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https://github.com/torvalds/linux
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d1c2b5010d
NUD_STALE is used when the caller(e.g. arp_process()) can't guarantee neighbour reachability. If the entry was NUD_VALID and lladdr is unchanged, the entry state should not be changed. Currently the code puts an extra "NUD_CONNECTED" condition. So if old state was NUD_DELAY or NUD_PROBE (they are NUD_VALID but not NUD_CONNECTED), the state can be changed to NUD_STALE. This may cause problem. Because NUD_STALE lladdr doesn't guarantee reachability, when we send traffic, the state will be changed to NUD_DELAY. In normal case, if we get no confirmation (by dst_confirm()), we will change the state to NUD_PROBE and send probe traffic. But now the state may be reset to NUD_STALE again(e.g. by broadcast ARP packets), so the probe traffic will not be sent. This situation may happen again and again, and packets will be sent to an non-reachable lladdr forever. The fix is to remove the "NUD_CONNECTED" condition. After that the "NEIGH_UPDATE_F_WEAK_OVERRIDE" condition (used by IPv6) in that branch will be redundant, so remove it. This change may increase probe traffic, but it's essential since NUD_STALE lladdr is unreliable. To ensure correctness, we prefer to resolve lladdr, when we can't get confirmation, even while remote packets try to set NUD_STALE state. Signed-off-by: Chunhui He <hchunhui@mail.ustc.edu.cn> Signed-off-by: Julian Anastasov <ja@ssi.bg> Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| .. | ||
| datagram.c | ||
| dev.c | ||
| dev_addr_lists.c | ||
| dev_ioctl.c | ||
| devlink.c | ||
| drop_monitor.c | ||
| dst.c | ||
| dst_cache.c | ||
| ethtool.c | ||
| fib_rules.c | ||
| filter.c | ||
| flow.c | ||
| flow_dissector.c | ||
| gen_estimator.c | ||
| gen_stats.c | ||
| hwbm.c | ||
| link_watch.c | ||
| lwtunnel.c | ||
| Makefile | ||
| neighbour.c | ||
| net-procfs.c | ||
| net-sysfs.c | ||
| net-sysfs.h | ||
| net-traces.c | ||
| net_namespace.c | ||
| netclassid_cgroup.c | ||
| netevent.c | ||
| netpoll.c | ||
| netprio_cgroup.c | ||
| pktgen.c | ||
| ptp_classifier.c | ||
| request_sock.c | ||
| rtnetlink.c | ||
| scm.c | ||
| secure_seq.c | ||
| skbuff.c | ||
| sock.c | ||
| sock_diag.c | ||
| sock_reuseport.c | ||
| stream.c | ||
| sysctl_net_core.c | ||
| timestamping.c | ||
| tso.c | ||
| utils.c | ||