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Unlike UDP or TCP, we do not take the pseudo-header into account in SCTP checksums. So in case port mapping is the very same, we do not need to recalculate the whole SCTP checksum in software, which is very expensive. Also, similarly as in TCP, take into account when a private helper mangled the packet. In that case, we also need to recalculate the checksum even if ports might be same. Thanks for feedback regarding skb->ip_summed checks from Julian Anastasov; here's a discussion on these checks for snat and dnat: * For snat_handler(), we can see CHECKSUM_PARTIAL from virtual devices, and from LOCAL_OUT, otherwise it should be CHECKSUM_UNNECESSARY. In general, in snat it is more complex. skb contains the original route and ip_vs_route_me_harder() can change the route after snat_handler. So, for locally generated replies from local server we can not preserve the CHECKSUM_PARTIAL mode. It is an chicken or egg dilemma: snat_handler needs the device after rerouting (to check for NETIF_F_SCTP_CSUM), while ip_route_me_harder() wants the snat_handler() to put the new saddr for proper rerouting. * For dnat_handler(), we should not see CHECKSUM_COMPLETE for SCTP, in fact the small set of drivers that support SCTP offloading return CHECKSUM_UNNECESSARY on correctly received SCTP csum. We can see CHECKSUM_PARTIAL from local stack or received from virtual drivers. The idea is that SCTP decides to avoid csum calculation if hardware supports offloading. IPVS can change the device after rerouting to real server but we can preserve the CHECKSUM_PARTIAL mode if the new device supports offloading too. This works because skb dst is changed before dnat_handler and we see the new device. So, checks in the 'if' part will decide whether it is ok to keep CHECKSUM_PARTIAL for the output. If the packet was with CHECKSUM_NONE, hence we deal with unknown checksum. As we recalculate the sum for IP header in all cases, it should be safe to use CHECKSUM_UNNECESSARY. We can forward wrong checksum in this case (without cp->app). In case of CHECKSUM_UNNECESSARY, the csum was valid on receive. Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au> |
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| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bridge | ||
| caif | ||
| can | ||
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| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
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| ipv4 | ||
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| ipx | ||
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| iucv | ||
| key | ||
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| mac80211 | ||
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| mpls | ||
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| packet | ||
| phonet | ||
| rds | ||
| rfkill | ||
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| sched | ||
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| sunrpc | ||
| tipc | ||
| unix | ||
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| wireless | ||
| x25 | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| nonet.c | ||
| socket.c | ||
| sysctl_net.c | ||