From: Roopa Prabhu <ro...@cumulusnetworks.com>

This patch adds changelink rtnl op support for vxlan netdevs.
code changes involve:
    - refactor vxlan_newlink into vxlan_nl2conf to be
    used by vxlan_newlink and vxlan_changelink
    - vxlan_nl2conf and vxlan_dev_configure take a
    changelink argument to isolate changelink checks
    and updates.
    - Allow changing only a few attributes:
        - return -EOPNOTSUPP for attributes that cannot
        be changed for now. Incremental patches can
        make the non-supported one available in the future
        if needed.

Signed-off-by: Roopa Prabhu <ro...@cumulusnetworks.com>
---
 drivers/net/vxlan.c |  383 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 270 insertions(+), 113 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index c5db8f8..87f63f6 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2835,39 +2835,40 @@ static int vxlan_sock_add(struct vxlan_dev *vxlan)
 }
 
 static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
-                              struct vxlan_config *conf)
+                              struct vxlan_config *conf,
+                              bool changelink)
 {
        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;
-       int err;
        bool use_ipv6 = false;
        __be16 default_port = vxlan->cfg.dst_port;
        struct net_device *lowerdev = NULL;
 
-       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;
+       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);
                }
 
-               vxlan_raw_setup(dev);
-       } else {
-               vxlan_ether_setup(dev);
+               /* MTU range: 68 - 65535 */
+               dev->min_mtu = ETH_MIN_MTU;
+               dev->max_mtu = ETH_MAX_MTU;
+               vxlan->net = src_net;
        }
 
-       /* 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));
@@ -2889,12 +2890,14 @@ static int vxlan_dev_configure(struct net *src_net, 
struct net_device *dev,
                return -EINVAL;
        }
 
-       if (conf->remote_ifindex) {
+       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 (!lowerdev) {
-                       pr_info("ifindex %d does not exist\n", 
dst->remote_ifindex);
+                       pr_info("ifindex %d does not exist\n",
+                               dst->remote_ifindex);
                        return -ENODEV;
                }
 
@@ -2913,7 +2916,8 @@ static int vxlan_dev_configure(struct net *src_net, 
struct net_device *dev,
                                   (use_ipv6 ? VXLAN6_HEADROOM : 
VXLAN_HEADROOM);
 
                needed_headroom = lowerdev->hard_header_len;
-       } else if (vxlan_addr_multicast(&dst->remote_ip)) {
+       } else if (!conf->remote_ifindex &&
+                  vxlan_addr_multicast(&dst->remote_ip)) {
                pr_info("multicast destination requires interface to be 
specified\n");
                return -EINVAL;
        }
@@ -2953,6 +2957,9 @@ static int vxlan_dev_configure(struct net *src_net, 
struct net_device *dev,
        if (!vxlan->cfg.age_interval)
                vxlan->cfg.age_interval = FDB_AGE_DEFAULT;
 
+       if (changelink)
+               return 0;
+
        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 ||
@@ -2965,147 +2972,296 @@ static int vxlan_dev_configure(struct net *src_net, 
struct net_device *dev,
                }
        }
 
-       dev->ethtool_ops = &vxlan_ethtool_ops;
-
-       /* create an fdb entry for a valid default destination */
-       if (!vxlan_addr_any(&vxlan->default_dst.remote_ip)) {
-               err = vxlan_fdb_create(vxlan, all_zeros_mac,
-                                      &vxlan->default_dst.remote_ip,
-                                      NUD_REACHABLE|NUD_PERMANENT,
-                                      NLM_F_EXCL|NLM_F_CREATE,
-                                      vxlan->cfg.dst_port,
-                                      vxlan->default_dst.remote_vni,
-                                      vxlan->default_dst.remote_vni,
-                                      vxlan->default_dst.remote_ifindex,
-                                      NTF_SELF);
-               if (err)
-                       return err;
-       }
-
-       err = register_netdevice(dev);
-       if (err) {
-               vxlan_fdb_delete_default(vxlan, vxlan->cfg.vni);
-               return err;
-       }
-
-       list_add(&vxlan->next, &vn->vxlan_list);
-
        return 0;
 }
 
