From f342de4e2f33e0e39165d8639387aa6c19dff660 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sat, 20 Jan 2024 22:50:04 +0100 Subject: [PATCH] netfilter: nf_tables: reject QUEUE/DROP verdict parameters 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 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 02f45424644b..c537104411e7 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -10992,16 +10992,10 @@ 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: @@ -11036,6 +11030,8 @@ 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); -- 2.34.1