Messages in this thread | | | Subject | Re: [net-next PATCH v4 3/3] net: reserve ports for applications using fixed port numbers | From | Eric Dumazet <> | Date | Tue, 16 Feb 2010 14:20:25 +0100 |
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Le mardi 16 février 2010 à 21:06 +0800, Cong Wang a écrit : > Octavian Purdila wrote: > > On Tuesday 16 February 2010 11:37:04 you wrote: > >>> BUILD_BUG_ON(sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb)); > >>> > >>> + sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL); > >>> + if (!sysctl_local_reserved_ports) > >>> + goto out; > >>> + > >> I think we should also consider the ports in ip_local_port_range, > >> since we can only reserve the ports in that range. > >> > > > > That is subject to changes at runtime, which means we will have to readjust > > the bitmap at runtime which introduces the need for additional synchronization > > operations which I would rather avoid. > > Why? As long as the bitmap is global, this will not be hard. > > Consider that if one user writes a port number which is beyond > the ip_local_port_range into ip_local_reserved_ports, we should > not accept this, because it doesn't make any sense. But with your > patch, we do.
I disagree with you. This is perfectly OK.
A port not being flagged in ip_local_reserved_ports doesnt mean it can be used for allocation.
If you want to really block ports from being used at boot, you could for example :
# temporarly reduce the ip_local_port_range echo "61000 61001" >/proc/sys/net/ipv4/ip_local_port_range # Build our bitmap (could be slow, if a remote database is read) for port in $LIST_RESERVED_PORT do echo $port >/proc/sys/net/ipv4/ip_local_reserved_ports done echo "10000 61000" >/proc/sys/net/ipv4/ip_local_port_range
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