[PATCH net 08/10] netfilter: bpf: reject invalid NAT manipulation types

[Pablo Neira Ayuso <pablo@netfilter.org>]

From: Fernando Fernandez Mancera <fmancera@suse.de>

As bpf_ct_set_nat_info() is not validating the NAT manipulation type a
wrong value can be passed directly to nf_nat_setup_info(). This triggers
the WARN_ON() at nf_nat_setup_info() and if panic_on_warn isn't set,
then IPS_SRC_NAT_DONE is set without adding nat_bysource and conntrack
cleanup tries to unlink an uninitialized hlist node.

Fix this by checking that NAT manipulation type is correct before
calling nf_nat_setup_info(). In addition, if the WARN_ON is hit, return
NF_DROP instead of continuing with the processing to avoid similar
situations in the future.

Reported-by: VEGA <vega@nebusec.ai>
Fixes: 0fabd2aa199f ("net: netfilter: add bpf_ct_set_nat_info kfunc helper")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_nat_bpf.c  | 3 +++
 net/netfilter/nf_nat_core.c | 5 +++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_nat_bpf.c b/net/netfilter/nf_nat_bpf.c
index f9dd85ccea01..7572b58c448b 100644
--- a/net/netfilter/nf_nat_bpf.c
+++ b/net/netfilter/nf_nat_bpf.c
@@ -39,6 +39,9 @@ __bpf_kfunc int bpf_ct_set_nat_info(struct nf_conn___init *nfct,
 	if (proto != NFPROTO_IPV4 && proto != NFPROTO_IPV6)
 		return -EINVAL;
 
+	if (manip != NF_NAT_MANIP_SRC && manip != NF_NAT_MANIP_DST)
+		return -EINVAL;
+
 	memset(&range, 0, sizeof(struct nf_nat_range2));
 	range.flags = NF_NAT_RANGE_MAP_IPS;
 	range.min_addr = *addr;
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index a4858c2b2d65..cc8e1e81006d 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -767,8 +767,9 @@ nf_nat_setup_info(struct nf_conn *ct,
 	if (nf_ct_is_confirmed(ct))
 		return NF_ACCEPT;
 
-	WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
-		maniptype != NF_NAT_MANIP_DST);
+	if (WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
+		    maniptype != NF_NAT_MANIP_DST))
+		return NF_DROP;
 
 	if (WARN_ON(nf_nat_initialized(ct, maniptype)))
 		return NF_DROP;
-- 
2.47.3