[RTNETLINK]: Link creation API

Add rtnetlink API for creating, changing and deleting software devices.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 409 insertions, 7 deletions

diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 604c2434f71c..3144babd2357 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -76,6 +76,8 @@ enum
 #define IFLA_WEIGHT IFLA_WEIGHT
         IFLA_OPERSTATE,
         IFLA_LINKMODE,
+        IFLA_LINKINFO,
+#define IFLA_LINKINFO IFLA_LINKINFO
         __IFLA_MAX
 };
 
@@ -140,4 +142,15 @@ struct ifla_cacheinfo
         __u32   retrans_time;
 };
 
+enum
+{
+        IFLA_INFO_UNSPEC,
+        IFLA_INFO_KIND,
+        IFLA_INFO_DATA,
+        IFLA_INFO_XSTATS,
+        __IFLA_INFO_MAX,
+};
+
+#define IFLA_INFO_MAX   (__IFLA_INFO_MAX - 1)
+
 #endif /* _LINUX_IF_LINK_H */
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 94cc77cd3aa3..e7913ee5581c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -540,6 +540,9 @@ struct net_device
         struct device           dev;
         /* space for optional statistics and wireless sysfs groups */
         struct attribute_group  *sysfs_groups[3];
+
+        /* rtnetlink link ops */
+        const struct rtnl_link_ops *rtnl_link_ops;
 };
 #define to_net_dev(d) container_of(d, struct net_device, dev)
 
diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index 3b3d4745618d..3861c05cdf0f 100644
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -22,4 +22,62 @@ static inline int rtnl_msg_family(struct nlmsghdr *nlh)
                 return AF_UNSPEC;
 }
 
+/**
+ *      struct rtnl_link_ops - rtnetlink link operations
+ *
+ *      @list: Used internally
+ *      @kind: Identifier
+ *      @maxtype: Highest device specific netlink attribute number
+ *      @policy: Netlink policy for device specific attribute validation
+ *      @validate: Optional validation function for netlink/changelink parameters
+ *      @priv_size: sizeof net_device private space
+ *      @setup: net_device setup function
+ *      @newlink: Function for configuring and registering a new device
+ *      @changelink: Function for changing parameters of an existing device
+ *      @dellink: Function to remove a device
+ *      @get_size: Function to calculate required room for dumping device
+ *                 specific netlink attributes
+ *      @fill_info: Function to dump device specific netlink attributes
+ *      @get_xstats_size: Function to calculate required room for dumping devic
+ *                        specific statistics
+ *      @fill_xstats: Function to dump device specific statistics
+ */
+struct rtnl_link_ops {
+        struct list_head        list;
+
+        const char              *kind;
+
+        size_t                  priv_size;
+        void                    (*setup)(struct net_device *dev);
+
+        int                     maxtype;
+        const struct nla_policy *policy;
+        int                     (*validate)(struct nlattr *tb[],
+                                            struct nlattr *data[]);
+
+        int                     (*newlink)(struct net_device *dev,
+                                           struct nlattr *tb[],
+                                           struct nlattr *data[]);
+        int                     (*changelink)(struct net_device *dev,
+                                              struct nlattr *tb[],
+                                              struct nlattr *data[]);
+        void                    (*dellink)(struct net_device *dev);
+
+        size_t                  (*get_size)(const struct net_device *dev);
+        int                     (*fill_info)(struct sk_buff *skb,
+                                             const struct net_device *dev);
+
+        size_t                  (*get_xstats_size)(const struct net_device *dev);
+        int                     (*fill_xstats)(struct sk_buff *skb,
+                                               const struct net_device *dev);
+};
+
+extern int      __rtnl_link_register(struct rtnl_link_ops *ops);
+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);
+
+#define MODULE_ALIAS_RTNL_LINK(kind) MODULE_ALIAS("rtnl-link-" kind)
+
 #endif
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 25ca219154e0..06c0c5afabf0 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -243,6 +243,143 @@ void rtnl_unregister_all(int protocol)
 
 EXPORT_SYMBOL_GPL(rtnl_unregister_all);
 
