[PATCH net 0/2] net: fix a mcast issue for tipc udp media

Patch 1 is to add a function to get the dev by source address,
whcih will be used by Patch 2.

Xin Long (2):
  ipv6: add ipv6_dev_find()
  tipc: set ub->ifindex for local ipv6 address

 include/net/addrconf.h |  2 ++
 net/ipv6/addrconf.c    | 39 +++++++++++++++++++++++++++++++++++++++
 net/tipc/udp_media.c   |  8 ++++++++
 3 files changed, 49 insertions(+)

-- 
2.1.0

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.xin@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);
+
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
 				     const struct in6_addr *addr,
 				     struct net_device *dev, int strict);

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 840bfdb..857d6f9 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -1983,6 +1983,45 @@ int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
 }
 EXPORT_SYMBOL(ipv6_chk_prefix);
 
+/**
+ * ipv6_dev_find - find the first device with a given source address.
+ * @net: the net namespace
+ * @addr: the source address
+ *
+ * The caller should be protected by RCU, or RTNL.
+ */
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
+{
+	unsigned int hash = inet6_addr_hash(net, addr);
+	struct inet6_ifaddr *ifp, *result = NULL;
+	struct net_device *dev = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
+		if (net_eq(dev_net(ifp->idev->dev), net) &&
+		    ipv6_addr_equal(&ifp->addr, addr)) {
+			result = ifp;
+			break;
+		}
+	}
+
+	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;
+	}
+	rcu_read_unlock();
+
+	return dev;
+}
+EXPORT_SYMBOL(ipv6_dev_find);
+
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
 				     struct net_device *dev, int strict)
 {

-- 
2.1.0

Without ub->ifindex set for ipv6 address in tipc_udp_enable(),
ipv6_sock_mc_join() may make the wrong dev join the multicast
address in enable_mcast(). This causes that tipc links would
never be created.

So fix it by getting the right netdev and setting ub->ifindex,
as it does for ipv4 address.

Reported-by: Shuang Li <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/tipc/udp_media.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index 28a283f..9dec596 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c

@@ -738,6 +738,13 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 		b->mtu = b->media->mtu;
 #if IS_ENABLED(CONFIG_IPV6)
 	} else if (local.proto == htons(ETH_P_IPV6)) {
+		struct net_device *dev;
+
+		dev = ipv6_dev_find(net, &local.ipv6);
+		if (!dev) {
+			err = -ENODEV;
+			goto err;
+		}
 		udp_conf.family = AF_INET6;
 		udp_conf.use_udp6_tx_checksums = true;
 		udp_conf.use_udp6_rx_checksums = true;

@@ -745,6 +752,7 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 			udp_conf.local_ip6 = in6addr_any;
 		else
 			udp_conf.local_ip6 = local.ipv6;
+		ub->ifindex = dev->ifindex;
 		b->mtu = 1280;
 #endif
 	} else {

-- 
2.1.0

On 8/3/20 11:34 PM, Xin Long wrote:

Without ub->ifindex set for ipv6 address in tipc_udp_enable(),
ipv6_sock_mc_join() may make the wrong dev join the multicast
address in enable_mcast(). This causes that tipc links would
never be created.

So fix it by getting the right netdev and setting ub->ifindex,
as it does for ipv4 address.

Reported-by: Shuang Li <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>

Acked-by: Ying Xue <redacted>

On 8/3/20 11:34 PM, Xin Long wrote:

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.xin@gmail.com>

Acked-by: Ying Xue <redacted>

From: Xin Long <lucien.xin@gmail.com>
Date: Mon,  3 Aug 2020 23:34:45 +0800

Patch 1 is to add a function to get the dev by source address,
whcih will be used by Patch 2.

Series applied, thank you.

On 8/5/20 5:03 AM, Ying Xue wrote:

quoted

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 840bfdb..857d6f9 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -1983,6 +1983,45 @@ int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
 }
 EXPORT_SYMBOL(ipv6_chk_prefix);
 
+/**
+ * ipv6_dev_find - find the first device with a given source address.
+ * @net: the net namespace
+ * @addr: the source address
+ *
+ * The caller should be protected by RCU, or RTNL.
+ */
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
+{
+	unsigned int hash = inet6_addr_hash(net, addr);
+	struct inet6_ifaddr *ifp, *result = NULL;
+	struct net_device *dev = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
+		if (net_eq(dev_net(ifp->idev->dev), net) &&
+		    ipv6_addr_equal(&ifp->addr, addr)) {
+			result = ifp;
+			break;
+		}
+	}
+
+	if (!result) {
+		struct rt6_info *rt;
+
+		rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);

why is this needed? you have already walked the interfaces in the
namespace and not found the address. Doing a route lookup is beyond the
stated scope of this function.

quoted

+		if (rt) {
+			dev = rt->dst.dev;
+			ip6_rt_put(rt);
+		}
+	} else {
+		dev = result->idev->dev;
+	}
+	rcu_read_unlock();
+
+	return dev;
+}
+EXPORT_SYMBOL(ipv6_dev_find);
+
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
 				     struct net_device *dev, int strict)
 {

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

How do we handle link-local addresses?