-static int vxlan_newlink(struct net *src_net, struct net_device *dev,
-                        struct nlattr *tb[], struct nlattr *data[])
+static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
+                        struct net_device *dev, struct vxlan_config *conf,
+                        bool changelink)
 {
-       struct vxlan_config conf;
+       struct vxlan_dev *vxlan = netdev_priv(dev);
 
-       memset(&conf, 0, sizeof(conf));
+       memset(conf, 0, sizeof(*conf));
 
-       if (data[IFLA_VXLAN_ID])
-               conf.vni = cpu_to_be32(nla_get_u32(data[IFLA_VXLAN_ID]));
+       /* if changelink operation, start with old existing cfg */
+       if (changelink)
+               memcpy(conf, &vxlan->cfg, sizeof(*conf));
+
+       if (data[IFLA_VXLAN_ID]) {
+               __be32 vni = cpu_to_be32(nla_get_u32(data[IFLA_VXLAN_ID]));
+
+               if (changelink && (vni != conf->vni))
+                       return -EOPNOTSUPP;
+               conf->vni = cpu_to_be32(nla_get_u32(data[IFLA_VXLAN_ID]));
+       }
 
        if (data[IFLA_VXLAN_GROUP]) {
-               conf.remote_ip.sin.sin_addr.s_addr = 
nla_get_in_addr(data[IFLA_VXLAN_GROUP]);
+               conf->remote_ip.sin.sin_addr.s_addr = 
nla_get_in_addr(data[IFLA_VXLAN_GROUP]);
        } else if (data[IFLA_VXLAN_GROUP6]) {
                if (!IS_ENABLED(CONFIG_IPV6))
                        return -EPFNOSUPPORT;
 
-               conf.remote_ip.sin6.sin6_addr = 
nla_get_in6_addr(data[IFLA_VXLAN_GROUP6]);
-               conf.remote_ip.sa.sa_family = AF_INET6;
+               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]) {
-               conf.saddr.sin.sin_addr.s_addr = 
nla_get_in_addr(data[IFLA_VXLAN_LOCAL]);
-               conf.saddr.sa.sa_family = AF_INET;
+               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;
 
                /* TODO: respect scope id */
-               conf.saddr.sin6.sin6_addr = 
nla_get_in6_addr(data[IFLA_VXLAN_LOCAL6]);
-               conf.saddr.sa.sa_family = AF_INET6;
+               conf->saddr.sin6.sin6_addr = 
nla_get_in6_addr(data[IFLA_VXLAN_LOCAL6]);
+               conf->saddr.sa.sa_family = AF_INET6;
        }
 
        if (data[IFLA_VXLAN_LINK])
-               conf.remote_ifindex = nla_get_u32(data[IFLA_VXLAN_LINK]);
+               conf->remote_ifindex = nla_get_u32(data[IFLA_VXLAN_LINK]);
 
        if (data[IFLA_VXLAN_TOS])
-               conf.tos  = nla_get_u8(data[IFLA_VXLAN_TOS]);
+               conf->tos  = nla_get_u8(data[IFLA_VXLAN_TOS]);
 
        if (data[IFLA_VXLAN_TTL])
-               conf.ttl = nla_get_u8(data[IFLA_VXLAN_TTL]);
+               conf->ttl = nla_get_u8(data[IFLA_VXLAN_TTL]);
 
        if (data[IFLA_VXLAN_LABEL])
-               conf.label = nla_get_be32(data[IFLA_VXLAN_LABEL]) &
+               conf->label = nla_get_be32(data[IFLA_VXLAN_LABEL]) &
                             IPV6_FLOWLABEL_MASK;
 
