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[PATCH net-next v3 0/6] vxlan: cleanup and IPv6 link-local support

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  [PATCH net-next v3 0/6] vxlan: cleanup and IPv6 link-local support Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200
    [PATCH net-next v3 1/6] vxlan: refactor verification and application of configuration Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200
    [PATCH net-next v3 3/6] vxlan: improve validation of address family configuration Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200
    [PATCH net-next v3 4/6] vxlan: check valid combinations of address scopes Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200
    [PATCH net-next v3 5/6] vxlan: fix snooping for link-local IPv6 addresses Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200
    [PATCH net-next v3 6/6] vxlan: allow multiple VXLANs with same VNI for IPv6 link-local addresses Matthias Schiffer <mschiffer@universe-factory.net> - 2017-06-19 10:10 +0200

#1668880 — [PATCH net-next v3 0/6] vxlan: cleanup and IPv6 link-local support

Running VXLANs over IPv6 link-local addresses allows to use them as a
drop-in replacement for VLANs, avoiding to allocate additional outer IP
addresses to run the VXLAN over.

Since v1, I have added a lot more consistency checks to the address
configuration, making sure address families and scopes match. To simplify
the implementation, I also did some general refactoring of the
configuration handling in the new first patch of the series.

The second patch is more cleanup; is slightly touches OVS code, so that
list is in CC this time, too.

As in v1, the last two patches actually make VXLAN over IPv6 link-local
work, and allow multiple VXLANs with the same VNI and port, as long as
link-local addresses on different interfaces are used. As suggested, I now
store in the flags field if the VXLAN uses link-local addresses or not.

v3 removes log messages as suggested by Roopa Prabhu (as it is very unusual
for errors in netlink requests to be printed to the kernel log.) The commit
message of patch 5 has been extended to add a note about IPv4.

Matthias Schiffer (6):
  vxlan: refactor verification and application of configuration
  vxlan: get rid of redundant vxlan_dev.flags
  vxlan: improve validation of address family configuration
  vxlan: check valid combinations of address scopes
  vxlan: fix snooping for link-local IPv6 addresses
  vxlan: allow multiple VXLANs with same VNI for IPv6 link-local
    addresses

 drivers/net/vxlan.c           | 412 +++++++++++++++++++++++++-----------------
 include/net/vxlan.h           |   3 +-
 net/openvswitch/vport-vxlan.c |   4 +-
 3 files changed, 255 insertions(+), 164 deletions(-)

-- 
2.13.1

[toc] | [next] | [standalone]

#1668882 — [PATCH net-next v3 1/6] vxlan: refactor verification and application of configuration

The vxlan_dev_configure function was mixing validation and application of
the vxlan configuration; this could easily lead to bugs with the changelink
operation, as it was hard to see if the function wcould return an error
after parts of the configuration had already been applied.

This commit splits validation and application out of vxlan_dev_configure as
separate functions to make it clearer where error returns are allowed and
where the vxlan_dev or net_device may be configured. Log messages in these
functions are removed, as it is generally unexpected to find error output
for netlink requests in the kernel log. Userspace should be able to handle
errors based on the error codes returned via netlink just fine.

In addition, some validation and initialization is moved to vxlan_validate
and vxlan_setup respectively to improve grouping of similar settings.

Finally, this also fixes two actual bugs:

* if set, conf->mtu would overwrite dev->mtu in each changelink operation,
  reverting other changes of dev->mtu
* the "if (!conf->dst_port)" branch would never be run, as conf->dst_port
  was set in vxlan_setup before. This caused VXLAN-GPE to use the same
  default port as other VXLAN sockets instead of the intended IANA-assigned
  4790.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---

Notes:
    v2: new patch
    v3: remove kernel log messages

 drivers/net/vxlan.c | 208 ++++++++++++++++++++++++++++------------------------
 1 file changed, 111 insertions(+), 97 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 94ce98229828..9139f15a2ec1 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2623,6 +2623,10 @@ static void vxlan_setup(struct net_device *dev)
 	netif_keep_dst(dev);
 	dev->priv_flags |= IFF_NO_QUEUE;
 
+	/* MTU range: 68 - 65535 */
+	dev->min_mtu = ETH_MIN_MTU;
+	dev->max_mtu = ETH_MAX_MTU;
+
 	INIT_LIST_HEAD(&vxlan->next);
 	spin_lock_init(&vxlan->hash_lock);
 
