net: ipv4: Convert inet_rtm_getroute to rcu versions of route lookup

Convert inet_rtm_getroute to use ip_route_input_rcu and
ip_route_output_key_hash_rcu passing the fib_result arg to both.
The rcu lock is held through the creation of the response, so the
rtable/dst does not need to be attached to the skb and is passed
to rt_fill_info directly.

In converting from ip_route_output_key to ip_route_output_key_hash_rcu
the xfrm_lookup_route in ip_route_output_flow is dropped since
flowi4_proto is not set for a route get request.

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

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d8fcecce3839cc351caa00787cdc986009f47fbf..1fa9127ec4db4d3b960652982b40476c56a4ead7 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2534,11 +2534,11 @@ struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
 }
 EXPORT_SYMBOL_GPL(ip_route_output_flow);
 
+/* called with rcu_read_lock held */
 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
                        struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
-                       u32 seq)
+                       u32 seq, struct rtable *rt)
 {
-       struct rtable *rt = skb_rtable(skb);
        struct rtmsg *r;
        struct nlmsghdr *nlh;
        unsigned long expires = 0;
@@ -2653,6 +2653,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        struct net *net = sock_net(in_skb->sk);
        struct rtmsg *rtm;
        struct nlattr *tb[RTA_MAX+1];
+       struct fib_result res = {};
        struct rtable *rt = NULL;
        struct flowi4 fl4;
        __be32 dst = 0;
@@ -2709,10 +2710,12 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        fl4.flowi4_mark = mark;
        fl4.flowi4_uid = uid;
 
+       rcu_read_lock();
+
        if (iif) {
                struct net_device *dev;
 
-               dev = __dev_get_by_index(net, iif);
+               dev = dev_get_by_index_rcu(net, iif);
                if (!dev) {
                        err = -ENODEV;
                        goto errout_free;
@@ -2721,14 +2724,14 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                skb->protocol   = htons(ETH_P_IP);
                skb->dev        = dev;
                skb->mark       = mark;
-               err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
+               err = ip_route_input_rcu(skb, dst, src, rtm->rtm_tos,
+                                        dev, &res);
 
                rt = skb_rtable(skb);
                if (err == 0 && rt->dst.error)
                        err = -rt->dst.error;
        } else {
-               rt = ip_route_output_key(net, &fl4);
-
+               rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
                err = 0;
                if (IS_ERR(rt))
                        err = PTR_ERR(rt);
@@ -2737,7 +2740,6 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        if (err)
                goto errout_free;
 
-       skb_dst_set(skb, &rt->dst);
        if (rtm->rtm_flags & RTM_F_NOTIFY)
                rt->rt_flags |= RTCF_NOTIFY;
 
@@ -2745,15 +2747,18 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                table_id = rt->rt_table_id;
 
        err = rt_fill_info(net, dst, src, table_id, &fl4, skb,
-                          NETLINK_CB(in_skb).portid, nlh->nlmsg_seq);
+                          NETLINK_CB(in_skb).portid, nlh->nlmsg_seq, rt);
        if (err < 0)
                goto errout_free;
 
+       rcu_read_unlock();
+
        err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
 errout:
        return err;
 
 errout_free:
+       rcu_read_unlock();
        kfree_skb(skb);
        goto errout;
 }