netfilter: nft_socket: only do sk lookups when indev is available

Check if the incoming interface is available and NFT_BREAK
in case neither skb->sk nor input device are set.

Because nf_sk_lookup_slow*() assume packet headers are in the
'in' direction, use in postrouting is not going to yield a meaningful
result.  Same is true for the forward chain, so restrict the use
to prerouting, input and output.

Use in output work if a socket is already attached to the skb.

Fixes: 554ced0a6e29 ("netfilter: nf_tables: add support for native socket matching")
Reported-and-tested-by: Topi Miettinen <toiwoton@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c
index 6d9e8e0..05ae5a3 100644 (file)
--- a/net/netfilter/nft_socket.c
+++ b/net/netfilter/nft_socket.c
@@ -54,6 +54,32 @@ nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo
 }
 #endif
 
+static struct sock *nft_socket_do_lookup(const struct nft_pktinfo *pkt)
+{
+       const struct net_device *indev = nft_in(pkt);
+       const struct sk_buff *skb = pkt->skb;
+       struct sock *sk = NULL;
+
+       if (!indev)
+               return NULL;
+
+       switch (nft_pf(pkt)) {
+       case NFPROTO_IPV4:
+               sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, indev);
+               break;
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+       case NFPROTO_IPV6:
+               sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, indev);
+               break;
+#endif
+       default:
+               WARN_ON_ONCE(1);
+               break;
+       }
+
+       return sk;
+}
+
 static void nft_socket_eval(const struct nft_expr *expr,
                            struct nft_regs *regs,
                            const struct nft_pktinfo *pkt)
@@ -67,20 +93,7 @@ static void nft_socket_eval(const struct nft_expr *expr,
                sk = NULL;
 
        if (!sk)
-               switch(nft_pf(pkt)) {
-               case NFPROTO_IPV4:
-                       sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt));
-                       break;
-#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
-               case NFPROTO_IPV6:
-                       sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt));
-                       break;
-#endif
-               default:
-                       WARN_ON_ONCE(1);
-                       regs->verdict.code = NFT_BREAK;
-                       return;
-               }
+               sk = nft_socket_do_lookup(pkt);
 
        if (!sk) {
                regs->verdict.code = NFT_BREAK;
@@ -224,6 +237,16 @@ static bool nft_socket_reduce(struct nft_regs_track *track,
        return nft_expr_reduce_bitwise(track, expr);
 }
 
+static int nft_socket_validate(const struct nft_ctx *ctx,
+                              const struct nft_expr *expr,
+                              const struct nft_data **data)
+{
+       return nft_chain_validate_hooks(ctx->chain,
+                                       (1 << NF_INET_PRE_ROUTING) |
+                                       (1 << NF_INET_LOCAL_IN) |
+                                       (1 << NF_INET_LOCAL_OUT));
+}
+
 static struct nft_expr_type nft_socket_type;
 static const struct nft_expr_ops nft_socket_ops = {
        .type           = &nft_socket_type,
@@ -231,6 +254,7 @@ static const struct nft_expr_ops nft_socket_ops = {
        .eval           = nft_socket_eval,
        .init           = nft_socket_init,
        .dump           = nft_socket_dump,
+       .validate       = nft_socket_validate,
        .reduce         = nft_socket_reduce,
 };