decnet: Parse netlink attributes on our own

decnet is the only subsystem left that is relying on the global
netlink attribute buffer rta_buf. It's horrible design and we
want to get rid of it.

This converts all of decnet to do implicit attribute parsing. It
also gets rid of the error prone struct dn_kern_rta.

Yes, the fib_magic() stuff is not pretty.

It's compiled tested but I need someone with appropriate hardware
to test the patch since I don't have access to it.

Cc: linux-decnet-user@lists.sourceforge.net
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 11 deletions

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 5ac0e153ef83..b4b3508e77f0 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1619,17 +1619,21 @@ errout:
 static int dn_cache_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void *arg)
 {
         struct net *net = sock_net(in_skb->sk);
-        struct rtattr **rta = arg;
         struct rtmsg *rtm = nlmsg_data(nlh);
         struct dn_route *rt = NULL;
         struct dn_skb_cb *cb;
         int err;
         struct sk_buff *skb;
         struct flowidn fld;
+        struct nlattr *tb[RTA_MAX+1];
 
         if (!net_eq(net, &init_net))
                 return -EINVAL;
 
+        err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_dn_policy);
+        if (err < 0)
+                return err;
+
         memset(&fld, 0, sizeof(fld));
         fld.flowidn_proto = DNPROTO_NSP;
 
@@ -1639,12 +1643,14 @@ static int dn_cache_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void
         skb_reset_mac_header(skb);
         cb = DN_SKB_CB(skb);
 
-        if (rta[RTA_SRC-1])
-                memcpy(&fld.saddr, RTA_DATA(rta[RTA_SRC-1]), 2);
-        if (rta[RTA_DST-1])
-                memcpy(&fld.daddr, RTA_DATA(rta[RTA_DST-1]), 2);
-        if (rta[RTA_IIF-1])
-                memcpy(&fld.flowidn_iif, RTA_DATA(rta[RTA_IIF-1]), sizeof(int));
+        if (tb[RTA_SRC])
+                fld.saddr = nla_get_le16(tb[RTA_SRC]);
+
+        if (tb[RTA_DST])
+                fld.daddr = nla_get_le16(tb[RTA_DST]);
+
+        if (tb[RTA_IIF])
+                fld.flowidn_iif = nla_get_u32(tb[RTA_IIF]);
 
         if (fld.flowidn_iif) {
                 struct net_device *dev;
@@ -1669,10 +1675,9 @@ static int dn_cache_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, void
                 if (!err && -rt->dst.error)
                         err = rt->dst.error;
         } else {
-                int oif = 0;
-                if (rta[RTA_OIF - 1])
-                        memcpy(&oif, RTA_DATA(rta[RTA_OIF - 1]), sizeof(int));
-                fld.flowidn_oif = oif;
+                if (tb[RTA_OIF])
+                        fld.flowidn_oif = nla_get_u32(tb[RTA_OIF]);
+
                 err = dn_route_output_key((struct dst_entry **)&rt, &fld, 0);
         }