neighbour: register rtnl doit handler

this patch registers neigh doit handler. The doit handler
returns a neigh entry given dst and dev. This is similar
to route and fdb doit (get) handlers. Also moves nda_policy
declaration from rtnetlink.c to neighbour.c

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Reviewed-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 194 insertions, 23 deletions

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 66221f1991c0..7c1ab9edba03 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -255,6 +255,7 @@ static inline void *neighbour_priv(const struct neighbour *n)
 #define NEIGH_UPDATE_F_ISROUTER                 0x40000000
 #define NEIGH_UPDATE_F_ADMIN                    0x80000000
 
+extern const struct nla_policy nda_policy[];
 
 static inline bool neigh_key_eq16(const struct neighbour *n, const void *pkey)
 {
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index fb4372cb1de1..43687c9abe1d 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1751,6 +1751,18 @@ static struct neigh_table *neigh_find_table(int family)
         return tbl;
 }
 
+const struct nla_policy nda_policy[NDA_MAX+1] = {
+        [NDA_DST]               = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
+        [NDA_LLADDR]            = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
+        [NDA_CACHEINFO]         = { .len = sizeof(struct nda_cacheinfo) },
+        [NDA_PROBES]            = { .type = NLA_U32 },
+        [NDA_VLAN]              = { .type = NLA_U16 },
+        [NDA_PORT]              = { .type = NLA_U16 },
+        [NDA_VNI]               = { .type = NLA_U32 },
+        [NDA_IFINDEX]           = { .type = NLA_U32 },
+        [NDA_MASTER]            = { .type = NLA_U32 },
+};
+
 static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh,
                         struct netlink_ext_ack *extack)
 {
@@ -2711,6 +2723,186 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
         return skb->len;
 }
 
+static int neigh_valid_get_req(const struct nlmsghdr *nlh,
+                               struct neigh_table **tbl,
+                               void **dst, int *dev_idx, u8 *ndm_flags,
+                               struct netlink_ext_ack *extack)
+{
+        struct nlattr *tb[NDA_MAX + 1];
+        struct ndmsg *ndm;
+        int err, i;
+
+        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
+                NL_SET_ERR_MSG(extack, "Invalid header for neighbor get request");
+                return -EINVAL;
+        }
+
+        ndm = nlmsg_data(nlh);
+        if (ndm->ndm_pad1  || ndm->ndm_pad2  || ndm->ndm_state ||
+            ndm->ndm_type) {
+                NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor get request");
+                return -EINVAL;
+        }
+
+        if (ndm->ndm_flags & ~NTF_PROXY) {
+                NL_SET_ERR_MSG(extack, "Invalid flags in header for neighbor get request");
+                return -EINVAL;
+        }
+
+        err = nlmsg_parse_strict(nlh, sizeof(struct ndmsg), tb, NDA_MAX,
+                                 nda_policy, extack);
+        if (err < 0)
+                return err;
+
+        *ndm_flags = ndm->ndm_flags;
+        *dev_idx = ndm->ndm_ifindex;
+        *tbl = neigh_find_table(ndm->ndm_family);
+        if (*tbl == NULL) {
+                NL_SET_ERR_MSG(extack, "Unsupported family in header for neighbor get request");
+                return -EAFNOSUPPORT;
+        }
+
+        for (i = 0; i <= NDA_MAX; ++i) {
+                if (!tb[i])
+                        continue;
+
+                switch (i) {
+                case NDA_DST:
+                        if (nla_len(tb[i]) != (int)(*tbl)->key_len) {
+                                NL_SET_ERR_MSG(extack, "Invalid network address in neighbor get request");
+                                return -EINVAL;
+                        }
+                        *dst = nla_data(tb[i]);
+                        break;
+                default:
+                        NL_SET_ERR_MSG(extack, "Unsupported attribute in neighbor get request");
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
+static inline size_t neigh_nlmsg_size(void)
+{
+        return NLMSG_ALIGN(sizeof(struct ndmsg))
+               + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
+               + nla_total_size(MAX_ADDR_LEN) /* NDA_LLADDR */
+               + nla_total_size(sizeof(struct nda_cacheinfo))
+               + nla_total_size(4)  /* NDA_PROBES */
+               + nla_total_size(1); /* NDA_PROTOCOL */
+}
+
+static int neigh_get_reply(struct net *net, struct neighbour *neigh,
+                           u32 pid, u32 seq)
+{
+        struct sk_buff *skb;
+        int err = 0;
+
+        skb = nlmsg_new(neigh_nlmsg_size(), GFP_KERNEL);
+        if (!skb)
+                return -ENOBUFS;
+
+        err = neigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0);
+        if (err) {
+                kfree_skb(skb);
+                goto errout;
+        }
+
+        err = rtnl_unicast(skb, net, pid);
+errout:
+        return err;
+}
+
+static inline size_t pneigh_nlmsg_size(void)
+{
+        return NLMSG_ALIGN(sizeof(struct ndmsg))
+               + nla_total_size(MAX_ADDR_LEN); /* NDA_DST */
+               + nla_total_size(1); /* NDA_PROTOCOL */
+}
+
+static int pneigh_get_reply(struct net *net, struct pneigh_entry *neigh,
+                            u32 pid, u32 seq, struct neigh_table *tbl)
+{
+        struct sk_buff *skb;
+        int err = 0;
+
+        skb = nlmsg_new(pneigh_nlmsg_size(), GFP_KERNEL);
+        if (!skb)
+                return -ENOBUFS;
+
+        err = pneigh_fill_info(skb, neigh, pid, seq, RTM_NEWNEIGH, 0, tbl);
+        if (err) {
+                kfree_skb(skb);
+                goto errout;
+        }
+
+        err = rtnl_unicast(skb, net, pid);
+errout:
+        return err;
+}
+
+static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
+                     struct netlink_ext_ack *extack)
+{
+        struct net *net = sock_net(in_skb->sk);
+        struct net_device *dev = NULL;
+        struct neigh_table *tbl = NULL;
+        struct neighbour *neigh;
+        void *dst = NULL;
+        u8 ndm_flags = 0;
+        int dev_idx = 0;
+        int err;
+
+        err = neigh_valid_get_req(nlh, &tbl, &dst, &dev_idx, &ndm_flags,
+                                  extack);
+        if (err < 0)
+                return err;
+
+        if (dev_idx) {
+                dev = __dev_get_by_index(net, dev_idx);
+                if (!dev) {
+                        NL_SET_ERR_MSG(extack, "Unknown device ifindex");
+                        return -ENODEV;
+                }
+        }
+
+        if (!dst) {
+                NL_SET_ERR_MSG(extack, "Network address not specified");
+                return -EINVAL;
+        }
+
+        if (ndm_flags & NTF_PROXY) {
+                struct pneigh_entry *pn;
+
+                pn = pneigh_lookup(tbl, net, dst, dev, 0);
+                if (!pn) {
+                        NL_SET_ERR_MSG(extack, "Proxy neighbour entry not found");
+                        return -ENOENT;
+                }
+                return pneigh_get_reply(net, pn, NETLINK_CB(in_skb).portid,
+                                        nlh->nlmsg_seq, tbl);
+        }
+
+        if (!dev) {
+                NL_SET_ERR_MSG(extack, "No device specified");
+                return -EINVAL;
+        }
+
+        neigh = neigh_lookup(tbl, dst, dev);
+        if (!neigh) {
+                NL_SET_ERR_MSG(extack, "Neighbour entry not found");
+                return -ENOENT;
+        }
+
+        err = neigh_get_reply(net, neigh, NETLINK_CB(in_skb).portid,
+                              nlh->nlmsg_seq);
+
+        neigh_release(neigh);
+
+        return err;
+}
+
 void neigh_for_each(struct neigh_table *tbl, void (*cb)(struct neighbour *, void *), void *cookie)
 {
         int chain;
@@ -3118,16 +3310,6 @@ static const struct seq_operations neigh_stat_seq_ops = {
 };
 #endif /* CONFIG_PROC_FS */
 