-       if (!data[IFLA_VXLAN_LEARNING] || nla_get_u8(data[IFLA_VXLAN_LEARNING]))
-               conf.flags |= VXLAN_F_LEARN;
+       if (data[IFLA_VXLAN_LEARNING]) {
+               if (nla_get_u8(data[IFLA_VXLAN_LEARNING])) {
+                       conf->flags |= VXLAN_F_LEARN;
+               } else {
+                       conf->flags &= ~VXLAN_F_LEARN;
+                       vxlan->flags &= ~VXLAN_F_LEARN;
+               }
+       } else if (!changelink) {
+               /* default to learn on a new device */
+               conf->flags |= VXLAN_F_LEARN;
+       }
 
-       if (data[IFLA_VXLAN_AGEING])
-               conf.age_interval = nla_get_u32(data[IFLA_VXLAN_AGEING]);
+       if (data[IFLA_VXLAN_AGEING]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->age_interval = nla_get_u32(data[IFLA_VXLAN_AGEING]);
+       }
 
-       if (data[IFLA_VXLAN_PROXY] && nla_get_u8(data[IFLA_VXLAN_PROXY]))
-               conf.flags |= VXLAN_F_PROXY;
+       if (data[IFLA_VXLAN_PROXY]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_PROXY]))
+                       conf->flags |= VXLAN_F_PROXY;
+       }
 
-       if (data[IFLA_VXLAN_RSC] && nla_get_u8(data[IFLA_VXLAN_RSC]))
-               conf.flags |= VXLAN_F_RSC;
+       if (data[IFLA_VXLAN_RSC]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_RSC]))
+                       conf->flags |= VXLAN_F_RSC;
+       }
 
-       if (data[IFLA_VXLAN_L2MISS] && nla_get_u8(data[IFLA_VXLAN_L2MISS]))
-               conf.flags |= VXLAN_F_L2MISS;
+       if (data[IFLA_VXLAN_L2MISS]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_L2MISS]))
+                       conf->flags |= VXLAN_F_L2MISS;
+       }
 
-       if (data[IFLA_VXLAN_L3MISS] && nla_get_u8(data[IFLA_VXLAN_L3MISS]))
-               conf.flags |= VXLAN_F_L3MISS;
+       if (data[IFLA_VXLAN_L3MISS]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_L3MISS]))
+                       conf->flags |= VXLAN_F_L3MISS;
+       }
 
-       if (data[IFLA_VXLAN_LIMIT])
-               conf.addrmax = nla_get_u32(data[IFLA_VXLAN_LIMIT]);
+       if (data[IFLA_VXLAN_LIMIT]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->addrmax = nla_get_u32(data[IFLA_VXLAN_LIMIT]);
+       }
 
-       if (data[IFLA_VXLAN_COLLECT_METADATA] &&
-           nla_get_u8(data[IFLA_VXLAN_COLLECT_METADATA]))
-               conf.flags |= VXLAN_F_COLLECT_METADATA;
+       if (data[IFLA_VXLAN_COLLECT_METADATA]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_COLLECT_METADATA]))
+                       conf->flags |= VXLAN_F_COLLECT_METADATA;
+       }
 
        if (data[IFLA_VXLAN_PORT_RANGE]) {
-               const struct ifla_vxlan_port_range *p
-                       = nla_data(data[IFLA_VXLAN_PORT_RANGE]);
-               conf.port_min = ntohs(p->low);
-               conf.port_max = ntohs(p->high);
+               if (!changelink) {
+                       const struct ifla_vxlan_port_range *p
+                               = nla_data(data[IFLA_VXLAN_PORT_RANGE]);
+                       conf->port_min = ntohs(p->low);
+                       conf->port_max = ntohs(p->high);
+               } else {
+                       return -EOPNOTSUPP;
+               }
        }
 
-       if (data[IFLA_VXLAN_PORT])
-               conf.dst_port = nla_get_be16(data[IFLA_VXLAN_PORT]);
+       if (data[IFLA_VXLAN_PORT]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->dst_port = nla_get_be16(data[IFLA_VXLAN_PORT]);
+       }
 
