Hi Davide,
I suggest this patch subject:
nf_tables: nft_inner: validate mandatory meta and payload netlink attributes
On Tue, Jun 04, 2024 at 11:36:21PM +0200, Davide Ornaghi wrote:
> Payload and meta nftables exprs can be embedded into inner exprs via
> nft_expr_inner_parse, which doesn't check for NULL netlink attributes,
> unlike other exprs passing through select_ops.
> Add the missing checks to nft_meta_inner_init and nft_payload_inner_init
> to prevent dereferencing NULL pointers and eventually causing UAF reads on commit_mutex.
I'd suggest this patch description:
"Check for mandatory netlink attributes in payload and meta expression
when used embedded from the inner expression, otherwise NULL pointer
dereference is possible if userspace."
And please add:
Fixes: a150d122b6bd ("netfilter: nft_meta: add inner match support")
Fixes: 3a07327d10a0 ("netfilter: nft_inner: support for inner tunnel header matching")
Thanks a lot for submitting your fix.
> Signed-off-by: Davide Ornaghi <d.ornaghi97@xxxxxxxxx>
> ---
> net/netfilter/nft_meta.c | 2 ++
> net/netfilter/nft_payload.c | 3 +++
> 2 files changed, 5 insertions(+)
>
> diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
> index ba0d3683a..e2893077b 100644
> --- a/net/netfilter/nft_meta.c
> +++ b/net/netfilter/nft_meta.c
> @@ -839,6 +839,8 @@ static int nft_meta_inner_init(const struct nft_ctx
> *ctx,
> struct nft_meta *priv = nft_expr_priv(expr);
> unsigned int len;
>
> + if (!tb[NFTA_META_KEY] || !tb[NFTA_META_DREG])
> + return -EINVAL;
> priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));
> switch (priv->key) {
> case NFT_META_PROTOCOL:
> diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
> index 0c43d748e..4c6f15ad0 100644
> --- a/net/netfilter/nft_payload.c
> +++ b/net/netfilter/nft_payload.c
> @@ -650,6 +650,9 @@ static int nft_payload_inner_init(const struct nft_ctx
> *ctx,
> struct nft_payload *priv = nft_expr_priv(expr);
> u32 base;
>
> + if (!tb[NFTA_PAYLOAD_BASE] || !tb[NFTA_PAYLOAD_OFFSET] ||
> + !tb[NFTA_PAYLOAD_LEN] || !tb[NFTA_PAYLOAD_DREG])
> + return -EINVAL;
> base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
> switch (base) {
> case NFT_PAYLOAD_TUN_HEADER:
> --
> 2.34.1