-static inline size_t neigh_nlmsg_size(void)
-{
-        return NLMSG_ALIGN(sizeof(struct ndmsg))
-               + nla_total_size(MAX_ADDR_LEN) /* NDA_DST */
-               + nla_total_size(MAX_ADDR_LEN) /* NDA_LLADDR */
-               + nla_total_size(sizeof(struct nda_cacheinfo))
-               + nla_total_size(4)  /* NDA_PROBES */
-               + nla_total_size(1); /* NDA_PROTOCOL */
-}
-
 static void __neigh_notify(struct neighbour *n, int type, int flags,
                            u32 pid)
 {
@@ -3511,7 +3693,7 @@ static int __init neigh_init(void)
 {
         rtnl_register(PF_UNSPEC, RTM_NEWNEIGH, neigh_add, NULL, 0);
         rtnl_register(PF_UNSPEC, RTM_DELNEIGH, neigh_delete, NULL, 0);
-        rtnl_register(PF_UNSPEC, RTM_GETNEIGH, NULL, neigh_dump_info, 0);
+        rtnl_register(PF_UNSPEC, RTM_GETNEIGH, neigh_get, neigh_dump_info, 0);
 
         rtnl_register(PF_UNSPEC, RTM_GETNEIGHTBL, NULL, neightbl_dump_info,
                       0);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index baf2685b4da2..48f61885fd6f 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3460,18 +3460,6 @@ void rtmsg_ifinfo_newnet(int type, struct net_device *dev, unsigned int change,
                            new_nsid, new_ifindex);
 }
 
-static const struct nla_policy nda_policy[NDA_MAX+1] = {
-        [NDA_DST]               = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
-        [NDA_LLADDR]            = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
-        [NDA_CACHEINFO]         = { .len = sizeof(struct nda_cacheinfo) },
-        [NDA_PROBES]            = { .type = NLA_U32 },
-        [NDA_VLAN]              = { .type = NLA_U16 },
-        [NDA_PORT]              = { .type = NLA_U16 },
-        [NDA_VNI]               = { .type = NLA_U32 },
-        [NDA_IFINDEX]           = { .type = NLA_U32 },
-        [NDA_MASTER]            = { .type = NLA_U32 },
-};
-
 static int nlmsg_populate_fdb_fill(struct sk_buff *skb,
                                    struct net_device *dev,
                                    u8 *addr, u16 vid, u32 pid, u32 seq,