2019-05-23 11:14:38 +02:00
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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2007-12-16 14:06:41 -08:00
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/* SCTP kernel reference Implementation
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* Copyright (c) 1999-2001 Motorola, Inc.
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* Copyright (c) 2001-2003 International Business Machines, Corp.
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*
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* This file is part of the SCTP kernel reference Implementation
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*
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* SCTP Checksum functions
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*
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* Please send any bug reports or fixes you make to the
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* email address(es):
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2013-07-23 14:51:47 +02:00
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* lksctp developers <linux-sctp@vger.kernel.org>
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2007-12-16 14:06:41 -08:00
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*
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* Written or modified by:
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* Dinakaran Joseph
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* Jon Grimm <jgrimm@us.ibm.com>
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* Sridhar Samudrala <sri@us.ibm.com>
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* Vlad Yasevich <vladislav.yasevich@hp.com>
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*/
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2013-07-01 18:10:36 +02:00
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#ifndef __sctp_checksum_h__
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#define __sctp_checksum_h__
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2007-12-16 14:06:41 -08:00
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#include <linux/types.h>
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2022-11-15 10:39:53 -05:00
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#include <linux/sctp.h>
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2019-05-29 17:39:41 +02:00
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2013-07-25 10:52:05 +09:00
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static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
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unsigned int offset)
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{
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2019-03-18 19:47:00 +08:00
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struct sctphdr *sh = (struct sctphdr *)(skb->data + offset);
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2017-11-26 20:16:07 +08:00
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__le32 old = sh->checksum;
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2025-05-19 10:50:07 -07:00
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u32 new;
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2013-07-25 10:52:05 +09:00
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net: sctp: fix and consolidate SCTP checksumming code
This fixes an outstanding bug found through IPVS, where SCTP packets
with skb->data_len > 0 (non-linearized) and empty frag_list, but data
accumulated in frags[] member, are forwarded with incorrect checksum
letting SCTP initial handshake fail on some systems. Linearizing each
SCTP skb in IPVS to prevent that would not be a good solution as
this leads to an additional and unnecessary performance penalty on
the load-balancer itself for no good reason (as we actually only want
to update the checksum, and can do that in a different/better way
presented here).
The actual problem is elsewhere, namely, that SCTP's checksumming
in sctp_compute_cksum() does not take frags[] into account like
skb_checksum() does. So while we are fixing this up, we better reuse
the existing code that we have anyway in __skb_checksum() and use it
for walking through the data doing checksumming. This will not only
fix this issue, but also consolidates some SCTP code with core
sk_buff code, bringing it closer together and removing respectively
avoiding reimplementation of skb_checksum() for no good reason.
As crc32c() can use hardware implementation within the crypto layer,
we leave that intact (it wraps around / falls back to e.g. slice-by-8
algorithm in __crc32c_le() otherwise); plus use the __crc32c_le_combine()
combinator for crc32c blocks.
Also, we remove all other SCTP checksumming code, so that we only
have to use sctp_compute_cksum() from now on; for doing that, we need
to transform SCTP checkumming in output path slightly, and can leave
the rest intact.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-30 11:50:52 +01:00
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sh->checksum = 0;
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2025-05-19 10:50:07 -07:00
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new = ~skb_crc32c(skb, offset, skb->len - offset, ~0);
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net: sctp: fix and consolidate SCTP checksumming code
This fixes an outstanding bug found through IPVS, where SCTP packets
with skb->data_len > 0 (non-linearized) and empty frag_list, but data
accumulated in frags[] member, are forwarded with incorrect checksum
letting SCTP initial handshake fail on some systems. Linearizing each
SCTP skb in IPVS to prevent that would not be a good solution as
this leads to an additional and unnecessary performance penalty on
the load-balancer itself for no good reason (as we actually only want
to update the checksum, and can do that in a different/better way
presented here).
The actual problem is elsewhere, namely, that SCTP's checksumming
in sctp_compute_cksum() does not take frags[] into account like
skb_checksum() does. So while we are fixing this up, we better reuse
the existing code that we have anyway in __skb_checksum() and use it
for walking through the data doing checksumming. This will not only
fix this issue, but also consolidates some SCTP code with core
sk_buff code, bringing it closer together and removing respectively
avoiding reimplementation of skb_checksum() for no good reason.
As crc32c() can use hardware implementation within the crypto layer,
we leave that intact (it wraps around / falls back to e.g. slice-by-8
algorithm in __crc32c_le() otherwise); plus use the __crc32c_le_combine()
combinator for crc32c blocks.
Also, we remove all other SCTP checksumming code, so that we only
have to use sctp_compute_cksum() from now on; for doing that, we need
to transform SCTP checkumming in output path slightly, and can leave
the rest intact.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-30 11:50:52 +01:00
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sh->checksum = old;
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2025-05-19 10:50:07 -07:00
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return cpu_to_le32(new);
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2013-07-25 10:52:05 +09:00
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}
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2013-07-01 18:10:36 +02:00
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#endif /* __sctp_checksum_h__ */
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