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>

include/net/dn_fib.h

 #ifndef _NET_DN_FIB_H
 #define _NET_DN_FIB_H
 
-/* WARNING: The ordering of these elements must match ordering
- *          of RTA_* rtnetlink attribute numbers.
- */
-struct dn_kern_rta {
-        void            *rta_dst;
-        void            *rta_src;
-        int             *rta_iif;
-        int             *rta_oif;
-        void            *rta_gw;
-        u32             *rta_priority;
-        void            *rta_prefsrc;
-        struct rtattr   *rta_mx;
-        struct rtattr   *rta_mp;
-        unsigned char   *rta_protoinfo;
-        u32             *rta_flow;
-        struct rta_cacheinfo *rta_ci;
-	struct rta_session *rta_sess;
-};
+#include <linux/netlink.h>
+
+extern const struct nla_policy rtm_dn_policy[];
 
 struct dn_fib_res {
 	struct fib_rule *r;
@@ -93,10 +78,10 @@ struct dn_fib_table {
 	u32 n;
 
 	int (*insert)(struct dn_fib_table *t, struct rtmsg *r, 
-			struct dn_kern_rta *rta, struct nlmsghdr *n, 
+			struct nlattr *attrs[], struct nlmsghdr *n,
 			struct netlink_skb_parms *req);
 	int (*delete)(struct dn_fib_table *t, struct rtmsg *r,
-			struct dn_kern_rta *rta, struct nlmsghdr *n,
+			struct nlattr *attrs[], struct nlmsghdr *n,
 			struct netlink_skb_parms *req);
 	int (*lookup)(struct dn_fib_table *t, const struct flowidn *fld,
 			struct dn_fib_res *res);
@@ -116,13 +101,12 @@ extern void dn_fib_cleanup(void);
 extern int dn_fib_ioctl(struct socket *sock, unsigned int cmd, 
 			unsigned long arg);
 extern struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, 
-				struct dn_kern_rta *rta, 
+				struct nlattr *attrs[],
 				const struct nlmsghdr *nlh, int *errp);
 extern int dn_fib_semantic_match(int type, struct dn_fib_info *fi, 
 			const struct flowidn *fld,
 			struct dn_fib_res *res);
 extern void dn_fib_release_info(struct dn_fib_info *fi);
-extern __le16 dn_fib_get_attr16(struct rtattr *attr, int attrlen, int type);
 extern void dn_fib_flush(void);
 extern void dn_fib_select_multipath(const struct flowidn *fld,
 					struct dn_fib_res *res);

net/decnet/dn_route.c

@@ -1619,17 +1619,21 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 portid, u32 seq,
 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);
 	}
 

net/decnet/dn_table.c

@@ -224,26 +224,27 @@ static struct dn_zone *dn_new_zone(struct dn_hash *table, int z)
 }
 
 
-static int dn_fib_nh_match(struct rtmsg *r, struct nlmsghdr *nlh, struct dn_kern_rta *rta, struct dn_fib_info *fi)
+static int dn_fib_nh_match(struct rtmsg *r, struct nlmsghdr *nlh, struct nlattr *attrs[], struct dn_fib_info *fi)
 {
 	struct rtnexthop *nhp;
 	int nhlen;
 
-	if (rta->rta_priority && *rta->rta_priority != fi->fib_priority)
+	if (attrs[RTA_PRIORITY] &&
+	    nla_get_u32(attrs[RTA_PRIORITY]) != fi->fib_priority)
 		return 1;
 
-	if (rta->rta_oif || rta->rta_gw) {
-		if ((!rta->rta_oif || *rta->rta_oif == fi->fib_nh->nh_oif) &&
-		    (!rta->rta_gw  || memcmp(rta->rta_gw, &fi->fib_nh->nh_gw, 2) == 0))
+	if (attrs[RTA_OIF] || attrs[RTA_GATEWAY]) {
+		if ((!attrs[RTA_OIF] || nla_get_u32(attrs[RTA_OIF]) == fi->fib_nh->nh_oif) &&
+		    (!attrs[RTA_GATEWAY]  || nla_get_le16(attrs[RTA_GATEWAY]) != fi->fib_nh->nh_gw))
 			return 0;
 		return 1;
 	}
 