@@ -2630,9 +2634,8 @@ static void vxlan_setup(struct net_device *dev)
 	vxlan->age_timer.function = vxlan_cleanup;
 	vxlan->age_timer.data = (unsigned long) vxlan;
 
-	vxlan->cfg.dst_port = htons(vxlan_port);
-
 	vxlan->dev = dev;
+	vxlan->net = dev_net(dev);
 
 	gro_cells_init(&vxlan->gro_cells, dev);
 
@@ -2701,11 +2704,19 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[])
 		}
 	}
 
+	if (tb[IFLA_MTU]) {
+		u32 mtu = nla_get_u32(data[IFLA_MTU]);
+
+		if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU)
+			return -EINVAL;
+	}
+
 	if (!data)
 		return -EINVAL;
 
 	if (data[IFLA_VXLAN_ID]) {
-		__u32 id = nla_get_u32(data[IFLA_VXLAN_ID]);
+		u32 id = nla_get_u32(data[IFLA_VXLAN_ID]);
+
 		if (id >= VXLAN_N_VID)
 			return -ERANGE;
 	}
@@ -2866,116 +2877,128 @@ static int vxlan_sock_add(struct vxlan_dev *vxlan)
 	return ret;
 }
 
-static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
-			       struct vxlan_config *conf,
-			       bool changelink)
+static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
+				 struct net_device **lower,
+				 struct vxlan_dev *old)
 {
 	struct vxlan_net *vn = net_generic(src_net, vxlan_net_id);
-	struct vxlan_dev *vxlan = netdev_priv(dev), *tmp;
-	struct vxlan_rdst *dst = &vxlan->default_dst;
-	unsigned short needed_headroom = ETH_HLEN;
+	struct vxlan_dev *tmp;
 	bool use_ipv6 = false;
-	__be16 default_port = vxlan->cfg.dst_port;
-	struct net_device *lowerdev = NULL;
 
-	if (!changelink) {
-		if (conf->flags & VXLAN_F_GPE) {
-			/* For now, allow GPE only together with
-			 * COLLECT_METADATA. This can be relaxed later; in such
-			 * case, the other side of the PtP link will have to be
-			 * provided.
-			 */
-			if ((conf->flags & ~VXLAN_F_ALLOWED_GPE) ||
-			    !(conf->flags & VXLAN_F_COLLECT_METADATA)) {
-				pr_info("unsupported combination of extensions\n");
-				return -EINVAL;
-			}
-			vxlan_raw_setup(dev);
-		} else {
-			vxlan_ether_setup(dev);
+	if (conf->flags & VXLAN_F_GPE) {
+		/* For now, allow GPE only together with
+		 * COLLECT_METADATA. This can be relaxed later; in such
+		 * case, the other side of the PtP link will have to be
+		 * provided.
+		 */
+		if ((conf->flags & ~VXLAN_F_ALLOWED_GPE) ||
+		    !(conf->flags & VXLAN_F_COLLECT_METADATA)) {
+			return -EINVAL;
 		}
-
-		/* MTU range: 68 - 65535 */
-		dev->min_mtu = ETH_MIN_MTU;
-		dev->max_mtu = ETH_MAX_MTU;
-		vxlan->net = src_net;
 	}
 
-	dst->remote_vni = conf->vni;
-
-	memcpy(&dst->remote_ip, &conf->remote_ip, sizeof(conf->remote_ip));
-
-	/* Unless IPv6 is explicitly requested, assume IPv4 */
-	if (!dst->remote_ip.sa.sa_family)
-		dst->remote_ip.sa.sa_family = AF_INET;
+	if (!conf->remote_ip.sa.sa_family)
+		conf->remote_ip.sa.sa_family = AF_INET;
 
-	if (dst->remote_ip.sa.sa_family == AF_INET6 ||
-	    vxlan->cfg.saddr.sa.sa_family == AF_INET6) {
+	if (conf->remote_ip.sa.sa_family == AF_INET6 ||
+	    conf->saddr.sa.sa_family == AF_INET6) {
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EPFNOSUPPORT;
 		use_ipv6 = true;
-		vxlan->flags |= VXLAN_F_IPV6;
+		conf->flags |= VXLAN_F_IPV6;
 	}
 
-	if (conf->label && !use_ipv6) {
-		pr_info("label only supported in use with IPv6\n");
+	if (conf->label && !use_ipv6)
 		return -EINVAL;
-	}
 
