ipv4: Convert ip_route_input_rcu() to dscp_t.

Pass a dscp_t variable to ip_route_input_rcu(), instead of a plain u8,
to prevent accidental setting of ECN bits in ->flowi4_tos.

Callers of ip_route_input_rcu() to consider are:

  * ip_route_input_noref(), which already has a dscp_t variable to pass
    as parameter. We just need to remove the inet_dscp_to_dsfield()
    conversion.

  * inet_rtm_getroute(), which receives a u8 from user space and needs
    to convert it with inet_dsfield_to_dscp().

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/c4dbb5aa9cbc79c4fcb317abbffa7c7156bc56a7.1727807926.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 00bfc0a11f64c6d9e2de39e79ab5de635c4030cd..a693b57b41118f1601de5d46a321bf879e1e0030 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2415,7 +2415,8 @@ martian_source:
 
 /* called with rcu_read_lock held */
 static int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-                             u8 tos, struct net_device *dev, struct fib_result *res)
+                             dscp_t dscp, struct net_device *dev,
+                             struct fib_result *res)
 {
        /* Multicast recognition logic is moved from route cache to here.
         * The problem was that too many Ethernet cards have broken/missing
@@ -2456,12 +2457,14 @@ static int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 #endif
                   ) {
                        err = ip_route_input_mc(skb, daddr, saddr,
-                                               tos, dev, our);
+                                               inet_dscp_to_dsfield(dscp),
+                                               dev, our);
                }
                return err;
        }
 
-       return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
+       return ip_route_input_slow(skb, daddr, saddr,
+                                  inet_dscp_to_dsfield(dscp), dev, res);
 }
 
 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
@@ -2471,8 +2474,7 @@ int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
        int err;
 
        rcu_read_lock();
-       err = ip_route_input_rcu(skb, daddr, saddr, inet_dscp_to_dsfield(dscp),
-                                dev, &res);
+       err = ip_route_input_rcu(skb, daddr, saddr, dscp, dev, &res);
        rcu_read_unlock();
 
        return err;
@@ -3286,8 +3288,8 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                skb->dev        = dev;
                skb->mark       = mark;
                err = ip_route_input_rcu(skb, dst, src,
-                                        rtm->rtm_tos & INET_DSCP_MASK, dev,
-                                        &res);
+                                        inet_dsfield_to_dscp(rtm->rtm_tos),
+                                        dev, &res);
 
                rt = skb_rtable(skb);
                if (err == 0 && rt->dst.error)