt6_fill_node(struct sk_buff *skb, struct rt6_info *rt,
> +static int rt6_fill_node(struct net *net,
> +			 struct sk_buff *skb, struct rt6_info *rt,
>  			 struct in6_addr *dst, struct in6_addr *src,
>  			 int iif, int type, u32 pid, u32 seq,
>  			 int prefix, int nowait, unsigned int flags)
> @@ -2189,7 +2190,7 @@ static int rt6_fill_node(struct sk_buff *skb, struct rt6_info *rt,
>  	} else if (dst) {
>  		struct inet6_dev *idev = ip6_dst_idev(&rt->u.dst);
>  		struct in6_addr saddr_buf;
> -		if (ipv6_dev_get_saddr(idev ? idev->dev : NULL,
> +		if (ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
>  				       dst, 0, &saddr_buf) == 0)
>  			NLA_PUT(skb, RTA_PREFSRC, 16, &saddr_buf);
>  	}
> @@ -2234,7 +2235,8 @@ int rt6_dump_route(struct rt6_info *rt, void *p_arg)
>  	} else
>  		prefix = 0;
> 
> -	return rt6_fill_node(arg->skb, rt, NULL, NULL, 0, RTM_NEWROUTE,
> +	return rt6_fill_node(arg->net,
> +		     arg->skb, rt, NULL, NULL, 0, RTM_NEWROUTE,
>  		     NETLINK_CB(arg->cb->skb).pid, arg->cb->nlh->nlmsg_seq,
>  		     prefix, 0, NLM_F_MULTI);
>  }
> @@ -2300,7 +2302,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr* nlh, void
>  	rt = (struct rt6_info*) ip6_route_output(net, NULL, &fl);
>  	skb->dst = &rt->u.dst;
> 
> -	err = rt6_fill_node(skb, rt, &fl.fl6_dst, &fl.fl6_src, iif,
> +	err = rt6_fill_node(net, skb, rt, &fl.fl6_dst, &fl.fl6_src, iif,
>  			    RTM_NEWROUTE, NETLINK_CB(in_skb).pid,
>  			    nlh->nlmsg_seq, 0, 0, 0);
>  	if (err < 0) {
> @@ -2327,7 +2329,7 @@ void inet6_rt_notify(int event, struct rt6_info *rt, struct nl_info *info)
>  	if (skb == NULL)
>  		goto errout;
> 
> -	err = rt6_fill_node(skb, rt, NULL, NULL, 0,
> +	err = rt6_fill_node(net, skb, rt, NULL, NULL, 0,
>  				event, info->pid, seq, 0, 0, 0);
>  	if (err < 0) {
>  		/* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
> diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
> index 8f1e054..5c36ef2 100644
> --- a/net/ipv6/xfrm6_policy.c
> +++ b/net/ipv6/xfrm6_policy.c
> @@ -57,7 +57,7 @@ static int xfrm6_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
>  	if (IS_ERR(dst))
>  		return -EHOSTUNREACH;
> 
> -	ipv6_dev_get_saddr(ip6_dst_idev(dst)->dev,
> +	ipv6_dev_get_saddr(NULL, ip6_dst_idev(dst)->dev,

	ipv6_dev_get_saddr(&init_net, ...

>  			   (struct in6_addr *)&daddr->a6, 0,
>  			   (struct in6_addr *)&saddr->a6);
>  	dst_release(dst);
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index 483a01d..e0945d4 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -319,7 +319,8 @@ static void sctp_v6_get_saddr(struct sctp_sock *sk,
>  			  __func__, asoc, dst, NIP6(daddr->v6.sin6_addr));
> 
>  	if (!asoc) {
> -		ipv6_dev_get_saddr(dst ? ip6_dst_idev(dst)->dev : NULL,
> +		ipv6_dev_get_saddr(NULL,

		ipv6_dev_get_saddr(&init_net, ...

Using init_net instead of NULL makes sense for xfrm6 and sctp, because 
they are not yet supported by the namespaces :) Furthermore it is more 
practical to track the places where we have to take care of the namespaces.

Thanks.
   -- Daniel