netdev - [PATCH net 3/3] netfilter: nft_queue: only allow supported familes and hooks

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Date:   Tue, 26 Jul 2022 21:20:56 +0200
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     Paolo Abeni <pabeni@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH net 3/3] netfilter: nft_queue: only allow supported familes and hooks

Trying to use 'queue' statement in ingress (for example)
triggers a splat on reinject:

WARNING: CPU: 3 PID: 1345 at net/netfilter/nf_queue.c:291

... because nf_reinject cannot find the ruleset head.

The netdev family doesn't support async resume at the moment anyway,
so disallow loading such rulesets with a more appropriate
error message.

v2: add 'validate' callback and also check hook points, v1 did
allow ingress use in 'table inet', but that doesn't work either. (Pablo)

Signed-off-by: Florian Westphal <fw@...len.de>
Reviewed-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nft_queue.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/net/netfilter/nft_queue.c b/net/netfilter/nft_queue.c
index 15e4b7640dc0..da29e92c03e2 100644
--- a/net/netfilter/nft_queue.c
+++ b/net/netfilter/nft_queue.c
@@ -68,6 +68,31 @@ static void nft_queue_sreg_eval(const struct nft_expr *expr,
 	regs->verdict.code = ret;
 }
 
+static int nft_queue_validate(const struct nft_ctx *ctx,
+			      const struct nft_expr *expr,
+			      const struct nft_data **data)
+{
+	static const unsigned int supported_hooks = ((1 << NF_INET_PRE_ROUTING) |
+						     (1 << NF_INET_LOCAL_IN) |
+						     (1 << NF_INET_FORWARD) |
+						     (1 << NF_INET_LOCAL_OUT) |
+						     (1 << NF_INET_POST_ROUTING));
+
+	switch (ctx->family) {
+	case NFPROTO_IPV4:
+	case NFPROTO_IPV6:
+	case NFPROTO_INET:
+	case NFPROTO_BRIDGE:
+		break;
+	case NFPROTO_NETDEV: /* lacks okfn */
+		fallthrough;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return nft_chain_validate_hooks(ctx->chain, supported_hooks);
+}
+
 static const struct nla_policy nft_queue_policy[NFTA_QUEUE_MAX + 1] = {
 	[NFTA_QUEUE_NUM]	= { .type = NLA_U16 },
 	[NFTA_QUEUE_TOTAL]	= { .type = NLA_U16 },
@@ -164,6 +189,7 @@ static const struct nft_expr_ops nft_queue_ops = {
 	.eval		= nft_queue_eval,
 	.init		= nft_queue_init,
 	.dump		= nft_queue_dump,
+	.validate	= nft_queue_validate,
 	.reduce		= NFT_REDUCE_READONLY,
 };
 
@@ -173,6 +199,7 @@ static const struct nft_expr_ops nft_queue_sreg_ops = {
 	.eval		= nft_queue_sreg_eval,
 	.init		= nft_queue_sreg_init,
 	.dump		= nft_queue_sreg_dump,
+	.validate	= nft_queue_validate,
 	.reduce		= NFT_REDUCE_READONLY,
 };
 
-- 
2.35.1