netdev - [PATCH net-next 2/2] netfilter: nft_payload: reject out-of-range attributes via policy

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Date:   Mon,  5 Sep 2022 12:09:37 +0200
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     netfilter-devel@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Florian Westphal <fw@...len.de>
Subject: [PATCH net-next 2/2] netfilter: nft_payload: reject out-of-range attributes via policy

Now that nla_policy allows range checks for bigendian data make use of
this to reject such attributes.  At this time, reject happens later
from the init or select_ops callbacks, but its prone to errors.

In the future, new attributes can be handled via NLA_POLICY_MAX_BE
and exiting ones can be converted one by one.

Signed-off-by: Florian Westphal <fw@...len.de>
---
 net/netfilter/nft_payload.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index eb0e40c29712..088244f9d838 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -173,10 +173,10 @@ static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
 	[NFTA_PAYLOAD_SREG]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_DREG]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_BASE]		= { .type = NLA_U32 },
-	[NFTA_PAYLOAD_OFFSET]		= { .type = NLA_U32 },
-	[NFTA_PAYLOAD_LEN]		= { .type = NLA_U32 },
+	[NFTA_PAYLOAD_OFFSET]		= NLA_POLICY_MAX_BE(NLA_U32, 255),
+	[NFTA_PAYLOAD_LEN]		= NLA_POLICY_MAX_BE(NLA_U32, 255),
 	[NFTA_PAYLOAD_CSUM_TYPE]	= { .type = NLA_U32 },
-	[NFTA_PAYLOAD_CSUM_OFFSET]	= { .type = NLA_U32 },
+	[NFTA_PAYLOAD_CSUM_OFFSET]	= NLA_POLICY_MAX_BE(NLA_U32, 255),
 	[NFTA_PAYLOAD_CSUM_FLAGS]	= { .type = NLA_U32 },
 };
 
-- 
2.35.1