-	if (conf->remote_ifindex &&
-	    conf->remote_ifindex != vxlan->cfg.remote_ifindex) {
-		lowerdev = __dev_get_by_index(src_net, conf->remote_ifindex);
-		dst->remote_ifindex = conf->remote_ifindex;
+	if (conf->remote_ifindex) {
+		struct net_device *lowerdev;
 
-		if (!lowerdev) {
-			pr_info("ifindex %d does not exist\n",
-				dst->remote_ifindex);
+		lowerdev = __dev_get_by_index(src_net, conf->remote_ifindex);
+		if (!lowerdev)
 			return -ENODEV;
-		}
 
 #if IS_ENABLED(CONFIG_IPV6)
 		if (use_ipv6) {
 			struct inet6_dev *idev = __in6_dev_get(lowerdev);
-			if (idev && idev->cnf.disable_ipv6) {
-				pr_info("IPv6 is disabled via sysctl\n");
+			if (idev && idev->cnf.disable_ipv6)
 				return -EPERM;
-			}
 		}
 #endif
 
-		if (!conf->mtu)
-			dev->mtu = lowerdev->mtu -
-				   (use_ipv6 ? VXLAN6_HEADROOM : VXLAN_HEADROOM);
+		*lower = lowerdev;
+	} else {
+		if (vxlan_addr_multicast(&conf->remote_ip))
+			return -EINVAL;
 
-		needed_headroom = lowerdev->hard_header_len;
-	} else if (!conf->remote_ifindex &&
-		   vxlan_addr_multicast(&dst->remote_ip)) {
-		pr_info("multicast destination requires interface to be specified\n");
-		return -EINVAL;
+		*lower = NULL;
 	}
 
-	if (lowerdev) {
-		dev->gso_max_size = lowerdev->gso_max_size;
-		dev->gso_max_segs = lowerdev->gso_max_segs;
+	if (!conf->dst_port) {
+		if (conf->flags & VXLAN_F_GPE)
+			conf->dst_port = htons(4790); /* IANA VXLAN-GPE port */
+		else
+			conf->dst_port = htons(vxlan_port);
 	}
 
-	if (conf->mtu) {
-		int max_mtu = ETH_MAX_MTU;
+	if (!conf->age_interval)
+		conf->age_interval = FDB_AGE_DEFAULT;
 
-		if (lowerdev)
-			max_mtu = lowerdev->mtu;
+	list_for_each_entry(tmp, &vn->vxlan_list, next) {
+		if (tmp == old)
+			continue;
 
-		max_mtu -= (use_ipv6 ? VXLAN6_HEADROOM : VXLAN_HEADROOM);
+		if (tmp->cfg.vni == conf->vni &&
+		    (tmp->default_dst.remote_ip.sa.sa_family == AF_INET6 ||
+		     tmp->cfg.saddr.sa.sa_family == AF_INET6) == use_ipv6 &&
+		    tmp->cfg.dst_port == conf->dst_port &&
+		    (tmp->flags & VXLAN_F_RCV_FLAGS) ==
+		    (conf->flags & VXLAN_F_RCV_FLAGS))
+			return -EEXIST;
+	}
 
-		if (conf->mtu < dev->min_mtu || conf->mtu > dev->max_mtu)
-			return -EINVAL;
+	return 0;
+}
 
-		dev->mtu = conf->mtu;
+static void vxlan_config_apply(struct net_device *dev,
+			       struct vxlan_config *conf,
+			       struct net_device *lowerdev, bool changelink)
+{
+	struct vxlan_dev *vxlan = netdev_priv(dev);
+	struct vxlan_rdst *dst = &vxlan->default_dst;
+	unsigned short needed_headroom = ETH_HLEN;
+	bool use_ipv6 = !!(conf->flags & VXLAN_F_IPV6);
+	int max_mtu = ETH_MAX_MTU;
+
+	if (!changelink) {
+		if (conf->flags & VXLAN_F_GPE)
+			vxlan_raw_setup(dev);
+		else
+			vxlan_ether_setup(dev);
 
-		if (conf->mtu > max_mtu)
-			dev->mtu = max_mtu;
+		if (conf->mtu)
+			dev->mtu = conf->mtu;
 	}
 
