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netfilter: nft_exthdr: Search chunks in SCTP packets only

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[ Upstream commit 5acc44f39458f43dac9724cefa4da29847cfe997 ]

Since user space does not generate a payload dependency, plain sctp
chunk matches cause searching in non-SCTP packets, too. Avoid this
potential mis-interpretation of packet data by checking pkt->tprot.

Fixes: 133dc203d77df ("netfilter: nft_exthdr: Support SCTP chunks")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Phil Sutter
2021-06-11 19:06:45 +02:00
committed by Greg Kroah-Hartman
parent 152b8ac839
commit e18216cd0e
1 changed files with 4 additions and 1 deletions
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5
net/netfilter/nft_exthdr.c
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@@ -371,6 +371,9 @@ static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
const struct sctp_chunkhdr *sch; const struct sctp_chunkhdr *sch;
struct sctp_chunkhdr _sch; struct sctp_chunkhdr _sch;
if (pkt->tprot != IPPROTO_SCTP)
goto err;
do { do {
sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch); sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch);
if (!sch || !sch->length) if (!sch || !sch->length)
@@ -391,7 +394,7 @@ static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
} }
offset += SCTP_PAD4(ntohs(sch->length)); offset += SCTP_PAD4(ntohs(sch->length));
} while (offset < pkt->skb->len); } while (offset < pkt->skb->len);
err:
if (priv->flags & NFT_EXTHDR_F_PRESENT) if (priv->flags & NFT_EXTHDR_F_PRESENT)
nft_reg_store8(dest, false); nft_reg_store8(dest, false);
else else