rtnetlink: Link address family API

Each net_device contains address family specific data such as
per device settings and statistics. We already expose this data
via procfs/sysfs and partially netlink.

The netlink method requires the requester to send one RTM_GETLINK
request for each address family it wishes to receive data of
and then merge this data itself.

This patch implements a new API which combines all address family
specific link data in a new netlink attribute IFLA_AF_SPEC.
IFLA_AF_SPEC contains a sequence of nested attributes, one for each
address family which in turn defines the structure of its own
attribute. Example:

   [IFLA_AF_SPEC] = {
       [AF_INET] = {
           [IFLA_INET_CONF] = ...,
       },
       [AF_INET6] = {
           [IFLA_INET6_FLAGS] = ...,
           [IFLA_INET6_CONF] = ...,
       }
   }

The API also allows for address families to implement a function
which parses the IFLA_AF_SPEC attribute sent by userspace to
implement address family specific link options.

Signed-off-by: Thomas Graf <tgraf@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 2fc66dd..443d04a 100644 (file)
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -80,6 +80,24 @@ struct rtnl_link_ifmap {
        __u8    port;
 };
 
+/*
+ * IFLA_AF_SPEC
+ *   Contains nested attributes for address family specific attributes.
+ *   Each address family may create a attribute with the address family
+ *   number as type and create its own attribute structure in it.
+ *
+ *   Example:
+ *   [IFLA_AF_SPEC] = {
+ *       [AF_INET] = {
+ *           [IFLA_INET_CONF] = ...,
+ *       },
+ *       [AF_INET6] = {
+ *           [IFLA_INET6_FLAGS] = ...,
+ *           [IFLA_INET6_CONF] = ...,
+ *       }
+ *   }
+ */
+
 enum {
        IFLA_UNSPEC,
        IFLA_ADDRESS,
@@ -116,6 +134,7 @@ enum {
        IFLA_STATS64,
        IFLA_VF_PORTS,
        IFLA_PORT_SELF,
+       IFLA_AF_SPEC,
        __IFLA_MAX
 };
 

diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index e013c68..35be0bb 100644 (file)
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -83,6 +83,37 @@ extern void  __rtnl_link_unregister(struct rtnl_link_ops *ops);
 extern int     rtnl_link_register(struct rtnl_link_ops *ops);
 extern void    rtnl_link_unregister(struct rtnl_link_ops *ops);
 
+/**
+ *     struct rtnl_af_ops - rtnetlink address family operations
+ *
+ *     @list: Used internally
+ *     @family: Address family
+ *     @fill_link_af: Function to fill IFLA_AF_SPEC with address family
+ *                    specific netlink attributes.
+ *     @get_link_af_size: Function to calculate size of address family specific
+ *                        netlink attributes exlusive the container attribute.
+ *     @parse_link_af: Function to parse a IFLA_AF_SPEC attribute and modify
+ *                     net_device accordingly.
+ */
+struct rtnl_af_ops {
+       struct list_head        list;
+       int                     family;
+
+       int                     (*fill_link_af)(struct sk_buff *skb,
+                                               const struct net_device *dev);
+       size_t                  (*get_link_af_size)(const struct net_device *dev);
+
+       int                     (*parse_link_af)(struct net_device *dev,
+                                                const struct nlattr *attr);
+};
+
+extern int     __rtnl_af_register(struct rtnl_af_ops *ops);
+extern void    __rtnl_af_unregister(struct rtnl_af_ops *ops);
+
+extern int     rtnl_af_register(struct rtnl_af_ops *ops);
+extern void    rtnl_af_unregister(struct rtnl_af_ops *ops);
+
+
 extern struct net *rtnl_link_get_net(struct net *src_net, struct nlattr *tb[]);
 extern struct net_device *rtnl_create_link(struct net *src_net, struct net *net,
        char *ifname, const struct rtnl_link_ops *ops, struct nlattr *tb[]);

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 841c287..bf69e58 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -362,6 +362,95 @@ static size_t rtnl_link_get_size(const struct net_device *dev)
        return size;
 }
 