+	dst->remote_vni = conf->vni;
+
+	memcpy(&dst->remote_ip, &conf->remote_ip, sizeof(conf->remote_ip));
+
+	if (lowerdev) {
+		dst->remote_ifindex = conf->remote_ifindex;
+
+		dev->gso_max_size = lowerdev->gso_max_size;
+		dev->gso_max_segs = lowerdev->gso_max_segs;
+
+		needed_headroom = lowerdev->hard_header_len;
+
+		max_mtu = lowerdev->mtu - (use_ipv6 ? VXLAN6_HEADROOM :
+					   VXLAN_HEADROOM);
+	}
+
+	if (dev->mtu > max_mtu)
+		dev->mtu = max_mtu;
+
 	if (use_ipv6 || conf->flags & VXLAN_F_COLLECT_METADATA)
 		needed_headroom += VXLAN6_HEADROOM;
 	else
@@ -2983,31 +3006,22 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
 	dev->needed_headroom = needed_headroom;
 
 	memcpy(&vxlan->cfg, conf, sizeof(*conf));
-	if (!vxlan->cfg.dst_port) {
-		if (conf->flags & VXLAN_F_GPE)
-			vxlan->cfg.dst_port = htons(4790); /* IANA VXLAN-GPE port */
-		else
-			vxlan->cfg.dst_port = default_port;
-	}
 	vxlan->flags |= conf->flags;
+}
 
-	if (!vxlan->cfg.age_interval)
-		vxlan->cfg.age_interval = FDB_AGE_DEFAULT;
+static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
+			       struct vxlan_config *conf,
+			       bool changelink)
+{
+	struct vxlan_dev *vxlan = netdev_priv(dev);
+	struct net_device *lowerdev;
+	int ret;
 
-	if (changelink)
-		return 0;
+	ret = vxlan_config_validate(src_net, conf, &lowerdev, vxlan);
+	if (ret)
+		return ret;
 
-	list_for_each_entry(tmp, &vn->vxlan_list, next) {
-		if (tmp->cfg.vni == conf->vni &&
-		    (tmp->default_dst.remote_ip.sa.sa_family == AF_INET6 ||
-		     tmp->cfg.saddr.sa.sa_family == AF_INET6) == use_ipv6 &&
-		    tmp->cfg.dst_port == vxlan->cfg.dst_port &&
-		    (tmp->flags & VXLAN_F_RCV_FLAGS) ==
-		    (vxlan->flags & VXLAN_F_RCV_FLAGS)) {
-			pr_info("duplicate VNI %u\n", be32_to_cpu(conf->vni));
-			return -EEXIST;
-		}
-	}
+	vxlan_config_apply(dev, conf, lowerdev, changelink);
 
 	return 0;
 }
-- 
2.13.1

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#1668884 — [PATCH net-next v3 3/6] vxlan: improve validation of address family configuration

Address families of source and destination addresses must match, and
changelink operations can't change the address family.

In addition, always use the VXLAN_F_IPV6 to check if a VXLAN device uses
IPv4 or IPv6.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---

Notes:
    v2: new patch
    v3: rebase

 drivers/net/vxlan.c | 39 ++++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index b4fce3b29647..00680cc597ac 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2484,10 +2484,7 @@ static int vxlan_change_mtu(struct net_device *dev, int new_mtu)
 	struct vxlan_rdst *dst = &vxlan->default_dst;
 	struct net_device *lowerdev = __dev_get_by_index(vxlan->net,
 							 dst->remote_ifindex);
-	bool use_ipv6 = false;
-
-	if (dst->remote_ip.sa.sa_family == AF_INET6)
-		use_ipv6 = true;
+	bool use_ipv6 = !!(vxlan->cfg.flags & VXLAN_F_IPV6);
 
 	/* This check is different than dev->max_mtu, because it looks at
 	 * the lowerdev->mtu, rather than the static dev->max_mtu
@@ -2897,11 +2894,20 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
 		}
 	}
 
-	if (!conf->remote_ip.sa.sa_family)
+	if (!conf->remote_ip.sa.sa_family && !conf->saddr.sa.sa_family) {
+		/* Unless IPv6 is explicitly requested, assume IPv4 */
 		conf->remote_ip.sa.sa_family = AF_INET;
+		conf->saddr.sa.sa_family = AF_INET;
+	} else if (!conf->remote_ip.sa.sa_family) {
+		conf->remote_ip.sa.sa_family = conf->saddr.sa.sa_family;
+	} else if (!conf->saddr.sa.sa_family) {
+		conf->saddr.sa.sa_family = conf->remote_ip.sa.sa_family;
+	}
+
+	if (conf->saddr.sa.sa_family != conf->remote_ip.sa.sa_family)
+		return -EINVAL;
 
