sched: cls_flow: use skb_to_full_sk() helper

SYNACK packets might be attached to request sockets.

Fixes: ca6fb065 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flow.c

@@ -22,6 +22,7 @@
 #include <linux/if_vlan.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <net/inet_sock.h>
 
 #include <net/pkt_cls.h>
 #include <net/ip.h>
@@ -197,8 +198,11 @@ static u32 flow_get_rtclassid(const struct sk_buff *skb)
 
 static u32 flow_get_skuid(const struct sk_buff *skb)
 {
-	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file) {
-		kuid_t skuid = skb->sk->sk_socket->file->f_cred->fsuid;
+	struct sock *sk = skb_to_full_sk(skb);
+
+	if (sk && sk->sk_socket && sk->sk_socket->file) {
+		kuid_t skuid = sk->sk_socket->file->f_cred->fsuid;
+
 		return from_kuid(&init_user_ns, skuid);
 	}
 	return 0;
@@ -206,8 +210,11 @@ static u32 flow_get_skuid(const struct sk_buff *skb)
 
 static u32 flow_get_skgid(const struct sk_buff *skb)
 {
-	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file) {
-		kgid_t skgid = skb->sk->sk_socket->file->f_cred->fsgid;
+	struct sock *sk = skb_to_full_sk(skb);
+
+	if (sk && sk->sk_socket && sk->sk_socket->file) {
+		kgid_t skgid = sk->sk_socket->file->f_cred->fsgid;
+
 		return from_kgid(&init_user_ns, skgid);
 	}
 	return 0;