[PATCH nf-next] netfilter: nf_tables: call skb_valid_dst() before skb_dst()

When fetching the dst_entry from the skb, check if it valid, ie. this is
not a template dst.

Signed-off-by: Pablo Neira Ayuso <[email protected]>
---
 net/netfilter/nft_meta.c | 6 ++++--
 net/netfilter/nft_rt.c   | 6 ++++--
 net/netfilter/nft_xfrm.c | 9 ++++++++-
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 0a43e0787a68..01cfbaa36525 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -20,6 +20,7 @@
 #include <net/dst.h>
 #include <net/ip.h>
 #include <net/sock.h>
+#include <net/dst_metadata.h>
 #include <net/tcp_states.h> /* for TCP_TIME_WAIT */
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables_core.h>
@@ -279,11 +280,12 @@ static bool nft_meta_get_eval_ifname(enum nft_meta_keys key, u32 *dest,
 static noinline bool
 nft_meta_get_eval_rtclassid(const struct sk_buff *skb, u32 *dest)
 {
-	const struct dst_entry *dst = skb_dst(skb);
+	const struct dst_entry *dst;
 
-	if (!dst)
+	if (!skb_valid_dst(skb))
 		return false;
 
+	dst = skb_dst(skb);
 	*dest = dst->tclassid;
 	return true;
 }
diff --git a/net/netfilter/nft_rt.c b/net/netfilter/nft_rt.c
index aeb0094eafd8..841c863a08db 100644
--- a/net/netfilter/nft_rt.c
+++ b/net/netfilter/nft_rt.c
@@ -8,6 +8,7 @@
 #include <linux/netfilter.h>
 #include <linux/netfilter/nf_tables.h>
 #include <net/dst.h>
+#include <net/dst_metadata.h>
 #include <net/ip6_route.h>
 #include <net/route.h>
 #include <net/netfilter/nf_tables.h>
@@ -59,10 +60,11 @@ void nft_rt_get_eval(const struct nft_expr *expr,
 	u32 *dest = &regs->data[priv->dreg];
 	const struct dst_entry *dst;
 
-	dst = skb_dst(skb);
-	if (!dst)
+	if (!skb_valid_dst(skb))
 		goto err;
 
+	dst = skb_dst(skb);
+
 	switch (priv->key) {
 #ifdef CONFIG_IP_ROUTE_CLASSID
 	case NFT_RT_CLASSID:
diff --git a/net/netfilter/nft_xfrm.c b/net/netfilter/nft_xfrm.c
index 8cec43064319..c8bba697f993 100644
--- a/net/netfilter/nft_xfrm.c
+++ b/net/netfilter/nft_xfrm.c
@@ -12,6 +12,7 @@
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables_core.h>
 #include <net/netfilter/nf_tables.h>
+#include <net/dst_metadata.h>
 #include <linux/in.h>
 #include <net/xfrm.h>
 
@@ -177,9 +178,15 @@ static void nft_xfrm_get_eval_out(const struct nft_xfrm *priv,
 				  struct nft_regs *regs,
 				  const struct nft_pktinfo *pkt)
 {
-	const struct dst_entry *dst = skb_dst(pkt->skb);
+	const struct dst_entry *dst;
 	int i;
 
+	if (!skb_valid_dst(pkt->skb)) {
+		regs->verdict.code = NFT_BREAK;
+		return;
+	}
+
+	dst = skb_dst(pkt->skb);
 	for (i = 0; dst && dst->xfrm;
 	     dst = ((const struct xfrm_dst *)dst)->child, i++) {
 		if (i < priv->spnum)
-- 
2.47.3