-	if (conf->remote_ip.sa.sa_family == AF_INET6 ||
-	    conf->saddr.sa.sa_family == AF_INET6) {
+	if (conf->saddr.sa.sa_family == AF_INET6) {
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EPFNOSUPPORT;
 		use_ipv6 = true;
@@ -2949,11 +2955,9 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
 			continue;
 
 		if (tmp->cfg.vni == conf->vni &&
-		    (tmp->default_dst.remote_ip.sa.sa_family == AF_INET6 ||
-		     tmp->cfg.saddr.sa.sa_family == AF_INET6) == use_ipv6 &&
 		    tmp->cfg.dst_port == conf->dst_port &&
-		    (tmp->cfg.flags & VXLAN_F_RCV_FLAGS) ==
-		    (conf->flags & VXLAN_F_RCV_FLAGS))
+		    (tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) ==
+		    (conf->flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)))
 			return -EEXIST;
 	}
 
@@ -3084,22 +3088,35 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
 	}
 
 	if (data[IFLA_VXLAN_GROUP]) {
+		if (changelink && (conf->remote_ip.sa.sa_family != AF_INET))
+			return -EOPNOTSUPP;
+
 		conf->remote_ip.sin.sin_addr.s_addr = nla_get_in_addr(data[IFLA_VXLAN_GROUP]);
+		conf->remote_ip.sa.sa_family = AF_INET;
 	} else if (data[IFLA_VXLAN_GROUP6]) {
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EPFNOSUPPORT;
 
+		if (changelink && (conf->remote_ip.sa.sa_family != AF_INET6))
+			return -EOPNOTSUPP;
+
 		conf->remote_ip.sin6.sin6_addr = nla_get_in6_addr(data[IFLA_VXLAN_GROUP6]);
 		conf->remote_ip.sa.sa_family = AF_INET6;
 	}
 
 	if (data[IFLA_VXLAN_LOCAL]) {
+		if (changelink && (conf->saddr.sa.sa_family != AF_INET))
+			return -EOPNOTSUPP;
+
 		conf->saddr.sin.sin_addr.s_addr = nla_get_in_addr(data[IFLA_VXLAN_LOCAL]);
 		conf->saddr.sa.sa_family = AF_INET;
 	} else if (data[IFLA_VXLAN_LOCAL6]) {
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EPFNOSUPPORT;
 
+		if (changelink && (conf->saddr.sa.sa_family != AF_INET6))
+			return -EOPNOTSUPP;
+
 		/* TODO: respect scope id */
 		conf->saddr.sin6.sin6_addr = nla_get_in6_addr(data[IFLA_VXLAN_LOCAL6]);
 		conf->saddr.sa.sa_family = AF_INET6;
-- 
2.13.1

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#1668885 — [PATCH net-next v3 4/6] vxlan: check valid combinations of address scopes

* Multicast addresses are never valid as local address
* Link-local IPv6 unicast addresses may only be used as remote when the
  local address is link-local as well
* Don't allow link-local IPv6 local/remote addresses without interface

We also store in the flags field if link-local addresses are used for the
follow-up patches that actually make VXLAN over link-local IPv6 work.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---

Notes:
    v2: was "vxlan: don't allow link-local IPv6 local/remote addresses without
    interface" before. v2 does a lot more checks and adds the
    VXLAN_F_IPV6_LINKLOCAL flag.
    v3: remove kernel log messages

 drivers/net/vxlan.c | 29 +++++++++++++++++++++++++++++
 include/net/vxlan.h |  2 ++
 2 files changed, 31 insertions(+)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 00680cc597ac..d6d57317cbd5 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2907,11 +2907,35 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
 	if (conf->saddr.sa.sa_family != conf->remote_ip.sa.sa_family)
 		return -EINVAL;
 
