e6d8b64b34
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>
79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
/* 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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* The SCTP reference implementation is free software;
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* you can redistribute it and/or modify it under the terms of
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* the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* The SCTP reference implementation is distributed in the hope that it
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* will be useful, but WITHOUT ANY WARRANTY; without even the implied
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* ************************
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU CC; see the file COPYING. If not, write to
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* the Free Software Foundation, 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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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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* lksctp developers <linux-sctp@vger.kernel.org>
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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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*
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* Rewritten to use libcrc32c by:
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* Vlad Yasevich <vladislav.yasevich@hp.com>
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*/
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#ifndef __sctp_checksum_h__
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#define __sctp_checksum_h__
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#include <linux/types.h>
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#include <net/sctp/sctp.h>
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#include <linux/crc32c.h>
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#include <linux/crc32.h>
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static inline __wsum sctp_csum_update(const void *buff, int len, __wsum sum)
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{
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/* This uses the crypto implementation of crc32c, which is either
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* implemented w/ hardware support or resolves to __crc32c_le().
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*/
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return crc32c(sum, buff, len);
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}
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static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
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int offset, int len)
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{
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return __crc32c_le_combine(csum, csum2, len);
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}
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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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struct sctphdr *sh = sctp_hdr(skb);
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__le32 ret, old = sh->checksum;
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const struct skb_checksum_ops ops = {
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.update = sctp_csum_update,
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.combine = sctp_csum_combine,
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};
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sh->checksum = 0;
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ret = cpu_to_le32(~__skb_checksum(skb, offset, skb->len - offset,
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~(__u32)0, &ops));
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sh->checksum = old;
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return ret;
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}
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#endif /* __sctp_checksum_h__ */
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