netfilter: conntrack: validate SCTP crc32c in PREROUTING

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implement sctp_error to let nf_conntrack_in validate crc32c on the packet
transport header. Assign skb->ip_summed to CHECKSUM_UNNECESSARY and return
NF_ACCEPT in case of successful validation; otherwise, return -NF_ACCEPT to
let netfilter skip connection tracking, like other protocols do.

Besides preventing corrupted packets from matching conntrack entries, this
fixes functionality of REJECT target: it was not generating any ICMP upon
reception of SCTP packets, because it was computing RFC 1624 checksum on
the packet and systematically mismatching crc32c in the SCTP header.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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Davide Caratti 2017-01-02 13:29:41 +01:00 • committed by Pablo Neira Ayuso

parent 300ae14946

commit cf6e007eef

1 changed files with 32 additions and 0 deletions

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net/netfilter/nf_conntrack_proto_sctp.c

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