+	if (vxlan_addr_multicast(&conf->saddr))
+		return -EINVAL;
+
 	if (conf->saddr.sa.sa_family == AF_INET6) {
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EPFNOSUPPORT;
 		use_ipv6 = true;
 		conf->flags |= VXLAN_F_IPV6;
+
+		if (!(conf->flags & VXLAN_F_COLLECT_METADATA)) {
+			int local_type =
+				ipv6_addr_type(&conf->saddr.sin6.sin6_addr);
+			int remote_type =
+				ipv6_addr_type(&conf->remote_ip.sin6.sin6_addr);
+
+			if (local_type & IPV6_ADDR_LINKLOCAL) {
+				if (!(remote_type & IPV6_ADDR_LINKLOCAL) &&
+				    (remote_type != IPV6_ADDR_ANY))
+					return -EINVAL;
+
+				conf->flags |= VXLAN_F_IPV6_LINKLOCAL;
+			} else {
+				if (remote_type ==
+				    (IPV6_ADDR_UNICAST | IPV6_ADDR_LINKLOCAL))
+					return -EINVAL;
+
+				conf->flags &= ~VXLAN_F_IPV6_LINKLOCAL;
+			}
+		}
 	}
 
 	if (conf->label && !use_ipv6)
@@ -2937,6 +2961,11 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
 		if (vxlan_addr_multicast(&conf->remote_ip))
 			return -EINVAL;
 
+#if IS_ENABLED(CONFIG_IPV6)
+		if (conf->flags & VXLAN_F_IPV6_LINKLOCAL)
+			return -EINVAL;
+#endif
+
 		*lower = NULL;
 	}
 
diff --git a/include/net/vxlan.h b/include/net/vxlan.h
index 479bb75789ea..b816a0a6686e 100644
--- a/include/net/vxlan.h
+++ b/include/net/vxlan.h
@@ -258,6 +258,7 @@ struct vxlan_dev {
 #define VXLAN_F_REMCSUM_NOPARTIAL	0x1000
 #define VXLAN_F_COLLECT_METADATA	0x2000
 #define VXLAN_F_GPE			0x4000
+#define VXLAN_F_IPV6_LINKLOCAL		0x8000
 
 /* Flags that are used in the receive path. These flags must match in
  * order for a socket to be shareable
@@ -272,6 +273,7 @@ struct vxlan_dev {
 /* Flags that can be set together with VXLAN_F_GPE. */
 #define VXLAN_F_ALLOWED_GPE		(VXLAN_F_GPE |			\
 					 VXLAN_F_IPV6 |			\
+					 VXLAN_F_IPV6_LINKLOCAL |	\
 					 VXLAN_F_UDP_ZERO_CSUM_TX |	\
 					 VXLAN_F_UDP_ZERO_CSUM6_TX |	\
 					 VXLAN_F_UDP_ZERO_CSUM6_RX |	\
-- 
2.13.1

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#1668886 — [PATCH net-next v3 5/6] vxlan: fix snooping for link-local IPv6 addresses

If VXLAN is run over link-local IPv6 addresses, it is necessary to store
the ifindex in the FDB entries. Otherwise, the used interface is undefined
and unicast communication will most likely fail.

Support for link-local IPv4 addresses should be possible as well, but as
the semantics aren't as well defined as for IPv6, and there doesn't seem to
be much interest in having the support, it's not implemented for now.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---

Notes:
    v2: use u32 instead of __u32
    v3: rebase, add note about IPv4 to commit message

 drivers/net/vxlan.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index d6d57317cbd5..45a8a5475f3d 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -957,16 +957,24 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
  */
 static bool vxlan_snoop(struct net_device *dev,
 			union vxlan_addr *src_ip, const u8 *src_mac,
-			__be32 vni)
+			u32 src_ifindex, __be32 vni)
 {
 	struct vxlan_dev *vxlan = netdev_priv(dev);
 	struct vxlan_fdb *f;
+	u32 ifindex = 0;
+
+#if IS_ENABLED(CONFIG_IPV6)
+	if (src_ip->sa.sa_family == AF_INET6 &&
+	    (ipv6_addr_type(&src_ip->sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL))
+		ifindex = src_ifindex;
+#endif
 
 	f = vxlan_find_mac(vxlan, src_mac, vni);
 	if (likely(f)) {
 		struct vxlan_rdst *rdst = first_remote_rcu(f);
 
-		if (likely(vxlan_addr_equal(&rdst->remote_ip, src_ip)))
+		if (likely(vxlan_addr_equal(&rdst->remote_ip, src_ip) &&
+			   rdst->remote_ifindex == ifindex))
 			return false;
 
 		/* Don't migrate static entries, drop packets */
@@ -993,7 +1001,7 @@ static bool vxlan_snoop(struct net_device *dev,
 					 vxlan->cfg.dst_port,
 					 vni,
 					 vxlan->default_dst.remote_vni,
-					 0, NTF_SELF);
+					 ifindex, NTF_SELF);
 		spin_unlock(&vxlan->hash_lock);
 	}
 
