diff mbox series

[SRU,Mantic,Jammy,1/1] netfilter: nf_tables: reject QUEUE/DROP verdict parameters

Message ID 20240209211125.56995-2-bethany.jamison@canonical.com
State New
Headers show
Series [SRU,Mantic,Jammy,1/1] netfilter: nf_tables: reject QUEUE/DROP verdict parameters | expand

Commit Message

Bethany Jamison Feb. 9, 2024, 9:11 p.m. UTC 
From: Florian Westphal <fw@strlen.de>

This reverts commit e0abdadcc6e1.

core.c:nf_hook_slow assumes that the upper 16 bits of NF_DROP
verdicts contain a valid errno, i.e. -EPERM, -EHOSTUNREACH or similar,
or 0.

Due to the reverted commit, its possible to provide a positive
value, e.g. NF_ACCEPT (1), which results in use-after-free.

Its not clear to me why this commit was made.

NF_QUEUE is not used by nftables; "queue" rules in nftables
will result in use of "nft_queue" expression.

If we later need to allow specifiying errno values from userspace
(do not know why), this has to call NF_DROP_GETERR and check that
"err <= 0" holds true.

Fixes: e0abdadcc6e1 ("netfilter: nf_tables: accept QUEUE/DROP verdict parameters")
Cc: stable@vger.kernel.org
Reported-by: Notselwyn <notselwyn@pwning.tech>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit f342de4e2f33e0e39165d8639387aa6c19dff660)
CVE-2024-1086
Signed-off-by: Bethany Jamison <bethany.jamison@canonical.com>
---
 net/netfilter/nf_tables_api.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 2410695975ae8..6b9eea5cc58d4 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10835,16 +10835,10 @@  static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 	data->verdict.code = ntohl(nla_get_be32(tb[NFTA_VERDICT_CODE]));
 
 	switch (data->verdict.code) {
-	default:
-		switch (data->verdict.code & NF_VERDICT_MASK) {
-		case NF_ACCEPT:
-		case NF_DROP:
-		case NF_QUEUE:
-			break;
-		default:
-			return -EINVAL;
-		}
-		fallthrough;
+	case NF_ACCEPT:
+	case NF_DROP:
+	case NF_QUEUE:
+		break;
 	case NFT_CONTINUE:
 	case NFT_BREAK:
 	case NFT_RETURN:
@@ -10879,6 +10873,8 @@  static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
 
 		data->verdict.chain = chain;
 		break;
+	default:
+		return -EINVAL;
 	}
 
 	desc->len = sizeof(data->verdict);