+static LIST_HEAD(link_ops);
+
+/**
+ * __rtnl_link_register - Register rtnl_link_ops with rtnetlink.
+ * @ops: struct rtnl_link_ops * to register
+ *
+ * The caller must hold the rtnl_mutex. This function should be used
+ * by drivers that create devices during module initialization. It
+ * must be called before registering the devices.
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int __rtnl_link_register(struct rtnl_link_ops *ops)
+{
+        list_add_tail(&ops->list, &link_ops);
+        return 0;
+}
+
+EXPORT_SYMBOL_GPL(__rtnl_link_register);
+
+/**
+ * rtnl_link_register - Register rtnl_link_ops with rtnetlink.
+ * @ops: struct rtnl_link_ops * to register
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int rtnl_link_register(struct rtnl_link_ops *ops)
+{
+        int err;
+
+        rtnl_lock();
+        err = __rtnl_link_register(ops);
+        rtnl_unlock();
+        return err;
+}
+
+EXPORT_SYMBOL_GPL(rtnl_link_register);
+
+/**
+ * __rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.
+ * @ops: struct rtnl_link_ops * to unregister
+ *
+ * The caller must hold the rtnl_mutex. This function should be used
+ * by drivers that unregister devices during module unloading. It must
+ * be called after unregistering the devices.
+ */
+void __rtnl_link_unregister(struct rtnl_link_ops *ops)
+{
+        list_del(&ops->list);
+}
+
+EXPORT_SYMBOL_GPL(__rtnl_link_unregister);
+
+/**
+ * rtnl_link_unregister - Unregister rtnl_link_ops from rtnetlink.
+ * @ops: struct rtnl_link_ops * to unregister
+ */
+void rtnl_link_unregister(struct rtnl_link_ops *ops)
+{
+        rtnl_lock();
+        __rtnl_link_unregister(ops);
+        rtnl_unlock();
+}
+
+EXPORT_SYMBOL_GPL(rtnl_link_unregister);
+
+static const struct rtnl_link_ops *rtnl_link_ops_get(const char *kind)
+{
+        const struct rtnl_link_ops *ops;
+
+        list_for_each_entry(ops, &link_ops, list) {
+                if (!strcmp(ops->kind, kind))
+                        return ops;
+        }
+        return NULL;
+}
+
+static size_t rtnl_link_get_size(const struct net_device *dev)
+{
+        const struct rtnl_link_ops *ops = dev->rtnl_link_ops;
+        size_t size;
+
+        if (!ops)
+                return 0;
+
+        size = nlmsg_total_size(sizeof(struct nlattr)) + /* IFLA_LINKINFO */
+               nlmsg_total_size(strlen(ops->kind) + 1);  /* IFLA_INFO_KIND */
+
+        if (ops->get_size)
+                /* IFLA_INFO_DATA + nested data */
+                size += nlmsg_total_size(sizeof(struct nlattr)) +
+                        ops->get_size(dev);
+
+        if (ops->get_xstats_size)
+                size += ops->get_xstats_size(dev);      /* IFLA_INFO_XSTATS */
+
+        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;
+        struct nlattr *linkinfo, *data;
+        int err = -EMSGSIZE;
+
+        linkinfo = nla_nest_start(skb, IFLA_LINKINFO);
+        if (linkinfo == NULL)
+                goto out;
+
+        if (nla_put_string(skb, IFLA_INFO_KIND, ops->kind) < 0)
+                goto err_cancel_link;
+        if (ops->fill_xstats) {
+                err = ops->fill_xstats(skb, dev);
+                if (err < 0)
+                        goto err_cancel_link;
+        }
+        if (ops->fill_info) {
+                data = nla_nest_start(skb, IFLA_INFO_DATA);
+                if (data == NULL)
+                        goto err_cancel_link;
+                err = ops->fill_info(skb, dev);
+                if (err < 0)
+                        goto err_cancel_data;
+                nla_nest_end(skb, data);
+        }
+
+        nla_nest_end(skb, linkinfo);
+        return 0;
+
+err_cancel_data:
+        nla_nest_cancel(skb, data);
+err_cancel_link:
+        nla_nest_cancel(skb, linkinfo);
+out:
+        return err;
+}
+
 static const int rtm_min[RTM_NR_FAMILIES] =
 {
         [RTM_FAM(RTM_NEWLINK)]      = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
@@ -437,7 +574,7 @@ static void copy_rtnl_link_stats(struct rtnl_link_stats *a,
         a->tx_compressed = b->tx_compressed;
 };
 
-static inline size_t if_nlmsg_size(void)
+static inline size_t if_nlmsg_size(const struct net_device *dev)
 {
         return NLMSG_ALIGN(sizeof(struct ifinfomsg))
                + nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
@@ -452,7 +589,8 @@ static inline size_t if_nlmsg_size(void)
                + nla_total_size(4) /* IFLA_LINK */
                + nla_total_size(4) /* IFLA_MASTER */
                + nla_total_size(1) /* IFLA_OPERSTATE */
-               + nla_total_size(1); /* IFLA_LINKMODE */
+               + nla_total_size(1) /* IFLA_LINKMODE */
+               + rtnl_link_get_size(dev); /* IFLA_LINKINFO */
 }
 
 static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
@@ -522,6 +660,11 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
                 }
         }
 