@@ -1264,6 +1272,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
 			  struct sk_buff *skb, __be32 vni)
 {
 	union vxlan_addr saddr;
+	u32 ifindex = skb->dev->ifindex;
 
 	skb_reset_mac_header(skb);
 	skb->protocol = eth_type_trans(skb, vxlan->dev);
@@ -1285,7 +1294,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
 	}
 
 	if ((vxlan->cfg.flags & VXLAN_F_LEARN) &&
-	    vxlan_snoop(skb->dev, &saddr, eth_hdr(skb)->h_source, vni))
+	    vxlan_snoop(skb->dev, &saddr, eth_hdr(skb)->h_source, ifindex, vni))
 		return false;
 
 	return true;
@@ -1994,7 +2003,8 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
 	}
 
 	if (dst_vxlan->cfg.flags & VXLAN_F_LEARN)
-		vxlan_snoop(skb->dev, &loopback, eth_hdr(skb)->h_source, vni);
+		vxlan_snoop(skb->dev, &loopback, eth_hdr(skb)->h_source, 0,
+			    vni);
 
 	u64_stats_update_begin(&tx_stats->syncp);
 	tx_stats->tx_packets++;
-- 
2.13.1

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#1668887 — [PATCH net-next v3 6/6] vxlan: allow multiple VXLANs with same VNI for IPv6 link-local addresses

As link-local addresses are only valid for a single interface, we can allow
to use the same VNI for multiple independent VXLANs, as long as the used
interfaces are distinct. This way, VXLANs can always be used as a drop-in
replacement for VLANs with greater ID space.

This also extends VNI lookup to respect the ifindex when link-local IPv6
addresses are used, so using the same VNI on multiple interfaces can
actually work.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---

Notes:
    v2: use VXLAN_F_IPV6_LINKLOCAL in vxlan_vs_find_vni; rebase
    v3: rebase

 drivers/net/vxlan.c | 68 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 45 insertions(+), 23 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 45a8a5475f3d..653b2bb32be1 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -226,7 +226,8 @@ static struct vxlan_sock *vxlan_find_sock(struct net *net, sa_family_t family,
 	return NULL;
 }
 
-static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, __be32 vni)
+static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, int ifindex,
+					   __be32 vni)
 {
 	struct vxlan_dev *vxlan;
 
@@ -235,17 +236,27 @@ static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, __be32 vni)
 		vni = 0;
 
 	hlist_for_each_entry_rcu(vxlan, vni_head(vs, vni), hlist) {
-		if (vxlan->default_dst.remote_vni == vni)
-			return vxlan;
+		if (vxlan->default_dst.remote_vni != vni)
+			continue;
+
+		if (IS_ENABLED(CONFIG_IPV6)) {
+			const struct vxlan_config *cfg = &vxlan->cfg;
+
+			if ((cfg->flags & VXLAN_F_IPV6_LINKLOCAL) &&
+			    cfg->remote_ifindex != ifindex)
+				continue;
+		}
+
+		return vxlan;
 	}
 
 	return NULL;
 }
 
 /* Look up VNI in a per net namespace table */
-static struct vxlan_dev *vxlan_find_vni(struct net *net, __be32 vni,
-					sa_family_t family, __be16 port,
-					u32 flags)
+static struct vxlan_dev *vxlan_find_vni(struct net *net, int ifindex,
+					__be32 vni, sa_family_t family,
+					__be16 port, u32 flags)
 {
 	struct vxlan_sock *vs;
 
@@ -253,7 +264,7 @@ static struct vxlan_dev *vxlan_find_vni(struct net *net, __be32 vni,
 	if (!vs)
 		return NULL;
 
-	return vxlan_vs_find_vni(vs, vni);
+	return vxlan_vs_find_vni(vs, ifindex, vni);
 }
 
 /* Fill in neighbour message in skbuff. */
@@ -1360,7 +1371,7 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 
 	vni = vxlan_vni(vxlan_hdr(skb)->vx_vni);
 
-	vxlan = vxlan_vs_find_vni(vs, vni);
+	vxlan = vxlan_vs_find_vni(vs, skb->dev->ifindex, vni);
 	if (!vxlan)
 		goto drop;
 