+static LIST_HEAD(rtnl_af_ops);
+
+static const struct rtnl_af_ops *rtnl_af_lookup(const int family)
+{
+       const struct rtnl_af_ops *ops;
+
+       list_for_each_entry(ops, &rtnl_af_ops, list) {
+               if (ops->family == family)
+                       return ops;
+       }
+
+       return NULL;
+}
+
+/**
+ * __rtnl_af_register - Register rtnl_af_ops with rtnetlink.
+ * @ops: struct rtnl_af_ops * to register
+ *
+ * The caller must hold the rtnl_mutex.
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int __rtnl_af_register(struct rtnl_af_ops *ops)
+{
+       list_add_tail(&ops->list, &rtnl_af_ops);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(__rtnl_af_register);
+
+/**
+ * rtnl_af_register - Register rtnl_af_ops with rtnetlink.
+ * @ops: struct rtnl_af_ops * to register
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int rtnl_af_register(struct rtnl_af_ops *ops)
+{
+       int err;
+
+       rtnl_lock();
+       err = __rtnl_af_register(ops);
+       rtnl_unlock();
+       return err;
+}
+EXPORT_SYMBOL_GPL(rtnl_af_register);
+
+/**
+ * __rtnl_af_unregister - Unregister rtnl_af_ops from rtnetlink.
+ * @ops: struct rtnl_af_ops * to unregister
+ *
+ * The caller must hold the rtnl_mutex.
+ */
+void __rtnl_af_unregister(struct rtnl_af_ops *ops)
+{
+       list_del(&ops->list);
+}
+EXPORT_SYMBOL_GPL(__rtnl_af_unregister);
+
+/**
+ * rtnl_af_unregister - Unregister rtnl_af_ops from rtnetlink.
+ * @ops: struct rtnl_af_ops * to unregister
+ */
+void rtnl_af_unregister(struct rtnl_af_ops *ops)
+{
+       rtnl_lock();
+       __rtnl_af_unregister(ops);
+       rtnl_unlock();
+}
+EXPORT_SYMBOL_GPL(rtnl_af_unregister);
+
+static size_t rtnl_link_get_af_size(const struct net_device *dev)
+{
+       struct rtnl_af_ops *af_ops;
+       size_t size;
+
+       /* IFLA_AF_SPEC */
+       size = nla_total_size(sizeof(struct nlattr));
+
+       list_for_each_entry(af_ops, &rtnl_af_ops, list) {
+               if (af_ops->get_link_af_size) {
+                       /* AF_* + nested data */
+                       size += nla_total_size(sizeof(struct nlattr)) +
+                               af_ops->get_link_af_size(dev);
+               }
+       }
+
+       return size;
+}
+
 static int rtnl_link_fill(struct sk_buff *skb, const struct net_device *dev)
 {
        const struct rtnl_link_ops *ops = dev->rtnl_link_ops;
@@ -671,7 +760,8 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev)
               + nla_total_size(4) /* IFLA_NUM_VF */
               + rtnl_vfinfo_size(dev) /* IFLA_VFINFO_LIST */
               + rtnl_port_size(dev) /* IFLA_VF_PORTS + IFLA_PORT_SELF */
-              + rtnl_link_get_size(dev); /* IFLA_LINKINFO */
+              + rtnl_link_get_size(dev) /* IFLA_LINKINFO */
+              + rtnl_link_get_af_size(dev); /* IFLA_AF_SPEC */
 }
 
 static int rtnl_vf_ports_fill(struct sk_buff *skb, struct net_device *dev)
@@ -757,7 +847,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
        struct nlmsghdr *nlh;
        struct rtnl_link_stats64 temp;
        const struct rtnl_link_stats64 *stats;
-       struct nlattr *attr;
+       struct nlattr *attr, *af_spec;
+       struct rtnl_af_ops *af_ops;
 
        nlh = nlmsg_put(skb, pid, seq, type, sizeof(*ifm), flags);
        if (nlh == NULL)
@@ -866,6 +957,36 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
                        goto nla_put_failure;
        }
 
+       if (!(af_spec = nla_nest_start(skb, IFLA_AF_SPEC)))
+               goto nla_put_failure;
+
+       list_for_each_entry(af_ops, &rtnl_af_ops, list) {
+               if (af_ops->fill_link_af) {
+                       struct nlattr *af;
+                       int err;
+
+                       if (!(af = nla_nest_start(skb, af_ops->family)))
+                               goto nla_put_failure;
+
+                       err = af_ops->fill_link_af(skb, dev);
+
+                       /*
+                        * Caller may return ENODATA to indicate that there
+                        * was no data to be dumped. This is not an error, it
+                        * means we should trim the attribute header and
+                        * continue.
+                        */
+                       if (err == -ENODATA)
+                               nla_nest_cancel(skb, af);
+                       else if (err < 0)
+                               goto nla_put_failure;
+
+                       nla_nest_end(skb, af);
+               }
+       }
+
+       nla_nest_end(skb, af_spec);
+
        return nlmsg_end(skb, nlh);
 
 nla_put_failure:
@@ -924,6 +1045,7 @@ const struct nla_policy ifla_policy[IFLA_MAX+1] = {
        [IFLA_VFINFO_LIST]      = {. type = NLA_NESTED },
        [IFLA_VF_PORTS]         = { .type = NLA_NESTED },
        [IFLA_PORT_SELF]        = { .type = NLA_NESTED },
+       [IFLA_AF_SPEC]          = { .type = NLA_NESTED },
 };
 EXPORT_SYMBOL(ifla_policy);
 
@@ -1225,6 +1347,27 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
                        goto errout;
                modified = 1;
        }
+
+       if (tb[IFLA_AF_SPEC]) {
+               struct nlattr *af;
+               int rem;
+
+               nla_for_each_nested(af, tb[IFLA_AF_SPEC], rem) {
+                       const struct rtnl_af_ops *af_ops;
+
+                       if (!(af_ops = rtnl_af_lookup(nla_type(af))))
+                               continue;
+
+                       if (!af_ops->parse_link_af)
+                               continue;
+
+                       err = af_ops->parse_link_af(dev, af);
+                       if (err < 0)
+                               goto errout;
+
+                       modified = 1;
+               }
+       }
        err = 0;
 
 errout: