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, 115 insertions, 96 deletions

diff --git a/net/decnet/dn_fib.c b/net/decnet/dn_fib.c
index e36614e..42a8048 100644
--- a/net/decnet/dn_fib.c
+++ b/net/decnet/dn_fib.c
@@ -145,22 +145,10 @@ static inline struct dn_fib_info *dn_fib_find_info(const struct dn_fib_info *nfi
 	return NULL;
 }
 
-__le16 dn_fib_get_attr16(struct rtattr *attr, int attrlen, int type)
+static int dn_fib_count_nhs(const struct nlattr *attr)
 {
-	while(RTA_OK(attr,attrlen)) {
-		if (attr->rta_type == type)
-			return *(__le16*)RTA_DATA(attr);
-		attr = RTA_NEXT(attr, attrlen);
-	}
-
-	return 0;
-}
-
-static int dn_fib_count_nhs(struct rtattr *rta)
-{
-	int nhs = 0;
-	struct rtnexthop *nhp = RTA_DATA(rta);
-	int nhlen = RTA_PAYLOAD(rta);
+	struct rtnexthop *nhp = nla_data(attr);
+	int nhs = 0, nhlen = nla_len(attr);
 
 	while(nhlen >= (int)sizeof(struct rtnexthop)) {
 		if ((nhlen -= nhp->rtnh_len) < 0)
@@ -172,10 +160,11 @@ static int dn_fib_count_nhs(struct rtattr *rta)
 	return nhs;
 }
 
-static int dn_fib_get_nhs(struct dn_fib_info *fi, const struct rtattr *rta, const struct rtmsg *r)
+static int dn_fib_get_nhs(struct dn_fib_info *fi, const struct nlattr *attr,
+			  const struct rtmsg *r)
 {
-	struct rtnexthop *nhp = RTA_DATA(rta);
-	int nhlen = RTA_PAYLOAD(rta);
+	struct rtnexthop *nhp = nla_data(attr);
+	int nhlen = nla_len(attr);
 
 	change_nexthops(fi) {
 		int attrlen = nhlen - sizeof(struct rtnexthop);
@@ -187,7 +176,10 @@ static int dn_fib_get_nhs(struct dn_fib_info *fi, const struct rtattr *rta, cons
 		nh->nh_weight = nhp->rtnh_hops + 1;
 
 		if (attrlen) {
-			nh->nh_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);
+			nh->nh_gw = gw_attr ? nla_get_le16(gw_attr) : 0;
 		}
 		nhp = RTNH_NEXT(nhp);
 	} endfor_nexthops(fi);
@@ -268,7 +260,8 @@ out:
 }
 
 
-struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta *rta, const struct nlmsghdr *nlh, int *errp)
+struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct nlattr *attrs[],
+				       const struct nlmsghdr *nlh, int *errp)
 {
 	int err;
 	struct dn_fib_info *fi = NULL;
@@ -281,11 +274,9 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta
 	if (dn_fib_props[r->rtm_type].scope > r->rtm_scope)
 		goto err_inval;
 
-	if (rta->rta_mp) {
-		nhs = dn_fib_count_nhs(rta->rta_mp);
-		if (nhs == 0)
-			goto err_inval;
-	}
+	if (attrs[RTA_MULTIPATH] &&
+	    (nhs = dn_fib_count_nhs(attrs[RTA_MULTIPATH])) == 0)
+		goto err_inval;
 
 	fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct dn_fib_nh), GFP_KERNEL);
 	err = -ENOBUFS;
@@ -295,53 +286,65 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta
 	fi->fib_protocol = r->rtm_protocol;
 	fi->fib_nhs = nhs;
 	fi->fib_flags = r->rtm_flags;
-	if (rta->rta_priority)
-		fi->fib_priority = *rta->rta_priority;
-	if (rta->rta_mx) {
-		int attrlen = RTA_PAYLOAD(rta->rta_mx);
-		struct rtattr *attr = RTA_DATA(rta->rta_mx);
 
-		while(RTA_OK(attr, attrlen)) {
-			unsigned int flavour = attr->rta_type;
+	if (attrs[RTA_PRIORITY])
+		fi->fib_priority = nla_get_u32(attrs[RTA_PRIORITY]);
+
+	if (attrs[RTA_METRICS]) {
+		struct nlattr *attr;
+		int rem;
 
-			if (flavour) {
-				if (flavour > RTAX_MAX)
+		nla_for_each_nested(attr, attrs[RTA_METRICS], rem) {
+			int type = nla_type(attr);
+
+			if (type) {
+				if (type > RTAX_MAX || nla_len(attr) < 4)
 					goto err_inval;
-				fi->fib_metrics[flavour-1] = *(unsigned int *)RTA_DATA(attr);
+
+				fi->fib_metrics[type-1] = nla_get_u32(attr);
 			}
-			attr = RTA_NEXT(attr, attrlen);
 		}
 	}
-	if (rta->rta_prefsrc)
-		memcpy(&fi->fib_prefsrc, rta->rta_prefsrc, 2);
 