+        if (dev->rtnl_link_ops) {
+                if (rtnl_link_fill(skb, dev) < 0)
+                        goto nla_put_failure;
+        }
+
         return nlmsg_end(skb, nlh);
 
 nla_put_failure:
@@ -553,6 +696,8 @@ cont:
 
 static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
         [IFLA_IFNAME]           = { .type = NLA_STRING, .len = IFNAMSIZ-1 },
+        [IFLA_ADDRESS]          = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
+        [IFLA_BROADCAST]        = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
         [IFLA_MAP]              = { .len = sizeof(struct rtnl_link_ifmap) },
         [IFLA_MTU]              = { .type = NLA_U32 },
         [IFLA_TXQLEN]           = { .type = NLA_U32 },
@@ -561,10 +706,15 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
         [IFLA_LINKMODE]         = { .type = NLA_U8 },
 };
 
+static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
+        [IFLA_INFO_KIND]        = { .type = NLA_STRING },
+        [IFLA_INFO_DATA]        = { .type = NLA_NESTED },
+};
+
 static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
-                      struct nlattr **tb, char *ifname)
+                      struct nlattr **tb, char *ifname, int modified)
 {
-        int modified = 0, send_addr_notify = 0;
+        int send_addr_notify = 0;
         int err;
 
         if (tb[IFLA_MAP]) {
@@ -729,13 +879,189 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
             nla_len(tb[IFLA_BROADCAST]) < dev->addr_len)
                 goto errout_dev;
 
-        err = do_setlink(dev, ifm, tb, ifname);
+        err = do_setlink(dev, ifm, tb, ifname, 0);
 errout_dev:
         dev_put(dev);
 errout:
         return err;
 }
 