-       if (data[IFLA_VXLAN_UDP_CSUM] &&
-           !nla_get_u8(data[IFLA_VXLAN_UDP_CSUM]))
-               conf.flags |= VXLAN_F_UDP_ZERO_CSUM_TX;
+       if (data[IFLA_VXLAN_UDP_CSUM]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (!nla_get_u8(data[IFLA_VXLAN_UDP_CSUM]))
+                       conf->flags |= VXLAN_F_UDP_ZERO_CSUM_TX;
+       }
 
-       if (data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX] &&
-           nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]))
-               conf.flags |= VXLAN_F_UDP_ZERO_CSUM6_TX;
+       if (data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_TX]))
+                       conf->flags |= VXLAN_F_UDP_ZERO_CSUM6_TX;
+       }
 
-       if (data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX] &&
-           nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX]))
-               conf.flags |= VXLAN_F_UDP_ZERO_CSUM6_RX;
+       if (data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_UDP_ZERO_CSUM6_RX]))
+                       conf->flags |= VXLAN_F_UDP_ZERO_CSUM6_RX;
+       }
 
-       if (data[IFLA_VXLAN_REMCSUM_TX] &&
-           nla_get_u8(data[IFLA_VXLAN_REMCSUM_TX]))
-               conf.flags |= VXLAN_F_REMCSUM_TX;
+       if (data[IFLA_VXLAN_REMCSUM_TX]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_REMCSUM_TX]))
+                       conf->flags |= VXLAN_F_REMCSUM_TX;
+       }
 
-       if (data[IFLA_VXLAN_REMCSUM_RX] &&
-           nla_get_u8(data[IFLA_VXLAN_REMCSUM_RX]))
-               conf.flags |= VXLAN_F_REMCSUM_RX;
+       if (data[IFLA_VXLAN_REMCSUM_RX]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               if (nla_get_u8(data[IFLA_VXLAN_REMCSUM_RX]))
+                       conf->flags |= VXLAN_F_REMCSUM_RX;
+       }
+
+       if (data[IFLA_VXLAN_GBP]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->flags |= VXLAN_F_GBP;
+       }
+
+       if (data[IFLA_VXLAN_GPE]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->flags |= VXLAN_F_GPE;
+       }
+
+       if (data[IFLA_VXLAN_REMCSUM_NOPARTIAL]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->flags |= VXLAN_F_REMCSUM_NOPARTIAL;
+       }
+
+       if (tb[IFLA_MTU]) {
+               if (changelink)
+                       return -EOPNOTSUPP;
+               conf->mtu = nla_get_u32(tb[IFLA_MTU]);
+       }
+
+       return 0;
+}
+
+static int vxlan_newlink(struct net *src_net, struct net_device *dev,
+                        struct nlattr *tb[], struct nlattr *data[])
+{
+       struct vxlan_net *vn = net_generic(src_net, vxlan_net_id);
+       struct vxlan_dev *vxlan = netdev_priv(dev);
+       struct vxlan_config conf;
+       int err;
+
+       err = vxlan_nl2conf(tb, data, dev, &conf, false);
+       if (err)
+               return err;
+
+       err = vxlan_dev_configure(src_net, dev, &conf, false);
+       if (err)
+               return err;
+
+       dev->ethtool_ops = &vxlan_ethtool_ops;
+
+       /* create an fdb entry for a valid default destination */
+       if (!vxlan_addr_any(&vxlan->default_dst.remote_ip)) {
+               err = vxlan_fdb_create(vxlan, all_zeros_mac,
+                                      &vxlan->default_dst.remote_ip,
+                                      NUD_REACHABLE | NUD_PERMANENT,
+                                      NLM_F_EXCL | NLM_F_CREATE,
+                                      vxlan->cfg.dst_port,
+                                      vxlan->default_dst.remote_vni,
+                                      vxlan->default_dst.remote_vni,
+                                      vxlan->default_dst.remote_ifindex,
+                                      NTF_SELF);
+               if (err)
+                       return err;
+       }
+
+       err = register_netdevice(dev);
+       if (err) {
+               vxlan_fdb_delete_default(vxlan, vxlan->default_dst.remote_vni);
+               return err;
+       }
+
+       list_add(&vxlan->next, &vn->vxlan_list);
+
+       return 0;
+}
 