-	if (rta->rta_mp) {
-		if ((err = dn_fib_get_nhs(fi, rta->rta_mp, r)) != 0)
+	if (attrs[RTA_PREFSRC])
+		fi->fib_prefsrc = nla_get_le16(attrs[RTA_PREFSRC]);
+
+	if (attrs[RTA_MULTIPATH]) {
+		if ((err = dn_fib_get_nhs(fi, attrs[RTA_MULTIPATH], r)) != 0)
 			goto failure;
-		if (rta->rta_oif && fi->fib_nh->nh_oif != *rta->rta_oif)
+
+		if (attrs[RTA_OIF] &&
+		    fi->fib_nh->nh_oif != nla_get_u32(attrs[RTA_OIF]))
 			goto err_inval;
-		if (rta->rta_gw && memcmp(&fi->fib_nh->nh_gw, rta->rta_gw, 2))
+
+		if (attrs[RTA_GATEWAY] &&
+		    fi->fib_nh->nh_gw != nla_get_le16(attrs[RTA_GATEWAY]))
 			goto err_inval;
 	} else {
 		struct dn_fib_nh *nh = fi->fib_nh;
-		if (rta->rta_oif)
-			nh->nh_oif = *rta->rta_oif;
-		if (rta->rta_gw)
-			memcpy(&nh->nh_gw, rta->rta_gw, 2);
+
+		if (attrs[RTA_OIF])
+			nh->nh_oif = nla_get_u32(attrs[RTA_OIF]);
+
+		if (attrs[RTA_GATEWAY])
+			nh->nh_gw = nla_get_le16(attrs[RTA_GATEWAY]);
+
 		nh->nh_flags = r->rtm_flags;
 		nh->nh_weight = 1;
 	}
 
 	if (r->rtm_type == RTN_NAT) {
-		if (rta->rta_gw == NULL || nhs != 1 || rta->rta_oif)
+		if (!attrs[RTA_GATEWAY] || nhs != 1 || attrs[RTA_OIF])
 			goto err_inval;
-		memcpy(&fi->fib_nh->nh_gw, rta->rta_gw, 2);
+
+		fi->fib_nh->nh_gw = nla_get_le16(attrs[RTA_GATEWAY]);
 		goto link_it;
 	}
 
 	if (dn_fib_props[r->rtm_type].error) {
-		if (rta->rta_gw || rta->rta_oif || rta->rta_mp)
+		if (attrs[RTA_GATEWAY] || attrs[RTA_OIF] || attrs[RTA_MULTIPATH])
 			goto err_inval;
+
 		goto link_it;
 	}
 
@@ -367,8 +370,8 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta
 	}
 
 	if (fi->fib_prefsrc) {
-		if (r->rtm_type != RTN_LOCAL || rta->rta_dst == NULL ||
-		    memcmp(&fi->fib_prefsrc, rta->rta_dst, 2))
+		if (r->rtm_type != RTN_LOCAL || !attrs[RTA_DST] ||
+		    fi->fib_prefsrc != nla_get_le16(attrs[RTA_DST]))
 			if (dnet_addr_type(fi->fib_prefsrc) != RTN_LOCAL)
 				goto err_inval;
 	}
@@ -486,29 +489,24 @@ void dn_fib_select_multipath(const struct flowidn *fld, struct dn_fib_res *res)
 	spin_unlock_bh(&dn_fib_multipath_lock);
 }
 
+const struct nla_policy rtm_dn_policy[RTA_MAX + 1] = {
+	[RTA_DST]		= { .type = NLA_U16 },
+	[RTA_SRC]		= { .type = NLA_U16 },
+	[RTA_IIF]		= { .type = NLA_U32 },
+	[RTA_OIF]		= { .type = NLA_U32 },
+	[RTA_GATEWAY]		= { .type = NLA_U16 },
+	[RTA_PRIORITY]		= { .type = NLA_U32 },
+	[RTA_PREFSRC]		= { .type = NLA_U16 },
+	[RTA_METRICS]		= { .type = NLA_NESTED },
+	[RTA_MULTIPATH]		= { .type = NLA_NESTED },
+	[RTA_TABLE]		= { .type = NLA_U32 },
+	[RTA_MARK]		= { .type = NLA_U32 },
+};
 
-static int dn_fib_check_attr(struct rtmsg *r, struct rtattr **rta)
-{
-	int i;
-
-	for(i = 1; i <= RTA_MAX; i++) {
-		struct rtattr *attr = rta[i-1];
-		if (attr) {
-			if (RTA_PAYLOAD(attr) < 4 && RTA_PAYLOAD(attr) != 2)
-				return -EINVAL;
-			if (i != RTA_MULTIPATH && i != RTA_METRICS &&
-			    i != RTA_TABLE)
-				rta[i-1] = (struct rtattr *)RTA_DATA(attr);
-		}
-	}
-
-	return 0;
-}
-
-static inline u32 rtm_get_table(struct rtattr **rta, u8 table)
+static inline u32 rtm_get_table(struct nlattr *attrs[], u8 table)
 {
-	if (rta[RTA_TABLE - 1])
-		table = nla_get_u32((struct nlattr *) rta[RTA_TABLE - 1]);
+	if (attrs[RTA_TABLE])
+		table = nla_get_u32(attrs[RTA_TABLE]);
 
 	return table;
 }
@@ -517,8 +515,9 @@ static int dn_fib_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *
 {
 	struct net *net = sock_net(skb->sk);
 	struct dn_fib_table *tb;
-	struct rtattr **rta = arg;
-	struct rtmsg *r = NLMSG_DATA(nlh);
+	struct rtmsg *r = nlmsg_data(nlh);
+	struct nlattr *attrs[RTA_MAX+1];
+	int err;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -526,22 +525,24 @@ static int dn_fib_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *
 	if (!net_eq(net, &init_net))
 		return -EINVAL;
 