+static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+{
+        const struct rtnl_link_ops *ops;
+        struct net_device *dev;
+        struct ifinfomsg *ifm;
+        char ifname[IFNAMSIZ];
+        struct nlattr *tb[IFLA_MAX+1];
+        int err;
+
+        err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy);
+        if (err < 0)
+                return err;
+
+        if (tb[IFLA_IFNAME])
+                nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
+
+        ifm = nlmsg_data(nlh);
+        if (ifm->ifi_index > 0)
+                dev = __dev_get_by_index(ifm->ifi_index);
+        else if (tb[IFLA_IFNAME])
+                dev = __dev_get_by_name(ifname);
+        else
+                return -EINVAL;
+
+        if (!dev)
+                return -ENODEV;
+
+        ops = dev->rtnl_link_ops;
+        if (!ops)
+                return -EOPNOTSUPP;
+
+        ops->dellink(dev);
+        return 0;
+}
+
+static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+{
+        const struct rtnl_link_ops *ops;
+        struct net_device *dev;
+        struct ifinfomsg *ifm;
+        char kind[MODULE_NAME_LEN];
+        char ifname[IFNAMSIZ];
+        struct nlattr *tb[IFLA_MAX+1];
+        struct nlattr *linkinfo[IFLA_INFO_MAX+1];
+        int err;
+
+replay:
+        err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy);
+        if (err < 0)
+                return err;
+
+        if (tb[IFLA_IFNAME])
+                nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
+        else
+                ifname[0] = '\0';
+
+        ifm = nlmsg_data(nlh);
+        if (ifm->ifi_index > 0)
+                dev = __dev_get_by_index(ifm->ifi_index);
+        else if (ifname[0])
+                dev = __dev_get_by_name(ifname);
+        else
+                dev = NULL;
+
+        if (tb[IFLA_LINKINFO]) {
+                err = nla_parse_nested(linkinfo, IFLA_INFO_MAX,
+                                       tb[IFLA_LINKINFO], ifla_info_policy);
+                if (err < 0)
+                        return err;
+        } else
+                memset(linkinfo, 0, sizeof(linkinfo));
+
+        if (linkinfo[IFLA_INFO_KIND]) {
+                nla_strlcpy(kind, linkinfo[IFLA_INFO_KIND], sizeof(kind));
+                ops = rtnl_link_ops_get(kind);
+        } else {
+                kind[0] = '\0';
+                ops = NULL;
+        }
+
+        if (1) {
+                struct nlattr *attr[ops ? ops->maxtype + 1 : 0], **data = NULL;
+
+                if (ops) {
+                        if (ops->maxtype && linkinfo[IFLA_INFO_DATA]) {
+                                err = nla_parse_nested(attr, ops->maxtype,
+                                                       linkinfo[IFLA_INFO_DATA],
+                                                       ops->policy);
+                                if (err < 0)
+                                        return err;
+                                data = attr;
+                        }
+                        if (ops->validate) {
+                                err = ops->validate(tb, data);
+                                if (err < 0)
+                                        return err;
+                        }
+                }
+
+                if (dev) {
+                        int modified = 0;
+
+                        if (nlh->nlmsg_flags & NLM_F_EXCL)
+                                return -EEXIST;
+                        if (nlh->nlmsg_flags & NLM_F_REPLACE)
+                                return -EOPNOTSUPP;
+
+                        if (linkinfo[IFLA_INFO_DATA]) {
+                                if (!ops || ops != dev->rtnl_link_ops ||
+                                    !ops->changelink)
+                                        return -EOPNOTSUPP;
+
+                                err = ops->changelink(dev, tb, data);
+                                if (err < 0)
+                                        return err;
+                                modified = 1;
+                        }
+
+                        return do_setlink(dev, ifm, tb, ifname, modified);
+                }
+
+                if (!(nlh->nlmsg_flags & NLM_F_CREATE))
+                        return -ENODEV;
+
+                if (ifm->ifi_index || ifm->ifi_flags || ifm->ifi_change)
+                        return -EOPNOTSUPP;
+                if (tb[IFLA_ADDRESS] || tb[IFLA_BROADCAST] || tb[IFLA_MAP] ||
+                    tb[IFLA_MASTER] || tb[IFLA_PROTINFO])
+                        return -EOPNOTSUPP;
+
+                if (!ops) {
+#ifdef CONFIG_KMOD
+                        if (kind[0]) {
+                                __rtnl_unlock();
+                                request_module("rtnl-link-%s", kind);
+                                rtnl_lock();
+                                ops = rtnl_link_ops_get(kind);
+                                if (ops)
+                                        goto replay;
+                        }
+#endif
+                        return -EOPNOTSUPP;
+                }
+
+                if (!ifname[0])
+                        snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind);
+                dev = alloc_netdev(ops->priv_size, ifname, ops->setup);
+                if (!dev)
+                        return -ENOMEM;
+
+                if (strchr(dev->name, '%')) {
+                        err = dev_alloc_name(dev, dev->name);
+                        if (err < 0)
+                                goto err_free;
+                }
+                dev->rtnl_link_ops = ops;
+
+                if (tb[IFLA_MTU])
+                        dev->mtu = nla_get_u32(tb[IFLA_MTU]);
+                if (tb[IFLA_TXQLEN])
+                        dev->tx_queue_len = nla_get_u32(tb[IFLA_TXQLEN]);
+                if (tb[IFLA_WEIGHT])
+                        dev->weight = nla_get_u32(tb[IFLA_WEIGHT]);
+                if (tb[IFLA_OPERSTATE])
+                        set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
+                if (tb[IFLA_LINKMODE])
+                        dev->link_mode = nla_get_u8(tb[IFLA_LINKMODE]);
+
+                err = ops->newlink(dev, tb, data);
+err_free:
+                if (err < 0)
+                        free_netdev(dev);
+                return err;
+        }
+}
+
 static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
         struct ifinfomsg *ifm;
@@ -756,7 +1082,7 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
         } else
                 return -EINVAL;
 
-        nskb = nlmsg_new(if_nlmsg_size(), GFP_KERNEL);
+        nskb = nlmsg_new(if_nlmsg_size(dev), GFP_KERNEL);
         if (nskb == NULL) {
                 err = -ENOBUFS;
                 goto errout;
@@ -806,7 +1132,7 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change)
         struct sk_buff *skb;
         int err = -ENOBUFS;
 
-        skb = nlmsg_new(if_nlmsg_size(), GFP_KERNEL);
+        skb = nlmsg_new(if_nlmsg_size(dev), GFP_KERNEL);
         if (skb == NULL)
                 goto errout;
 
@@ -961,6 +1287,8 @@ void __init rtnetlink_init(void)
 
         rtnl_register(PF_UNSPEC, RTM_GETLINK, rtnl_getlink, rtnl_dump_ifinfo);
         rtnl_register(PF_UNSPEC, RTM_SETLINK, rtnl_setlink, NULL);
+        rtnl_register(PF_UNSPEC, RTM_NEWLINK, rtnl_newlink, NULL);
+        rtnl_register(PF_UNSPEC, RTM_DELLINK, rtnl_dellink, NULL);
 
         rtnl_register(PF_UNSPEC, RTM_GETADDR, NULL, rtnl_dump_all);
         rtnl_register(PF_UNSPEC, RTM_GETROUTE, NULL, rtnl_dump_all);