Patch "netfilter: nft_limit: do not ignore unsupported flags" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    netfilter: nft_limit: do not ignore unsupported flags

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-nft_limit-do-not-ignore-unsupported-flags.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d5905d79aae4d2913c8106508718b659a1c0cafb
Author: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Date:   Wed Jan 10 00:42:37 2024 +0100

    netfilter: nft_limit: do not ignore unsupported flags
    
    [ Upstream commit 91a139cee1202a4599a380810d93c69b5bac6197 ]
    
    Bail out if userspace provides unsupported flags, otherwise future
    extensions to the limit expression will be silently ignored by the
    kernel.
    
    Fixes: c7862a5f0de5 ("netfilter: nft_limit: allow to invert matching criteria")
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/netfilter/nft_limit.c b/net/netfilter/nft_limit.c
index 981addb2d051..75c05ef885a9 100644
--- a/net/netfilter/nft_limit.c
+++ b/net/netfilter/nft_limit.c
@@ -58,6 +58,7 @@ static inline bool nft_limit_eval(struct nft_limit_priv *priv, u64 cost)
 static int nft_limit_init(struct nft_limit_priv *priv,
 			  const struct nlattr * const tb[], bool pkts)
 {
+	bool invert = false;
 	u64 unit, tokens;
 
 	if (tb[NFTA_LIMIT_RATE] == NULL ||
@@ -90,19 +91,23 @@ static int nft_limit_init(struct nft_limit_priv *priv,
 				 priv->rate);
 	}
 
+	if (tb[NFTA_LIMIT_FLAGS]) {
+		u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));
+
+		if (flags & ~NFT_LIMIT_F_INV)
+			return -EOPNOTSUPP;
+
+		if (flags & NFT_LIMIT_F_INV)
+			invert = true;
+	}
+
 	priv->limit = kmalloc(sizeof(*priv->limit), GFP_KERNEL_ACCOUNT);
 	if (!priv->limit)
 		return -ENOMEM;
 
 	priv->limit->tokens = tokens;
 	priv->tokens_max = priv->limit->tokens;
-
-	if (tb[NFTA_LIMIT_FLAGS]) {
-		u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));
-
-		if (flags & NFT_LIMIT_F_INV)
-			priv->invert = true;
-	}
+	priv->invert = invert;
 	priv->limit->last = ktime_get_ns();
 	spin_lock_init(&priv->limit->lock);