-	if (dn_fib_check_attr(r, rta))
-		return -EINVAL;
+	err = nlmsg_parse(nlh, sizeof(*r), attrs, RTA_MAX, rtm_dn_policy);
+	if (err < 0)
+		return err;
 
-	tb = dn_fib_get_table(rtm_get_table(rta, r->rtm_table), 0);
-	if (tb)
-		return tb->delete(tb, r, (struct dn_kern_rta *)rta, nlh, &NETLINK_CB(skb));
+	tb = dn_fib_get_table(rtm_get_table(attrs, r->rtm_table), 0);
+	if (!tb)
+		return -ESRCH;
 
-	return -ESRCH;
+	return tb->delete(tb, r, attrs, nlh, &NETLINK_CB(skb));
 }
 
 static int dn_fib_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 {
 	struct net *net = sock_net(skb->sk);
 	struct dn_fib_table *tb;
-	struct rtattr **rta = arg;
-	struct rtmsg *r = NLMSG_DATA(nlh);
+	struct rtmsg *r = nlmsg_data(nlh);
+	struct nlattr *attrs[RTA_MAX+1];
+	int err;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
@@ -549,14 +550,15 @@ static int dn_fib_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh, void *
 	if (!net_eq(net, &init_net))
 		return -EINVAL;
 
-	if (dn_fib_check_attr(r, rta))
-		return -EINVAL;
+	err = nlmsg_parse(nlh, sizeof(*r), attrs, RTA_MAX, rtm_dn_policy);
+	if (err < 0)
+		return err;
 
-	tb = dn_fib_get_table(rtm_get_table(rta, r->rtm_table), 1);
-	if (tb)
-		return tb->insert(tb, r, (struct dn_kern_rta *)rta, nlh, &NETLINK_CB(skb));
+	tb = dn_fib_get_table(rtm_get_table(attrs, r->rtm_table), 1);
+	if (!tb)
+		return -ENOBUFS;
 
-	return -ENOBUFS;
+	return tb->insert(tb, r, attrs, nlh, &NETLINK_CB(skb));
 }
 
 static void fib_magic(int cmd, int type, __le16 dst, int dst_len, struct dn_ifaddr *ifa)
@@ -566,10 +568,31 @@ static void fib_magic(int cmd, int type, __le16 dst, int dst_len, struct dn_ifad
 		struct nlmsghdr nlh;
 		struct rtmsg rtm;
 	} req;
-	struct dn_kern_rta rta;
+	struct {
+		struct nlattr hdr;
+		__le16 dst;
+	} dst_attr = {
+		.dst = dst,
+	};
+	struct {
+		struct nlattr hdr;
+		__le16 prefsrc;
+	} prefsrc_attr = {
+		.prefsrc = ifa->ifa_local,
+	};
+	struct {
+		struct nlattr hdr;
+		u32 oif;
+	} oif_attr = {
+		.oif = ifa->ifa_dev->dev->ifindex,
+	};
+	struct nlattr *attrs[RTA_MAX+1] = {
+		[RTA_DST] = (struct nlattr *) &dst_attr,
+		[RTA_PREFSRC] = (struct nlattr * ) &prefsrc_attr,
+		[RTA_OIF] = (struct nlattr *) &oif_attr,
+	};
 
 	memset(&req.rtm, 0, sizeof(req.rtm));
-	memset(&rta, 0, sizeof(rta));
 
 	if (type == RTN_UNICAST)
 		tb = dn_fib_get_table(RT_MIN_TABLE, 1);
@@ -591,14 +614,10 @@ static void fib_magic(int cmd, int type, __le16 dst, int dst_len, struct dn_ifad
 	req.rtm.rtm_scope = (type != RTN_LOCAL ? RT_SCOPE_LINK : RT_SCOPE_HOST);
 	req.rtm.rtm_type = type;
 
-	rta.rta_dst = &dst;
-	rta.rta_prefsrc = &ifa->ifa_local;
-	rta.rta_oif = &ifa->ifa_dev->dev->ifindex;
-
 	if (cmd == RTM_NEWROUTE)
-		tb->insert(tb, &req.rtm, &rta, &req.nlh, NULL);
+		tb->insert(tb, &req.rtm, attrs, &req.nlh, NULL);
 	else
-		tb->delete(tb, &req.rtm, &rta, &req.nlh, NULL);
+		tb->delete(tb, &req.rtm, attrs, &req.nlh, NULL);
 }
 
 static void dn_fib_add_ifaddr(struct dn_ifaddr *ifa)