When dnsmasq forks a child to handle a TCP connection, that
child inherits the netlink socket that the main process has open.
The child never uses that socket, but there's a chance that when the
main process uses the netlink socket, the answer will go to a child
process which has a copy of the socket. This causes the main process
to block forever awaiting the answer which never comes.
The solution is for the child process to close the netlink socket it
inherits after the fork(). There's a nasty race because the error
decribed above could still occur in the window between the fork()
and the close() syscalls. That's fixed by blocking the parent awaiting
a single byte sent though the pipe the two processes share. This byte
is sent by the child after calling close() on the netlink socket.
Thanks to Alin Năstac for spotting this.
When a request matching the clid or mac address is
recieved the server will iterate over all candidate
addresses until it find's one that is not already
leased to a different clid/iaid and advertise
this address.
Using multiple reservations for a single host makes it
possible to maintain a static leases only configuration
which support network booting systems with UEFI firmware
that request a new address (a new SOLICIT with a new IA_NA
option using a new IAID) for different boot modes, for
instance 'PXE over IPv6', and 'HTTP-Boot over IPv6'. Open
Virtual Machine Firmware (OVMF) and most UEFI firmware
build on the EDK2 code base exhibit this behaviour.
The previous code here, which started fast-RA whenever that local
address associated with a DHCP context changed, is very vulnerable
to flapping due to dynamically created addresses in the same net.
Simplify so that if a context which has never found an interface now
finds one, that gets advertised, but not for other changes. That satisfies
the original intention that prefixes not in place when dnsmasq starts
should be recognised.
Also totally ignore all interfaces where we are configured not to do DHCP,
to preclude flapping of they have prefixes in common with interfaces
where we do DHCP.
Fail on overlarge files (block numbers are limited to 16 bits)
Honour tftp-max setting in single port mode.
Tweak timeouts, and fix logic which suppresses errors if the
last ACK is missing.
Hello,
My home network has a DNS search domain of home.arpa and my machine's dnsmasq
instance is configured with:
server=/home.arpa/192.168.0.1
server=//192.168.0.1
stop-dns-rebind
rebind-domain-ok=home.arpa
rebind-domain-ok=// # Match unqualified domains
Querying my router's FQDN works as expected:
dnsmasq: query[A] gateway.home.arpa from 127.0.0.1
dnsmasq: forwarded gateway.home.arpa to 192.168.0.1
dnsmasq: reply gateway.home.arpa is 192.168.0.1
But using an unqualified domain name does not:
dnsmasq: query[A] gateway from 127.0.0.1
dnsmasq: forwarded gateway to 192.168.0.1
dnsmasq: possible DNS-rebind attack detected: gateway
The attached patch addresses this issue by checking for SERV_NO_REBIND when
handling dotless domains.
>From 0460b07108b009cff06e29eac54910ec2e7fafce Mon Sep 17 00:00:00 2001
From: guns <self@sungpae.com>
Date: Mon, 30 Dec 2019 16:34:23 -0600
Subject: [PATCH] Check for SERV_NO_REBIND on unqualified domains
Calling lease_update_file() _can_ result in a call to periodic_ra()
Since both the DHCPv6 and RA subsystems use the same packet buffer
this can overwrite the DHCPv6 packet. To avoid this we ensure the
DHCPv6 packet has been sent before calling lease_update_file().
Order dnsmasq.service before network.target and after network-online.target & nss-lookup.target. Additionally pull in nss-lookup.target.
This matches the behaviour of systemd-resolved and Unbound.
Signed-off-by: nl6720 <nl6720@gmail.com>
Cope with cached and configured CNAMES for all record types we
support, including local-config but not cached types such as TXT.
Also, if we have a locally configured CNAME but no target for the
requested type, don't forward the query.
The idea of this option was already discussed years ago on the mailing
list:
https://dnsmasq-discuss.thekelleys.org.narkive.com/ZoFQNaGo/always-ignore-client-identifier#post4
In our production environnement, we discovered that some devices are
using 'client identifier' not unique at all, resulting on IP addresses
conflicts between several devices (we saw up to four devices using same
IP address).
The root cause is probably a buggy operating system/configuration of
decices, but this patch add a configuration workaround on server side
when fixing clients is impossible.
Signed-off-by: Charles Daymand <charles.daymand@wifirst.fr>
Signed-off-by: Florent Fourcot <florent.fourcot@wifirst.fr>
Some REFUSED answers to DNSSEC-originated queries would
bypass the DNSSEC code entirely, and be returned as answers
to the original query. In the process, they'd mess up datastructures
so that a retry of the original query would crash dnsmasq.
If no IPv4 address is present on given interface, the tool would not
send any request. It would not report any error at the same time. Report
error if request send failed.
Signed-off-by: Petr Mensik <pemensik@redhat.com>