-	if (rta->rta_mp == NULL)
+	if (!attrs[RTA_MULTIPATH])
 		return 0;
 
-	nhp = RTA_DATA(rta->rta_mp);
-	nhlen = RTA_PAYLOAD(rta->rta_mp);
+	nhp = nla_data(attrs[RTA_MULTIPATH]);
+	nhlen = nla_len(attrs[RTA_MULTIPATH]);
 
 	for_nexthops(fi) {
 		int attrlen = nhlen - sizeof(struct rtnexthop);
@@ -254,7 +255,10 @@ static int dn_fib_nh_match(struct rtmsg *r, struct nlmsghdr *nlh, struct dn_kern
 		if (nhp->rtnh_ifindex && nhp->rtnh_ifindex != nh->nh_oif)
 			return 1;
 		if (attrlen) {
-			gw = dn_fib_get_attr16(RTNH_DATA(nhp), attrlen, RTA_GATEWAY);
+			struct nlattr *gw_attr;
+
+			gw_attr = nla_find((struct nlattr *) (nhp + 1), attrlen, RTA_GATEWAY);
+			gw = gw_attr ? nla_get_le16(gw_attr) : 0;
 
 			if (gw && gw != nh->nh_gw)
 				return 1;
@@ -517,7 +521,8 @@ int dn_fib_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	return skb->len;
 }
 
-static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct dn_kern_rta *rta, struct nlmsghdr *n, struct netlink_skb_parms *req)
+static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct nlattr *attrs[],
+			       struct nlmsghdr *n, struct netlink_skb_parms *req)
 {
 	struct dn_hash *table = (struct dn_hash *)tb->data;
 	struct dn_fib_node *new_f, *f, **fp, **del_fp;
@@ -536,15 +541,14 @@ static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct
 		return -ENOBUFS;
 
 	dz_key_0(key);
-	if (rta->rta_dst) {
-		__le16 dst;
-		memcpy(&dst, rta->rta_dst, 2);
+	if (attrs[RTA_DST]) {
+		__le16 dst = nla_get_le16(attrs[RTA_DST]);
 		if (dst & ~DZ_MASK(dz))
 			return -EINVAL;
 		key = dz_key(dst, dz);
 	}
 
-	if ((fi = dn_fib_create_info(r, rta, n, &err)) == NULL)
+	if ((fi = dn_fib_create_info(r, attrs, n, &err)) == NULL)
 		return err;
 
 	if (dz->dz_nent > (dz->dz_divisor << 2) &&
@@ -654,7 +658,8 @@ static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct
 }
 
 
-static int dn_fib_table_delete(struct dn_fib_table *tb, struct rtmsg *r, struct dn_kern_rta *rta, struct nlmsghdr *n, struct netlink_skb_parms *req)
+static int dn_fib_table_delete(struct dn_fib_table *tb, struct rtmsg *r, struct nlattr *attrs[],
+			       struct nlmsghdr *n, struct netlink_skb_parms *req)
 {
 	struct dn_hash *table = (struct dn_hash*)tb->data;
 	struct dn_fib_node **fp, **del_fp, *f;
@@ -671,9 +676,8 @@ static int dn_fib_table_delete(struct dn_fib_table *tb, struct rtmsg *r, struct
 		return -ESRCH;
 
 	dz_key_0(key);
-	if (rta->rta_dst) {
-		__le16 dst;
-		memcpy(&dst, rta->rta_dst, 2);
+	if (attrs[RTA_DST]) {
+		__le16 dst = nla_get_le16(attrs[RTA_DST]);
 		if (dst & ~DZ_MASK(dz))
 			return -EINVAL;
 		key = dz_key(dst, dz);
@@ -703,7 +707,7 @@ static int dn_fib_table_delete(struct dn_fib_table *tb, struct rtmsg *r, struct
 				(r->rtm_scope == RT_SCOPE_NOWHERE || f->fn_scope == r->rtm_scope) &&
 				(!r->rtm_protocol ||
 					fi->fib_protocol == r->rtm_protocol) &&
-				dn_fib_nh_match(r, n, rta, fi) == 0)
+				dn_fib_nh_match(r, n, attrs, fi) == 0)
 			del_fp = fp;
 	}