[Bug 1291369] [NEW] dnsmasq can't send OFFERS missing capabilities but doesn't check

[Simon Kelley]

On 12/03/14 13:24, fish wrote:
> Public bug reported:
> 
> Hi,
> 
> I'm running dnsmasq in a (docker) container. If I tried to start dnsmasq
> without arguments and it failed with:
> 
>     dnsmasq: setting capabilities failed: Operation not permitted
> 
> Guess this is expected because the container has limited privileges. The
> odd thing is, if I start it with --no-daemon it starts just fine, it
> receives the DISCOVERs and says it's sending the OFFERS. The log shows:
> 
> dnsmasq-dhcp: DHCPDISCOVER(eth1) a4:ba:db:0a:3f:ef 
> dnsmasq-dhcp: DHCPOFFER(eth1) 192.168.101.183 a4:ba:db:0a:3f:ef 
> 
> But according to tcpdump it's trying to send this as unicast which isn't
> possible (I only see arp requests to resolve 192.168.101.183).  This is
> a strace when answering the request:
> https://gist.github.com/discordianfish/687f4cb5756c9cf3d841
> 
> No idea whether this is just a obscure bug or dnsmasq trying to be
> smart.  So guess in the end it needs just better error handling/checks
> for capabilities.
> 
> ** Affects: dnsmasq (Ubuntu)
>      Importance: Undecided
>          Status: New
> 

>From the dnsmasq man page:

-d, --no-daemon
  Debug  mode:  don't  fork  to  the  background, don't write a pid
  file, don't change user id, generate a complete cache dump on
  receipt on SIGUSR1, log to stderr as well as syslog, don't fork new
  processes to handle TCP queries. Note that this  option  is
  for use in debugging only, to stop dnsmasq daemonising in production,
  use -k.


Note last sentence.

Cheers,


Simon.

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Title:
  dnsmasq can't send OFFERS missing capabilities but doesn't check

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