Hi,
2020年8月9日(日) 19:52 Xin Long <lucien....@gmail.com>:
>
> On Fri, Aug 7, 2020 at 5:26 PM Hideaki Yoshifuji
> <hideaki.yoshif...@miraclelinux.com> wrote:
> >
> > Hi,
> >
> > 2020年8月6日(木) 23:03 David Ahern <dsah...@gmail.com>:
> > >
> > > On 8/6/20 2:55 AM, Xin Long wrote:
> > > > On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
> > > > <hideaki.yoshif...@miraclelinux.com> wrote:
> > > >>
> > > >> Hi,
> > > >>
> > > >> 2020年8月4日(火) 0:35 Xin Long <lucien....@gmail.com>:
> > > >>>
> > > >>> This is to add an ip_dev_find like function for ipv6, used to find
> > > >>> the dev by saddr.
> > > >>>
> > > >>> It will be used by TIPC protocol. So also export it.
> > > >>>
> > > >>> Signed-off-by: Xin Long <lucien....@gmail.com>
> > > >>> ---
> > > >>> include/net/addrconf.h | 2 ++
> > > >>> net/ipv6/addrconf.c | 39 +++++++++++++++++++++++++++++++++++++++
> > > >>> 2 files changed, 41 insertions(+)
> > > >>>
> > > >>> diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> > > >>> index 8418b7d..ba3f6c15 100644
> > > >>> --- a/include/net/addrconf.h
> > > >>> +++ b/include/net/addrconf.h
> > > >>> @@ -97,6 +97,8 @@ bool ipv6_chk_custom_prefix(const struct in6_addr
> > > >>> *addr,
> > > >>>
> > > >>> int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device
> > > >>> *dev);
> > > >>>
> > > >>> +struct net_device *ipv6_dev_find(struct net *net, const struct
> > > >>> in6_addr *addr);
> > > >>> +
> > > >>
> > > >> How do we handle link-local addresses?
> > > > This is what "if (!result)" branch meant to do:
> > > >
> > > > + if (!result) {
> > > > + struct rt6_info *rt;
> > > > +
> > > > + rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
> > > > + if (rt) {
> > > > + dev = rt->dst.dev;
> > > > + ip6_rt_put(rt);
> > > > + }
> > > > + } else {
> > > > + dev = result->idev->dev;
> > > > + }
> > > >
> > >
> > > the stated purpose of this function is to find the netdevice to which an
> > > address is attached. A route lookup should not be needed. Walking the
> > > address hash list finds the address and hence the netdev or it does not.
> > >
> > >
> >
> > User supplied scope id which should be set for link-local addresses
> > in TIPC_NLA_UDP_LOCAL attribute must be honored when we
> > check the address.
> Hi, Hideaki san,
>
> Sorry for not understanding your comment earlier.
>
> The bad thing is tipc in iproute2 doesn't seem able to set scope_id.
I looked into the iproute2 code quickly and I think it should; it uses
getaddrinfo(3) and it will fill if you say "fe80::1%eth0" or something
like that.... OR, fix the bug.
> I saw many places in kernel doing this check:
>
> if (__ipv6_addr_needs_scope_id(atype) &&
> !ip6->sin6_scope_id) { return -EINVAL; }
>
> Can I ask why scope id is needed for link-local addresses?
> and is that for link-local addresses only?
Because we distinguish link-local scope addresses on different interfaces.
On the other hand, we do not distinguish global scope addresses on
different interfaces.
>
> >
> > ipv6_chk_addr() can check if the address and supplied ifindex is a valid
> > local address. Or introduce an extra ifindex argument to ipv6_dev_find().
> Yeah, but if scope id means ifindex for link-local addresses, ipv6_dev_find()
> would be more like a function to validate the address with right scope id.
>
I think we should find a net_device with a specific "valid" (non-tentative)
address here, and your initial implementation is not enough because it does
not reject tentative addresses. I'd recommend using generic ipv6_chk_addr()
inside.
> Thanks for your reviewing.