--yoshfuji

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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;
+       }

Thanks.

--yoshfuji

quoted

 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
                                     const struct in6_addr *addr,
                                     struct net_device *dev, int strict);

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 840bfdb..857d6f9 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -1983,6 +1983,45 @@ int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
 }
 EXPORT_SYMBOL(ipv6_chk_prefix);

+/**
+ * ipv6_dev_find - find the first device with a given source address.
+ * @net: the net namespace
+ * @addr: the source address
+ *
+ * The caller should be protected by RCU, or RTNL.
+ */
+struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr)
+{
+       unsigned int hash = inet6_addr_hash(net, addr);
+       struct inet6_ifaddr *ifp, *result = NULL;
+       struct net_device *dev = NULL;
+
+       rcu_read_lock();
+       hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
+               if (net_eq(dev_net(ifp->idev->dev), net) &&
+                   ipv6_addr_equal(&ifp->addr, addr)) {
+                       result = ifp;
+                       break;
+               }
+       }
+
+       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;
+       }
+       rcu_read_unlock();
+
+       return dev;
+}
+EXPORT_SYMBOL(ipv6_dev_find);
+
 struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *addr,
                                     struct net_device *dev, int strict)
 {
--

2.1.0

On 8/6/20 2:55 AM, Xin Long wrote:

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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.

On Thu, Aug 6, 2020 at 10:03 PM David Ahern [off-list ref] wrote:

On 8/6/20 2:55 AM, Xin Long wrote:

quoted

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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.

Hi, David,
Sorry. it does. I misunderstood the code in __ip_dev_find().
I will delete the rt6_lookup() part from ipv6_dev_find().

Also for the compatibility, tipc part should change to:

@@ -741,10 +741,8 @@ static int tipc_udp_enable(struct net *net,

struct tipc_bearer *b,
                struct net_device *dev;

               dev = ipv6_dev_find(net, &local.ipv6);
               if (!dev)
                      ub->ifindex = dev->ifindex;

as when dev is not found from the hash list, it should fall back to
the old tipc code.

Ying, what do you think?

Hi,

2020年8月6日(木) 23:03 David Ahern [off-list ref]:

On 8/6/20 2:55 AM, Xin Long wrote:

quoted

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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.

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().

--yoshfuji

On Fri, Aug 7, 2020 at 5:26 PM Hideaki Yoshifuji
[off-list ref] wrote:

Hi,

2020年8月6日(木) 23:03 David Ahern [off-list ref]:

quoted

On 8/6/20 2:55 AM, Xin Long wrote:

quoted

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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 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?

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.

Thanks for your reviewing.

Hi,

2020年8月9日(日) 19:52 Xin Long [off-list ref]:

On Fri, Aug 7, 2020 at 5:26 PM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月6日(木) 23:03 David Ahern [off-list ref]:

quoted

On 8/6/20 2:55 AM, Xin Long wrote:

quoted

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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.

quoted

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.

On Tue, Aug 11, 2020 at 10:26 AM Hideaki Yoshifuji
[off-list ref] wrote:

Hi,

2020年8月9日(日) 19:52 Xin Long [off-list ref]:

quoted

On Fri, Aug 7, 2020 at 5:26 PM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月6日(木) 23:03 David Ahern [off-list ref]:

quoted

On 8/6/20 2:55 AM, Xin Long wrote:

quoted

On Thu, Aug 6, 2020 at 10:50 AM Hideaki Yoshifuji
[off-list ref] wrote:

quoted

Hi,

2020年8月4日(火) 0:35 Xin Long [off-list ref]:

quoted

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.xin@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.

right, thanks.

quoted

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.

okay.

quoted

quoted

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.

ipv6_chk_addr() is calling ipv6_chk_addr_and_flags(), which traverses
the addr hash list again. So I'm thinking to reuse the code of
ipv6_chk_addr_and_flags(), and do:

+static struct net_device *
+__ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
+                         const struct net_device *dev, bool skip_dev_check,
+                         int strict, u32 banned_flags)
 {
        unsigned int hash = inet6_addr_hash(net, addr);
        const struct net_device *l3mdev;

@@ -1926,12 +1918,29 @@ int ipv6_chk_addr_and_flags(struct net *net,

const struct in6_addr *addr,
                    (!dev || ifp->idev->dev == dev ||
                     !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))) {
                        rcu_read_unlock();
-                       return 1;
+                       return ifp->idev->dev;
                }
        }

        rcu_read_unlock();
-       return 0;
+       return NULL;
+}

and change these functions to :

int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
                            const struct net_device *dev, bool skip_dev_check,
                            int strict, u32 banned_flags)
{
        return __ipv6_chk_addr_and_flags(net, addr, dev, skip_dev_check,
                                         strict, banned_flags) ? 1 : 0;
}
EXPORT_SYMBOL(ipv6_chk_addr_and_flags);

struct net_device *ipv6_dev_find(struct net *net, const struct in6_addr *addr,
                                 struct net_device *dev)
{
        return __ipv6_chk_addr_and_flags(net, addr, NULL, 0, 1,
                                         IFA_F_TENTATIVE);
}
EXPORT_SYMBOL(ipv6_dev_find);

what do you think?