-       if (data[IFLA_VXLAN_GBP])
-               conf.flags |= VXLAN_F_GBP;
+static int vxlan_changelink(struct net_device *dev, struct nlattr *tb[],
+                           struct nlattr *data[])
+{
+       struct vxlan_dev *vxlan = netdev_priv(dev);
+       struct vxlan_rdst *dst = &vxlan->default_dst;
+       struct vxlan_rdst old_dst;
+       struct vxlan_config conf;
+       int err;
+
+       err = vxlan_nl2conf(tb, data,
+                           dev, &conf, true);
+       if (err)
+               return err;
 
-       if (data[IFLA_VXLAN_GPE])
-               conf.flags |= VXLAN_F_GPE;
+       memcpy(&old_dst, dst, sizeof(struct vxlan_rdst));
 
-       if (data[IFLA_VXLAN_REMCSUM_NOPARTIAL])
-               conf.flags |= VXLAN_F_REMCSUM_NOPARTIAL;
+       err = vxlan_dev_configure(vxlan->net, dev, &conf, true);
+       if (err)
+               return err;
 
-       if (tb[IFLA_MTU])
-               conf.mtu = nla_get_u32(tb[IFLA_MTU]);
+       /* handle default dst entry */
+       if (!vxlan_addr_equal(&dst->remote_ip, &old_dst.remote_ip)) {
+               spin_lock_bh(&vxlan->hash_lock);
+               if (!vxlan_addr_any(&old_dst.remote_ip))
+                       __vxlan_fdb_delete(vxlan, all_zeros_mac,
+                                          old_dst.remote_ip,
+                                          vxlan->cfg.dst_port,
+                                          old_dst.remote_vni,
+                                          old_dst.remote_vni,
+                                          old_dst.remote_ifindex, 0);
+
+               if (!vxlan_addr_any(&dst->remote_ip)) {
+                       err = vxlan_fdb_create(vxlan, all_zeros_mac,
+                                              &dst->remote_ip,
+                                              NUD_REACHABLE | NUD_PERMANENT,
+                                              NLM_F_CREATE | NLM_F_APPEND,
+                                              vxlan->cfg.dst_port,
+                                              dst->remote_vni,
+                                              dst->remote_vni,
+                                              dst->remote_ifindex,
+                                              NTF_SELF);
+                       if (err) {
+                               spin_unlock_bh(&vxlan->hash_lock);
+                               return err;
+                       }
+               }
+               spin_unlock_bh(&vxlan->hash_lock);
+       }
 
-       return vxlan_dev_configure(src_net, dev, &conf);
+       return 0;
 }
 
 static void vxlan_dellink(struct net_device *dev, struct list_head *head)
@@ -3261,6 +3417,7 @@ static struct net *vxlan_get_link_net(const struct 
net_device *dev)
        .setup          = vxlan_setup,
        .validate       = vxlan_validate,
        .newlink        = vxlan_newlink,
+       .changelink     = vxlan_changelink,
        .dellink        = vxlan_dellink,
        .get_size       = vxlan_get_size,
        .fill_info      = vxlan_fill_info,
@@ -3282,7 +3439,7 @@ struct net_device *vxlan_dev_create(struct net *net, 
const char *name,
        if (IS_ERR(dev))
                return dev;
 
-       err = vxlan_dev_configure(net, dev, conf);
+       err = vxlan_dev_configure(net, dev, conf, false);
        if (err < 0) {
                free_netdev(dev);
                return ERR_PTR(err);
-- 
1.7.10.4

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