netdev - [PATCH net-next 2/7] netfilter: nf_tables: mask out non-verdict bits when checking return value

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Message-ID: <20231018085118.10829-3-fw@strlen.de>
Date: Wed, 18 Oct 2023 10:51:06 +0200
From: Florian Westphal <fw@...len.de>
To: <netdev@...r.kernel.org>
Cc: Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	<netfilter-devel@...r.kernel.org>
Subject: [PATCH net-next 2/7] netfilter: nf_tables: mask out non-verdict bits when checking return value

nftables trace infra must mask out the non-verdict bit parts of the
return value, else followup changes that 'return errno << 8 | NF_STOLEN'
will cause breakage.

Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nf_tables_core.c  | 2 +-
 net/netfilter/nf_tables_trace.c | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 4d0ce12221f6..6009b423f60a 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -115,7 +115,7 @@ static noinline void __nft_trace_verdict(const struct nft_pktinfo *pkt,
 {
 	enum nft_trace_types type;
 
-	switch (regs->verdict.code) {
+	switch (regs->verdict.code & NF_VERDICT_MASK) {
 	case NFT_CONTINUE:
 	case NFT_RETURN:
 		type = NFT_TRACETYPE_RETURN;
diff --git a/net/netfilter/nf_tables_trace.c b/net/netfilter/nf_tables_trace.c
index 6d41c0bd3d78..a83637e3f455 100644
--- a/net/netfilter/nf_tables_trace.c
+++ b/net/netfilter/nf_tables_trace.c
@@ -258,17 +258,21 @@ void nft_trace_notify(const struct nft_pktinfo *pkt,
 	case __NFT_TRACETYPE_MAX:
 		break;
 	case NFT_TRACETYPE_RETURN:
-	case NFT_TRACETYPE_RULE:
+	case NFT_TRACETYPE_RULE: {
+		unsigned int v;
+
 		if (nft_verdict_dump(skb, NFTA_TRACE_VERDICT, verdict))
 			goto nla_put_failure;
 
 		/* pkt->skb undefined iff NF_STOLEN, disable dump */
-		if (verdict->code == NF_STOLEN)
+		v = verdict->code & NF_VERDICT_MASK;
+		if (v == NF_STOLEN)
 			info->packet_dumped = true;
 		else
 			mark = pkt->skb->mark;
 
 		break;
+	}
 	case NFT_TRACETYPE_POLICY:
 		mark = pkt->skb->mark;
 
-- 
2.41.0