On 7/28/19 8:49 PM, Su Yanjun wrote:
> When we send mpls packets and the interface only has a
> manual global ipv6 address, then the two hosts cant communicate.
> I find that in ndisc_send_ns it only tries to get a ll address.
> In my case, the executive path is as below.
> ip6_output
> ->ip6_finish_output
> ->lwtunnel_xmit
> ->mpls_xmit
> ->neigh_resolve_output
> ->neigh_probe
> ->ndisc_solicit
> ->ndisc_send_ns
for the archives, this is not an MPLS problem but a general IPv6
forwarding problem when the egress interface does not have a link local
address.
>
> In RFC4861, 7.2.2 says
> "If the source address of the packet prompting the solicitation is the
> same as one of the addresses assigned to the outgoing interface, that
> address SHOULD be placed in the IP Source Address of the outgoing
> solicitation. Otherwise, any one of the addresses assigned to the
> interface should be used."
>
> In this patch we try get a global address if we get ll address failed.
>
> Signed-off-by: Su Yanjun <suyj.f...@cn.fujitsu.com>
> ---
> include/net/addrconf.h | 4 ++++
> net/ipv6/addrconf.c | 34 ++++++++++++++++++++++++++++++++++
> net/ipv6/ndisc.c | 8 ++++++--
> 3 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> index becdad5..006db8e 100644
> --- a/include/net/addrconf.h
> +++ b/include/net/addrconf.h
> @@ -107,6 +107,10 @@ int __ipv6_get_lladdr(struct inet6_dev *idev, struct
> in6_addr *addr,
> u32 banned_flags);
> int ipv6_get_lladdr(struct net_device *dev, struct in6_addr *addr,
> u32 banned_flags);
> +int __ipv6_get_addr(struct inet6_dev *idev, struct in6_addr *addr,
> + u32 banned_flags);
no reason to export __ipv6_get_addr. I suspect you copied
__ipv6_get_lladdr but it has an external (to addrconf.c) user. In this
case only ipv6_get_addr needs to be exported.
> +int ipv6_get_addr(struct net_device *dev, struct in6_addr *addr,
> + u32 banned_flags);
> bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
> bool match_wildcard);
> bool inet_rcv_saddr_any(const struct sock *sk);
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 521e320..4c0a43f 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -1870,6 +1870,40 @@ int ipv6_get_lladdr(struct net_device *dev, struct
> in6_addr *addr,
> return err;
> }
>
> +int __ipv6_get_addr(struct inet6_dev *idev, struct in6_addr *addr,
> + u32 banned_flags)
> +{
> + struct inet6_ifaddr *ifp;
> + int err = -EADDRNOTAVAIL;
> +
> + list_for_each_entry_reverse(ifp, &idev->addr_list, if_list) {
Addresses are ordered by scope. __ipv6_get_lladdr uses
list_for_each_entry_reverse because the LLA's are after the globals.
Since this is falling back to 'give an address' from this interface, I
think you can just use list_for_each_entry.
> + if (ifp->scope == 0 &&
> + !(ifp->flags & banned_flags)) {
> + *addr = ifp->addr;
> + err = 0;
> + break;
> + }
> + }
> + return err;
> +}
> +
> +int ipv6_get_addr(struct net_device *dev, struct in6_addr *addr,
> + u32 banned_flags)
> +{
> + struct inet6_dev *idev;
> + int err = -EADDRNOTAVAIL;
> +
> + rcu_read_lock();
> + idev = __in6_dev_get(dev);
> + if (idev) {
> + read_lock_bh(&idev->lock);
> + err = __ipv6_get_addr(idev, addr, banned_flags);
> + read_unlock_bh(&idev->lock);
> + }
> + rcu_read_unlock();
> + return err;
> +}
> +
> static int ipv6_count_addresses(const struct inet6_dev *idev)
> {
> const struct inet6_ifaddr *ifp;
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index 083cc1c..18ac2fb 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -606,8 +606,12 @@ void ndisc_send_ns(struct net_device *dev, const struct
> in6_addr *solicit,
>
> if (!saddr) {
And since you are going to do a v2, another nit - define a local banned
flags and use it for both lookups just to make it clear.
u32 banned_flags = IFA_F_TENTATIVE | IFA_F_OPTIMISTIC;
> if (ipv6_get_lladdr(dev, &addr_buf,
> - (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
> - return;
> + (IFA_F_TENTATIVE | IFA_F_OPTIMISTIC))) {
> + /* try global address */
> + if (ipv6_get_addr(dev, &addr_buf,
> + (IFA_F_TENTATIVE | IFA_F_OPTIMISTIC)))
> + return;
> + }
> saddr = &addr_buf;
> }
>
>