@@ -2022,8 +2033,10 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
 }
 
 static int encap_bypass_if_local(struct sk_buff *skb, struct net_device *dev,
-				 struct vxlan_dev *vxlan, union vxlan_addr *daddr,
-				 __be16 dst_port, __be32 vni, struct dst_entry *dst,
+				 struct vxlan_dev *vxlan,
+				 union vxlan_addr *daddr,
+				 __be16 dst_port, int dst_ifindex, __be32 vni,
+				 struct dst_entry *dst,
 				 u32 rt_flags)
 {
 #if IS_ENABLED(CONFIG_IPV6)
@@ -2039,7 +2052,7 @@ static int encap_bypass_if_local(struct sk_buff *skb, struct net_device *dev,
 		struct vxlan_dev *dst_vxlan;
 
 		dst_release(dst);
-		dst_vxlan = vxlan_find_vni(vxlan->net, vni,
+		dst_vxlan = vxlan_find_vni(vxlan->net, dst_ifindex, vni,
 					   daddr->sa.sa_family, dst_port,
 					   vxlan->cfg.flags);
 		if (!dst_vxlan) {
@@ -2071,6 +2084,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 	struct dst_entry *ndst = NULL;
 	__be32 vni, label;
 	__u8 tos, ttl;
+	int ifindex;
 	int err;
 	u32 flags = vxlan->cfg.flags;
 	bool udp_sum = false;
@@ -2091,6 +2105,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 
 		dst_port = rdst->remote_port ? rdst->remote_port : vxlan->cfg.dst_port;
 		vni = (rdst->remote_vni) ? : default_vni;
+		ifindex = rdst->remote_ifindex;
 		local_ip = vxlan->cfg.saddr;
 		dst_cache = &rdst->dst_cache;
 		md->gbp = skb->mark;
@@ -2124,6 +2139,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		dst = &remote_ip;
 		dst_port = info->key.tp_dst ? : vxlan->cfg.dst_port;
 		vni = tunnel_id_to_key32(info->key.tun_id);
+		ifindex = 0;
 		dst_cache = &info->dst_cache;
 		if (info->options_len)
 			md = ip_tunnel_info_opts(info);
@@ -2141,8 +2157,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		struct rtable *rt;
 		__be16 df = 0;
 
-		rt = vxlan_get_route(vxlan, dev, sock4, skb,
-				     rdst ? rdst->remote_ifindex : 0, tos,
+		rt = vxlan_get_route(vxlan, dev, sock4, skb, ifindex, tos,
 				     dst->sin.sin_addr.s_addr,
 				     &local_ip.sin.sin_addr.s_addr,
 				     dst_port, src_port,
@@ -2155,8 +2170,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		/* Bypass encapsulation if the destination is local */
 		if (!info) {
 			err = encap_bypass_if_local(skb, dev, vxlan, dst,
-						    dst_port, vni, &rt->dst,
-						    rt->rt_flags);
+						    dst_port, ifindex, vni,
+						    &rt->dst, rt->rt_flags);
 			if (err)
 				goto out_unlock;
 		} else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT) {
@@ -2178,8 +2193,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 	} else {
 		struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock);
 
-		ndst = vxlan6_get_route(vxlan, dev, sock6, skb,
-					rdst ? rdst->remote_ifindex : 0, tos,
+		ndst = vxlan6_get_route(vxlan, dev, sock6, skb, ifindex, tos,
 					label, &dst->sin6.sin6_addr,
 					&local_ip.sin6.sin6_addr,
 					dst_port, src_port,
@@ -2194,8 +2208,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 			u32 rt6i_flags = ((struct rt6_info *)ndst)->rt6i_flags;
 
 			err = encap_bypass_if_local(skb, dev, vxlan, dst,
-						    dst_port, vni, ndst,
-						    rt6i_flags);
+						    dst_port, ifindex, vni,
+						    ndst, rt6i_flags);
 			if (err)
 				goto out_unlock;
 		}
@@ -2993,11 +3007,19 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
 		if (tmp == old)
 			continue;
 
-		if (tmp->cfg.vni == conf->vni &&
-		    tmp->cfg.dst_port == conf->dst_port &&
-		    (tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) ==
+		if (tmp->cfg.vni != conf->vni)
+			continue;
+		if (tmp->cfg.dst_port != conf->dst_port)
+			continue;
+		if ((tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) !=
 		    (conf->flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)))
-			return -EEXIST;
+			continue;
+
+		if ((conf->flags & VXLAN_F_IPV6_LINKLOCAL) &&
+		    tmp->cfg.remote_ifindex != conf->remote_ifindex)
+			continue;
+
+		return -EEXIST;
 	}
 
 	return 0;
-- 
2.13.1

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